pure managed - Page 40 - Developer IT

Ubuntu 12.04 boot hangs with a black screen before grub menu after upgrade (gma500_gfx driver)

- by Eric van der Vlist

I am using Ubuntu on a fit-pc2 specifications and after upgrading from 10.04 to 12.04 I get a black screen at boot time (before displaying the grub menu) and the computer hangs with no disk activity. I have managed to boot Ubuntu 12.04 on a live USB key but had to add the following boot options to do so: console=tty1 or console=text acpi=off noapic nomodeset Using boot-repair, I have tried to add these options to /etc/default/grub (see this pastie log for instance) but I haven't been able to fix the black screen issue. I have tried many other things such as the workarounds mentioned on the web for PSB-GFX_drivers without any success and also to uncomment GRUB_TERMINAL=console with the result of getting a No video mode activated error. During these tests, I have managed to break /boot/grub/grub.cfg and could then hit grub in command line. This gave me the chance to check that I can boot without problem if I type: grub> set root=(hd0,1) grub> linux /vmlinuz root=/dev/sda1 ro acpi=off noapic nomodeset console=tty1 grub> initrd /initrd.img grub> boot How can I tell grub to use these options?

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.NET access to the GPU for compute purposes

- by Daniel Moth

In the distant past I talked about GPGPU and Microsoft's then approach of DirectCompute. Since then of course we now have C++ AMP coming out with Visual Studio 11, so there is a mainstream easier way for developers to access the GPU for compute purposes, using C++. The question occasionally arises of how can a .NET developer access the GPU for compute purposes from their C# (or VB) code. The answer is by interoping from the managed code to a native DLL and in the native DLL use C++ AMP. As a long term .NET developer myself, I can tell you this is straightforward. Sure, there could have been a managed wrapper for C++ AMP, but honestly that is the reason we have interop – it doesn't make much sense to invest resources to solve a problem that is already solved (most developer customers would prefer investments in other areas of Visual Studio!). Besides, interoping from C# to C++ is much easier than interoping to some of the other older approaches of GPGPU programming ;-) To help you get started with the interop approach, Igor Ostrovsky has previously shared the "Hello World" version of interoping from C# to C++ AMP in his blog post: How to use C++ AMP from C# …we then were asked specifically about how to interop from C# to C++ AMP in a Metro style application on Windows 8, so Igor delivered again with this post: How to use C++ AMP from C# using WinRT Have fun! Comments about this post by Daniel Moth welcome at the original blog.

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TEAM Webinar - WebCenter Sites Connector

- by kellsey.ruppel

TEAM Webinar - WebCenter Sites Connector Connect WebCenter Sites 11g to WebCenter Content Thursday, June 21st, 2012 10AM CDT & 5PM CDT Register Now! WebCenter Sites (formerly FatWire) is an innovative web engagement platform that is creating considerable buzz within the Oracle community, especially with the latest release, Sites 11g. Have you been wondering whether Sites is right for your organization? Did you know that you can utilize the power of WebCenter Sites right now alongside your existing WebCenter Content (UCM) implementation? Attend this webinar to learn how the TEAM WebCenter Sites Connector (learn more) allows you to leverage the Oracle WebCenter Content enterprise content management platform and deliver centrally-managed content to all your WebCenter Sites 11g deployments. Furthermore, the Digital Asset Management (DAM) capabilities in WebCenter Content allow your web marketers to spend less time creating manual renditions for multimedia files and more time on achieving your web marketing goals. If you would like to see how you can enrich your web experience using the only WebCenter Sites connector on the market, this webinar is right for you! Agenda * What's new in WebCenter Sites 11g? * How can WebCenter Content enhance the Sites experience? * Leverage centrally-managed content in Sites * Why should I get started with the TEAM Sites Connector? * Q & A session To learn more about TEAM's WebCenter Sites Connector, register for one of our two sessions today: Session One: 10AM CDT Session Two: 5PM CDT TEAM WebCenter Sites Connector

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links for 2011-02-01

- by Bob Rhubart

OTN Virtual Developer Day for WebLogic Server and WebLogic Developer Broadcasts (WebLogic Server) Mike Lehmann with details on a whole bunch of upcoming online events for those with an interest in WebLogic. (tags: WebLogic oracle otn) IOUC Summit: Open Arms and Cheese Shoes (Oracle Technology Network Blog (aka TechBlog)) Event highlights from OTN head honcho Justin Kestelyn. (tags: oracle otn IOUC) Prognostications for the Future of BI (BI & Analytics Pulse) Jacqueline Coolidge looks into the Business Intelligence crystal ball. (tags: oracle otn businessintelligence) Edwin Biemond: Some handy code for your managed Beans ( ADF & JSF ) "Back in 2009, I already a made a blogpost about some handy code which you can use in your ADF Web Application. You can say this blogspot is part 2 and here I will show you the code, I use most in my own managed Beans." - Oracle ACE Edwin Biemond (tags: java SOA oracle oracleace) Leon Smiers: Process, content and collaboration "Taking a look at today’s business, most companies still have a lot [to do] as far as adapting to and leveraging Web 2.0 possibilities is concerned." - Leon Smiers (tags: e20 oracle enterprise2.0) Antony Reynolds: Using the SOA-BPM VIrtualBox Appliance Antony says: "Recently I have been setting up some machines for fellow engineers. My base setup consists of Oracle Enterprise Linux with Oracle Virtual Box." (tags: oracle otn soa virtualization virtualbox bpm) Oracle Weblogic Server Gets Smart with CERN | SiliconANGLE CERN, the home to European particle physics, chose Oracle Weblogic Server to handle technical applications and copious HR and administrative Java-based web applications used by CERN employees. Oracle got its start by scheduling the interventions of the Large Hadron Collider (LHC). (tags: Weblogic oracle CERN) Oracle Virtual Developers Day: WebLogic - February 10, 2011 Virtual Developer Day: WebLogic - February 10, 2011. Speakers: Frances Zhao - Principal Prod Mngr, Java Platform Group; Will Lyons - Dir, WebLogic Server Prod Mgmt; Steven Button - Principal Prod Mngr, WebLogic Server; Pyounguk Cho - Principal Prod Mngr, Java Platform Group. (tags: oracle otn weblogic java)

