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• Open Source but not Free Software (or vice versa)

  - by TRiG

  The definition of "Free Software" from the Free Software Foundation: “Free software” is a matter of liberty, not price. To understand the concept, you should think of “free” as in “free speech,” not as in “free beer.” Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software. More precisely, it means that the program's users have the four essential freedoms: The freedom to run the program, for any purpose (freedom 0). The freedom to study how the program works, and change it to make it do what you wish (freedom 1). Access to the source code is a precondition for this. The freedom to redistribute copies so you can help your neighbor (freedom 2). The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this. A program is free software if users have all of these freedoms. Thus, you should be free to redistribute copies, either with or without modifications, either gratis or charging a fee for distribution, to anyone anywhere. Being free to do these things means (among other things) that you do not have to ask or pay for permission to do so. The definition of "Open Source Software" from the Open Source Initiative: Open source doesn't just mean access to the source code. The distribution terms of open-source software must comply with the following criteria: Free Redistribution The license shall not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license shall not require a royalty or other fee for such sale. Source Code The program must include source code, and must allow distribution in source code as well as compiled form. Where some form of a product is not distributed with source code, there must be a well-publicized means of obtaining the source code for no more than a reasonable reproduction cost preferably, downloading via the Internet without charge. The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated source code is not allowed. Intermediate forms such as the output of a preprocessor or translator are not allowed. Derived Works The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software. Integrity of The Author's Source Code The license may restrict source-code from being distributed in modified form only if the license allows the distribution of "patch files" with the source code for the purpose of modifying the program at build time. The license must explicitly permit distribution of software built from modified source code. The license may require derived works to carry a different name or version number from the original software. No Discrimination Against Persons or Groups The license must not discriminate against any person or group of persons. No Discrimination Against Fields of Endeavor The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research. Distribution of License The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties. License Must Not Be Specific to a Product The rights attached to the program must not depend on the program's being part of a particular software distribution. If the program is extracted from that distribution and used or distributed within the terms of the program's license, all parties to whom the program is redistributed should have the same rights as those that are granted in conjunction with the original software distribution. License Must Not Restrict Other Software The license must not place restrictions on other software that is distributed along with the licensed software. For example, the license must not insist that all other programs distributed on the same medium must be open-source software. License Must Be Technology-Neutral No provision of the license may be predicated on any individual technology or style of interface. These definitions, although they derive from very different ideologies, are broadly compatible, and most Free Software is also Open Source Software and vice versa. I believe, however, that it is possible for this not to be the case: It is possible for software to be Open Source without being Free, or to be Free without being Open Source. Questions Is my belief correct? Is it possible for software to fall into one camp and not the other? Does any such software actually exist? Please give examples. Clarification I've already accepted an answer now, but I seem to have confused a lot of people, so perhaps a clarification is in order. I was not asking about the difference between copyleft (or "viral", though I don't like that term) and non-copyleft ("permissive") licenses. Nor was I asking about your personal idiosyncratic definitions of "Free" and "Open". I was asking about "Free Software as defined by the FSF" and "Open Source Software as defined by the OSI". Are the two always the same? Is it possible to be one without being the other? And the answer, it seems, is that it's impossible to be Free without being Open, but possible to be Open without being Free. Thank you everyone who actually answered the question.

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• SQL SERVER – Solution – Puzzle – SELECT * vs SELECT COUNT(*)

  - by pinaldave

  Earlier I have published Puzzle Why SELECT * throws an error but SELECT COUNT(*) does not. This question have received many interesting comments. Let us go over few of the answers, which are valid. Before I start the same, let me acknowledge Rob Farley who has not only answered correctly very first but also started interesting conversation in the same thread. The usual question will be what is the right answer. I would like to point to official Microsoft Connect Items which discusses the same. RGarvao https://connect.microsoft.com/SQLServer/feedback/details/671475/select-test-where-exists-select tiberiu utan http://connect.microsoft.com/SQLServer/feedback/details/338532/count-returns-a-value-1 Rob Farley count(*) is about counting rows, not a particular column. It doesn’t even look to see what columns are available, it’ll just count the rows, which in the case of a missing FROM clause, is 1. “select *” is designed to return columns, and therefore barfs if there are none available. Even more odd is this one: select ‘blah’ where exists (select *) You might be surprised at the results… Koushik The engine performs a “Constant scan” for Count(*) where as in the case of “SELECT *” the engine is trying to perform either Index/Cluster/Table scans. amikolaj When you query ‘select * from sometable’, SQL replaces * with the current schema of that table. With out a source for the schema, SQL throws an error. so when you query ‘select count(*)’, you are counting the one row. * is just a constant to SQL here. Check out the execution plan. Like the description states – ‘Scan an internal table of constants.’ You could do ‘select COUNT(‘my name is adam and this is my answer’)’ and get the same answer. Netra Acharya SELECT * Here, * represents all columns from a table. So it always looks for a table (As we know, there should be FROM clause before specifying table name). So, it throws an error whenever this condition is not satisfied. SELECT COUNT(*) Here, COUNT is a Function. So it is not mandetory to provide a table. Check it out this: DECLARE @cnt INT SET @cnt = COUNT(*) SELECT @cnt SET @cnt = COUNT(‘x’) SELECT @cnt Naveen Select 1 / Select ‘*’ will return 1/* as expected. Select Count(1)/Count(*) will return the count of result set of select statement. Count(1)/Count(*) will have one 1/* for each row in the result set of select statement. Select 1 or Select ‘*’ result set will contain only 1 result. so count is 1. Where as “Select *” is a sysntax which expects the table or equauivalent to table (table functions, etc..). It is like compilation error for that query. Ramesh Hi Friends, Count is an aggregate function and it expects the rows (list of records) for a specified single column or whole rows for *. So, when we use ‘select *’ it definitely give and error because ‘*’ is meant to have all the fields but there is not any table and without table it can only raise an error. So, in the case of ‘Select Count(*)’, there will be an error as a record in the count function so you will get the result as ’1'. Try using : Select COUNT(‘RAMESH’) and think there is an error ‘Must specify table to select from.’ in place of ‘RAMESH’ Pinal : If i am wrong then please clarify this. Sachin Nandanwar Any aggregate function expects a constant or a column name as an expression. DO NOT be confused with * in an aggregate function.The aggregate function does not treat it as a column name or a set of column names but a constant value, as * is a key word in SQL. You can replace any value instead of * for the COUNT function.Ex Select COUNT(5) will result as 1. The error resulting from select * is obvious it expects an object where it can extract the result set. I sincerely thank you all for wonderful conversation, I personally enjoyed it and I am sure all of you have the same feeling. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: CodeProject, Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• Class Loading Deadlocks

  - by tomas.nilsson

  Mattis follows up on his previous post with one more expose on Class Loading Deadlocks As I wrote in a previous post, the class loading mechanism in Java is very powerful. There are many advanced techniques you can use, and when used wrongly you can get into all sorts of trouble. But one of the sneakiest deadlocks you can run into when it comes to class loading doesn't require any home made class loaders or anything. All you need is classes depending on each other, and some bad luck. First of all, here are some basic facts about class loading: 1) If a thread needs to use a class that is not yet loaded, it will try to load that class 2) If another thread is already loading the class, the first thread will wait for the other thread to finish the loading 3) During the loading of a class, one thing that happens is that the <clinit method of a class is being run 4) The <clinit method initializes all static fields, and runs any static blocks in the class. Take the following class for example: class Foo { static Bar bar = new Bar(); static { System.out.println("Loading Foo"); } } The first time a thread needs to use the Foo class, the class will be initialized. The <clinit method will run, creating a new Bar object and printing "Loading Foo" But what happens if the Bar object has never been used before either? Well, then we will need to load that class as well, calling the Bar <clinit method as we go. Can you start to see the potential problem here? A hint is in fact #2 above. What if another thread is currently loading class Bar? The thread loading class Foo will have to wait for that thread to finish loading. But what happens if the <clinit method of class Bar tries to initialize a Foo object? That thread will have to wait for the first thread, and there we have the deadlock. Thread one is waiting for thread two to initialize class Bar, thread two is waiting for thread one to initialize class Foo. All that is needed for a class loading deadlock is static cross dependencies between two classes (and a multi threaded environment): class Foo { static Bar b = new Bar(); } class Bar { static Foo f = new Foo(); } If two threads cause these classes to be loaded at exactly the same time, we will have a deadlock. So, how do you avoid this? Well, one way is of course to not have these circular (static) dependencies. On the other hand, it can be very hard to detect these, and sometimes your design may depend on it. What you can do in that case is to make sure that the classes are first loaded single threadedly, for example during an initialization phase of your application. The following program shows this kind of deadlock. To help bad luck on the way, I added a one second sleep in the static block of the classes to trigger the unlucky timing. Notice that if you uncomment the "//Foo f = new Foo();" line in the main method, the class will be loaded single threadedly, and the program will terminate as it should. public class ClassLoadingDeadlock { // Start two threads. The first will instansiate a Foo object, // the second one will instansiate a Bar object. public static void main(String[] arg) { // Uncomment next line to stop the deadlock // Foo f = new Foo(); new Thread(new FooUser()).start(); new Thread(new BarUser()).start(); } } class FooUser implements Runnable { public void run() { System.out.println("FooUser causing class Foo to be loaded"); Foo f = new Foo(); System.out.println("FooUser done"); } } class BarUser implements Runnable { public void run() { System.out.println("BarUser causing class Bar to be loaded"); Bar b = new Bar(); System.out.println("BarUser done"); } } class Foo { static { // We are deadlock prone even without this sleep... // The sleep just makes us more deterministic try { Thread.sleep(1000); } catch(InterruptedException e) {} } static Bar b = new Bar(); } class Bar { static { try { Thread.sleep(1000); } catch(InterruptedException e) {} } static Foo f = new Foo(); }

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• How-to filter table filter input to only allow numeric input

