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  • Does anyone really understand how HFSC scheduling in Linux/BSD works?

    - by Mecki
    I read the original SIGCOMM '97 PostScript paper about HFSC, it is very technically, but I understand the basic concept. Instead of giving a linear service curve (as with pretty much every other scheduling algorithm), you can specify a convex or concave service curve and thus it is possible to decouple bandwidth and delay. However, even though this paper mentions to kind of scheduling algorithms being used (real-time and link-share), it always only mentions ONE curve per scheduling class (the decoupling is done by specifying this curve, only one curve is needed for that). Now HFSC has been implemented for BSD (OpenBSD, FreeBSD, etc.) using the ALTQ scheduling framework and it has been implemented Linux using the TC scheduling framework (part of iproute2). Both implementations added two additional service curves, that were NOT in the original paper! A real-time service curve and an upper-limit service curve. Again, please note that the original paper mentions two scheduling algorithms (real-time and link-share), but in that paper both work with one single service curve. There never have been two independent service curves for either one as you currently find in BSD and Linux. Even worse, some version of ALTQ seems to add an additional queue priority to HSFC (there is no such thing as priority in the original paper either). I found several BSD HowTo's mentioning this priority setting (even though the man page of the latest ALTQ release knows no such parameter for HSFC, so officially it does not even exist). This all makes the HFSC scheduling even more complex than the algorithm described in the original paper and there are tons of tutorials on the Internet that often contradict each other, one claiming the opposite of the other one. This is probably the main reason why nobody really seems to understand how HFSC scheduling really works. Before I can ask my questions, we need a sample setup of some kind. I'll use a very simple one as seen in the image below: Here are some questions I cannot answer because the tutorials contradict each other: What for do I need a real-time curve at all? Assuming A1, A2, B1, B2 are all 128 kbit/s link-share (no real-time curve for either one), then each of those will get 128 kbit/s if the root has 512 kbit/s to distribute (and A and B are both 256 kbit/s of course), right? Why would I additionally give A1 and B1 a real-time curve with 128 kbit/s? What would this be good for? To give those two a higher priority? According to original paper I can give them a higher priority by using a curve, that's what HFSC is all about after all. By giving both classes a curve of [256kbit/s 20ms 128kbit/s] both have twice the priority than A2 and B2 automatically (still only getting 128 kbit/s on average) Does the real-time bandwidth count towards the link-share bandwidth? E.g. if A1 and B1 both only have 64kbit/s real-time and 64kbit/s link-share bandwidth, does that mean once they are served 64kbit/s via real-time, their link-share requirement is satisfied as well (they might get excess bandwidth, but lets ignore that for a second) or does that mean they get another 64 kbit/s via link-share? So does each class has a bandwidth "requirement" of real-time plus link-share? Or does a class only have a higher requirement than the real-time curve if the link-share curve is higher than the real-time curve (current link-share requirement equals specified link-share requirement minus real-time bandwidth already provided to this class)? Is upper limit curve applied to real-time as well, only to link-share, or maybe to both? Some tutorials say one way, some say the other way. Some even claim upper-limit is the maximum for real-time bandwidth + link-share bandwidth? What is the truth? Assuming A2 and B2 are both 128 kbit/s, does it make any difference if A1 and B1 are 128 kbit/s link-share only, or 64 kbit/s real-time and 128 kbit/s link-share, and if so, what difference? If I use the seperate real-time curve to increase priorities of classes, why would I need "curves" at all? Why is not real-time a flat value and link-share also a flat value? Why are both curves? The need for curves is clear in the original paper, because there is only one attribute of that kind per class. But now, having three attributes (real-time, link-share, and upper-limit) what for do I still need curves on each one? Why would I want the curves shape (not average bandwidth, but their slopes) to be different for real-time and link-share traffic? According to the little documentation available, real-time curve values are totally ignored for inner classes (class A and B), they are only applied to leaf classes (A1, A2, B1, B2). If that is true, why does the ALTQ HFSC sample configuration (search for 3.3 Sample configuration) set real-time curves on inner classes and claims that those set the guaranteed rate of those inner classes? Isn't that completely pointless? (note: pshare sets the link-share curve in ALTQ and grate the real-time curve; you can see this in the paragraph above the sample configuration). Some tutorials say the sum of all real-time curves may not be higher than 80% of the line speed, others say it must not be higher than 70% of the line speed. Which one is right or are they maybe both wrong? One tutorial said you shall forget all the theory. No matter how things really work (schedulers and bandwidth distribution), imagine the three curves according to the following "simplified mind model": real-time is the guaranteed bandwidth that this class will always get. link-share is the bandwidth that this class wants to become fully satisfied, but satisfaction cannot be guaranteed. In case there is excess bandwidth, the class might even get offered more bandwidth than necessary to become satisfied, but it may never use more than upper-limit says. For all this to work, the sum of all real-time bandwidths may not be above xx% of the line speed (see question above, the percentage varies). Question: Is this more or less accurate or a total misunderstanding of HSFC? And if assumption above is really accurate, where is prioritization in that model? E.g. every class might have a real-time bandwidth (guaranteed), a link-share bandwidth (not guaranteed) and an maybe an upper-limit, but still some classes have higher priority needs than other classes. In that case I must still prioritize somehow, even among real-time traffic of those classes. Would I prioritize by the slope of the curves? And if so, which curve? The real-time curve? The link-share curve? The upper-limit curve? All of them? Would I give all of them the same slope or each a different one and how to find out the right slope? I still haven't lost hope that there exists at least a hand full of people in this world that really understood HFSC and are able to answer all these questions accurately. And doing so without contradicting each other in the answers would be really nice ;-)

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  • CodePlex Daily Summary for Friday, April 06, 2012

    CodePlex Daily Summary for Friday, April 06, 2012Popular ReleasesBetter Explorer: Better Explorer 2.0.0.861 Alpha: - fixed new folder button operation not work well in some situations - removed some unnecessary code like subclassing that is not needed anymore - Added option to make Better Exlorer default (at least for WIN+E operations) - Added option to enable file operation replacements (like Terracopy) to work with Better Explorer - Added some basic usability to "Share" button - Other fixesLightFarsiDictionary - ??????? ??? ?????/???????: LightFarsiDictionary - v1: LightFarsiDictionary - v1WPF Application Framework (WAF): WPF Application Framework (WAF) 2.5.0.3: Version: 2.5.0.3 (Milestone 3): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Changelog Legend: [B] Breaking change; [O] Marked member as obsolete [O] WAF: Mark the StringBuilderExtensions class as obsolete because the AppendInNewLine method can be replaced with string.Jo...Community TFS Build Extensions: April 2012: Release notes to follow...ClosedXML - The easy way to OpenXML: ClosedXML 0.65.2: Aside from many bug fixes we now have Conditional Formatting The conditional formatting was sponsored by http://www.bewing.nl (big thanks) New on v0.65.1 Fixed issue when loading conditional formatting with default values for icon sets New on v0.65.2 Fixed issue loading conditional formatting Improved inserts performanceLiberty: v3.2.0.0 Release 4th April 2012: Change Log-Added -Halo 3 support (invincibility, ammo editing) -Halo 3: ODST support (invincibility, ammo editing) -The file transfer page now shows its progress in the Windows 7 taskbar -"About this build" settings page -Reach Change what an object is carrying -Reach Change which node a carried object is attached to -Reach Object node viewer and exporter -Reach Change which weapons you are carrying from the object editor -Reach Edit the weapon controller of vehicles and turrets -An error dia...MSBuild Extension Pack: April 2012: Release Blog Post The MSBuild Extension Pack April 2012 release provides a collection of over 435 MSBuild tasks. A high level summary of what the tasks currently cover includes the following: System Items: Active Directory, Certificates, COM+, Console, Date and Time, Drives, Environment Variables, Event Logs, Files and Folders, FTP, GAC, Network, Performance Counters, Registry, Services, Sound Code: Assemblies, AsyncExec, CAB Files, Code Signing, DynamicExecute, File Detokenisation, GUID’...DotNetNuke® Community Edition CMS: 06.01.05: Major Highlights Fixed issue that stopped users from creating vocabularies when the portal ID was not zero Fixed issue that caused modules configured to be displayed on all pages to be added to the wrong container in new pages Fixed page quota restriction issue in the Ribbon Bar Removed restriction that would not allow users to use a dash in page names. Now users can create pages with names like "site-map" Fixed issue that was causing the wrong container to be loaded in modules wh...51Degrees.mobi - Mobile Device Detection and Redirection: 2.1.3.1: One Click Install from NuGet Changes to Version 2.1.3.11. [assembly: AllowPartiallyTrustedCallers] has been added back into the AssemblyInfo.cs file to prevent failures with other assemblies in Medium trust environments. 2. The Lite data embedded into the assembly has been updated to include devices from December 2011. The 42 new RingMark properties will return Unknown if RingMark data is not available. Changes to Version 2.1.2.11Code Changes 1. The project is now licenced under the Mozilla...MVC Controls Toolkit: Mvc Controls Toolkit 2.0.0: Added Support for Mvc4 beta and WebApi The SafeqQuery and HttpSafeQuery IQueryable implementations that works as wrappers aroung any IQueryable to protect it from unwished queries. "Client Side" pager specialized in paging javascript data coming either from a remote data source, or from local data. LinQ like fluent javascript api to build queries either against remote data sources, or against local javascript data, with exactly the same interface. There are 3 different query objects exp...ExtAspNet: ExtAspNet v3.1.2: ExtAspNet - ?? ExtJS ??? ASP.NET 2.0 ???,????? AJAX ?????????? ExtAspNet ????? ExtJS ??? ASP.NET 2.0 ???,????? AJAX ??????????。 ExtAspNet ??????? JavaScript,?? CSS,?? UpdatePanel,?? ViewState,?? WebServices ???????。 ??????: IE 7.0, Firefox 3.6, Chrome 3.0, Opera 10.5, Safari 3.0+ ????:Apache License 2.0 (Apache) ??:http://extasp.net/ ??:http://bbs.extasp.net/ ??:http://extaspnet.codeplex.com/ ??:http://sanshi.cnblogs.com/ ????: +2012-04-04 v3.1.2 -??IE?????????????BUG(??"about:blank"?...nopCommerce. Open source shopping cart (ASP.NET MVC): nopcommerce 2.50: Highlight features & improvements: • Significant performance optimization. • Allow store owners to create several shipments per order. Added a new shipping status: “Partially shipped”. • Pre-order support added. Enables your customers to place a Pre-Order and pay for the item in advance. Displays “Pre-order” button instead of “Buy Now” on the appropriate pages. Makes it possible for customer to buy available goods and Pre-Order items during one session. It can be managed on a product variant ...WiX Toolset: WiX v3.6 RC0: WiX v3.6 RC0 (3.6.2803.0) provides support for VS11 and a more stable Burn engine. For more information see Rob's blog post about the release: http://robmensching.com/blog/posts/2012/4/3/WiX-v3.6-Release-Candidate-Zero-availableSageFrame: SageFrame 2.0: Sageframe is an open source ASP.NET web development framework developed using ASP.NET 3.5 with service pack 1 (sp1) technology. It is designed specifically to help developers build dynamic website by providing core functionality common to most web applications.iTuner - The iTunes Companion: iTuner 1.5.4475: Fix to parse empty playlists in iTunes LibraryDocument.Editor: 2012.2: Whats New for Document.Editor 2012.2: New Save Copy support New Page Setup support Minor Bug Fix's, improvements and speed upsDotNet.Highcharts: DotNet.Highcharts 1.2 with Examples: Tested and adapted to the latest version of Highcharts 2.2.1 Fixed Issue 359: Not implemented serialization array of type: System.Drawing.Color[] Fixed Issue 364: Crosshairs defined as array of CrosshairsForamt generates bad Highchart code For the example project: Added newest version of Highcharts 2.2.1 Added new demos to How To's section: Bind Data From Dictionary Bind Data From Object List Custom Theme Tooltip Crosshairs Theming The Reset Button Plot Band EventsVidCoder: 1.3.2: Added option for the minimum title length to scan. Added support to enable or disable LibDVDNav. Added option to prompt to delete source files after clearing successful completed items. Added option to disable remembering recent files and folders. Tweaked number box to only select all on a quick click.MJP's DirectX 11 Samples: Light Indexed Deferred Rendering: Implements light indexed deferred using per-tile light lists calculated in a compute shader, as well as a traditional deferred renderer that uses a compute shader for per-tile light culling and per-pixel shading.Pcap.Net: Pcap.Net 0.9.0 (66492): Pcap.Net - March 2012 Release Pcap.Net is a .NET wrapper for WinPcap written in C++/CLI and C#. It Features almost all WinPcap features and includes a packet interpretation framework. Version 0.9.0 (Change Set 66492)March 31, 2012 release of the Pcap.Net framework. Follow Pcap.Net on Google+Follow Pcap.Net on Google+ Files Pcap.Net.DevelopersPack.0.9.0.66492.zip - Includes all the tutorial example projects source files, the binaries in a 3rdParty directory and the documentation. It include...New Projects.Net Mutation Testing Tool: This tool will help for making and unit testing mutation changes. Mutation tests improve unit tests and applications.African Honey Bee Application Suite: This is the home of the software behind the African Honey Bee community enrichment project.Create Schema: Object extension method that generates schema creation scripts in SQL (MS SQL SERVER) from c# classes to rapidly get database tables from an existing class structure. Just edit the scripts (they are just guesses of how the database should look) to make them fit your database needs and then run them as a query in SQL Server. Check out vecklare.blogspot.se for more examples. CrtTfsDemo: demo project to test code review tool integration with tfsDolphins Salaam: This Library is a Cross Platform, UDP Broadcast solution for Peer to Peer network client detection. It is written in pure C# and is Mono and .Net compatible. It has been tested on Mac OS X, Windows, Linux, iOS, Android, Xbox and it is expected to be compatible with every other Mono compatible platform. The library is ready to use out of box and there is almost zero configurations needed for it to start working, regarding that, it is also flexible and configurable for your needs.Enhanced Content Query Webpart: This Enhanced Content Query Webpart for SharePoint 2010 is meant for the advanced application developer. You will be able to create any rollup of pages of any Content Type(s), Site Column(s) from any subsite(s) with (any) style you want. Xslt skills are required.fangxue: huijiaFrameworkComponent: frameworkcomponent 4 companyFsXna3DGame: 3D game written in XNA and F# (still very much a work in progress)GeoLock: GeoLock is a proof of concept (PoC). GeoLock demonstrates how to retrieve geolocation data from surrounding Wi-Fi networks triangulation without Global Positioning System (GPS) hardware. grab-libs: A quick hack to bundle up the shared libraries needed to run an i386 executable on an x86_64 machine.Logical Game Of Life: Make Logic Component with a game of life algoritmMagic Box: Magic Box is the application for "hiding" files in NTFS file system. NTFS Alternate Data Streams are used for this.Notes: Application to create fast notes on your Windows Phone.Orchard Google Infographics: **NOTE: Only works with Orchard >= v1.4** This module leverages Google's Infographics api for generating QR codes for each content item that uses the Orchard.Autoroute part. The api documentation may be found at https://developers.google.com/chart/infographics/docs/qr_codesOutlook Calendar Cleaner: If you port your email from a Lotus Notes server to Exchange Server or to Office 365, your Mac Outlook calendar items may be missing. This includes calendar appointments and meeting requests. This may include items that were ported over and also new items created after the port.Polarity: Polarity is a plugin-oriented bot written in C# for deviantArt chat written with simplicity and ease of use for plugin developers as the number one goal.Pool Game Paradise: Pool Game Club of Augmentum Inc. Wuhan Site.RCT2 DatChecker: A utility for Rollercoaster Tycoon 2 that catalogs, displays, and helps manage object files (*.DAT). Examine objects frame by frame or copy object images to the clipboard. Sort objects by size, type, or content. Use DatChecker to find and remove unwanted or duplicate objects, or RecipeML Manager: This project creates C# classes that support the RecipeML standard. It also enhances that standard to support full daily and weekly menus.s0t0o0c0k3246352543: 345234324324324324ScoutGames: scout games portalSharePoint All Page Scripting: This solution is the skeleton of the JavaScript loading in all pages on the SharePoint site collection. This solution can be deployed as a "sandbox solution". Supports the Office365 of course. ??????????SharePoint ?????????????????????????Java?????????????。 ????????????????????????。 ???、????Office365?????????。testtom04052012git02: testtom04052012git02testtom04052012tfs01: testtom04052012tfs01testtom04052012tfs03: testtom04052012tfs03Visual Studio Pattern Automation Toolkit (VSPAT): VSPAT is a set of development and deployment tools from Microsoft that generate and execute Visual Studio extensions called 'Pattern Toolkits' that redeliver best practices, expertise and proven solutions faster, more reliably and more consistently. If you are an *IT professional* are you are looking to build and deploy custom solutions that include proven best practices to improve quality, consistency and time to market. And if you wish to spend significantly less time having to learn all...Wet: Wet, the game.WPF Data Editors: WPF Data Editor controls contains most of editor controls in WPF.xSolon Instructions: Framework to run scripts

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  • The case of the phantom ADF developer (and other yarns)

    - by Chris Muir
    A few years of ADF experience means I see common mistakes made by different developers, some I regularly make myself.  This post is designed to assist beginners to Oracle JDeveloper Application Development Framework (ADF) avoid a common ADF pitfall, the case of the phantom ADF developer [add Scooby-Doo music here]. ADF Business Components - triggers, default table values and instead of views. Oracle's JDeveloper tutorials help with the A-B-Cs of ADF development, typically built on the nice 'n safe demo schema provided by with the Oracle database such as the HR demo schema. However it's not too long until ADF beginners, having built up some confidence from learning with the tutorials and vanilla demo schemas, start building ADF Business Components based upon their own existing database schema objects.  This is where unexpected problems can sneak in. The crime Developers may encounter a surprising error at runtime when editing a record they just created or updated and committed to the database, based on their own existing tables, namely the error: JBO-25014: Another user has changed the row with primary key oracle.jbo.Key[x] ...where X is the primary key value of the row at hand.  In a production environment with multiple users this error may be legit, one of the other users has updated the row since you queried it.  Yet in a development environment this error is just plain confusing.  If developers are isolated in their own database, creating and editing records they know other users can't possibly be working with, or all the other developers have gone home for the day, how is this error possible? There are no other users?  It must be the phantom ADF developer! [insert dramatic music here] The following picture is what you'll see in the Business Component Browser, and you'll receive a similar error message via an ADF Faces page: A false conclusion What can possibly cause this issue if it isn't our phantom ADF developer?  Doesn't ADF BC implement record locking, locking database records when the row is modified in the ADF middle-tier by a user?  How can our phantom ADF developer even take out a lock if this is the case?  Maybe ADF has a bug, maybe ADF isn't implementing record locking at all?  Shouldn't we see the error "JBO-26030: Failed to lock the record, another user holds the lock" as we attempt to modify the record, why do we see JBO-25014? : Let's verify that ADF is in fact issuing the correct SQL LOCK-FOR-UPDATE statement to the database. First we need to verify ADF's locking strategy.  It is determined by the Application Module's jbo.locking.mode property.  The default (as of JDev 11.1.1.4.0 if memory serves me correct) and recommended value is optimistic, and the other valid value is pessimistic. Next we need a mechanism to check that ADF is issuing the LOCK statements to the database.  We could ask DBAs to monitor locks with OEM, but optimally we'd rather not involve overworked DBAs in this process, so instead we can use the ADF runtime setting –Djbo.debugoutput=console.  At runtime this options turns on instrumentation within the ADF BC layer, which among a lot of extra detail displayed in the log window, will show the actual SQL statement issued to the database, including the LOCK statement we're looking to confirm. Setting our locking mode to pessimistic, opening the Business Components Browser of a JSF page allowing us to edit a record, say the CHARGEABLE field within a BOOKINGS record where BOOKING_NO = 1206, upon editing the record see among others the following log entries: [421] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[422] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[423] Where binding param 1: 1206  As can be seen on line 422, in fact a LOCK-FOR-UPDATE is indeed issued to the database.  Later when we commit the record we see: [441] OracleSQLBuilder: SAVEPOINT 'BO_SP'[442] OracleSQLBuilder Executing, Lock 1 DML on: BOOKINGS (Update)[443] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[444] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[445] Update binding param 1: N[446] Where binding param 2: 1206[447] BookingsView1 notify COMMIT ... [448] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [449] EntityCache close prepared statement ....and as a result the changes are saved to the database, and the lock is released. Let's see what happens when we use the optimistic locking mode, this time to change the same BOOKINGS record CHARGEABLE column again.  As soon as we edit the record we see little activity in the logs, nothing to indicate any SQL statement, let alone a LOCK has been taken out on the row. However when we save our records by issuing a commit, the following is recorded in the logs: [509] OracleSQLBuilder: SAVEPOINT 'BO_SP'[510] OracleSQLBuilder Executing doEntitySelect on: BOOKINGS (true)[511] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[512] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[513] Where binding param 1: 1205[514] OracleSQLBuilder Executing, Lock 2 DML on: BOOKINGS (Update)[515] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[516] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[517] Update binding param 1: Y[518] Where binding param 2: 1205[519] BookingsView1 notify COMMIT ... [520] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [521] EntityCache close prepared statement Again even though we're seeing the midtier delay the LOCK statement until commit time, it is in fact occurring on line 412, and released as part of the commit issued on line 419.  Therefore with either optimistic or pessimistic locking a lock is indeed issued. Our conclusion at this point must be, unless there's the unlikely cause the LOCK statement is never really hitting the database, or the even less likely cause the database has a bug, then ADF does in fact take out a lock on the record before allowing the current user to update it.  So there's no way our phantom ADF developer could even modify the record if he tried without at least someone receiving a lock error. Hmm, we can only conclude the locking mode is a red herring and not the true cause of our problem.  Who is the phantom? At this point we'll need to conclude that the error message "JBO-25014: Another user has changed" is somehow legit, even though we don't understand yet what's causing it. This leads onto two further questions, how does ADF know another user has changed the row, and what's been changed anyway? To answer the first question, how does ADF know another user has changed the row, the Fusion Guide's section 4.10.11 How to Protect Against Losing Simultaneous Updated Data , that details the Entity Object Change-Indicator property, gives us the answer: At runtime the framework provides automatic "lost update" detection for entity objects to ensure that a user cannot unknowingly modify data that another user has updated and committed in the meantime. Typically, this check is performed by comparing the original values of each persistent entity attribute against the corresponding current column values in the database at the time the underlying row is locked. Before updating a row, the entity object verifies that the row to be updated is still consistent with the current state of the database.  The guide further suggests to make this solution more efficient: You can make the lost update detection more efficient by identifying any attributes of your entity whose values you know will be updated whenever the entity is modified. Typical candidates include a version number column or an updated date column in the row.....To detect whether the row has been modified since the user queried it in the most efficient way, select the Change Indicator option to compare only the change-indicator attribute values. We now know that ADF BC doesn't use the locking mechanism at all to protect the current user against updates, but rather it keeps a copy of the original record fetched, separate to the user changed version of the record, and it compares the original record against the one in the database when the lock is taken out.  If values don't match, be it the default compare-all-columns behaviour, or the more efficient Change Indicator mechanism, ADF BC will throw the JBO-25014 error. This leaves one last question.  Now we know the mechanism under which ADF identifies a changed row, what we don't know is what's changed and who changed it? The real culprit What's changed?  We know the record in the mid-tier has been changed by the user, however ADF doesn't use the changed record in the mid-tier to compare to the database record, but rather a copy of the original record before it was changed.  This leaves us to conclude the database record has changed, but how and by who? There are three potential causes: Database triggers The database trigger among other uses, can be configured to fire PLSQL code on a database table insert, update or delete.  In particular in an insert or update the trigger can override the value assigned to a particular column.  The trigger execution is actioned by the database on behalf of the user initiating the insert or update action. Why this causes the issue specific to our ADF use, is when we insert or update a record in the database via ADF, ADF keeps a copy of the record written to the database.  However the cached record is instantly out of date as the database triggers have modified the record that was actually written to the database.  Thus when we update the record we just inserted or updated for a second time to the database, ADF compares its original copy of the record to that in the database, and it detects the record has been changed – giving us JBO-25014. This is probably the most common cause of this problem. Default values A second reason this issue can occur is another database feature, default column values.  When creating a database table the schema designer can define default values for specific columns.  For example a CREATED_BY column could be set to SYSDATE, or a flag column to Y or N.  Default values are only used by the database when a user inserts a new record and the specific column is assigned NULL.  The database in this case will overwrite the column with the default value. As per the database trigger section, it then becomes apparent why ADF chokes on this feature, though it can only specifically occur in an insert-commit-update-commit scenario, not the update-commit-update-commit scenario. Instead of trigger views I must admit I haven't double checked this scenario but it seems plausible, that of the Oracle database's instead of trigger view (sometimes referred to as instead of views).  A view in the database is based on a query, and dependent on the queries complexity, may support insert, update and delete functionality to a limited degree.  In order to support fully insertable, updateable and deletable views, Oracle introduced the instead of view, that gives the view designer the ability to not only define the view query, but a set of programmatic PLSQL triggers where the developer can define their own logic for inserts, updates and deletes. While this provides the database programmer a very powerful feature, it can cause issues for our ADF application.  On inserting or updating a record in the instead of view, the record and it's data that goes in is not necessarily the data that comes out when ADF compares the records, as the view developer has the option to practically do anything with the incoming data, including throwing it away or pushing it to tables which aren't used by the view underlying query for fetching the data. Readers are at this point reminded that this article is specifically about how the JBO-25014 error occurs in the context of 1 developer on an isolated database.  The article is not considering how the error occurs in a production environment where there are multiple users who can cause this error in a legitimate fashion.  Assuming none of the above features are the cause of the problem, and optimistic locking is turned on (this error is not possible if pessimistic locking is the default mode *and* none of the previous causes are possible), JBO-25014 is quite feasible in a production ADF application if 2 users modify the same record. At this point under project timelines pressure, the obvious fix for developers is to drop both database triggers and default values from the underlying tables.  However we must be careful that these legacy constructs aren't used and assumed to be in place by other legacy systems.  Dropping the database triggers or default value that the existing Oracle Forms  applications assumes and requires to be in place could cause unexpected behaviour and bugs in the Forms application.  Proficient software engineers would recognize such a change may require a partial or full regression test of the existing legacy system, a potentially costly and timely exercise, not ideal. Solving the mystery once and for all Luckily ADF has built in functionality to deal with this issue, though it's not a surprise, as Oracle as the author of ADF also built the database, and are fully aware of the Oracle database's feature set.  At the Entity Object attribute level, the Refresh After Insert and Refresh After Update properties.  Simply selecting these instructs ADF BC after inserting or updating a record to the database, to expect the database to modify the said attributes, and read a copy of the changed attributes back into its cached mid-tier record.  Thus next time the developer modifies the current record, the comparison between the mid-tier record and the database record match, and JBO-25014: Another user has changed" is no longer an issue. [Post edit - as per the comment from Oracle's Steven Davelaar below, as he correctly points out the above solution will not work for instead-of-triggers views as it relies on SQL RETURNING clause which is incompatible with this type of view] Alternatively you can set the Change Indicator on one of the attributes.  This will work as long as the relating column for the attribute in the database itself isn't inadvertently updated.  In turn you're possibly just masking the issue rather than solving it, because if another developer turns the Change Indicator back on the original issue will return.