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ArchBeat Link-o-Rama for August 2, 2013

- by OTN ArchBeat

Podcast: Data Warehousing and Oracle Data Integrator - Part 2 Part to of the discussion about Data Warehousing and Oracle Data Integrator focuses on a discussion of how data warehousing is changing and the forces driving that change. Panelists for this discussion are Uli Bethke, Oracle ACE Director Cameron Lackpour, Oracle ACE Director (and guest producer) Gurcan Orhan, and Michael Rainey. Case Management In-Depth: Cases & Case Activities Part 1 – Acivity Scope | Mark Foster FMW solution architect Mark Foster kicks off a new series with a look at the decisions made on the scope of BPM process case activities. Video: Quick Intro to WebLogic Maven Plugin 12.1.2 | Mark Nelson This YouTube video by FMW solution architect Mark Nelson offers a quick introduction to the basics of installing and using the new Oracle WebLogic 12.1.2 Maven Plugin. Running the Managed Coherence Servers Example in WebLogic Server 12c | Tim Middleton FMW solution architect Tim Middleton shares the technical details on the new Managed Coherence Servers feature and outlines how you can run the sample application available with a WebLogic Server 12.1.2 install. What’s wrong with how we develop and deliver SOA Applications today? | Mark Nelson "When we arrive at the go-live day, we have a lot of fear and uncertainty," says solution architect Mark Nelson of the typical SOA practice. "We have no idea if the system is going to work in production. We have never tested it under a production-like load, and we have not really tested it for performance, longevity, etc." OTN Latin America Tour 2013 | Kai Yu Oracle ACE Director Kai Yu shares the session abstracts from his participation in the 2013 Oracle Technology Network Latin America conference tour, which made its way through OUG conferences in Ecuador, Guatemala, Panama, and Costa Rica. Webcast: Latest Security Innovations in Oracle Database 12c Oracle Database 12c includes more new security capabilities than any other release in Oracle history! In this webcast Roxana Bradescu (Director, Oracle Database Security Product Management) will discuss these capabilities and answer your questions. (Registration required.) Thought for the Day "The main goal in life career-wise should always be to try to get paid to simply be yourself." — Kevin Smith (Born August 2, 1970) Source: brainyquote.com

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OVM Server for SPARC Enhancements

- by Owen Allen

Oracle VM Servers for SPARC saw a few improvements in Ops Center 12.2. In addition to brownfield support, we've made a number of enhancements to let you add OVM Servers for SPARC to a Server Pool and enable migration of their guests. -When you discover an OVMSS Control Domain and manage it with an Ops Center Agent, its guests are automatically discovered as well. The guest metadata is initially put in the local metadata library in the /guests directory, but you can move it from one library to another to enable migration.-Once you've discovered an OVMSS control domain, you can add it to a server pool, even if it's already configured and running logical domains. Even if live migration between OVMSS systems isn't possible due to CPU incompatibilities, you can still put them in a server pool together and enable guest recovery by configuring the CPU architecture of the guest domain as generic. -You can mark a guest's storage as shared to indicate that it's available to other managed OVM Server systems with the same back-end name. This lets you use storage not fully managed in an Ops Center library as part of guest migration. Put together, these enhancements make it much easier to manage and maintain OVMSS guests.

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using php to list some files in folders

- by Terix

I have collected many free themes from around internet. Each of them has a screenshot.jpg or png file on their folder. I want to scan all the folders for that file, and return the full file path to be used with an img html tag. I am not interested on partial path or folders where there are not screenshots. For example, if my fodler structure is: ./a/b/ ./c/d/e/screenshot.jpg ./f/ ./g/screenshot.jpg ./h/i/j/k/ ./l/m/screenshot.png ./n/o/ ./p/screenshot.jpg I want to get: ./c/d/e/screenshot.jpg ./g/screenshot.jpg ./l/m/screenshot.png ./p/screenshot.jpg I managed somehow to get a recursive function, but I figured only the way to return an array and then i can't get rid of what I don't need, and I miss png. Can anyone help me on that? the code I managed to put together is this: function getDirectoryTree( $outerDir , $x){ $dirs = array_diff( scandir( $outerDir ), Array( ".", ".." ) ); $dir_array = Array(); foreach( $dirs as $d ){ if( is_dir($outerDir."/".$d) ){ $dir_array[ $d ] = getDirectoryTree( $outerDir."/".$d , $x); }else{ if ($d==x) $dir_array[ $d ] = $d; } } return $dir_array; } $dirlist = getDirectoryTree('.','screenshot.jpg'); print_r($dirlist);

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Oracle DB, Oracle ADF, GlassFish, JDeveloper, NetBeans IDE

- by Geertjan

Today I started some experiments with Oracle guru Steven Davelaar, who lives about 20 minutes away from my place in Amsterdam by underground. Very convenient. He showed me a bunch of things in JDeveloper, while I showed him a bunch of things in NetBeans IDE. He managed to deploy an ADF application to GlassFish in JDeveloper. And, so far, I failed to do the same thing in NetBeans IDE. Quite a few (around 100) JARs are needed, aside from the question of correctly setting up or importing an ADF application, and we're still figuring out which and who and when and where. And how. And if. And why. Nonetheless, I did manage to get Oracle DB set up in NetBeans IDE, after downloading it from here: http://www.oracle.com/technetwork/products/express-edition/downloads/index.html Here's what it looks like when registered in NetBeans IDE, i.e., notice that I have a cool sample database available: Data from the above database I managed to display very easily via the various NetBeans code generators in a PrimeFaces application, exactly as has been done many times in demonstrations and tutorials everywhere, i.e., generate JPA entities, then create an EJB, then inject the EJB into a PrimeFaces data table: The next step is to somehow do the same with ADF in NetBeans IDE. I had some trouble with passwords for Oracle DB, the command line (with Steven's help) proved helpful: Wish us luck as we continue our ADF-inspired journey. This blog entry by Shay is also relevant: Deploying Oracle ADF Essentials Applications to Glassfish

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Monitor not detected after booting without monitor attached (12.04)

- by cawkie

I had a stable 12.04 machine running perfectly. The machine was booted without the monitor connected - since then the system always boots to low graphics mode. Onboard graphics (from lspci): VGA compatible controller: Intel Corporation 4 Series Chipset Integrated Graphics Controller (rev 03) Monitor: AOC e2450Swh Display widget shows monitor as laptop(!?) and system details shows graphics as Gallium 0.4 on llvmpipe (LLVM 0x300) X-server log appears to show correct monitor detected. When I boot from a live CD I get full 3d graphics I've tried the monitor on a different machine - all OK. I've tried a different monitor on this machine - same problem. Between having a working system and a broken one there have been no updates and I have made no configuration changes... EDIT: I have come to the conclusion that the problem is caused by a known issue with lightDM hanging on battery check. I've managed to get 3D graphic working by switching to using GDM - not a solution but acceptable workaround. I would still like to know what is causing the problem and how I managed to get my system into this state!