  - by frank.nimphius

  In a previous ADF Code Corner post, I explained how to change the table filter behavior by intercepting the query condition in a query filter. See sample #30 at http://www.oracle.com/technetwork/developer-tools/adf/learnmore/index-101235.html In this OTN Harvest post I explain how to prevent users from providing invalid character entries as table filter criteria to avoid problems upon re-querying the table. In the example shown next, only numeric values are allowed for a table column filter. To create a table that allows data filtering, drag a View Object – or a data collection of a Web Service or JPA business service – from the DataControls panel and drop it as a table. Choose the Enable Filtering option in the Edit Table Columns dialog so the table renders with the column filter boxes displayed. The table filter fields are created using implicit af:inputText components that need to be customized for you to apply a custom filter input component, or to change the input behavior. To change the input filter, so only a defined set of input keys is allowed, you need to change the default filter field with your own af:inputText field to which you apply an af:clientListener tag that filters user keyboard entries. For this, in the Oracle JDeveloper visual editor, select the column which filter you want to change and expand the column node in the Oracle JDeveloper Structure Window. Part of the column definition is the Column facet node. Expand the facets so you see the filter facet entry. The filter facet is grayed out as there is no custom facet defined. In a next step, open theComponent Palette (ctrl+shift+P) and drag an Input Text component onto the facet. This demarks the first part in the filter customization. To make the custom filter component work, you need to map the af:inputText component value property to the ADF filter criteria that is exposed in the Expression Builder. Open the Expression Builder for the filter input component value property by clicking the arrow icon to its right. In the Expression Builder expand the JSP Objects | vs | filterCriteria node to select the attribute name represented by the table column. The vs entry is the name of a variable that is defined on the table and that grants you access to the table attributes. Now that the filter works as before – though using a custom filter input component – you can add the af:clientListener tag to your custom filter component – af:inputText – to call out to JavaScript when users type in the column filter field Point the client filter method property to a JavaScript function that you reference or add through using the af:resource tag and set the type property value to keyDown. <af:document id="d1">     <af:resource type="javascript" source="/js/filterHandler.js"/> … The filter definition looks as shown below <af:inputText label="Label 1" id="it1"                         value="#{vs.filterCriteria.Employe        <af:clientListener method="suppressCharacterInput"                                     type="keyDown"/> </af:inputText> The JavaScript code that you can use to either filter character inputs or numeric inputs is shown below. Just store this code in an external JavaScript (.js) file and reference it from the af:resource tag. //Allow numbers, cursor control keys and delete keys function suppressCharacterInput(evt) {     var _keyCode = evt.getKeyCode();     var _filterField = evt.getCurrentTarget();     var _oldValue = _filterField.getValue();     if (!((_keyCode < 57) ||(_keyCode > 96 && _keyCode < 105))) {         _filterField.setValue(_oldValue);         evt.cancel();     } } //Allow characters, cursor control keys and delete keys function suppressNumericInput(evt) {  var _keyCode = evt.getKeyCode();  var _filterField = evt.getCurrentTarget();  var _oldValue = _filterField.getValue();  //check for numbers  if ((_keyCode < 57 && _keyCode > 47) ||      (_keyCode > 96 && _keyCode < 105)){     _filterField.setValue(_oldValue);     evt.cancel();   } } But what if browsers don't allow JavaScript ? Don't worry about this. If browsers would not support JavaScript then ADF Faces as a whole would not work and you had a different problem.

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• Convert a PDF eBook to ePub Format

  - by Matthew Guay

  Would you like to read a PDF eBook on an eReader or mobile device, but aren’t happy with the performance? Here’s how you can convert your PDFs to the popular ePub format so you can easily read them on any device. PDFs are a popular format for eBooks since they render the same on any device and can preserve the exact layout of the print book.  However, this benefit is their major disadvantage on mobile devices, as you often have to zoom and pan back and forth to see everything on the page.  ePub files, on the other hand, are an increasingly popular option. They can reflow to fill your screen instead of sticking to a strict layout style.  With the free Calibre program, you can quickly convert your PDF eBooks to ePub format. Getting Started Download the Calibre installer (link below) for your operating system, and install as normal.  Calibre works on recent versions of Windows, OS X, and Linux.  The Calibre installer is very streamlined, so the install process was quite quick. Calibre is a great application for organizing your eBooks.  It can automatically sort your books by their metadata, and even display their covers in a Coverflow-style viewer. To add an eBook to your library, simply drag-and-drop the file into the Calibre window, or click Add books at the top.  Here you can choose to add all the books from a folder and more. Calibre will then add the book(s) to your library, import the associated metadata, and organize them in the catalog. Convert your Books Once you’ve imported your books into Calibre, it’s time to convert them to the format you want.  Select the book or books you want to convert, and click Convert E-books.  Select whether you want to convert them individually or bulk convert them. The convertor window has lots of options, so you can get your ePub book exactly like you want.  You can simply click Ok and go with the defaults, or you can tweak the settings. Do note that the conversion will only work successfully with PDFs that contain actual text.  Some PDFs are actually images scanned in from the original books; these will appear just like the PDF after the conversion, and won’t be any easier to read. On the first tab, you’ll notice that Calibri will repopulate most of the metadata fields with info from your PDF.  It will also use the first page of the PDF as the cover.  Edit any of the information that may be incorrect, and add any additional information you want associated with the book. If you want to convert your eBook to a different format other than ePub, Calibri’s got you covered, too.  On the top right, you can choose to output the converted eBook into a many different file formats, including the Kindle-friendly MOBI format. One other important settings page is the Structure Detection tab.  Here you can choose to have it remove headers and footers in the converted book, as well as automatically detect chapter breaks. Click Ok when you’ve finished choosing your settings and Calibre will convert the book.  This may take a few minutes, depending on the size of the PDF.  If the conversion seems to be taking too long, you can click Show job details for more information on the progress.   The conversion usually works good, but we did have one job freeze on us.  When we checked the job details, it indicated that the PDF was copy-protected.  Most PDF eBooks, however, worked fine. Now, back in the main Calibri window, select your book and save it to disk.  You can choose to save only the EPUB format, or you can select Save to disk to save all formats of the book to your computer. You can also view the ePub file directly in Calibri’s built-in eBook viewer.  This is the PDF book we converted, and it looks fairly good in the converted format.  It does have some odd line breaks and some misplaced numbers, but on the whole, the converted book is much easier to read, especially on small mobile devices.   Even images get included inline, so you shouldn’t be missing anything from the original eBook. Conclusion Calibri makes it simple to read your eBooks in any format you need. It is a project that is in constant development, and updates regularly adding better stability and features.  Whether you want to ready your PDF eBooks on a Sony Reader, Kindle, netbook or Smartphone, your books will now be more accessible than ever.  And with thousands of free PDF eBooks out there, you’ll be sure to always have something to read. If you’d like some Geeky PDF eBooks, Microsoft Press is offering a number of free PDF eBooks right now.  Check them out at this link (Account Required). Download the Calibre eBook program Similar Articles Productive Geek Tips Format a String as Currency in C#Convert Older Excel Documents to Excel 2007 FormatShare OneNote 2010 Notebooks with OneNote 2007Install an RPM Package on Ubuntu LinuxConvert PDF Files to Word Documents and Other Formats TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips HippoRemote Pro 2.2 Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Nice Websites To Watch TV Shows Online 24 Million Sites Windows Media Player Glass Icons (icons we like) How to Forecast Weather, without Gadgets Outlook Tools, one stop tweaking for any Outlook version Zoofs, find the most popular tweeted YouTube videos

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• SQL SERVER – Planned and Unplanned Availablity Group Failovers – Notes from the Field #031

  - by Pinal Dave

  [Note from Pinal]: This is a new episode of Notes from the Fields series. AlwaysOn is a very complex subject and not everyone knows many things about this. The matter of the fact is there is very little information available on this subject online and not everyone knows everything about this. This is why when a very common question related to AlwaysOn comes, people get confused. In this episode of the Notes from the Field series database expert John Sterrett (Group Principal at Linchpin People) explains a very common issue DBAs and Developer faces in their career and is related to Planned and Unplanned Availablity Group Failovers. Linchpin People are database coaches and wellness experts for a data driven world. Read the experience of John in his own words. Whenever a disaster occurs it will be a stressful scenario regardless of how small or big the disaster is. This gets multiplied when it is your first time working with newer technology or the first time you are going through a disaster without a proper run book. Today, were going to help you establish a run book for creating a planned failover with availability groups. To make today’s session simple were going to have two instances of SQL Server 2012 included in an availability group and walk through the steps of doing an unplanned failover.  We will focus on using the user interface and T-SQL to complete the failovers. We are going to use a two replica Availability Group where each replica is in another location. Therefore, we will be covering Asynchronous (non automatic failover) the following is a breakdown of our availability group utilized today. Seeing the following screen might be scary the first time you come across an unplanned failover.  It looks like our test database used in this Availability Group is not functional and it currently isn’t. The database status is not synchronizing which makes sense because the primary replica went down so it couldn’t synchronize. With that said, we can still failover and make it functional while we troubleshoot why we lost our primary replica. To start we are going to right click on the availability group that needs to be restarted and select failover. This will bring up the following wizard, which will walk you through several steps needed to complete the failover using the graphical user interface provided with SQL Server Management Studio (SSMS). You are going to see warning messages simply because we are in Asynchronous commit mode and can not guarantee ‘no data loss’ when we do failover. Just incase you missed it; you get another screen warning you about potential data loss because we are in Asynchronous mode. Next we get to connect to the specific replica we want to become the primary replica after the failover occurs. In our case, we only have two replicas so this is trivial. In order to failover, it’s required to connect to the replica that will become primary.  The following screen shows that the connection has been made successfully. Next, you will see the final summary screen. Once again, this reminds you that the failover action will cause data loss as were using Asynchronous commit mode due to the distance between instances used for disaster recovery. Finally, once the failover is completed you will see the following screen. If you followed along this long you might be wondering what T-SQL scripts are generated for clicking through all the sections of the wizard. If you have used Database Mirroring in the past you might be surprised.  It’s not too different, which makes sense because the data is being replicated via SQL Server endpoints just like the good old database mirroring. Now were going to take a look at how to do a failover with just T-SQL. First, were going to need to open a new query window and run our query in SQLCMD mode. Just incase you haven’t used SQLCMD mode before we will show you how to enable it below. Now you can run the following statement. Notice, we connect to the replica we want to become primary after failover and specify to force failover to allow data loss. We can use the following script to failback over when our primary instance comes back online. -- YOU MUST EXECUTE THE FOLLOWING SCRIPT IN SQLCMD MODE. :Connect SQL2012PROD1 ALTER AVAILABILITY GROUP [AGSQL2] FORCE_FAILOVER_ALLOW_DATA_LOSS; GO Are your servers running at optimal speed or are you facing any SQL Server Performance Problems? If you want to get started with the help of experts read more over here: Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• CLR via C# 3rd Edition is out

  - by Abhijeet Patel

  Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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• Passing the CAML thru the EY of the NEEDL

  - by PointsToShare

  © 2011 By: Dov Trietsch. All rights reserved Passing the CAML thru the EY of the NEEDL Definitions: CAML (Collaborative Application Markup Language) is an XML based markup language used in Microsoft SharePoint technologies  Anonymous: A camel is a horse designed by committee  Dov Trietsch: A CAML is a HORS designed by Microsoft  I was advised against putting any Camel and Sphinx rhymes in here. Look it up in Google!  _____ Now that we have dispensed with the dromedary jokes (BTW, I have many more, but they are not fit to print!), here is an interesting problem and its solution.  We have built a list where the title must be kept unique so I needed to verify the existence (or absence) of a list item with a particular title. Two methods came to mind:  1: Span the list until the title is found (result = found) or until the list ends (result = not found). This is an algorithm of complexity O(N) and for long lists it is a performance sucker. 2: Use a CAML query instead. Here, for short list we’ll encounter some overhead, but because the query results in an SQL query on the content database, it is of complexity O(LogN), which is significantly better and scales perfectly. Obviously I decided to go with the latter and this is where the CAML s--t hit the fan.   A CAML query returns a SPListItemCollection and I simply checked its Count. If it was 0, the item did not already exist and it was safe to add a new item with the given title. Otherwise I cancelled the operation and warned the user. The trouble was that I always got a positive. Most of the time a false positive. The count was greater than 0 regardles of the title I checked (except when the list was empty, which happens only once). This was very disturbing indeed. To solve my immediate problem which was speedy delivery, I reverted to the “Span the list” approach, but the problem bugged me, so I wrote a little console app by which I tested and tweaked and tested, time and again, until I found the solution. Yes, one can pass the proverbial CAML thru the ey of the needle (e’s missing on purpose).  So here are my conclusions:  CAML that does not work:  Note: QT is my quote:  char QT = Convert.ToChar((int)34); string titleQuery = "<Query>><Where><Eq>"; titleQuery += "<FieldRef Name=" + QT + "Title" + QT + "/>"; titleQuery += "<Value Type=" + QT + "Text" + QT + ">" + uniqueID + "</Value></Eq></Where></Query>"; titleQuery += "<ViewFields><FieldRef Name=" + QT + "Title" + QT + "/></ViewFields>";  Why? Even though U2U generates it, the <Query> and </Query> tags do not belong in the query that you pass. Start your query with the <Where> clause.  Also the <ViewFiels> clause does not belong. I used this clause to limit the returned collection to a single column, and I still wish to do it. I’ll show how this is done a bit later.   When you use the <Query> </Query> tags in you query, it’s as if you did not specify the query at all. What you get is the all inclusive default query for the list. It returns evey column and every item. It is expensive for both server and network because it does all the extra processing and eats plenty of bandwidth.   Now, here is the CAML that works  string titleQuery = "<Where><Eq>"; titleQuery += "<FieldRef Name=" + QT + "Title" + QT + "/>"; titleQuery += "<Value Type=" + QT + "Text" + QT + ">" + uniqueID + "</Value></Eq></Where>";  You’ll also notice that inside the unusable <ViewFields> clause above, we have a <FieldRef> clause. This is what we pass to the SPQuery object. Here is how:  SPQuery query = new SPQuery(); query.Query = titleQuery; query.ViewFields = "<FieldRef Name=" + QT + "Title" + QT + "/>"; query.RowLimit = 1; SPListItemCollection col = masterList.GetItems(query);  Two thing to note: we enter the view fields into the SPQuery object and we also limited the number of rows that the query returns. The latter is not always done, but in an existence test, there is no point in returning hundreds of rows. The query will now return one item or none, which is all we need in order to verify the existence (or non-existence) of items. Limiting the number of columns and the number of rows is a great performance enhancer. That’s all folks!!