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  • CodePlex Daily Summary for Saturday, March 05, 2011

    CodePlex Daily Summary for Saturday, March 05, 2011Popular ReleasesXsltDb - DotNetNuke Module Builder: 02.00.66: Using XsltDb As User Controladding XsltDb configurations to skin, to your controls, ... Page level output cachingAlso takes into account current user current language see mdo:setup-putput-cache. Performance optimizations......for large configurations or large outputAutoLoL: AutoLoL v1.6.4: It is now possible to run the clicker anyway when it can't detect the Masteries Window Fixed a critical bug in the open file dialog Removed the resize button Some UI changes 3D camera movement is now more intuitive (Trackball rotation) When an error occurs on the clicker it will attempt to focus AutoLoLYAF.NET (aka Yet Another Forum.NET): v1.9.5.5 RTW: YAF v1.9.5.5 RTM (Date: 3/4/2011 Rev: 4742) Official Discussion Thread here: http://forum.yetanotherforum.net/yaf_postsm47149_v1-9-5-5-RTW--Date-3-4-2011-Rev-4742.aspx Changes in v1.9.5.5 Rev. #4661 - Added "Copy" function to forum administration -- Now instead of having to manually re-enter all the access masks, etc, you can just duplicate an existing forum and modify after the fact. Rev. #4642 - New Setting to Enable/Disable Last Unread posts links Rev. #4641 - Added Arabic Language t...youtubeFisher: YouTubeFisher v3.0 Beta: Adding support for more video formats including the Super HD (e.g. http://www.youtube.com/watch?v=MrrHs2bnHPA) Minor change related to the video title due to change in YouTube pageSnippet Designer: Snippet Designer 1.3.1: Snippet Designer 1.3.1 for Visual Studio 2010This is a bug fix release. Change logFixed bug where Snippet Designer would fail if you had the most recent Productivity Power Tools installed Fixed bug where "Export as Snippet" was failing in non-english locales Fixed bug where opening a new .snippet file would fail in non-english localesChiave File Encryption: Chiave 1.0: Final Relase for Chave 1.0 Stable: Application for file encryption and decryption using 512 Bit rijndael encyrption algorithm with simple to use UI. Its written in C# and compiled in .Net version 3.5. It incorporates features of Windows 7 like Jumplists, Taskbar progress and Aero Glass. Now with added support to Windows XP! Change Log from 0.9.2 to 1.0: ==================== Added: > Added Icon Overlay for Windows 7 Taskbar Icon. >Added Thumbnail Toolbar buttons to make the navigation easier...ASP.NET: Sprite and Image Optimization Preview 3: The ASP.NET Sprite and Image Optimization framework is designed to decrease the amount of time required to request and display a page from a web server by performing a variety of optimizations on the page’s images. This is the third preview of the feature and works with ASP.NET Web Forms 4, ASP.NET MVC 3, and ASP.NET Web Pages (Razor) projects. The binaries are also available via NuGet: AspNetSprites-Core AspNetSprites-WebFormsControl AspNetSprites-MvcAndRazorHelper It includes the foll...Document.Editor: 2011.9: Whats new for Document.Editor 2011.9: New Templates System New Plug-in System New Replace dialog New reset settings Minor Bug Fix's, improvements and speed upsTortoiseHg: TortoiseHg 2.0: TortoiseHg 2.0 is a complete rewrite of TortoiseHg 1.1, switching from PyGtk to PyQtSandcastle Help File Builder: SHFB v1.9.2.0 Release: This release supports the Sandcastle June 2010 Release (v2.6.10621.1). It includes full support for generating, installing, and removing MS Help Viewer files. This new release is compiled under .NET 4.0, supports Visual Studio 2010 solutions and projects as documentation sources, and adds support for projects targeting the Silverlight Framework. NOTE: The included help file and the online help have not been completely updated to reflect all changes in this release. A refresh will be issue...Network Monitor Open Source Parsers: Microsoft Network Monitor Parsers 3.4.2554: The Network Monitor Parsers packages contain parsers for more than 400 network protocols, including RFC based public protocols and protocols for Microsoft products defined in the Microsoft Open Specifications for Windows and SQL Server. NetworkMonitor_Parsers.msi is the base parser package which defines parsers for commonly used public protocols and protocols for Microsoft Windows. In this release, we have added 4 new protocol parsers and updated 79 existing parsers in the NetworkMonitor_Pa...Image Resizer for Windows: Image Resizer 3 Preview 1: Prepare to have your minds blown. This is the first preview of what will eventually become 39613. There are still a lot of rough edges and plenty of areas still under construction, but for your basic needs, it should be relativly stable. Note: You will need the .NET Framework 4 installed to use this version. Below is a status report of where this release is in terms of the overall goal for version 3. If you're feeling a bit technically ambitious and want to check out some of the features th...JSON Toolkit: JSON Toolkit 1.1: updated GetAllJsonObjects() method and GetAllProperties() methods to JsonObject and Properties propertiesFacebook Graph Toolkit: Facebook Graph Toolkit 1.0: Refer to http://computerbeacon.net for Documentation and Tutorial New features:added FQL support added Expires property to Api object added support for publishing to a user's friend / Facebook Page added support for posting and removing comments on posts added support for adding and removing likes on posts and comments added static methods for Page class added support for Iframe Application Tab of Facebook Page added support for obtaining the user's country, locale and age in If...ASP.NET MVC Project Awesome, jQuery Ajax helpers (controls): 1.7.1: A rich set of helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager small improvements for some helpers and AjaxDropdown has Data like the Lookup except it's value gets reset and list refilled if any element from data gets changedManaged Extensibility Framework: MEF 2 Preview 3: This release aims .net 4.0 and Silverlight 4.0. Accordingly, there are two solutions files. The assemblies are named System.ComponentModel.Composition.Codeplex.dll as a way to avoid clashing with the version shipped with the 4th version of the framework. Introduced CompositionOptions to container instantiation CompositionOptions.DisableSilentRejection makes MEF throw an exception on composition errors. Useful for diagnostics Support for open generics Support for attribute-less registr...PHPExcel: PHPExcel 1.7.6 Production: DonationsDonate via PayPal via PayPal. If you want to, we can also add your name / company on our Donation Acknowledgements page. PEAR channelWe now also have a full PEAR channel! Here's how to use it: New installation: pear channel-discover pear.pearplex.net pear install pearplex/PHPExcel Or if you've already installed PHPExcel before: pear upgrade pearplex/PHPExcel The official page can be found at http://pearplex.net. Want to contribute?Please refer the Contribute page.WPF Application Framework (WAF): WPF Application Framework (WAF) 2.0.0.4: Version: 2.0.0.4 (Milestone 4): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Remark The sample applications are using Microsoft’s IoC container MEF. However, the WPF Application Framework (WAF) doesn’t force you to use the same IoC container in your application. You can use ...VidCoder: 0.8.2: Updated auto-naming to handle seconds and frames ranges as well. Deprecated the {chapters} token for auto-naming in favor of {range}. Allowing file drag to preview window and enabling main window shortcut keys to work no matter what window is focused. Added option in config to enable giving custom names to audio tracks. (Note that these names will only show up certain players like iTunes or on the iPod. Players that support custom track names normally may not show them.) Added tooltips ...SQL Server Compact Toolbox: Standalone version 2.0 for SQL Server Compact 4.0: Download the Visual Studio add-in for SQL Server Compact 4.0 and 3.5 from here Standalone version of (most of) the same functionality as the add-in, for SQL Server Compact 4.0. Useful for anyone not having Visual Studio Professional or higher installed. Requires .NET 4.0. Any feedback much appreciated.New Projects.Deploy - Enterprise .NET Application Deployment Solution: .Deploy is a .NET based enterprise application deployment solution focused around .NET applications. .Deploy automates the repetitive task of pushing/deploying applications in a controlled, auditable, and verifiable way.AAEngine: A 2D game engine for XNA.ANKASTS: ankastsAutomator: Automator is a GUI tool that is intended to manage and run hierarchical structure of actions (Tasks). Something similar to NAnt but targeted for a far wider audience. Automator is developed in C# and WPF.BANews: ???????????????????,??SQL+Server2008,C#,asp.net????,??????Jquery?CSS+DIV??。??????,?????????????,????????,??????,??。Cloud BookShelf: Cloud BookShelf ?OData Client for Objective-C(http://odataobjc.codeplex.com/)????、Azure??????????????iOS??????????。CodingBlog: codingblogDNN Module Samples: There are some sample DNN modules in this projectEITEST: It is the Test Projecteuler 11: euler 11euler 52 problem: euler 52 problemfastspweb - Access SPWeb through cache: This an engine for caching SPSite and SPWeb objects on SharePoint. Because SharePoint dont alllow multithreaded access to these objects, the access is done through a threadpoolGSP420 2011 Spring Course Project: Course project game engine for DeVry Spring 2011 GSP420 class.IE Library for Small Basic: This library extend Small Basic to allows you to access web site using by Internet Explorer from Small Basic program. ???????? Small Basic ????、Small Basic ??? Internet Explorer ???? Web ???????????????????。InfoStrat Motion Framework: InfoStrat Motion Framework enables you to easily use motion tracking in your WPF applications with depth sensors such as Kinect and PrimeSensor.JSC.Mobile: Mobile(IPhone) WebApp with offline capabilities to administrate your car milagesMSSQL Db Generation From and To .NET Assemblies(Dlls): MSSQL DbGenerator works with an existing MSSQL Db and codes all structers of it into a .NET Assembly(DbAssembly) --of course with the exception of data within. More than that it has the ability to read any previously created DbAssembly and generates MSSQL db from scratchMVP Summit Events WP7: An application to learn of the best gatherings and events at the Microsoft MVP Summit in 2011. We are open sourcing the application to give some knowledge around how to develop a Windows Phone 7 application consuming OData with the MVVM pattern.NAntMenu: NAntMenu Shell Extension is a Windows Shell Extension allowing you to run NAnt build scripts directly from within Windows Explorer.NGem: another attempt to create package management in .net/c++ environmentNOrder: A basic sorting algorithm library developed in C#, providing users the flexibility to choose how to sort data.Orchard CulturePicker Module: Module for Orchard, that allows users to pick a preferred culture, instead of using a default site culture.Orchard Html Field Module: Html Field for the Orchard ProjectP9876: p9876 is not p1234SharePoint 2010 File Migrating tool (console program): Copy files and sub folders from file system to SharePoint 2010 document librarySilverlightTube: Silverlight Media End Work Project to recreate a You Tube looking websiteSITEYONETIM: Site ve Apartman YönetimiSITEYONETIMWEB: siteyonetimwebSteel: Steel is a puzzle game for Windows Phone 7 made with the XNA framework.WikiVB: A Wikipedia API wrapper library written in VB.NET. Can be used with languages like C#, F# and other .NET programming languages.

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  • A jQuery Plug-in to monitor Html Element CSS Changes

    - by Rick Strahl
    Here's a scenario I've run into on a few occasions: I need to be able to monitor certain CSS properties on an HTML element and know when that CSS element changes. The need for this arose out of wanting to build generic components that could 'attach' themselves to other objects and monitor changes on the ‘parent’ object so the dependent object can adjust itself accordingly. What I wanted to create is a jQuery plug-in that allows me to specify a list of CSS properties to monitor and have a function fire in response to any change to any of those CSS properties. The result are the .watch() and .unwatch() jQuery plug-ins. Here’s a simple example page of this plug-in that demonstrates tracking changes to an element being moved with draggable and closable behavior: http://www.west-wind.com/WestWindWebToolkit/samples/Ajax/jQueryPluginSamples/WatcherPlugin.htm Try it with different browsers – IE and FireFox use the DOM event handlers and Chrome, Safari and Opera use setInterval handlers to manage this behavior. It should work in all of them but all but IE and FireFox will show a bit of lag between the changes in the main element and the shadow. The relevant HTML for this example is this fragment of a main <div> (#notebox) and an element that is to mimic a shadow (#shadow). <div class="containercontent"> <div id="notebox" style="width: 200px; height: 150px;position: absolute; z-index: 20; padding: 20px; background-color: lightsteelblue;"> Go ahead drag me around and close me! </div> <div id="shadow" style="background-color: Gray; z-index: 19;position:absolute;display: none;"> </div> </div> The watcher plug in is then applied to the main <div> and shadow in sync with the following plug-in code: <script type="text/javascript"> $(document).ready(function () { var counter = 0; $("#notebox").watch("top,left,height,width,display,opacity", function (data, i) { var el = $(this); var sh = $("#shadow"); var propChanged = data.props[i]; var valChanged = data.vals[i]; counter++; showStatus("Prop: " + propChanged + " value: " + valChanged + " " + counter); var pos = el.position(); var w = el.outerWidth(); var h = el.outerHeight(); sh.css({ width: w, height: h, left: pos.left + 5, top: pos.top + 5, display: el.css("display"), opacity: el.css("opacity") }); }) .draggable() .closable() .css("left", 10); }); </script> When you run this page as you drag the #notebox element the #shadow element will maintain and stay pinned underneath the #notebox element effectively keeping the shadow attached to the main element. Likewise, if you hide or fadeOut() the #notebox element the shadow will also go away – show the #notebox element and the shadow also re-appears because we are assigning the display property from the parent on the shadow. Note we’re attaching the .watch() plug-in to the #notebox element and have it fire whenever top,left,height,width,opacity or display CSS properties are changed. The passed data element contains a props[] and vals[] array that holds the properties monitored and their current values. An index passed as the second parm tells you which property has changed and what its current value is (propChanged/valChanged in the code above). The rest of the watcher handler code then deals with figuring out the main element’s position and recalculating and setting the shadow’s position using the jQuery .css() function. Note that this is just an example to demonstrate the watch() behavior here – this is not the best way to create a shadow. If you’re interested in a more efficient and cleaner way to handle shadows with a plug-in check out the .shadow() plug-in in ww.jquery.js (code search for fn.shadow) which uses native CSS features when available but falls back to a tracked shadow element on browsers that don’t support it, which is how this watch() plug-in came about in the first place :-) How does it work? The plug-in works by letting the user specify a list of properties to monitor as a comma delimited string and a handler function: el.watch("top,left,height,width,display,opacity", function (data, i) {}, 100, id) You can also specify an interval (if no DOM event monitoring isn’t available in the browser) and an ID that identifies the event handler uniquely. The watch plug-in works by hooking up to DOMAttrModified in FireFox, to onPropertyChanged in Internet Explorer, or by using a timer with setInterval to handle the detection of changes for other browsers. Unfortunately WebKit doesn’t support DOMAttrModified consistently at the moment so Safari and Chrome currently have to use the slower setInterval mechanism. In response to a changed property (or a setInterval timer hit) a JavaScript handler is fired which then runs through all the properties monitored and determines if and which one has changed. The DOM events fire on all property/style changes so the intermediate plug-in handler filters only those hits we’re interested in. If one of our monitored properties has changed the specified event handler function is called along with a data object and an index that identifies the property that’s changed in the data.props/data.vals arrays. The jQuery plugin to implement this functionality looks like this: (function($){ $.fn.watch = function (props, func, interval, id) { /// <summary> /// Allows you to monitor changes in a specific /// CSS property of an element by polling the value. /// when the value changes a function is called. /// The function called is called in the context /// of the selected element (ie. this) /// </summary> /// <param name="prop" type="String">CSS Properties to watch sep. by commas</param> /// <param name="func" type="Function"> /// Function called when the value has changed. /// </param> /// <param name="interval" type="Number"> /// Optional interval for browsers that don't support DOMAttrModified or propertychange events. /// Determines the interval used for setInterval calls. /// </param> /// <param name="id" type="String">A unique ID that identifies this watch instance on this element</param> /// <returns type="jQuery" /> if (!interval) interval = 100; if (!id) id = "_watcher"; return this.each(function () { var _t = this; var el$ = $(this); var fnc = function () { __watcher.call(_t, id) }; var data = { id: id, props: props.split(","), vals: [props.split(",").length], func: func, fnc: fnc, origProps: props, interval: interval, intervalId: null }; // store initial props and values $.each(data.props, function (i) { data.vals[i] = el$.css(data.props[i]); }); el$.data(id, data); hookChange(el$, id, data); }); function hookChange(el$, id, data) { el$.each(function () { var el = $(this); if (typeof (el.get(0).onpropertychange) == "object") el.bind("propertychange." + id, data.fnc); else if ($.browser.mozilla) el.bind("DOMAttrModified." + id, data.fnc); else data.intervalId = setInterval(data.fnc, interval); }); } function __watcher(id) { var el$ = $(this); var w = el$.data(id); if (!w) return; var _t = this; if (!w.func) return; // must unbind or else unwanted recursion may occur el$.unwatch(id); var changed = false; var i = 0; for (i; i < w.props.length; i++) { var newVal = el$.css(w.props[i]); if (w.vals[i] != newVal) { w.vals[i] = newVal; changed = true; break; } } if (changed) w.func.call(_t, w, i); // rebind event hookChange(el$, id, w); } } $.fn.unwatch = function (id) { this.each(function () { var el = $(this); var data = el.data(id); try { if (typeof (this.onpropertychange) == "object") el.unbind("propertychange." + id, data.fnc); else if ($.browser.mozilla) el.unbind("DOMAttrModified." + id, data.fnc); else clearInterval(data.intervalId); } // ignore if element was already unbound catch (e) { } }); return this; } })(jQuery); Note that there’s a corresponding .unwatch() plug-in that can be used to stop monitoring properties. The ID parameter is optional both on watch() and unwatch() – a standard name is used if you don’t specify one, but it’s a good idea to use unique names for each element watched to avoid overlap in event ids especially if you’re monitoring many elements. The syntax is: $.fn.watch = function(props, func, interval, id) props A comma delimited list of CSS style properties that are to be watched for changes. If any of the specified properties changes the function specified in the second parameter is fired. func The function fired in response to a changed styles. Receives this as the element changed and an object parameter that represents the watched properties and their respective values. The first parameter is passed in this structure: { id: watcherId, props: [], vals: [], func: thisFunc, fnc: internalHandler, origProps: strPropertyListOnWatcher }; A second parameter is the index of the changed property so data.props[i] or data.vals[i] gets the property and changed value. interval The interval for setInterval() for those browsers that don't support property watching in the DOM. In milliseconds. id An optional id that identifies this watcher. Required only if multiple watchers might be hooked up to the same element. The default is _watcher if not specified. It’s been a Journey I started building this plug-in about two years ago and had to make many modifications to it in response to changes in jQuery and also in browser behaviors. I think the latest round of changes made should make this plug-in fairly future proof going forward (although I hope there will be better cross-browser change event notifications in the future). One of the big problems I ran into had to do with recursive change notifications – it looks like starting with jQuery 1.44 and later, jQuery internally modifies element properties on some calls to some .css()  property retrievals and things like outerHeight/Width(). In IE this would cause nasty lock up issues at times. In response to this I changed the code to unbind the events when the handler function is called and then rebind when it exits. This also makes user code less prone to stack overflow recursion as you can actually change properties on the base element. It also means though that if you change one of the monitors properties in the handler the watch() handler won’t fire in response – you need to resort to a setTimeout() call instead to force the code to run outside of the handler: $("#notebox") el.watch("top,left,height,width,display,opacity", function (data, i) { var el = $(this); … // this makes el changes work setTimeout(function () { el.css("top", 10) },10); }) Since I’ve built this component I’ve had a lot of good uses for it. The .shadow() fallback functionality is one of them. Resources The watch() plug-in is part of ww.jquery.js and the West Wind West Wind Web Toolkit. You’re free to use this code here or the code from the toolkit. West Wind Web Toolkit Latest version of ww.jquery.js (search for fn.watch) watch plug-in documentation © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  JavaScript  jQuery  

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  • CodePlex Daily Summary for Tuesday, January 04, 2011

    CodePlex Daily Summary for Tuesday, January 04, 2011Popular ReleasesMini Memory Dump Diagnosis using Asp.Net: MiniDump HealthMonitor: Enable developers to generate mini memory dumps in case of unhandled exceptions or for specific exception scenarios without using any external tools , only using Asp.Net 2.0 and above. Many times in production , QA Servers the issues require post-mortem or low-level system debugging efforts. This Memory dump generator will help in those scenarios.EnhSim: EnhSim 2.2.9 BETA: 2.2.9 BETAThis release supports WoW patch 4.03a at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - Added in the Gobl...xUnit.net - Unit Testing for .NET: xUnit.net 1.7 Beta: xUnit.net release 1.7 betaBuild #1533 Important notes for Resharper users: Resharper support has been moved to the xUnit.net Contrib project. Important note for TestDriven.net users: If you are having issues running xUnit.net tests in TestDriven.net, especially on 64-bit Windows, we strongly recommend you upgrade to TD.NET version 3.0 or later. This release adds the following new features: Added support for ASP.NET MVC 3 Added Assert.Equal(double expected, double actual, int precision)...Json.NET: Json.NET 4.0 Release 1: New feature - Added Windows Phone 7 project New feature - Added dynamic support to LINQ to JSON New feature - Added dynamic support to serializer New feature - Added INotifyCollectionChanged to JContainer in .NET 4 build New feature - Added ReadAsDateTimeOffset to JsonReader New feature - Added ReadAsDecimal to JsonReader New feature - Added covariance to IJEnumerable type parameter New feature - Added XmlSerializer style Specified property support New feature - Added ...StyleCop for ReSharper: StyleCop for ReSharper 5.1.14977.000: Prerequisites: ============== o Visual Studio 2008 / Visual Studio 2010 o ReSharper 5.1.1753.4 o StyleCop 4.4.1.2 Preview This release adds no new features, has bug fixes around performance and unhandled errors reported on YouTrack.BloodSim: BloodSim - 1.3.1.0: - Restructured simulation log back end to something less stupid to drastically reduce simulation time and memory usage - Removed a debug log entry that was left over from testing of 1.3.0.0 - Fixed a rounding and calculation error with Haste rating - Added option for Rune of SwordshatteringDbDocument: DbDoc Initial Version: DbDoc Initial versionASP .NET MVC CMS (Content Management System): Atomic CMS 2.1.2: Atomic CMS 2.1.2 release notes Atomic CMS installation guide Kind Of Magic MSBuild Task: Beta 4: Update to keep up with latest bug fixes. To those who don't like Magic/NoMagic attributes, you may change these names in KindOfMagic.targets file: Change this line: <MagicTask Assembly="@(IntermediateAssembly)" References="@(ReferencePath)"/> to something like this: <MagicTask Assembly="@(IntermediateAssembly)" References="@(ReferencePath)" MagicAttribute="MyMagicAttribute" NoMagicAttribute="MyNoMagicAttribute"/>N2 CMS: 2.1: N2 is a lightweight CMS framework for ASP.NET. It helps you build great web sites that anyone can update. Major Changes Support for auto-implemented properties ({get;set;}, based on contribution by And Poulsen) All-round improvements and bugfixes File manager improvements (multiple file upload, resize images to fit) New image gallery Infinite scroll paging on news Content templates First time with N2? Try the demo site Download one of the template packs (above) and open the proj...Wii Backup Fusion: Wii Backup Fusion 1.0: - Norwegian translation - French translation - German translation - WBFS dump for analysis - Scalable full HQ cover - Support for log file - Load game images improved - Support for image splitting - Diff for images after transfer - Support for scrubbing modes - Search functionality for log - Recurse depth for Files/Load - Show progress while downloading game cover - Supports more databases for cover download - Game cover loading routines improvedAutoLoL: AutoLoL v1.5.1: Fix: Fixed a bug where pressing Save As would not select the Mastery Directory by default Unexpected errors are now always reported to the user before closing AutoLoL down.* Extracted champion data to Data directory** Added disclaimer to notify users this application has nothing to do with Riot Games Inc. Updated Codeplex image * An error report will be shown to the user which can help the developers to find out what caused the error, this should improve support ** We are working on ...TortoiseHg: TortoiseHg 1.1.8: TortoiseHg 1.1.8 is a minor bug fix release, with minor improvementsBlogEngine.NET: BlogEngine.NET 2.0: Get DotNetBlogEngine for 3 Months Free! Click Here for More Info 3 Months FREE – BlogEngine.NET Hosting – Click Here! If you want to set up and start using BlogEngine.NET right away, you should download the Web project. If you want to extend or modify BlogEngine.NET, you should download the source code. If you are upgrading from a previous version of BlogEngine.NET, please take a look at the Upgrading to BlogEngine.NET 2.0 instructions. To get started, be sure to check out our installatio...Free Silverlight & WPF Chart Control - Visifire: Visifire SL and WPF Charts v3.6.6 Released: Hi, Today we are releasing final version of Visifire, v3.6.6 with the following new feature: * TextDecorations property is implemented in Title for Chart. * TitleTextDecorations property is implemented in Axis. * MinPointHeight property is now applicable for Column and Bar Charts. Also this release includes few bug fixes: * ToolTipText property of DataSeries was not getting applied from Style. * Chart threw exception if IndicatorEnabled property was set to true and Too...StyleCop Compliant Visual Studio Code Snippets: Visual Studio Code Snippets - January 2011: StyleCop Compliant Visual Studio Code Snippets Visual Studio 2010 provides C# developers with 38 code snippets, enhancing developer productivty and increasing the consistency of the code. Within this project the original code snippets have been refactored to provide StyleCop compliant versions of the original code snippets while also adding many new code snippets. Within the January 2011 release you'll find 82 code snippets to make you more productive and the code you write more consistent!...WPF Application Framework (WAF): WPF Application Framework (WAF) 2.0.0.2: Version: 2.0.0.2 (Milestone 2): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Remark The sample applications are using Microsoft’s IoC container MEF. However, the WPF Application Framework (WAF) doesn’t force you to use the same IoC container in your application. You can use ...DocX: DocX v1.0.0.11: Building Examples projectTo build the Examples project, download DocX.dll and add it as a reference to the project. OverviewThis version of DocX contains many bug fixes, it is a serious step towards a stable release. Added1) Unit testing project, 2) Examples project, 3) To many bug fixes to list here, see the source code change list history.Cosmos (C# Open Source Managed Operating System): 71406: This is the second release supporting the full line of Visual Studio 2010 editions. Changes since release 71246 include: Debug info is now stored in a single .cpdb file (which is a Firebird database) Keyboard input works now (using Console.ReadLine) Console colors work (using Console.ForegroundColor and .BackgroundColor)Paint.NET PSD Plugin: 1.6.0: Handling of layer masks has been greatly improved. Improved reliability. Many PSD files that previously loaded in as garbage will now load in correctly. Parallelized loading. PSD files containing layer masks will load in a bit quicker thanks to the removal of the sequential bottleneck. Hidden layers are no longer made visible on save. Many thanks to the users who helped expose the layer masks problem: Rob Horowitz, M_Lyons10. Please keep sending in those bug reports and PSD repro files!New Projects3D SharePoint Tag Cloud in Silverlight: This is a Silverlight Tag Cloud intended for use in SharePoint but can be configured for use separately as well. Based on a blog post from Peter Gerritsen (http://blog.petergerritsen.nl/2009/02/14/creating-a-3d-tagcloud-in-silverlight-part-1/).AffinityUI for Unity 3D: AffinityUI makes writing GUI code for Unity 3D easier with a component based API that allows you to write GUIs in a declarative fashion using a fluent interface, update events and powerful two-way databinding. A visual editor and scene GUI support are planned for the future.calendar synchronization: This will enable tight integration between ivvy core and infragistics scheduler. Will utilize oData and native isolated strorage instead of SQLite as planed earlier.Card Games Library: The aim of this project is to offer a framework for creating card games logics and rules. This project is not focused on particular games but offers a felxible and extensible base for creating card games, like; poker, solitaire, rummy, etcDbDocument: DbDoc tool seeks to be helper tool side by side with MS SQL server management studio tool, you can design your DB Tables in visualized way through Diagrams and then use “DbDoc” tool to generate design document in MS Word table formatDelux: Delux project for educationDnEcuDiag - A .NET Ecu Diagnostic Application: DnEcuDiag is an application framework for developing electronic control unit diagnostic functionality without the need to implement code.Dynamics CRM 4.0 Recycle Bin: This add-on for Microsoft Dynamics CRM 4.0 to enable Recycle Bin Features (Restore, Permenant Delete) for CRM users.EPPLib.it: Il sistema sincrono di registrazione e mantenimento dei nomi a dominio del Registro.it utilizza il protocollo EPP (Extensible Provisioning Protocol). EPPLib consente di interfacciare i propri progetti con il sistema sincrono del Registro.it.IoC4Fun: Very LightWeight IoC or DI Container only required Net Framework 3.5 written in C#. For Small Apps or Educational purpose. Not intrusion code added like others Containers. Just Plan Register Dependencies and Let Container resolve magically the Injection Dependencies.ISocial: WP7 Application, centralise les réseaux sociauxJohnnyIssa: begASP.NET Version 4.LiveCPE: LiveCPE is an Academic project based on C# and ASP.Net. It aims to be a social network website. MS CRM - Skype Connector: Skype Addon for Microsoft Dynamics CRM allows to dial CRM Contacts, Lead and so on via Skype. It's developed in ASP.NET and C#.Ryan's Projects: a group of random c# projectsSeleniuMspec: SeleniuMspec is a template for Selenium IDE that generates Selenium tests for Mspec (a .NET BDD framework). SharePoint FAQ Web Part: The SharePoint FAQ Web Part makes it easier for SharePoint Users to display FAQs feature on their SharePoint sites. You'll no longer have to maintain HTML and anchors in the Content Editor Web Part, as the FAQs are now automatically generated from a SharePoint list. Silverlight Planet: Projetos da comunidade Silverlight Planet www.silverlightplanet.net.brWP7 Expense Report: Expense Report for Windows Phone 7xll - the easy way to create Excel add-ins: The xll C++ library makes it easy to create xll add-ins for Excel. It also supports the big grid, wide-character strings, and thread-safe functions. ????????: ????,??,??,????,????,??????