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How-to read data from selected tree node

- by Frank Nimphius

Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} By default, the SelectionListener property of an ADF bound tree points to the makeCurrent method of the FacesCtrlHierBinding class in ADF to synchronize the current row in the ADF binding layer with the selected tree node. To customize the selection behavior, or just to read the selected node value in Java, you override the default configuration with an EL string pointing to a managed bean method property. In the following I show how you change the selection listener while preserving the default ADF selection behavior. To change the SelectionListener, select the tree component in the Structure Window and open the Oracle JDeveloper Property Inspector. From the context menu, select the Edit option to create a new listener method in a new or an existing managed bean. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} For this example, I created a new managed bean. On tree node select, the managed bean code prints the selected tree node value(s) import java.util.List; import javax.el.ELContext; import javax.el.ExpressionFactory; import javax.el.MethodExpression; import javax.faces.application.Application; import javax.faces.context.FacesContext; import java.util.Iterator; import oracle.adf.view.rich.component.rich.data.RichTree; import oracle.jbo.Row; import oracle.jbo.uicli.binding.JUCtrlHierBinding; import oracle.jbo.uicli.binding.JUCtrlHierNodeBinding; import org.apache.myfaces.trinidad.event.SelectionEvent; import org.apache.myfaces.trinidad.model.CollectionModel; import org.apache.myfaces.trinidad.model.RowKeySet; import org.apache.myfaces.trinidad.model.TreeModel; public class TreeSampleBean { public TreeSampleBean() {} public void onTreeSelect(SelectionEvent selectionEvent) { //original selection listener set by ADF //#{bindings.allDepartments.treeModel.makeCurrent} String adfSelectionListener = "#{bindings.allDepartments.treeModel.makeCurrent}"; //make sure the default selection listener functionality is //preserved. you don't need to do this for multi select trees //as the ADF binding only supports single current row selection /* START PRESERVER DEFAULT ADF SELECT BEHAVIOR */ FacesContext fctx = FacesContext.getCurrentInstance(); Application application = fctx.getApplication(); ELContext elCtx = fctx.getELContext(); ExpressionFactory exprFactory = application.getExpressionFactory(); MethodExpression me = null; me = exprFactory.createMethodExpression(elCtx, adfSelectionListener, Object.class, newClass[]{SelectionEvent.class}); me.invoke(elCtx, new Object[] { selectionEvent }); /* END PRESERVER DEFAULT ADF SELECT BEHAVIOR */ RichTree tree = (RichTree)selectionEvent.getSource(); TreeModel model = (TreeModel)tree.getValue(); //get selected nodes RowKeySet rowKeySet = selectionEvent.getAddedSet(); Iterator rksIterator = rowKeySet.iterator(); //for single select configurations,this only is called once while (rksIterator.hasNext()) { List key = (List)rksIterator.next(); JUCtrlHierBinding treeBinding = null; CollectionModel collectionModel = (CollectionModel)tree.getValue(); treeBinding = (JUCtrlHierBinding)collectionModel.getWrappedData(); JUCtrlHierNodeBinding nodeBinding = null; nodeBinding = treeBinding.findNodeByKeyPath(key); Row rw = nodeBinding.getRow(); //print first row attribute. Note that in a tree you have to //determine the node type if you want to select node attributes //by name and not index String rowType = rw.getStructureDef().getDefName(); if(rowType.equalsIgnoreCase("DepartmentsView")){ System.out.println("This row is a department: " + rw.getAttribute("DepartmentId")); } else if(rowType.equalsIgnoreCase("EmployeesView")){ System.out.println("This row is an employee: " + rw.getAttribute("EmployeeId")); } else{ System.out.println("Huh????"); } // ... do more useful stuff here } } -------------------- Download JDeveloper 11.1.2.1 Sample Workspace

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Searching integer sequences

- by David Gibson

I have a fairly complex search problem that I've managed to reduce to the following description. I've been googling but haven't been able to find an algorithm that seems to fit my problem cleanly. In particular the need to skip arbitrary integers. Maybe someone here can point me to something? Take a sequence of integers A, for example (1 2 3 4) Take various sequences of integers and test if any of them match A such that. A contains all of the integers in the tested sequence The ordering of the integers in the tested sequence are the same in A We don't care about any integers in A that are not in the test sequence We want all matching test sequences, not just the first. An example A = (1 2 3 4) B = (1 3) C = (1 3 4) D = (3 1) E = (1 2 5) B matches A C matches A D does not match A as the ordering is different E does not match A as it contains an integer not in A I hope that this explanation is clear enough. The best I've managed to do is to contruct a tree of the test sequences and iterate over A. The need to be able to skip integers leads to a lot of unsuccessful search paths. Thanks Reading some suggestions I feel that I have to clarify a couple of points that I left too vague. Repeated numbers are allowed, in fact this is quite important as it allows a single test sequence to match A is multiple ways A = (1234356), B = (236), matches could be either -23---6 or -2--3-6 I expect there to be a very large number of test sequences, in the thousands at least and sequence A will tend to have a max length of maybe 20. Thus simply trying to match each test sequence one by one by iterating becomes extremely inefficient. Sorry if this wasn't clear.