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• SQL SERVER – SSIS Parameters in Parent-Child ETL Architectures – Notes from the Field #040

  - by Pinal Dave

  [Notes from Pinal]: SSIS is very well explored subject, however, there are so many interesting elements when we read, we learn something new. A similar concept has been Parent-Child ETL architecture’s relationship in SSIS. Linchpin People are database coaches and wellness experts for a data driven world. In this 40th episode of the Notes from the Fields series database expert Tim Mitchell (partner at Linchpin People) shares very interesting conversation related to how to understand SSIS Parameters in Parent-Child ETL Architectures. In this brief Notes from the Field post, I will review the use of SSIS parameters in parent-child ETL architectures. A very common design pattern used in SQL Server Integration Services is one I call the parent-child pattern.  Simply put, this is a pattern in which packages are executed by other packages.  An ETL infrastructure built using small, single-purpose packages is very often easier to develop, debug, and troubleshoot than large, monolithic packages.  For a more in-depth look at parent-child architectures, check out my earlier blog post on this topic. When using the parent-child design pattern, you will frequently need to pass values from the calling (parent) package to the called (child) package.  In older versions of SSIS, this process was possible but not necessarily simple.  When using SSIS 2005 or 2008, or even when using SSIS 2012 or 2014 in package deployment mode, you would have to create package configurations to pass values from parent to child packages.  Package configurations, while effective, were not the easiest tool to work with.  Fortunately, starting with SSIS in SQL Server 2012, you can now use package parameters for this purpose. In the example I will use for this demonstration, I’ll create two packages: one intended for use as a child package, and the other configured to execute said child package.  In the parent package I’m going to build a for each loop container in SSIS, and use package parameters to pass in a value – specifically, a ClientID – for each iteration of the loop.  The child package will be executed from within the for each loop, and will create one output file for each client, with the source query and filename dependent on the ClientID received from the parent package. Configuring the Child and Parent Packages When you create a new package, you’ll see the Parameters tab at the package level.  Clicking over to that tab allows you to add, edit, or delete package parameters. As shown above, the sample package has two parameters.  Note that I’ve set the name, data type, and default value for each of these.  Also note the column entitled Required: this allows me to specify whether the parameter value is optional (the default behavior) or required for package execution.  In this example, I have one parameter that is required, and the other is not. Let’s shift over to the parent package briefly, and demonstrate how to supply values to these parameters in the child package.  Using the execute package task, you can easily map variable values in the parent package to parameters in the child package. The execute package task in the parent package, shown above, has the variable vThisClient from the parent package mapped to the pClientID parameter shown earlier in the child package.  Note that there is no value mapped to the child package parameter named pOutputFolder.  Since this parameter has the Required property set to False, we don’t have to specify a value for it, which will cause that parameter to use the default value we supplied when designing the child pacakge. The last step in the parent package is to create the for each loop container I mentioned earlier, and place the execute package task inside it.  I’m using an object variable to store the distinct client ID values, and I use that as the iterator for the loop (I describe how to do this more in depth here).  For each iteration of the loop, a different client ID value will be passed into the child package parameter. The final step is to configure the child package to actually do something meaningful with the parameter values passed into it.  In this case, I’ve modified the OleDB source query to use the pClientID value in the WHERE clause of the query to restrict results for each iteration to a single client’s data.  Additionally, I’ll use both the pClientID and pOutputFolder parameters to dynamically build the output filename. As shown, the pClientID is used in the WHERE clause, so we only get the current client’s invoices for each iteration of the loop. For the flat file connection, I’m setting the Connection String property using an expression that engages both of the parameters for this package, as shown above. Parting Thoughts There are many uses for package parameters beyond a simple parent-child design pattern.  For example, you can create standalone packages (those not intended to be used as a child package) and still use parameters.  Parameter values may be supplied to a package directly at runtime by a SQL Server Agent job, through the command line (via dtexec.exe), or through T-SQL. Also, you can also have project parameters as well as package parameters.  Project parameters work in much the same way as package parameters, but the parameters apply to all packages in a project, not just a single package. Conclusion Of the numerous advantages of using catalog deployment model in SSIS 2012 and beyond, package parameters are near the top of the list.  Parameters allow you to easily share values from parent to child packages, enabling more dynamic behavior and better code encapsulation. If you want me to take a look at your server and its settings, or if your server is facing any issue we can Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Advanced donut caching: using dynamically loaded controls

  - by DigiMortal

  Yesterday I solved one caching problem with local community portal. I enabled output cache on SharePoint Server 2007 to make site faster. Although caching works fine I needed to do some additional work because there are some controls that show different content to different users. In this example I will show you how to use “donut caching” with user controls – powerful way to drive some content around cache. About donut caching Donut caching means that although you are caching your content you have some holes in it so you can still affect the output that goes to user. By example you can cache front page on your site and still show welcome message that contains correct user name. To get better idea about donut caching I suggest you to read ScottGu posting Tip/Trick: Implement "Donut Caching" with the ASP.NET 2.0 Output Cache Substitution Feature. Basically donut caching uses ASP.NET substitution control. In output this control is replaced by string you return from static method bound to substitution control. Again, take a look at ScottGu blog posting I referred above. Problem If you look at Scott’s example it is pretty plain and easy by its output. All it does is it writes out current user name as string. Here are examples of my login area for anonymous and authenticated users:    It is clear that outputting mark-up for these views as string is pretty lame to implement in code at string level. Every little change in design will end up with new version of controls library because some parts of design “live” there. Solution: using user controls I worked out easy solution to my problem. I used cache substitution and user controls together. I have three user controls: LogInControl – this is the proxy control that checks which “real” control to load. AnonymousLogInControl – template and logic for anonymous users login area. AuthenticatedLogInControl – template and logic for authenticated users login area. This is the control we render for each user separately because it contains user name and user profile fill percent. Anonymous control is not very interesting because it is only about keeping mark-up in separate file. Interesting parts are LogInControl and AuthenticatedLogInControl. Creating proxy control The first thing was to create control that has substitution area where “real” control is loaded. This proxy control should also be available to decide which control to load. The definition of control is very primitive. <%@ Control EnableViewState="false" Inherits="MyPortal.Profiles.LogInControl" %> <asp:Substitution runat="server" MethodName="ShowLogInBox" /> But code is a little bit tricky. Based on current user instance we decide which login control to load. Then we create page instance and load our control through it. When control is loaded we will call DataBind() method. In this method we evaluate all fields in loaded control (it was best choice as Load and other events will not be fired). Take a look at the code. public static string ShowLogInBox(HttpContext context) {     var user = SPContext.Current.Web.CurrentUser;     string controlName;       if (user != null)         controlName = "AuthenticatedLogInControl.ascx";     else         controlName = "AnonymousLogInControl.ascx";       var path = "~/_controltemplates/" + controlName;     var output = new StringBuilder(10000);       using(var page = new Page())     using(var ctl = page.LoadControl(path))     using(var writer = new StringWriter(output))     using(var htmlWriter = new HtmlTextWriter(writer))     {         ctl.DataBind();         ctl.RenderControl(htmlWriter);     }     return output.ToString(); } When control is bound to data we ask to render it its contents to StringBuilder. Now we have the output of control as string and we can return it from our method. Of course, notice how correct I am with resources disposing. :) The method that returns contents for substitution control is static method that has no connection with control instance because hen page is read from cache there are no instances of controls available. Conclusion As you saw it was not very hard to use donut caching with user controls. Instead of writing mark-up of controls to static method that is bound to substitution control we can still use our user controls.

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• User Experience Fundamentals

  - by ultan o'broin

  Understanding what user experience means in the modern work environment is central to building great-looking usable applications on the desktop or mobile devices. What better place to start a series of blog posts on such Applications User Experience team enablement for customers and partners than by sharing what the term really means, writes team member Karen Scipi. Applications UX have gained valuable insights into developing a user experience that reflects the experience of today’s worker. We have observed real workers performing real tasks in real work environments, and we have developed a set of new standards of application design that have been scientifically proven to be beneficial to enable today’s workers. We share such expertise to enable our customers and partners to benefit from our insights and to further their return on investment when building Oracle applications. So, What is User Experience? ?The user interface (UI) is about the on-screen user context provided by the layout of widgets (such as icons, fields, and buttons and more) and the visual impact of colors, typographic choices, and so on. The UI comprises the “look and feel” of the application that users interact with, and reflects, in essence, the most immediate aspects of usability we can now all relate to.  User experience, on the other hand, is about understanding the whole context of the world of work, how workers go about completing tasks, crossing all sorts of boundaries along the way. It is a study of how business processes and workers goals coincide, how users work with technology or other tools to get their jobs done, their interactions with other users, and their response to the technical, physical, and cultural environment around them. User experience is all about how users work—their work environments, office layouts, desk tools, types of devices, their working day, and more. Even their job aids, such as sticky notes, offer insight for UX innovation. User experience matters because businesses needs to be efficient, work must be productive, and users now demand to be satisfied by the applications they work with. In simple terms, tasks finished quickly and accurately for a business evokes organization and worker satisfaction, which in turn makes workers feel good and more than willing to use the application again tomorrow. Design Principles for the Enterprise Worker The consumerization of information technology has raised the bar for enterprise applications. Applications must be consistent, simple, intuitive, but above all contextual, reflecting how and when workers work, in the office or on the go. For example, the Google search experience with its type-ahead keyword-prompting feature is how workers expect to be able to discover enterprise information, too. Type-ahead in PeopleSoft 9.1 To build software that enables workers to be productive, our design principles meet modern work requirements about consistency, with well-organized, context-driven information, geared for a working world of discovery and collaboration. Our applications must also behave in a simple, web-like way just like Amazon, Google, and Apple products that workers use at home or on the go. Our user experience must also reflect workers’ needs for flexibility and well-loved enterprise practices such as using popular desktop tools like Microsoft Excel or Outlook as required. Building User Experience Productively The building blocks of Oracle Fusion Applications are the user experience design patterns. Based on the Oracle Fusion Middleware technology used to build Oracle Fusion Applications, the patterns are reusable solutions to common usability challenges that ADF developers typically face as they build applications, extensions, and integrations. Developers use the patterns as part of their Oracle toolkits to realize great usability consistently and in a productive way. Our design pattern creation process is informed by user experience research and science, an understanding of our technology’s capabilities, the demands for simplification and intuitiveness from users, and the best of Oracle’s acquisitions strategy (an injection of smart people and smart innovation). The patterns are supported by usage guidelines and are tested in our labs and assembled into a library of proven resources we used to build own Oracle Fusion Applications and other Oracle applications user experiences. The design patterns library is now available to the ADF community and to our partners and customers, for free. Developers with ADF skills and other technology skills can now offer more than just coding and functionality and still use the best in enterprise methodologies to ensure that a great user experience is easily applied, scaled, and maintained, whether it be for SaaS or on-premise deployments for Oracle Fusion Applications, for applications coexistence, or for partner integrations scenarios.  Oracle partners and customers already using our design patterns to build solutions and win business in smart and productive ways are now sharing their experiences and insights on pattern use to benefit your entire business. Applications UX is going global with the message and the means. Our hands-on user experience enablement through ADF  is expanding. So, stay tuned to Misha Vaughan's Voice of User Experience (VOX) blog and follow along on Twitter at @usableapps for news of outreach events and other learning opportunities. Interested in Learning More? Oracle Fusion Applications User Experience Patterns and Guidelines Library Shout-outs for Oracle UX Design Patterns Oracle Fusion Applications User Experience Design Patterns: Productivity Realized

