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• How to find domain registrar and DNS hosting with good DNSSEC support?

  - by rsp

  Simplified problem I want to buy a domain and make a website that is fully secured with DNSSEC. Background I've been hearing about the insecurity of DNS for years. I've watched all of the talks by Dan Kaminsky and others from DNS exploits to The future of DNS Security Panel. I knew that using DNS without security is a disaster waiting to happen. I followed the development of the DNSSEC standard. I celebrated the key signing ceremony. Everything was on the right track to finally have a secure DNS system in place. And now more than 2 years later I wanted to just do what everyone said I should do: use DNSSEC for a new domain. So I need a domain registrar and a DNS hosting service that supports DNSSEC. Surprisingly it is not that easy to even find out who does support DNSSEC. It was actually much easier to find info on DNSSEC two years ago when everyone was going to support DNSSEC Real Soon Now but now years passed and I hardly see any progress done. I just hope that I was just looking in the wrong places and someone here will explain all of the doubts. I hope that other people who want to have a secure website will also find this question useful. What is needed registrar and DNS servers with full DNSSEC support for .com domains What is not needed IPv6 support Web hosting anything more What I found out so far Go Daddy offers Premium DNS service for additional $36 per year that lets you "Secure up to 5 domains with DNSSEC". easyDNS has DNSSEC available in Beta across all service levels (you need to enable the "beta" flag in configuration) but it doesn't seem to be production ready and judging from the lack of updates it isn't a feature of highest priority (the last update from March 2011 on the easyDNS blog). Name.com - according to The Register (US domain registrar does IPv6, DNSSEC) it has DNSSEC support since 2010 but right now (October 2012) I couldn't find anything related to DNSSEC on their website. Dynadot that is very often recommended doesn't support DNSSEC Namecheap that is also often recommended doesn't support DNSSEC. The support answer from 2011 suggested that it was being added but in 2012 still no ETA is given to customers. DynDNS was supposed to support DNSSEC, I found a link explaining DNSSEC support but it gives 404 Not Found page and offers a search box - when searching for DNSSEC I get "No results were found for your query." GKG was recommended online for DNSSEC support but it's hard to find any information on the level of DNSSEC support - there is a brief explanation on what is DNSSEC and how to sign Delegation Signer records in their FAQ but no information about the level of actual support can be found. Ask Slashdot: Which Registrars Support DNSSEC? from July 2011 - Answers list Go Daddy, DynDNS, GKG, Name.com as registrars that support DNSSEC but: see above. Related questions How to find web hosting that meets my requirements? What is needed to add DNSSEC to my site? DNS hosting better managed by Domain provider or Hosting provider? Registrar with good security, DNS hosting, and DNSSEC and IPv6 resolvers? In no. 1 no one is ever mentioning DNS at all. In no. 2 answers only mention the .se TLD, there are very few answers and they seem very outdated. In no. 3 one answer says "On projects that demand higher security, I might look for a web host that supports DNSSEC" but no more information is provided. The only relevant answers are in no. 4 where easyDNS is recommended by someone who has never used them personally. Meanwhile, as of October 2012, the support of DNSSEC is described as "in beta" on the easyDNS feature list. Another one recommends SiteGround but searching their site for DNSSEC returns no results. Other answers recommend web hosting providers that don't meet the requirement of DNSSEC support. Also the question mentioned above lists 9 very specific requirements other than only DNSSEC (like eg. HTTP-only login cookies, two-factor authentications, no DNS record limits, DNS statistics of queries/day, audit trails etc.) which might have excluded many possible recommendations if one is only interested in DNSSEC support. Conclusions I thought that by the end of 2012 the support of DNSSEC among domain registrars and DNS providers would be nearly universal. I am shocked that the support seems virtually nonexistent. Is this a result of some serious problems with the DNSSEC adoption? Or is it just not a hot topic and no one bothers anymore? According to the DNSSEC Scoreboard roughly about 0.1% of .com domains support DNSSEC. Could that be caused by the lack of DNSSEC support among registrars and DNS providers, is the information too hard to find or maybe no one cares? There is even no "dnssec" tag here. Questions The information is surprisingly hard to find. That is why I am asking for first-hand experience and personal recommendations. Has anyone here actually set up a website with DNSSEC, from the domain registration to the configuration of DNS servers? Can anyone recommend any of the registrars mentioned above? Can anyone recommend any registrar not mentioned above?

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• JavaScript Intellisense Improvements with VS 2010

  - by ScottGu

  This is the twentieth in a series of blog posts I’m doing on the upcoming VS 2010 and .NET 4 release.  Today’s blog post covers some of the nice improvements coming with JavaScript intellisense with VS 2010 and the free Visual Web Developer 2010 Express.  You’ll find with VS 2010 that JavaScript Intellisense loads much faster for large script files and with large libraries, and that it now provides statement completion support for more advanced scenarios compared to previous versions of Visual Studio. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] Improved JavaScript Intellisense Providing Intellisense for a dynamic language like JavaScript is more involved than doing so with a statically typed language like VB or C#.  Correctly inferring the shape and structure of variables, methods, etc is pretty much impossible without pseudo-executing the actual code itself – since JavaScript as a language is flexible enough to dynamically modify and morph these things at runtime.  VS 2010’s JavaScript code editor now has the smarts to perform this type of pseudo-code execution as you type – which is how its intellisense completion is kept accurate and complete.  Below is a simple walkthrough that shows off how rich and flexible it is with the final release. Scenario 1: Basic Type Inference When you declare a variable in JavaScript you do not have to declare its type.  Instead, the type of the variable is based on the value assigned to it.  Because VS 2010 pseudo-executes the code within the editor, it can dynamically infer the type of a variable, and provide the appropriate code intellisense based on the value assigned to a variable. For example, notice below how VS 2010 provides statement completion for a string (because we assigned a string to the “foo” variable): If we later assign a numeric value to “foo” the statement completion (after this assignment) automatically changes to provide intellisense for a number: Scenario 2: Intellisense When Manipulating Browser Objects It is pretty common with JavaScript to manipulate the DOM of a page, as well as work against browser objects available on the client.  Previous versions of Visual Studio would provide JavaScript statement completion against the standard browser objects – but didn’t provide much help with more advanced scenarios (like creating dynamic variables and methods).  VS 2010’s pseudo-execution of code within the editor now allows us to provide rich intellisense for a much broader set of scenarios. For example, below we are using the browser’s window object to create a global variable named “bar”.  Notice how we can now get intellisense (with correct type inference for a string) with VS 2010 when we later try and use it: When we assign the “bar” variable as a number (instead of as a string) the VS 2010 intellisense engine correctly infers its type and modifies statement completion appropriately to be that of a number instead: Scenario 3: Showing Off Because VS 2010 is psudo-executing code within the editor, it is able to handle a bunch of scenarios (both practical and wacky) that you throw at it – and is still able to provide accurate type inference and intellisense. For example, below we are using a for-loop and the browser’s window object to dynamically create and name multiple dynamic variables (bar1, bar2, bar3…bar9).  Notice how the editor’s intellisense engine identifies and provides statement completion for them: Because variables added via the browser’s window object are also global variables – they also now show up in the global variable intellisense drop-down as well: Better yet – type inference is still fully supported.  So if we assign a string to a dynamically named variable we will get type inference for a string.  If we assign a number we’ll get type inference for a number.  Just for fun (and to show off!) we could adjust our for-loop to assign a string for even numbered variables (bar2, bar4, bar6, etc) and assign a number for odd numbered variables (bar1, bar3, bar5, etc): Notice above how we get statement completion for a string for the “bar2” variable.  Notice below how for “bar1” we get statement completion for a number:   This isn’t just a cool pet trick While the above example is a bit contrived, the approach of dynamically creating variables, methods and event handlers on the fly is pretty common with many Javascript libraries.  Many of the more popular libraries use these techniques to keep the size of script library downloads as small as possible.  VS 2010’s support for parsing and pseudo-executing libraries that use these techniques ensures that you get better code Intellisense out of the box when programming against them. Summary Visual Studio 2010 (and the free Visual Web Developer 2010 Express) now provide much richer JavaScript intellisense support.  This support works with pretty much all popular JavaScript libraries.  It should help provide a much better development experience when coding client-side JavaScript and enabling AJAX scenarios within your ASP.NET applications. Hope this helps, Scott P.S. You can read my previous blog post on VS 2008’s JavaScript Intellisense to learn more about our previous JavaScript intellisense (and some of the scenarios it supported).  VS 2010 obviously supports all of the scenarios previously enabled with VS 2008.

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• SQL SERVER – Fundamentals of Columnstore Index

  - by pinaldave

  There are two kind of storage in database. Row Store and Column Store. Row store does exactly as the name suggests – stores rows of data on a page – and column store stores all the data in a column on the same page. These columns are much easier to search – instead of a query searching all the data in an entire row whether the data is relevant or not, column store queries need only to search much lesser number of the columns. This means major increases in search speed and hard drive use. Additionally, the column store indexes are heavily compressed, which translates to even greater memory and faster searches. I am sure this looks very exciting and it does not mean that you convert every single index from row store to column store index. One has to understand the proper places where to use row store or column store indexes. Let us understand in this article what is the difference in Columnstore type of index. Column store indexes are run by Microsoft’s VertiPaq technology. However, all you really need to know is that this method of storing data is columns on a single page is much faster and more efficient. Creating a column store index is very easy, and you don’t have to learn new syntax to create them. You just need to specify the keyword “COLUMNSTORE” and enter the data as you normally would. Keep in mind that once you add a column store to a table, though, you cannot delete, insert or update the data – it is READ ONLY. However, since column store will be mainly used for data warehousing, this should not be a big problem. You can always use partitioning to avoid rebuilding the index. A columnstore index stores each column in a separate set of disk pages, rather than storing multiple rows per page as data traditionally has been stored. The difference between column store and row store approaches is illustrated below: In case of the row store indexes multiple pages will contain multiple rows of the columns spanning across multiple pages. In case of column store indexes multiple pages will contain multiple single columns. This will lead only the columns needed to solve a query will be fetched from disk. Additionally there is good chance that there will be redundant data in a single column which will further help to compress the data, this will have positive effect on buffer hit rate as most of the data will be in memory and due to same it will not need to be retrieved. Let us see small example of how columnstore index improves the performance of the query on a large table. As a first step let us create databaseset which is large enough to show performance impact of columnstore index. The time taken to create sample database may vary on different computer based on the resources. USE AdventureWorks GO -- Create New Table CREATE TABLE [dbo].[MySalesOrderDetail]( [SalesOrderID] [int] NOT NULL, [SalesOrderDetailID] [int] NOT NULL, [CarrierTrackingNumber] [nvarchar](25) NULL, [OrderQty] [smallint] NOT NULL, [ProductID] [int] NOT NULL, [SpecialOfferID] [int] NOT NULL, [UnitPrice] [money] NOT NULL, [UnitPriceDiscount] [money] NOT NULL, [LineTotal] [numeric](38, 6) NOT NULL, [rowguid] [uniqueidentifier] NOT NULL, [ModifiedDate] [datetime] NOT NULL ) ON [PRIMARY] GO -- Create clustered index CREATE CLUSTERED INDEX [CL_MySalesOrderDetail] ON [dbo].[MySalesOrderDetail] ( [SalesOrderDetailID]) GO -- Create Sample Data Table -- WARNING: This Query may run upto 2-10 minutes based on your systems resources INSERT INTO [dbo].[MySalesOrderDetail] SELECT S1.* FROM Sales.SalesOrderDetail S1 GO 100 Now let us do quick performance test. I have kept STATISTICS IO ON for measuring how much IO following queries take. In my test first I will run query which will use regular index. We will note the IO usage of the query. After that we will create columnstore index and will measure the IO of the same. -- Performance Test -- Comparing Regular Index with ColumnStore Index USE AdventureWorks GO SET STATISTICS IO ON GO -- Select Table with regular Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID GO -- Table 'MySalesOrderDetail'. Scan count 1, logical reads 342261, physical reads 0, read-ahead reads 0. -- Create ColumnStore Index CREATE NONCLUSTERED COLUMNSTORE INDEX [IX_MySalesOrderDetail_ColumnStore] ON [MySalesOrderDetail] (UnitPrice, OrderQty, ProductID) GO -- Select Table with Columnstore Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID GO It is very clear from the results that query is performance extremely fast after creating ColumnStore Index. The amount of the pages it has to read to run query is drastically reduced as the column which are needed in the query are stored in the same page and query does not have to go through every single page to read those columns. If we enable execution plan and compare we can see that column store index performance way better than regular index in this case. Let us clean up the database. -- Cleanup DROP INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] GO TRUNCATE TABLE dbo.MySalesOrderDetail GO DROP TABLE dbo.MySalesOrderDetail GO In future posts we will see cases where Columnstore index is not appropriate solution as well few other tricks and tips of the columnstore index. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Auto DOP and Concurrency