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MSDN Live 2010 – Delivered : 24 sessions (4 x 6) on Visual Studio and Team Foundation Server

- by terje

We (Mikael Nitell and me) got a whole track on the Norwegian MSDN Live tour this year. We did these as a pair, and covered 4 cities over 4 days, 6 sessions per day, taking 8 hours to come through it. The Islandic volcano made the travels a bit rough, but we managed 6 flights out of 8. The first one had to go by van instead, 7-8 hour drive each way together with other MSDN Live presenters – a memorable tour! Oslo was the absolute top point. We had to change hall to a bigger one. People were crowding, and even the big hall was packed! The presentations were mostly based on demos, but we had a few slides as well. They have been uploaded to my SkyDrive. Info to aliens – some of the text may be Norwegian. The sessions were as follows: Overview of news in Visual Studio and Team Foundation server 2010 Ensuring Quality with VS/TFS 2010 Releasing products with VS/TFS 2010 No More No Repro with VS/TFS 2010 Performance Testing and Parallel Programming with VS/TFS 2010 Migrating to VS/TFS 2010 Tips, tricks, news and some best practices with VS/TFS 2010 In the coming days, I will post up examples from the demos too, with explanations of how they are intended to work. These entries will also contain stuff we had to remove from the actual presentations due to the time constraints. We managed to create recordings of two of the sessions, which will be uploaded to Channel 9 by Microsoft, afaik. I will update this blog with information about exact locations when that is done. Also note we’re (read:Osiris Data AS) running both Upgrade and Deep Dive courses on VS/TFS 2010 now in May. Please look here for more info. If you want to be informed, follow me on Twitter. All blog entries will be announced on twitter.

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Notification framework for object lifecycle

- by rlandster

I am looking for an application, framework, or library that would help us with "object life-cycle management". There are many things that are created for users, departments, and services that, all too often, are left unmanaged. Some examples: user accounts groups SSL certificates access rights databases software license provisionings storage list-serve accounts These objects are created and managed by a wide variety of applications and systems. Typically, a user (person) requests (either explicitly or implicitly) one of these objects. A centralized management tool would help us manage such administration chores as: What objects does user X currently own/manage? Move the ownership of object P to user X; move all objects owned by user X (who was just been fired) to user Y. For all objects of type T that have expired be sure the objects have been disabled or deleted by their provider. How many active (expired, about-to-expire) objects of type P are there? Send periodic notifications to all users who own active objects of type P reminding them of what they own. There is a security alert for objects of type P; send a notification to all users who own these types of objects to take a specific remedial action. Delete or disable a set of objects based on expiration (or some other criteria). These objects are directly managed through their own applications (Active Directory, MySql, file systems, etc.) and may even have their own notification systems, but I want to centralize this into an "object management system". The OMS should allow the association with an external identity provider that defines who the users and groups are (e.g., LDAP, Active Directory) creation of objects association of an object to a specific user and/or group association with an expiration date creation of flexible reporting including letting users know what objects they currently own and their expiration dates integration with an external object "provider" via a plug-in We could write something from scratch, but I am hoping there is something already out there that will help, either an entire application or a set of libraries that provide much of what is needed. Any ideas?

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What is the simplest way to render video into memory (for drawing to a texture) in .NET?

- by sebf

In my project I would like to be able to play back video on surfaces in the world. I intend to do this by having the video frames rendered to a block of memory, then use this to update a texture each frame. Everything is in place - except for the part that actually gets the video. I have looked on Google and found that the video library world is very expansive (and geared towards video processing), and am having trouble finding a suitable one. FFMpeg is very comprehensive, but is an entire suite and would take a good amount of work to integrate. So far the most promising library I've found is the one based on the VLC player libraries - by virtue of it using the same resources as VLC Player it is known to be very capable; it also renders to blocks of memory, but the API (at least of the one on Codeplex) is more of a port of the C++ API rather than a managed wrapper. The 'solution' can be any wrapper/API/library, but with characteristics that make it suitable for use in a rendering engine, namely: Renders the video frame data to memory, so it can be picked up and passed to a texture on the GPU easily. Super simple - all that is needed is a way to load, jump and render a frame programatically - ideally it would use the systems codecs and not require an assortment of plugins. Permissive license (LGPL or more free-er) .NET bindings at least; all the better if it is natively managed Can anyone suggest a lightweight, (.NET) library, that can take a video file, and spit out some frames into a byte[]?

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How to start WebLogic Server using default scripts?

- by Luz Mestre-Oracle

There are a few common issues reported when starting weblogic server using scripts. 1. User is not able to access weblogic console. 2. After a few days/hours weblogic server stops abruptly. 3. When user closes putty, they are not able to connect to weblogic server anymore. 4. When user closes windows command prompt, they are not able to connect to weblogic server anymore. 5. Weblogic is started using startManagedWebLogic.cmd/startManagedWebLogic.sh. By default, WebLogic Server does not run in background mode, so after you close the window the process finishes as well. In Linux/Unix based platforms, you need to use: nohup ./startManagedWebLogic.sh <Server> <URL> & In Windows platforms, you need to start Managed Servers using Windows Services: How to Install MS Windows Services For FMW 11g WebLogic Domain Admin and Managed Servers (Doc ID 1060058.1) http://docs.oracle.com/cd/E23943_01/web.1111/e13708/winservice.htm There a few more reasons that could cause similar symptoms, like JVM crash, signals sent by the Operating System, and many other reasons. But the above steps is the first one to start. Enjoy!

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Webcast: DB Enterprise User Security Integration with Oracle Directory Services

- by B Shashikumar

The typical enterprise has a large number of DBA (Database administrator) accounts that are locally managed, which is often very costly, problematic and error-prone. Databases are a crucial component of your enterprise IT infrastructure, housing sensitive corporate data and database user accounts and privileges. To ensure the integrity of your enterprise's data, it's imperative to have a well-managed identity management system. This begins with centralized management of user accounts and access rights. Enterprise User Security (EUS), an Oracle Database Enterprise Edition feature, combined with Oracle Identity Management, gives you the ability to centrally manage database users and their authorizations in one central place. The cost of user provisioning and password resets is dramatically reduced. This technology is a must for new application development and should be considered for existing applications as well. Join Oracle Advisors for a live webcast on Jul 11 at 8am Pacific Time where Oracle experts will briefly introduce EUS, followed by a detailed discussion about the various directory options that are supported, including integration with Microsoft Active Directory. We'll conclude how to avoid common pitfalls deploying EUS with directory services. To register for this event, click here

