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• Deploying an ADF Secure Application using WLS Console

  - by juan.ruiz

  Last week I worked on a requirement from a customer that wanted to understand how to deploy to WLS an application with ADF Security without using JDeveloper. The main question was, what steps where needed in order to set up Enterprise Roles, Security Policies and Application Credentials. In this entry I will explain the steps taken using JDeveloper 11.1.1.2. 0 Requirements: Instead of building a sample application from scratch, we can use Andrejus 's sample application that contains all the security pieces that we need. Open and migrate the project. Also make sure you adjust the database settings accordingly. Creating the EAR file Review the Security settings of the application by going into the Application -> Secure menu and see that there are two enterprise roles as well as the ADF Policies enforcing security on the main page. Make sure the Application Module uses the Data Source instead of JDBC URL for its connection type, also take note of the data source name - in my case I have: java:comp/env/jdbc/HrDS To facilitate the access to this application once we deploy it. Go to your ViewController project properties select the Java EE Application category and give it a meaningful name to the context root as well to the Application Name Go to the ADFSecurityWL Application properties -> Deployment  and create a new EAR deployment profile. Uncheck the Auto generate and Synchronize weblogic-jdbc.xml Descriptors During Deployment Deploy the application as an EAR file. Deploying the Application to WLS using the WLS Console On the WLS console create a JNDI data source. This is the part that I found more tricky of the hole exercise given that the name should match the AM's data source name, however the naming convention that worked for me was jdbc.HrDS Now, deploy the application manually by selecting deployments ->Install look for the EAR and follow the default steps. If this is the firs time you deploy the application, once the deployment finishes you will be asked to Activate Changes on the domain, these changes contain all the security policies and application roles insertion into the WLS instance. Creating Roles and User Groups for the Application To finish the after-deployment set up, we need to create the groups that are the equivalent of the Enterprise Roles of ADF Security. For our sample we have two Enterprise Roles employeesApplication and managersApplication. After that, we create the application users and assign them into their respective groups. Now we can run the application and test the security constraints

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• Type Casting variables in PHP: Is there a practical example?

  - by Stephen

  PHP, as most of us know, has weak typing. For those who don't, PHP.net says: PHP does not require (or support) explicit type definition in variable declaration; a variable's type is determined by the context in which the variable is used. Love it or hate it, PHP re-casts variables on-the-fly. So, the following code is valid: $var = "10"; $value = 10 + $var; var_dump($value); // int(20) PHP also alows you to explicitly cast a variable, like so: $var = "10"; $value = 10 + $var; $value = (string)$value; var_dump($value); // string(2) "20" That's all cool... but, for the life of me, I cannot conceive of a practical reason for doing this. I don't have a problem with strong typing in languages that support it, like Java. That's fine, and I completely understand it. Also, I'm aware of—and fully understand the usefulness of—type hinting in function parameters. The problem I have with type casting is explained by the above quote. If PHP can swap types at-will, it can do so even after you force cast a type; and it can do so on-the-fly when you need a certain type in an operation. That makes the following valid: $var = "10"; $value = (int)$var; $value = $value . ' TaDa!'; var_dump($value); // string(8) "10 TaDa!" So what's the point? Can anyone show me a practical application or example of type casting—one that would fail if type casting were not involved? I ask this here instead of SO because I figure practicality is too subjective. Edit in response to Chris' comment Take this theoretical example of a world where user-defined type casting makes sense in PHP: You force cast variable $foo as int -- (int)$foo. You attempt to store a string value in the variable $foo. PHP throws an exception!! <--- That would make sense. Suddenly the reason for user defined type casting exists! The fact that PHP will switch things around as needed makes the point of user defined type casting vague. For example, the following two code samples are equivalent: // example 1 $foo = 0; $foo = (string)$foo; $foo = '# of Reasons for the programmer to type cast $foo as a string: ' . $foo; // example 2 $foo = 0; $foo = (int)$foo; $foo = '# of Reasons for the programmer to type cast $foo as a string: ' . $foo;

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• DBCC MEMUSAGE in 2005/8 ?