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• DBCC CHECKDB (BatmanDb, REPAIR_ALLOW_DATA_LOSS) &ndash; Are you Feeling Lucky?

  - by David Totzke

  I’m currently working for a client on a PowerBuilder to WPF migration.  It’s one of those “I could tell you, but I’d have to kill you” kind of clients and the quick-lime pits are currently occupied by the EMC tech…but I’ve said too much already. At approximately 3 or 4 pm that day users of the Batman[1] application here in Gotham[1] started to experience problems accessing the application.  Batman[2] is a document management system here that also integrates with the ERP system.  Very little goes on here that doesn’t involve Batman in some way.  The errors being received seemed to point to network issues (TCP protocol error, connection forcibly closed by the remote host etc…) but the real issue was much more insidious. Connecting to the database via SSMS and performing selects on certain tables underlying the application areas that were having problems started to reveal the issue.  You couldn’t do a SELECT * FROM MyTable without it bombing and giving the same error noted above.  A run of DBCC CHECKDB revealed 14 tables with corruption.  One of the tables with issues was the Document table.  Pretty central to a “document management” system.  Information was obtained from IT that a single drive in the SAN went bad in the night.  A new drive was in place and was working fine.  The partition that held the Batman database is configured for RAID Level 5 so a single drive failure shouldn’t have caused any trouble and yet, the database is corrupted.  They do hourly incremental backups here so the first thing done was to try a restore.  A restore of the most recent backup failed so they worked backwards until they hit a good point.  This successful restore was for a backup at 3AM – a full day behind.  This time also roughly corresponds with the time the SAN started to report the drive failure.  The plot thickens… I got my hands on the output from DBCC CHECKDB and noticed a pattern.  What’s sad is that nobody that should have noticed the pattern in the DBCC output did notice.  There was a rush to do things to try and recover the data before anybody really understood what was wrong with it in the first place.  Cooler heads must prevail in these circumstances and some investigation should be done and a plan of action laid out or you could end up making things worse[3].  DBCC CHECKDB also told us that: repair_allow_data_loss is the minimum repair level for the errors found by DBCC CHECKDB Yikes.  That means that the database is so messed up that you’re definitely going to lose some stuff when you repair it to get it back to a consistent state.  All the more reason to do a little more investigation into the problem.  Rescuing this database is preferable to having to export all of the data possible from this database into a new one.  This is a fifteen year old application with about seven hundred tables.  There are TRIGGERS everywhere not to mention the referential integrity constraints to deal with.  Only fourteen of the tables have an issue.  We have a good backup that is missing the last 24 hours of business which means we could have a “do-over” of yesterday but that’s not a very palatable option either. All of the affected tables had TEXT columns and all of the errors were about LOB data types and orphaned off-row data which basically means TEXT, IMAGE or NTEXT columns.  If we did a SELECT on an affected table and excluded those columns, we got all of the rows.  We exported that data into a separate database.  Things are looking up.  Working on a copy of the production database we then ran DBCC CHECKDB with REPAIR_ALLOW_DATA_LOSS and that “fixed” everything up.   The allow data loss option will delete the bad rows.  This isn’t too horrible as we have all of those rows minus the text fields from out earlier export.  Now I could LEFT JOIN to the exported data to find the missing rows and INSERT them minus the TEXT column data. We had the restored data from the good 3AM backup that we could now JOIN to and, with fingers crossed, recover the missing TEXT column information.  We got lucky in that all of the affected rows were old and in the end we didn’t lose anything.  :O  All of the row counts along the way worked out and it looks like we dodged a major bullet here. We’ve heard back from EMC and it turns out the SAN firmware that they were running here is apparently buggy.  This thing is only a couple of months old.  Grrr…. They dispatched a technician that night to come and update it .  That explains why RAID didn’t save us. All-in-all this could have been a lot worse.  Given the root cause here, they basically won the lottery in not losing anything. Here are a few links to some helpful posts on the SQL Server Engine blog.  I love the title of the first one: Which part of 'REPAIR_ALLOW_DATA_LOSS' isn't clear? CHECKDB (Part 8): Can repair fix everything? (in fact, read the whole series) Ta da! Emergency mode repair (we didn’t have to resort to this one thank goodness)   Dave Just because I can…   [1] Names have been changed to protect the guilty. [2] I'm Batman. [3] And if I'm the coolest head in the room, you've got even bigger problems...

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• Use WLST to Delete All JMS Messages From a Destination

  - by james.bayer

  I got a question today about whether WebLogic Server has any tools to delete all messages from a JMS Queue.  It just so happens that the WLS Console has this capability already.  It’s available on the screen after the “Show Messages” button is clicked on a destination’s Monitoring tab as seen in the screen shot below. The console is great for something ad-hoc, but what if I want to automate this?  Well it just so happens that the console is just a weblogic application layered on top of the JMX Management interface.  If you look at the MBean Reference, you’ll find a JMSDestinationRuntimeMBean that includes the operation deleteMessages that takes a JMS Message Selector as an argument.  If you pass an empty string, that is essentially a wild card that matches all messages. Coding a stand-alone JMX client for this is kind of lame, so let’s do something more suitable to scripting.  In addition to the console, WebLogic Scripting Tool (WLST) based on Jython is another way to browse and invoke MBeans, so an equivalent interactive shell session to delete messages from a destination would looks like this: D:\Oracle\fmw11gr1ps3\user_projects\domains\hotspot_domain\bin>setDomainEnv.cmd D:\Oracle\fmw11gr1ps3\user_projects\domains\hotspot_domain>java weblogic.WLST   Initializing WebLogic Scripting Tool (WLST) ...   Welcome to WebLogic Server Administration Scripting Shell   Type help() for help on available commands   wls:/offline> connect('weblogic','welcome1','t3://localhost:7001') Connecting to t3://localhost:7001 with userid weblogic ... Successfully connected to Admin Server 'AdminServer' that belongs to domain 'hotspot_domain'.   Warning: An insecure protocol was used to connect to the server. To ensure on-the-wire security, the SSL port or Admin port should be used instead.   wls:/hotspot_domain/serverConfig> serverRuntime() Location changed to serverRuntime tree. This is a read-only tree with ServerRuntimeMBean as the root. For more help, use help(serverRuntime)   wls:/hotspot_domain/serverRuntime> cd('JMSRuntime/AdminServer.jms/JMSServers/JMSServer-0/Destinations/SystemModule-0!Queue-0') wls:/hotspot_domain/serverRuntime/JMSRuntime/AdminServer.jms/JMSServers/JMSServer-0/Destinations/SystemModule-0!Queue-0> ls() dr-- DurableSubscribers   -r-- BytesCurrentCount 0 -r-- BytesHighCount 174620 -r-- BytesPendingCount 0 -r-- BytesReceivedCount 253548 -r-- BytesThresholdTime 0 -r-- ConsumersCurrentCount 0 -r-- ConsumersHighCount 0 -r-- ConsumersTotalCount 0 -r-- ConsumptionPaused false -r-- ConsumptionPausedState Consumption-Enabled -r-- DestinationInfo javax.management.openmbean.CompositeDataSupport(compositeType=javax.management.openmbean.CompositeType(name=DestinationInfo,items=((itemName=ApplicationName,itemType=javax.management.openmbean.SimpleType(name=java.lang.String)),(itemName=ModuleName,itemType=javax.management.openmbean.SimpleType(name=java.lang.String)),(itemName openmbean.SimpleType(name=java.lang.Boolean)),(itemName=SerializedDestination,itemType=javax.management.openmbean.SimpleType(name=java.lang.String)),(itemName=ServerName,itemType=javax.management.openmbean.SimpleType(name=java.lang.String)),(itemName=Topic,itemType=javax.management.openmbean.SimpleType(name=java.lang.Boolean)),(itemName=VersionNumber,itemType=javax.management.op ule-0!Queue-0, Queue=true, SerializedDestination=rO0ABXNyACN3ZWJsb2dpYy5qbXMuY29tbW9uLkRlc3RpbmF0aW9uSW1wbFSmyJ1qZfv8DAAAeHB3kLZBABZTeXN0ZW1Nb2R1bGUtMCFRdWV1ZS0wAAtKTVNTZXJ2ZXItMAAOU3lzdGVtTW9kdWxlLTABAANBbGwCAlb6IS6T5qL/AAAACgEAC0FkbWluU2VydmVyAC2EGgJW+iEuk+ai/wAAAAsBAAtBZG1pblNlcnZlcgAthBoAAQAQX1dMU19BZG1pblNlcnZlcng=, ServerName=JMSServer-0, Topic=false, VersionNumber=1}) -r-- DestinationType Queue -r-- DurableSubscribers null -r-- InsertionPaused false -r-- InsertionPausedState Insertion-Enabled -r-- MessagesCurrentCount 0 -r-- MessagesDeletedCurrentCount 3 -r-- MessagesHighCount 2 -r-- MessagesMovedCurrentCount 0 -r-- MessagesPendingCount 0 -r-- MessagesReceivedCount 3 -r-- MessagesThresholdTime 0 -r-- Name SystemModule-0!Queue-0 -r-- Paused false -r-- ProductionPaused false -r-- ProductionPausedState Production-Enabled -r-- State advertised_in_cluster_jndi -r-- Type JMSDestinationRuntime   -r-x closeCursor Void : String(cursorHandle) -r-x deleteMessages Integer : String(selector) -r-x getCursorEndPosition Long : String(cursorHandle) -r-x getCursorSize Long : String(cursorHandle) -r-x getCursorStartPosition Long : String(cursorHandle) -r-x getItems javax.management.openmbean.CompositeData[] : String(cursorHandle),Long(start),Integer(count) -r-x getMessage javax.management.openmbean.CompositeData : String(cursorHandle),Long(messageHandle) -r-x getMessage javax.management.openmbean.CompositeData : String(cursorHandle),String(messageID) -r-x getMessage javax.management.openmbean.CompositeData : String(messageID) -r-x getMessages String : String(selector),Integer(timeout) -r-x getMessages String : String(selector),Integer(timeout),Integer(state) -r-x getNext javax.management.openmbean.CompositeData[] : String(cursorHandle),Integer(count) -r-x getPrevious javax.management.openmbean.CompositeData[] : String(cursorHandle),Integer(count) -r-x importMessages Void : javax.management.openmbean.CompositeData[],Boolean(replaceOnly) -r-x moveMessages Integer : String(java.lang.String),javax.management.openmbean.CompositeData,Integer(java.lang.Integer) -r-x moveMessages Integer : String(selector),javax.management.openmbean.CompositeData -r-x pause Void : -r-x pauseConsumption Void : -r-x pauseInsertion Void : -r-x pauseProduction Void : -r-x preDeregister Void : -r-x resume Void : -r-x resumeConsumption Void : -r-x resumeInsertion Void : -r-x resumeProduction Void : -r-x sort Long : String(cursorHandle),Long(start),String[](fields),Boolean[](ascending)   wls:/hotspot_domain/serverRuntime/JMSRuntime/AdminServer.jms/JMSServers/JMSServer-0/Destinations/SystemModule-0!Queue-0> cmo.deleteMessages('') 2 where the domain name is “hotspot_domain”, the JMS Server name is “JMSServer-0”, the Queue name is “Queue-0” and the System Module is named “SystemModule-0”.  To invoke the operation, I use the “cmo” object, which is the “Current Management Object” that represents the currently navigated to MBean.  The 2 indicates that two messages were deleted.  Combining this WLST code with a recent post by my colleague Steve that shows you how to use an encrypted file to store the authentication credentials, you could easily turn this into a secure automated script.  If you need help with that step, a long while back I blogged about some WLST basics.  Happy scripting.