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  • CodePlex Daily Summary for Tuesday, March 01, 2011

    CodePlex Daily Summary for Tuesday, March 01, 2011Popular ReleasesDirectQ: Release 1.8.7 (Beta 3): Fixes some problems and adds some more enhancements.Sandcastle Help File Builder: SHFB v1.9.2.0 Release: NOTE TO 32-BIT WINDOWS XP USERS: There is a problem with a type converter that fails on 32-bit Windows XP due to how it searches for the framework versions. I'll issue an update later today that fixes the issue. This release supports the Sandcastle June 2010 Release (v2.6.10621.1). It includes full support for generating, installing, and removing MS Help Viewer files. This new release is compiled under .NET 4.0, supports Visual Studio 2010 solutions and projects as documentation sources, ...Network Monitor Open Source Parsers: Microsoft Network Monitor Parsers 3.4.2554: The Network Monitor Parsers packages contain parsers for more than 400 network protocols, including RFC based public protocols and protocols for Microsoft products defined in the Microsoft Open Specifications for Windows and SQL Server. NetworkMonitor_Parsers.msi is the base parser package which defines parsers for commonly used public protocols and protocols for Microsoft Windows. In this release, we have added 4 new protocol parsers and updated 79 existing parsers in the NetworkMonitor_Pa...Ajax Minifier: Microsoft Ajax Minifier 4.13: New features: switches and settings for turning off Conditional Compilation comment processing; for adding variable and/or function names that should not be renamed automatically; for adding manual renaming of variables/functions/properties; for automatic evaluation of certain literal expressions (but not all).Image Resizer for Windows: Image Resizer 3 Preview 1: Prepare to have your minds blown. This is the first preview of what will eventually become 39613. There are still a lot of rough edges and plenty of areas still under construction, but for your basic needs, it should be relativly stable. Note: You will need the .NET Framework 4 installed to use this version. Below is a status report of where this release is in terms of the overall goal for version 3. If you're feeling a bit technically ambitious and want to check out some of the features th...JSON Toolkit: JSON Toolkit 1.1: updated GetAllJsonObjects() method and GetAllProperties() methods to JsonObject and Properties propertiesFacebook Graph Toolkit: Facebook Graph Toolkit 1.0: Refer to http://computerbeacon.net for Documentation and Tutorial New features:added FQL support added Expires property to Api object added support for publishing to a user's friend / Facebook Page added support for posting and removing comments on posts added support for adding and removing likes on posts and comments added static methods for Page class added support for Iframe Application Tab of Facebook Page added support for obtaining the user's country, locale and age in If...ASP.NET MVC Project Awesome, jQuery Ajax helpers (controls): 1.7.1: A rich set of helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager small improvements for some helpers and AjaxDropdown has Data like the Lookup except it's value gets reset and list refilled if any element from data gets changedManaged Extensibility Framework: MEF 2 Preview 3: This release aims .net 4.0 and Silverlight 4.0. Accordingly, there are two solutions files. The assemblies are named System.ComponentModel.Composition.Codeplex.dll as a way to avoid clashing with the version shipped with the 4th version of the framework. Introduced CompositionOptions to container instantiation CompositionOptions.DisableSilentRejection makes MEF throw an exception on composition errors. Useful for diagnostics Support for open generics Support for attribute-less registr...PHPExcel: PHPExcel 1.7.6 Production: DonationsDonate via PayPal via PayPal. If you want to, we can also add your name / company on our Donation Acknowledgements page. PEAR channelWe now also have a full PEAR channel! Here's how to use it: New installation: pear channel-discover pear.pearplex.net pear install pearplex/PHPExcel Or if you've already installed PHPExcel before: pear upgrade pearplex/PHPExcel The official page can be found at http://pearplex.net. Want to contribute?Please refer the Contribute page.WPF Application Framework (WAF): WPF Application Framework (WAF) 2.0.0.4: Version: 2.0.0.4 (Milestone 4): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Remark The sample applications are using Microsoft’s IoC container MEF. However, the WPF Application Framework (WAF) doesn’t force you to use the same IoC container in your application. You can use ...VidCoder: 0.8.2: Updated auto-naming to handle seconds and frames ranges as well. Deprecated the {chapters} token for auto-naming in favor of {range}. Allowing file drag to preview window and enabling main window shortcut keys to work no matter what window is focused. Added option in config to enable giving custom names to audio tracks. (Note that these names will only show up certain players like iTunes or on the iPod. Players that support custom track names normally may not show them.) Added tooltips ...SQL Server Compact Toolbox: Standalone version 2.0 for SQL Server Compact 4.0: Download the Visual Studio add-in for SQL Server Compact 4.0 and 3.5 from here Standalone version of (most of) the same functionality as the add-in, for SQL Server Compact 4.0. Useful for anyone not having Visual Studio Professional or higher installed. Requires .NET 4.0. Any feedback much appreciated.Claims Based Identity & Access Control Guide: Drop 1 - Claims Identity Guide V2: Highlights of drop #1 This is the first drop of the new "Claims Identity Guide" edition. In this release you will find: All previous samples updated and enhanced. All code upgraded to .NET 4 and Visual Studio 2010. Extensive cleanup. Refactored Simulated Issuers: each solution now gets its own issuers. This results in much cleaner and simpler to understand code. Added Single Sign Out support. Added first sample using ACS ("ACS as a Federation Provider"). This sample extends the ori...Simple Notify: Simple Notify Beta 2011-02-25: Feature: host the service with a single click in console Feature: host the service as a windows service Feature: notification cient application Feature: push client application Feature: push notifications from your powershell script Feature: C# wrapper libraries for your applicationspatterns & practices: Project Silk: Project Silk Community Drop 3 - 25 Feb 2011: IntroductionWelcome to the third community drop of Project Silk. For this drop we are requesting feedback on overall application architecture, code review of the JavaScript Conductor and Widgets, and general direction of the application. Project Silk provides guidance and sample implementations that describe and illustrate recommended practices for building modern web applications using technologies such as HTML5, jQuery, CSS3 and Internet Explorer 9. This guidance is intended for experien...Minemapper: Minemapper v0.1.5: Now supports new Minecraft beta v1.3 map format, thanks to updated mcmap. Disabled biomes, until Minecraft Biome Extractor supports new format.HERB.IQ: HERB.IQ.NEW.INSTALL.0.6.0.zip: HERB.IQ.NEW.INSTALL.0.6.0.zipCoding4Fun Tools: Coding4Fun.Phone.Toolkit v1.2: New control, Toast Prompt! Removed progress bar since Silverlight Toolkit Feb 2010 has it.HubbleDotNet - Open source full-text search engine: V1.1.0.0: Add Sqlite3 DBAdapter Add App Report when Query Cache is Collecting. Improve the performance of index through Synchronize. Add top 0 feature so that we can only get count of the result. Improve the score calculating algorithm of match. Let the score of the record that match all items large then others. Add MySql DBAdapter Improve performance for multi-fields sort . Using hash table to access the Payload data. The version before used bin search. Using heap sort instead of qui...New ProjectsAssembly Explorer: Assembly Explorer is a developer utility that displays the namespaces, types, and members in an assembly. It also displays the MSIL or translated .NET language code.automated reporting system: ???????? ??????????? ?????????????? ???????????????? ????????? ?????? ?????????? ????????? Custom XSLT with Group by in Biztalk 2009: Custom XSLT with Group by in Biztalk 2009DotNet Repository: A simple to use, generic repository using Linq to SQL or Linq to Objects. euler 28: euler 28euler29: euler 29 problemFreeType for AirplaySDK: FreeType adoptation for Airplay SDK.Icicle Framework: An in-the-works component based game framework for XNA.Jogo dos Palitinhos: Jogo desenvolvido por alunos do 4º Ciclo Noturno de Programação do Curso de Análise de Sistemas e Tecnologia da Informação da Faculdade de Tecnologia de Carapicuíba. Este é o jogo dos palitinhos: uma mistura de lógica, advinhação e sorte. Será desenvolvido na plataforma Java.karmencita: Karmencita is a high level object query language for .NET . Its purpose is to allow easy querying from in memory structured data.Libero Site 011: libero sit 011MaLoRTLib: raytracer library used in the MaLoRT.MetroEdit: A WPF Text Editor based on the Metro UI Design Guidelines. Features: - Clean and simple UI based on Metro - 32bit and 64bit support - Tabbing - Syntax highlighting NOTE: Based on .NET Framework 4.0 and uses the following libraries: - MVVM Light Toolkit - AvalonEditMiaSocks: A .NET SOCKS Server Implementation base on SuperSocketmicroruntime: The MicroRuntime project is a .NET utility library.MVC Forum: A bulletin board system (like phpBB) running on ASP.NET MVC.newshehuishijianzhongxin: newshehuishijianzhongxinPrism Extension: Contains extensions for prism to reinforce some functionsRInterfaces: An interface to pass data toward and back from R and executing R code from .NETSharePoint 2007 Wiki Export: A very simple wiki export utility for SharePoint 2007. You can export a wiki library to the file system with the specified file extension, and wrapped in the speciified markup. Written in C#. The List service url is set dynamically so there is a dummy url in the configurations.Simon Squared: Simon Squared is a Multi-player Puzzle game for Windows Phone 7. It uses the XNA framework on the Phone, and the WCF Http CTP on the server side to handle communication between phones. It's written in C#.Sitefinity Toolkit: The Sitefinity Toolkit is a collection of enhancements to the Sitefinity Content Management System by Telerik. It currently supports Sitefinity version 3.7 (through SP4), and includes a number of tools to automate and simplify a number of actions and features.Slog: Slog is blog engine like Wordpress in Silverlight 4 that will have same fonctionality to bigin with and the same extensiblity thanks to MEF. Server side will be WCF DataServices, Entity Framework 4 and SQL Server Compact 4.SnagL: Social Network Analysis Graph Live (SnagL) is a light-weight, pluggable application that operates from a web browser and works with existing applications and back-end data stores to provide a visual way to understand information and enhance analysis.SocialShare Starter Kit: SocialShare Starter Kit is a web application that illustrate a wide range of features that needed to build a social site.This web application framework written in C# ASP.NET 4.0.Split Large XML file into small XML files: Split Large XML file into group of smaller XML files in sequential order. As posted to http://codeproject.com <a href='http://www.codeproject.com/KB/XML/SplitLargeXMLintoSmallFil.aspx'>Link</a>SSIS SSH Components: SSIS control flow tasks for SFTP and executing shell commands along with an SSH connection manager.StudioShell: StudioShell is a deeply integrated PowerShell module for Visual Studio 2010 and 2008. It will change the way you interact with your IDE and code by exposing the IDE extensibility features to PowerShell. What once took a binary can now be done in a one-liner.TBS: TBS TEZ BILGI SISTEMI tez bilgi sistemiuTestingService: uTestingService is a webservice with wrappers around Node and Document to allow for end-end testing of UmbracoWebsite Panel: Website Panel is a Windows application to help you manage multiple Dotnetnuke applications. Easy installations, backups & upgrades of DNN websites are just a few features of this application. Zinc: Zinc is a utility library for ASP.NET web forms development. It has support for: - utility methods for working easier with controls - CSV exports - HttpModules for dealing with caching and path based rights. - custom controls This library runs on .NET 2.0 and i would like to kee

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  • MERGE Bug with Filtered Indexes

    - by Paul White
    A MERGE statement can fail, and incorrectly report a unique key violation when: The target table uses a unique filtered index; and No key column of the filtered index is updated; and A column from the filtering condition is updated; and Transient key violations are possible Example Tables Say we have two tables, one that is the target of a MERGE statement, and another that contains updates to be applied to the target.  The target table contains three columns, an integer primary key, a single character alternate key, and a status code column.  A filtered unique index exists on the alternate key, but is only enforced where the status code is ‘a’: CREATE TABLE #Target ( pk integer NOT NULL, ak character(1) NOT NULL, status_code character(1) NOT NULL,   PRIMARY KEY (pk) );   CREATE UNIQUE INDEX uq1 ON #Target (ak) INCLUDE (status_code) WHERE status_code = 'a'; The changes table contains just an integer primary key (to identify the target row to change) and the new status code: CREATE TABLE #Changes ( pk integer NOT NULL, status_code character(1) NOT NULL,   PRIMARY KEY (pk) ); Sample Data The sample data for the example is: INSERT #Target (pk, ak, status_code) VALUES (1, 'A', 'a'), (2, 'B', 'a'), (3, 'C', 'a'), (4, 'A', 'd');   INSERT #Changes (pk, status_code) VALUES (1, 'd'), (4, 'a');          Target                     Changes +-----------------------+    +------------------+ ¦ pk ¦ ak ¦ status_code ¦    ¦ pk ¦ status_code ¦ ¦----+----+-------------¦    ¦----+-------------¦ ¦  1 ¦ A  ¦ a           ¦    ¦  1 ¦ d           ¦ ¦  2 ¦ B  ¦ a           ¦    ¦  4 ¦ a           ¦ ¦  3 ¦ C  ¦ a           ¦    +------------------+ ¦  4 ¦ A  ¦ d           ¦ +-----------------------+ The target table’s alternate key (ak) column is unique, for rows where status_code = ‘a’.  Applying the changes to the target will change row 1 from status ‘a’ to status ‘d’, and row 4 from status ‘d’ to status ‘a’.  The result of applying all the changes will still satisfy the filtered unique index, because the ‘A’ in row 1 will be deleted from the index and the ‘A’ in row 4 will be added. Merge Test One Let’s now execute a MERGE statement to apply the changes: MERGE #Target AS t USING #Changes AS c ON c.pk = t.pk WHEN MATCHED AND c.status_code <> t.status_code THEN UPDATE SET status_code = c.status_code; The MERGE changes the two target rows as expected.  The updated target table now contains: +-----------------------+ ¦ pk ¦ ak ¦ status_code ¦ ¦----+----+-------------¦ ¦  1 ¦ A  ¦ d           ¦ <—changed from ‘a’ ¦  2 ¦ B  ¦ a           ¦ ¦  3 ¦ C  ¦ a           ¦ ¦  4 ¦ A  ¦ a           ¦ <—changed from ‘d’ +-----------------------+ Merge Test Two Now let’s repopulate the changes table to reverse the updates we just performed: TRUNCATE TABLE #Changes;   INSERT #Changes (pk, status_code) VALUES (1, 'a'), (4, 'd'); This will change row 1 back to status ‘a’ and row 4 back to status ‘d’.  As a reminder, the current state of the tables is:          Target                        Changes +-----------------------+    +------------------+ ¦ pk ¦ ak ¦ status_code ¦    ¦ pk ¦ status_code ¦ ¦----+----+-------------¦    ¦----+-------------¦ ¦  1 ¦ A  ¦ d           ¦    ¦  1 ¦ a           ¦ ¦  2 ¦ B  ¦ a           ¦    ¦  4 ¦ d           ¦ ¦  3 ¦ C  ¦ a           ¦    +------------------+ ¦  4 ¦ A  ¦ a           ¦ +-----------------------+ We execute the same MERGE statement: MERGE #Target AS t USING #Changes AS c ON c.pk = t.pk WHEN MATCHED AND c.status_code <> t.status_code THEN UPDATE SET status_code = c.status_code; However this time we receive the following message: Msg 2601, Level 14, State 1, Line 1 Cannot insert duplicate key row in object 'dbo.#Target' with unique index 'uq1'. The duplicate key value is (A). The statement has been terminated. Applying the changes using UPDATE Let’s now rewrite the MERGE to use UPDATE instead: UPDATE t SET status_code = c.status_code FROM #Target AS t JOIN #Changes AS c ON t.pk = c.pk WHERE c.status_code <> t.status_code; This query succeeds where the MERGE failed.  The two rows are updated as expected: +-----------------------+ ¦ pk ¦ ak ¦ status_code ¦ ¦----+----+-------------¦ ¦  1 ¦ A  ¦ a           ¦ <—changed back to ‘a’ ¦  2 ¦ B  ¦ a           ¦ ¦  3 ¦ C  ¦ a           ¦ ¦  4 ¦ A  ¦ d           ¦ <—changed back to ‘d’ +-----------------------+ What went wrong with the MERGE? In this test, the MERGE query execution happens to apply the changes in the order of the ‘pk’ column. In test one, this was not a problem: row 1 is removed from the unique filtered index by changing status_code from ‘a’ to ‘d’ before row 4 is added.  At no point does the table contain two rows where ak = ‘A’ and status_code = ‘a’. In test two, however, the first change was to change row 1 from status ‘d’ to status ‘a’.  This change means there would be two rows in the filtered unique index where ak = ‘A’ (both row 1 and row 4 meet the index filtering criteria ‘status_code = a’). The storage engine does not allow the query processor to violate a unique key (unless IGNORE_DUP_KEY is ON, but that is a different story, and doesn’t apply to MERGE in any case).  This strict rule applies regardless of the fact that if all changes were applied, there would be no unique key violation (row 4 would eventually be changed from ‘a’ to ‘d’, removing it from the filtered unique index, and resolving the key violation). Why it went wrong The query optimizer usually detects when this sort of temporary uniqueness violation could occur, and builds a plan that avoids the issue.  I wrote about this a couple of years ago in my post Beware Sneaky Reads with Unique Indexes (you can read more about the details on pages 495-497 of Microsoft SQL Server 2008 Internals or in Craig Freedman’s blog post on maintaining unique indexes).  To summarize though, the optimizer introduces Split, Filter, Sort, and Collapse operators into the query plan to: Split each row update into delete followed by an inserts Filter out rows that would not change the index (due to the filter on the index, or a non-updating update) Sort the resulting stream by index key, with deletes before inserts Collapse delete/insert pairs on the same index key back into an update The effect of all this is that only net changes are applied to an index (as one or more insert, update, and/or delete operations).  In this case, the net effect is a single update of the filtered unique index: changing the row for ak = ‘A’ from pk = 4 to pk = 1.  In case that is less than 100% clear, let’s look at the operation in test two again:          Target                     Changes                   Result +-----------------------+    +------------------+    +-----------------------+ ¦ pk ¦ ak ¦ status_code ¦    ¦ pk ¦ status_code ¦    ¦ pk ¦ ak ¦ status_code ¦ ¦----+----+-------------¦    ¦----+-------------¦    ¦----+----+-------------¦ ¦  1 ¦ A  ¦ d           ¦    ¦  1 ¦ d           ¦    ¦  1 ¦ A  ¦ a           ¦ ¦  2 ¦ B  ¦ a           ¦    ¦  4 ¦ a           ¦    ¦  2 ¦ B  ¦ a           ¦ ¦  3 ¦ C  ¦ a           ¦    +------------------+    ¦  3 ¦ C  ¦ a           ¦ ¦  4 ¦ A  ¦ a           ¦                            ¦  4 ¦ A  ¦ d           ¦ +-----------------------+                            +-----------------------+ From the filtered index’s point of view (filtered for status_code = ‘a’ and shown in nonclustered index key order) the overall effect of the query is:   Before           After +---------+    +---------+ ¦ pk ¦ ak ¦    ¦ pk ¦ ak ¦ ¦----+----¦    ¦----+----¦ ¦  4 ¦ A  ¦    ¦  1 ¦ A  ¦ ¦  2 ¦ B  ¦    ¦  2 ¦ B  ¦ ¦  3 ¦ C  ¦    ¦  3 ¦ C  ¦ +---------+    +---------+ The single net change there is a change of pk from 4 to 1 for the nonclustered index entry ak = ‘A’.  This is the magic performed by the split, sort, and collapse.  Notice in particular how the original changes to the index key (on the ‘ak’ column) have been transformed into an update of a non-key column (pk is included in the nonclustered index).  By not updating any nonclustered index keys, we are guaranteed to avoid transient key violations. The Execution Plans The estimated MERGE execution plan that produces the incorrect key-violation error looks like this (click to enlarge in a new window): The successful UPDATE execution plan is (click to enlarge in a new window): The MERGE execution plan is a narrow (per-row) update.  The single Clustered Index Merge operator maintains both the clustered index and the filtered nonclustered index.  The UPDATE plan is a wide (per-index) update.  The clustered index is maintained first, then the Split, Filter, Sort, Collapse sequence is applied before the nonclustered index is separately maintained. There is always a wide update plan for any query that modifies the database. The narrow form is a performance optimization where the number of rows is expected to be relatively small, and is not available for all operations.  One of the operations that should disallow a narrow plan is maintaining a unique index where intermediate key violations could occur. Workarounds The MERGE can be made to work (producing a wide update plan with split, sort, and collapse) by: Adding all columns referenced in the filtered index’s WHERE clause to the index key (INCLUDE is not sufficient); or Executing the query with trace flag 8790 set e.g. OPTION (QUERYTRACEON 8790). Undocumented trace flag 8790 forces a wide update plan for any data-changing query (remember that a wide update plan is always possible).  Either change will produce a successfully-executing wide update plan for the MERGE that failed previously. Conclusion The optimizer fails to spot the possibility of transient unique key violations with MERGE under the conditions listed at the start of this post.  It incorrectly chooses a narrow plan for the MERGE, which cannot provide the protection of a split/sort/collapse sequence for the nonclustered index maintenance. The MERGE plan may fail at execution time depending on the order in which rows are processed, and the distribution of data in the database.  Worse, a previously solid MERGE query may suddenly start to fail unpredictably if a filtered unique index is added to the merge target table at any point. Connect bug filed here Tests performed on SQL Server 2012 SP1 CUI (build 11.0.3321) x64 Developer Edition © 2012 Paul White – All Rights Reserved Twitter: @SQL_Kiwi Email: [email protected]

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  • CodePlex Daily Summary for Tuesday, June 21, 2011

    CodePlex Daily Summary for Tuesday, June 21, 2011Popular ReleasesESRI ArcGIS Silverlight Toolkit: June 2011 - v2.2: ESRI ArcGIS Silverlight Toolkit v2.2 New controls added: Attribution Control ScaleLine Control GpsLayer (WinPhone only)Terraria World Viewer: Version 1.4: Update June 21st World file will be stored in memory to minimize chances of Terraria writing to it while we read it. Different set of APIs allow the program to draw the world much quicker. Loading world information (world variables, chest list) won't cause the GUI to freeze at all anymore. Re-introduced the "Filter chests" checkbox: Allow disabling of chest filter/finder so all chest symbos are always drawn. First-time users will have a default world path suggested to them: C:\Users\U...AcDown????? - Anime&Comic Downloader: AcDown????? v3.0 Beta7: ??AcDown???????????????,?????????????????????。????????????????????,??Acfun、Bilibili、???、???、?????,???????????、???????。 AcDown???????????????????????????,???,???????????????????。 AcDown???????C#??,?????"Acfun?????"。 ????32??64? Windows XP/Vista/7 ????????????? ??:????????Windows XP???,?????????.NET Framework 2.0???(x86)?.NET Framework 2.0???(x64),?????"?????????"??? ??????????????,??????????: ??"AcDown?????"????????? ??v3.0 Beta7 ????????????? ???? ?? ????????????????? "??????"?????"?...BlogEngine.NET: BlogEngine.NET 2.5 RC: BlogEngine.NET Hosting - Click Here! 3 Months FREE – BlogEngine.NET Hosting – Click Here! This is a Release Candidate version for BlogEngine.NET 2.5. The most current, stable version of BlogEngine.NET is version 2.0. Find out more about the BlogEngine.NET 2.5 RC here. If you want to extend or modify BlogEngine.NET, you should download the source code. To get started, be sure to check out our installation documentation. If you are upgrading from a previous version, please take a look at ...Microsoft All-In-One Code Framework - a centralized code sample library: All-In-One Code Framework 2011-06-19: Alternatively, you can install Sample Browser or Sample Browser VS extension, and download the code samples from Sample Browser. Improved and Newly Added Examples:For an up-to-date code sample index, please refer to All-In-One Code Framework Sample Catalog. NEW Samples for Windows Azure Sample Description Owner CSAzureStartupTask The sample demonstrates using the startup tasks to install the prerequisites or to modify configuration settings for your environment in Windows Azure Rafe Wu ...Facebook C# SDK: 5.0.40: This is a RTW release which adds new features to v5.0.26 RTW. Support for multiple FacebookMediaObjects in one request. Allow FacebookMediaObjects in batch requests. Removes support for Cassini WebServer (visual studio inbuilt web server). Better support for unit testing and mocking. updated SimpleJson to v0.6 Refer to CHANGES.txt for details. For more information about this release see the following blog posts: Facebook C# SDK - Multiple file uploads in Batch Requests Faceb...NLog - Advanced .NET Logging: NLog 2.0 Release Candidate: Release notes for NLog 2.0 RC can be found at http://nlog-project.org/nlog-2-rc-release-notesPowerGUI Visual Studio Extension: PowerGUI VSX 1.3.5: Changes - VS SDK no longer required to be installed (a bug in v. 1.3.4).Gendering Add-In for Microsoft Office Word 2010: Gendering Add-In: This is the first stable Version of the Gendering Add-In. Unzip the package and start "setup.exe". The .reg file shows how to config an alternate path for suggestion table.Intelligent Enterprise Solution: Document for this project: Document for this projectTerrariViewer: TerrariViewer v3.1 [Terraria Inventory Editor]: This version adds tool tips. Almost every picture box you mouse over will tell you what item is in that box. I have also cleaned up the GUI a little more to make things easier on my end. There are various bug fixes including ones associated with opening different characters in the same instance of the program. As always, please bring any bugs you find to my attention.Kinect Paint: KinectPaint V1.0: This is version 1.0 of Kinect Paint. To run it, follow the steps: Install the Kinect SDK for Windows (available at http://research.microsoft.com/en-us/um/redmond/projects/kinectsdk/download.aspx) Connect your Kinect device to the computer and to the power. Download the Zip file. Unblock the Zip file by right clicking on it, and pressing the Unblock button in the file properties (if available). Extract the content of the Zip file. Run KinectPaint.exe.CommonLibrary.NET: CommonLibrary.NET - 0.9.7 Beta: A collection of very reusable code and components in C# 3.5 ranging from ActiveRecord, Csv, Command Line Parsing, Configuration, Holiday Calendars, Logging, Authentication, and much more. Samples in <root>\src\Lib\CommonLibrary.NET\Samples CommonLibrary.NET 0.9.7Documentation 6738 6503 New 6535 Enhancements 6583 6737DropBox Linker: DropBox Linker 1.2: Public sub-folders are now monitored for changes as well (thanks to mcm69) Automatic public sync folder detection (thanks to mcm69) Non-Latin and special characters encoded correctly in URLs Pop-ups are now slot-based (use first free slot and will never be overlapped — test it while previewing timeout) Public sync folder setting is hidden when auto-detected Timeout interval is displayed in popup previews A lot of major and minor code refactoring performed .NET Framework 4.0 Client...MVC Controls Toolkit: Mvc Controls Toolkit 1.1.5 RC: Added Extended Dropdown allows a prompt item to be inserted as first element. RequiredAttribute, if present, trggers if no element is chosen Client side javascript function to set/get the values of DateTimeInput, TypedTextBox, TypedEditDisplay, and to bind/unbind a "change" handler The selected page in the pager is applied the attribute selected-page="selected" that can be used in the definition of CSS rules to style the selected page items controls now interpret a null value as an empr...Umbraco CMS: Umbraco CMS 5.0 CTP 1: Umbraco 5 Community Technology Preview Umbraco 5 will be the next version of everyone's favourite, friendly ASP.NET CMS that already powers over 100,000 websites worldwide. Try out our first CTP of version 5 today! If you're new to Umbraco and would like to get a quick low-down on our popular and easy-to-learn approach to content management, check out our intro video here. What's in the v5 CTP box? This is a preview version of version 5 and includes support for the following familiar Umbr...LevelZap: 1.0: Initial version. Zap away!Ribbon Browser for Microsoft Dynamics CRM 2011: Ribbon Browser (1.0.514.30): Initial releaseCoding4Fun Kinect Toolkit: Coding4Fun.Kinect Toolkit: Version 1.0Kinect Mouse Cursor: Kinect Mouse Cursor v1.0: The initial release of the Kinect Mouse Cursor project!New ProjectsBaffoHat Kinect: BaffHat is a game for fun with friends and drink a little.Bango Windows Phone 7 Application Analytics SDK: Bango application analytics is an analytics solution for mobile applications. This SDK provides a framework you can use in your application to add analytics capabilities to your mobile applications. It's developed in C#.NET (4.0) and targets the Windows Phone 7 operating system.C++ Winsock WebSocket server: A websockets server built in C++ using the C APIs Winsock and <windows.h>. Works with the current version of Chrome (13.0.782.24).Core.Cpp: CORE-CPPDataContractJson ValueProviderFactory: ValueProviderFactory for ASP.NET MVC that uses the DataContractJsonSerializer for JSON Serialization. This comes in handy when porting RESTful JSON Services from WCF to ASP.NET MVC.E4D CRM 2011 Ribbon Utility: E4D CRM 2011 Ribbon Utility helps you speed Dynamics CRM 2011 Ribbon customization. Ribbon customization tasks can be exhausting, as it require many iterations, mouse clicks and input. This utility does the heavy lifting for you: it will zip, upload and publish automatically!EASY: Eve Application Service for YoueGlass: eGlassGrove SMTP Mailer: Grove SMTP Mailer is a Simple and Open Source SMTP E-Mail Sender Written in Visual Basic by Hommerhart - Effect-7 Grove SMTP Mailer on SourceForge : https://sourceforge.net/projects/grovesmtpmailer/hoox: PHP/MySQL CMS focused on speed and simplicity over feature-diversity.Intelligent Enterprise Solution: An ERP source code,including sample,demo,tool.documentKinect Touch Device: A simple "WPF4 Touch Device" using Kinect with OpenNI & NITE (written in C#). This project makes it easy to transform your WPF4 touch application in "touch less" with the Kinect with little change : replace "Window" base class by "KinectWindow". Currently the Touch Down and Touch Up is determined by the distance of the hand from the Kinect. A possible change would be to detect if the hand is open or closed to enable the Touch Down or Touch Up.kinectPainter: kinect paint projectLiteQuery: Lite Query is an implementation of the Query Object Pattern that will help you to build the queries in the Frontend layer in a way that will be independent from the ORM used in Data Access. The object is translated in the language of the ORM framework using Query Translators. This version comes with translators for Entity Framework and NHibernate.octoInstall: octoInstall is a fast and easy to operate installer and updater utility. For updating it uses a binary compare techology, that creates very small update packages to patch software from one version to another and saves up to 99% of update size.P7T_Engine: P7T_Engine makes it easier for developers to develop advanced 2D game and also basic 3D games. You'll no longer have to write your own engine for 2D games or write large chunks of code to make your project happen. The entire engine is developed in C++. LUA scripting ability is something that we are looking forward to.Panning Tile Control for Windows Phone 7: The panning tile control mimics the functionality of the Windows Phone 7 music tile: Photos and text slowly pan, scroll and fade. It can be used inside of any WP7 Silverlight app.PerstDemo: This project is to show the large amount of data, which is in the format of XML file on Window Phone 7 using Perst Database for this we convert XML to Perst. Due to large data, it consumes a lot of time in conversion & also if fire queries on the database. So, what can be done to lessen the time consumed. Please, download the project http://perstdemo.codeplex.com/releases/view/68640 and have a look. Waiting for the response, ideas, suggestions....SimplePaxos: Implement a simple paxos protocolSOL Polar Converter: Create optimized polars for Bluewater Racing and Expedition from Sailonline races or text polar dataStructured Web Data Extraction: The dataset used in SIGIR 2011 paperSurveyTemplate: This is just for practising the use of culteInfo class in c#Task Unlocker: A site level feature that provides UI for unclocking tasks locked by workflow upgrade. Why tasks get locked : Explanation of cause http://blogs.code-counsel.net/Wouter/Lists/Posts/Post.aspx?ID=118 Inspiration for this feature : Workaround code http://geek.hubkey.com/2007/09/locked-workflow.html Test Project kobi: just for testWindows Azure CDN Helpers: This is a project that helps you quickly utilize the Windows Azure CDN from your ASP.NET MVC website. These helpers will work on sites hosted on and off Windows Azure.WPF Breakout: Remake of the classic Breakout game using WPF. WPFRadio: a WPF Radio Web Player ...

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  • Using multiple column layout with HTML 5 and CSS 3

    - by nikolaosk
    This is going to be the fourth post in a series of posts regarding HTML 5. You can find the other posts here , here and here.In this post I will provide a hands-on example with HTML 5 and CSS 3 on how to create a page with multiple columns and proper layout.I will show you how to use CSS 3 to create columns much easier than relying on DIV elements and the float CSS rule.I will also show you how to use browser-specific prefix rules (-ms for Internet Explorer and -moz for Firefox ) for browsers that do not fully support CSS 3.In order to be absolutely clear this is not (and could not be) a detailed tutorial on HTML 5. There are other great resources for that.Navigate to the excellent interactive tutorials of W3School.Another excellent resource is HTML 5 Doctor.Two very nice sites that show you what features and specifications are implemented by various browsers and their versions are http://caniuse.com/ and http://html5test.com/. At this times Chrome seems to support most of HTML 5 specifications.Another excellent way to find out if the browser supports HTML 5 and CSS 3 features is to use the Javascript lightweight library Modernizr.In this hands-on example I will be using Expression Web 4.0.This application is not a free application. You can use any HTML editor you like.You can use Visual Studio 2012 Express edition. You can download it here.I will create a simple page with information about HTML 5, CSS 3 and JQuery. This is the full HTML 5 code. <!DOCTYPE html><html lang="en">  <head>    <title>HTML 5, CSS3 and JQuery</title>    <meta http-equiv="Content-Type" content="text/html;charset=utf-8" >    <link rel="stylesheet" type="text/css" href="style.css">       </head>  <body>    <div id="header">      <h1>Learn cutting edge technologies</h1>      <p>HTML 5, JQuery, CSS3</p>    </div>    <div id="main">      <div id="mainnews">        <div>          <h2>HTML 5</h2>        </div>        <div>          <p>            HTML5 is the latest version of HTML and XHTML. The HTML standard defines a single language that can be written in HTML and XML. It attempts to solve issues found in previous iterations of HTML and addresses the needs of Web Applications, an area previously not adequately covered by HTML.          </p>          <div class="quote">            <h4>Do More with Less</h4>            <p>             jQuery is a fast and concise JavaScript Library that simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development.             </p>            </div>          <p>            The HTML5 test(html5test.com) score is an indication of how well your browser supports the upcoming HTML5 standard and related specifications. Even though the specification isn't finalized yet, all major browser manufacturers are making sure their browser is ready for the future. Find out which parts of HTML5 are already supported by your browser today and compare the results with other browsers.                      The HTML5 test does not try to test all of the new features offered by HTML5, nor does it try to test the functionality of each feature it does detect. Despite these shortcomings we hope that by quantifying the level of support users and web developers will get an idea of how hard the browser manufacturers work on improving their browsers and the web as a development platform.</p>        </div>      </div>              <div id="CSS">        <div>          <h2>CSS 3 Intro</h2>        </div>        <div>          <p>          Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation semantics (the look and formatting) of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can also be applied to any kind of XML document, including plain XML, SVG and XUL.          </p>        </div>      </div>            <div id="CSSmore">        <div>          <h2>CSS 3 Purpose</h2>        </div>        <div>          <p>            CSS is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation, including elements such as the layout, colors, and fonts.[1] This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple pages to share formatting, and reduce complexity and repetition in the structural content (such as by allowing for tableless web design).          </p>        </div>      </div>                </div>    <div id="footer">        <p>Feel free to google more about the subject</p>      </div>     </body>  </html>  The markup is very easy to follow. I have used some HTML 5 tags and the relevant HTML 5 doctype.The CSS code (style.css) follows  body{        line-height: 30px;        width: 1024px;        background-color:#eee;      }            p{        font-size:17px;    font-family:"Comic Sans MS"      }      p,h2,h3,h4{        margin: 0 0 20px 0;      }            #main, #header, #footer{        width: 100%;        margin: 0px auto;        display:block;      }            #header{        text-align: center;         border-bottom: 1px solid #000;         margin-bottom: 30px;      }            #footer{        text-align: center;         border-top: 1px solid #000;         margin-bottom: 30px;      }            .quote{        width: 200px;       margin-left: 10px;       padding: 5px;       float: right;       border: 2px solid #000;       background-color:#F9ACAE;      }            .quote :last-child{        margin-bottom: 0;      }            #main{        column-count:2;        column-gap:20px;        column-rule: 1px solid #000;        -moz-column-count: 2;        -webkit-column-count: 2;        -moz-column-gap: 20px;        -webkit-column-gap: 20px;        -moz-column-rule: 1px solid #000;        -webkit-column-rule: 1px solid #000;      }       All the rules in the css code are pretty simple. The layout is achieved with that CSS rule #main{        column-count:2;        column-gap:20px;        column-rule: 1px solid #000;        -moz-column-count: 2;        -webkit-column-count: 2;        -moz-column-gap: 20px;        -webkit-column-gap: 20px;        -moz-column-rule: 1px solid #000;        -webkit-column-rule: 1px solid #000; Do note the column-count,column-gap and column-rule properties. These properties make the two column layout possible.Please have a look at the picture below to see why I used prefixes for Chrome (webkit) and Firefox(moz).It clearly indicates that the CSS 3 column layout are not supported from Firefox and Chrome.   Finally I test my simple HTML 5 page using the latest versions of Firefox,Internet Explorer and Chrome. In my machine I have installed Firefox 15.0.1.Have a look at the picture below to see how the page looks  I have installed Google Chrome 21.0 in my machine.Have a look at the picture below to see how the page looks Have a look at the picture below to see how my page looks in IE 10.  My page looks the same in all browsers. Hope it helps!!!