  - by steveh99999

  I used to like using undocumented command DBCC MEMUSAGE in SQL 2000 to see which tables were using space in SQL data cache. In SQL 2005, this command is not longer present. Instead a DMV – sys.dm_os_buffer_descriptors – can be used to display data cache contents,  but this doesn’t quite give you the same output as DBCC MEMUSAGE. I’m also aware that you can use Quest’s spotlight tool to view a summary of data cache contents. Using  this post by Umachandar Jayachandran  of Microsoft, I was able to create the following equivalent for SQL 2005/8. I’ve wrapped Umachandar’s original query in a CTE to produce summary information :- ;WITH memusage_CTE AS (SELECT bd.database_id, bd.file_id, bd.page_id, bd.page_type , COALESCE(p1.object_id, p2.object_id) AS object_id , COALESCE(p1.index_id, p2.index_id) AS index_id , bd.row_count, bd.free_space_in_bytes, CONVERT(TINYINT,bd.is_modified) AS 'DirtyPage' FROM sys.dm_os_buffer_descriptors AS bd JOIN sys.allocation_units AS au ON au.allocation_unit_id = bd.allocation_unit_id OUTER APPLY ( SELECT TOP(1) p.object_id, p.index_id FROM sys.partitions AS p WHERE p.hobt_id = au.container_id AND au.type IN (1, 3) ) AS p1 OUTER APPLY ( SELECT TOP(1) p.object_id, p.index_id FROM sys.partitions AS p WHERE p.partition_id = au.container_id AND au.type = 2 ) AS p2 WHERE  bd.database_id = DB_ID() AND bd.page_type IN ('DATA_PAGE', 'INDEX_PAGE') ) SELECT TOP 20 DB_NAME(database_id) AS 'Database',OBJECT_NAME(object_id,database_id) AS 'Table Name', index_id,COUNT(*) AS 'Pages in Cache', SUM(dirtyPage) AS 'Dirty Pages' FROM memusage_CTE GROUP BY database_id, object_id, index_id ORDER BY COUNT(*) DESC I’m not 100% happy with the results of the above query however… I’ve noticed that on a busy BizTalk messageBox database  it will return information on pages that contain GHOST rows – . ie where data has already been deleted but has yet to be cleaned-up by a background process – I’m need to investigate further why cache on this server apparently contains so much GHOST data… For more information on the background ghost cleanup process, see this article by Paul Randall. However, I think the results of this query should still be of interest to a DBA. I have another post to come shortly regarding an example I encountered where this information proved useful to me… I notice in SQL 2008, sys.dm_os_buffer_descriptors gained an extra column – numa_mode – I’m interested to see how this is populated and how useful this column can be on a NUMA-enabled system. I’m assuming in theory you could use this column to help analyse how your tables are spread across Numa-enabled data-cache ?

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• Be Careful When Referencing SPList.Items

  - by Brian Jackett

  Be very careful how you reference your SPListItem objects through the SharePoint API.  I’ll say it again.  Be very careful how you reference your SPListItem objects through the SharePoint API.  Ok, now that you get the point that this will be a “learn from my mistakes and don’t do unsmart things like I did” post, let’s dig into what it was that I did poorly. Scenario     For the past year I’ve been building custom .Net applications that are hosted through SharePoint.  These application involve a number of SharePoint lists, external databases, custom web parts, and other SharePoint elements to provide functionality.  About two weeks ago I received a message from one of our end users that a custom application was performing slowly.  Specifically performance was slow when users were performing actions that interacted with the primary SharePoint list storing data for that app. The Problem     I took a copy of the production site into a dev environment to investigate the code that was executing.  After attaching the debugger and running through the code I quickly found pieces of code referencing SPListItem objects (like below) that were performing very poorly: SPListItem myItem = SPContext.Current.Web.Lists["List Name"].Items.GetItemById(value); // do updates on SPListItem retrieved     As it turns out the SPList I was referencing was fairly large at ~1000 items and weighing in over 150 MB.  You see the problem with my above code is that I retrieved the SPListItem by first (unnecessarily) going through the Items member of the list.  As I understand it, when doing so the executing code will attempt to resolve that entity and pull it from the database and into RAM (all 150 MB.)  This causes the equivalent of a 50 car pile up in terms of performance with a single update taking more than 15 seconds. The Solution     The solution is actually quite simple and I wish I had realized this during development.  Instead of going through the Items member it is possible to call GetItemById(…) directly on the SPList as in the example below: SPListItem myItem = SPContext.Current.Web.Lists["List Name"].GetItemById(value); // do updates on SPListItem retrieved     After making this simple change performance skyrocketed and updates were back to less than a second.   Conclusion     When given the option between two solutions, usually the simplest is the best solution.  In my scenario I was adding extra complexity going through the API the long way around to get to the objects I needed and it ended up hurting performance greatly.  Luckily we were able to find and resolve the performance issue in a relatively short amount of time.  Like I said at the beginning of the post, learn from my mistakes and hope it helps you.         -Frog Out   Image linked from http://www.freespirit.com/files/IMAGE/COVER/LARGE/BeCarefulSafe.jpg