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• Dynamic Bursting ... no really!

  - by Tim Dexter

  If any of you have seen me or my colleagues present BI Publisher to you then we have hopefully mentioned 'bursting.' You may have even seen a demo where we talk about being able to take a batch of data, say invoices. Then split them by some criteria, say customer id; format them with a template; generate the output and then deliver the documents to the recipients with a click. We and especially I, always say this can be completely dynamic! By this I mean, that you could store customer preferences in a database. What layout would each customer like; what output format they would like and how they would like the document delivered. We (I) talk a good talk, but typically don't do the walk in a demo. We hard code everything in the bursting query or bursting control file to get the concept across. But no more peeps! I have finally put together a dynamic bursting demo! Its been minutes in the making but its been tough to find those minutes! Read on ... It's nothing amazing in terms of making the burst dynamic. I created a CUSTOMER_PREFS table with some simple UI in an APEX application so that I can maintain their requirements. In EBS you have descriptive flexfields that could do the same thing or probably even 'contact' fields to store most of the info. Here's my table structure: Name                           Type ------------------------------ -------- CUSTOMER_ID                    NUMBER(6) TEMPLATE_TYPE                  VARCHAR2(20) TEMPLATE_NAME                  VARCHAR2(120) OUTPUT_FORMAT                  VARCHAR2(20) DELIVERY_CHANNEL               VARCHAR2(50) EMAIL                          VARCHAR2(255) FAX                            VARCHAR2(20) ATTACH                         VARCHAR2(20) FILE_LOC                       VARCHAR2(255) Simple enough right? Just need CUSTOMER_ID as the key for the bursting engine to join it to the customer data at burst time. I have not covered the full delivery options, just email, fax and file location. Remember, its a demo people :0) However the principal is exactly the same for each delivery type. They each have a set of attributes that need to be provided and you will need to handle that in your bursting query. On a side note, in EBS, you use a bursting control file, you can apply the same principals that I'm laying out here you just need to get the customer bursting info into the XML data stream so that you can refer to it in the control file using XPATH expressions. Next, we need to look up what attributes or parameters are required for each delivery method. that can be found in the documentation here.  Now we know the combinations of parameters and delivery methods we can construct the query using a series a decode statements: select distinct cp.customer_id "KEY", cp.template_name TEMPLATE, cp.template_type TEMPLATE_FORMAT, 'en-US' LOCALE, cp.output_format OUTPUT_FORMAT, 'false' SAVE_FORMAT, cp.delivery_channel DEL_CHANNEL, decode(cp.delivery_channel,'FILE', cp.file_loc , 'EMAIL', cp.email , 'FAX', cp.fax) PARAMETER1, decode(cp.delivery_channel,'FILE', c.cust_last_name||'_orders.pdf' ,'EMAIL','[email protected]' ,'FAX', 'faxserver.com') PARAMETER2, decode(cp.delivery_channel,'FILE',NULL ,'EMAIL','[email protected]' ,'FAX', null) PARAMETER3, decode(cp.delivery_channel,'FILE',NULL ,'EMAIL','Your current orders' ,'FAX',NULL) PARAMETER4, decode(cp.delivery_channel,'FILE',NULL ,'EMAIL','Please find attached a copy of your current orders with BI Publisher, Inc' ,'FAX',NULL) PARAMETER5, decode(cp.delivery_channel,'FILE',NULL ,'EMAIL','false' ,'FAX',NULL) PARAMETER6, decode(cp.delivery_channel,'FILE',NULL ,'EMAIL','[email protected]' ,'FAX',NULL) PARAMETER7 from cust_prefs cp, customers c, orders_view ov where cp.customer_id = c.customer_id and cp.customer_id = ov.customer_id order by cp.customer_id Pretty straightforward, just need to test, test, test, the query and ensure it's bringing back the correct data based on each customers preferences. Notice the NULL values for parameters that are not relevant for a given delivery channel. You should end up with bursting control data that the bursting engine can use:  Now, your users can run the burst and documents will be formatted, generated and delivered based on the customer prefs. If you're interested in the example, I have used the sample OE schema data for the base report. The report files and CUST_PREFS table are zipped up here. The zip contains the data model (.xdmz), the report and templates (.xdoz) and the sql scripts to create and load data to the CUST_PREFS table.  Once you load the report into the catalog, you'll need to create the OE data connection and point the data model at it. You'll probably need to re-point the report to the data model too. Happy Bursting!

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• Oracle Social Network Developer Challenge: Bezzotech

  - by Kellsey Ruppel

  Originally posted by Jake Kuramoto on The Apps Lab blog. I’ve covered all the entries we had for the Oracle Social Network Developer Challenge, the winners, Dimitri and Martin, HarQen, TEAM Informatics and John Sim from Fishbowl Solutions, and today, I’m giving you bonus coverage. Friend of the ‘Lab, Bex Huff (@bex) from Bezzotech (@bezzotech), had an interesting OpenWorld. He rebounded from an allergic reaction to finish his entry, Honey Badger, only to have his other OpenWorld commitments make him unable to present his work. Still, he did a bunch of work, and I want to make sure everyone knows about the Honey Badger. If you’re wondering about the name, it’s a meme; “honey badger don’t care.” Bex tackled a common problem with social tools by adding game mechanics to create an incentive for people to keep their profiles updated. He used a Hot-or-Not style comparison app that poses expertise questions and awards a badge to the winner. Questions are based on whatever attributes the business wants to emphasize. The goal is to find the mavens in an organization, give them praise and recognition, ideally creating incentive for everyone to raise their games. In his own words: There is a real information quality problem in social networks. In last year’s keynote, Larry Elison demonstrated how to use the social network to track down resources that have the skill sets needed for specific projects. But how well would that work in real life? People usually update that information with the basic profile information, but they rarely update their profiles with latest news items, projects, customers, or skills. It’s a pain. Or, put another way, when was the last time you updated your LinkedIn profile? Enter the Honey Badger! This is a example of a comparator app that gamifies the way people keep their profiles updated, which ensures higher quality data in the social network. An administrator comes up with a series of important questions: Who is a better communicator? Who is a better Java programmer? Who is a better team player? And people would have a space in their profile to give a justification as to why they have these skills. The second part of the app is the comparator. It randomly shows two people, their names, and their justification for why they have these skills. You will click on one of them to “vote” for them, then on the next page you will see the results from the previous match, and get 2 new people to vote on. Anybody with a winning score wins a “Honey Badge” to be displayed on their profile page, which proudly states that their peers agree that this person has those skills. Once a badge is won, it will be jealously guarded. The longer your go without updating your profile, the more likely it is that you will lose your badge. This “loss aversion” is well known in psychology, and is a strong incentive for people to keep their profiles up to date. If a user sees their rank drop from 90% to 60%, they will find the time to update their justification! Unfortunately, during the hackathon we were not allowed to modify the schema to allow for additional fields such as “justification.” So this hack is limited to just the one basic question: who is the bigger Honey Badger? Here are some shots of the Honey Badger application: #gallery-1 { margin: auto; } #gallery-1 .gallery-item { float: left; margin-top: 10px; text-align: center; width: 33%; } #gallery-1 img { border: 2px solid #cfcfcf; } #gallery-1 .gallery-caption { margin-left: 0; } Thanks to Bex and everyone for participating in our challenge. Despite very little time to promote this event, we had a great turnout and creative and useful entries. The amount of work required to put together these final entries was significant, especially during a conference, and the judges and all of us involved were impressed at how much work everyone was able to do. Congrats to everyone, pat yourselves on the back. Stay tuned if you’re interested in challenges like these. We’ll likely be running similar events in the not-so-distant future.

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• Man pages not finding entry