  - by jean-pierre.dijcks

  After spending some time in the cloud, I figured it is time to come down to earth and start discussing some of the new Auto DOP features some more. As Database Machines (the v2 machine runs Oracle Database 11.2) are effectively selling like hotcakes, it makes some sense to talk about the new parallel features in more detail. For basic understanding make sure you have read the initial post. The focus there is on Auto DOP and queuing, which is to some extend the focus here. But now I want to discuss the concurrency a little and explain some of the relevant parameters and their impact, specifically in a situation with concurrency on the system. The goal of Auto DOP The idea behind calculating the Automatic Degree of Parallelism is to find the highest possible DOP (ideal DOP) that still scales. In other words, if we were to increase the DOP even more  above a certain DOP we would see a tailing off of the performance curve and the resource cost / performance would become less optimal. Therefore the ideal DOP is the best resource/performance point for that statement. The goal of Queuing On a normal production system we should see statements running concurrently. On a Database Machine we typically see high concurrency rates, so we need to find a way to deal with both high DOP’s and high concurrency. Queuing is intended to make sure we Don’t throttle down a DOP because other statements are running on the system Stay within the physical limits of a system’s processing power Instead of making statements go at a lower DOP we queue them to make sure they will get all the resources they want to run efficiently without trashing the system. The theory – and hopefully – practice is that by giving a statement the optimal DOP the sum of all statements runs faster with queuing than without queuing. Increasing the Number of Potential Parallel Statements To determine how many statements we will consider running in parallel a single parameter should be looked at. That parameter is called PARALLEL_MIN_TIME_THRESHOLD. The default value is set to 10 seconds. So far there is nothing new here…, but do realize that anything serial (e.g. that stays under the threshold) goes straight into processing as is not considered in the rest of this post. Now, if you have a system where you have two groups of queries, serial short running and potentially parallel long running ones, you may want to worry only about the long running ones with this parallel statement threshold. As an example, lets assume the short running stuff runs on average between 1 and 15 seconds in serial (and the business is quite happy with that). The long running stuff is in the realm of 1 – 5 minutes. It might be a good choice to set the threshold to somewhere north of 30 seconds. That way the short running queries all run serial as they do today (if it ain’t broken, don’t fix it) and allows the long running ones to be evaluated for (higher degrees of) parallelism. This makes sense because the longer running ones are (at least in theory) more interesting to unleash a parallel processing model on and the benefits of running these in parallel are much more significant (again, that is mostly the case). Setting a Maximum DOP for a Statement Now that you know how to control how many of your statements are considered to run in parallel, lets talk about the specific degree of any given statement that will be evaluated. As the initial post describes this is controlled by PARALLEL_DEGREE_LIMIT. This parameter controls the degree on the entire cluster and by default it is CPU (meaning it equals Default DOP). For the sake of an example, let’s say our Default DOP is 32. Looking at our 5 minute queries from the previous paragraph, the limit to 32 means that none of the statements that are evaluated for Auto DOP ever runs at more than DOP of 32. Concurrently Running a High DOP A basic assumption about running high DOP statements at high concurrency is that you at some point in time (and this is true on any parallel processing platform!) will run into a resource limitation. And yes, you can then buy more hardware (e.g. expand the Database Machine in Oracle’s case), but that is not the point of this post… The goal is to find a balance between the highest possible DOP for each statement and the number of statements running concurrently, but with an emphasis on running each statement at that highest efficiency DOP. The PARALLEL_SERVER_TARGET parameter is the all important concurrency slider here. Setting this parameter to a higher number means more statements get to run at their maximum parallel degree before queuing kicks in.  PARALLEL_SERVER_TARGET is set per instance (so needs to be set to the same value on all 8 nodes in a full rack Database Machine). Just as a side note, this parameter is set in processes, not in DOP, which equates to 4* Default DOP (2 processes for a DOP, default value is 2 * Default DOP, hence a default of 4 * Default DOP). Let’s say we have PARALLEL_SERVER_TARGET set to 128. With our limit set to 32 (the default) we are able to run 4 statements concurrently at the highest DOP possible on this system before we start queuing. If these 4 statements are running, any next statement will be queued. To run a system at high concurrency the PARALLEL_SERVER_TARGET should be raised from its default to be much closer (start with 60% or so) to PARALLEL_MAX_SERVERS. By using both PARALLEL_SERVER_TARGET and PARALLEL_DEGREE_LIMIT you can control easily how many statements run concurrently at good DOPs without excessive queuing. Because each workload is a little different, it makes sense to plan ahead and look at these parameters and set these based on your requirements.

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• Big Data – Evolution of Big Data – Day 3 of 21

  - by Pinal Dave

  In yesterday’s blog post we answered what is the Big Data. Today we will understand why and how the evolution of Big Data has happened. Though the answer is very simple, I would like to tell it in the form of a history lesson. Data in Flat File In earlier days data was stored in the flat file and there was no structure in the flat file.  If any data has to be retrieved from the flat file it was a project by itself. There was no possibility of retrieving the data efficiently and data integrity has been just a term discussed without any modeling or structure around. Database residing in the flat file had more issues than we would like to discuss in today’s world. It was more like a nightmare when there was any data processing involved in the application. Though, applications developed at that time were also not that advanced the need of the data was always there and there was always need of proper data management. Edgar F Codd and 12 Rules Edgar Frank Codd was a British computer scientist who, while working for IBM, invented the relational model for database management, the theoretical basis for relational databases. He presented 12 rules for the Relational Database and suddenly the chaotic world of the database seems to see discipline in the rules. Relational Database was a promising land for all the unstructured database users. Relational Database brought into the relationship between data as well improved the performance of the data retrieval. Database world had immediately seen a major transformation and every single vendors and database users suddenly started to adopt the relational database models. Relational Database Management Systems Since Edgar F Codd proposed 12 rules for the RBDMS there were many different vendors who started them to build applications and tools to support the relationship between database. This was indeed a learning curve for many of the developer who had never worked before with the modeling of the database. However, as time passed by pretty much everybody accepted the relationship of the database and started to evolve product which performs its best with the boundaries of the RDBMS concepts. This was the best era for the databases and it gave the world extreme experts as well as some of the best products. The Entity Relationship model was also evolved at the same time. In software engineering, an Entity–relationship model (ER model) is a data model for describing a database in an abstract way. Enormous Data Growth Well, everything was going fine with the RDBMS in the database world. As there were no major challenges the adoption of the RDBMS applications and tools was pretty much universal. There was a race at times to make the developer’s life much easier with the RDBMS management tools. Due to the extreme popularity and easy to use system pretty much every data was stored in the RDBMS system. New age applications were built and social media took the world by the storm. Every organizations was feeling pressure to provide the best experience for their users based the data they had with them. While this was all going on at the same time data was growing pretty much every organization and application. Data Warehousing The enormous data growth now presented a big challenge for the organizations who wanted to build intelligent systems based on the data and provide near real time superior user experience to their customers. Various organizations immediately start building data warehousing solutions where the data was stored and processed. The trend of the business intelligence becomes the need of everyday. Data was received from the transaction system and overnight was processed to build intelligent reports from it. Though this is a great solution it has its own set of challenges. The relational database model and data warehousing concepts are all built with keeping traditional relational database modeling in the mind and it still has many challenges when unstructured data was present. Interesting Challenge Every organization had expertise to manage structured data but the world had already changed to unstructured data. There was intelligence in the videos, photos, SMS, text, social media messages and various other data sources. All of these needed to now bring to a single platform and build a uniform system which does what businesses need. The way we do business has also been changed. There was a time when user only got the features what technology supported, however, now users ask for the feature and technology is built to support the same. The need of the real time intelligence from the fast paced data flow is now becoming a necessity. Large amount (Volume) of difference (Variety) of high speed data (Velocity) is the properties of the data. The traditional database system has limits to resolve the challenges this new kind of the data presents. Hence the need of the Big Data Science. We need innovation in how we handle and manage data. We need creative ways to capture data and present to users. Big Data is Reality! Tomorrow In tomorrow’s blog post we will try to answer discuss Basics of Big Data Architecture. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• MVVM Light V4 preview 2 (BL0015) #mvvmlight

  - by Laurent Bugnion

  Over the past few weeks, I have worked hard on a few new features for MVVM Light V4. Here is a second early preview (consider this pre-alpha if you wish). The features are unit-tested, but I am now looking for feedback and there might be bugs! Bug correction: Messenger.CleanupList is now thread safe This was an annoying bug that is now corrected: In some circumstances, an exception could be thrown when the Messenger’s recipients list was cleaned up (i.e. the “dead” instances were removed). The method is called now and then and the exception was thrown apparently at random. In fact it was really a multi-threading issue, which is now corrected. Bug correction: AllowPartiallyTrustedCallers prevents EventToCommand to work This is a particularly annoying regression bug that was introduced in BL0014. In order to allow MVVM Light to work in XBAPs too, I added the AllowPartiallyTrustedCallers attribute to the assemblies. However, we just found out that this causes issues when using EventToCommand. In order to allow EventToCommand to continue working, I reverted to the previous state by removing the AllowPartiallyTrustedCallers attribute for now. I will work with my friends at Microsoft to try and find a solution. Stay tuned. Bug correction: XML documentation file is now generated in Release configuration The XML documentation file was not generated for the Release configuration. This was a simple flag in the project file that I had forgotten to set. This is corrected now. Applying EventToCommand to non-FrameworkElements This feature has been requested in order to be able to execute a command when a Storyboard is completed. I implemented this, but unfortunately found out that EventToCommand can only be added to Storyboards in Silverlight 3 and Silverlight 4, but not in WPF or in Windows Phone 7. This obviously limits the usefulness of this change, but I decided to publish it anyway, because it is pretty damn useful in Silverlight… Why not in WPF? In WPF, Storyboards added to a resource dictionary are frozen. This is a feature of WPF which allows to optimize certain objects for performance: By freezing them, it is a contract where we say “this object will not be modified anymore, so do your perf optimization on them without worrying too much”. Unfortunately, adding a Trigger (such as EventTrigger) to an object in resources does not work if this object is frozen… and unfortunately, there is no way to tell WPF not to freeze the Storyboard in the resources… so there is no way around that (at least none I can see. In Silverlight, objects are not frozen, so an EventTrigger can be added without problems. Why not in WP7? In Windows Phone 7, there is a totally different issue: Adding a Trigger can only be done to a FrameworkElement, which Storyboard is not. Here I think that we might see a change in a future version of the framework, so maybe this small trick will work in the future. Workaround? Since you cannot use the EventToCommand on a Storyboard in WPF and in WP7, the workaround is pretty obvious: Handle the Completed event in the code behind, and call the Command from there on the ViewModel. This object can be obtained by casting the DataContext to the ViewModel type. This means that the View needs to know about the ViewModel, but I never had issues with that anyway. New class: NotifyPropertyChanged Sometimes when you implement a model object (for example Customer), you would like to have it implement INotifyPropertyChanged, but without having all the frills of a ViewModelBase. A new class named NotifyPropertyChanged allows you to do that. This class is a simple implementation of INotifyPropertyChaned (with all the overloads of RaisePropertyChanged that were implemented in BL0014). In fact, ViewModelBase inherits NotifyPropertyChanged. ViewModelBase does not implement IDisposable anymore The IDisposable interface and the Dispose method had been marked obsolete in the ViewModelBase class already in V3. Now they have been removed. Note: By this, I do not mean that IDisposable is a bad interface, or that it shouldn’t be used on viewmodels. In the contrary, I know that this interface is very useful in certain circumstances. However, I think that having it by default on every instance of ViewModelBase was sending a wrong message. This interface has a strong meaning in .NET: After Dispose has been executed, the instance should not be used anymore, and should be ready for garbage collection. What I really wanted to have on ViewModelBase was rather a simple cleanup method, something that can be executed now and then during runtime. This is fulfilled by the ICleanup interface and its Cleanup method. If your ViewModels need IDisposable, you can still use it! You will just have to implement the interface on the class itself, because it is not available on ViewModelBase anymore. What’s next? I have a couple exciting new features implemented already but that need more testing before they go live… Just stay tuned and by MIX11 (12-14 April 2011), we should see at least a major addition to MVVM Light Toolkit, as well as another smaller feature which is pretty cool nonetheless More about this later! Happy Coding Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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• Design a T-shirt for .NET Reflector Pro