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  • CodePlex Daily Summary for Wednesday, March 02, 2011

    CodePlex Daily Summary for Wednesday, March 02, 2011Popular ReleasesDocument.Editor: 2011.9: Whats new for Document.Editor 2011.9: New Templates System New Plug-in System New Replace dialog New reset settings Minor Bug Fix's, improvements and speed upsTortoiseHg: TortoiseHg 2.0: TortoiseHg 2.0 is a complete rewrite of TortoiseHg 1.1, switching from PyGtk to PyQtVG Content Display Web Part: VG Content Display Web Part V1.0: Install package shall be installed using PowerShell or stsadm commands or using Central Administration interface. Please see instructions in the http://vgcdwp.codeplex.com/releases/view/61805#DownloadId=212622 file.DirectQ: Release 1.8.7 (Beta 3): Fixes some problems and adds some more enhancements.Sandcastle Help File Builder: SHFB v1.9.2.0 Release: This release supports the Sandcastle June 2010 Release (v2.6.10621.1). It includes full support for generating, installing, and removing MS Help Viewer files. This new release is compiled under .NET 4.0, supports Visual Studio 2010 solutions and projects as documentation sources, and adds support for projects targeting the Silverlight Framework. NOTE: The included help file and the online help have not been completely updated to reflect all changes in this release. A refresh will be issue...Network Monitor Open Source Parsers: Microsoft Network Monitor Parsers 3.4.2554: The Network Monitor Parsers packages contain parsers for more than 400 network protocols, including RFC based public protocols and protocols for Microsoft products defined in the Microsoft Open Specifications for Windows and SQL Server. NetworkMonitor_Parsers.msi is the base parser package which defines parsers for commonly used public protocols and protocols for Microsoft Windows. In this release, we have added 4 new protocol parsers and updated 79 existing parsers in the NetworkMonitor_Pa...Ajax Minifier: Microsoft Ajax Minifier 4.13: New features: switches and settings for turning off Conditional Compilation comment processing; for adding variable and/or function names that should not be renamed automatically; for adding manual renaming of variables/functions/properties; for automatic evaluation of certain literal expressions (but not all).Image Resizer for Windows: Image Resizer 3 Preview 1: Prepare to have your minds blown. This is the first preview of what will eventually become 39613. There are still a lot of rough edges and plenty of areas still under construction, but for your basic needs, it should be relativly stable. Note: You will need the .NET Framework 4 installed to use this version. Below is a status report of where this release is in terms of the overall goal for version 3. If you're feeling a bit technically ambitious and want to check out some of the features th...JSON Toolkit: JSON Toolkit 1.1: updated GetAllJsonObjects() method and GetAllProperties() methods to JsonObject and Properties propertiesFacebook Graph Toolkit: Facebook Graph Toolkit 1.0: Refer to http://computerbeacon.net for Documentation and Tutorial New features:added FQL support added Expires property to Api object added support for publishing to a user's friend / Facebook Page added support for posting and removing comments on posts added support for adding and removing likes on posts and comments added static methods for Page class added support for Iframe Application Tab of Facebook Page added support for obtaining the user's country, locale and age in If...ASP.NET MVC Project Awesome, jQuery Ajax helpers (controls): 1.7.1: A rich set of helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager small improvements for some helpers and AjaxDropdown has Data like the Lookup except it's value gets reset and list refilled if any element from data gets changedManaged Extensibility Framework: MEF 2 Preview 3: This release aims .net 4.0 and Silverlight 4.0. Accordingly, there are two solutions files. The assemblies are named System.ComponentModel.Composition.Codeplex.dll as a way to avoid clashing with the version shipped with the 4th version of the framework. Introduced CompositionOptions to container instantiation CompositionOptions.DisableSilentRejection makes MEF throw an exception on composition errors. Useful for diagnostics Support for open generics Support for attribute-less registr...PHPExcel: PHPExcel 1.7.6 Production: DonationsDonate via PayPal via PayPal. If you want to, we can also add your name / company on our Donation Acknowledgements page. PEAR channelWe now also have a full PEAR channel! Here's how to use it: New installation: pear channel-discover pear.pearplex.net pear install pearplex/PHPExcel Or if you've already installed PHPExcel before: pear upgrade pearplex/PHPExcel The official page can be found at http://pearplex.net. Want to contribute?Please refer the Contribute page.WPF Application Framework (WAF): WPF Application Framework (WAF) 2.0.0.4: Version: 2.0.0.4 (Milestone 4): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Remark The sample applications are using Microsoft’s IoC container MEF. However, the WPF Application Framework (WAF) doesn’t force you to use the same IoC container in your application. You can use ...VidCoder: 0.8.2: Updated auto-naming to handle seconds and frames ranges as well. Deprecated the {chapters} token for auto-naming in favor of {range}. Allowing file drag to preview window and enabling main window shortcut keys to work no matter what window is focused. Added option in config to enable giving custom names to audio tracks. (Note that these names will only show up certain players like iTunes or on the iPod. Players that support custom track names normally may not show them.) Added tooltips ...SQL Server Compact Toolbox: Standalone version 2.0 for SQL Server Compact 4.0: Download the Visual Studio add-in for SQL Server Compact 4.0 and 3.5 from here Standalone version of (most of) the same functionality as the add-in, for SQL Server Compact 4.0. Useful for anyone not having Visual Studio Professional or higher installed. Requires .NET 4.0. Any feedback much appreciated.Claims Based Identity & Access Control Guide: Drop 1 - Claims Identity Guide V2: Highlights of drop #1 This is the first drop of the new "Claims Identity Guide" edition. In this release you will find: All previous samples updated and enhanced. All code upgraded to .NET 4 and Visual Studio 2010. Extensive cleanup. Refactored Simulated Issuers: each solution now gets its own issuers. This results in much cleaner and simpler to understand code. Added Single Sign Out support. Added first sample using ACS ("ACS as a Federation Provider"). This sample extends the ori...Simple Notify: Simple Notify Beta 2011-02-25: Feature: host the service with a single click in console Feature: host the service as a windows service Feature: notification cient application Feature: push client application Feature: push notifications from your powershell script Feature: C# wrapper libraries for your applicationspatterns & practices: Project Silk: Project Silk Community Drop 3 - 25 Feb 2011: IntroductionWelcome to the third community drop of Project Silk. For this drop we are requesting feedback on overall application architecture, code review of the JavaScript Conductor and Widgets, and general direction of the application. Project Silk provides guidance and sample implementations that describe and illustrate recommended practices for building modern web applications using technologies such as HTML5, jQuery, CSS3 and Internet Explorer 9. This guidance is intended for experien...Minemapper: Minemapper v0.1.5: Now supports new Minecraft beta v1.3 map format, thanks to updated mcmap. Disabled biomes, until Minecraft Biome Extractor supports new format.New ProjectsAndrea Angella Personal Repository: This is my personal code repository.Audipyme: Aplicación web para el análisis y gestión de riesgos basado en la norma ISO 27001.Backfire 4 Umbraco: An implementation of backfire to work with UmbracoBadminton: Source codeCarManagement: Car ManagementCEQuery: CEQuery is usefull for managing SQL Server CE databases. It is developed in C# and supports SQL Server CE 3.5 and 4.0.Circuit Diagram: Circuit Diagram enables you to make electronic circuit diagrams and allows them to be exported as images. Ideal for use in coursework, you no longer have to use image editing programs to paste components together.CodeI2iportal: fdfdfCycling waypoints for Windows Phone 7: Show cycling POI on the Windows Phone 7d3d test: no summarydaemoniq - windows service hosting for mere mortals: Daemoniq provides a layer of a abstraction on top of System.ServiceProcess. This allows developers to concentrate on the functionality of their windows services in .Net by providing functionality such as configuration, deployment and debuggability.DimMock: DimMock is an object mocking framework for .NET Framework 4.0 that enables developers to mock simple and mildly complex classes extremely quick. euler 11: euler 11 problemeuler 30: euler 30euler 36 problem: euler 36 problemFiverw: Fiverw with ASP.NETGameList Creator for Wario's Jewel (GameBoy emulator for Windows Phone 7): Cette application vous permet de créer un catalogue de jeux vidéo pour des émulateurs mobiles et notamment Wario's Jewels, un emulateur GameBoy pour WP7. This application make it easier to create a game list for mobile emulators like Wario's Jewels, an WP7 GameBoy emulator.Gestion no Conformes: Gestión de No ConformesIamV Silverlight player: SilverLight photo album and music playerIcon Manager for Umbraco: Icon Manager for Umbraco - manage the icons within the setting secion of Umbraco by adding / removing from an available icon poolIE9 Extensions 4 Umbraco: A set of IE 9 extensions for Umbracoie9ify: A jQuery Plugin for adding IE9 features (site pinning, site mode, etc.) to your websitesImgUR.NET: ImgUr.NET helps the new .NET programmer host images on ImgUr. Developed in Visual Basic 2010, it can be used using only one line of code! You don't even need to parse the XML, ImgUr.NET automagically extract the URL and gives it to you! You can also get raw XML to parse yourself.Markup Programmability: Markup Programmability extends Blend Interactivity to a full programming language in markup: control flow, expressions, functions, objects, commands, converters, events, and more. Write an MVVM prototype in markup-only or use it for enhanced interactivity.MSCRM 4.0 Appointment Reminders (popup application without needing Outlook!): MSCRM 4.0 Appointment Reminders (popup application without Outlook!). Want to have your CRM Appointments popup on your desktop but don't have Outlook? Frustated by the CRM connection always going down and disconnecting itself? Built for local network use.myAspPracticals: my Asp.net pacticals-practical2NickMaoMix: It is only a sample project in Spring.Net + NHibernate + ASP.NET MVCOrchard Content Permissions: Orchard module enabling users to permit access to specified content items.Orchard LatestTwitter Module: Display latest Tweets for a user in an Orchard widget.PDF Little Signer: PDF Little Signer is a .NET3.5 library for self signing PDF document. It's very easy to use. It uses iTextSharp.perolas: perolasPGeom2D: PGeom2D is an attempt to derive the project http://livegeometry.codeplex.com/ as a more CAD oriented / desktop application. - it should use GDI+ instead of silverlight / WPF. - it should provide layers and blocks features. - it should support more export/import formats.Practical4: This is my practical4 webApplicationQxado: A .net framework written by BillQianReactive Extensions (Rx) Koans: Use this VS2010 project to learn Reactive (Rx) by doing small hacks in prepared lessons. Koans are a great way to get started learning Rx. Included Topics are: Observable Streams Time Events Aggregations Subscriptions RegularPractice: It is a project where i can upload my own prectice and demo projects of asp.net .RSVP04: RSVP systemschool project: Studiegids Projectshowyourfrustration: This web site is made for fun and enjoy over the internat.Silverlight Classified Cabinet: The Silverlight Classified Cabinet is a component that makes it easier to show classified items in a nice way. With the power of Silverlight, it lets users zoom and drag the items, categorize them into shelves and see detailed view. SkilledRESKAT: This Module helps SKilledRES for Automating Student Knowledge AssessmentTera X Emulator: Tera Emulator based on C#Test Tasks: Collection of completed test exercises.VG Content Display Web Part: VG Content Display Web Part is an alternative to Content Query Web Part (CQWP). It is easy to set up, uses custom XSLT file and it works with SharePoint 2010 Foundation. It allows displaying context-related content using current page metadata as filter values.vkPlayer: The standalone player for VKontakte siteWarMap Downloader: Easy way for download Warcraft 3 maps, from popular epicwar.com server. Hope you Enjoy!Web Crawler Sample: Simple solution that shows how NUnit, RhinoMock, Unity 2.0 DI container, and Parallel Extensions can play together. It is not considered as a best practice but rather aims to serve as a quick start solution.WP7Clipboard: WP7Clipboard is a library to mimic a shared clipboard on Windows Phone 7. This enables the user to copy objects from one application and post them into another without having to use a webservice/etc.????????? ?????????: "????????? ?????????" - ??? ???????, ??????????????? ????? ??????????????? ??????? ??? ??????? ??????? ????????????. ????????? ???????? ??? ?????? ? ????? ??????????? ??????? ??????? ?? ?????????? ????? ???.

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  • CodePlex Daily Summary for Monday, November 29, 2010

    CodePlex Daily Summary for Monday, November 29, 2010Popular Releasesexpression Blend 4.0 Comment Uncomment Xaml Code addin: Blend addin 1.0b: First releaseConfuser: Confuser v1.5: Change logs: +packer system +two confusion +console version *Enhanced encryption algorithm and protection. *Better documentationDotSpatial: DotSpatial 11-28-2001: This release introduces some exciting improvements. Support for big raster, both in display and changing the scheme. Faster raster scheme creation for all rasters. Caching of the "sample" values so once obtained the raster symbolizer dialog loads faster. Reprojection supported for raster and image classes. Affine transform fully supported for images and rasters, so skewed images are now possible. Projection uses better checks when loading unprojected layers. GDAL raster support f...SuperWebSocket: SuperWebSocket(60333): It is the first release of SuperWebSocket. Because it is base on SuperSocket, most features of SuperSocket are supported in SuperWebSocket.MDownloader: MDownloader-0.15.25.7002: Fixed updater Fixed FileServe Fixed LetItBitNotepad.NET: Notepad.NET 0.7 Preview 1: Whats New?* Optimized Code Generation: Which means it will run significantly faster. * Preview of Syntax Highlighting: Only VB.NET highlighting is supported, C# and Ruby will come in Preview 2. * Improved Editing Updates (when the line number, etc updates) to be more graceful. * Recent Documents works! * Images can be inserted but they're extremely large. Known Bugs* The Update Process hangs: This is a bug apparently spawning since 0.5. It will be fixed in Preview 2. Until then, perform a fr...Cropper: 1.9.4: Mostly fixes for issues with a few feature requests. Fixed Issues 2730 & 3638 & 14467 11044 11447 11448 11449 14665 Implemented Features 6123 11581PFC: PFC for PB 11.5: This is just a migration from the 11.0 code. No changes have been made yet (and they are needed) for it to work properly with 11.5.PDF Rider: PDF Rider 0.5: This release does not add any new feature for pdf manipulation, but enables automatic updates checking, so it is reccomended to install it in order to stay updated with next releases. Prerequisites * Microsoft Windows Operating Systems (XP - Vista - 7) * Microsoft .NET Framework 3.5 runtime * A PDF rendering software (i.e. Adobe Reader) that can be opened inside Internet Explorer. Installation instructionsChoose one of the following methods: 1. Download and run the "pdfRider0...Eneta community portal: Eneta Portal 0.1a: This is very first public deployment package of Eneta portal. This is test and development release and it is not suggested to use it on live or more complex development or test environments. You can find installation guides from documentation section of this site. For help and support please leave your message to discussions.XamlQuery/WPF - The Write Less, Do More, WPF Library: XamlQuery-WPF v1.2 (Runtime, Source): This is the first release of popular XamlQuery library for WPF. XamlQuery has already gained recognition among Silverlight developers.Math.NET Numerics: Beta 1: First beta of Math.NET Numerics. Only contains the managed linear algebra provider. Beta 2 will include the native linear algebra providers along with better documentation and examples.Minecraft GPS: Minecraft GPS 1.1: 1.1 Release New Features Compass! New style. Set opacity on main window to allow overlay of Minecraft.Code Sample from Microsoft: Visual Studio 2010 Code Samples 2010-11-25: Code samples for Visual Studio 2010Wii Backup Fusion: Wii Backup Fusion 0.8.5 Beta: - WBFS repair (default) options fixed - Transfer to image fixed - Settings ui widget names fixed - Some little bug fixes You need to reset the settings! Delete WiiBaFu's config file or registry entries on windows: Linux: ~/.config/WiiBaFu/wiibafu.conf Windows: HKEY_CURRENT_USER\Software\WiiBaFu\wiibafu Mac OS X: ~/Library/Preferences/com.wiibafu.wiibafu.plist Caution: This is a BETA version! Errors, crashes and data loss not impossible! Use in test environments only, not on productive syste...Minemapper: Minemapper v0.1.3: Added process count and world size calculation progress to the status bar. Added View->'Status Bar' menu item to show/hide the status bar. Status bar is automatically shown when loading a world. Added a prompt, when loading a world, to use or clear cached images.Sexy Select: sexy select v0.4: Changes in v0.4 Added method : elements. This returns all the option elements that are currently added to the select list Added method : selectOption. This method accepts two values, the element to be modified and the selected state. (true/false)Deep Zoom for WPF: First Release: This first release of the Deep Zoom control has the same source code, binaries and demos as the CodeProject article (http://www.codeproject.com/KB/WPF/DeepZoom.aspx).BlogEngine.NET: BlogEngine.NET 2.0 RC: This is a Release Candidate version for BlogEngine.NET 2.0. The most current, stable version of BlogEngine.NET is version 1.6. Find out more about the BlogEngine.NET 2.0 RC here. If you want to extend or modify BlogEngine.NET, you should download the source code. To get started, be sure to check out our installation documentation and the installation screencast. If you are upgrading from a previous version, please take a look at the Upgrading to BlogEngine.NET 2.0 instructions. As this ...NodeXL: Network Overview, Discovery and Exploration for Excel: NodeXL Excel Template, version 1.0.1.156: The NodeXL Excel template displays a network graph using edge and vertex lists stored in an Excel 2007 or Excel 2010 workbook. What's NewThis release adds a feature for aggregating the overall metrics in a folder full of NodeXL workbooks, adds geographical coordinates to the Twitter import features, and fixes a memory-related bug. See the Complete NodeXL Release History for details. Please Note: There is a new option in the setup program to install for "Just Me" or "Everyone." Most people...New ProjectsAntikCompta: AntikCompta is the easiest way to share comptability beetween an antiquaire and it's account manager.Blend Extensions: This shows you how to extend blend. It provides the basic plumbing for adding custom menu items, panes etc. codinghints: Sample codes of my blog codinghints.blogspot.comConvertitore dec->all: programma conversione da decimale a tutte le altre basi...DHCP Server: Open source managed ipv4 DHCP server implementation, written in C#. With extensive support for DHCP options it is ideally suited for configuring and netbooting local systems such as PLCs and blade racks. The permissive MIT license enables free commercial use and distribution.EducationProject: To be continuedEfficiency: Autumoon Efficiency.FarmerStore: Farmer store is e-commerical website about agricultural products.gStocksGadget: gStocksGadget is a Gadget for Windows Sidebar,display real-time stock prices(China's A-share market).Illumina PRT: Research ProjectImageCrawler: web crawler for downloading imagesInstantWatcher: Allows a user to view their Netflix Instant Watch Queue and launch a video.IRobotOnCLR - Control an "IRobot Create" Like You Are John Connor: This is a C# IRobot Create library w/ an accompanied Silverlight client that allows for remote interaction. To make use of this entire project, mounting a .net capable computer on the IRobot Create is suggested.it0758: it0758jkwcg: jkw cg form submit and managment, use xaf as testModificator of the URLs in the Web.config files: FilesModificatorAdmin utility 1. Purpose. 2. How it works. ================================================= 1. Purpose. In my current project we've got a lot of composite WCF-services. We have several environments: Development,Test1, Test2, Production. We don't have the service repository. That means when we move the services from one environment to another, we have to change addresses (URLs) in the <client> sections of all Web.config files (several dozens). Boring and error prone work, is...NARDAX: A collection of usefull API's and extensions that have been built out of necessity.OpenGLLesson: ?? ??? ???Peachlab ASP.NET Project Starter Kit: this is a personal project.picoCMS: picoCMS is an open-source content management system based on ASP.Net 3.5. It can be used as a learning platform for people who are totally new to ASP.Net and want to get things working around. SogouMusicBox Data: SogouMusicBox Data.Sound It Out - Phonetic Algorithms: Phonetic Algorithm helper Completed: NYSIIS In Progress: Soundex Metaphone Double Metaphone SPMetal Extender: SPMetal Extended helps SharePoint 2010 C# developers to remove some Linq to SharePoint 2010 limitations. You can extend the fields that Linq to SharePoint handles (including SharePoint Server 2010's): taxonaomy, publishing html, publishing image, attachments, created by, modifiedStrategyGame: A Fantasy Strategy Game.Task Scheduler Engine: Embed cron-like scheduling in your .NET application. Want your application to execute a task on the 12th second of the 29th minute of the 9th hour on Tuesdays? Piece of cake--2 lines of code. Coming in at ~250 lines of code, it offers considerable functionality with no bloat.The C# Todoist API: The C# Todoist API is a C# wrapper around the Todoist API documented at http://todoist.com/API/help. This is a work in progress.Tools Project: Tools to ease management.uObject: uObject is an Library That persist sample objectVisual Design: Visual Design is a collaborative diagramming editor written in silverlight to support design of software systems through diagramming, mainly UML, but even other types of diagram not supported in commercial and open source tools.Wusic - Web Music: Wusic.NET is an online video player and management system that highlights silverlight's rich-client functionality and potential. Some of the custom controls that make up Wusic.NET are drag n' drop, modality, sizability, YouTube and FaceBook integration, and Mac'ish menubar.XNADeviceEnumeration Component: A component which helps to enumerate a(all) graphics device/adapter on pc with XNA.XPlatformConvertCPP: Mesh Converter For XPlatformCPPZvP: First project to be tested. It's empty, so don't join us.?????「??」: ????????????????????。

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  • Abstracting functionality

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/22/abstracting-functionality.aspxWhat is more important than data? Functionality. Yes, I strongly believe we should switch to a functionality over data mindset in programming. Or actually switch back to it. Focus on functionality Functionality once was at the core of software development. Back when algorithms were the first thing you heard about in CS classes. Sure, data structures, too, were important - but always from the point of view of algorithms. (Niklaus Wirth gave one of his books the title “Algorithms + Data Structures” instead of “Data Structures + Algorithms” for a reason.) The reason for the focus on functionality? Firstly, because software was and is about doing stuff. Secondly because sufficient performance was hard to achieve, and only thirdly memory efficiency. But then hardware became more powerful. That gave rise to a new mindset: object orientation. And with it functionality was devalued. Data took over its place as the most important aspect. Now discussions revolved around structures motivated by data relationships. (John Beidler gave his book the title “Data Structures and Algorithms: An Object Oriented Approach” instead of the other way around for a reason.) Sure, this data could be embellished with functionality. But nevertheless functionality was second. When you look at (domain) object models what you mostly find is (domain) data object models. The common object oriented approach is: data aka structure over functionality. This is true even for the most modern modeling approaches like Domain Driven Design. Look at the literature and what you find is recommendations on how to get data structures right: aggregates, entities, value objects. I´m not saying this is what object orientation was invented for. But I´m saying that´s what I happen to see across many teams now some 25 years after object orientation became mainstream through C++, Delphi, and Java. But why should we switch back? Because software development cannot become truly agile with a data focus. The reason for that lies in what customers need first: functionality, behavior, operations. To be clear, that´s not why software is built. The purpose of software is to be more efficient than the alternative. Money mainly is spent to get a certain level of quality (e.g. performance, scalability, security etc.). But without functionality being present, there is nothing to work on the quality of. What customers want is functionality of a certain quality. ASAP. And tomorrow new functionality needs to be added, existing functionality needs to be changed, and quality needs to be increased. No customer ever wanted data or structures. Of course data should be processed. Data is there, data gets generated, transformed, stored. But how the data is structured for this to happen efficiently is of no concern to the customer. Ask a customer (or user) whether she likes the data structured this way or that way. She´ll say, “I don´t care.” But ask a customer (or user) whether he likes the functionality and its quality this way or that way. He´ll say, “I like it” (or “I don´t like it”). Build software incrementally From this very natural focus of customers and users on functionality and its quality follows we should develop software incrementally. That´s what Agility is about. Deliver small increments quickly and often to get frequent feedback. That way less waste is produced, and learning can take place much easier (on the side of the customer as well as on the side of developers). An increment is some added functionality or quality of functionality.[1] So as it turns out, Agility is about functionality over whatever. But software developers’ thinking is still stuck in the object oriented mindset of whatever over functionality. Bummer. I guess that (at least partly) explains why Agility always hits a glass ceiling in projects. It´s a clash of mindsets, of cultures. Driving software development by demanding small increases in functionality runs against thinking about software as growing (data) structures sprinkled with functionality. (Excuse me, if this sounds a bit broad-brush. But you get my point.) The need for abstraction In the end there need to be data structures. Of course. Small and large ones. The phrase functionality over data does not deny that. It´s not functionality instead of data or something. It´s just over, i.e. functionality should be thought of first. It´s a tad more important. It´s what the customer wants. That´s why we need a way to design functionality. Small and large. We need to be able to think about functionality before implementing it. We need to be able to reason about it among team members. We need to be able to communicate our mental models of functionality not just by speaking about them, but also on paper. Otherwise reasoning about it does not scale. We learned thinking about functionality in the small using flow charts, Nassi-Shneiderman diagrams, pseudo code, or UML sequence diagrams. That´s nice and well. But it does not scale. You can use these tools to describe manageable algorithms. But it does not work for the functionality triggered by pressing the “1-Click Order” on an amazon product page for example. There are several reasons for that, I´d say. Firstly, the level of abstraction over code is negligible. It´s essentially non-existent. Drawing a flow chart or writing pseudo code or writing actual code is very, very much alike. All these tools are about control flow like code is.[2] In addition all tools are computationally complete. They are about logic which is expressions and especially control statements. Whatever you code in Java you can fully (!) describe using a flow chart. And then there is no data. They are about control flow and leave out the data altogether. Thus data mostly is assumed to be global. That´s shooting yourself in the foot, as I hope you agree. Even if it´s functionality over data that does not mean “don´t think about data”. Right to the contrary! Functionality only makes sense with regard to data. So data needs to be in the picture right from the start - but it must not dominate the thinking. The above tools fail on this. Bottom line: So far we´re unable to reason in a scalable and abstract manner about functionality. That´s why programmers are so driven to start coding once they are presented with a problem. Programming languages are the only tool they´ve learned to use to reason about functional solutions. Or, well, there might be exceptions. Mathematical notation and SQL may have come to your mind already. Indeed they are tools on a higher level of abstraction than flow charts etc. That´s because they are declarative and not computationally complete. They leave out details - in order to deliver higher efficiency in devising overall solutions. We can easily reason about functionality using mathematics and SQL. That´s great. Except for that they are domain specific languages. They are not general purpose. (And they don´t scale either, I´d say.) Bummer. So to be more precise we need a scalable general purpose tool on a higher than code level of abstraction not neglecting data. Enter: Flow Design. Abstracting functionality using data flows I believe the solution to the problem of abstracting functionality lies in switching from control flow to data flow. Data flow very naturally is not about logic details anymore. There are no expressions and no control statements anymore. There are not even statements anymore. Data flow is declarative by nature. With data flow we get rid of all the limiting traits of former approaches to modeling functionality. In addition, nomen est omen, data flows include data in the functionality picture. With data flows, data is visibly flowing from processing step to processing step. Control is not flowing. Control is wherever it´s needed to process data coming in. That´s a crucial difference and needs some rewiring in your head to be fully appreciated.[2] Since data flows are declarative they are not the right tool to describe algorithms, though, I´d say. With them you don´t design functionality on a low level. During design data flow processing steps are black boxes. They get fleshed out during coding. Data flow design thus is more coarse grained than flow chart design. It starts on a higher level of abstraction - but then is not limited. By nesting data flows indefinitely you can design functionality of any size, without losing sight of your data. Data flows scale very well during design. They can be used on any level of granularity. And they can easily be depicted. Communicating designs using data flows is easy and scales well, too. The result of functional design using data flows is not algorithms (too low level), but processes. Think of data flows as descriptions of industrial production lines. Data as material runs through a number of processing steps to be analyzed, enhances, transformed. On the top level of a data flow design might be just one processing step, e.g. “execute 1-click order”. But below that are arbitrary levels of flows with smaller and smaller steps. That´s not layering as in “layered architecture”, though. Rather it´s a stratified design à la Abelson/Sussman. Refining data flows is not your grandpa´s functional decomposition. That was rooted in control flows. Refining data flows does not suffer from the limits of functional decomposition against which object orientation was supposed to be an antidote. Summary I´ve been working exclusively with data flows for functional design for the past 4 years. It has changed my life as a programmer. What once was difficult is now easy. And, no, I´m not using Clojure or F#. And I´m not a async/parallel execution buff. Designing the functionality of increments using data flows works great with teams. It produces design documentation which can easily be translated into code - in which then the smallest data flow processing steps have to be fleshed out - which is comparatively easy. Using a systematic translation approach code can mirror the data flow design. That way later on the design can easily be reproduced from the code if need be. And finally, data flow designs play well with object orientation. They are a great starting point for class design. But that´s a story for another day. To me data flow design simply is one of the missing links of systematic lightweight software design. There are also other artifacts software development can produce to get feedback, e.g. process descriptions, test cases. But customers can be delighted more easily with code based increments in functionality. ? No, I´m not talking about the endless possibilities this opens for parallel processing. Data flows are useful independently of multi-core processors and Actor-based designs. That´s my whole point here. Data flows are good for reasoning and evolvability. So forget about any special frameworks you might need to reap benefits from data flows. None are necessary. Translating data flow designs even into plain of Java is possible. ?