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Configuring network to set wlan0 as primary

- by Sheed

I recently had to rebuild my pc and decided to go for ubuntu 14.04. I think the mistake I made was I started from a 12.04 install disk instead of the 12.10 disk I'd used previously and when given the option set my primary connection as ethernet (because the wireless option didn't work). After upgrading to 14.04 etc, I managed to get the wireless working, or more using steps like ifconfig -a and the likes I managed to prove that the wireless card etc. is all installed and working. However every time I boot without a hard wired connection plugged in I get the message "waiting for network configuration". I can then once it's booted without a network get my wirless working using sudo ifconfig wlan0 up iwlist wlan0 scan This seems to kick the wireless module into life and it appears in the GUI and I can then select a network, however all the options like edit network and disconnect etc are all greyed out. What I would like of course is if the WLAN0 was just set as my primary default network so I've been looking for a solution to this and it would seem that I need to adjust the old /etc/network/interfaces file but when I try to do so using the sudo vi /etc/network/interfaces command I, well I simply have no idea what I'm doing. Other than that typing :q! gets me out of there before I do to much damage! As far as I can tell (by navigating to the file in the GUI) the output of my /etc/network/interfaces is as follows: (obviously not including the " in each line that's just to break the heading rule of the #) "# This file describes the network interfaces available on your system "# and how to activate them. For more information, see interfaces(5). "# The loopback network interface auto lo iface lo inet loopback "# The primary network interface auto eth0 iface eth0 inet dhcp If this is the case then this clearly doesn't contain what it should do but I don't how to fix it. Nor do I even know if I'm on the right track. Any help would be appreciated thanks :)

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How do I install Kodos in 12.10?

- by Brutus

In previous Ubuntu version I used Kodos extensively. But the package has been dropped in 12.10. It's a neat regular expression testing tool. It's hard to find an alternative that is not Windows only (or Air, or uses action script which bails on more complicated RegEx, or works in Wine - well kinda, but not really..., etc.). So I tried to install Kodos from source, which seems to work (download sourceball and setup.py) but it won't run because of missing PyQT dependencies (that I can't manage to fulfill with anything install-able trough standard packages). I then tried to install PyQT manually (which seems to require manual install of SIP and QT too) and instead of pip I have to use configure.py and qmake. It throws error after error at me. I tried to overcome one after another for over an hour but no luck. It even managed to break Calibre and Music Brains Picard. So I purged all the stuff, reinstalled python-sipand python-qt4 from the standard packages and gave up. Has anyone managed to get Kodos running on 12.10? Or any hints on how to do it?

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Core Data error when assigning variable with one-to-one relationship

- by Hoang Pham

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Why don't I just build the whole web app in Javascript and Javascript HTML Templates?

- by viatropos

I'm getting to the point on an app where I need to start caching things, and it got me thinking... In some parts of the app, I render table rows (jqGrid, slickgrid, etc.) or fancy div rows (like in the New Twitter) by grabbing pure JSON and running it through something like Mustache, jquery.tmpl, etc. In other parts of the app, I just render the info in pure HTML (server-side HAML templates), and if there's searching/paginating, I just go to a new URL and load a new HTML page. Now the problem is in caching and maintainability. On one hand I'm thinking, if everything was built using Javascript HTML Templates, then my app would serve just an HTML layout/shell, and a bunch of JSON. If you look at the Facebook and Twitter HTML source, that's basically what they're doing (95% json/javascript, 5% html). This would make it so my app only needed to cache JSON (pages, actions, and/or records). Which means you'd hit the cache no matter if you were some remote api developer accessing a JSON api, or the strait web app. That is, I don't need 2 caches, one for the JSON, one for the HTML. That seems like it'd cut my cache store down in half, and streamline things a little bit. On the other hand, I'm thinking, from what I've seen/experienced, generating static HTML server-side, and caching that, seems to be much better performance wise cross-browser; you get the graphics instantly and don't have to wait that split-second for javascript to render it. StackOverflow seems to do everything in plain HTML, and you can tell... everything appears at once. Notice how though on twitter.com, the page is blank for .5-1 seconds, and the page chunks in: the javascript has to render the json. The downside with this is that, for anything dynamic (like endless scrolling, or grids), I'd have to create javascript templates anyway... so now I have server-side HAML templates, client-side javascript templates, and a lot more to cache. My question is, is there any consensus on how to approach this? What are the benefits and drawbacks from your experience of mixing the two versus going 100% with one over the other? Update: Some reasons that factor into why I haven't yet made the decision to go with 100% javascript templating are: Performance. Haven't formally tested, but from what I've seen, raw html renders faster and more fluidly than javascript-generated html cross-browser. Plus, I'm not sure how mobile devices handle dynamic html performance-wise. Testing. I have a lot of integration tests that work well with static HTML, so switching to javascript-only would require 1) more focused pure-javascript testing (jasmine), and 2) integrating javascript into capybara integration tests. This is just a matter of time and work, but it's probably significant. Maintenance. Getting rid of HAML. I love HAML, it's so easy to write, it prints pretty HTML... It makes code clean, it makes maintenance easy. Going with javascript, there's nothing as concise. SEO. I know google handles the ajax /#!/path, but haven't grasped how this will affect other search engines and how older browsers handle it. Seems like it'd require a significant setup.

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displaying search results with two or more queries

- by fusion

in my search form, if the user types 'good', it displays all the results which contain the keyword 'good'. however if the user types in 'good sweetest', it displays no results because there is no record with the two words appearing together; BUT appearing in an entry at different places. for example, the record says: A good action is an ever-remaining store and a pure yield the user types in 'good', it will show up this record, but if the user types in 'good' + 'pure', it will not show anything. what i would like is that if the user types in 'good' + 'pure' it should records containing these keywords highlighting them. search.php code: $search_result = ""; $search_result = $_POST["q"]; $search_result = trim($search_result); //Check if the string is empty if ($search_result == "") { echo "<p class='error'>Search Error. Please Enter Your Search Query.</p>" ; exit(); } if ($search_result == "%" || $search_result == "_" || $search_result == "+" ) { echo "<p class='error1'>Search Error. Please Enter a Valid Search Query.</p>" ; exit(); } $result = mysql_query('SELECT cQuotes, vAuthor, cArabic, vReference FROM thquotes WHERE cQuotes LIKE "%' . mysql_real_escape_string($search_result) .'%" ORDER BY idQuotes DESC', $conn) or die ('Error: '.mysql_error()); function h($s) { echo htmlspecialchars($s, ENT_QUOTES); } function highlightWords($string, $word) { $string = preg_replace("/".preg_quote($word, "/")."/i", "<span class='highlight'>$0</span>", $string); /*** return the highlighted string ***/ return $string; } ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:18px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> search.html: <form name="myform" class="wrapper"> <input type="text" name="q" onkeyup="showUser()" class="txt_search"/> <input type="button" name="button" onclick="showUser()" class="button"/> <p> <div id="txtHint"></div> </form>