  - by Laila

  Win a .NET Reflector Pro license, a box of Red Gate goodies, and a t-shirt printed with your design! Red Gate likes t-shirts. Each of our teams has one. In fact, each individual person has one, numbered according to when they joined the company: Red Gate's 1st, 2nd, and so on right up to Red Gate's 170th, with the slogan "More than just a number". Those t-shirts are important, chiefly because they remind the people wearing them that they are important. But that isn't enough. What really makes us great are the people who choose to use our tools. So we'd like to extend our tradition of t-shirts to include you and put the design of our next shirt entirely in your hands. We'd like you to come up with a witty slogan or create an inventive or simply beautiful t-shirt design for .NET Reflector Pro, our add-in for Visual Studio, which allows you to step into decompiled assemblies whilst debugging in Visual Studio. When you're done, post your masterpiece to Twitter with the hash tag #reflectortees, and @redgate will take a look! We'll pick the best design, and the winner will get a licensed copy of .NET Reflector Pro and a box of Red Gate goodies - not to mention a copy of their t-shirt. The winning design will go into production and be worn and given out at tradeshows, conferences, and user group events across the world, proudly bearing the name of their designer. We'll also pick three runners-up who will receive licenses for .NET Reflector Pro. Red Gate goodie box Interested? If you're up for the challenge, then we've got some resources to get you started. Inside the .zip file you'll find high-quality versions of the following: T-shirt templates: don't forget to design the front and the back! Different versions of the .NET Reflector Pro logo and Red Gate logo. Colour sheets to give you an easy reference to the Red Gate colours, including hex and RGB values. You can create and send us as many designs as you like, and each of them will be considered for the prize. To submit your designs, simply tweet including the competition hash tag, #reflectortees, and a link to somewhere we can see your design: either an image hosting site such as Twitpic, Flickr or Picasa, or a personal blog. You will need to create a Twitter account (which is free), if you don't already have one. You only have three limits: The background colour of the t-shirt should be one of our brand colours (red, light/dark grey or black), though you're welcome to use other colours in the rest of the design. You need to make use of either the .NET Reflector Pro logo OR the Red Gate logo (please keep them as they are) If you include any text or slogan, stick with just one or two colors for it. Apart from that, go wild. Go and do whatever it is you do when you get creative: whether you walk barefoot on the grass with a pencil and paper, sit cross-legged on a pile of cushions with a laptop, or simply close your eyes and float through a mist of ideas, now is your chance. Make sure you enjoy it. We're looking forward to seeing your creations. Terms and conditions 1. The closing date for entries is June 11th, 2010 (4 p.m. UK time). Red Gate Software Ltd reserves the right to extend the competition deadline at its discretion. If there is a revision, the revised date will be published on this blog and the date for announcing the results will be postponed accordingly. 2. The winning designer will be notified on June 14th, 2010 through Twitter. The winner must claim his/her prize by sending us a high-resolution image of their design via email (i.e. Illustrator EPS files or appropriate format, ideally at 300dpi). If the winner does not come forward within 3 days of the announcement, they will forfeit their prize and another winner will be selected from the runners-up. The names of the winner and runners-up will be posted on this blog by June 18th.  3. Entry is completed on the designer posting a link to their entry in a tweet with the correct hash tag, #reflectortees. 4. Red Gate Software needs to hold the rights to using the winning design in order to put the t-shirt into production. We will make sure that this is fine with the winner before we do so, but if you do not want us holding the rights to your design, please do not submit your designs. We reserve the right to slightly alter or adjust any artwork we decide to use (mainly to make it easier to print), but we will make sure we contact the winner for approval first. The winner will also need to allow us the use of his/her name for purposes of promoting your design. 5. Entries must be entirely your own original work and must not breach any copyright or third party rights. Red Gate Software Ltd will not be made partially or fully liable for any non-original work submitted by you. 6. This competition is free: you do not need to buy anything or be an existing customer to enter. 7. This competition is not open to employees of Red Gate Software Ltd, their families, or any other company directly connected with the administration of this promotion.

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• Profit's COLLABORATE 10 Session Selections

  - by Aaron Lazenby

  COLLABORATE 2010 is a mere 11 days away (thanks for the reminder @ocp_advisor). Every year I publish my a list of the sessions I think reflect some of the more interesting people/trends in enterprise IT. I should be at all of these sessions, so drop by for a chat--I'll be the guy tapping out emails on my iPad... Monday, April 19 9:15 a.m. - Keynote: Transforming Customer Value, Delivering Highest Customer Service Location: Keynote Hall I never miss Charles Phillips when he speaks--it's one of the best opportunities to get an update on Oracle product developments and strategy. And there's certainly occasion for an update: this will be Phillips' first big presentation since the Oracle + Sun Strategy Update in late January. Phillips is appearing with Oracle Executive Vice President of Development Thomas Kurian which means there should be some excellent information about how customers are using Oracle's complete software and hardware stack to address enterprise IT challenges. The session should provide some excellent context for the rest of the week's session...don't miss it. 10:45 a.m. - Oracle Fusion Applications: Functional Overview Location: South Seas FI met Basheer Khan at COLLABORATE 08 in Denver and have followed his work ever since. He's a former member of the OAUG Board of Directors, an Oracle ACE, and a charismatic enterprise IT expert. Having worked with the Oracle Usability Advisory Board, Basheer should have some fascinating insights to share about the features and interface of Oracle's Fusine Applications. This session, along with Nadia Bendjedou's "10 Things You Can Do Today to Prepare for the Next Generation Applications" (on Tuesday, April 20 8:00 a.m. in room 3662) should give attendees the update they need about Oracle's next-generation applications.   1:15p.m. - E-Business Suite in the Amazon Cloud Location: South Seas HI did my first full-fledged cloud computing coverage at last year's COLLABORATE show (check out my interview with Oracle's Bill Hodak), where I first learned about Amazon's EC2 offering. I've since talked with several people who have provisioned server space on Amazon's cloud with great results. So I'm looking forward to watching the audience configure an instance of the Oracle E-Business Suite release 12 on the cloud while Chuck Edwards from Blue Gecko drives. This session should take some of the mist and vapor out of the cloud conversation.2:30 p.m. - "Zero Sign-on" to EBS - Enabling 96000 Users to Login to EBS Without User Maintenance Location: South Seas HI'll be sitting tight in South Seas H for the next session on Monday where Doug Pepka, a ten-year veteran of communications giant Comcast, will be walking attendees through a massive single sign-on (SSO) project across the enterprise. I'm working on a story about SSO for the August issue of Profit, so this session has real practical value to me. Plus the proliferation of user account logins--both personal and professional--makes this a critical usability/change management issue for IT leaders planning for successful long-term IT implementations.   Tuesday 8:00 am  - Information Architecture for Men in Kilts Location: SURF AGetting to a 8:00 a.m. presentation is a tall order in Las Vegas, but presenter Billy Cripe will make it worth your effort. Not only is the title of this session great, but the content should appeal to any IT strategist looking to push the limits of Web 2.0 technologies in the enterprise. Cripe is a product management director of Enterprise 2.0 and Enterprise Content Management at Oracle, author of Reshaping Your Business with Web 2.0, and a prolific blogger--he knows how information architecture is critical to and enterprise 2.0 implementation.    10:30a.m. - Oracle Virtualization: From Desktop to Data Center Location: REEF FData center virtualization is still one of the best ways to reduce the cost of running enterprise IT. With the addition of Sun products, Oracle has the industry's most comprehensive virtualization portfolio. I must admit, I'm no expert in this subject. So I'm looking forward to Monica Kumar's presentation so I can get up to speed.   Wednesday 8:00 a.m. - The Art of the Steal Location: Mandalay Bay Ballroom JMany will know Frank Abagnale from Steven Spielberg's 2002 film "Catch Me if You Can." The one-time con man and international fugitive who swindled $2.5 million in forged checks went on to help U.S. federal officials investigate fraud cases. Now the CEO of Abagnale and Associates, he has become an invaluable source to the business world on the subject of fraud and fraud protection. With identity theft and digital fraud still on the rise, this session should be an entertaining, and sobering, education on the threats facing businesses and customers around the world. A great way to start Wednesday.1:00 p.m. - Google Wave: Will it replace e-mail as we know it today? Location: SURF EBy many assessments (my own included), Google Wave is a bit of an open collaboration failure. It may seem like an odd reason for me to be excited about this session, but I'm looking forward to the chance to revisit the technology. Also, this is a great case study in connecting free, available Internet tools to existing enterprise computing environments--an issue that IT strategists must contend with as workers spreads out and choose their own productivity tools.  

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• Autoscaling in a modern world&hellip;. Part 2

  - by Steve Loethen

  When we last left off, we had a web application spinning away in the cloud, and a local console application watching it and reacting to changes in demand.  Reactions that were specified by a set of rules.  Let’s talk about those rules. Constraints.  The first set of rules this application answered to were the constraints. Here is what they looked like: <constraintRules> <rule name="default" enabled="true" rank="1" description="The default constraint rule"> <actions> <range min="1" max="4" target="AutoscalingApplicationRole"/> </actions> </rule> </constraintRules> Pretty basic.  We have one role, the “AutoscalingApplicationRole”, and we have decided to have it live within a range of 1 to 4.  This rule does not adjust, but instead, set’s limits on what other rules can do.  It has a rank, so you can have you can specify other sets of constraints, perhaps based on time or date, to allow for deviations from this set.  But for now, let’s keep it simple.  In the real world, you would probably use the minimum to set a lower end SLA.  A common value might be a 2, to prevent the reactive rules from ever taking you down to 1 role.  The maximum is often used to keep a rule from driving the cost up, setting an upper limit to prevent you waking up one morning and find a bill for hundreds of instances you didn’t expect.  So, here we have the range we want our application to live inside.  This is good for our investigation and testing.  Next, let’s take a look at the reactive rules.  These rules are what you use to react (hence reactive rules) to changing demands on your application.  The HOL has two simple rules.  One that looks at a queue depth, and one that looks at a performance counter that reports cpu utilization.  the XML in the rules file looks like this: <reactiveRules> <rule name="ScaleUp" rank="10" description="Scale Up the web role" enabled="true"> <when> <any> <greaterOrEqual operand="Length_05_holqueue" than="10"/> <greaterOrEqual operand="CPU_05_holwebrole" than="65"/> </any> </when> <actions> <scale target="AutoscalingApplicationRole" by="1"/> </actions> </rule> <rule name="ScaleDown" rank="10" description="Scale down the web role" enabled="true"> <when> <all> <less operand="Length_05_holqueue" than="5"/> <less operand="CPU_05_holwebrole" than="40"/> </all> </when> <actions> <scale target="AutoscalingApplicationRole" by="-1"/> </actions> </rule> </reactiveRules> <operands> <performanceCounter alias="CPU_05_holwebrole" performanceCounterName="\Processor(_Total)\% Processor Time" source="AutoscalingApplicationRole" timespan="00:05:00" aggregate="Average" /> <queueLength alias="Length_05_holqueue" queue="hol-queue" timespan="00:05:00" aggregate="Average"/> </operands> These rules are currently contained in a file called rules.xml, that is in the root of the console application.  The console app, starts up, grabs the rules and starts watching the 2 operands.  When it detects a rule has been satisfied, it performs the desired action.  (here, scale up or down my 1). But I want to host the autoscaler  in the cloud.  For my first trick, I will move the rules (and another file called services.xml) to azure blob storage.  Look for part 3.