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  • Pain Comes Instantly

    - by user701213
    When I look back at recent blog entries – many of which are not all that current (more on where my available writing time is going later) – I am struck by how many of them focus on public policy or legislative issues instead of, say, the latest nefarious cyberattack or exploit (or everyone’s favorite new pastime: coining terms for the Coming Cyberpocalypse: “digital Pearl Harbor” is so 1941). Speaking of which, I personally hope evil hackers from Malefactoria will someday hack into my bathroom scale – which in a future time will be connected to the Internet because, gosh, wouldn’t it be great to have absolutely everything in your life Internet-enabled? – and recalibrate it so I’m 10 pounds thinner. The horror. In part, my focus on public policy is due to an admitted limitation of my skill set. I enjoy reading technical articles about exploits and cybersecurity trends, but writing a blog entry on those topics would take more research than I have time for and, quite honestly, doesn’t play to my strengths. The first rule of writing is “write what you know.” The bigger contributing factor to my recent paucity of blog entries is that more and more of my waking hours are spent engaging in “thrust and parry” activity involving emerging regulations of some sort or other. I’ve opined in earlier blogs about what constitutes good and reasonable public policy so nobody can accuse me of being reflexively anti-regulation. That said, you have so many cycles in the day, and most of us would rather spend it slaying actual dragons than participating in focus groups on whether dragons are really a problem, whether lassoing them (with organic, sustainable and recyclable lassos) is preferable to slaying them – after all, dragons are people, too - and whether we need lasso compliance auditors to make sure lassos are being used correctly and humanely. (A point that seems to evade many rule makers: slaying dragons actually accomplishes something, whereas talking about “approved dragon slaying procedures and requirements” wastes the time of those who are competent to dispatch actual dragons and who were doing so very well without the input of “dragon-slaying theorists.”) Unfortunately for so many of us who would just get on with doing our day jobs, cybersecurity is rapidly devolving into the “focus groups on dragon dispatching” realm, which actual dragons slayers have little choice but to participate in. The general trend in cybersecurity is that powers-that-be – which encompasses groups other than just legislators – are often increasingly concerned and therefore feel they need to Do Something About Cybersecurity. Many seem to believe that if only we had the right amount of regulation and oversight, there would be no data breaches: a breach simply must mean Someone Is At Fault and Needs Supervision. (Leaving aside the fact that we have lots of home invasions despite a) guard dogs b) liberal carry permits c) alarm systems d) etc.) Also note that many well-managed and security-aware organizations, like the US Department of Defense, still get hacked. More specifically, many powers-that-be feel they must direct industry in a multiplicity of ways, up to and including how we actually build and deploy information technology systems. The more prescriptive the requirement, the more regulators or overseers a) can be seen to be doing something b) feel as if they are doing something regardless of whether they are actually doing something useful or cost effective. Note: an unfortunate concomitant of Doing Something is that often the cure is worse than the ailment. That is, doing what overseers want creates unfortunate byproducts that they either didn’t foresee or worse, don’t care about. After all, the logic goes, we Did Something. Prescriptive practice in the IT industry is problematic for a number of reasons. For a start, prescriptive guidance is really only appropriate if: • It is cost effective• It is “current” (meaning, the guidance doesn’t require the use of the technical equivalent of buggy whips long after horse-drawn transportation has become passé)*• It is practical (that is, pragmatic, proven and effective in the real world, not theoretical and unproven)• It solves the right problem With the above in mind, heading up the list of “you must be joking” regulations are recent disturbing developments in the Payment Card Industry (PCI) world. I’d like to give PCI kahunas the benefit of the doubt about their intentions, except that efforts by Oracle among others to make them aware of “unfortunate side effects of your requirements” – which is as tactful I can be for reasons that I believe will become obvious below - have gone, to-date, unanswered and more importantly, unchanged. A little background on PCI before I get too wound up. In 2008, the Payment Card Industry (PCI) Security Standards Council (SSC) introduced the Payment Application Data Security Standard (PA-DSS). That standard requires vendors of payment applications to ensure that their products implement specific requirements and undergo security assessment procedures. In order to have an application listed as a Validated Payment Application (VPA) and available for use by merchants, software vendors are required to execute the PCI Payment Application Vendor Release Agreement (VRA). (Are you still with me through all the acronyms?) Beginning in August 2010, the VRA imposed new obligations on vendors that are extraordinary and extraordinarily bad, short-sighted and unworkable. Specifically, PCI requires vendors to disclose (dare we say “tell all?”) to PCI any known security vulnerabilities and associated security breaches involving VPAs. ASAP. Think about the impact of that. PCI is asking a vendor to disclose to them: • Specific details of security vulnerabilities • Including exploit information or technical details of the vulnerability • Whether or not there is any mitigation available (as in a patch) PCI, in turn, has the right to blab about any and all of the above – specifically, to distribute all the gory details of what is disclosed - to the PCI SSC, qualified security assessors (QSAs), and any affiliate or agent or adviser of those entities, who are in turn permitted to share it with their respective affiliates, agents, employees, contractors, merchants, processors, service providers and other business partners. This assorted crew can’t be more than, oh, hundreds of thousands of entities. Does anybody believe that several hundred thousand people can keep a secret? Or that several hundred thousand people are all equally trustworthy? Or that not one of the people getting all that information would blab vulnerability details to a bad guy, even by accident? Or be a bad guy who uses the information to break into systems? (Wait, was that the Easter Bunny that just hopped by? Bringing world peace, no doubt.) Sarcasm aside, common sense tells us that telling lots of people a secret is guaranteed to “unsecret” the secret. Notably, being provided details of a vulnerability (without a patch) is of little or no use to companies running the affected application. Few users have the technological sophistication to create a workaround, and even if they do, most workarounds break some other functionality in the application or surrounding environment. Also, given the differences among corporate implementations of any application, it is highly unlikely that a single workaround is going to work for all corporate users. So until a patch is developed by the vendor, users remain at risk of exploit: even more so if the details of vulnerability have been widely shared. Sharing that information widely before a patch is available therefore does not help users, and instead helps only those wanting to exploit known security bugs. There’s a shocker for you. Furthermore, we already know that insider information about security vulnerabilities inevitably leaks, which is why most vendors closely hold such information and limit dissemination until a patch is available (and frequently limit dissemination of technical details even with the release of a patch). That’s the industry norm, not that PCI seems to realize or acknowledge that. Why would anybody release a bunch of highly technical exploit information to a cast of thousands, whose only “vetting” is that they are members of a PCI consortium? Oracle has had personal experience with this problem, which is one reason why information on security vulnerabilities at Oracle is “need to know” (we use our own row level access control to limit access to security bugs in our bug database, and thus less than 1% of development has access to this information), and we don’t provide some customers with more information than others or with vulnerability information and/or patches earlier than others. Failure to remember “insider information always leaks” creates problems in the general case, and has created problems for us specifically. A number of years ago, one of the UK intelligence agencies had information about a non-public security vulnerability in an Oracle product that they circulated among other UK and Commonwealth defense and intelligence entities. Nobody, it should be pointed out, bothered to report the problem to Oracle, even though only Oracle could produce a patch. The vulnerability was finally reported to Oracle by (drum roll) a US-based commercial company, to whom the information had leaked. (Note: every time I tell this story, the MI-whatever agency that created the problem gets a bit shirty with us. I know they meant well and have improved their vulnerability handling/sharing processes but, dudes, next time you find an Oracle vulnerability, try reporting it to us first before blabbing to lots of people who can’t actually fix the problem. Thank you!) Getting back to PCI: clearly, these new disclosure obligations increase the risk of exploitation of a vulnerability in a VPA and thus, of misappropriation of payment card data and customer information that a VPA processes, stores or transmits. It stands to reason that VRA’s current requirement for the widespread distribution of security vulnerability exploit details -- at any time, but particularly before a vendor can issue a patch or a workaround -- is very poor public policy. It effectively publicizes information of great value to potential attackers while not providing compensating benefits - actually, any benefits - to payment card merchants or consumers. In fact, it magnifies the risk to payment card merchants and consumers. The risk is most prominent in the time before a patch has been released, since customers often have little option but to continue using an application or system despite the risks. However, the risk is not limited to the time before a patch is issued: customers often need days, or weeks, to apply patches to systems, based upon the complexity of the issue and dependence on surrounding programs. Rather than decreasing the available window of exploit, this requirement increases the available window of exploit, both as to time available to exploit a vulnerability and the ease with which it can be exploited. Also, why would hackers focus on finding new vulnerabilities to exploit if they can get “EZHack” handed to them in such a manner: a) a vulnerability b) in a payment application c) with exploit code: the “Hacking Trifecta!“ It’s fair to say that this is probably the exact opposite of what PCI – or any of us – would want. Established industry practice concerning vulnerability handling avoids the risks created by the VRA’s vulnerability disclosure requirements. Specifically, the norm is not to release information about a security bug until the associated patch (or a pretty darn good workaround) has been issued. Once a patch is available, the notice to the user community is a high-level communication discussing the product at issue, the level of risk associated with the vulnerability, and how to apply the patch. The notices do not include either the specific customers affected by the vulnerability or forensic reports with maps of the exploit (both of which are required by the current VRA). In this way, customers have the tools they need to prioritize patching and to help prevent an attack, and the information released does not increase the risk of exploit. Furthermore, many vendors already use industry standards for vulnerability description: Common Vulnerability Enumeration (CVE) and Common Vulnerability Scoring System (CVSS). CVE helps ensure that customers know which particular issues a patch addresses and CVSS helps customers determine how severe a vulnerability is on a relative scale. Industry already provides the tools customers need to know what the patch contains and how bad the problem is that the patch remediates. So, what’s a poor vendor to do? Oracle is reaching out to other vendors subject to PCI and attempting to enlist then in a broad effort to engage PCI in rethinking (that is, eradicating) these requirements. I would therefore urge all who care about this issue, but especially those in the vendor community whose applications are subject to PCI and who may not have know they were being asked to tell-all to PCI and put their customers at risk, to do one of the following: • Contact PCI with your concerns• Contact Oracle (we are looking for vendors to sign our statement of concern)• And make sure you tell your customers that you have to rat them out to PCI if there is a breach involving the payment application I like to be charitable and say “PCI meant well” but in as important a public policy issue as what you disclose about vulnerabilities, to whom and when, meaning well isn’t enough. We need to do well. PCI, as regards this particular issue, has not done well, and has compounded the error by thus far being nonresponsive to those of us who have labored mightily to try to explain why they might want to rethink telling the entire planet about security problems with no solutions. By Way of Explanation… Non-related to PCI whatsoever, and the explanation for why I have not been blogging a lot recently, I have been working on Other Writing Venues with my sister Diane (who has also worked in the tech sector, inflicting upgrades on unsuspecting and largely ungrateful end users). I am pleased to note that we have recently (self-)published the first in the Miss Information Technology Murder Mystery series, Outsourcing Murder. The genre might best be described as “chick lit meets geek scene.” Our sisterly nom de plume is Maddi Davidson and (shameless plug follows): you can order the paper version of the book on Amazon, or the Kindle or Nook versions on www.amazon.com or www.bn.com, respectively. From our book jacket: Emma Jones, a 20-something IT consultant, is working on an outsourcing project at Tahiti Tacos, a restaurant chain offering Polynexican cuisine: refried poi, anyone? Emma despises her boss Padmanabh, a brilliant but arrogant partner in GD Consulting. When Emma discovers His-Royal-Padness’s body (verdict: death by cricket bat), she becomes a suspect.With her overprotective family and her best friend Stacey providing endless support and advice, Emma stumbles her way through an investigation of Padmanabh’s murder, bolstered by fusion food feeding frenzies, endless cups of frou-frou coffee and serious surfing sessions. While Stacey knows a PI who owes her a favor, landlady Magda urges Emma to tart up her underwear drawer before the next cute cop with a search warrant arrives. Emma’s mother offers to fix her up with a PhD student at Berkeley and showers her with self-defense gizmos while her old lover Keoni beckons from Hawai’i. And everyone, even Shaun the barista, knows a good lawyer. Book 2, Denial of Service, is coming out this summer. * Given the rate of change in technology, today’s “thou shalts” are easily next year’s “buggy whip guidance.”

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • Change the default Icon on your jQuery UI Accordion

    - by hajan
    I've got this question in one of my previous blogs posted here (the same blog is posted on codeasp.net too), dealing with jQuery UI Accordion and I thought it's nice to recap this in a blog post so that I will have it documented for further reference. In the previous blog, I'm creating tabs content navigation using jQuery UI Accordion. So, it's quite simple code and all I do there is calling accordion() function. <script language="javascript" type="text/javascript">     $(function() {         $("#products").accordion();     }); </script> The default image icons for each item is the arrow. The accordion uses the right arrow and down arrow images. So, what we should do in order to change them? JQuery UI Accordion contains option with name icons that has header and headerSelected properties. We can override them with either the existing classes from jQuery UI themes or with our own. 1. Using existing jQuery UI Theme classes - Open the follownig link: http://jqueryui.com/themeroller/#icons You will see the icons available in the jQuery UI theme. Mouse over on each icon and you will see the class name for each icon. As you can see, each icon has class name constructed in the following way: ui-icon-<name> All icons in one image - In our example, I will use ui-icon-circle-plus  and ui-icon-circle-minus (plus and minus icons). - Lets set the icons <script language="javascript" type="text/javascript">     $(function() {         //initialize accordion                 $("#products").accordion();         //set accordion header options         $("#products").accordion("option", "icons",         { 'header': 'ui-icon-circle-plus', 'headerSelected': 'ui-icon-circle-minus' });     }); </script> From the code above, you can see that I first intialize the accordion plugin, and after I override the default icons with the ui-icon-circle-plyus for header and ui-icon-circle-minus for headerSelected. Here is the end result: So, now you see we have the plus/minus circle icons for the default header state and the selected header state.   2. Add my own icons - If you want to add your own icons, you can do that by creating your own custom css classes. - Lets create classes for both, the header default state and header selected state <style type="text/css">     .defaultIcon     {         background-image: url(images/icons/defaultIcon.png) !important;         width: 25px;         height: 25px;     }     .selectedIcon     {         background-image: url(images/icons/selectedIcon.png) !important;         width: 25px;         height: 25px;     } </style> As you can see, I use my own images placed in images/icons/ folder - default icon - selected icon One very important thing to note here is the !important key added on each background-image property. It's like that in order to give highest importancy to our image so that the default jQuery UI theme icon images will have less importancy and won't be used. And the jQuery code is: <script language="javascript" type="text/javascript">     $(function() {         //initialize accordion                 $("#products").accordion();         //set accordion header options         $("#products").accordion("option", "icons",         { 'header': 'defaultIcon', 'headerSelected': 'selectedIcon' });     }); </script> Note: For both #1 and #2 cases, we use the class names without adding . (dot) at the beginning of the name (as we do with selectors). That's because the the header and headerSelected properties accept classes only as a value, so the rest is done by the plugin itself. The complete code with my own custom images is: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server">     <title>jQuery Accordion</title>     <link type="text/css" href="http://ajax.microsoft.com/ajax/jquery.ui/1.8.5/themes/blitzer/jquery-ui.css"         rel="Stylesheet" />     <style type="text/css">         .defaultIcon         {             background-image: url(images/icons/defaultIcon.png) !important;             width: 25px;             height: 25px;         }         .selectedIcon         {             background-image: url(images/icons/selectedIcon.png) !important;             width: 25px;             height: 25px;         }     </style>     <script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.4.4.js"></script>     <script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jquery.ui/1.8.6/jquery-ui.js"></script>     <script language="javascript" type="text/javascript">         $(function() {             //initialize accordion                         $("#products").accordion();             //set accordion header options             $("#products").accordion("option", "icons",             { 'header': 'defaultIcon', 'headerSelected': 'selectedIcon' });         });             </script> </head> <body>     <form id="form1" runat="server">     <div id="products" style="width: 500px;">         <h3>             <a href="#">                 Product 1</a></h3>         <div>             <p>                 Lorem ipsum dolor sit amet, consectetur adipiscing elit. Phasellus in tortor metus,                 a aliquam dui. Mauris euismod lorem eget nulla semper semper. Vestibulum pretium                 rhoncus cursus. Vestibulum rhoncus, magna sit amet fermentum fringilla, nunc nisl                 pellentesque libero, nec commodo libero ipsum a tellus. Maecenas sed varius est.                 Sed vel risus at nisi imperdiet sollicitudin eget ac orci. Duis ac tristique sem.             </p>         </div>         <h3>             <a href="#">                 Product 2</a></h3>         <div>             <p>                 Aliquam pretium scelerisque nisl in malesuada. Proin dictum elementum rutrum. Etiam                 eleifend massa id dui porta tincidunt. Integer sodales nisi nec ligula lacinia tincidunt                 vel in purus. Mauris ultrices velit quis massa dignissim rhoncus. Proin posuere                 convallis euismod. Vestibulum convallis sagittis arcu id faucibus.             </p>         </div>         <h3>             <a href="#">                 Product 3</a></h3>         <div>             <p>                 Quisque quis magna id nibh laoreet condimentum a sed nisl. In hac habitasse platea                 dictumst. Proin sem eros, dignissim sed consequat sit amet, interdum id ante. Ut                 id nisi in ante fermentum accumsan vitae ut est. Morbi tellus enim, convallis ac                 rutrum a, condimentum ut turpis. Proin sit amet pretium felis.             </p>             <ul>                 <li>List item one</li>                 <li>List item two</li>                 <li>List item three</li>             </ul>         </div>     </div>     </form> </body> </html> The end result is: Hope this was helpful. Regards,Hajan

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  • Allowing connections initiated from outside

    - by Mark S. Rasmussen
    I've got an old Juniper SSG5 running ScreenOS 5.4.0r6.0. Once a day, more or less, it'll start randomly dropping packets at a rate of ~5-10%. We currently solve this issue by simply rebooting the unit, after which it resumes working in perfect condition. As this error has started appearing randomly, without any configuration or hardware changes, I'm assuming I've got an aging unit about to fail. As such, I've got a replacement SSG5 running ScreenOS 6.0. I've dumped the config on the 5.4 and imported it into a clean 6.0, and it seems to gladly accept it, and all my configuration seems to be A-OK. However, upon connecting the new unit, all outside-initiated connections seem to be blocked. If I browse our external IP from the inside, everything works perfectly, and it's not just port 80, SSH, Crashplan - all of our policies route correctly. All normal networking, initiated from the inside, work perfectly as well. If on the other hand I browse our external IP from the outside, everything is blocked. Barring differences between ScreenOS 5.4 and 6.0, the config is identical. Is there a setting somewhere that defines whether outside/inside initiated connections are allowed? unset key protection enable set clock timezone 1 set vrouter trust-vr sharable set vrouter "untrust-vr" exit set vrouter "trust-vr" unset auto-route-export exit set service "MyVOIP_UDP4569" protocol udp src-port 0-65535 dst-port 4569-4569 set service "MyVOIP_TCP22" protocol tcp src-port 0-65535 dst-port 22-22 set service "MyRDP" protocol tcp src-port 0-65535 dst-port 3389-3389 set service "MyRsync" protocol tcp src-port 0-65535 dst-port 873-873 set service "NZ_FTP" protocol tcp src-port 0-65535 dst-port 40000-41000 set service "NZ_FTP" + tcp src-port 0-65535 dst-port 21-21 set service "PPTP-VPN" protocol 47 src-port 2048-2048 dst-port 2048-2048 set service "PPTP-VPN" + tcp src-port 1024-65535 dst-port 1723-1723 set service "NZ_FMS_1935" protocol tcp src-port 0-65535 dst-port 1935-1935 set service "NZ_FMS_1935" + udp src-port 0-65535 dst-port 1935-1935 set service "NZ_FMS_8080" protocol tcp src-port 0-65535 dst-port 8080-8080 set service "CrashPlan Server" protocol tcp src-port 0-65535 dst-port 4280-4280 set service "CrashPlan Console" protocol tcp src-port 0-65535 dst-port 4282-4282 unset alg sip enable set alg appleichat enable unset alg appleichat re-assembly enable set alg sctp enable set auth-server "Local" id 0 set auth-server "Local" server-name "Local" set auth default auth server "Local" set auth radius accounting port 1646 set admin name "netscreen" set admin password "XXX" set admin auth web timeout 10 set admin auth dial-in timeout 3 set admin auth server "Local" set admin format dos set vip multi-port set zone "Trust" vrouter "trust-vr" set zone "Untrust" vrouter "trust-vr" set zone "DMZ" vrouter "trust-vr" set zone "VLAN" vrouter "trust-vr" set zone "Untrust-Tun" vrouter "trust-vr" set zone "Trust" tcp-rst set zone "Untrust" block unset zone "Untrust" tcp-rst set zone "MGT" block unset zone "V1-Trust" tcp-rst unset zone "V1-Untrust" tcp-rst set zone "DMZ" tcp-rst unset zone "V1-DMZ" tcp-rst unset zone "VLAN" tcp-rst set zone "Untrust" screen tear-drop set zone "Untrust" screen syn-flood set zone "Untrust" screen ping-death set zone "Untrust" screen ip-filter-src set zone "Untrust" screen land set zone "V1-Untrust" screen tear-drop set zone "V1-Untrust" screen syn-flood set zone "V1-Untrust" screen ping-death set zone "V1-Untrust" screen ip-filter-src set zone "V1-Untrust" screen land set interface ethernet0/0 phy full 100mb set interface ethernet0/3 phy full 100mb set interface ethernet0/4 phy full 100mb set interface ethernet0/5 phy full 100mb set interface ethernet0/6 phy full 100mb set interface "ethernet0/0" zone "Untrust" set interface "ethernet0/1" zone "Null" set interface "bgroup0" zone "Trust" set interface "bgroup1" zone "Trust" set interface "bgroup2" zone "Trust" set interface bgroup2 port ethernet0/2 set interface bgroup0 port ethernet0/3 set interface bgroup0 port ethernet0/4 set interface bgroup1 port ethernet0/5 set interface bgroup1 port ethernet0/6 unset interface vlan1 ip set interface ethernet0/0 ip 215.173.182.18/29 set interface ethernet0/0 route set interface bgroup0 ip 192.168.1.1/24 set interface bgroup0 nat set interface bgroup1 ip 192.168.2.1/24 set interface bgroup1 nat set interface bgroup2 ip 192.168.3.1/24 set interface bgroup2 nat set interface ethernet0/0 gateway 215.173.182.17 unset interface vlan1 bypass-others-ipsec unset interface vlan1 bypass-non-ip set interface ethernet0/0 ip manageable set interface bgroup0 ip manageable set interface bgroup1 ip manageable set interface bgroup2 ip manageable set interface bgroup0 manage mtrace unset interface bgroup1 manage ssh unset interface bgroup1 manage telnet unset interface bgroup1 manage snmp unset interface bgroup1 manage ssl unset interface bgroup1 manage web unset interface bgroup2 manage ssh unset interface bgroup2 manage telnet unset interface bgroup2 manage snmp unset interface bgroup2 manage ssl unset interface bgroup2 manage web set interface ethernet0/0 vip 215.173.182.19 2048 "PPTP-VPN" 192.168.1.131 set interface ethernet0/0 vip 215.173.182.19 + 4280 "CrashPlan Server" 192.168.1.131 set interface ethernet0/0 vip 215.173.182.19 + 4282 "CrashPlan Console" 192.168.1.131 set interface ethernet0/0 vip 215.173.182.22 22 "MyVOIP_TCP22" 192.168.2.127 set interface ethernet0/0 vip 215.173.182.22 + 4569 "MyVOIP_UDP4569" 192.168.2.127 set interface ethernet0/0 vip 215.173.182.22 + 3389 "MyRDP" 192.168.2.202 set interface ethernet0/0 vip 215.173.182.22 + 873 "MyRsync" 192.168.2.201 set interface ethernet0/0 vip 215.173.182.22 + 80 "HTTP" 192.168.2.202 set interface ethernet0/0 vip 215.173.182.22 + 2048 "PPTP-VPN" 192.168.2.201 set interface ethernet0/0 vip 215.173.182.22 + 8080 "NZ_FMS_8080" 192.168.2.216 set interface ethernet0/0 vip 215.173.182.22 + 1935 "NZ_FMS_1935" 192.168.2.216 set interface bgroup0 dhcp server service set interface bgroup1 dhcp server service set interface bgroup2 dhcp server service set interface bgroup0 dhcp server auto set interface bgroup1 dhcp server auto set interface bgroup2 dhcp server auto set interface bgroup0 dhcp server option domainname companyalan set interface bgroup0 dhcp server option dns1 192.168.1.131 set interface bgroup1 dhcp server option domainname companyblan set interface bgroup1 dhcp server option dns1 192.168.2.202 set interface bgroup2 dhcp server option dns1 8.8.8.8 set interface bgroup2 dhcp server option wins1 8.8.4.4 set interface bgroup0 dhcp server ip 192.168.1.2 to 192.168.1.116 set interface bgroup1 dhcp server ip 192.168.2.2 to 192.168.2.116 set interface bgroup2 dhcp server ip 192.168.3.2 to 192.168.3.126 unset interface bgroup0 dhcp server config next-server-ip unset interface bgroup1 dhcp server config next-server-ip unset interface bgroup2 dhcp server config next-server-ip set interface "ethernet0/0" mip 215.173.182.21 host 192.168.2.202 netmask 255.255.255.255 vr "trust-vr" set interface "serial0/0" modem settings "USR" init "AT&F" set interface "serial0/0" modem settings "USR" active set interface "serial0/0" modem speed 115200 set interface "serial0/0" modem retry 3 set interface "serial0/0" modem interval 10 set interface "serial0/0" modem idle-time 10 set flow tcp-mss unset flow tcp-syn-check unset flow tcp-syn-bit-check set flow reverse-route clear-text prefer set flow reverse-route tunnel always set pki authority default scep mode "auto" set pki x509 default cert-path partial set pki x509 dn name "[email protected]" set dns host dns1 0.0.0.0 set dns host dns2 0.0.0.0 set dns host dns3 0.0.0.0 set address "Trust" "192.168.1.0/24" 192.168.1.0 255.255.255.0 set address "Trust" "192.168.2.0/24" 192.168.2.0 255.255.255.0 set address "Trust" "192.168.3.0/24" 192.168.3.0 255.255.255.0 set crypto-policy exit set ike respond-bad-spi 1 set ike ikev2 ike-sa-soft-lifetime 60 unset ike ikeid-enumeration unset ike dos-protection unset ipsec access-session enable set ipsec access-session maximum 5000 set ipsec access-session upper-threshold 0 set ipsec access-session lower-threshold 0 set ipsec access-session dead-p2-sa-timeout 0 unset ipsec access-session log-error unset ipsec access-session info-exch-connected unset ipsec access-session use-error-log set vrouter "untrust-vr" exit set vrouter "trust-vr" exit set l2tp default ppp-auth chap set url protocol websense exit set policy id 1 from "Trust" to "Untrust" "Any" "Any" "ANY" permit set policy id 1 exit set policy id 2 from "Untrust" to "Trust" "Any" "VIP(215.173.182.19)" "PPTP-VPN" permit traffic set policy id 2 exit set policy id 3 from "Untrust" to "Trust" "Any" "VIP(215.173.182.22)" "HTTP" permit log set policy id 3 set service "MyRDP" set service "MyRsync" set service "MyVOIP_TCP22" set service "MyVOIP_UDP4569" exit set policy id 6 from "Trust" to "Trust" "192.168.1.0/24" "192.168.2.0/24" "ANY" deny set policy id 6 exit set policy id 7 from "Trust" to "Trust" "192.168.2.0/24" "192.168.1.0/24" "ANY" deny set policy id 7 exit set policy id 8 from "Trust" to "Trust" "192.168.3.0/24" "192.168.1.0/24" "ANY" deny set policy id 8 exit set policy id 9 from "Trust" to "Trust" "192.168.3.0/24" "192.168.2.0/24" "ANY" deny set policy id 9 exit set policy id 10 from "Untrust" to "Trust" "Any" "MIP(215.173.182.21)" "NZ_FTP" permit set policy id 10 exit set policy id 11 from "Untrust" to "Trust" "Any" "VIP(215.173.182.22)" "PPTP-VPN" permit set policy id 11 exit set policy id 12 from "Untrust" to "Trust" "Any" "VIP(215.173.182.22)" "NZ_FMS_1935" permit set policy id 12 set service "NZ_FMS_8080" exit set policy id 13 from "Untrust" to "Trust" "Any" "VIP(215.173.182.19)" "CrashPlan Console" permit set policy id 13 set service "CrashPlan Server" exit set nsmgmt bulkcli reboot-timeout 60 set ssh version v2 set config lock timeout 5 unset license-key auto-update set telnet client enable set snmp port listen 161 set snmp port trap 162 set vrouter "untrust-vr" exit set vrouter "trust-vr" unset add-default-route exit set vrouter "untrust-vr" exit set vrouter "trust-vr" exit Note that I've previously posted a similar question (pertaining to the same device & replacement, but ultimately caused by a malfunctioning switch, and thus clouding the current issue): Outbound traffic being blocked for MIP/VIPped servers (Juniper SSG5)

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  • Why should main() be short?