  - by Mike

  So, I'm not sure what is going on with my system (ubuntu 12.04), but my man pages do not seem to be working. I try man gcc and get the following response No manual entry for gcc See 'man 7 undocumented' for help when manual pages are not available. However I see the man entry in /usr/share/man/man1/gcc.1.gz Here is what my /etc/manpath.config file looks like # manpath.config # # This file is used by the man-db package to configure the man and cat paths. # It is also used to provide a manpath for those without one by examining # their PATH environment variable. For details see the manpath(5) man page. # # Lines beginning with `#' are comments and are ignored. Any combination of # tabs or spaces may be used as `whitespace' separators. # # There are three mappings allowed in this file: # -------------------------------------------------------- # MANDATORY_MANPATH manpath_element # MANPATH_MAP path_element manpath_element # MANDB_MAP global_manpath [relative_catpath] #--------------------------------------------------------- # every automatically generated MANPATH includes these fields # #MANDATORY_MANPATH /usr/src/pvm3/man # MANDATORY_MANPATH /usr/man MANDATORY_MANPATH /usr/share/man MANDATORY_MANPATH /usr/local/share/man #--------------------------------------------------------- # set up PATH to MANPATH mapping # ie. what man tree holds man pages for what binary directory. # # *PATH* -> *MANPATH* # MANPATH_MAP /bin /usr/share/man MANPATH_MAP /usr/bin /usr/share/man MANPATH_MAP /sbin /usr/share/man MANPATH_MAP /usr/sbin /usr/share/man MANPATH_MAP /usr/local/bin /usr/local/man MANPATH_MAP /usr/local/bin /usr/local/share/man MANPATH_MAP /usr/local/sbin /usr/local/man MANPATH_MAP /usr/local/sbin /usr/local/share/man MANPATH_MAP /usr/X11R6/bin /usr/X11R6/man MANPATH_MAP /usr/bin/X11 /usr/X11R6/man MANPATH_MAP /usr/games /usr/share/man MANPATH_MAP /opt/bin /opt/man MANPATH_MAP /opt/sbin /opt/man #--------------------------------------------------------- # For a manpath element to be treated as a system manpath (as most of those # above should normally be), it must be mentioned below. Each line may have # an optional extra string indicating the catpath associated with the # manpath. If no catpath string is used, the catpath will default to the # given manpath. # # You *must* provide all system manpaths, including manpaths for alternate # operating systems, locale specific manpaths, and combinations of both, if # they exist, otherwise the permissions of the user running man/mandb will # be used to manipulate the manual pages. Also, mandb will not initialise # the database cache for any manpaths not mentioned below unless explicitly # requested to do so. # # In a per-user configuration file, this directive only controls the # location of catpaths and the creation of database caches; it has no effect # on privileges. # # Any manpaths that are subdirectories of other manpaths must be mentioned # *before* the containing manpath. E.g. /usr/man/preformat must be listed # before /usr/man. # # *MANPATH* -> *CATPATH* # MANDB_MAP /usr/man /var/cache/man/fsstnd MANDB_MAP /usr/share/man /var/cache/man MANDB_MAP /usr/local/man /var/cache/man/oldlocal MANDB_MAP /usr/local/share/man /var/cache/man/local MANDB_MAP /usr/X11R6/man /var/cache/man/X11R6 MANDB_MAP /opt/man /var/cache/man/opt # #--------------------------------------------------------- # Program definitions. These are commented out by default as the value # of the definition is already the default. To change: uncomment a # definition and modify it. # #DEFINE pager pager -s #DEFINE cat cat #DEFINE tr tr '\255\267\264\327' '\055\157\047\170' #DEFINE grep grep #DEFINE troff groff -mandoc #DEFINE nroff nroff -mandoc #DEFINE eqn eqn #DEFINE neqn neqn #DEFINE tbl tbl #DEFINE col col #DEFINE vgrind vgrind #DEFINE refer refer #DEFINE grap grap #DEFINE pic pic -S # #DEFINE compressor gzip -c7 #--------------------------------------------------------- # Misc definitions: same as program definitions above. # #DEFINE whatis_grep_flags -i #DEFINE apropos_grep_flags -iEw #DEFINE apropos_regex_grep_flags -iE #--------------------------------------------------------- # Section names. Manual sections will be searched in the order listed here; # the default is 1, n, l, 8, 3, 0, 2, 5, 4, 9, 6, 7. Multiple SECTION # directives may be given for clarity, and will be concatenated together in # the expected way. # If a particular extension is not in this list (say, 1mh), it will be # displayed with the rest of the section it belongs to. The effect of this # is that you only need to explicitly list extensions if you want to force a # particular order. Sections with extensions should usually be adjacent to # their main section (e.g. "1 1mh 8 ..."). # SECTION 1 n l 8 3 2 3posix 3pm 3perl 5 4 9 6 7 # #--------------------------------------------------------- # Range of terminal widths permitted when displaying cat pages. If the # terminal falls outside this range, cat pages will not be created (if # missing) or displayed. # #MINCATWIDTH 80 #MAXCATWIDTH 80 # # If CATWIDTH is set to a non-zero number, cat pages will always be # formatted for a terminal of the given width, regardless of the width of # the terminal actually being used. This should generally be within the # range set by MINCATWIDTH and MAXCATWIDTH. # #CATWIDTH 0 # #--------------------------------------------------------- # Flags. # NOCACHE keeps man from creating cat pages. #NOCACHE Thanks for any help (p.s. even 'man man' fails) Edit: When I run ls -l /usr/share/man/man1/gcc* I get the following output lrwxrwxrwx 1 root root 12 May 27 15:41 /usr/share/man/man1/gcc.1.gz -> gcc-4.6.1.gz -rw-r--r-- 1 root root 217776 Apr 15 17:34 /usr/share/man/man1/gcc-4.6.1.gz

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• Execute TSQL statement with ExecuteStoreQuery in entity framework 4.0

  - by Jalpesh P. Vadgama

  I was playing with entity framework in recent days and I was searching something that how we can execute TSQL statement in entity framework. And I have found one great way to do that with entity framework ‘ExecuteStoreQuery’ method. It’s executes a TSQL statement against data source given enity framework context and returns strongly typed result. You can find more information about ExcuteStoreQuery from following link. http://msdn.microsoft.com/en-us/library/dd487208.aspx So let’s examine how it works. So Let’s first create a table against which we are going to execute TSQL statement. So I have added a SQL Express database as following. Now once we are done with adding a database let’s add a table called Client like following. Here you can see above Client table is very simple. There are only two fields ClientId and ClientName where ClientId is primary key and ClientName is field where we are going to store client name. Now it’s time to add some data to the table. So I have added some test data like following. Now it’s time to add entity framework model class. So right click project->Add new item and select ADO.NET entity model as following. After clicking on add button a wizard will start it will ask whether we need to create model classes from database or not but we already have our client table ready so I have selected generate from database as following. Once you process further in wizard it will be presented a screen where we can select the our table like following. Now once you click finish it will create model classes with for us. Now we need a gridview control where we need to display those data. So in Default.aspx page I have added a grid control like following. <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="EntityFramework._Default" %> <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> </asp:Content> <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> <h2> Welcome to ASP.NET! </h2> <p> To learn more about ASP.NET visit <a href="http://www.asp.net" title="ASP.NET Website">www.asp.net</a>. </p> <p> You can also find <a href="http://go.microsoft.com/fwlink/?LinkID=152368&amp;clcid=0x409" title="MSDN ASP.NET Docs">documentation on ASP.NET at MSDN</a>. <asp:GridView ID="grdClient" runat="server"> </asp:GridView> </p> </asp:Content> Now once we are done with adding Gridview its time to write code for server side. So I have written following code in Page_load event of default.aspx page. protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { using (var context = new EntityFramework.TestEntities()) { ObjectResult<Client> result = context.ExecuteStoreQuery<Client>("Select * from Client"); grdClient.DataSource = result; grdClient.DataBind(); } } } Here in the above code you can see that I have written create a object of our entity model and then with the help of the ExecuteStoreQuery method I have execute a simple select TSQL statement which will return a object result. I have bind that object result with gridview to display data. So now we are done with coding.So let’s run application in browser. Following is output as expected. That’s it. Hope you like it. Stay tuned for more..Till then happy programming.

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• Trigger Happy

  - by Tim Dexter

  Its been a while, I know, we’ll say no more OK? I’ll just write …In the latest BIP 11.1.1.6 release and if I’m really honest; the release before this (we'll call it dot 5 for brevity.) The boys and gals in the engine room have been real busy enhancing BIP with some new functionality. Those of you that use the scheduling engine in OBIEE may already know and use the ‘conditional scheduling’ feature. This allows you to be more intelligent about what reports get run and sent to folks on a scheduled basis. You create a ‘trigger’ analysis (answer) that is executed at schedule time prior to the main report. When the schedule rolls around, the trigger is run, if it returns rows, then the main report is run and delivered. If there are no rows returned, then the main report is not run. Useful right? Your users are not bombarded with 20 reports in their inbox every week that they need to wade throu. They get a handful that they know they need to look at. If you ensure you use conditional formatting in the report then they can find the anomalous data in the reports very quickly and move on to the rest of their day more quickly. You could even think of OBIEE as a virtual team member, scouring the data on your behalf 24/7 and letting you know when its found an issue.BI Publisher, wanting the team t-shirt and the khaki pants, has followed suit. You can now set up ‘triggers’ for it to execute before it runs the main report. Just like its big brother, if the scheduled report trigger returns rows of data; it then executes the main report. Otherwise, the report is skipped until the next schedule time rolls around. Sound familiar?BIP differs a little, in that you only need to construct a query to act as the trigger rather than a complete report. Let assume we have a monthly wage by department report on a schedule. We only want to send the report to managers if their departmental wages reach and/or exceed a certain amount. The toughest part about this is coming up with the SQL to test the business rule you want to implement. For my example, its not that tough: select d.department_name, sum(e.salary) as wage_total from employees e, departments d where d.department_id = e.department_id group by d.department_name having sum(e.salary) > 230000 We're looking for departments where the wage cost is greater than 230,000 Dexter Dollars! With a bit of messing I found out you can parametrize the query. Users can then set a value at schedule time if they need to. To create the trigger is straightforward enough. You can create multiple triggers for users to select at schedule time. Notice I also used a parameter in the query, :wamount. Note the matching parameter in the tree on the left. You also dont need to return multiple columns, one is fine, the key is if there are rows returned. You can build the rest of your report as usual. At scheduling time the Schedule tab has a bit more on it. If your users want to set the trigger, they check the Use Trigger box. The page will then pop fields to pick the appropriate trigger they want to use, even a trigger on another data model if needed. Note it will also ask for the parameter value associated with the trigger. At this point you should note that the data model does not make a distinction between trigger and data model (extract) parameters. So users will see the parameters on the General and Schedule tabs. If per chance you do need to just have a trigger parameters. You can just hide them from the report using the Parameters popup in the report designer, just un-check the 'Show' box I have tested the opposite case where you do not want main report parameters seen in the trigger section. BIP handles that for you! Once the report hits its allotted schedule time, the trigger is executed. Based on the results the report will either run or be 'skipped.' Now, you have a smarter scheduler that will only deliver reports when folks need to see them and take action on the contents. More official info here for developers and here for users.