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• JQuery and the multiple date selector

  - by David Carter

  Overview I recently needed to build a web page that would allow a user to capture some information and most importantly select multiple dates. This functionality was core to the application and hence had to be easy and quick to do. This is a public facing website so it had to be intuitive and very responsive. On the face of it it didn't seem too hard, I know enough juery to know what it is capable of and I was pretty sure that there would be some plugins that would help speed things along the way. I'm using ASP.Net MVC for this project as I really like the control that it gives you over the generated html and javascript. After years of Web Forms development it makes me feel like a web developer again and puts a smile on my face, that can only be a good thing!   The Calendar The first item that I needed on this page was a calender and I wanted the ability to: have the calendar be always visible select/deselect multiple dates at the same time bind to the select/deselect event so that I could update a seperate listing of the selected dates allow the user to move to another month and still have the calender remember any dates in the previous month I was hoping that there was a jQuery plugin that would meet my requirements and luckily there was! The jQuery datepicker does everything I want and there is quite a bit of documentation on how to use it. It makes use of a javascript date library date.js which I had not come across before but has a number of very useful date utilities that I have used elsewhere in the project. As you can see from the image there still needs to be some styling done! But there will be plenty of time for that later. The calendar clearly shows which dates the user has selected in red and i also make use of an unordered list to show the the selected dates so the user can always clearly see what has been selected even if they move to another month on the calendar. The javascript code that is responsible for listening to events on the calendar and synchronising the list look as follows: <script type="text/javascript">     $(function () {         $('.datepicker').datePicker({ inline: true, selectMultiple: true })         .bind(             'dateSelected',             function (e, selectedDate, $td, state) {                                 var dateInMillisecs = selectedDate.valueOf();                 if (state) { //adding a date                     var newDate = new Date(selectedDate);                     //insert the new item into the correct place in the list                     var listitems = $('#dateList').children('li').get();                     var liToAdd = "<li id='" + dateInMillisecs + "' >" + newDate.toString('ddd dd MMM yyyy') + "</li>";                     var targetIndex = -1;                     for (var i = 0; i < listitems.length; i++) {                         if (dateInMillisecs <= listitems[i].id) {                             targetIndex = i;                             break;                         }                     }                     if (targetIndex < 0) {                         $('#dateList').append(liToAdd);                     }                     else {                         $($('#dateList').children("li")[targetIndex]).before(liToAdd);                     }                 }                 else {//removing a date                     $('ul #' + dateInMillisecs).remove();                 }             }         )     }); When a date is selected on the calendar a function is called with a number of parameters passed to it. The ones I am particularly interested in are selectedDate and state. State tells me whether the user has selected or deselected the date passed in the selectedDate parameter. The <ul> that I am using to show the date has an id of dateList and this is what I will be adding and removing <li> items from. To make things a little more logical for the user I decided that the date should be sorted in chronological order, this means that each time a new date is selected it need to be placed in the correct position in the list. One way to do this would be just to append a new <li> to the list and then sort the whole list. However the approach I took was to get an array of all the items in the list var listitems = ('#dateList').children('li').get(); and then check the value of each item in the array against my new date and as soon as I found the case where the new date was less than the current item remember that position in the list as this is where I would insert it later. To make this work easily I decided to store a numeric representation of each date in the list in the id attribute of each <li> element. Fortunately javascript natively stores dates as the number of milliseconds since 1 Jan 1970. var dateInMillisecs = selectedDate.valueOf(); Please note that this is the value of the date in UTC! I always like to store dates in UTC as I learnt a long time ago that it saves a lot of refactoring at a later date... When I convert the dates back to their original back on the server I will need the UTC offset that was used when calculating the dates, this and how to actually serialise the dates and get them posted back will be the subject of another post.

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• The Unspoken - The Why of GC Ergonomics

  - by jonthecollector

  Do you use GC ergonomics, -XX:+UseAdaptiveSizePolicy, with the UseParallelGC collector? The jist of GC ergonomics for that collector is that it tries to grow or shrink the heap to meet a specified goal. The goals that you can choose are maximum pause time and/or throughput. Don't get too excited there. I'm speaking about UseParallelGC (the throughput collector) so there are definite limits to what pause goals can be achieved. When you say out loud "I don't care about pause times, give me the best throughput I can get" and then say to yourself "Well, maybe 10 seconds really is too long", then think about a pause time goal. By default there is no pause time goal and the throughput goal is high (98% of the time doing application work and 2% of the time doing GC work). You can get more details on this in my very first blog. GC ergonomics The UseG1GC has its own version of GC ergonomics, but I'll be talking only about the UseParallelGC version. If you use this option and wanted to know what it (GC ergonomics) was thinking, try -XX:AdaptiveSizePolicyOutputInterval=1 This will print out information every i-th GC (above i is 1) about what the GC ergonomics to trying to do. For example, UseAdaptiveSizePolicy actions to meet *** throughput goal *** GC overhead (%) Young generation: 16.10 (attempted to grow) Tenured generation: 4.67 (attempted to grow) Tenuring threshold: (attempted to decrease to balance GC costs) = 1 GC ergonomics tries to meet (in order) Pause time goal Throughput goal Minimum footprint The first line says that it's trying to meet the throughput goal. UseAdaptiveSizePolicy actions to meet *** throughput goal *** This run has the default pause time goal (i.e., no pause time goal) so it is trying to reach a 98% throughput. The lines Young generation: 16.10 (attempted to grow) Tenured generation: 4.67 (attempted to grow) say that we're currently spending about 16% of the time doing young GC's and about 5% of the time doing full GC's. These percentages are a decaying, weighted average (earlier contributions to the average are given less weight). The source code is available as part of the OpenJDK so you can take a look at it if you want the exact definition. GC ergonomics is trying to increase the throughput by growing the heap (so says the "attempted to grow"). The last line Tenuring threshold: (attempted to decrease to balance GC costs) = 1 says that the ergonomics is trying to balance the GC times between young GC's and full GC's by decreasing the tenuring threshold. During a young collection the younger objects are copied to the survivor spaces while the older objects are copied to the tenured generation. Younger and older are defined by the tenuring threshold. If the tenuring threshold hold is 4, an object that has survived fewer than 4 young collections (and has remained in the young generation by being copied to the part of the young generation called a survivor space) it is younger and copied again to a survivor space. If it has survived 4 or more young collections, it is older and gets copied to the tenured generation. A lower tenuring threshold moves objects more eagerly to the tenured generation and, conversely a higher tenuring threshold keeps copying objects between survivor spaces longer. The tenuring threshold varies dynamically with the UseParallelGC collector. That is different than our other collectors which have a static tenuring threshold. GC ergonomics tries to balance the amount of work done by the young GC's and the full GC's by varying the tenuring threshold. Want more work done in the young GC's? Keep objects longer in the survivor spaces by increasing the tenuring threshold. This is an example of the output when GC ergonomics is trying to achieve a pause time goal UseAdaptiveSizePolicy actions to meet *** pause time goal *** GC overhead (%) Young generation: 20.74 (no change) Tenured generation: 31.70 (attempted to shrink) The pause goal was set at 50 millisecs and the last GC was 0.415: [Full GC (Ergonomics) [PSYoungGen: 2048K-0K(26624K)] [ParOldGen: 26095K-9711K(28992K)] 28143K-9711K(55616K), [Metaspace: 1719K-1719K(2473K/6528K)], 0.0758940 secs] [Times: user=0.28 sys=0.00, real=0.08 secs] The full collection took about 76 millisecs so GC ergonomics wants to shrink the tenured generation to reduce that pause time. The previous young GC was 0.346: [GC (Allocation Failure) [PSYoungGen: 26624K-2048K(26624K)] 40547K-22223K(56768K), 0.0136501 secs] [Times: user=0.06 sys=0.00, real=0.02 secs] so the pause time there was about 14 millisecs so no changes are needed. If trying to meet a pause time goal, the generations are typically shrunk. With a pause time goal in play, watch the GC overhead numbers and you will usually see the cost of setting a pause time goal (i.e., throughput goes down). If the pause goal is too low, you won't achieve your pause time goal and you will spend all your time doing GC. GC ergonomics is meant to be simple because it is meant to be used by anyone. It was not meant to be mysterious and so this output was added. If you don't like what GC ergonomics is doing, you can turn it off with -XX:-UseAdaptiveSizePolicy, but be pre-warned that you have to manage the size of the generations explicitly. If UseAdaptiveSizePolicy is turned off, the heap does not grow. The size of the heap (and the generations) at the start of execution is always the size of the heap. I don't like that and tried to fix it once (with some help from an OpenJDK contributor) but it unfortunately never made it out the door. I still have hope though. Just a side note. With the default throughput goal of 98% the heap often grows to it's maximum value and stays there. Definitely reduce the throughput goal if footprint is important. Start with -XX:GCTimeRatio=4 for a more modest throughput goal (%20 of the time spent in GC). A higher value means a smaller amount of time in GC (as the throughput goal).

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• How do I consistently re-size my game window and elements?

  - by Milo

  In my 2D game, I have a flow layout. Inside the flow layout are tables. I have a slider that lets the user make the tables larger or smaller. This makes the background larger or smaller too. Everything should scale proportionally which means the background should stay at the same position when I make things larger, and it almost does. When the scrollbar is at 0, it does exactly this. As the scrollbar gets further down problems arise. I'll toggle the slider maybe 3 times and on the fourth time, the background jumps a little lower on the Y axis. In order to be efficient, I only start rendering the background near the parent of the flow layout. Here it is: void LobbyTableManager::renderBG( GraphicsContext* g, agui::Rectangle& absRect, agui::Rectangle& childRect ) { int cx, cy, cw, ch; g->getClippingRect(cx,cy,cw,ch); g->setClippingRect(absRect.getX(),absRect.getY(),absRect.getWidth(),absRect.getHeight()); float scale = 0.35f; int w = m_bgSprite->getWidth() * getTableScale() * scale; int h = m_bgSprite->getHeight() * getTableScale() * scale; int numX = ceil(absRect.getWidth() / (float)w) + 2; int numY = ceil(absRect.getHeight() / (float)h) + 2; float offsetX = m_activeTables[0]->getLocation().getX() - w; float offsetY = m_activeTables[0]->getLocation().getY() - h; int startY = childRect.getY(); if(moo) { std::cout << "S=" << startY << ","; } int numAttempts = 0; while(startY + h < absRect.getY() && numAttempts < 1000) { startY += h; if(moo) { std::cout << startY << ","; } numAttempts++; } if(moo) { std::cout << "\n"; moo = false; } g->holdDrawing(); for(int i = 0; i < numX; ++i) { for(int j = 0; j < numY; ++j) { g->drawScaledSprite(m_bgSprite,0,0,m_bgSprite->getWidth(),m_bgSprite->getHeight(), absRect.getX() + (i * w) + (offsetX),absRect.getY() + (j * h) + startY,w,h,0); } } g->unholdDrawing(); g->setClippingRect(cx,cy,cw,ch); } The numeric problem seems to be in the value of startY. I outputted startY figuring out its value: As you can see here, this is me only zooming in, pay attention to the final number before the next s=. You'll notice that, what should happen is, the numbers should be linear, ex: -40, -38, -36, -34, -32, -30, etc. As you'll notice, the start numbers linearly correlate ex: 62k, 64k, 66k, 68k, 70k etc.. but the end result is wrong every third or 4th time. Here is most of the resize code: void LobbyTableManager::setTableScale( float scale ) { scale += 0.3f; scale *= 2.0f; agui::Gui* gotGui = getGui(); float scrollRel = m_vScroll->getRelativeValue(); setScale(scale); rescaleTables(); resizeFlow(); if(gotGui) { gotGui->toggleWidgetLocationChanged(false); } updateScrollBars(); float newVal = scrollRel * m_vScroll->getMaxValue(); if((int)(newVal + 0.5f) > (int)newVal) { newVal++; } m_vScroll->setValue(newVal); static int x = 0; x++; moo = true; //std::cout << m_vScroll->getValue() << std::endl; if(gotGui) { gotGui->toggleWidgetLocationChanged(true); } if(gotGui) { gotGui->_widgetLocationChanged(); } } void LobbyTableManager::valueChanged( agui::VScrollBar* source,int val ) { if(getGui()) { getGui()->toggleWidgetLocationChanged(false); } m_flow->setLocation(0,-val); if(getGui()) { getGui()->toggleWidgetLocationChanged(true); getGui()->_widgetLocationChanged(); } }

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• Amanda Todd&ndash;What Parents Can Learn From Her Story