    - by Stargazer712
    I've been programming for over 9 years, and according to the advice of my first programming teacher, I always keep my main() function extremely short. At first I had no idea why. I just obeyed without understanding, much to the delight of my professors. After gaining experience, I realized that if I designed my code correctly, having a short main() function just sortof happened. Writing modularized code and following the single responsibility principle allowed my code to be designed in "bunches", and main() served as nothing more than a catalyst to get the program running. Fast forward to a few weeks ago, I was looking at Python's souce code, and I found the main() function: /* Minimal main program -- everything is loaded from the library */ ... int main(int argc, char **argv) { ... return Py_Main(argc, argv); } Yay Python. Short main() function == Good code. Programming teachers were right. Wanting to look deeper, I took a look at Py_Main. In its entirety, it is defined as follows: /* Main program */ int Py_Main(int argc, char **argv) { int c; int sts; char *command = NULL; char *filename = NULL; char *module = NULL; FILE *fp = stdin; char *p; int unbuffered = 0; int skipfirstline = 0; int stdin_is_interactive = 0; int help = 0; int version = 0; int saw_unbuffered_flag = 0; PyCompilerFlags cf; cf.cf_flags = 0; orig_argc = argc; /* For Py_GetArgcArgv() */ orig_argv = argv; #ifdef RISCOS Py_RISCOSWimpFlag = 0; #endif PySys_ResetWarnOptions(); while ((c = _PyOS_GetOpt(argc, argv, PROGRAM_OPTS)) != EOF) { if (c == 'c') { /* -c is the last option; following arguments that look like options are left for the command to interpret. */ command = (char *)malloc(strlen(_PyOS_optarg) + 2); if (command == NULL) Py_FatalError( "not enough memory to copy -c argument"); strcpy(command, _PyOS_optarg); strcat(command, "\n"); break; } if (c == 'm') { /* -m is the last option; following arguments that look like options are left for the module to interpret. */ module = (char *)malloc(strlen(_PyOS_optarg) + 2); if (module == NULL) Py_FatalError( "not enough memory to copy -m argument"); strcpy(module, _PyOS_optarg); break; } switch (c) { case 'b': Py_BytesWarningFlag++; break; case 'd': Py_DebugFlag++; break; case '3': Py_Py3kWarningFlag++; if (!Py_DivisionWarningFlag) Py_DivisionWarningFlag = 1; break; case 'Q': if (strcmp(_PyOS_optarg, "old") == 0) { Py_DivisionWarningFlag = 0; break; } if (strcmp(_PyOS_optarg, "warn") == 0) { Py_DivisionWarningFlag = 1; break; } if (strcmp(_PyOS_optarg, "warnall") == 0) { Py_DivisionWarningFlag = 2; break; } if (strcmp(_PyOS_optarg, "new") == 0) { /* This only affects __main__ */ cf.cf_flags |= CO_FUTURE_DIVISION; /* And this tells the eval loop to treat BINARY_DIVIDE as BINARY_TRUE_DIVIDE */ _Py_QnewFlag = 1; break; } fprintf(stderr, "-Q option should be `-Qold', " "`-Qwarn', `-Qwarnall', or `-Qnew' only\n"); return usage(2, argv[0]); /* NOTREACHED */ case 'i': Py_InspectFlag++; Py_InteractiveFlag++; break; /* case 'J': reserved for Jython */ case 'O': Py_OptimizeFlag++; break; case 'B': Py_DontWriteBytecodeFlag++; break; case 's': Py_NoUserSiteDirectory++; break; case 'S': Py_NoSiteFlag++; break; case 'E': Py_IgnoreEnvironmentFlag++; break; case 't': Py_TabcheckFlag++; break; case 'u': unbuffered++; saw_unbuffered_flag = 1; break; case 'v': Py_VerboseFlag++; break; #ifdef RISCOS case 'w': Py_RISCOSWimpFlag = 1; break; #endif case 'x': skipfirstline = 1; break; /* case 'X': reserved for implementation-specific arguments */ case 'U': Py_UnicodeFlag++; break; case 'h': case '?': help++; break; case 'V': version++; break; case 'W': PySys_AddWarnOption(_PyOS_optarg); break; /* This space reserved for other options */ default: return usage(2, argv[0]); /*NOTREACHED*/ } } if (help) return usage(0, argv[0]); if (version) { fprintf(stderr, "Python %s\n", PY_VERSION); return 0; } if (Py_Py3kWarningFlag && !Py_TabcheckFlag) /* -3 implies -t (but not -tt) */ Py_TabcheckFlag = 1; if (!Py_InspectFlag && (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0') Py_InspectFlag = 1; if (!saw_unbuffered_flag && (p = Py_GETENV("PYTHONUNBUFFERED")) && *p != '\0') unbuffered = 1; if (!Py_NoUserSiteDirectory && (p = Py_GETENV("PYTHONNOUSERSITE")) && *p != '\0') Py_NoUserSiteDirectory = 1; if ((p = Py_GETENV("PYTHONWARNINGS")) && *p != '\0') { char *buf, *warning; buf = (char *)malloc(strlen(p) + 1); if (buf == NULL) Py_FatalError( "not enough memory to copy PYTHONWARNINGS"); strcpy(buf, p); for (warning = strtok(buf, ","); warning != NULL; warning = strtok(NULL, ",")) PySys_AddWarnOption(warning); free(buf); } if (command == NULL && module == NULL && _PyOS_optind < argc && strcmp(argv[_PyOS_optind], "-") != 0) { #ifdef __VMS filename = decc$translate_vms(argv[_PyOS_optind]); if (filename == (char *)0 || filename == (char *)-1) filename = argv[_PyOS_optind]; #else filename = argv[_PyOS_optind]; #endif } stdin_is_interactive = Py_FdIsInteractive(stdin, (char *)0); if (unbuffered) { #if defined(MS_WINDOWS) || defined(__CYGWIN__) _setmode(fileno(stdin), O_BINARY); _setmode(fileno(stdout), O_BINARY); #endif #ifdef HAVE_SETVBUF setvbuf(stdin, (char *)NULL, _IONBF, BUFSIZ); setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ); setvbuf(stderr, (char *)NULL, _IONBF, BUFSIZ); #else /* !HAVE_SETVBUF */ setbuf(stdin, (char *)NULL); setbuf(stdout, (char *)NULL); setbuf(stderr, (char *)NULL); #endif /* !HAVE_SETVBUF */ } else if (Py_InteractiveFlag) { #ifdef MS_WINDOWS /* Doesn't have to have line-buffered -- use unbuffered */ /* Any set[v]buf(stdin, ...) screws up Tkinter :-( */ setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ); #else /* !MS_WINDOWS */ #ifdef HAVE_SETVBUF setvbuf(stdin, (char *)NULL, _IOLBF, BUFSIZ); setvbuf(stdout, (char *)NULL, _IOLBF, BUFSIZ); #endif /* HAVE_SETVBUF */ #endif /* !MS_WINDOWS */ /* Leave stderr alone - it should be unbuffered anyway. */ } #ifdef __VMS else { setvbuf (stdout, (char *)NULL, _IOLBF, BUFSIZ); } #endif /* __VMS */ #ifdef __APPLE__ /* On MacOS X, when the Python interpreter is embedded in an application bundle, it gets executed by a bootstrapping script that does os.execve() with an argv[0] that's different from the actual Python executable. This is needed to keep the Finder happy, or rather, to work around Apple's overly strict requirements of the process name. However, we still need a usable sys.executable, so the actual executable path is passed in an environment variable. See Lib/plat-mac/bundlebuiler.py for details about the bootstrap script. */ if ((p = Py_GETENV("PYTHONEXECUTABLE")) && *p != '\0') Py_SetProgramName(p); else Py_SetProgramName(argv[0]); #else Py_SetProgramName(argv[0]); #endif Py_Initialize(); if (Py_VerboseFlag || (command == NULL && filename == NULL && module == NULL && stdin_is_interactive)) { fprintf(stderr, "Python %s on %s\n", Py_GetVersion(), Py_GetPlatform()); if (!Py_NoSiteFlag) fprintf(stderr, "%s\n", COPYRIGHT); } if (command != NULL) { /* Backup _PyOS_optind and force sys.argv[0] = '-c' */ _PyOS_optind--; argv[_PyOS_optind] = "-c"; } if (module != NULL) { /* Backup _PyOS_optind and force sys.argv[0] = '-c' so that PySys_SetArgv correctly sets sys.path[0] to '' rather than looking for a file called "-m". See tracker issue #8202 for details. */ _PyOS_optind--; argv[_PyOS_optind] = "-c"; } PySys_SetArgv(argc-_PyOS_optind, argv+_PyOS_optind); if ((Py_InspectFlag || (command == NULL && filename == NULL && module == NULL)) && isatty(fileno(stdin))) { PyObject *v; v = PyImport_ImportModule("readline"); if (v == NULL) PyErr_Clear(); else Py_DECREF(v); } if (command) { sts = PyRun_SimpleStringFlags(command, &cf) != 0; free(command); } else if (module) { sts = RunModule(module, 1); free(module); } else { if (filename == NULL && stdin_is_interactive) { Py_InspectFlag = 0; /* do exit on SystemExit */ RunStartupFile(&cf); } /* XXX */ sts = -1; /* keep track of whether we've already run __main__ */ if (filename != NULL) { sts = RunMainFromImporter(filename); } if (sts==-1 && filename!=NULL) { if ((fp = fopen(filename, "r")) == NULL) { fprintf(stderr, "%s: can't open file '%s': [Errno %d] %s\n", argv[0], filename, errno, strerror(errno)); return 2; } else if (skipfirstline) { int ch; /* Push back first newline so line numbers remain the same */ while ((ch = getc(fp)) != EOF) { if (ch == '\n') { (void)ungetc(ch, fp); break; } } } { /* XXX: does this work on Win/Win64? (see posix_fstat) */ struct stat sb; if (fstat(fileno(fp), &sb) == 0 && S_ISDIR(sb.st_mode)) { fprintf(stderr, "%s: '%s' is a directory, cannot continue\n", argv[0], filename); fclose(fp); return 1; } } } if (sts==-1) { /* call pending calls like signal handlers (SIGINT) */ if (Py_MakePendingCalls() == -1) { PyErr_Print(); sts = 1; } else { sts = PyRun_AnyFileExFlags( fp, filename == NULL ? "<stdin>" : filename, filename != NULL, &cf) != 0; } } } /* Check this environment variable at the end, to give programs the * opportunity to set it from Python. */ if (!Py_InspectFlag && (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0') { Py_InspectFlag = 1; } if (Py_InspectFlag && stdin_is_interactive && (filename != NULL || command != NULL || module != NULL)) { Py_InspectFlag = 0; /* XXX */ sts = PyRun_AnyFileFlags(stdin, "<stdin>", &cf) != 0; } Py_Finalize(); #ifdef RISCOS if (Py_RISCOSWimpFlag) fprintf(stderr, "\x0cq\x0c"); /* make frontend quit */ #endif #ifdef __INSURE__ /* Insure++ is a memory analysis tool that aids in discovering * memory leaks and other memory problems. On Python exit, the * interned string dictionary is flagged as being in use at exit * (which it is). Under normal circumstances, this is fine because * the memory will be automatically reclaimed by the system. Under * memory debugging, it's a huge source of useless noise, so we * trade off slower shutdown for less distraction in the memory * reports. -baw */ _Py_ReleaseInternedStrings(); #endif /* __INSURE__ */ return sts; } Good God Almighty...it is big enough to sink the Titanic. It seems as though Python did the "Intro to Programming 101" trick and just moved all of main()'s code to a different function called it something very similar to "main". Here's my question: Is this code terribly written, or are there other reasons reasons to have a short main function? As it stands right now, I see absolutely no difference between doing this and just moving the code in Py_Main() back into main(). Am I wrong in thinking this?

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  • 64-bit Archives Needed

    - by user9154181
    A little over a year ago, we received a question from someone who was trying to build software on Solaris. He was getting errors from the ar command when creating an archive. At that time, the ar command on Solaris was a 32-bit command. There was more than 2GB of data, and the ar command was hitting the file size limit for a 32-bit process that doesn't use the largefile APIs. Even in 2011, 2GB is a very large amount of code, so we had not heard this one before. Most of our toolchain was extended to handle 64-bit sized data back in the 1990's, but archives were not changed, presumably because there was no perceived need for it. Since then of course, programs have continued to get larger, and in 2010, the time had finally come to investigate the issue and find a way to provide for larger archives. As part of that process, I had to do a deep dive into the archive format, and also do some Unix archeology. I'm going to record what I learned here, to document what Solaris does, and in the hope that it might help someone else trying to solve the same problem for their platform. Archive Format Details Archives are hardly cutting edge technology. They are still used of course, but their basic form hasn't changed in decades. Other than to fix a bug, which is rare, we don't tend to touch that code much. The archive file format is described in /usr/include/ar.h, and I won't repeat the details here. Instead, here is a rough overview of the archive file format, implemented by System V Release 4 (SVR4) Unix systems such as Solaris: Every archive starts with a "magic number". This is a sequence of 8 characters: "!<arch>\n". The magic number is followed by 1 or more members. A member starts with a fixed header, defined by the ar_hdr structure in/usr/include/ar.h. Immediately following the header comes the data for the member. Members must be padded at the end with newline characters so that they have even length. The requirement to pad members to an even length is a dead giveaway as to the age of the archive format. It tells you that this format dates from the 1970's, and more specifically from the era of 16-bit systems such as the PDP-11 that Unix was originally developed on. A 32-bit system would have required 4 bytes, and 64-bit systems such as we use today would probably have required 8 bytes. 2 byte alignment is a poor choice for ELF object archive members. 32-bit objects require 4 byte alignment, and 64-bit objects require 64-bit alignment. The link-editor uses mmap() to process archives, and if the members have the wrong alignment, we have to slide (copy) them to the correct alignment before we can access the ELF data structures inside. The archive format requires 2 byte padding, but it doesn't prohibit more. The Solaris ar command takes advantage of this, and pads ELF object members to 8 byte boundaries. Anything else is padded to 2 as required by the format. The archive header (ar_hdr) represents all numeric values using an ASCII text representation rather than as binary integers. This means that an archive that contains only text members can be viewed using tools such as cat, more, or a text editor. The original designers of this format clearly thought that archives would be used for many file types, and not just for objects. Things didn't turn out that way of course — nearly all archives contain relocatable objects for a single operating system and machine, and are used primarily as input to the link-editor (ld). Archives can have special members that are created by the ar command rather than being supplied by the user. These special members are all distinguished by having a name that starts with the slash (/) character. This is an unambiguous marker that says that the user could not have supplied it. The reason for this is that regular archive members are given the plain name of the file that was inserted to create them, and any path components are stripped off. Slash is the delimiter character used by Unix to separate path components, and as such cannot occur within a plain file name. The ar command hides the special members from you when you list the contents of an archive, so most users don't know that they exist. There are only two possible special members: A symbol table that maps ELF symbols to the object archive member that provides it, and a string table used to hold member names that exceed 15 characters. The '/' convention for tagging special members provides room for adding more such members should the need arise. As I will discuss below, we took advantage of this fact to add an alternate 64-bit symbol table special member which is used in archives that are larger than 4GB. When an archive contains ELF object members, the ar command builds a special archive member known as the symbol table that maps all ELF symbols in the object to the archive member that provides it. The link-editor uses this symbol table to determine which symbols are provided by the objects in that archive. If an archive has a symbol table, it will always be the first member in the archive, immediately following the magic number. Unlike member headers, symbol tables do use binary integers to represent offsets. These integers are always stored in big-endian format, even on a little endian host such as x86. The archive header (ar_hdr) provides 15 characters for representing the member name. If any member has a name that is longer than this, then the real name is written into a special archive member called the string table, and the member's name field instead contains a slash (/) character followed by a decimal representation of the offset of the real name within the string table. The string table is required to precede all normal archive members, so it will be the second member if the archive contains a symbol table, and the first member otherwise. The archive format is not designed to make finding a given member easy. Such operations move through the archive from front to back examining each member in turn, and run in O(n) time. This would be bad if archives were commonly used in that manner, but in general, they are not. Typically, the ar command is used to build an new archive from scratch, inserting all the objects in one operation, and then the link-editor accesses the members in the archive in constant time by using the offsets provided by the symbol table. Both of these operations are reasonably efficient. However, listing the contents of a large archive with the ar command can be rather slow. Factors That Limit Solaris Archive Size As is often the case, there was more than one limiting factor preventing Solaris archives from growing beyond the 32-bit limits of 2GB (32-bit signed) and 4GB (32-bit unsigned). These limits are listed in the order they are hit as archive size grows, so the earlier ones mask those that follow. The original Solaris archive file format can handle sizes up to 4GB without issue. However, the ar command was delivered as a 32-bit executable that did not use the largefile APIs. As such, the ar command itself could not create a file larger than 2GB. One can solve this by building ar with the largefile APIs which would allow it to reach 4GB, but a simpler and better answer is to deliver a 64-bit ar, which has the ability to scale well past 4GB. Symbol table offsets are stored as 32-bit big-endian binary integers, which limits the maximum archive size to 4GB. To get around this limit requires a different symbol table format, or an extension mechanism to the current one, similar in nature to the way member names longer than 15 characters are handled in member headers. The size field in the archive member header (ar_hdr) is an ASCII string capable of representing a 32-bit unsigned value. This places a 4GB size limit on the size of any individual member in an archive. In considering format extensions to get past these limits, it is important to remember that very few archives will require the ability to scale past 4GB for many years. The old format, while no beauty, continues to be sufficient for its purpose. This argues for a backward compatible fix that allows newer versions of Solaris to produce archives that are compatible with older versions of the system unless the size of the archive exceeds 4GB. Archive Format Differences Among Unix Variants While considering how to extend Solaris archives to scale to 64-bits, I wanted to know how similar archives from other Unix systems are to those produced by Solaris, and whether they had already solved the 64-bit issue. I've successfully moved archives between different Unix systems before with good luck, so I knew that there was some commonality. If it turned out that there was already a viable defacto standard for 64-bit archives, it would obviously be better to adopt that rather than invent something new. The archive file format is not formally standardized. However, the ar command and archive format were part of the original Unix from Bell Labs. Other systems started with that format, extending it in various often incompatible ways, but usually with the same common shared core. Most of these systems use the same magic number to identify their archives, despite the fact that their archives are not always fully compatible with each other. It is often true that archives can be copied between different Unix variants, and if the member names are short enough, the ar command from one system can often read archives produced on another. In practice, it is rare to find an archive containing anything other than objects for a single operating system and machine type. Such an archive is only of use on the type of system that created it, and is only used on that system. This is probably why cross platform compatibility of archives between Unix variants has never been an issue. Otherwise, the use of the same magic number in archives with incompatible formats would be a problem. I was able to find information for a number of Unix variants, described below. These can be divided roughly into three tribes, SVR4 Unix, BSD Unix, and IBM AIX. Solaris is a SVR4 Unix, and its archives are completely compatible with those from the other members of that group (GNU/Linux, HP-UX, and SGI IRIX). AIX AIX is an exception to rule that Unix archive formats are all based on the original Bell labs Unix format. It appears that AIX supports 2 formats (small and big), both of which differ in fundamental ways from other Unix systems: These formats use a different magic number than the standard one used by Solaris and other Unix variants. They include support for removing archive members from a file without reallocating the file, marking dead areas as unused, and reusing them when new archive items are inserted. They have a special table of contents member (File Member Header) which lets you find out everything that's in the archive without having to actually traverse the entire file. Their symbol table members are quite similar to those from other systems though. Their member headers are doubly linked, containing offsets to both the previous and next members. Of the Unix systems described here, AIX has the only format I saw that will have reasonable insert/delete performance for really large archives. Everyone else has O(n) performance, and are going to be slow to use with large archives. BSD BSD has gone through 4 versions of archive format, which are described in their manpage. They use the same member header as SVR4, but their symbol table format is different, and their scheme for long member names puts the name directly after the member header rather than into a string table. GNU/Linux The GNU toolchain uses the SVR4 format, and is compatible with Solaris. HP-UX HP-UX seems to follow the SVR4 model, and is compatible with Solaris. IRIX IRIX has 32 and 64-bit archives. The 32-bit format is the standard SVR4 format, and is compatible with Solaris. The 64-bit format is the same, except that the symbol table uses 64-bit integers. IRIX assumes that an archive contains objects of a single ELFCLASS/MACHINE, and any archive containing ELFCLASS64 objects receives a 64-bit symbol table. Although they only use it for 64-bit objects, nothing in the archive format limits it to ELFCLASS64. It would be perfectly valid to produce a 64-bit symbol table in an archive containing 32-bit objects, text files, or anything else. Tru64 Unix (Digital/Compaq/HP) Tru64 Unix uses a format much like ours, but their symbol table is a hash table, making specific symbol lookup much faster. The Solaris link-editor uses archives by examining the entire symbol table looking for unsatisfied symbols for the link, and not by looking up individual symbols, so there would be no benefit to Solaris from such a hash table. The Tru64 ld must use a different approach in which the hash table pays off for them. Widening the existing SVR4 archive symbol tables rather than inventing something new is the simplest path forward. There is ample precedent for this approach in the ELF world. When ELF was extended to support 64-bit objects, the approach was largely to take the existing data structures, and define 64-bit versions of them. We called the old set ELF32, and the new set ELF64. My guess is that there was no need to widen the archive format at that time, but had there been, it seems obvious that this is how it would have been done. The Implementation of 64-bit Solaris Archives As mentioned earlier, there was no desire to improve the fundamental nature of archives. They have always had O(n) insert/delete behavior, and for the most part it hasn't mattered. AIX made efforts to improve this, but those efforts did not find widespread adoption. For the purposes of link-editing, which is essentially the only thing that archives are used for, the existing format is adequate, and issues of backward compatibility trump the desire to do something technically better. Widening the existing symbol table format to 64-bits is therefore the obvious way to proceed. For Solaris 11, I implemented that, and I also updated the ar command so that a 64-bit version is run by default. This eliminates the 2 most significant limits to archive size, leaving only the limit on an individual archive member. We only generate a 64-bit symbol table if the archive exceeds 4GB, or when the new -S option to the ar command is used. This maximizes backward compatibility, as an archive produced by Solaris 11 is highly likely to be less than 4GB in size, and will therefore employ the same format understood by older versions of the system. The main reason for the existence of the -S option is to allow us to test the 64-bit format without having to construct huge archives to do so. I don't believe it will find much use outside of that. Other than the new ability to create and use extremely large archives, this change is largely invisible to the end user. When reading an archive, the ar command will transparently accept either form of symbol table. Similarly, the ELF library (libelf) has been updated to understand either format. Users of libelf (such as the link-editor ld) do not need to be modified to use the new format, because these changes are encapsulated behind the existing functions provided by libelf. As mentioned above, this work did not lift the limit on the maximum size of an individual archive member. That limit remains fixed at 4GB for now. This is not because we think objects will never get that large, for the history of computing says otherwise. Rather, this is based on an estimation that single relocatable objects of that size will not appear for a decade or two. A lot can change in that time, and it is better not to overengineer things by writing code that will sit and rot for years without being used. It is not too soon however to have a plan for that eventuality. When the time comes when this limit needs to be lifted, I believe that there is a simple solution that is consistent with the existing format. The archive member header size field is an ASCII string, like the name, and as such, the overflow scheme used for long names can also be used to handle the size. The size string would be placed into the archive string table, and its offset in the string table would then be written into the archive header size field using the same format "/ddd" used for overflowed names.

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  • Varnish default.vcl grace period

    - by Vladimir
    These are my settings for a grace period (/etc/varnish/default.vcl) sub vcl_recv { .... set req.grace = 360000s; ... } sub vcl_fetch { ... set beresp.grace = 360000s; ... } I tested Varnish using localhost and nodejs as a server. I started localhost, the site was up. Then I disconnected server and the site got disconnected in less than 2 min. It says: Error 503 Service Unavailable Service Unavailable Guru Meditation: XID: 1890127100 Varnish cache server Could you tell me what could be the problem? sub vcl_fetch { if (beresp.ttl < 120s) { ##std.log("Adjusting TTL"); set beresp.ttl = 36000s; ##120s; } # Do not cache the object if the backend application does not want us to. if (beresp.http.Cache-Control ~ "(no-cache|no-store|private|must-revalidate)") { return(hit_for_pass); } # Do not cache the object if the status is not in the 200s if (beresp.status >= 300) { # Remove the Set-Cookie header #remove beresp.http.Set-Cookie; return(hit_for_pass); } # # Everything below here should be cached # # Remove the Set-Cookie header ####remove beresp.http.Set-Cookie; # Set the grace time ## set beresp.grace = 1s; //change this to minutes in case of app shutdown set beresp.grace = 360000s; ## 10 hour - reduce if it has negative impact # Static assets - browser caches tpiphem for a long time. if (req.url ~ "\.(css|js|.js|jpg|jpeg|gif|ico|png)\??\d*$") { /* Remove Expires from backend, it's not long enough */ unset beresp.http.expires; /* Set the clients TTL on this object */ set beresp.http.cache-control = "public, max-age=31536000"; /* marker for vcl_deliver to reset Age: */ set beresp.http.magicmarker = "1"; } else { set beresp.http.Cache-Control = "private, max-age=0, must-revalidate"; set beresp.http.Pragma = "no-cache"; } if (req.url ~ "\.(css|js|min|)\??\d*$") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } ##do not duplicate these settings if (req.url ~ ".css") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } if (req.url ~ ".js") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } if (req.url ~ ".min") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } ## If the request to the backend returns a code other than 200, restart the loop ## If the number of restarts reaches the value of the parameter max_restarts, ## the request will be error'ed. max_restarts defaults to 4. This prevents ## an eternal loop in the event that, e.g., the object does not exist at all. if (beresp.status != 200 && beresp.status != 403 && beresp.status != 404) { return(restart); } if (beresp.status == 302) { return(deliver); } # Never cache posts if (req.url ~ "\/post\/" || req.url ~ "\/submit\/" || req.url ~ "\/ask\/" || req.url ~ "\/add\/") { return(hit_for_pass); } ##check this setting to ensure that it does not cause issues for browsers with no gzip if (beresp.http.content-type ~ "text") { set beresp.do_gzip = true; } if (beresp.http.Set-Cookie) { return(deliver); } ##if (req.url == "/index.html") { set beresp.do_esi = true; ##} ## check if this is needed or should be used # return(deliver); the object return(deliver); } sub vcl_recv { ##avoid leeching of images call hot_link; set req.grace = 360000s; ##2m ## if one backend is down - use another if (req.restarts == 0) { set req.backend = cache_director; ##we can specify individual VMs } else if (req.restarts == 1) { set req.backend = cache_director; } ## post calls should not be cached - add cookie for these requests if using micro-caching # Pass requests that are not GET or HEAD if (req.request != "GET" && req.request != "HEAD") { return(pass); ## return(pass) goes to backend - not cache } # Don't cache the result of a redirect if (req.http.Referer ~ "redir" || req.http.Origin ~ "jumpto") { return(pass); } # Don't cache the result of a redirect (asking for logon) if (req.http.Referer ~ "post" || req.http.Referer ~ "submit" || req.http.Referer ~ "add" || req.http.Referer ~ "ask") { return(pass); } # Never cache posts - ensure that we do not use these strings in our URLs' that need to be cached if (req.url ~ "\/post\/" || req.url ~ "\/submit\/" || req.url ~ "\/ask\/" || req.url ~ "\/add\/") { return(pass); } ## if (req.http.Authorization || req.http.Cookie) { if (req.http.Authorization) { /* Not cacheable by default */ return (pass); } # Handle compression correctly. Different browsers send different # "Accept-Encoding" headers, even though they mostly all support the same # compression mechanisms. By consolidating these compression headers into # a consistent format, we can reduce the size of the cache and get more hits. # @see: http:// varnish.projects.linpro.no/wiki/FAQ/Compression if (req.http.Accept-Encoding) { if (req.url ~ "\.(jpg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|ico)$") { # No point in compressing these remove req.http.Accept-Encoding; } else if (req.http.Accept-Encoding ~ "gzip") { # If the browser supports it, we'll use gzip. set req.http.Accept-Encoding = "gzip"; } else if (req.http.Accept-Encoding ~ "deflate") { # Next, try deflate if it is supported. set req.http.Accept-Encoding = "deflate"; } else { # Unknown algorithm. Remove it and send unencoded. unset req.http.Accept-Encoding; } } # lookup graphics, css, js & ico files in the cache if (req.url ~ "\.(png|gif|jpg|jpeg|css|.js|ico)$") { return(lookup); } ##added on 0918 - check if it causes issues with user specific content if (req.request == "GET" && req.http.cookie) { return(lookup); } # Pipe requests that are non-RFC2616 or CONNECT which is weird. if (req.request != "GET" && req.request != "HEAD" && req.request != "PUT" && req.request != "POST" && req.request != "TRACE" && req.request != "OPTIONS" && req.request != "DELETE") { ##closing connection and calling pipe return(pipe); } ##purge content via localhost only if (req.request == "PURGE") { if (!client.ip ~ purge) { error 405 "Not allowed."; } return(lookup); } ## do we need this? ## return(lookup); }

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  • C#/.NET Little Wonders: The Useful But Overlooked Sets