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displaying search results of more than one word

- by fusion

in my search form, if the user types 'good', it displays all the results which contain the keyword 'good'. however if the user types in 'good sweetest', it displays no results because there is no record with the two words appearing together; BUT appearing in an entry at different places. for example, the record says: A good action is an ever-remaining store and a pure yield the user types in 'good', it will show up this record, but if the user types in 'good' + 'pure', it will not show anything. or if the record contains the keyword 'good-deeds' and if the user types in 'good deeds' without the hyphen, it will not show anything. what i would like is that if the user types in 'good' + 'pure' or 'good deeds' it should records containing these keywords highlighting them. search.php code: $search_result = ""; $search_result = $_POST["q"]; $search_result = trim($search_result); //Check if the string is empty if ($search_result == "") { echo "<p class='error'>Search Error. Please Enter Your Search Query.</p>" ; exit(); } if ($search_result == "%" || $search_result == "_" || $search_result == "+" ) { echo "<p class='error1'>Search Error. Please Enter a Valid Search Query.</p>" ; exit(); } $result = mysql_query('SELECT cQuotes, vAuthor, cArabic, vReference FROM thquotes WHERE cQuotes LIKE "%' . mysql_real_escape_string($search_result) .'%" ORDER BY idQuotes DESC', $conn) or die ('Error: '.mysql_error()); function h($s) { echo htmlspecialchars($s, ENT_QUOTES); } function highlightWords($string, $word) { $string = preg_replace("/".preg_quote($word, "/")."/i", "<span class='highlight'>$0</span>", $string); /*** return the highlighted string ***/ return $string; } ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:18px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> search.html: <form name="myform" class="wrapper"> <input type="text" name="q" onkeyup="showUser()" class="txt_search"/> <input type="button" name="button" onclick="showUser()" class="button"/> <p> <div id="txtHint"></div> </form>

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Using the Static Code Analysis feature of Visual Studio (Premium/Ultimate) to find memory leakage problems

- by terje

Memory for managed code is handled by the garbage collector, but if you use any kind of unmanaged code, like native resources of any kind, open files, streams and window handles, your application may leak memory if these are not properly handled. To handle such resources the classes that own these in your application should implement the IDisposable interface, and preferably implement it according to the pattern described for that interface. When you suspect a memory leak, the immediate impulse would be to start up a memory profiler and start digging into that. However, before you follow that impulse, do a Static Code Analysis run with a ruleset tuned to finding possible memory leaks in your code. If you get any warnings from this, fix them before you go on with the profiling. How to use a ruleset In Visual Studio 2010 (Premium and Ultimate editions) you can define your own rulesets containing a list of Static Code Analysis checks. I have defined the memory checks as shown in the lists below as ruleset files, which can be downloaded – see bottom of this post. When you get them, you can easily attach them to every project in your solution using the Solution Properties dialog. Right click the solution, and choose Properties at the bottom, or use the Analyze menu and choose “Configure Code Analysis for Solution”: In this dialog you can now choose the Memorycheck ruleset for every project you want to investigate. Pressing Apply or Ok opens every project file and changes the projects code analysis ruleset to the one we have specified here. How to define your own ruleset (skip this if you just download my predefined rulesets) If you want to define the ruleset yourself, open the properties on any project, choose Code Analysis tab near the bottom, choose any ruleset in the drop box and press Open Clear out all the rules by selecting “Source Rule Sets” in the Group By box, and unselect the box Change the Group By box to ID, and select the checks you want to include from the lists below. Note that you can change the action for each check to either warning, error or none, none being the same as unchecking the check. Now go to the properties window and set a new name and description for your ruleset. Then save (File/Save as) the ruleset using the new name as its name, and use it for your projects as detailed above. It can also be wise to add the ruleset to your solution as a solution item. That way it’s there if you want to enable Code Analysis in some of your TFS builds. Running the code analysis In Visual Studio 2010 you can either do your code analysis project by project using the context menu in the solution explorer and choose “Run Code Analysis”, you can define a new solution configuration, call it for example Debug (Code Analysis), in for each project here enable the Enable Code Analysis on Build In Visual Studio Dev-11 it is all much simpler, just go to the Solution root in the Solution explorer, right click and choose “Run code analysis on solution”. The ruleset checks The following list is the essential and critical memory checks. CheckID Message Can be ignored ? Link to description with fix suggestions CA1001 Types that own disposable fields should be disposable No http://msdn.microsoft.com/en-us/library/ms182172.aspx CA1049 Types that own native resources should be disposable Only if the pointers assumed to point to unmanaged resources point to something else http://msdn.microsoft.com/en-us/library/ms182173.aspx CA1063 Implement IDisposable correctly No http://msdn.microsoft.com/en-us/library/ms244737.aspx CA2000 Dispose objects before losing scope No http://msdn.microsoft.com/en-us/library/ms182289.aspx CA2115 1 Call GC.KeepAlive when using native resources See description http://msdn.microsoft.com/en-us/library/ms182300.aspx CA2213 Disposable fields should be disposed If you are not responsible for release, of if Dispose occurs at deeper level http://msdn.microsoft.com/en-us/library/ms182328.aspx CA2215 Dispose methods should call base class dispose Only if call to base happens at deeper calling level http://msdn.microsoft.com/en-us/library/ms182330.aspx CA2216 Disposable types should declare a finalizer Only if type does not implement IDisposable for the purpose of releasing unmanaged resources http://msdn.microsoft.com/en-us/library/ms182329.aspx CA2220 Finalizers should call base class finalizers No http://msdn.microsoft.com/en-us/library/ms182341.aspx Notes: 1) Does not result in memory leak, but may cause the application to crash The list below is a set of optional checks that may be enabled for your ruleset, because the issues these points too often happen as a result of attempting to fix up the warnings from the first set. ID Message Type of fault Can be ignored ? Link to description with fix suggestions CA1060 Move P/invokes to NativeMethods class Security No http://msdn.microsoft.com/en-us/library/ms182161.aspx CA1816 Call GC.SuppressFinalize correctly Performance Sometimes, see description http://msdn.microsoft.com/en-us/library/ms182269.aspx CA1821 Remove empty finalizers Performance No http://msdn.microsoft.com/en-us/library/bb264476.aspx CA2004 Remove calls to GC.KeepAlive Performance and maintainability Only if not technically correct to convert to SafeHandle http://msdn.microsoft.com/en-us/library/ms182293.aspx CA2006 Use SafeHandle to encapsulate native resources Security No http://msdn.microsoft.com/en-us/library/ms182294.aspx CA2202 Do not dispose of objects multiple times Exception (System.ObjectDisposedException) No http://msdn.microsoft.com/en-us/library/ms182334.aspx CA2205 Use managed equivalents of Win32 API Maintainability and complexity Only if the replace doesn’t provide needed functionality http://msdn.microsoft.com/en-us/library/ms182365.aspx CA2221 Finalizers should be protected Incorrect implementation, only possible in MSIL coding No http://msdn.microsoft.com/en-us/library/ms182340.aspx Downloadable ruleset definitions I have defined three rulesets, one called Inmeta.Memorycheck with the rules in the first list above, and Inmeta.Memorycheck.Optionals containing the rules in the second list, and the last one called Inmeta.Memorycheck.All containing the sum of the two first ones. All three rulesets can be found in the zip archive “Inmeta.Memorycheck” downloadable from here. Links to some other resources relevant to Static Code Analysis MSDN Magazine Article by Mickey Gousset on Static Code Analysis in VS2010 MSDN : Analyzing Managed Code Quality by Using Code Analysis, root of the documentation for this Preventing generated code from being analyzed using attributes Online training course on Using Code Analysis with VS2010 Blogpost by Tatham Oddie on custom code analysis rules How to write custom rules, from Microsoft Code Analysis Team Blog Microsoft Code Analysis Team Blog