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• Dart and NetBeans IDE 7.4

  - by Geertjan

  Here's the start of Dart in NetBeans IDE. Basic Dart editing support is done and on saving a Dart file the related JavaScript files are automatically generated. In the context of an HTML5 application in NetBeans IDE, that gives you deep integration with the embedded browser and, even better, Chrome, as well as Chrome Developer Tools. Below, notice that the "Sunflower Spectacular" H1 element is selected (click the image to enlarge it to get a better view), which is therefore highlighted in the live DOM view in the bottom left, as well as in the CSS Styles window in the top right, from where the CSS styles can be edited and from where the related files can be opened in the IDE. Identical features are available for Chrome, as well as on Android and iOS. And if you like that, watch this YouTube movie showing how Chrome Developer Tools integration can fit directly into the workflow below. Anyone want to help get this plugin further? What's needed: Much deeper Dart editing support, i.e., right now only very basic syntax coloring is provided, i.e., an ANTLR lexer is integrated into the NetBeans syntax coloring infrastructure. Parsing, error checking, code completion, and some small code templates are needed. A new panel is needed in the Project Properties dialog on NetBeans HTML5 projects for enabling Dart (i.e., similar to enabling Cordova), at which point the "dart.js" file and other Dart artifacts should be added to the project, so that a Dart project is immediately generated and the application should be immediately deployable. Whenever changes are made to a Dart file, Dart should run in the background to create the Dart artifacts in some hidden way, so that the user doesn't see all the Dart artifacts as is currently the case. Some way of recognizing Dart projects (there's a YAML file as an identifier) and creating NetBeans HTML5 projects from that, i.e., from Dart projects outside the IDE. I think that's all... The official Dart Editor is based on Eclipse and requires a massive download of heaps of Eclipse bundles. Compare that to the NetBeans equivalent, which is a very small "HTML5 and PHP" bundle (60 MB), available here, together with the above small Dart plugin. Plus, when you look at how NetBeans IDE integrates with a bunch of Google-oriented projects, i.e., Chrome, Chrome Developer Tools, and Android (via Cordova), that's a pretty interesting toolbox for anyone using Dart. And bear in mind that ANTLRWorks, Microchip, and heaps of other organizations have built and are building their tools on top of NetBeans!

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• Naming Convention for Dedicated Thread Locking objects

  - by Chris Sinclair

  A relatively minor question, but I haven't been able to find official documentation or even blog opinion/discussions on it. Simply put: when I have a private object whose sole purpose is to serve for private lock, what do I name that object? class MyClass { private object LockingObject = new object(); void DoSomething() { lock(LockingObject) { //do something } } } What should we name LockingObject here? Also consider not just the name of the variable but how it looks in-code when locking. I've seen various examples, but seemingly no solid go-to advice: Plenty of usages of SyncRoot (and variations such as _syncRoot). Code Sample: lock(SyncRoot), lock(_syncRoot) This appears to be influenced by VB's equivalent SyncLock statement, the SyncRoot property that exists on some of the ICollection classes and part of some kind of SyncRoot design pattern (which arguably is a bad idea) Being in a C# context, not sure if I'd want to have a VBish naming. Even worse, in VB naming the variable the same as the keyword. Not sure if this would be a source of confusion or not. thisLock and lockThis from the MSDN articles: C# lock Statement, VB SyncLock Statement Code Sample: lock(thisLock), lock(lockThis) Not sure if these were named minimally purely for the example or not Kind of weird if we're using this within a static class/method. Several usages of PadLock (of varying casing) Code Sample: lock(PadLock), lock(padlock) Not bad, but my only beef is it unsurprisingly invokes the image of a physical "padlock" which I tend to not associate with the abstract threading concept. Naming the lock based on what it's intending to lock Code Sample: lock(messagesLock), lock(DictionaryLock), lock(commandQueueLock) In the VB SyncRoot MSDN page example, it has a simpleMessageList example with a private messagesLock object I don't think it's a good idea to name the lock against the type you're locking around ("DictionaryLock") as that's an implementation detail that may change. I prefer naming around the concept/object you're locking ("messagesLock" or "commandQueueLock") Interestingly, I very rarely see this naming convention for locking objects in code samples online or on StackOverflow. Question: What's your opinion generally about naming private locking objects? Recently, I've started naming them ThreadLock (so kinda like option 3), but I'm finding myself questioning that name. I'm frequently using this locking pattern (in the code sample provided above) throughout my applications so I thought it might make sense to get a more professional opinion/discussion about a solid naming convention for them. Thanks!