  - by D'Arcy Lussier

  Amanda Todd was a bullied teenager who committed suicide this week. Her story has become headline news due in part to her You Tube video she posted telling her story:   The story is heartbreaking for so many reasons, but I wanted to talk about what we as parents can learn from this. Being the dad to two girls, one that’s 10, I’m very aware of the dangers that the internet holds. When I saw her story, one thing jumped out at me – unmonitored internet access at an early age. My daughter (then 9) came home from a friends place once and asked if she could be in a YouTube video with her friend. Apparently this friend was allowed to do whatever she wanted on the internet, including posting goofy videos. This set off warning bells and we ensured our daughter realized the dangers and that she was not to ever post videos of herself. In looking at Amanda’s story, the access to unmonitored internet time along with just being a young girl and being flattered by an online predator were the key events that ultimately led to her suicide. Yes, the reaction of her classmates and “friends” was horrible as well, I’m not diluting that. But our youth don’t fully understand yet that what they do on the internet today will follow them potentially forever. And the people they meet online aren’t necessarily who they claim to be. So what can we as parents learn from Amanda’s story? Parents Shouldn’t Feel Bad About Being Internet Police Our job as parents is in part to protect our kids and keep them safe, even if they don’t like our measures. This includes monitoring, supervising, and restricting their internet activities. In our house we have a family computer in the living room that the kids can watch videos and surf the web. It’s in plain view of everyone, so you can’t hide what you’re looking at. If our daughter goes to a friend’s place, we ask about what they did and what they played. If the computer comes up, we ask about what they did on it. Luckily our daughter is very up front and honest in telling us things, so we have very open discussions. Parents Need to Be Honest About the Dangers of the Internet I’m sure every generation says that “kids grow up so fast these days”, but in our case the internet really does push our kids to be exposed to things they otherwise wouldn’t experience. One wrong word in a Google search, a click of a link in a spam email, or just general curiosity can expose a child to things they aren’t ready for or should never be exposed to (and I’m not just talking about adult material – have you seen some of the graphic pictures from war zones posted on news sites recently?). Our stance as parents has been to be open about discussing the dangers with our kids before they encounter any content – be proactive instead of reactionary. Part of this is alerting them to the monsters that lurk on the internet as well. As kids explore the world wide web, they’re eventually going to encounter some chat room or some Facebook friend invite or other personal connection with someone. More than ever kids need to be educated on the dangers of engaging with people online and sharing personal information. You can think of it as an evolved discussion that our parents had with us about using the phone: “Don’t say ‘I’m home alone’, don’t say when mom or dad get home, don’t tell them any information, etc.” Parents Need to Talk Self Worth at Home Katie makes the point better than I ever could (one bad word towards the end): Our children need to understand their value beyond what the latest issue of TigerBeat says, or the media who continues flaunting physical attributes over intelligence and character, or a society that puts focus on status and wealth. They also have to realize that just because someone pays you a compliment, that doesn’t mean you should ignore personal boundaries and limits. What does this have to do with the internet? Well, in days past if you wanted to be social you had to go out somewhere. Now you can video chat with any number of people from the comfort of wherever your laptop happens to be – and not just text but full HD video with sound! While innocent children head online in the hopes of meeting cool people, predators with bad intentions are heading online too. As much as we try to monitor their online activity and be honest about the dangers of the internet, the human side of our kids isn’t something we can control. But we can try to influence them to see themselves as not needing to search out the acceptance of complete strangers online. Way easier said than done, but ensuring self-worth is something discussed, encouraged, and celebrated is a step in the right direction. Parental Wake Up Call This post is not a critique of Amanda’s parents. The reality is that cyber bullying/abuse is happening every day, and there are millions of parents that have no clue its happening to their children. Amanda’s story is a wake up call that our children’s online activities may be putting them in danger. My heart goes out to the parents of this girl. As a father of daughters, I can’t imagine what I would do if I found my daughter having to hide in a ditch to avoid a mob or call 911 to report my daughter had attempted suicide by drinking bleach or deal with a child turning to drugs/alcohol/cutting to cope. It would be horrendous if we as parents didn’t re-evaluate our family internet policies in light of this event. And in the end, Amanda’s video was meant to bring attention to her plight and encourage others going through the same thing. We may not be kids, but we can still honour her memory by helping safeguard our children.

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• MSSQL: Copying data from one database to another

  - by DigiMortal

  I have database that has data imported from another server using import and export wizard of SQL Server Management Studio. There is also empty database with same tables but it also has primary keys, foreign keys and indexes. How to get data from first database to another? Here is the description of my crusade. And believe me – it is not nice one. Bugs in import and export wizard There is some awful bugs in import and export wizard that makes data imports and exports possible only on very limited manner: wizard is not able to analyze foreign keys, wizard wants to create tables always, whatever you say in settings. The result is faulty and useless package. Now let’s go step by step and make things work in our scenario. Database There are two databases. Let’s name them like this: PLAIN – contains data imported from remote server (no indexes, no keys, no nothing, just plain dumb data) CORRECT – empty database with same structure as remote database (indexes, keys and everything else but no data) Our goal is to get data from PLAIN to CORRECT. 1. Create import and export package In this point we will create faulty SSIS package using SQL Server Management Studio. Run import and export wizard and let it create SSIS package that reads data from CORRECT and writes it to, let’s say, CORRECT-2. Make sure you enable identity insert. Make sure there are no views selected. Make sure you don’t let package to create tables (you can miss this step because it wants to create tables anyway). Save package to SSIS. 2. Modify import and export package Now let’s clean up the package and remove all faulty crap. Connect SQL Server Management Studio to SSIS instance. Select the package you just saved and export it to your hard disc. Run Business Intelligence Studio. Create new SSIS project (DON’T MISS THIS STEP). Add package from disc as existing item to project and open it. Move to Control Flow page do one of following: Remove all preparation SQL-tasks and connect Data Flow tasks. Modify all preparation SQL-tasks so the existence of tables is checked before table is created (yes, you have to do it manually). Add new Execute-SQL task as first task in control flow: Open task properties. Assign destination connection as connection to use. Insert the following SQL as command:   EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' GO   EXEC sp_MSForEachTable 'DELETE FROM ?' GO   Save task. Add new Execute-SQL task as last task in control flow: Open task properties. Assign destination connection as connection to use. Insert the following SQL as command:   EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL' GO   Save task Now connect first Execute-SQL task with first Data Flow task and last Data Flow task with second Execute-SQL task. Now move to Package Explorer tab and change connections under Connection Managers folder. Make source connection to use database PLAIN. Make destination connection to use database CORRECT. Save package and rebuilt the project. Update package using SQL Server Management Studio. Some hints: Make sure you take the package from solution folder because it is saved there now. Don’t overwrite existing package. Use numeric suffix and let Management Studio to create a new version of package. Now you are done with your package. Run it to test it and clean out all the errors you find. TRUNCATE vs DELETE You can see that I used DELETE FROM instead of TRUNCATE. Why? Because TRUNCATE has some nasty limits (taken from MSDN): “You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint; instead, use DELETE statement without a WHERE clause. Because TRUNCATE TABLE is not logged, it cannot activate a trigger. TRUNCATE TABLE may not be used on tables participating in an indexed view.” As I am not sure what tables you have and how they are used I provided here the solution that should work for all scenarios. If you need better performance then in some cases you can use TRUNCATE table instead of DELETE. Conclusion My conclusion is bitter this time although I am very positive guy. It is A.D. 2010 and still we have to write stupid hacks for simple things. Simple tools that existed before are long gone and we have to live mysterious bloatware that is our only choice when using default tools. If you take a look at the length of this posting and the count of steps I had to do for one easy thing you should treat it as a signal that something has went wrong in last years. Although I got my job done I would be still more happy if out of box tools are more intelligent one day. References T-SQL Trick for Deleting All Data in Your Database (Mauro Cardarelli) TRUNCATE TABLE (MSDN Library) Error Handling in SQL 2000 – a Background (Erland Sommarskog) Disable/Enable Foreign Key and Check constraints in SQL Server (Decipher)

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• Why would GLCapabilities.setHardwareAccelerated(true/false) have no effect on performance?

  - by Luke

  I've got a JOGL application in which I am rendering 1 million textures (all the same texture) and 1 million lines between those textures. Basically it's a ball-and-stick graph. I am storing the vertices in a vertex array on the card and referencing them via index arrays, which are also stored on the card. Each pass through the draw loop I am basically doing this: gl.glBindBuffer(GL.GL_ARRAY_BUFFER, <buffer id>); gl.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, <buffer id>); gl.glDrawElements(GL.GL_POINTS, <size>, GL.GL_UNSIGNED_INT, 0); gl.glBindBuffer(GL.GL_ARRAY_BUFFER, <buffer id>); gl.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, <buffer id>); gl.glDrawElements(GL.GL_LINES, <size>, GL.GL_UNSIGNED_INT, 0); I noticed that the JOGL library is pegging one of my CPU cores. Every frame, the run method internal to the library is taking quite long. I'm not sure why this is happening since I have called setHardwareAccelerated(true) on the GLCapabilities used to create my canvas. What's more interesting is that I changed it to setHardwareAccelerated(false) and there was no impact on the performance at all. Is it possible that my code is not using hardware rendering even when it is set to true? Is there any way to check? EDIT: As suggested, I have tested breaking my calls up into smaller chunks. I have tried using glDrawRangeElements and respecting the limits that it requests. All of these simply resulted in the same pegged CPU usage and worse framerates. I have also narrowed the problem down to a simpler example where I just render 4 million textures (no lines). The draw loop then just doing this: gl.glEnableClientState(GL.GL_VERTEX_ARRAY); gl.glEnableClientState(GL.GL_INDEX_ARRAY); gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT); gl.glMatrixMode(GL.GL_MODELVIEW); gl.glLoadIdentity(); <... Camera and transform related code ...> gl.glEnableVertexAttribArray(0); gl.glEnable(GL.GL_TEXTURE_2D); gl.glAlphaFunc(GL.GL_GREATER, ALPHA_TEST_LIMIT); gl.glEnable(GL.GL_ALPHA_TEST); <... Bind texture ...> gl.glBindBuffer(GL.GL_ARRAY_BUFFER, <buffer id>); gl.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, <buffer id>); gl.glDrawElements(GL.GL_POINTS, <size>, GL.GL_UNSIGNED_INT, 0); gl.glDisable(GL.GL_TEXTURE_2D); gl.glDisable(GL.GL_ALPHA_TEST); gl.glDisableVertexAttribArray(0); gl.glFlush(); Where the first buffer contains 12 million floats (the x,y,z coords of the 4 million textures) and the second (element) buffer contains 4 million integers. In this simple example it is simply the integers 0 through 3999999. I really want to know what is being done in software that is pegging my CPU, and how I can make it stop (if I can). My buffers are generated by the following code: gl.glBindBuffer(GL.GL_ARRAY_BUFFER, <buffer id>); gl.glBufferData(GL.GL_ARRAY_BUFFER, <size> * BufferUtil.SIZEOF_FLOAT, <buffer>, GL.GL_STATIC_DRAW); gl.glVertexAttribPointer(0, 3, GL.GL_FLOAT, false, 0, 0); and: gl.glBindBuffer(GL.GL_ELEMENT_ARRAY_BUFFER, <buffer id>); gl.glBufferData(GL.GL_ELEMENT_ARRAY_BUFFER, <size> * BufferUtil.SIZEOF_INT, <buffer>, GL.GL_STATIC_DRAW); ADDITIONAL INFO: Here is my initialization code: gl.setSwapInterval(1); //Also tried 0 gl.glShadeModel(GL.GL_SMOOTH); gl.glClearDepth(1.0f); gl.glEnable(GL.GL_DEPTH_TEST); gl.glDepthFunc(GL.GL_LESS); gl.glHint(GL.GL_PERSPECTIVE_CORRECTION_HINT, GL.GL_FASTEST); gl.glPointParameterfv(GL.GL_POINT_DISTANCE_ATTENUATION, POINT_DISTANCE_ATTENUATION, 0); gl.glPointParameterfv(GL.GL_POINT_SIZE_MIN, MIN_POINT_SIZE, 0); gl.glPointParameterfv(GL.GL_POINT_SIZE_MAX, MAX_POINT_SIZE, 0); gl.glPointSize(POINT_SIZE); gl.glTexEnvf(GL.GL_POINT_SPRITE, GL.GL_COORD_REPLACE, GL.GL_TRUE); gl.glEnable(GL.GL_POINT_SPRITE); gl.glClearColor(clearColor.getX(), clearColor.getY(), clearColor.getZ(), 0.0f); Also, I'm not sure if this helps or not, but when I drag the entire graph off the screen, the FPS shoots back up and the CPU usage falls to 0%. This seems obvious and intuitive to me, but I thought that might give a hint to someone else.