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  Today we will be looking at two set implementations in the System.Collections.Generic namespace: HashSet<T> and SortedSet<T>.  Even though most people think of sets as mathematical constructs, they are actually very useful classes that can be used to help make your application more performant if used appropriately. A Background From Math In mathematical terms, a set is an unordered collection of unique items.  In other words, the set {2,3,5} is identical to the set {3,5,2}.  In addition, the set {2, 2, 4, 1} would be invalid because it would have a duplicate item (2).  In addition, you can perform set arithmetic on sets such as: Intersections: The intersection of two sets is the collection of elements common to both.  Example: The intersection of {1,2,5} and {2,4,9} is the set {2}. Unions: The union of two sets is the collection of unique items present in either or both set.  Example: The union of {1,2,5} and {2,4,9} is {1,2,4,5,9}. Differences: The difference of two sets is the removal of all items from the first set that are common between the sets.  Example: The difference of {1,2,5} and {2,4,9} is {1,5}. Supersets: One set is a superset of a second set if it contains all elements that are in the second set. Example: The set {1,2,5} is a superset of {1,5}. Subsets: One set is a subset of a second set if all the elements of that set are contained in the first set. Example: The set {1,5} is a subset of {1,2,5}. If We’re Not Doing Math, Why Do We Care? Now, you may be thinking: why bother with the set classes in C# if you have no need for mathematical set manipulation?  The answer is simple: they are extremely efficient ways to determine ownership in a collection. For example, let’s say you are designing an order system that tracks the price of a particular equity, and once it reaches a certain point will trigger an order.  Now, since there’s tens of thousands of equities on the markets, you don’t want to track market data for every ticker as that would be a waste of time and processing power for symbols you don’t have orders for.  Thus, we just want to subscribe to the stock symbol for an equity order only if it is a symbol we are not already subscribed to. Every time a new order comes in, we will check the list of subscriptions to see if the new order’s stock symbol is in that list.  If it is, great, we already have that market data feed!  If not, then and only then should we subscribe to the feed for that symbol. So far so good, we have a collection of symbols and we want to see if a symbol is present in that collection and if not, add it.  This really is the essence of set processing, but for the sake of comparison, let’s say you do a list instead: 1: // class that handles are order processing service 2: public sealed class OrderProcessor 3: { 4: // contains list of all symbols we are currently subscribed to 5: private readonly List<string> _subscriptions = new List<string>(); 6:  7: ... 8: } Now whenever you are adding a new order, it would look something like: 1: public PlaceOrderResponse PlaceOrder(Order newOrder) 2: { 3: // do some validation, of course... 4:  5: // check to see if already subscribed, if not add a subscription 6: if (!_subscriptions.Contains(newOrder.Symbol)) 7: { 8: // add the symbol to the list 9: _subscriptions.Add(newOrder.Symbol); 10: 11: // do whatever magic is needed to start a subscription for the symbol 12: } 13:  14: // place the order logic! 15: } What’s wrong with this?  In short: performance!  Finding an item inside a List<T> is a linear - O(n) – operation, which is not a very performant way to find if an item exists in a collection. (I used to teach algorithms and data structures in my spare time at a local university, and when you began talking about big-O notation you could immediately begin to see eyes glossing over as if it was pure, useless theory that would not apply in the real world, but I did and still do believe it is something worth understanding well to make the best choices in computer science). Let’s think about this: a linear operation means that as the number of items increases, the time that it takes to perform the operation tends to increase in a linear fashion.  Put crudely, this means if you double the collection size, you might expect the operation to take something like the order of twice as long.  Linear operations tend to be bad for performance because they mean that to perform some operation on a collection, you must potentially “visit” every item in the collection.  Consider finding an item in a List<T>: if you want to see if the list has an item, you must potentially check every item in the list before you find it or determine it’s not found. Now, we could of course sort our list and then perform a binary search on it, but sorting is typically a linear-logarithmic complexity – O(n * log n) - and could involve temporary storage.  So performing a sort after each add would probably add more time.  As an alternative, we could use a SortedList<TKey, TValue> which sorts the list on every Add(), but this has a similar level of complexity to move the items and also requires a key and value, and in our case the key is the value. This is why sets tend to be the best choice for this type of processing: they don’t rely on separate keys and values for ordering – so they save space – and they typically don’t care about ordering – so they tend to be extremely performant.  The .NET BCL (Base Class Library) has had the HashSet<T> since .NET 3.5, but at that time it did not implement the ISet<T> interface.  As of .NET 4.0, HashSet<T> implements ISet<T> and a new set, the SortedSet<T> was added that gives you a set with ordering. HashSet<T> – For Unordered Storage of Sets When used right, HashSet<T> is a beautiful collection, you can think of it as a simplified Dictionary<T,T>.  That is, a Dictionary where the TKey and TValue refer to the same object.  This is really an oversimplification, but logically it makes sense.  I’ve actually seen people code a Dictionary<T,T> where they store the same thing in the key and the value, and that’s just inefficient because of the extra storage to hold both the key and the value. As it’s name implies, the HashSet<T> uses a hashing algorithm to find the items in the set, which means it does take up some additional space, but it has lightning fast lookups!  Compare the times below between HashSet<T> and List<T>: Operation HashSet<T> List<T> Add() O(1) O(1) at end O(n) in middle Remove() O(1) O(n) Contains() O(1) O(n)   Now, these times are amortized and represent the typical case.  In the very worst case, the operations could be linear if they involve a resizing of the collection – but this is true for both the List and HashSet so that’s a less of an issue when comparing the two. The key thing to note is that in the general case, HashSet is constant time for adds, removes, and contains!  This means that no matter how large the collection is, it takes roughly the exact same amount of time to find an item or determine if it’s not in the collection.  Compare this to the List where almost any add or remove must rearrange potentially all the elements!  And to find an item in the list (if unsorted) you must search every item in the List. So as you can see, if you want to create an unordered collection and have very fast lookup and manipulation, the HashSet is a great collection. And since HashSet<T> implements ICollection<T> and IEnumerable<T>, it supports nearly all the same basic operations as the List<T> and can use the System.Linq extension methods as well. All we have to do to switch from a List<T> to a HashSet<T>  is change our declaration.  Since List and HashSet support many of the same members, chances are we won’t need to change much else. 1: public sealed class OrderProcessor 2: { 3: private readonly HashSet<string> _subscriptions = new HashSet<string>(); 4:  5: // ... 6:  7: public PlaceOrderResponse PlaceOrder(Order newOrder) 8: { 9: // do some validation, of course... 10: 11: // check to see if already subscribed, if not add a subscription 12: if (!_subscriptions.Contains(newOrder.Symbol)) 13: { 14: // add the symbol to the list 15: _subscriptions.Add(newOrder.Symbol); 16: 17: // do whatever magic is needed to start a subscription for the symbol 18: } 19: 20: // place the order logic! 21: } 22:  23: // ... 24: } 25: Notice, we didn’t change any code other than the declaration for _subscriptions to be a HashSet<T>.  Thus, we can pick up the performance improvements in this case with minimal code changes. SortedSet<T> – Ordered Storage of Sets Just like HashSet<T> is logically similar to Dictionary<T,T>, the SortedSet<T> is logically similar to the SortedDictionary<T,T>. The SortedSet can be used when you want to do set operations on a collection, but you want to maintain that collection in sorted order.  Now, this is not necessarily mathematically relevant, but if your collection needs do include order, this is the set to use. So the SortedSet seems to be implemented as a binary tree (possibly a red-black tree) internally.  Since binary trees are dynamic structures and non-contiguous (unlike List and SortedList) this means that inserts and deletes do not involve rearranging elements, or changing the linking of the nodes.  There is some overhead in keeping the nodes in order, but it is much smaller than a contiguous storage collection like a List<T>.  Let’s compare the three: Operation HashSet<T> SortedSet<T> List<T> Add() O(1) O(log n) O(1) at end O(n) in middle Remove() O(1) O(log n) O(n) Contains() O(1) O(log n) O(n)   The MSDN documentation seems to indicate that operations on SortedSet are O(1), but this seems to be inconsistent with its implementation and seems to be a documentation error.  There’s actually a separate MSDN document (here) on SortedSet that indicates that it is, in fact, logarithmic in complexity.  Let’s put it in layman’s terms: logarithmic means you can double the collection size and typically you only add a single extra “visit” to an item in the collection.  Take that in contrast to List<T>’s linear operation where if you double the size of the collection you double the “visits” to items in the collection.  This is very good performance!  It’s still not as performant as HashSet<T> where it always just visits one item (amortized), but for the addition of sorting this is a good thing. Consider the following table, now this is just illustrative data of the relative complexities, but it’s enough to get the point: Collection Size O(1) Visits O(log n) Visits O(n) Visits 1 1 1 1 10 1 4 10 100 1 7 100 1000 1 10 1000   Notice that the logarithmic – O(log n) – visit count goes up very slowly compare to the linear – O(n) – visit count.  This is because since the list is sorted, it can do one check in the middle of the list, determine which half of the collection the data is in, and discard the other half (binary search).  So, if you need your set to be sorted, you can use the SortedSet<T> just like the HashSet<T> and gain sorting for a small performance hit, but it’s still faster than a List<T>. Unique Set Operations Now, if you do want to perform more set-like operations, both implementations of ISet<T> support the following, which play back towards the mathematical set operations described before: IntersectWith() – Performs the set intersection of two sets.  Modifies the current set so that it only contains elements also in the second set. UnionWith() – Performs a set union of two sets.  Modifies the current set so it contains all elements present both in the current set and the second set. ExceptWith() – Performs a set difference of two sets.  Modifies the current set so that it removes all elements present in the second set. IsSupersetOf() – Checks if the current set is a superset of the second set. IsSubsetOf() – Checks if the current set is a subset of the second set. For more information on the set operations themselves, see the MSDN description of ISet<T> (here). What Sets Don’t Do Don’t get me wrong, sets are not silver bullets.  You don’t really want to use a set when you want separate key to value lookups, that’s what the IDictionary implementations are best for. Also sets don’t store temporal add-order.  That is, if you are adding items to the end of a list all the time, your list is ordered in terms of when items were added to it.  This is something the sets don’t do naturally (though you could use a SortedSet with an IComparer with a DateTime but that’s overkill) but List<T> can. Also, List<T> allows indexing which is a blazingly fast way to iterate through items in the collection.  Iterating over all the items in a List<T> is generally much, much faster than iterating over a set. Summary Sets are an excellent tool for maintaining a lookup table where the item is both the key and the value.  In addition, if you have need for the mathematical set operations, the C# sets support those as well.  The HashSet<T> is the set of choice if you want the fastest possible lookups but don’t care about order.  In contrast the SortedSet<T> will give you a sorted collection at a slight reduction in performance.   Technorati Tags: C#,.Net,Little Wonders,BlackRabbitCoder,ISet,HashSet,SortedSet

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  • Microsoft Introduces WebMatrix

    - by Rick Strahl
    originally published in CoDe Magazine Editorial Microsoft recently released the first CTP of a new development environment called WebMatrix, which along with some of its supporting technologies are squarely aimed at making the Microsoft Web Platform more approachable for first-time developers and hobbyists. But in the process, it also provides some updated technologies that can make life easier for existing .NET developers. Let’s face it: ASP.NET development isn’t exactly trivial unless you already have a fair bit of familiarity with sophisticated development practices. Stick a non-developer in front of Visual Studio .NET or even the Visual Web Developer Express edition and it’s not likely that the person in front of the screen will be very productive or feel inspired. Yet other technologies like PHP and even classic ASP did provide the ability for non-developers and hobbyists to become reasonably proficient in creating basic web content quickly and efficiently. WebMatrix appears to be Microsoft’s attempt to bring back some of that simplicity with a number of technologies and tools. The key is to provide a friendly and fully self-contained development environment that provides all the tools needed to build an application in one place, as well as tools that allow publishing of content and databases easily to the web server. WebMatrix is made up of several components and technologies: IIS Developer Express IIS Developer Express is a new, self-contained development web server that is fully compatible with IIS 7.5 and based on the same codebase that IIS 7.5 uses. This new development server replaces the much less compatible Cassini web server that’s been used in Visual Studio and the Express editions. IIS Express addresses a few shortcomings of the Cassini server such as the inability to serve custom ISAPI extensions (i.e., things like PHP or ASP classic for example), as well as not supporting advanced authentication. IIS Developer Express provides most of the IIS 7.5 feature set providing much better compatibility between development and live deployment scenarios. SQL Server Compact 4.0 Database access is a key component for most web-driven applications, but on the Microsoft stack this has mostly meant you have to use SQL Server or SQL Server Express. SQL Server Compact is not new-it’s been around for a few years, but it’s been severely hobbled in the past by terrible tool support and the inability to support more than a single connection in Microsoft’s attempt to avoid losing SQL Server licensing. The new release of SQL Server Compact 4.0 supports multiple connections and you can run it in ASP.NET web applications simply by installing an assembly into the bin folder of the web application. In effect, you don’t have to install a special system configuration to run SQL Compact as it is a drop-in database engine: Copy the small assembly into your BIN folder (or from the GAC if installed fully), create a connection string against a local file-based database file, and then start firing SQL requests. Additionally WebMatrix includes nice tools to edit the database tables and files, along with tools to easily upsize (and hopefully downsize in the future) to full SQL Server. This is a big win, pending compatibility and performance limits. In my simple testing the data engine performed well enough for small data sets. This is not only useful for web applications, but also for desktop applications for which a fully installed SQL engine like SQL Server would be overkill. Having a local data store in those applications that can potentially be accessed by multiple users is a welcome feature. ASP.NET Razor View Engine What? Yet another native ASP.NET view engine? We already have Web Forms and various different flavors of using that view engine with Web Forms and MVC. Do we really need another? Microsoft thinks so, and Razor is an implementation of a lightweight, script-only view engine. Unlike the Web Forms view engine, Razor works only with inline code, snippets, and markup; therefore, it is more in line with current thinking of what a view engine should represent. There’s no support for a “page model” or any of the other Web Forms features of the full-page framework, but just a lightweight scripting engine that works with plain markup plus embedded expressions and code. The markup syntax for Razor is geared for minimal typing, plus some progressive detection of where a script block/expression starts and ends. This results in a much leaner syntax than the typical ASP.NET Web Forms alligator (<% %>) tags. Razor uses the @ sign plus standard C# (or Visual Basic) block syntax to delineate code snippets and expressions. Here’s a very simple example of what Razor markup looks like along with some comment annotations: <!DOCTYPE html> <html>     <head>         <title></title>     </head>     <body>     <h1>Razor Test</h1>          <!-- simple expressions -->     @DateTime.Now     <hr />     <!-- method expressions -->     @DateTime.Now.ToString("T")          <!-- code blocks -->     @{         List<string> names = new List<string>();         names.Add("Rick");         names.Add("Markus");         names.Add("Claudio");         names.Add("Kevin");     }          <!-- structured block statements -->     <ul>     @foreach(string name in names){             <li>@name</li>     }     </ul>           <!-- Conditional code -->        @if(true) {                        <!-- Literal Text embedding in code -->        <text>         true        </text>;    }    else    {        <!-- Literal Text embedding in code -->       <text>       false       </text>;    }    </body> </html> Like the Web Forms view engine, Razor parses pages into code, and then executes that run-time compiled code. Effectively a “page” becomes a code file with markup becoming literal text written into the Response stream, code snippets becoming raw code, and expressions being written out with Response.Write(). The code generated from Razor doesn’t look much different from similar Web Forms code that only uses script tags; so although the syntax may look different, the operational model is fairly similar to the Web Forms engine minus the overhead of the large Page object model. However, there are differences: -Razor pages are based on a new base class, Microsoft.WebPages.WebPage, which is hosted in the Microsoft.WebPages assembly that houses all the Razor engine parsing and processing logic. Browsing through the assembly (in the generated ASP.NET Temporary Files folder or GAC) will give you a good idea of the functionality that Razor provides. If you look closely, a lot of the feature set matches ASP.NET MVC’s view implementation as well as many of the helper classes found in MVC. It’s not hard to guess the motivation for this sort of view engine: For beginning developers the simple markup syntax is easier to work with, although you obviously still need to have some understanding of the .NET Framework in order to create dynamic content. The syntax is easier to read and grok and much shorter to type than ASP.NET alligator tags (<% %>) and also easier to understand aesthetically what’s happening in the markup code. Razor also is a better fit for Microsoft’s vision of ASP.NET MVC: It’s a new view engine without the baggage of Web Forms attached to it. The engine is more lightweight since it doesn’t carry all the features and object model of Web Forms with it and it can be instantiated directly outside of the HTTP environment, which has been rather tricky to do for the Web Forms view engine. Having a standalone script parser is a huge win for other applications as well – it makes it much easier to create script or meta driven output generators for many types of applications from code/screen generators, to simple form letters to data merging applications with user customizability. For me personally this is very useful side effect and who knows maybe Microsoft will actually standardize they’re scripting engines (die T4 die!) on this engine. Razor also better fits the “view-based” approach where the view is supposed to be mostly a visual representation that doesn’t hold much, if any, code. While you can still use code, the code you do write has to be self-contained. Overall I wouldn’t be surprised if Razor will become the new standard view engine for MVC in the future – and in fact there have been announcements recently that Razor will become the default script engine in ASP.NET MVC 3.0. Razor can also be used in existing Web Forms and MVC applications, although that’s not working currently unless you manually configure the script mappings and add the appropriate assemblies. It’s possible to do it, but it’s probably better to wait until Microsoft releases official support for Razor scripts in Visual Studio. Once that happens, you can simply drop .cshtml and .vbhtml pages into an existing ASP.NET project and they will work side by side with classic ASP.NET pages. WebMatrix Development Environment To tie all of these three technologies together, Microsoft is shipping WebMatrix with an integrated development environment. An integrated gallery manager makes it easy to download and load existing projects, and then extend them with custom functionality. It seems to be a prominent goal to provide community-oriented content that can act as a starting point, be it via a custom templates or a complete standard application. The IDE includes a project manager that works with a single project and provides an integrated IDE/editor for editing the .cshtml and .vbhtml pages. A run button allows you to quickly run pages in the project manager in a variety of browsers. There’s no debugging support for code at this time. Note that Razor pages don’t require explicit compilation, so making a change, saving, and then refreshing your page in the browser is all that’s needed to see changes while testing an application locally. It’s essentially using the auto-compiling Web Project that was introduced with .NET 2.0. All code is compiled during run time into dynamically created assemblies in the ASP.NET temp folder. WebMatrix also has PHP Editing support with syntax highlighting. You can load various PHP-based applications from the WebMatrix Web Gallery directly into the IDE. Most of the Web Gallery applications are ready to install and run without further configuration, with Wizards taking you through installation of tools, dependencies, and configuration of the database as needed. WebMatrix leverages the Web Platform installer to pull the pieces down from websites in a tight integration of tools that worked nicely for the four or five applications I tried this out on. Click a couple of check boxes and fill in a few simple configuration options and you end up with a running application that’s ready to be customized. Nice! You can easily deploy completed applications via WebDeploy (to an IIS server) or FTP directly from within the development environment. The deploy tool also can handle automatically uploading and installing the database and all related assemblies required, making deployment a simple one-click install step. Simplified Database Access The IDE contains a database editor that can edit SQL Compact and SQL Server databases. There is also a Database helper class that facilitates database access by providing easy-to-use, high-level query execution and iteration methods: @{       var db = Database.OpenFile("FirstApp.sdf");     string sql = "select * from customers where Id > @0"; } <ul> @foreach(var row in db.Query(sql,1)){         <li>@row.FirstName @row.LastName</li> } </ul> The query function takes a SQL statement plus any number of positional (@0,@1 etc.) SQL parameters by simple values. The result is returned as a collection of rows which in turn have a row object with dynamic properties for each of the columns giving easy (though untyped) access to each of the fields. Likewise Execute and ExecuteNonQuery allow execution of more complex queries using similar parameter passing schemes. Note these queries use string-based queries rather than LINQ or Entity Framework’s strongly typed LINQ queries. While this may seem like a step back, it’s also in line with the expectations of non .NET script developers who are quite used to writing and using SQL strings in code rather than using OR/M frameworks. The only question is why was something not included from the beginning in .NET and Microsoft made developers build custom implementations of these basic building blocks. The implementation looks a lot like a DataTable-style data access mechanism, but to be fair, this is a common approach in scripting languages. This type of syntax that uses simple, static, data object methods to perform simple data tasks with one line of code are common in scripting languages and are a good match for folks working in PHP/Python, etc. Seems like Microsoft has taken great advantage of .NET 4.0’s dynamic typing to provide this sort of interface for row iteration where each row has properties for each field. FWIW, all the examples demonstrate using local SQL Compact files - I was unable to get a SQL Server connection string to work with the Database class (the connection string wasn’t accepted). However, since the code in the page is still plain old .NET, you can easily use standard ADO.NET code or even LINQ or Entity Framework models that are created outside of WebMatrix in separate assemblies as required. The good the bad the obnoxious - It’s still .NET The beauty (or curse depending on how you look at it :)) of Razor and the compilation model is that, behind it all, it’s still .NET. Although the syntax may look foreign, it’s still all .NET behind the scenes. You can easily access existing tools, helpers, and utilities simply by adding them to the project as references or to the bin folder. Razor automatically recognizes any assembly reference from assemblies in the bin folder. In the default configuration, Microsoft provides a host of helper functions in a Microsoft.WebPages assembly (check it out in the ASP.NET temp folder for your application), which includes a host of HTML Helpers. If you’ve used ASP.NET MVC before, a lot of the helpers should look familiar. Documentation at the moment is sketchy-there’s a very rough API reference you can check out here: http://www.asp.net/webmatrix/tutorials/asp-net-web-pages-api-reference Who needs WebMatrix? Uhm… good Question Clearly Microsoft is trying hard to create an environment with WebMatrix that is easy to use for newbie developers. The goal seems to be simplicity in providing a minimal development environment and an easy-to-use script engine/language that makes it easy to get started with. There’s also some focus on community features that can be used as starting points, such as Web Gallery applications and templates. The community features in particular are very nice and something that would be nice to eventually see in Visual Studio as well. The question is whether this is too little too late. Developers who have been clamoring for a simpler development environment on the .NET stack have mostly left for other simpler platforms like PHP or Python which are catering to the down and dirty developer. Microsoft will be hard pressed to win those folks-and other hardcore PHP developers-back. Regardless of how much you dress up a script engine fronted by the .NET Framework, it’s still the .NET Framework and all the complexity that drives it. While .NET is a fine solution in its breadth and features once you get a basic handle on the core features, the bar of entry to being productive with the .NET Framework is still pretty high. The MVC style helpers Microsoft provides are a good step in the right direction, but I suspect it’s not enough to shield new developers from having to delve much deeper into the Framework to get even basic applications built. Razor and its helpers is trying to make .NET more accessible but the reality is that in order to do useful stuff that goes beyond the handful of simple helpers you still are going to have to write some C# or VB or other .NET code. If the target is a hobby/amateur/non-programmer the learning curve isn’t made any easier by WebMatrix it’s just been shifted a tad bit further along in your development endeavor when you run out of canned components that are supplied either by Microsoft or the community. The database helpers are interesting and actually I’ve heard a lot of discussion from various developers who’ve been resisting .NET for a really long time perking up at the prospect of easier data access in .NET than the ridiculous amount of code it takes to do even simple data access with raw ADO.NET. It seems sad that such a simple concept and implementation should trigger this sort of response (especially since it’s practically trivial to create helpers like these or pick them up from countless libraries available), but there it is. It also shows that there are plenty of developers out there who are more interested in ‘getting stuff done’ easily than necessarily following the latest and greatest practices which are overkill for many development scenarios. Sometimes it seems that all of .NET is focused on the big life changing issues of development, rather than the bread and butter scenarios that many developers are interested in to get their work accomplished. And that in the end may be WebMatrix’s main raison d'être: To bring some focus back at Microsoft that simpler and more high level solutions are actually needed to appeal to the non-high end developers as well as providing the necessary tools for the high end developers who want to follow the latest and greatest trends. The current version of WebMatrix hits many sweet spots, but it also feels like it has a long way to go before it really can be a tool that a beginning developer or an accomplished developer can feel comfortable with. Although there are some really good ideas in the environment (like the gallery for downloading apps and components) which would be a great addition for Visual Studio as well, the rest of the development environment just feels like crippleware with required functionality missing especially debugging and Intellisense, but also general editor support. It’s not clear whether these are because the product is still in an early alpha release or whether it’s simply designed that way to be a really limited development environment. While simple can be good, nobody wants to feel left out when it comes to necessary tool support and WebMatrix just has that left out feeling to it. If anything WebMatrix’s technology pieces (which are really independent of the WebMatrix product) are what are interesting to developers in general. The compact IIS implementation is a nice improvement for development scenarios and SQL Compact 4.0 seems to address a lot of concerns that people have had and have complained about for some time with previous SQL Compact implementations. By far the most interesting and useful technology though seems to be the Razor view engine for its light weight implementation and it’s decoupling from the ASP.NET/HTTP pipeline to provide a standalone scripting/view engine that is pluggable. The first winner of this is going to be ASP.NET MVC which can now have a cleaner view model that isn’t inconsistent due to the baggage of non-implemented WebForms features that don’t work in MVC. But I expect that Razor will end up in many other applications as a scripting and code generation engine eventually. Visual Studio integration for Razor is currently missing, but is promised for a later release. The ASP.NET MVC team has already mentioned that Razor will eventually become the default MVC view engine, which will guarantee continued growth and development of this tool along those lines. And the Razor engine and support tools actually inherit many of the features that MVC pioneered, so there’s some synergy flowing both ways between Razor and MVC. As an existing ASP.NET developer who’s already familiar with Visual Studio and ASP.NET development, the WebMatrix IDE doesn’t give you anything that you want. The tools provided are minimal and provide nothing that you can’t get in Visual Studio today, except the minimal Razor syntax highlighting, so there’s little need to take a step back. With Visual Studio integration coming later there’s little reason to look at WebMatrix for tooling. It’s good to see that Microsoft is giving some thought about the ease of use of .NET as a platform For so many years, we’ve been piling on more and more new features without trying to take a step back and see how complicated the development/configuration/deployment process has become. Sometimes it’s good to take a step - or several steps - back and take another look and realize just how far we’ve come. WebMatrix is one of those reminders and one that likely will result in some positive changes on the platform as a whole. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET   IIS7  

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  • Dynamically loading Assemblies to reduce Runtime Depencies

    - by Rick Strahl
    I've been working on a request to the West Wind Application Configuration library to add JSON support. The config library is a very easy to use code-first approach to configuration: You create a class that holds the configuration data that inherits from a base configuration class, and then assign a persistence provider at runtime that determines where and how the configuration data is store. Currently the library supports .NET Configuration stores (web.config/app.config), XML files, SQL records and string storage.About once a week somebody asks me about JSON support and I've deflected this question for the longest time because frankly I think that JSON as a configuration store doesn't really buy a heck of a lot over XML. Both formats require the user to perform some fixup of the plain configuration data - in XML into XML tags, with JSON using JSON delimiters for properties and property formatting rules. Sure JSON is a little less verbose and maybe a little easier to read if you have hierarchical data, but overall the differences are pretty minor in my opinion. And yet - the requests keep rolling in.Hard Link Issues in a Component LibraryAnother reason I've been hesitant is that I really didn't want to pull in a dependency on an external JSON library - in this case JSON.NET - into the core library. If you're not using JSON.NET elsewhere I don't want a user to have to require a hard dependency on JSON.NET unless they want to use the JSON feature. JSON.NET is also sensitive to versions and doesn't play nice with multiple versions when hard linked. For example, when you have a reference to V4.4 in your project but the host application has a reference to version 4.5 you can run into assembly load problems. NuGet's Update-Package can solve some of this *if* you can recompile, but that's not ideal for a component that's supposed to be just plug and play. This is no criticism of JSON.NET - this really applies to any dependency that might change.  So hard linking the DLL can be problematic for a number reasons, but the primary reason is to not force loading of JSON.NET unless you actually need it when you use the JSON configuration features of the library.Enter Dynamic LoadingSo rather than adding an assembly reference to the project, I decided that it would be better to dynamically load the DLL at runtime and then use dynamic typing to access various classes. This allows me to run without a hard assembly reference and allows more flexibility with version number differences now and in the future.But there are also a couple of downsides:No assembly reference means only dynamic access - no compiler type checking or IntellisenseRequirement for the host application to have reference to JSON.NET or else get runtime errorsThe former is minor, but the latter can be problematic. Runtime errors are always painful, but in this case I'm willing to live with this. If you want to use JSON configuration settings JSON.NET needs to be loaded in the project. If this is a Web project, it'll likely be there already.So there are a few things that are needed to make this work:Dynamically create an instance and optionally attempt to load an Assembly (if not loaded)Load types into dynamic variablesUse Reflection for a few tasks like statics/enumsThe dynamic keyword in C# makes the formerly most difficult Reflection part - method calls and property assignments - fairly painless. But as cool as dynamic is it doesn't handle all aspects of Reflection. Specifically it doesn't deal with object activation, truly dynamic (string based) member activation or accessing of non instance members, so there's still a little bit of work left to do with Reflection.Dynamic Object InstantiationThe first step in getting the process rolling is to instantiate the type you need to work with. This might be a two step process - loading the instance from a string value, since we don't have a hard type reference and potentially having to load the assembly. Although the host project might have a reference to JSON.NET, that instance might have not been loaded yet since it hasn't been accessed yet. In ASP.NET this won't be a problem, since ASP.NET preloads all referenced assemblies on AppDomain startup, but in other executable project, assemblies are just in time loaded only when they are accessed.Instantiating a type is a two step process: Finding the type reference and then activating it. Here's the generic code out of my ReflectionUtils library I use for this:/// <summary> /// Creates an instance of a type based on a string. Assumes that the type's /// </summary> /// <param name="typeName">Common name of the type</param> /// <param name="args">Any constructor parameters</param> /// <returns></returns> public static object CreateInstanceFromString(string typeName, params object[] args) { object instance = null; Type type = null; try { type = GetTypeFromName(typeName); if (type == null) return null; instance = Activator.CreateInstance(type, args); } catch { return null; } return instance; } /// <summary> /// Helper routine that looks up a type name and tries to retrieve the /// full type reference in the actively executing assemblies. /// </summary> /// <param name="typeName"></param> /// <returns></returns> public static Type GetTypeFromName(string typeName) { Type type = null; // Let default name binding find it type = Type.GetType(typeName, false); if (type != null) return type; // look through assembly list var assemblies = AppDomain.CurrentDomain.GetAssemblies(); // try to find manually foreach (Assembly asm in assemblies) { type = asm.GetType(typeName, false); if (type != null) break; } return type; } To use this for loading JSON.NET I have a small factory function that instantiates JSON.NET and sets a bunch of configuration settings on the generated object. The startup code also looks for failure and tries loading up the assembly when it fails since that's the main reason the load would fail. Finally it also caches the loaded instance for reuse (according to James the JSON.NET instance is thread safe and quite a bit faster when cached). Here's what the factory function looks like in JsonSerializationUtils:/// <summary> /// Dynamically creates an instance of JSON.NET /// </summary> /// <param name="throwExceptions">If true throws exceptions otherwise returns null</param> /// <returns>Dynamic JsonSerializer instance</returns> public static dynamic CreateJsonNet(bool throwExceptions = true) { if (JsonNet != null) return JsonNet; lock (SyncLock) { if (JsonNet != null) return JsonNet; // Try to create instance dynamic json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); if (json == null) { try { var ass = AppDomain.CurrentDomain.Load("Newtonsoft.Json"); json = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.JsonSerializer"); } catch (Exception ex) { if (throwExceptions) throw; return null; } } if (json == null) return null; json.ReferenceLoopHandling = (dynamic) ReflectionUtils.GetStaticProperty("Newtonsoft.Json.ReferenceLoopHandling", "Ignore"); // Enums as strings in JSON dynamic enumConverter = ReflectionUtils.CreateInstanceFromString("Newtonsoft.Json.Converters.StringEnumConverter"); json.Converters.Add(enumConverter); JsonNet = json; } return JsonNet; }This code's purpose is to return a fully configured JsonSerializer instance. As you can see the code tries to create an instance and when it fails tries to load the assembly, and then re-tries loading.Once the instance is loaded some configuration occurs on it. Specifically I set the ReferenceLoopHandling option to not blow up immediately when circular references are encountered. There are a host of other small config setting that might be useful to set, but the default seem to be good enough in recent versions. Note that I'm setting ReferenceLoopHandling which requires an Enum value to be set. There's no real easy way (short of using the cardinal numeric value) to set a property or pass parameters from static values or enums. This means I still need to use Reflection to make this work. I'm using the same ReflectionUtils class I previously used to handle this for me. The function looks up the type and then uses Type.InvokeMember() to read the static property.Another feature I need is have Enum values serialized as strings rather than numeric values which is the default. To do this I can use the StringEnumConverter to convert enums to strings by adding it to the Converters collection.As you can see there's still a bit of Reflection to be done even in C# 4+ with dynamic, but with a few helpers this process is relatively painless.Doing the actual JSON ConversionFinally I need to actually do my JSON conversions. For the Utility class I need serialization that works for both strings and files so I created four methods that handle these tasks two each for serialization and deserialization for string and file.Here's what the File Serialization looks like:/// <summary> /// Serializes an object instance to a JSON file. /// </summary> /// <param name="value">the value to serialize</param> /// <param name="fileName">Full path to the file to write out with JSON.</param> /// <param name="throwExceptions">Determines whether exceptions are thrown or false is returned</param> /// <param name="formatJsonOutput">if true pretty-formats the JSON with line breaks</param> /// <returns>true or false</returns> public static bool SerializeToFile(object value, string fileName, bool throwExceptions = false, bool formatJsonOutput = false) { dynamic writer = null; FileStream fs = null; try { Type type = value.GetType(); var json = CreateJsonNet(throwExceptions); if (json == null) return false; fs = new FileStream(fileName, FileMode.Create); var sw = new StreamWriter(fs, Encoding.UTF8); writer = Activator.CreateInstance(JsonTextWriterType, sw); if (formatJsonOutput) writer.Formatting = (dynamic)Enum.Parse(FormattingType, "Indented"); writer.QuoteChar = '"'; json.Serialize(writer, value); } catch (Exception ex) { Debug.WriteLine("JsonSerializer Serialize error: " + ex.Message); if (throwExceptions) throw; return false; } finally { if (writer != null) writer.Close(); if (fs != null) fs.Close(); } return true; }You can see more of the dynamic invocation in this code. First I grab the dynamic JsonSerializer instance using the CreateJsonNet() method shown earlier which returns a dynamic. I then create a JsonTextWriter and configure a couple of enum settings on it, and then call Serialize() on the serializer instance with the JsonTextWriter that writes the output to disk. Although this code is dynamic it's still fairly short and readable.For full circle operation here's the DeserializeFromFile() version:/// <summary> /// Deserializes an object from file and returns a reference. /// </summary> /// <param name="fileName">name of the file to serialize to</param> /// <param name="objectType">The Type of the object. Use typeof(yourobject class)</param> /// <param name="binarySerialization">determines whether we use Xml or Binary serialization</param> /// <param name="throwExceptions">determines whether failure will throw rather than return null on failure</param> /// <returns>Instance of the deserialized object or null. Must be cast to your object type</returns> public static object DeserializeFromFile(string fileName, Type objectType, bool throwExceptions = false) { dynamic json = CreateJsonNet(throwExceptions); if (json == null) return null; object result = null; dynamic reader = null; FileStream fs = null; try { fs = new FileStream(fileName, FileMode.Open, FileAccess.Read); var sr = new StreamReader(fs, Encoding.UTF8); reader = Activator.CreateInstance(JsonTextReaderType, sr); result = json.Deserialize(reader, objectType); reader.Close(); } catch (Exception ex) { Debug.WriteLine("JsonNetSerialization Deserialization Error: " + ex.Message); if (throwExceptions) throw; return null; } finally { if (reader != null) reader.Close(); if (fs != null) fs.Close(); } return result; }This code is a little more compact since there are no prettifying options to set. Here JsonTextReader is created dynamically and it receives the output from the Deserialize() operation on the serializer.You can take a look at the full JsonSerializationUtils.cs file on GitHub to see the rest of the operations, but the string operations are very similar - the code is fairly repetitive.These generic serialization utilities isolate the dynamic serialization logic that has to deal with the dynamic nature of JSON.NET, and any code that uses these functions is none the wiser that JSON.NET is dynamically loaded.Using the JsonSerializationUtils WrapperThe final consumer of the SerializationUtils wrapper is an actual ConfigurationProvider, that is responsible for handling reading and writing JSON values to and from files. The provider is simple a small wrapper around the SerializationUtils component and there's very little code to make this work now:The whole provider looks like this:/// <summary> /// Reads and Writes configuration settings in .NET config files and /// sections. Allows reading and writing to default or external files /// and specification of the configuration section that settings are /// applied to. /// </summary> public class JsonFileConfigurationProvider<TAppConfiguration> : ConfigurationProviderBase<TAppConfiguration> where TAppConfiguration: AppConfiguration, new() { /// <summary> /// Optional - the Configuration file where configuration settings are /// stored in. If not specified uses the default Configuration Manager /// and its default store. /// </summary> public string JsonConfigurationFile { get { return _JsonConfigurationFile; } set { _JsonConfigurationFile = value; } } private string _JsonConfigurationFile = string.Empty; public override bool Read(AppConfiguration config) { var newConfig = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfiguration)) as TAppConfiguration; if (newConfig == null) { if(Write(config)) return true; return false; } DecryptFields(newConfig); DataUtils.CopyObjectData(newConfig, config, "Provider,ErrorMessage"); return true; } /// <summary> /// Return /// </summary> /// <typeparam name="TAppConfig"></typeparam> /// <returns></returns> public override TAppConfig Read<TAppConfig>() { var result = JsonSerializationUtils.DeserializeFromFile(JsonConfigurationFile, typeof(TAppConfig)) as TAppConfig; if (result != null) DecryptFields(result); return result; } /// <summary> /// Write configuration to XmlConfigurationFile location /// </summary> /// <param name="config"></param> /// <returns></returns> public override bool Write(AppConfiguration config) { EncryptFields(config); bool result = JsonSerializationUtils.SerializeToFile(config, JsonConfigurationFile,false,true); // Have to decrypt again to make sure the properties are readable afterwards DecryptFields(config); return result; } }This incidentally demonstrates how easy it is to create a new provider for the West Wind Application Configuration component. Simply implementing 3 methods will do in most cases.Note this code doesn't have any dynamic dependencies - all that's abstracted away in the JsonSerializationUtils(). From here on, serializing JSON is just a matter of calling the static methods on the SerializationUtils class.Already, there are several other places in some other tools where I use JSON serialization this is coming in very handy. With a couple of lines of code I was able to add JSON.NET support to an older AJAX library that I use replacing quite a bit of code that was previously in use. And for any other manual JSON operations (in a couple of apps I use JSON Serialization for 'blob' like document storage) this is also going to be handy.Performance?Some of you might be thinking that using dynamic and Reflection can't be good for performance. And you'd be right… In performing some informal testing it looks like the performance of the native code is nearly twice as fast as the dynamic code. Most of the slowness is attributable to type lookups. To test I created a native class that uses an actual reference to JSON.NET and performance was consistently around 85-90% faster with the referenced code. That being said though - I serialized 10,000 objects in 80ms vs. 45ms so this isn't hardly slouchy. For the configuration component speed is not that important because both read and write operations typically happen once on first access and then every once in a while. But for other operations - say a serializer trying to handle AJAX requests on a Web Server one would be well served to create a hard dependency.Dynamic Loading - Worth it?On occasion dynamic loading makes sense. But there's a price to be paid in added code complexity and a performance hit. But for some operations that are not pivotal to a component or application and only used under certain circumstances dynamic loading can be beneficial to avoid having to ship extra files and loading down distributions. These days when you create new projects in Visual Studio with 30 assemblies before you even add your own code, trying to keep file counts under control seems a good idea. It's not the kind of thing you do on a regular basis, but when needed it can be a useful tool. Hopefully some of you find this information useful…© Rick Strahl, West Wind Technologies, 2005-2013Posted in .NET  C#   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Asynchronous Streaming in ASP.NET WebApi