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• C# async and actors

  - by Alex.Davies

  If you read my last post about async, you might be wondering what drove me to write such odd code in the first place. The short answer is that .NET Demon is written using NAct Actors. Actors are an old idea, which I believe deserve a renaissance under C# 5. The idea is to isolate each stateful object so that only one thread has access to its state at any point in time. That much should be familiar, it's equivalent to traditional lock-based synchronization. The different part is that actors pass "messages" to each other rather than calling a method and waiting for it to return. By doing that, each thread can only ever be holding one lock. This completely eliminates deadlocks, my least favourite concurrency problem. Most people who use actors take this quite literally, and there are plenty of frameworks which help you to create message classes and loops which can receive the messages, inspect what type of message they are, and process them accordingly. But I write C# for a reason. Do I really have to choose between using actors and everything I love about object orientation in C#? Type safety Interfaces Inheritance Generics As it turns out, no. You don't need to choose between messages and method calls. A method call makes a perfectly good message, as long as you don't wait for it to return. This is where asynchonous methods come in. I have used NAct for a while to wrap my objects in a proxy layer. As long as I followed the rule that methods must always return void, NAct queued up the call for later, and immediately released my thread. When I needed to get information out of other actors, I could use EventHandlers and callbacks (continuation passing style, for any CS geeks reading), and NAct would call me back in my isolated thread without blocking the actor that raised the event. Using callbacks looks horrible though. To remind you: m_BuildControl.FilterEnabledForBuilding(    projects,    enabledProjects = m_OutOfDateProjectFinder.FilterNeedsBuilding(        enabledProjects,             newDirtyProjects =             {                 ....... Which is why I'm really happy that NAct now supports async methods. Now, methods are allowed to return Task rather than just void. I can await those methods, and C# 5 will turn the rest of my method into a continuation for me. NAct will run the other method in the other actor's context, but will make sure that when my method resumes, we're back in my context. Neither actor was ever blocked waiting for the other one. Apart from when they were actually busy doing something, they were responsive to concurrent messages from other sources. To be fair, you could use async methods with lock statements to achieve exactly the same thing, but it's ugly. Here's a realistic example of an object that has a queue of data that gets passed to another object to be processed: class QueueProcessor {    private readonly ItemProcessor m_ItemProcessor = ...     private readonly object m_Sync = new object();    private Queue<object> m_DataQueue = ...    private List<object> m_Results = ...     public async Task ProcessOne() {         object data = null;         lock (m_Sync)         {             data = m_DataQueue.Dequeue();         }         var processedData = await m_ItemProcessor.ProcessData(data); lock (m_Sync)         {             m_Results.Add(processedData);         }     } } We needed to write two lock blocks, one to get the data to process, one to store the result. The worrying part is how easily we could have forgotten one of the locks. Compare that to the version using NAct: class QueueProcessorActor : IActor { private readonly ItemProcessor m_ItemProcessor = ... private Queue<object> m_DataQueue = ... private List<object> m_Results = ... public async Task ProcessOne()     {         // We are an actor, it's always thread-safe to access our private fields         var data = m_DataQueue.Dequeue();         var processedData = await m_ItemProcessor.ProcessData(data);         m_Results.Add(processedData);     } } You don't have to explicitly lock anywhere, NAct ensures that your code will only ever run on one thread, because it's an actor. Either way, async is definitely better than traditional synchronous code. Here's a diagram of what a typical synchronous implementation might do: The left side shows what is running on the thread that has the lock required to access the QueueProcessor's data. The red section is where that lock is held, but doesn't need to be. Contrast that with the async version we wrote above: Here, the lock is released in the middle. The QueueProcessor is free to do something else. Most importantly, even if the ItemProcessor sometimes calls the QueueProcessor, they can never deadlock waiting for each other. So I thoroughly recommend you use async for all code that has to wait a while for things. And if you find yourself writing lots of lock statements, think about using actors as well. Using actors and async together really takes the misery out of concurrent programming.

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• JDK bug migration: components and subcomponents

  - by darcy

  One subtask of the JDK migration from the legacy bug tracking system to JIRA was reclassifying bugs from a three-level taxonomy in the legacy system, (product, category, subcategory), to a fundamentally two-level scheme in our customized JIRA instance, (component, subcomponent). In the JDK JIRA system, there is technically a third project-level classification, but by design a large majority of JDK-related bugs were migrated into a single "JDK" project. In the end, over 450 legacy subcategories were simplified into about 120 subcomponents in JIRA. The 120 subcomponents are distributed among 17 components. A rule of thumb used was that a subcategory had to have at least 50 bugs in it for it to be retained. Below is a listing the component / subcomponent classification of the JDK JIRA project along with some notes and guidance on which OpenJDK email addresses cover different areas. Eventually, a separate incidents project to host new issues filed at bugs.sun.com will use a slightly simplified version of this scheme. The preponderance of bugs and subcomponents for the JDK are in library-related areas, with components named foo-libs and subcomponents primarily named after packages. While there was an overall condensation of subcomponents in the migration, in some cases long-standing informal divisions in core libraries based on naming conventions in the description were promoted to formal subcomponents. For example, hundreds of bugs in the java.util subcomponent whose descriptions started with "(coll)" were moved into java.util:collections. Likewise, java.lang bugs starting with "(reflect)" and "(proxy)" were moved into java.lang:reflect. client-libs (Predominantly discussed on 2d-dev and awt-dev and swing-dev.) 2d demo java.awt java.awt:i18n java.beans (See beans-dev.) javax.accessibility javax.imageio javax.sound (See sound-dev.) javax.swing core-libs (See core-libs-dev.) java.io java.io:serialization java.lang java.lang.invoke java.lang:class_loading java.lang:reflect java.math java.net java.nio (Discussed on nio-dev.) java.nio.charsets java.rmi java.sql java.sql:bridge java.text java.util java.util.concurrent java.util.jar java.util.logging java.util.regex java.util:collections java.util:i18n javax.annotation.processing javax.lang.model javax.naming (JNDI) javax.script javax.script:javascript javax.sql org.openjdk.jigsaw (See jigsaw-dev.) security-libs (See security-dev.) java.security javax.crypto (JCE: includes SunJCE/MSCAPI/UCRYPTO/ECC) javax.crypto:pkcs11 (JCE: PKCS11 only) javax.net.ssl (JSSE, includes javax.security.cert) javax.security javax.smartcardio javax.xml.crypto org.ietf.jgss org.ietf.jgss:krb5 other-libs corba corba:idl corba:orb corba:rmi-iiop javadb other (When no other subcomponent is more appropriate; use judiciously.) Most of the subcomponents in the xml component are related to jaxp. xml jax-ws jaxb javax.xml.parsers (JAXP) javax.xml.stream (JAXP) javax.xml.transform (JAXP) javax.xml.validation (JAXP) javax.xml.xpath (JAXP) jaxp (JAXP) org.w3c.dom (JAXP) org.xml.sax (JAXP) For OpenJDK, most JVM-related bugs are connected to the HotSpot Java virtual machine. hotspot (See hotspot-dev.) build compiler (See hotspot-compiler-dev.) gc (garbage collection, see hotspot-gc-dev.) jfr (Java Flight Recorder) jni (Java Native Interface) jvmti (JVM Tool Interface) mvm (Multi-Tasking Virtual Machine) runtime (See hotspot-runtime-dev.) svc (Servicability) test core-svc (See serviceability-dev.) debugger java.lang.instrument java.lang.management javax.management tools The full JDK bug database contains entries related to legacy virtual machines that predate HotSpot as well as retired APIs. vm-legacy jit (Sun Exact VM) jit_symantec (Symantec VM, before Exact VM) jvmdi (JVM Debug Interface ) jvmpi (JVM Profiler Interface ) runtime (Exact VM Runtime) Notable command line tools in the $JDK/bin directory have corresponding subcomponents. tools appletviewer apt (See compiler-dev.) hprof jar javac (See compiler-dev.) javadoc(tool) (See compiler-dev.) javah (See compiler-dev.) javap (See compiler-dev.) jconsole launcher updaters (Timezone updaters, etc.) visualvm Some aspects of JDK infrastructure directly affect JDK Hg repositories, but other do not. infrastructure build (See build-dev and build-infra-dev.) licensing (Covers updates to the third party readme, licenses, and similar files.) release_eng (Release engineering) staging (Staging of web pages related to JDK releases.) The specification subcomponent encompasses the formal language and virtual machine specifications. specification language (The Java Language Specification) vm (The Java Virtual Machine Specification) The code for the deploy and install areas is not currently included in OpenJDK. deploy deployment_toolkit plugin webstart install auto_update install servicetags In the JDK, there are a number of cross-cutting concerns whose organization is essentially orthogonal to other areas. Since these areas generally have dedicated teams working on them, it is easier to find bugs of interest if these bugs are grouped first by their cross-cutting component rather than by the affected technology. docs doclet guides hotspot release_notes tools tutorial embedded build hotspot libraries globalization locale-data translation performance hotspot libraries The list of subcomponents will no doubt grow over time, but my inclination is to resist that growth since the addition of each subcomponent makes the system as a whole more complicated and harder to use. When the system gets closer to being externalized, I plan to post more blog entries describing recommended use of various custom fields in the JDK project.

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• MSCC: Career & IT Fair 2014

  Already a couple of weeks ago, I've been addressed by Ibraahim and Yunus to see whether it would be interesting to participate in the 1st Career & IT Fair organised by the UoM Computer Club. Well, luckily we met at the Global Windows Azure Bootcamp and I wasn't too sure whether it would be possible for me to attend after all. The main reason is given because of work demand and furthermore due to the fact that the Mauritius Software Craftsmanship Community currently has no advertising material at all. Here's the brief statement of the event: "The UOM Students' Computer Club in collaboration with the UOM Students' Union and UOM CSE Department is organising a 'Career & IT Fair' on the 23rd and 24th April 2014. This event has for objective to provide a platform to tertiary students, secondary students as well as vocational students, the opportunity to meet job recruiters." Luckily, I was reminded that the 23rd is a Wednesday, and therefore I decided that it might be interesting to move our weekly Code & Coffee session to the university and hence be able to attend the career fair. As it turned out it was a great choice and thankfully Pritvi, Nadim as well as Ishwon volunteered to be around at the "community booth". Thankfully, the computer club gave us - the MSCC and the LUGM - one of their spaces in the lobby area of the Paul Octave Wiéhé Auditorium. My impression about the event Very well and professionally organised. Seriously, the lads over at the UoM Computer Club did a great job in organising their 2 days event, and felt very comfortable at any time. Actually, it was kind of amusing to some of the members constantly running around and checking everything. Even though that the whole process went smooth and easy off the hand. There were a couple of interesting pieces of information and announcements during the opening ceremony. For example, the Computer Science faculty is a very young one and has been initiated back in 1988 only - just by 4 staff members at that time. Now, after 25 years they have achieved quite a lot and there are currently 1.000+ active students attending the numerous lectures and courses. But there is no room to rest on previous achievements, and I was kind of surprised to hear that there are plans to extend the campus, and offer new lectures in the fields of nanotechnology, big data handling, and - crossing fingers - the introduction and establishment of a space control centre. Mauritius is already part of the Square Kilometre Array (SKA) and hopefully there will be more activities into that direction in the near future. Community - Awareness and collaboration As stated earlier, I could only spent one morning but luckily other members of the MSCC and the LUGM stayed during the whole two days and provided answers to any interested person. As for me, I took the opportunity to get in touch with the other companies in the lobby. Mainly, to create some awareness about our IT communities but also to see whether there might be options for future engagement in common activities, too. So far, I was able to speak to representatives of the following companies: ACCA Mauritius Business at Work Infomil LinkByNet Microsoft Indian Ocean Islands & French Pacific Spherinity Training Institute Spoon Consulting Ltd. State Informatics Ltd. Unfortunately, I only had a quick chat with an HR representative of LinkByNet but I fully count on our MSCC members like Nitin or LUGM member Ronny to spread our intentions over there.  So far, all of the representatives were really interested in our concepts and activities and I'm currently catching up with an introduction flyer for the MSCC that I'm going to send out to all those contacts via mail. It would be great to have more craftsmen as well as professional support on board. Some pictures from the event MSCC: Fantastic outlook for the near future. Announcements were made on Big data, nanotechnology, and space control centre in Mauritius. Interesting! MSCC: The lobby area was cramped with students. Great way to exchange and network. Good luck to all candidates! Passing the relay staff to... I recommend you to continue to read about the first Career & IT Fair on Ish's blog. He has a great summary and more details on those two days of IT activities than I have. Thanks and feel free to leave a comment (or two)... 