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• Subterranean IL: Exception handler semantics

  - by Simon Cooper

  In my blog posts on fault and filter exception handlers, I said that the same behaviour could be replicated using normal catch blocks. Well, that isn't entirely true... Changing the handler semantics Consider the following: .try { .try { .try { newobj instance void [mscorlib]System.Exception::.ctor() // IL for: // e.Data.Add("DictKey", true) throw } fault { ldstr "1: Fault handler" call void [mscorlib]System.Console::WriteLine(string) endfault } } filter { ldstr "2a: Filter logic" call void [mscorlib]System.Console::WriteLine(string) // IL for: // (bool)((Exception)e).Data["DictKey"] endfilter }{ ldstr "2b: Filter handler" call void [mscorlib]System.Console::WriteLine(string) leave.s Return } } catch object { ldstr "3: Catch handler" call void [mscorlib]System.Console::WriteLine(string) leave.s Return } Return: // rest of method If the filter handler is engaged (true is inserted into the exception dictionary) then the filter handler gets engaged, and the following gets printed to the console: 2a: Filter logic 1: Fault handler 2b: Filter handler and if the filter handler isn't engaged, then the following is printed: 2a:Filter logic 1: Fault handler 3: Catch handler Filter handler execution The filter handler is executed first. Hmm, ok. Well, what happens if we replaced the fault block with the C# equivalent (with the exception dictionary value set to false)? .try { // throw exception } catch object { ldstr "1: Fault handler" call void [mscorlib]System.Console::WriteLine(string) rethrow } we get this: 1: Fault handler 2a: Filter logic 3: Catch handler The fault handler is executed first, instead of the filter block. Eh? This change in behaviour is due to the way the CLR searches for exception handlers. When an exception is thrown, the CLR stops execution of the thread, and searches up the stack for an exception handler that can handle the exception and stop it propagating further - catch or filter handlers. It checks the type clause of catch clauses, and executes the code in filter blocks to see if the filter can handle the exception. When the CLR finds a valid handler, it saves the handler's location, then goes back to where the exception was thrown and executes fault and finally blocks between there and the handler location, discarding stack frames in the process, until it reaches the handler. So? By replacing a fault with a catch, we have changed the semantics of when the filter code is executed; by using a rethrow instruction, we've split up the exception handler search into two - one search to find the first catch, then a second when the rethrow instruction is encountered. This is only really obvious when mixing C# exception handlers with fault or filter handlers, so this doesn't affect code written only in C#. However it could cause some subtle and hard-to-debug effects with object initialization and ordering when using and calling code written in a language that can compile fault and filter handlers.

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• Running Multiple Queries in Oracle SQL Developer

  - by thatjeffsmith

  There are two methods for running queries in SQL Developer: Run Statement Run Statement, Shift+Enter, F9, or this button Run Script No grids, just script (SQL*Plus like) ouput is fine, thank you very much! What’s the Difference? There are some obvious differences between the two features, the most obvious being the format of the output delivered. But there are some other, more subtle differences here, primarily around fetching. What is Fetch? After you run send your query to Oracle, it has to do 3 things: Parse Execute Fetch Technically it has to do at least 2 things, and sometimes only 1. But, to get the data back to the user, the fetch must occur. If you have a 10 row query or a 1,000,000 row query, this can mean 1 or many fetches in groups of records. Ok, before I went on the Fetch tangent, I said there were two ways to run statements in SQL Developer: Run Statement Run statement brings your query results to a grid with a single fetch. The user sees 50, 100, 500, etc rows come back, but SQL Developer and the database know that there are more rows waiting to be retrieved. The process on the server that was used to execute the query is still hanging around too. To alleviate this, increase your fetch size to 500. Every query ran will come back with the first 500 rows, and rows will be continued to be fetched in 500 row increments. You’ll then see most of your ad hoc queries complete with a single fetch. Scroll down, or hit Ctrl+End to force a full fetch and get all your rows back. Run Script Run Script runs the contents of the worksheet (or what’s highlighted) as a ‘script.’ What does that mean exactly? Think of this as being equivalent to running this in SQL*Plus: @my_script.sql; Each statement is executed. Also, ALL rows are fetched. So once it’s finished executing, there are no open cursors left around. The more obvious difference here is that the output comes back formatted as plain old text. Run one or more commands plus SQL*Plus commands like SET and SPOOL The Trick: Run Statement Works With Multiple Statements! It says ‘run statement,’ but if you select more than one with your mouse and hit the button – it will run each and throw the results to 1 grid for each statement. If you mouse hover over the Query Result panel tab, SQL Developer will tell you the query used to populate that grid. This will work regardless of what you have this preference set to: DATABASE – WORKSHEET – SHOW QUERY RESULTS IN NEW TABS Mind the fetch though! Close those cursors by bring back all the records or closing the grids when you’re done with them.