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• C#/.NET Little Wonders: Static Char Methods

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Often times in our code we deal with the bigger classes and types in the BCL, and occasionally forgot that there are some nice methods on the primitive types as well.  Today we will discuss some of the handy static methods that exist on the char (the C# alias of System.Char) type. The Background I was examining a piece of code this week where I saw the following: 1: // need to get the 5th (offset 4) character in upper case 2: var type = symbol.Substring(4, 1).ToUpper(); 3:  4: // test to see if the type is P 5: if (type == "P") 6: { 7: // ... do something with P type... 8: } Is there really any error in this code?  No, but it still struck me wrong because it is allocating two very short-lived throw-away strings, just to store and manipulate a single char: The call to Substring() generates a new string of length 1 The call to ToUpper() generates a new upper-case version of the string from Step 1. In my mind this is similar to using ToUpper() to do a case-insensitive compare: it isn’t wrong, it’s just much heavier than it needs to be (for more info on case-insensitive compares, see #2 in 5 More Little Wonders). One of my favorite books is the C++ Coding Standards: 101 Rules, Guidelines, and Best Practices by Sutter and Alexandrescu.  True, it’s about C++ standards, but there’s also some great general programming advice in there, including two rules I love:         8. Don’t Optimize Prematurely         9. Don’t Pessimize Prematurely We all know what #8 means: don’t optimize when there is no immediate need, especially at the expense of readability and maintainability.  I firmly believe this and in the axiom: it’s easier to make correct code fast than to make fast code correct.  Optimizing code to the point that it becomes difficult to maintain often gains little and often gives you little bang for the buck. But what about #9?  Well, for that they state: “All other things being equal, notably code complexity and readability, certain efficient design patterns and coding idioms should just flow naturally from your fingertips and are no harder to write then the pessimized alternatives. This is not premature optimization; it is avoiding gratuitous pessimization.” Or, if I may paraphrase: “where it doesn’t increase the code complexity and readability, prefer the more efficient option”. The example code above was one of those times I feel where we are violating a tacit C# coding idiom: avoid creating unnecessary temporary strings.  The code creates temporary strings to hold one char, which is just unnecessary.  I think the original coder thought he had to do this because ToUpper() is an instance method on string but not on char.  What he didn’t know, however, is that ToUpper() does exist on char, it’s just a static method instead (though you could write an extension method to make it look instance-ish). This leads me (in a long-winded way) to my Little Wonders for the day… Static Methods of System.Char So let’s look at some of these handy, and often overlooked, static methods on the char type: IsDigit(), IsLetter(), IsLetterOrDigit(), IsPunctuation(), IsWhiteSpace() Methods to tell you whether a char (or position in a string) belongs to a category of characters. IsLower(), IsUpper() Methods that check if a char (or position in a string) is lower or upper case ToLower(), ToUpper() Methods that convert a single char to the lower or upper equivalent. For example, if you wanted to see if a string contained any lower case characters, you could do the following: 1: if (symbol.Any(c => char.IsLower(c))) 2: { 3: // ... 4: } Which, incidentally, we could use a method group to shorten the expression to: 1: if (symbol.Any(char.IsLower)) 2: { 3: // ... 4: } Or, if you wanted to verify that all of the characters in a string are digits: 1: if (symbol.All(char.IsDigit)) 2: { 3: // ... 4: } Also, for the IsXxx() methods, there are overloads that take either a char, or a string and an index, this means that these two calls are logically identical: 1: // check given a character 2: if (char.IsUpper(symbol[0])) { ... } 3:  4: // check given a string and index 5: if (char.IsUpper(symbol, 0)) { ... } Obviously, if you just have a char, then you’d just use the first form.  But if you have a string you can use either form equally well. As a side note, care should be taken when examining all the available static methods on the System.Char type, as some seem to be redundant but actually have very different purposes.  For example, there are IsDigit() and IsNumeric() methods, which sound the same on the surface, but give you different results. IsDigit() returns true if it is a base-10 digit character (‘0’, ‘1’, … ‘9’) where IsNumeric() returns true if it’s any numeric character including the characters for ½, ¼, etc. Summary To come full circle back to our opening example, I would have preferred the code be written like this: 1: // grab 5th char and take upper case version of it 2: var type = char.ToUpper(symbol[4]); 3:  4: if (type == 'P') 5: { 6: // ... do something with P type... 7: } Not only is it just as readable (if not more so), but it performs over 3x faster on my machine:    1,000,000 iterations of char method took: 30 ms, 0.000050 ms/item.    1,000,000 iterations of string method took: 101 ms, 0.000101 ms/item. It’s not only immediately faster because we don’t allocate temporary strings, but as an added bonus there less garbage to collect later as well.  To me this qualifies as a case where we are using a common C# performance idiom (don’t create unnecessary temporary strings) to make our code better. Technorati Tags: C#,CSharp,.NET,Little Wonders,char,string

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• The Joy Of Hex

  - by Jim Giercyk

  While working on a mainframe integration project, it occurred to me that some basic computer concepts are slipping into obscurity. For example, just about anyone can tell you that a 64-bit processor is faster than a 32-bit processer. A grade school child could tell you that a computer “speaks” in ‘1’s and ‘0’s. Some people can even tell you that there are 8 bits in a byte. However, I have found that even the most seasoned developers often can’t explain the theory behind those statements. That is not a knock on programmers; in the age of IntelliSense, what reason do we have to work with data at the bit level? Many computer theory classes treat bit-level programming as a thing of the past, no longer necessary now that storage space is plentiful. The trouble with that mindset is that the world is full of legacy systems that run programs written in the 1970’s.  Today our jobs require us to extract data from those systems, regardless of the format, and that often involves low-level programming. Because it seems knowledge of the low-level concepts is waning in recent times, I thought a review would be in order.       CHARACTER: See Spot Run HEX: 53 65 65 20 53 70 6F 74 20 52 75 6E DECIMAL: 83 101 101 32 83 112 111 116 32 82 117 110 BINARY: 01010011 01100101 01100101 00100000 01010011 01110000 01101111 01110100 00100000 01010010 01110101 01101110 In this example, I have broken down the words “See Spot Run” to a level computers can understand – machine language.     CHARACTER:  The character level is what is rendered by the computer.  A “Character Set” or “Code Page” contains 256 characters, both printable and unprintable.  Each character represents 1 BYTE of data.  For example, the character string “See Spot Run” is 12 Bytes long, exclusive of the quotation marks.  Remember, a SPACE is an unprintable character, but it still requires a byte.  In the example I have used the default Windows character set, ASCII, which you can see here:  http://www.asciitable.com/ HEX:  Hex is short for hexadecimal, or Base 16.  Humans are comfortable thinking in base ten, perhaps because they have 10 fingers and 10 toes; fingers and toes are called digits, so it’s not much of a stretch.  Computers think in Base 16, with numeric values ranging from zero to fifteen, or 0 – F.  Each decimal place has a possible 16 values as opposed to a possible 10 values in base 10.  Therefore, the number 10 in Hex is equal to the number 16 in Decimal.  DECIMAL:  The Decimal conversion is strictly for us humans to use for calculations and conversions.  It is much easier for us humans to calculate that [30 – 10 = 20] in decimal than it is for us to calculate [1E – A = 14] in Hex.  In the old days, an error in a program could be found by determining the displacement from the entry point of a module.  Since those values were dumped from the computers head, they were in hex. A programmer needed to convert them to decimal, do the equation and convert back to hex.  This gets into relative and absolute addressing, a topic for another day.  BINARY:  Binary, or machine code, is where any value can be expressed in 1s and 0s.  It is really Base 2, because each decimal place can have a possibility of only 2 characters, a 1 or a 0.  In Binary, the number 10 is equal to the number 2 in decimal. Why only 1s and 0s?  Very simply, computers are made up of lots and lots of transistors which at any given moment can be ON ( 1 ) or OFF ( 0 ).  Each transistor is a bit, and the order that the transistors fire (or not fire) is what distinguishes one value from  another in the computers head (or CPU).  Consider 32 bit vs 64 bit processing…..a 64 bit processor has the capability to read 64 transistors at a time.  A 32 bit processor can only read half as many at a time, so in theory the 64 bit processor should be much faster.  There are many more factors involved in CPU performance, but that is the fundamental difference.    DECIMAL HEX BINARY 0 0 0000 1 1 0001 2 2 0010 3 3 0011 4 4 0100 5 5 0101 6 6 0110 7 7 0111 8 8 1000 9 9 1001 10 A 1010 11 B 1011 12 C 1100 13 D 1101 14 E 1110 15 F 1111   Remember that each character is a BYTE, there are 2 HEX characters in a byte (called nibbles) and 8 BITS in a byte.  I hope you enjoyed reading about the theory of data processing.  This is just a high-level explanation, and there is much more to be learned.  It is safe to say that, no matter how advanced our programming languages and visual studios become, they are nothing more than a way to interpret bits and bytes.  There is nothing like the joy of hex to get the mind racing.

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• Application Composer: Exposing Your Customizations in BI Analytics and Reporting

  - by Richard Bingham

  Introduction This article explains in simple terms how to ensure the customizations and extensions you have made to your Fusion Applications are available for use in reporting and analytics. It also includes four embedded demo videos from our YouTube channel (if they don't appear check the browser address bar for a blocking shield icon). If you are new to Business Intelligence consider first reviewing our getting started article, and you can read more about the topic of custom subject areas in the documentation book Extending Sales. There are essentially four sections to this post. First we look at how custom fields added to standard objects are made available for reporting. Secondly we look at creating custom subject areas on the standard objects. Next we consider reporting on custom objects, starting with simple standalone objects, then child custom objects, and finally custom objects with relationships. Finally this article reviews how flexfields are exposed for reporting. Whilst this article applies to both Cloud/SaaS and on-premises deployments, if you are an on-premises developer then you can also use the BI Administration Tool to customize your BI metadata repository (the RPD) and create new subject areas. Whilst this is not covered here you can read more in Chapter 8 of the Extensibility Guide for Developers. Custom Fields on Standard Objects If you add a custom field to your standard object then it's likely you'll want to include it in your reports. This is very simple, since all new fields are instantly available in the "[objectName] Extension" folder in existing subject areas. The following two minute video demonstrates this. Custom Subject Areas for Standard Objects You can create your own subject areas for use in analytics and reporting via Application Composer. An example use-case could be to simplify the seeded subject areas, since they sometimes contain complex data fields and internal values that could confuse business users. One thing to note is that you cannot create subject areas in a sandbox, as it is not supported by BI, so once your custom object is tested and complete you'll need to publish the sandbox before moving forwards. The subject area creation processes is essentially two-fold. Once the request is submitted the ADF artifacts are generated, then secondly the related metadata is sent to the BI presentation server API's to make the updates there. One thing to note is that this second step may take up to ten minutes to complete. Once finished the status of the custom subject area request should show as 'OK' and it is then ready for use. Within the creation processes wizard-like steps there are three concepts worth highlighting: Date Flattening - this feature permits the roll up of reports at various date levels, such as data by week, month, quarter, or year. You simply check the box to enable it for that date field. Measures - these are your own functions that you can build into the custom subject area. They are related to the field data type and include min-max for dates, and sum(), avg(), and count() for  numeric fields. Implicit Facts - used to make the BI metadata join between your object fields and the calculated measure fields. The advice is to choose the most frequently used measure to ensure consistency. This video shows a simple example, where a simplified subject area is created for the customer 'Contact' standard object, picking just a few fields upon which users can then create reports. Custom Objects Custom subject areas support three types of custom objects. First is a simple standalone custom object and for which the same process mentioned above applies. The next is a custom child object created on a standard object parent, and finally a custom object that is related to a parent object - usually through a dynamic choice list. Whilst the steps in each of these last two are mostly the same, there are differences in the way you choose the objects and their fields. This is illustrated in the videos below.The first video shows the process for creating a custom subject area for a simple standalone custom object. This second video demonstrates how to create custom subject areas for custom objects that are of parent:child type, as well as those those with dynamic-choice-list relationships. &lt;span id=&quot;XinhaEditingPostion&quot;&gt;&lt;/span&gt; Flexfields Dynamic and Extensible Flexfields satisfy a similar requirement as custom fields (for Application Composer), with flexfields common across the Fusion Financials, Supply Chain and Procurement, and HCM applications. The basic principle is when you enable and configure your flexfields, in the edit page under each segment region (for both global and context segments) there is a BI Enabled check box. Once this is checked and you've completed your configuration, you run the Scheduled Process job named 'Import Oracle Fusion Data Extensions for Transactional Business Intelligence' to generate and migrate the related BI artifacts and data. This applies for dynamic, key, and extensible flexfields. Of course there is more to consider in terms of how you wish your flexfields to be implemented and exposed in your reports, and details are given in Chapter 4 of the Extending Applications guide.