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Memory Efficient Windows SOA Server

- by Antony Reynolds

Installing a Memory Efficient SOA Suite 11.1.1.6 on Windows Server Well 11.1.1.6 is now available for download so I thought I would build a Windows Server environment to run it. I will minimize the memory footprint of the installation by putting all functionality into the Admin Server of the SOA Suite domain. Required Software 64-bit JDK SOA Suite If you want 64-bit then choose “Generic” rather than “Microsoft Windows 32bit JVM” or “Linux 32bit JVM” This has links to all the required software. If you choose “Generic” then the Repository Creation Utility link does not show, you still need this so change the platform to “Microsoft Windows 32bit JVM” or “Linux 32bit JVM” to get the software. Similarly if you need a database then you need to change the platform to get the link to XE for Windows or Linux. If possible I recommend installing a 64-bit JDK as this allows you to assign more memory to individual JVMs. Windows XE will work, but it is better if you can use a full Oracle database because of the limitations on XE that sometimes cause it to run out of space with large or multiple SOA deployments. Installation Steps The following flow chart outlines the steps required in installing and configuring SOA Suite. The steps in the diagram are explained below. 64-bit? Is a 64-bit installation required? The Windows & Linux installers will install 32-bit versions of the Sun JDK and JRockit. A separate JDK must be installed for 64-bit. Install 64-bit JDK The 64-bit JDK can be either Hotspot or JRockit. You can choose either JDK 1.7 or 1.6. Install WebLogic If you are using 64-bit then install WebLogic using “java –jar wls1036_generic.jar”. Make sure you include Coherence in the installation, the easiest way to do this is to accept the “Typical” installation. SOA Suite Required? If you are not installing SOA Suite then you can jump straight ahead and create a WebLogic domain. Install SOA Suite Run the SOA Suite installer and point it at the existing Middleware Home created for WebLogic. Note to run the SOA installer on Windows the user must have admin privileges. I also found that on Windows Server 2008R2 I had to start the installer from a command prompt with administrative privileges, granting it privileges when it ran caused it to ignore the jreLoc parameter. Database Available? Do you have access to a database into which you can install the SOA schema. SOA Suite requires access to an Oracle database (it is supported on other databases but I would always use an oracle database). Install Database I use an 11gR2 Oracle database to avoid XE limitations. Make sure that you set the database character set to be unicode (AL32UTF8). I also disabled the new security settings because they get in the way for a developer database. Don’t forget to check that number of processes is at least 150 and number of sessions is not set, or is set to at least 200 (in the DB init parameters). Run RCU The SOA Suite database schemas are created by running the Repository Creation Utility. Install the “SOA and BPM Infrastructure” component to support SOA Suite. If you keep the schema prefix as “DEV” then the config wizard is easier to complete. Run Config Wizard The Config wizard creates the domain which hosts the WebLogic server instances. To get a minimum footprint SOA installation choose the “Oracle Enterprise Manager” and “Oracle SOA Suite for developers” products. All other required products will be automatically selected. The “for developers” installs target the appropriate components at the AdminServer rather than creating a separate managed server to house them. This reduces the number of JVMs required to run the system and hence the amount of memory required. This is not suitable for anything other than a developer environment as it mixes the admin and runtime functions together in a single server. It also takes a long time to load all the required modules, making start up a slow process. If it exists I would recommend running the config wizard found in the “oracle_common/common/bin” directory under the middleware home. This should have access to all the templates, including SOA. If you also want to run BAM in the same JVM as everything else then you need to “Select Optional Configuration” for “Managed Servers, Clusters and Machines”. To target BAM at the AdminServer delete the “bam_server1” managed server that is created by default. This will result in BAM being targeted at the AdminServer. Installation Issues I had a few problems when I came to test everything in my mega-JVM. Following applications were not targeted and so I needed to target them at the AdminServer: b2bui composer Healthcare UI FMW Welcome Page Application (11.1.0.0.0) How Memory Efficient is It? On a Windows 2008R2 Server running under VirtualBox I was able to bring up both the 11gR2 database and SOA/BPM/BAM in 3G memory. I allocated a minimum 512M to the PermGen and a minimum of 1.5G for the heap. The setting from setSOADomainEnv are shown below: set DEFAULT_MEM_ARGS=-Xms1536m -Xmx2048m set PORT_MEM_ARGS=-Xms1536m -Xmx2048m set DEFAULT_MEM_ARGS=%DEFAULT_MEM_ARGS% -XX:PermSize=512m -XX:MaxPermSize=768m set PORT_MEM_ARGS=%PORT_MEM_ARGS% -XX:PermSize=512m -XX:MaxPermSize=768m I arrived at these numbers by monitoring JVM memory usage in JConsole. Task Manager showed total system memory usage at 2.9G – just below the 3G I allocated to the VM. Performance is not stellar but it runs and I could run JDeveloper alongside it on my 8G laptop, so in that sense it was a result!