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• Programming and Ubiquitous Language (DDD) in a non-English domain

  - by Sandor Drieënhuizen

  I know there are some questions already here that are closely related to this subject but none of them take Ubiquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with mixed languages anyway. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options? UPDATE Today, about year later, having dealt with this issue on a daily basis, I have to say that option 3 has worked out pretty well for me. It wasn't as tedious as I initially feared and translating in real time while talking to the client wasn't a problem either. I also found the following advantages to be true, based on my experience. Translating the UL makes you pay more attention to defining the UL and even the domain itself, especially when you don't know how to translate a term and you have to start looking through dictionaries etc. This has even caused me to reconsider domain modeling decisions a few times. It helps you make your knowledge of the English language more profound. Obviously, your code is much more pleasant to look at instead of being a mind boggling obscenity.

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• Patterns for Handling Changing Property Sets in C++

  - by Bhargav Bhat

  I have a bunch "Property Sets" (which are simple structs containing POD members). I'd like to modify these property sets (eg: add a new member) at run time so that the definition of the property sets can be externalized and the code itself can be re-used with multiple versions/types of property sets with minimal/no changes. For example, a property set could look like this: struct PropSetA { bool activeFlag; int processingCount; /* snip few other such fields*/ }; But instead of setting its definition in stone at compile time, I'd like to create it dynamically at run time. Something like: class PropSet propSetA; propSetA("activeFlag",true); //overloading the function call operator propSetA("processingCount",0); And the code dependent on the property sets (possibly in some other library) will use the data like so: bool actvFlag = propSet["activeFlag"]; if(actvFlag == true) { //Do Stuff } The current implementation behind all of this is as follows: class PropValue { public: // Variant like class for holding multiple data-types // overloaded Conversion operator. Eg: operator bool() { return (baseType == BOOLEAN) ? this->ToBoolean() : false; } // And a method to create PropValues various base datatypes static FromBool(bool baseValue); }; class PropSet { public: // overloaded[] operator for adding properties void operator()(std::string propName, bool propVal) { propMap.insert(std::make_pair(propName, PropVal::FromBool(propVal))); } protected: // the property map std::map<std::string, PropValue> propMap; }; This problem at hand is similar to this question on SO and the current approach (described above) is based on this answer. But as noted over at SO this is more of a hack than a proper solution. The fundamental issues that I have with this approach are as follows: Extending this for supporting new types will require significant code change. At the bare minimum overloaded operators need to be extended to support the new type. Supporting complex properties (eg: struct containing struct) is tricky. Supporting a reference mechanism (needed for an optimization of not duplicating identical property sets) is tricky. This also applies to supporting pointers and multi-dimensional arrays in general. Are there any known patterns for dealing with this scenario? Essentially, I'm looking for the equivalent of the visitor pattern, but for extending class properties rather than methods. Edit: Modified problem statement for clarity and added some more code from current implementation.

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• Aptronyms: fitting the profession to the name

  - by Tony Davis

  Writing a recent piece on the pains of index fragmentation, I found myself wondering why, in SQL Server, you can’t set the equivalent of a fill factor, on a heap table. I scratched my head…who might know? Phil Factor, of course! I approached him with a due sense of optimism only to find that not only did he not know, he also didn’t seem to care much either. I skulked off thinking how this may be the final nail in the coffin of nominative determinism. I’ve always wondered if there was anything in it, though. If your surname is Plumb or Leeks, is there even a tiny, extra percentage chance that you’ll end up fitting bathrooms? Some examples are quite common. I’m sure we’ve all met teachers called English or French, or lawyers called Judge or Laws. I’ve also known a Doctor called Coffin, a Urologist called Waterfall, and a Dentist called Dentith. Two personal favorites are Wolfgang Wolf who ended up managing the German Soccer team, Wolfsburg, and Edmund Akenhead, a Crossword Editor for The Times newspaper. Having forgiven Phil his earlier offhandedness, I asked him for if he knew of any notable examples. He had met the famous Dr. Batty and Dr. Nutter, both Psychiatrists, knew undertakers called Death and Stiff, had read a book by Frederick Page-Turner, and suppressed a giggle at the idea of a feminist called Gurley-Brown. He even managed to better my Urologist example, citing the article on incontinence in the British Journal of Urology (vol.49, pp.173-176, 1977) by A. J. Splatt and D. Weedon. What, however, if you were keen to gently nudge your child down the path to a career in IT? What name would you choose? Subtlety probably doesn’t really work, although in a recent interview, Rodney Landrum did congratulate PowerShell MVP Max Trinidad on being named after a SQL function. Grant “The Memory” Fritchey (OK, I made up that nickname) doesn’t do badly either. Some surnames, seem to offer a natural head start, although I know of no members of the Page-Reid clan in the profession. There are certainly families with the Table surname, although sadly, Little Bobby Tables was merely a legend by xkcd. A member of the well-known Key family would need to name their son Primary, or maybe live abroad, to make their mark. Nominate your examples of people seemingly destined, by name, for their chosen profession (extra points for IT). The best three will receive a prize. Cheers, Tony.