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• Custom page sizes in paging dropdown in Telerik RadGrid

  Working with Telerik RadControls for ASP.NET AJAX is actually quite easy and the initial effort to get started with the control suite is very low. Meaning that you can easily get good result with little time. But there are usually cases where you have to go a little further and dig a little bit deeper than the standard scenarios. In this article I am going to describe how you can customize the default values (10, 20 and 50) of the drop-down list in the paging element of RadGrid. Get control over the displayed page sizes while using numeric paging... The default page sizes are good but not always good enough The paging feature in RadGrid offers you 3, well actually 4, possible page sizes in the drop-down element out-of-the box, which are 10, 20 or 50 items. You can get a fourth option by specifying a value different than the three standards for the PageSize attribute, ie. 35 or 100. The drawback in that case is that it is the initial page size. Certainly, the available choices could be more flexible or even a little bit more intelligent. For example, by taking the total count of records into consideration. There are some interesting scenarios that would justify a customized page size element: A low number of records, like 14 or similar shouldn't provide a page size of 50, A high total count of records (ie: 300+) should offer more choices, ie: 100, 200, 500, or display of all records regardless of number of records I am sure that you might have your own requirements, and I hope that the following source code snippets might be helpful. Wiring the ItemCreated event In order to adjust and manipulate the existing RadComboBox in the paging element we have to handle the OnItemCreated event of RadGrid. Simply specify your code behind method in the attribute of the RadGrid tag, like so: <telerik:RadGrid ID="RadGridLive" runat="server" AllowPaging="true" PageSize="20"    AllowSorting="true" AutoGenerateColumns="false" OnNeedDataSource="RadGridLive_NeedDataSource"    OnItemDataBound="RadGrid_ItemDataBound" OnItemCreated="RadGrid_ItemCreated">    <ClientSettings EnableRowHoverStyle="true">        <ClientEvents OnRowCreated="RowCreated" OnRowSelected="RowSelected" />        <Resizing AllowColumnResize="True" AllowRowResize="false" ResizeGridOnColumnResize="false"            ClipCellContentOnResize="true" EnableRealTimeResize="false" AllowResizeToFit="true" />        <Scrolling AllowScroll="true" ScrollHeight="360px" UseStaticHeaders="true" SaveScrollPosition="true" />        <Selecting AllowRowSelect="true" />    </ClientSettings>    <MasterTableView DataKeyNames="AdvertID">        <PagerStyle AlwaysVisible="true" Mode="NextPrevAndNumeric" />        <Columns>            <telerik:GridBoundColumn HeaderText="Listing ID" DataField="AdvertID" DataType="System.Int32"                SortExpression="AdvertID" UniqueName="AdvertID">                <HeaderStyle Width="66px" />            </telerik:GridBoundColumn>             <!--//  ... and some more columns ... -->         </Columns>    </MasterTableView></telerik:RadGrid> To provide a consistent experience for your visitors it might be helpful to display the page size selection always. This is done by setting the AlwaysVisible attribute of the PagerStyle element to true, like highlighted above. Customize the values of page size Your delegate method for the ItemCreated event should look like this: protected void RadGrid_ItemCreated(object sender, GridItemEventArgs e){    if (e.Item is GridPagerItem)    {        var dropDown = (RadComboBox)e.Item.FindControl("PageSizeComboBox");        var totalCount = ((GridPagerItem)e.Item).Paging.DataSourceCount;        var sizes = new Dictionary<string, string>() {            {"10", "10"},            {"20", "20"},            {"50", "50"}        };        if (totalCount > 100)        {            sizes.Add("100", "100");        }        if (totalCount > 200)        {            sizes.Add("200", "200");        }        sizes.Add("All", totalCount.ToString());        dropDown.Items.Clear();        foreach (var size in sizes)        {            var cboItem = new RadComboBoxItem() { Text = size.Key, Value = size.Value };            cboItem.Attributes.Add("ownerTableViewId", e.Item.OwnerTableView.ClientID);            dropDown.Items.Add(cboItem);        }        dropDown.FindItemByValue(e.Item.OwnerTableView.PageSize.ToString()).Selected = true;    }} It is important that we explicitly check the event arguments for GridPagerItem as it is the control that contains the PageSizeComboBox control that we want to manipulate. To keep the actual modification and exposure of possible page size values flexible I am filling a Dictionary with the requested 'key/value'-pairs based on the number of total records displayed in the grid. As a final step, ensure that the previously selected value is the active one using the FindItemByValue() method. Of course, there might be different requirements but I hope that the snippet above provide a first insight into customized page size value in Telerik's Grid. The Grid demos describe a more advanced approach to customize the Pager.

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• How can I estimate the entropy of a password?

  - by Wug

  Having read various resources about password strength I'm trying to create an algorithm that will provide a rough estimation of how much entropy a password has. I'm trying to create an algorithm that's as comprehensive as possible. At this point I only have pseudocode, but the algorithm covers the following: password length repeated characters patterns (logical) different character spaces (LC, UC, Numeric, Special, Extended) dictionary attacks It does NOT cover the following, and SHOULD cover it WELL (though not perfectly): ordering (passwords can be strictly ordered by output of this algorithm) patterns (spatial) Can anyone provide some insight on what this algorithm might be weak to? Specifically, can anyone think of situations where feeding a password to the algorithm would OVERESTIMATE its strength? Underestimations are less of an issue. The algorithm: // the password to test password = ? length = length(password) // unique character counts from password (duplicates discarded) uqlca = number of unique lowercase alphabetic characters in password uquca = number of uppercase alphabetic characters uqd = number of unique digits uqsp = number of unique special characters (anything with a key on the keyboard) uqxc = number of unique special special characters (alt codes, extended-ascii stuff) // algorithm parameters, total sizes of alphabet spaces Nlca = total possible number of lowercase letters (26) Nuca = total uppercase letters (26) Nd = total digits (10) Nsp = total special characters (32 or something) Nxc = total extended ascii characters that dont fit into other categorys (idk, 50?) // algorithm parameters, pw strength growth rates as percentages (per character) flca = entropy growth factor for lowercase letters (.25 is probably a good value) fuca = EGF for uppercase letters (.4 is probably good) fd = EGF for digits (.4 is probably good) fsp = EGF for special chars (.5 is probably good) fxc = EGF for extended ascii chars (.75 is probably good) // repetition factors. few unique letters == low factor, many unique == high rflca = (1 - (1 - flca) ^ uqlca) rfuca = (1 - (1 - fuca) ^ uquca) rfd = (1 - (1 - fd ) ^ uqd ) rfsp = (1 - (1 - fsp ) ^ uqsp ) rfxc = (1 - (1 - fxc ) ^ uqxc ) // digit strengths strength = ( rflca * Nlca + rfuca * Nuca + rfd * Nd + rfsp * Nsp + rfxc * Nxc ) ^ length entropybits = log_base_2(strength) A few inputs and their desired and actual entropy_bits outputs: INPUT DESIRED ACTUAL aaa very pathetic 8.1 aaaaaaaaa pathetic 24.7 abcdefghi weak 31.2 H0ley$Mol3y_ strong 72.2 s^fU¬5ü;y34G< wtf 88.9 [a^36]* pathetic 97.2 [a^20]A[a^15]* strong 146.8 xkcd1** medium 79.3 xkcd2** wtf 160.5 * these 2 passwords use shortened notation, where [a^N] expands to N a's. ** xkcd1 = "Tr0ub4dor&3", xkcd2 = "correct horse battery staple" The algorithm does realize (correctly) that increasing the alphabet size (even by one digit) vastly strengthens long passwords, as shown by the difference in entropy_bits for the 6th and 7th passwords, which both consist of 36 a's, but the second's 21st a is capitalized. However, they do not account for the fact that having a password of 36 a's is not a good idea, it's easily broken with a weak password cracker (and anyone who watches you type it will see it) and the algorithm doesn't reflect that. It does, however, reflect the fact that xkcd1 is a weak password compared to xkcd2, despite having greater complexity density (is this even a thing?). How can I improve this algorithm? Addendum 1 Dictionary attacks and pattern based attacks seem to be the big thing, so I'll take a stab at addressing those. I could perform a comprehensive search through the password for words from a word list and replace words with tokens unique to the words they represent. Word-tokens would then be treated as characters and have their own weight system, and would add their own weights to the password. I'd need a few new algorithm parameters (I'll call them lw, Nw ~= 2^11, fw ~= .5, and rfw) and I'd factor the weight into the password as I would any of the other weights. This word search could be specially modified to match both lowercase and uppercase letters as well as common character substitutions, like that of E with 3. If I didn't add extra weight to such matched words, the algorithm would underestimate their strength by a bit or two per word, which is OK. Otherwise, a general rule would be, for each non-perfect character match, give the word a bonus bit. I could then perform simple pattern checks, such as searches for runs of repeated characters and derivative tests (take the difference between each character), which would identify patterns such as 'aaaaa' and '12345', and replace each detected pattern with a pattern token, unique to the pattern and length. The algorithmic parameters (specifically, entropy per pattern) could be generated on the fly based on the pattern. At this point, I'd take the length of the password. Each word token and pattern token would count as one character; each token would replace the characters they symbolically represented. I made up some sort of pattern notation, but it includes the pattern length l, the pattern order o, and the base element b. This information could be used to compute some arbitrary weight for each pattern. I'd do something better in actual code. Modified Example: Password: 1234kitty$$$$$herpderp Tokenized: 1 2 3 4 k i t t y $ $ $ $ $ h e r p d e r p Words Filtered: 1 2 3 4 @W5783 $ $ $ $ $ @W9001 @W9002 Patterns Filtered: @P[l=4,o=1,b='1'] @W5783 @P[l=5,o=0,b='$'] @W9001 @W9002 Breakdown: 3 small, unique words and 2 patterns Entropy: about 45 bits, as per modified algorithm Password: correcthorsebatterystaple Tokenized: c o r r e c t h o r s e b a t t e r y s t a p l e Words Filtered: @W6783 @W7923 @W1535 @W2285 Breakdown: 4 small, unique words and no patterns Entropy: 43 bits, as per modified algorithm The exact semantics of how entropy is calculated from patterns is up for discussion. I was thinking something like: entropy(b) * l * (o + 1) // o will be either zero or one The modified algorithm would find flaws with and reduce the strength of each password in the original table, with the exception of s^fU¬5ü;y34G<, which contains no words or patterns.

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• Tweaking Hudson memory usage