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Subterranean IL: Generics and array covariance

- by Simon Cooper

Arrays in .NET are curious beasts. They are the only built-in collection types in the CLR, and SZ-arrays (single dimension, zero-indexed) have their own commands and IL syntax. One of their stranger properties is they have a kind of built-in covariance long before generic variance was added in .NET 4. However, this causes a subtle but important problem with generics. First of all, we need to briefly recap on array covariance. SZ-array covariance To demonstrate, I'll tweak the classes I introduced in my previous posts: public class IncrementableClass { public int Value; public virtual void Increment(int incrementBy) { Value += incrementBy; } } public class IncrementableClassx2 : IncrementableClass { public override void Increment(int incrementBy) { base.Increment(incrementBy); base.Increment(incrementBy); } } In the CLR, SZ-arrays of reference types are implicitly convertible to arrays of the element's supertypes, all the way up to object (note that this does not apply to value types). That is, an instance of IncrementableClassx2[] can be used wherever a IncrementableClass[] or object[] is required. When an SZ-array could be used in this fashion, a run-time type check is performed when you try to insert an object into the array to make sure you're not trying to insert an instance of IncrementableClass into an IncrementableClassx2[]. This check means that the following code will compile fine but will fail at run-time: IncrementableClass[] array = new IncrementableClassx2[1]; array[0] = new IncrementableClass(); // throws ArrayTypeMismatchException These checks are enforced by the various stelem* and ldelem* il instructions in such a way as to ensure you can't insert a IncrementableClass into a IncrementableClassx2[]. For the rest of this post, however, I'm going to concentrate on the ldelema instruction. ldelema This instruction pops the array index (int32) and array reference (O) off the stack, and pushes a pointer (&) to the corresponding array element. However, unlike the ldelem instruction, the instruction's type argument must match the run-time array type exactly. This is because, once you've got a managed pointer, you can use that pointer to both load and store values in that array element using the ldind* and stind* (load/store indirect) instructions. As the same pointer can be used for both input and output to the array, the type argument to ldelema must be invariant. At the time, this was a perfectly reasonable restriction, and maintained array type-safety within managed code. However, along came generics, and with it the constrained callvirt instruction. So, what happens when we combine array covariance and constrained callvirt? .method public static void CallIncrementArrayValue() { // IncrementableClassx2[] arr = new IncrementableClassx2[1] ldc.i4.1 newarr IncrementableClassx2 // arr[0] = new IncrementableClassx2(); dup newobj instance void IncrementableClassx2::.ctor() ldc.i4.0 stelem.ref // IncrementArrayValue<IncrementableClass>(arr, 0) // here, we're treating an IncrementableClassx2[] as IncrementableClass[] dup ldc.i4.0 call void IncrementArrayValue<class IncrementableClass>(!!0[],int32) // ... ret } .method public static void IncrementArrayValue<(IncrementableClass) T>( !!T[] arr, int32 index) { // arr[index].Increment(1) ldarg.0 ldarg.1 ldelema !!T ldc.i4.1 constrained. !!T callvirt instance void IIncrementable::Increment(int32) ret } And the result: Unhandled Exception: System.ArrayTypeMismatchException: Attempted to access an element as a type incompatible with the array. at IncrementArrayValue[T](T[] arr, Int32 index) at CallIncrementArrayValue() Hmm. We're instantiating the generic method as IncrementArrayValue<IncrementableClass>, but passing in an IncrementableClassx2[], hence the ldelema instruction is failing as it's expecting an IncrementableClass[]. On features and feature conflicts What we've got here is a conflict between existing behaviour (ldelema ensuring type safety on covariant arrays) and new behaviour (managed pointers to object references used for every constrained callvirt on generic type instances). And, although this is an edge case, there is no general workaround. The generic method could be hidden behind several layers of assemblies, wrappers and interfaces that make it a requirement to use array covariance when calling the generic method. Furthermore, this will only fail at runtime, whereas compile-time safety is what generics were designed for! The solution is the readonly. prefix instruction. This modifies the ldelema instruction to ignore the exact type check for arrays of reference types, and so it lets us take the address of array elements using a covariant type to the actual run-time type of the array: .method public static void IncrementArrayValue<(IncrementableClass) T>( !!T[] arr, int32 index) { // arr[index].Increment(1) ldarg.0 ldarg.1 readonly. ldelema !!T ldc.i4.1 constrained. !!T callvirt instance void IIncrementable::Increment(int32) ret } But what about type safety? In return for ignoring the type check, the resulting controlled mutability pointer can only be used in the following situations: As the object parameter to ldfld, ldflda, stfld, call and constrained callvirt instructions As the pointer parameter to ldobj or ldind* As the source parameter to cpobj In other words, the only operations allowed are those that read from the pointer; stind* and similar that alter the pointer itself are banned. This ensures that the array element we're pointing to won't be changed to anything untoward, and so type safety within the array is maintained. This is a typical example of the maxim that whenever you add a feature to a program, you have to consider how that feature interacts with every single one of the existing features. Although an edge case, the readonly. prefix instruction ensures that generics and array covariance work together and that compile-time type safety is maintained. Tune in next time for a look at the .ctor generic type constraint, and what it means.

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