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• Configuring Touchpad Multi-Tap on Ubuntu 11.10

  - by nunos

  I am having a hard time configuring my notebook's touchpad. I can do everything I can in Windows with the exception of three-finger tap, which doesn't work, and the action of two-finger tap which is giving me the equivalent to a right-mouse click, when I wanted a middle-mouse click. I read on a forum to use this as a guide. The problem is that I can't even find the configuration file /etc/X11/xorg.conf.d/10-synaptics.conf. I tried running pacman -S xf86-input-synaptics but I don't have the pacman program installed. When I try to install it by sudo apt-get install I get a pacman game instead! I know the guide is for archlinux, so maybe that's why it doesn't work with me. I am running Ubuntu 11.10 on an Asus N82JV. Any help on this is appreciated. Here's the output of xinput list: nuno@mozart:~$ xinput list ? Virtual core pointer id=2 [master pointer (3)] ? ? Virtual core XTEST pointer id=4 [slave pointer (2)] ? ? Microsoft Microsoft® Nano Transceiver v2.0 id=12 [slave pointer (2)] ? ? Microsoft Microsoft® Nano Transceiver v2.0 id=13 [slave pointer (2)] ? ? ETPS/2 Elantech Touchpad id=16 [slave pointer (2)] ? Virtual core keyboard id=3 [master keyboard (2)] ? Virtual core XTEST keyboard id=5 [slave keyboard (3)] ? Power Button id=6 [slave keyboard (3)] ? Video Bus id=7 [slave keyboard (3)] ? Video Bus id=8 [slave keyboard (3)] ? Sleep Button id=9 [slave keyboard (3)] ? USB2.0 2.0M UVC WebCam id=10 [slave keyboard (3)] ? Microsoft Microsoft® Nano Transceiver v2.0 id=11 [slave keyboard (3)] ? Asus Laptop extra buttons id=14 [slave keyboard (3)] ? AT Translated Set 2 keyboard id=15 [slave keyboard (3)]

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• Great opportunity to try Windows Azure over the next 7 days if you are a UK developer &ndash; act to

  - by Eric Nelson

  Are you a UK based developer who has been put off from trying out the Windows Azure Platform? Were you concerned that you needed to hand over credit card details even to use the introductory offer? Or concerned about how many charges you might run up as you played with “elastic computing”. Then we might have just what you need. 7 Days of access to the Windows Azure Platform – for FREE (expires June 6th 2010) If you are accepted, you will be given a Windows Azure Platfom subscription that will enable you to create Windows Azure hosted services and storage accounts, SQL Azure databases and AppFabric services without any fear of being charged between now and Sunday the 6th of June 2010. No credit card is required. Important: At the end of Sunday your subscription and all your code and data you have uploaded will be deleted. It is your responsibility to keep local copies of your code and data. Apply now To apply for this offer you need to: email ukdev AT microsoft.com with a subject line that starts “UKAZURETRAIL:” (This must  be present) In the email you need to demonstrate you are UK based (.uk email alias or address or… be creative) And you must include 30 to 100 words explaining What your interest is in the Windows Azure Platform and Cloud Computing What you would use the 7 days to explore Some notes (please read!): We have a limited number of these offers to give away on a first come, first served basis (subject to meeting the above criteria). We plan to process all request asap – but there is a UK bank holiday weekend looming. We will do our best to process all by Tues afternoon (which would still give you 5 days of access) There will be no specific support for this offer. We will not be processing any requests that arrive after Tuesday 1st. In case you were wondering, there is no equivalent offer for developer outside of the UK. This offer is a direct result of UK based training we are currently doing which has some spare Azure capacity which we wanted to make best use of. Sorry in advance if you based outside of the UK. Related Links: If you are UK based, you should also join the UK Windows Azure Platform community http://ukazure.ning.com Microsoft UK Windows Azure Platform page

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• Database Mirroring – deprecated