  - by rovarghe

  Hudson 3.1 has some performance optimizations that greatly reduces its memory footprint. Prior to this Hudson used to always hold the entire data model (all jobs and all builds) in memory which affected scalability. Some installations configured heap sizes in excess of 1GB to counteract this. Hudson 3.1.x maintains an MRU cache and only loads jobs and builds as they are required. Because of the inability to change existing APIs and be backward compatible with plugins, there were limits to how far we could go with this approach. Memory optimizations almost always come with a related cost, in this case its additional I/O that has to be performed to load data on request. On a small site that has frequent traffic, this is usually not noticeable since the MRU cache will usually hold on to all the data. A large site with infrequent traffic might experience some delays when the first request hits the server after a long gap. If you have a large heap and are able to allocate more memory, the cache settings can be adjusted to take advantage of this and even go back to pre-3.1 behavior. All the cache settings can be passed as options to the JVM container (Tomcat or the default Jetty container) using the -D option. There are two caches, independant of each other, one for Jobs and the other for Builds. For the jobs cache: hudson.jobs.cache.evict_in_seconds ( default=60 ) Seconds from last access (could be because of a servlet request or a background cron thread) a job should be purged from the cache. Set this to 0 to never purge based on time. hudson.jobs.cache.initial_capacity ( default=1024 ) Initial number of jobs the cache can accomodate. Setting this to the number of jobs you typically display on your Hudson landing page or home page will speed up consecutive access to that page. If the default is too large you may consider downsizing and using that memory for the Builds cache instead. hudson.jobs.cache.max_entries ( default=1024) Maximum number of jobs in the cache. The default is large enough for most installations, but if you find I/O activity when always accessing the hudson home page you might consider increasing this, but first verify if the I/O is caused by frequent eviction (see above), rather than by the cache not being large enough. For the builds cache: The builds cache is used to store Build objects as they are read from storage. Typically this happens when a user drills down into the details of a particular Job from the hudson hom epage. The cache is shared among builds for different jobs since in most installations all jobs are not accessed with the same frequency, so a per-job builds cache would be a waste of memory. hudson.job.builds.cache.evict_in_seconds ( default=60 ) Same as the equivalent Job cache, applied to Build. hudson.job.builds.cache.initial_capacity" ( default=512 ) Same as equivalent Job cache setting. Note the smaller initial size. If your site stores a large number of builds and has frequent access to more builds you might consider bumping this up. hudson.job.builds.cache.max_entries ( default=10240 ) The default max is large enough for most installations, the builds cache has bigger sized objects, so be careful about increasing the upper limit on this. See section on monitoring below. Sample usage: java -jar hudson-war-3.1.2-SNAPSHOT.war -Dhudson.jobs.cache.evict_in_seconds=300 \ -Dhudson.job.builds.cache.evict_in_seconds=300 Monitoring cache usage The 'jmap' tool that comes with the JDK can be used to monitor cache performance in an indirect way by looking at the number of Job and Build objects in each cache. Find the PID of the hudson instance and run $ jmap -histo:live <pid | grep 'hudson.model.*Lazy.*Key$' Here's a sample output: num #instances #bytes class name 523: 28 896 hudson.model.RunMap$LazyRunValue$Key 1200: 3 96 hudson.model.LazyTopLevelItem$Key These are the keys to the Jobs (LazyTopLevelItem$Key) and Builds (RunMap$LazyRunValue$Key) in the caches, so counting the number of keys is a good indicator of the number of items in the cache at any given moment. The size in bytes can be ignored, they are just the size of the keys, not the actual sizes of the objects they hold. Those sizes can only be obtained with a profiler. With the output above we can conclude that there are 3 jobs and 28 builds in memory. The 28 builds can all be from 1 job or all 3 jobs. Over time on an idle system, these should get evicted and memory cache should be empty. In practice, because of background cron threads and triggers, jobs rarely fall down to zero. Access of a job or a build by a cron thread resets the eviction timer.

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• ????: PostgreSQL??Oracle RAC????

  - by Kumiko Fujita

  ?????????????????????????????????????????????????????????????????????????? ????????????????????????? * * * ?????????????????????????????????????DBMS??????????????????????????????DBMS????????????????????????????????????????????? 1. ???? ?????????????????????????????????????????????????????????????????????1?????? ???????????????? ?????????????????????????????DB???????OSS?PostgreSQL?????AP?????DB??????????????????? ???????? ?????10?????????????GB????????????????????????????DB?????????????????????????? ?????????????3,500?????????24????????????????????????????????????? ??AP?????????????????????????????????????????DB??PostgreSQL??????????????????PostgreSQL ????????????????????Vacuum????????????????????????????????????????????????????? ??????????????????PostgreSQL?OSS??????????????????????????????????????????????????DB MS??????Oracle Database 11gR2???????????????????????500GB???????????????????????????Partitioning ???????? Oracle Database Enterprise Edition?????????????????????????????????????????????? ????SAN?????Active/Standby???HA????????????????? 2. ????? 2.1. ???? PostgreSQL??????Oracle??????????????????????????????????????????????????????TEXT????? ????????????????????Oracle??????????????????????????PostgreSQL??csv???????Oracle Database?SQL*Loa der????????????? ??????????????????????????????DB??????????????Windows?Liunx??????????????????????? ????????????????????????????????????????????????? ?????????????PostgreSQL?NULL?????''????????????Oracle Database???????????????????????? ?????????? table { border-collapse: collapse; } th { border: solid 1px #666666; color: #000000; background-color: #ff9999; } td { border: solid 1px #666666; color: #000000; background-color: #ffffff; } ???? PostgreSQL Oracle Database ??? CHAR(n) CHAR(n),CLOB VARCHAR(n) VARCHAR2(n),CLOB TEXT CLOB ??? NUMERIC NUMBER INTEGER NUMBER SMALLINT NUMBER BIGINT NUMBER REAL NUMBER DOUBLE PRECISION NUMBER ??? DATE DATE TIMESTAMP TIMESTAMP ????? Bytea BLOB LOB BFILE/SecureFiles ??? OID ROWID 2.2. ????? ?????????????PostgreSQL?Oracle Database??????????SQL???????????????????????????????????Postg reSQL?LIMIT?OFFSET??Oracle Database?????????????????????? LIMIT,OFFSET???SELECT?????? /* PostgreSQL LIMIT,OFFSET */ SELECT ??? FROM ????? ORDER BY ???? LIMIT 2 OFFSET 5; /* Oracle Database????? */ SELECT ??? FROM (SELECT ???, ROWNUM line_no FROM (SELECT??? FROM ????? OREDR BY ???? ) ) WHERE line_no BETWEEN 6 AND 7; ??????????????????????????????????????????????????????????????????????????? ?????????????????? ????????????????????????????????????????????????Oracle Database??????????????????????Oracle Database????WHERE??????????????????????????????????????????????????????WHERE?????????????????????? 3. ???? ???????????????????????30%~40%????????????????????80%????????????????????? ?ITpro???:???????4????? ??????????????????????????????????? ·?????·??????????????????????????? ·????????????????????????????? ????????????????????????????????????????? 3.1. ??????? ????????????????????????????????????????·??????????????????????????????????? ???????????????????????????????????????????????????????·?????????????????? ???????????????????????????? (1)???????????????????? (2)???????????????????????????????????????????? (3)??????????????? (4)???????????????????????????????? ???????????·???????????????????????????????????????????????????????????????? ????????????????????? ????????·?? table { border-collapse: collapse; } th { border: solid 1px #666666; color: #000000; background-color: #ff9999; } td { border: solid 1px #666666; color: #000000; background-color: #ffffff; } ?? ?? ?? (1) ?????????? ????????????·???????????????????????? (2) ???????????????????? ?????????????????????????????? (3) ?????4????????????????? ???????????????????????DB????????? (4) ??????????(3)???????? ???????????????????????? ?????????????????????GB???????????????????????????????????????????(3)?????????? ??????? ??????????????????????????????????????????????csv??????????SQL*Loader?Oracle Database?????????????????????Oracle Database???????????????????????????INSERT????????????? ???????????????????????????????????????????????????????????????????????????? ?????????????????????? 3.2. ????? ???????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 3.3. ????? ??????????????????????????????????????????????????????????????????????????? ??????????????????????? DBMS????????????????????????SQL??????????????????????????????????????????????????PostgreSQL?Oracle Database???????????MVCC?????????????????????????Read Committed??????????????????????????????????????????????????????????????????????????????????? ????????????????DBMS?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 4. ??? PostgreSQL??Oracle Database?????????????????????????????? ????????????·????????????????????????????????????? ??????4???????????????????????·??????????????????? ???????????????????????????????????????????????? ?????????????????????????????????????????????DBMS???????????????????DBMS???????? ?????SQL?????????????????????????????DB???????????????????????????? ???????????????????????????DBMS?????????????????????????????????????????????????????? ??????????????????????????????

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• MKMapView memory usage grows out of control with setRegion: calls

  - by Kurt

  Hi, I have a single MKMapView instance that I have programmatically added to a UIView. As part of the UI, the user can cycle through a list of addresses and the map view is updated to show the correct map for each address as the user goes through them. I create the map view once, and simply change what it displays with setRegion:animated:. The problem is that each time the map is changed to show a new address, the memory usage of my program increases by 200K-500K (as reported by Memory Monitor in Instruments). According to Object Allocations, it appears that a lot of 1.0K Mallocs are happening each time, and the Extended Detail pane for these 1.0K allocations shows that the Responsible Caller is convert_image_data and the Extended Detail pane shows that this is the result of [MKMapTileView drawLayer:inContext:]. So, seems likely to me that the memory usage is due to MKMapView not freeing memory it uses to redraw the map each time. In fact, when I don't display the map at all (by not even adding it as a subview of my main UIView) but still cycle through the addresses (which changes various UILabels and other displayed info) the memory usage for the app does NOT increase. If I add the map view but never update it with setRegion:, the memory also does NOT increase when changing to a new address. One more bit of info: if I go to a new address (and therefore ask the map to display the new address) the memory jumps as described above. However, if I go back to an address that was already displayed, the memory does not jump when the map redraws with the old address. Also, this happens on iPad (real device) with 3.2 and on iPhone (again, real device) with 3.1.2. Here's how I initialize the MKMapView (I only do this once): CGRect mapFrame; mapFrame.origin.y = 460; // yes, magic numbers. just for testing. mapFrame.origin.x = 0; mapFrame.size.height = 500; mapFrame.size.width = 768; mapView = [[MKMapView alloc] initWithFrame:mapFrame]; mapView.delegate = self; [self.view insertSubview:mapView atIndex:0]; And in response to the user selecting an address, I set the map like so: MKCoordinateRegion region; MKCoordinateSpan span; span.latitudeDelta=kStreetMapSpan; // 0.003 span.longitudeDelta=kStreetMapSpan; // 0.003 region.center = address.coords; // coords is CLLocationCoordinate2D region.span = span; mapView.region.span = span; [mapView setRegion:region animated:NO]; Any thoughts? I've scoured the net but haven't seen mention of this problem, and I've reached the limits of my Instruments knowledge. Thanks for any ideas.

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• delta-dictionary/dictionary with revision awareness in python?

  - by shabbychef

  I am looking to create a dictionary with 'roll-back' capabilities in python. The dictionary would start with a revision number of 0, and the revision would be bumped up only by explicit method call. I do not need to delete keys, only add and update key,value pairs, and then roll back. I will never need to 'roll forward', that is, when rolling the dictionary back, all the newer revisions can be discarded, and I can start re-reving up again. thus I want behaviour like: >>> rr = rev_dictionary() >>> rr.rev 0 >>> rr["a"] = 17 >>> rr[('b',23)] = 'foo' >>> rr["a"] 17 >>> rr.rev 0 >>> rr.roll_rev() >>> rr.rev 1 >>> rr["a"] 17 >>> rr["a"] = 0 >>> rr["a"] 0 >>> rr[('b',23)] 'foo' >>> rr.roll_to(0) >>> rr.rev 0 >>> rr["a"] 17 >>> rr.roll_to(1) Exception ... Just to be clear, the state associated with a revision is the state of the dictionary just prior to the roll_rev() method call. thus if I can alter the value associated with a key several times 'within' a revision, and only have the last one remembered. I would like a fairly memory-efficient implementation of this: the memory usage should be proportional to the deltas. Thus simply having a list of copies of the dictionary will not scale for my problem. One should assume the keys are in the tens of thousands, and the revisions are in the hundreds of thousands. We can assume the values are immutable, but need not be numeric. For the case where the values are e.g. integers, there is a fairly straightforward implementation (have a list of dictionaries of the numerical delta from revision to revision). I am not sure how to turn this into the general form. Maybe bootstrap the integer version and add on an array of values? all help appreciated.

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• Lots of questions about file I/O (reading/writing message strings)

  - by Nazgulled

  Hi, For this university project I'm doing (for which I've made a couple of posts in the past), which is some sort of social network, it's required the ability for the users to exchange messages. At first, I designed my data structures to hold ALL messages in a linked list, limiting the message size to 256 chars. However, I think my instructors will prefer if I save the messages on disk and read them only when I need them. Of course, they won't say what they prefer, I need to make a choice and justify the best I can why I went that route. One thing to keep in mind is that I only need to save the latest 20 messages from each user, no more. Right now I have an Hash Table that will act as inbox, this will be inside the user profile. This Hash Table will be indexed by name (the user that sent the message). The value for each element will be a data structure holding an array of size_t with 20 elements (20 messages like I said above). The idea is to keep track of the disk file offsets and bytes written. Then, when I need to read a message, I just need to use fseek() and read the necessary bytes. I think this could work nicely... I could use just one single file to hold all messages from all users in the network. I'm saying one single file because a colleague asked an instructor about saving the messages from each user independently which he replied that it might not be the best approach cause the file system has it's limits. That's why I'm thinking of going the single file route. However, this presents a problem... Since I only need to save the latest 20 messages, I need to discard the older ones when I reach this limit. I have no idea how to do this... All I know is about fread() and fwrite() to read/write bytes from/to files. How can I go to a file offset and say "hey, delete the following X bytes"? Even if I could do that, there's another problem... All offsets below that one will be completely different and I would have to process all users mailboxes to fix the problem. Which would be a pain... So, any suggestions to solve my problems? What do you suggest?

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