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• How to make creating viewmodels at runtime less painful

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painful. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genius since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use a DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an in-depth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• Come meet our Interns in Dublin

  - by klaudia.drulis

  Oracle Worldwide Product Translation Group (WPTG) provides solutions for all Oracle product and Content translation requirements. WPTG is a global organisation with its headquarters in Ireland and employees in Oracle offices worldwide. WPTG offer expertise in fields such as process engineering, tools development, linguistic quality, terminology, global product release, financial and vendor management. WPTG provides translation solution for over 40 languages including Asia Pacific, European, American and Middle Eastern languages. WPTG first introduced an intern program over 10 years ago and it has become a key component of our teams structure. The majority of Interns are sourced from a Computer Science related course, these Interns joining the engineering team. Others are sourced from Business courses and work within the Business / Project management area. The intern program allows us to maintain ties with current course curriculum and brings fresh energy and perspective into our Organisation. Four of the full time staff working in Dublin today joined us originally as Interns and subsequently were offered permanent positions. Come Meet some of our 2010 Interns, Come and see what Darragh, Anthony, Caoimhe, James and Artemij thought about working within the WPTG at Oracle: Darragh “Oracle has been a fun, challenging work placement for me. From day one I was treated as a full member of staff, this was both comforting and a little bit scary. The responsibilities stack up but I found I was able to keep on top of everything and even make improvements to how we handle a few things thanks to a great team and a very supportive manager. There’s a very positive atmosphere in work that’s really conducive to getting a lot of work done. Ideas seem to be the central hub in my line of business so all of my ideas and innovations were greeted with enthusiasm. Oracle has given me a fantastic opportunity and I urge you to grab it with both hands, you’ll find that you’re with a set of like minded people from all works of life that make work both interesting and fun. Even when the pressure is on you know that you can always get help and advice from someone nearby. My last word of advice is don’t be afraid to stick your neck out, everyone here is willing to learn, try something new and innovate, your voice will be heard and who knows, you could end up having a large impact on Oracle and your career.” Anthony “I had a great experience working with Oracle, from day one I was treated like a full member of staff with responsibilities of my own. I found that the more I put into the work the more I got out from the experience. Volunteering and being willing to face challenges have made this a more exciting placement. I am given a lot of leeway to do my own projects and so I’ve found that I am really enjoying my time here.” Caoimhe “I am currently spending my year of placement within the Release Management Team in the WPTG. My main role is to handle the finance process of all translation projects under 100k which includes creating workspecs and PO's, sending out kits, dealing with vendor queries and handling the invoicing and payment part. I am really enjoying my time here at Oracle, everyone is very open and friendly and willing to help you out with any questions you may have. I would definitely be interested in returning to Oracle after I graduate!” James “I am currently on a 12 month placement with Oracle, working as part of the Worldwide Product Translation Group in the Business Management. The Business Management team provides a global view on WPTG’s vendor and business strategy and is an interface into WPTG for new business. The business management team work together to support the external translation partner network. My role is to support the Business Management team and also to work on various projects when the need arises. This involves working with translation vendors and working with other Oracle employees worldwide. I am really enjoying my time working for Oracle, at times it can be challenging bit also very rewarding. I would recommend any student wanting to undertake a placement year to apply to Oracle, I made some great friends and I will never forget my time in Dublin.” Artemij “From working within Oracle, I have truly understood what "career path" is, and what opportunities a large corporation like Oracle can offer. Without any illusions, the work itself is exciting, sometimes challenging, tests your ability to handle pressure, to make decisions and take responsibility, to learn quickly and cooperate efficiently in order to solve a problem. I have learned a lot about myself. What I am good at, where and what I can do better. My placement at Oracle has allowed me to get a clearer picture of what I want, and which door I am going to open after college. If you have any questions related to this article feel free to contact  [email protected].  You can find our job opportunities via http://campus.oracle.com

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• Anatomy of a .NET Assembly - CLR metadata 2

  - by Simon Cooper

  Before we look any further at the CLR metadata, we need a quick diversion to understand how the metadata is actually stored. Encoding table information As an example, we'll have a look at a row in the TypeDef table. According to the spec, each TypeDef consists of the following: Flags specifying various properties of the class, including visibility. The name of the type. The namespace of the type. What type this type extends. The field list of this type. The method list of this type. How is all this data actually represented? Offset & RID encoding Most assemblies don't need to use a 4 byte value to specify heap offsets and RIDs everywhere, however we can't hard-code every offset and RID to be 2 bytes long as there could conceivably be more than 65535 items in a heap or more than 65535 fields or types defined in an assembly. So heap offsets and RIDs are only represented in the full 4 bytes if it is required; in the header information at the top of the #~ stream are 3 bits indicating if the #Strings, #GUID, or #Blob heaps use 2 or 4 bytes (the #US stream is not accessed from metadata), and the rowcount of each table. If the rowcount for a particular table is greater than 65535 then all RIDs referencing that table throughout the metadata use 4 bytes, else only 2 bytes are used. Coded tokens Not every field in a table row references a single predefined table. For example, in the TypeDef extends field, a type can extend another TypeDef (a type in the same assembly), a TypeRef (a type in a different assembly), or a TypeSpec (an instantiation of a generic type). A token would have to be used to let us specify the table along with the RID. Tokens are always 4 bytes long; again, this is rather wasteful of space. Cutting the RID down to 2 bytes would make each token 3 bytes long, which isn't really an optimum size for computers to read from memory or disk. However, every use of a token in the metadata tables can only point to a limited subset of the metadata tables. For the extends field, we only need to be able to specify one of 3 tables, which we can do using 2 bits: 0x0: TypeDef 0x1: TypeRef 0x2: TypeSpec We could therefore compress the 4-byte token that would otherwise be needed into a coded token of type TypeDefOrRef. For each type of coded token, the least significant bits encode the table the token points to, and the rest of the bits encode the RID within that table. We can work out whether each type of coded token needs 2 or 4 bytes to represent it by working out whether the maximum RID of every table that the coded token type can point to will fit in the space available. The space available for the RID depends on the type of coded token; a TypeOrMethodDef coded token only needs 1 bit to specify the table, leaving 15 bits available for the RID before a 4-byte representation is needed, whereas a HasCustomAttribute coded token can point to one of 18 different tables, and so needs 5 bits to specify the table, only leaving 11 bits for the RID before 4 bytes are needed to represent that coded token type. For example, a 2-byte TypeDefOrRef coded token with the value 0x0321 has the following bit pattern: 0 3 2 1 0000 0011 0010 0001 The first two bits specify the table - TypeRef; the other bits specify the RID. Because we've used the first two bits, we've got to shift everything along two bits: 000000 1100 1000 This gives us a RID of 0xc8. If any one of the TypeDef, TypeRef or TypeSpec tables had more than 16383 rows (2^14 - 1), then 4 bytes would need to be used to represent all TypeDefOrRef coded tokens throughout the metadata tables. Lists The third representation we need to consider is 1-to-many references; each TypeDef refers to a list of FieldDef and MethodDef belonging to that type. If we were to specify every FieldDef and MethodDef individually then each TypeDef would be very large and a variable size, which isn't ideal. There is a way of specifying a list of references without explicitly specifying every item; if we order the MethodDef and FieldDef tables by the owning type, then the field list and method list in a TypeDef only have to be a single RID pointing at the first FieldDef or MethodDef belonging to that type; the end of the list can be inferred by the field list and method list RIDs of the next row in the TypeDef table. Going back to the TypeDef If we have a look back at the definition of a TypeDef, we end up with the following reprensentation for each row: Flags - always 4 bytes Name - a #Strings heap offset. Namespace - a #Strings heap offset. Extends - a TypeDefOrRef coded token. FieldList - a single RID to the FieldDef table. MethodList - a single RID to the MethodDef table. So, depending on the number of entries in the heaps and tables within the assembly, the rows in the TypeDef table can be as small as 14 bytes, or as large as 24 bytes. Now we've had a look at how information is encoded within the metadata tables, in the next post we can see how they are arranged on disk.

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• InnoDB Compression Improvements in MySQL 5.6

  - by Inaam Rana

  MySQL 5.6 comes with significant improvements for the compression support inside InnoDB. The enhancements that we'll talk about in this piece are also a good example of community contributions. The work on these was conceived, implemented and contributed by the engineers at Facebook. Before we plunge into the details let us familiarize ourselves with some of the key concepts surrounding InnoDB compression. In InnoDB compressed pages are fixed size. Supported sizes are 1, 2, 4, 8 and 16K. The compressed page size is specified at table creation time. InnoDB uses zlib for compression. InnoDB buffer pool will attempt to cache compressed pages like normal pages. However, whenever a page is actively used by a transaction, we'll always have the uncompressed version of the page as well i.e.: we can have a page in the buffer pool in compressed only form or in a state where we have both the compressed page and uncompressed version but we'll never have a page in uncompressed only form. On-disk we'll always only have the compressed page. When both compressed and uncompressed images are present in the buffer pool they are always kept in sync i.e.: changes are applied to both atomically. Recompression happens when changes are made to the compressed data. In order to minimize recompressions InnoDB maintains a modification log within a compressed page. This is the extra space available in the page after compression and it is used to log modifications to the compressed data thus avoiding recompressions. DELETE (and ROLLBACK of DELETE) and purge can be performed without recompressing the page. This is because the delete-mark bit and the system fields DB_TRX_ID and DB_ROLL_PTR are stored in uncompressed format on the compressed page. A record can be purged by shuffling entries in the compressed page directory. This can also be useful for updates of indexed columns, because UPDATE of a key is mapped to INSERT+DELETE+purge. A compression failure happens when we attempt to recompress a page and it does not fit in the fixed size. In such case, we first try to reorganize the page and attempt to recompress and if that fails as well then we split the page into two and recompress both pages. Now lets talk about the three major improvements that we made in MySQL 5.6.Logging of Compressed Page Images:InnoDB used to log entire compressed data on the page to the redo logs when recompression happens. This was an extra safety measure to guard against the rare case where an attempt is made to do recovery using a different zlib version from the one that was used before the crash. Because recovery is a page level operation in InnoDB we have to be sure that all recompress attempts must succeed without causing a btree page split. However, writing entire compressed data images to the redo log files not only makes the operation heavy duty but can also adversely affect flushing activity. This happens because redo space is used in a circular fashion and when we generate much more than normal redo we fill up the space much more quickly and in order to reuse the redo space we have to flush the corresponding dirty pages from the buffer pool.Starting with MySQL 5.6 a new global configuration parameter innodb_log_compressed_pages. The default value is true which is same as the current behavior. If you are sure that you are not going to attempt to recover from a crash using a different version of zlib then you should set this parameter to false. This is a dynamic parameter.Compression Level:You can now set the compression level that zlib should choose to compress the data. The global parameter is innodb_compression_level - the default value is 6 (the zlib default) and allowed values are 1 to 9. Again the parameter is dynamic i.e.: you can change it on the fly.Dynamic Padding to Reduce Compression Failures:Compression failures are expensive in terms of CPU. We go through the hoops of recompress, failure, reorganize, recompress, failure and finally page split. At the same time, how often we encounter compression failure depends largely on the compressibility of the data. In MySQL 5.6, courtesy of Facebook engineers, we have an adaptive algorithm based on per-index statistics that we gather about compression operations. The idea is that if a certain index/table is experiencing too many compression failures then we should try to pack the 16K uncompressed version of the page less densely i.e.: we let some space in the 16K page go unused in an attempt that the recompression won't end up in a failure. In other words, we dynamically keep adding 'pad' to the 16K page till we get compression failures within an agreeable range. It works the other way as well, that is we'll keep removing the pad if failure rate is fairly low. To tune the padding effort two configuration variables are exposed. innodb_compression_failure_threshold_pct: default 5, range 0 - 100,dynamic, implies the percentage of compress ops to fail before we start using to padding. Value 0 has a special meaning of disabling the padding. innodb_compression_pad_pct_max: default 50, range 0 - 75, dynamic, the  maximum percentage of uncompressed data page that can be reserved as pad.

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