  - by fatherjack

  Do you use mirroring on any of your databases? Do you use mirroring on SQL Server Standard Edition? I do, as a way of having a stand-by server ready to take over if there is a problem with the live server so that business can continue despite whatever disaster may strike at our primary server location. In my experience it has been a great solution for us as it is simple to implement, reliable and predictable. Mirroring has been around since SQL Server 2005 sp1 but with the release of SQL Server 2012 mirroring has now been placed on the deprecation list. That’s right, Microsoft are removing this feature from SQL Server. SQL Server 2012 had lots of improvements and new features around this sort of technology – the High Availability, Disaster recovery and Always On features described in detail here by Brent Ozar and  Microsoft’s own Customer Service and Support SQL Server Engineers . Now the bad news, the HADRON features are pretty much all wrapped up in the Enterprise Edition of SQL Server 2012. This is going to be a big issue for people, like me, who are only on Standard Edition of earlier versions mostly due to our requirements and the budget (or lack thereof) required for Enterprise Edition licenses. No mirroring in Standard Edition means no upgrade. Don’t Panic. There are two stages of deprecation and they dont happen fast. The first stage – Deprecation Announcement- means that Microsoft have decided that there is a limited future for a particular feature and this is your cue that new projects and developments should not be implemented on this technology as it will cease to exist in the future. This is where mirroring currently stands. You have time to consider your options and start work on planning how you will move away from using this feature. This can be 2 or 3 versions of SQL Server, possibly more. The next stage is Deprecation Final Support - this is where you are on your last chance, When you see this then the next version of SQL Server will not have this feature in it so you need to implement your plans to move to an alternative solution. While these two phases are taking place Microsoft are open to feedback on how people use their products and if enough people make the case for mirroring (or an equivalent technology) to be in the Standard Edition then they may make changes rather than lose customers or have customers cease upgrading in order to keep the functionality they need. Denny Cherry (@MrDenny) has published an article on this same topic here with more detail than me so I wont go over old ground. All I will say is that you should read his article now and then follow the link to his own site where he is collecting peoples information on how they use mirroring in Standard Edition so that our voice can be put to Microsoft.  

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• How to join two collections with LINQ

  - by JustinGreenwood

  Here is a simple and complete example of how to perform joins on two collections with LINQ. I wrote it for a friend to show him, in one simple file, the power of LINQ queries and anonymous objects. In the file below, there are two simple data classes defined: Person and Item. In the beginning of the main method, two collections are created. Note that the Item's OwnerId field reference the PersonId of a Person object. The effect of the LINQ query below is equivalent to a SQL statement looking like this: select Person.PersonName as OwnerName, Item.ItemName as OwnedItem from Person inner join Item on Item.OwnerId = Person.PersonId order by Item.ItemName desc; using System; using System.Collections.Generic; using System.Linq; namespace LinqJoinAnonymousObjects { class Program { class Person { public int PersonId { get; set; } public string PersonName { get; set; } } class Item { public string ItemName { get; set; } public int OwnerId { get; set; } } static void Main(string[] args) { // Create two collections: one of people, and another with their possessions. var people = new List<Person> { new Person { PersonId=1, PersonName="Justin" }, new Person { PersonId=2, PersonName="Arthur" }, new Person { PersonId=3, PersonName="Bob" } }; var items = new List<Item> { new Item { OwnerId=1, ItemName="Armor" }, new Item { OwnerId=1, ItemName="Book" }, new Item { OwnerId=2, ItemName="Chain Mail" }, new Item { OwnerId=2, ItemName="Excalibur" }, new Item { OwnerId=3, ItemName="Bubbles" }, new Item { OwnerId=3, ItemName="Gold" } }; // Create a new, anonymous composite result for person id=2. var compositeResult = from p in people join i in items on p.PersonId equals i.OwnerId where p.PersonId == 2 orderby i.ItemName descending select new { OwnerName = p.PersonName, OwnedItem = i.ItemName }; // The query doesn't evaluate until you iterate through the query or convert it to a list Console.WriteLine("[" + compositeResult.GetType().Name + "]"); // Convert to a list and loop through it. var compositeList = compositeResult.ToList(); Console.WriteLine("[" + compositeList.GetType().Name + "]"); foreach (var o in compositeList) { Console.WriteLine("\t[" + o.GetType().Name + "] " + o.OwnerName + " - " + o.OwnedItem); } Console.ReadKey(); } } } The output of the program is below: [WhereSelectEnumerableIterator`2] [List`1] [<>f__AnonymousType1`2] Arthur - Excalibur [<>f__AnonymousType1`2] Arthur - Chain Mail