    - by andresv
     Hi everyone, if you use the cool MVC4 WebApi you might encounter yourself in a common situation where you need to return a rather large amount of data (most probably from a database) and you want to accomplish two things: Use streaming so the client fetch the data as needed, and that directly correlates to more fetching in the server side (from our database, for example) without consuming large amounts of memory. Leverage the new MVC4 WebApi and .NET 4.5 async/await asynchronous execution model to free ASP.NET Threadpool threads (if possible).  So, #1 and #2 are not directly related to each other and we could implement our code fulfilling one or the other, or both. The main point about #1 is that we want our method to immediately return to the caller a stream, and that client side stream be represented by a server side stream that gets written (and its related database fetch) only when needed. In this case we would need some form of "state machine" that keeps running in the server and "knows" what is the next thing to fetch into the output stream when the client ask for more content. This technique is generally called a "continuation" and is nothing new in .NET, in fact using an IEnumerable<> interface and the "yield return" keyword does exactly that, so our first impulse might be to write our WebApi method more or less like this:           public IEnumerable<Metadata> Get([FromUri] int accountId)         {             // Execute the command and get a reader             using (var reader = GetMetadataListReader(accountId))             {                 // Read rows asynchronously, put data into buffer and write asynchronously                 while (reader.Read())                 {                     yield return MapRecord(reader);                 }             }         }   While the above method works, unfortunately it doesn't accomplish our objective of returning immediately to the caller, and that's because the MVC WebApi infrastructure doesn't yet recognize our intentions and when it finds an IEnumerable return value, enumerates it before returning to the client its values. To prove my point, I can code a test method that calls this method, for example:        [TestMethod]         public void StreamedDownload()         {             var baseUrl = @"http://localhost:57771/api/metadata/1";             var client = new HttpClient();             var sw = Stopwatch.StartNew();             var stream = client.GetStreamAsync(baseUrl).Result;             sw.Stop();             Debug.WriteLine("Elapsed time Call: {0}ms", sw.ElapsedMilliseconds); } So, I would expect the line "var stream = client.GetStreamAsync(baseUrl).Result" returns immediately without server-side fetching of all data in the database reader, and this didn't happened. To make the behavior more evident, you could insert a wait time (like Thread.Sleep(1000);) inside the "while" loop, and you will see that the client call (GetStreamAsync) is not going to return control after n seconds (being n == number of reader records being fetched).Ok, we know this doesn't work, and the question would be: is there a way to do it?Fortunately, YES!  and is not very difficult although a little more convoluted than our simple IEnumerable return value. Maybe in the future this scenario will be automatically detected and supported in MVC/WebApi.The solution to our needs is to use a very handy class named PushStreamContent and then our method signature needs to change to accommodate this, returning an HttpResponseMessage instead of our previously used IEnumerable<>. The final code will be something like this: public HttpResponseMessage Get([FromUri] int accountId)         {             HttpResponseMessage response = Request.CreateResponse();             // Create push content with a delegate that will get called when it is time to write out              // the response.             response.Content = new PushStreamContent(                 async (outputStream, httpContent, transportContext) =>                 {                     try                     {                         // Execute the command and get a reader                         using (var reader = GetMetadataListReader(accountId))                         {                             // Read rows asynchronously, put data into buffer and write asynchronously                             while (await reader.ReadAsync())                             {                                 var rec = MapRecord(reader);                                 var str = await JsonConvert.SerializeObjectAsync(rec);                                 var buffer = UTF8Encoding.UTF8.GetBytes(str);                                 // Write out data to output stream                                 await outputStream.WriteAsync(buffer, 0, buffer.Length);                             }                         }                     }                     catch(HttpException ex)                     {                         if (ex.ErrorCode == -2147023667) // The remote host closed the connection.                          {                             return;                         }                     }                     finally                     {                         // Close output stream as we are done                         outputStream.Close();                     }                 });             return response;         } As an extra bonus, all involved classes used already support async/await asynchronous execution model, so taking advantage of that was very easy. Please note that the PushStreamContent class receives in its constructor a lambda (specifically an Action) and we decorated our anonymous method with the async keyword (not a very well known technique but quite handy) so we can await over the I/O intensive calls we execute like reading from the database reader, serializing our entity and finally writing to the output stream.  Well, if we execute the test again we will immediately notice that the a line returns immediately and then the rest of the server code is executed only when the client reads through the obtained stream, therefore we get low memory usage and far greater scalability for our beloved application serving big chunks of data.Enjoy!Andrés.        

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  • Using the ASP.NET Cache to cache data in a Model or Business Object layer, without a dependency on System.Web in the layer - Part One.

    - by Rhames
    ASP.NET applications can make use of the System.Web.Caching.Cache object to cache data and prevent repeated expensive calls to a database or other store. However, ideally an application should make use of caching at the point where data is retrieved from the database, which typically is inside a Business Objects or Model layer. One of the key features of using a UI pattern such as Model-View-Presenter (MVP) or Model-View-Controller (MVC) is that the Model and Presenter (or Controller) layers are developed without any knowledge of the UI layer. Introducing a dependency on System.Web into the Model layer would break this independence of the Model from the View. This article gives a solution to this problem, using dependency injection to inject the caching implementation into the Model layer at runtime. This allows caching to be used within the Model layer, without any knowledge of the actual caching mechanism that will be used. Create a sample application to use the caching solution Create a test SQL Server database This solution uses a SQL Server database with the same Sales data used in my previous post on calculating running totals. The advantage of using this data is that it gives nice slow queries that will exaggerate the effect of using caching! To create the data, first create a new SQL database called CacheSample. Next run the following script to create the Sale table and populate it: USE CacheSample GO   CREATE TABLE Sale(DayCount smallint, Sales money) CREATE CLUSTERED INDEX ndx_DayCount ON Sale(DayCount) go INSERT Sale VALUES (1,120) INSERT Sale VALUES (2,60) INSERT Sale VALUES (3,125) INSERT Sale VALUES (4,40)   DECLARE @DayCount smallint, @Sales money SET @DayCount = 5 SET @Sales = 10   WHILE @DayCount < 5000  BEGIN  INSERT Sale VALUES (@DayCount,@Sales)  SET @DayCount = @DayCount + 1  SET @Sales = @Sales + 15  END Next create a stored procedure to calculate the running total, and return a specified number of rows from the Sale table, using the following script: USE [CacheSample] GO   SET ANSI_NULLS ON GO   SET QUOTED_IDENTIFIER ON GO   -- ============================================= -- Author:        Robin -- Create date: -- Description:   -- ============================================= CREATE PROCEDURE [dbo].[spGetRunningTotals]       -- Add the parameters for the stored procedure here       @HighestDayCount smallint = null AS BEGIN       -- SET NOCOUNT ON added to prevent extra result sets from       -- interfering with SELECT statements.       SET NOCOUNT ON;         IF @HighestDayCount IS NULL             SELECT @HighestDayCount = MAX(DayCount) FROM dbo.Sale                   DECLARE @SaleTbl TABLE (DayCount smallint, Sales money, RunningTotal money)         DECLARE @DayCount smallint,                   @Sales money,                   @RunningTotal money         SET @RunningTotal = 0       SET @DayCount = 0         DECLARE rt_cursor CURSOR       FOR       SELECT DayCount, Sales       FROM Sale       ORDER BY DayCount         OPEN rt_cursor         FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales         WHILE @@FETCH_STATUS = 0 AND @DayCount <= @HighestDayCount        BEGIN        SET @RunningTotal = @RunningTotal + @Sales        INSERT @SaleTbl VALUES (@DayCount,@Sales,@RunningTotal)        FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales        END         CLOSE rt_cursor       DEALLOCATE rt_cursor         SELECT DayCount, Sales, RunningTotal       FROM @SaleTbl   END   GO   Create the Sample ASP.NET application In Visual Studio create a new solution and add a class library project called CacheSample.BusinessObjects and an ASP.NET web application called CacheSample.UI. The CacheSample.BusinessObjects project will contain a single class to represent a Sale data item, with all the code to retrieve the sales from the database included in it for simplicity (normally I would at least have a separate Repository or other object that is responsible for retrieving data, and probably a data access layer as well, but for this sample I want to keep it simple). The C# code for the Sale class is shown below: using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient;   namespace CacheSample.BusinessObjects {     public class Sale     {         public Int16 DayCount { get; set; }         public decimal Sales { get; set; }         public decimal RunningTotal { get; set; }           public static IEnumerable<Sale> GetSales(int? highestDayCount)         {             List<Sale> sales = new List<Sale>();               SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt);             if (highestDayCount.HasValue)                 highestDayCountParameter.Value = highestDayCount;             else                 highestDayCountParameter.Value = DBNull.Value;               string connectionStr = System.Configuration.ConfigurationManager .ConnectionStrings["CacheSample"].ConnectionString;               using(SqlConnection sqlConn = new SqlConnection(connectionStr))             using (SqlCommand sqlCmd = sqlConn.CreateCommand())             {                 sqlCmd.CommandText = "spGetRunningTotals";                 sqlCmd.CommandType = CommandType.StoredProcedure;                 sqlCmd.Parameters.Add(highestDayCountParameter);                   sqlConn.Open();                   using (SqlDataReader dr = sqlCmd.ExecuteReader())                 {                     while (dr.Read())                     {                         Sale newSale = new Sale();                         newSale.DayCount = dr.GetInt16(0);                         newSale.Sales = dr.GetDecimal(1);                         newSale.RunningTotal = dr.GetDecimal(2);                           sales.Add(newSale);                     }                 }             }               return sales;         }     } }   The static GetSale() method makes a call to the spGetRunningTotals stored procedure and then reads each row from the returned SqlDataReader into an instance of the Sale class, it then returns a List of the Sale objects, as IEnnumerable<Sale>. A reference to System.Configuration needs to be added to the CacheSample.BusinessObjects project so that the connection string can be read from the web.config file. In the CacheSample.UI ASP.NET project, create a single web page called ShowSales.aspx, and make this the default start up page. This page will contain a single button to call the GetSales() method and a label to display the results. The html mark up and the C# code behind are shown below: ShowSales.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ShowSales.aspx.cs" Inherits="CacheSample.UI.ShowSales" %>   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">   <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server">     <title>Cache Sample - Show All Sales</title> </head> <body>     <form id="form1" runat="server">     <div>         <asp:Button ID="btnTest1" runat="server" onclick="btnTest1_Click"             Text="Get All Sales" />         &nbsp;&nbsp;&nbsp;         <asp:Label ID="lblResults" runat="server"></asp:Label>         </div>     </form> </body> </html>   ShowSales.aspx.cs using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls;   using CacheSample.BusinessObjects;   namespace CacheSample.UI {     public partial class ShowSales : System.Web.UI.Page     {         protected void Page_Load(object sender, EventArgs e)         {         }           protected void btnTest1_Click(object sender, EventArgs e)         {             System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch();             stopWatch.Start();               var sales = Sale.GetSales(null);               var lastSales = sales.Last();               stopWatch.Stop();               lblResults.Text = string.Format( "Count of Sales: {0}, Last DayCount: {1}, Total Sales: {2}. Query took {3} ms", sales.Count(), lastSales.DayCount, lastSales.RunningTotal, stopWatch.ElapsedMilliseconds);         }       } }   Finally we need to add a connection string to the CacheSample SQL Server database, called CacheSample, to the web.config file: <?xmlversion="1.0"?>   <configuration>    <connectionStrings>     <addname="CacheSample"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample"          providerName="System.Data.SqlClient" />  </connectionStrings>    <system.web>     <compilationdebug="true"targetFramework="4.0" />  </system.web>   </configuration>   Run the application and click the button a few times to see how long each call to the database takes. On my system, each query takes about 450ms. Next I shall look at a solution to use the ASP.NET caching to cache the data returned by the query, so that subsequent requests to the GetSales() method are much faster. Adding Data Caching Support I am going to create my caching support in a separate project called CacheSample.Caching, so the next step is to add a class library to the solution. We shall be using the application configuration to define the implementation of our caching system, so we need a reference to System.Configuration adding to the project. ICacheProvider<T> Interface The first step in adding caching to our application is to define an interface, called ICacheProvider, in the CacheSample.Caching project, with methods to retrieve any data from the cache or to retrieve the data from the data source if it is not present in the cache. Dependency Injection will then be used to inject an implementation of this interface at runtime, allowing the users of the interface (i.e. the CacheSample.BusinessObjects project) to be completely unaware of how the caching is actually implemented. As data of any type maybe retrieved from the data source, it makes sense to use generics in the interface, with a generic type parameter defining the data type associated with a particular instance of the cache interface implementation. The C# code for the ICacheProvider interface is shown below: using System; using System.Collections.Generic;   namespace CacheSample.Caching {     public interface ICacheProvider     {     }       public interface ICacheProvider<T> : ICacheProvider     {         T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry);           IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry);     } }   The empty non-generic interface will be used as a type in a Dictionary generic collection later to store instances of the ICacheProvider<T> implementation for reuse, I prefer to use a base interface when doing this, as I think the alternative of using object makes for less clear code. The ICacheProvider<T> interface defines two overloaded Fetch methods, the difference between these is that one will return a single instance of the type T and the other will return an IEnumerable<T>, providing support for easy caching of collections of data items. Both methods will take a key parameter, which will uniquely identify the cached data, a delegate of type Func<T> or Func<IEnumerable<T>> which will provide the code to retrieve the data from the store if it is not present in the cache, and absolute or relative expiry policies to define when a cached item should expire. Note that at present there is no support for cache dependencies, but I shall be showing a method of adding this in part two of this article. CacheProviderFactory Class We need a mechanism of creating instances of our ICacheProvider<T> interface, using Dependency Injection to get the implementation of the interface. To do this we shall create a CacheProviderFactory static class in the CacheSample.Caching project. This factory will provide a generic static method called GetCacheProvider<T>(), which shall return instances of ICacheProvider<T>. We can then call this factory method with the relevant data type (for example the Sale class in the CacheSample.BusinessObject project) to get a instance of ICacheProvider for that type (e.g. call CacheProviderFactory.GetCacheProvider<Sale>() to get the ICacheProvider<Sale> implementation). The C# code for the CacheProviderFactory is shown below: using System; using System.Collections.Generic;   using CacheSample.Caching.Configuration;   namespace CacheSample.Caching {     public static class CacheProviderFactory     {         private static Dictionary<Type, ICacheProvider> cacheProviders = new Dictionary<Type, ICacheProvider>();         private static object syncRoot = new object();           ///<summary>         /// Factory method to create or retrieve an implementation of the  /// ICacheProvider interface for type <typeparamref name="T"/>.         ///</summary>         ///<typeparam name="T">  /// The type that this cache provider instance will work with  ///</typeparam>         ///<returns>An instance of the implementation of ICacheProvider for type  ///<typeparamref name="T"/>, as specified by the application  /// configuration</returns>         public static ICacheProvider<T> GetCacheProvider<T>()         {             ICacheProvider<T> cacheProvider = null;             // Get the Type reference for the type parameter T             Type typeOfT = typeof(T);               // Lock the access to the cacheProviders dictionary             // so multiple threads can work with it             lock (syncRoot)             {                 // First check if an instance of the ICacheProvider implementation  // already exists in the cacheProviders dictionary for the type T                 if (cacheProviders.ContainsKey(typeOfT))                     cacheProvider = (ICacheProvider<T>)cacheProviders[typeOfT];                 else                 {                     // There is not already an instance of the ICacheProvider in       // cacheProviders for the type T                     // so we need to create one                       // Get the Type reference for the application's implementation of       // ICacheProvider from the configuration                     Type cacheProviderType = Type.GetType(CacheProviderConfigurationSection.Current. CacheProviderType);                     if (cacheProviderType != null)                     {                         // Now get a Type reference for the Cache Provider with the                         // type T generic parameter                         Type typeOfCacheProviderTypeForT = cacheProviderType.MakeGenericType(new Type[] { typeOfT });                         if (typeOfCacheProviderTypeForT != null)                         {                             // Create the instance of the Cache Provider and add it to // the cacheProviders dictionary for future use                             cacheProvider = (ICacheProvider<T>)Activator. CreateInstance(typeOfCacheProviderTypeForT);                             cacheProviders.Add(typeOfT, cacheProvider);                         }                     }                 }             }               return cacheProvider;                 }     } }   As this code uses Activator.CreateInstance() to create instances of the ICacheProvider<T> implementation, which is a slow process, the factory class maintains a Dictionary of the previously created instances so that a cache provider needs to be created only once for each type. The type of the implementation of ICacheProvider<T> is read from a custom configuration section in the application configuration file, via the CacheProviderConfigurationSection class, which is described below. CacheProviderConfigurationSection Class The implementation of ICacheProvider<T> will be specified in a custom configuration section in the application’s configuration. To handle this create a folder in the CacheSample.Caching project called Configuration, and add a class called CacheProviderConfigurationSection to this folder. This class will extend the System.Configuration.ConfigurationSection class, and will contain a single string property called CacheProviderType. The C# code for this class is shown below: using System; using System.Configuration;   namespace CacheSample.Caching.Configuration {     internal class CacheProviderConfigurationSection : ConfigurationSection     {         public static CacheProviderConfigurationSection Current         {             get             {                 return (CacheProviderConfigurationSection) ConfigurationManager.GetSection("cacheProvider");             }         }           [ConfigurationProperty("type", IsRequired=true)]         public string CacheProviderType         {             get             {                 return (string)this["type"];             }         }     } }   Adding Data Caching to the Sales Class We now have enough code in place to add caching to the GetSales() method in the CacheSample.BusinessObjects.Sale class, even though we do not yet have an implementation of the ICacheProvider<T> interface. We need to add a reference to the CacheSample.Caching project to CacheSample.BusinessObjects so that we can use the ICacheProvider<T> interface within the GetSales() method. Once the reference is added, we can first create a unique string key based on the method name and the parameter value, so that the same cache key is used for repeated calls to the method with the same parameter values. Then we get an instance of the cache provider for the Sales type, using the CacheProviderFactory, and pass the existing code to retrieve the data from the database as the retrievalMethod delegate in a call to the Cache Provider Fetch() method. The C# code for the modified GetSales() method is shown below: public static IEnumerable<Sale> GetSales(int? highestDayCount) {     string cacheKey = string.Format("CacheSample.BusinessObjects.GetSalesWithCache({0})", highestDayCount);       return CacheSample.Caching.CacheProviderFactory. GetCacheProvider<Sale>().Fetch(cacheKey,         delegate()         {             List<Sale> sales = new List<Sale>();               SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt);             if (highestDayCount.HasValue)                 highestDayCountParameter.Value = highestDayCount;             else                 highestDayCountParameter.Value = DBNull.Value;               string connectionStr = System.Configuration.ConfigurationManager. ConnectionStrings["CacheSample"].ConnectionString;               using (SqlConnection sqlConn = new SqlConnection(connectionStr))             using (SqlCommand sqlCmd = sqlConn.CreateCommand())             {                 sqlCmd.CommandText = "spGetRunningTotals";                 sqlCmd.CommandType = CommandType.StoredProcedure;                 sqlCmd.Parameters.Add(highestDayCountParameter);                   sqlConn.Open();                   using (SqlDataReader dr = sqlCmd.ExecuteReader())                 {                     while (dr.Read())                     {                         Sale newSale = new Sale();                         newSale.DayCount = dr.GetInt16(0);                         newSale.Sales = dr.GetDecimal(1);                         newSale.RunningTotal = dr.GetDecimal(2);                           sales.Add(newSale);                     }                 }             }               return sales;         },         null,         new TimeSpan(0, 10, 0)); }     This example passes the code to retrieve the Sales data from the database to the Cache Provider as an anonymous method, however it could also be written as a lambda. The main advantage of using an anonymous function (method or lambda) is that the code inside the anonymous function can access the parameters passed to the GetSales() method. Finally the absolute expiry is set to null, and the relative expiry set to 10 minutes, to indicate that the cache entry should be removed 10 minutes after the last request for the data. As the ICacheProvider<T> has a Fetch() method that returns IEnumerable<T>, we can simply return the results of the Fetch() method to the caller of the GetSales() method. This should be all that is needed for the GetSales() method to now retrieve data from a cache after the first time the data has be retrieved from the database. Implementing a ASP.NET Cache Provider The final step is to actually implement the ICacheProvider<T> interface, and add the implementation details to the web.config file for the dependency injection. The cache provider implementation needs to have access to System.Web. Therefore it could be placed in the CacheSample.UI project, or in its own project that has a reference to System.Web. Implementing the Cache Provider in a separate project is my favoured approach. Create a new project inside the solution called CacheSample.CacheProvider, and add references to System.Web and CacheSample.Caching to this project. Add a class to the project called AspNetCacheProvider. Make the class a generic class by adding the generic parameter <T> and indicate that the class implements ICacheProvider<T>. The C# code for the AspNetCacheProvider class is shown below: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Caching;   using CacheSample.Caching;   namespace CacheSample.CacheProvider {     public class AspNetCacheProvider<T> : ICacheProvider<T>     {         #region ICacheProvider<T> Members           public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry);         }           public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry);         }           #endregion           #region Helper Methods           private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             U value;             if (!TryGetValue<U>(key, out value))             {                 value = retrieveData();                 if (!absoluteExpiry.HasValue)                     absoluteExpiry = Cache.NoAbsoluteExpiration;                   if (!relativeExpiry.HasValue)                     relativeExpiry = Cache.NoSlidingExpiration;                   HttpContext.Current.Cache.Insert(key, value, null, absoluteExpiry.Value, relativeExpiry.Value);             }             return value;         }           private bool TryGetValue<U>(string key, out U value)         {             object cachedValue = HttpContext.Current.Cache.Get(key);             if (cachedValue == null)             {                 value = default(U);                 return false;             }             else             {                 try                 {                     value = (U)cachedValue;                     return true;                 }                 catch                 {                     value = default(U);                     return false;                 }             }         }           #endregion       } }   The two interface Fetch() methods call a private method called FetchAndCache(). This method first checks for a element in the HttpContext.Current.Cache with the specified cache key, and if so tries to cast this to the specified type (either T or IEnumerable<T>). If the cached element is found, the FetchAndCache() method simply returns it. If it is not found in the cache, the method calls the retrievalMethod delegate to get the data from the data source, and then adds this to the HttpContext.Current.Cache. The final step is to add the AspNetCacheProvider class to the relevant custom configuration section in the CacheSample.UI.Web.Config file. To do this there needs to be a <configSections> element added as the first element in <configuration>. This will match a custom section called <cacheProvider> with the CacheProviderConfigurationSection. Then we add a <cacheProvider> element, with a type property set to the fully qualified assembly name of the AspNetCacheProvider class, as shown below: <?xmlversion="1.0"?>   <configuration>  <configSections>     <sectionname="cacheProvider" type="CacheSample.Base.Configuration.CacheProviderConfigurationSection, CacheSample.Base" />  </configSections>    <connectionStrings>     <addname="CacheSample"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample"          providerName="System.Data.SqlClient" />  </connectionStrings>    <cacheProvidertype="CacheSample.CacheProvider.AspNetCacheProvider`1, CacheSample.CacheProvider, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null">  </cacheProvider>    <system.web>     <compilationdebug="true"targetFramework="4.0" />  </system.web>   </configuration>   One point to note is that the fully qualified assembly name of the AspNetCacheProvider class includes the notation `1 after the class name, which indicates that it is a generic class with a single generic type parameter. The CacheSample.UI project needs to have references added to CacheSample.Caching and CacheSample.CacheProvider so that the actual application is aware of the relevant cache provider implementation. Conclusion After implementing this solution, you should have a working cache provider mechanism, that will allow the middle and data access layers to implement caching support when retrieving data, without any knowledge of the actually caching implementation. If the UI is not ASP.NET based, if for example it is Winforms or WPF, the implementation of ICacheProvider<T> would be written around whatever technology is available. It could even be a standalone caching system that takes full responsibility for adding and removing items from a global store. The next part of this article will show how this caching mechanism may be extended to provide support for cache dependencies, such as the System.Web.Caching.SqlCacheDependency. Another possible extension would be to cache the cache provider implementations instead of storing them in a static Dictionary in the CacheProviderFactory. This would prevent a build up of seldom used cache providers in the application memory, as they could be removed from the cache if not used often enough, although in reality there are probably unlikely to be vast numbers of cache provider implementation instances, as most applications do not have a massive number of business object or model types.

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