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• Basis of definitions

  - by Yttrill

  Let us suppose we have a set of functions which characterise something: in the OO world methods characterising a type. In mathematics these are propositions and we have two kinds: axioms and lemmas. Axioms are assumptions, lemmas are easily derived from them. In C++ axioms are pure virtual functions. Here's the problem: there's more than one way to axiomatise a system. Given a set of propositions or methods, a subset of the propositions which is necessary and sufficient to derive all the others is called a basis. So too, for methods or functions, we have a desired set which must be defined, and typically every one has one or more definitions in terms of the others, and we require the programmer to provide instance definitions which are sufficient to allow all the others to be defined, and, if there is an overspecification, then it is consistent. Let me give an example (in Felix, Haskell code would be similar): class Eq[t] { virtual fun ==(x:t,y:t):bool => eq(x,y); virtual fun eq(x:t, y:t)=> x == y; virtual fun != (x:t,y:t):bool => not (x == y); axiom reflex(x:t): x == x; axiom sym(x:t, y:t): (x == y) == (y == x); axiom trans(x:t, y:t, z:t): implies(x == y and y == z, x == z); } Here it is clear: the programmer must define either == or eq or both. If both are defined, the definitions must be equivalent. Failing to define one doesn't cause a compiler error, it causes an infinite loop at run time. Defining both inequivalently doesn't cause an error either, it is just inconsistent. Note the axioms specified constrain the semantics of any definition. Given a definition of == either directly or via a definition of eq, then != is defined automatically, although the programmer might replace the default with something more efficient, clearly such an overspecification has to be consistent. Please note, == could also be defined in terms of !=, but we didn't do that. A characterisation of a partial or total order is more complex. It is much more demanding since there is a combinatorial explosion of possible bases. There is an reason to desire overspecification: performance. There also another reason: choice and convenience. So here, there are several questions: one is how to check semantics are obeyed and I am not looking for an answer here (way too hard!). The other question is: How can we specify, and check, that an instance provides at least a basis? And a much harder question: how can we provide several default definitions which depend on the basis chosen?

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• Partial Submit vs. Auto Submit

  - by Frank Nimphius

  Partial Submit ADF Faces adds the concept of partial form submit to JavaServer Faces 1.2 and beyond. A partial submit actually is a form submit that does not require a page refresh and only updates components in the view that are referenced from the command component PartialTriggers property. Another option for refreshing a component in response to a partial submit is call AdfContext.getCurrentInstance.addPartialTarget(component_instance_handle_goes_here)in a managed bean. If a form contains required fields that the user left empty invoking the partial submit, then errors are shown for each of the field as the full form gets submitted. Autosubmit An input component that has its autosubmit property set to true also performs a partial submit of the form. However, this time it doesn't submit the entire form but only the component that triggers the submit plus components referenced it in their PartialTriggers property. For example, consider a form that has three input fields inpA, inpB and inpC with autosubmit=true set on inpA and required=true set on inpB and inpC. use case 1: Running the view, entering data into inpA and then tabbing out of the field will submit the content for inpA but not for inpB and inpC. Further more, none of the required field settings on inpB and inpC causes an error. use case 2: You change the configuration of inpC and set its PartialTriggers property to point to the ID of component inpA. When rerunning the sample, entering a value into inpA and tabbing out of the field will now submit the inpA and inpC fields and thus show an error for the missing required value on inpC. Internally, using autosubmit=true on an input component sets the event root to just this field, which good to have in case of dependent field validation or behavior. The event root can extended to include other components by using the Partial Triggers property on these components to point to the input field that has autosubmit=true defined. PartialSubmit vs. AutoSubmit Partial submit set on a command component submits the whole form and leaves it to the developer to decide which UI component is refreshed in response. Client side required field validation (as well as the server side equivalent) is not disabled by executed in this scenario. Setting immediate=true on the command item to skip validation doesn't help as it would also skip the model update. Auto submit is a functionality on the input components and also performs a partial form submit. However, in addition an event root is defined that narrows the scope for the submitted data and thus the components that are validated on the request. To read more about this topic, see: http://docs.oracle.com/cd/E23943_01/web.1111/b31973/af_lifecycle.htm#CIAHCFJF

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• Sometimes keyboard & touchpad work... sometimes not

  - by Voyagerfan5761

  When I first ran Ubuntu from CD on this Dell Inspiron 2650, it worked for about ten to fifteen minutes, then it hung (I was probably trying to do too much at once from a Live CD). The next time, my mouse and keyboard didn't work. I rebooted three times and finally got them working. I then installed Ubuntu alongside Windows XP. After installing, selecting the OS in GRUB worked, but my touchpad and keyboard were again not working. I rebooted, and they worked. (I fortunately had a USB mouse with which to reboot.) Booting Ubuntu and then rebooting to enable my keyboard and touchpad has become a routine ever since. Often several reboots are required; at one point I had to reboot over a dozen times in a row before getting a session where everything worked properly. (My installation has been in place for about three days a week now.) I've looked around for a device manager equivalent to no avail. Sometimes the hardware is properly detected, and sometimes it's not. Once or twice I've had the keyboard detected properly but the touchpad not. Plugging in my wireless card also sometimes requires a plug, unplug, and plug again to get it working. So is there some solution? I'm without an Internet connection at home, and this "laptop" is really a wall wart on my desk, so suggestions for packages may take a while to test. Xorg logs I captured two three four sample Xorg logs: one from a startup where the devices worked; one from when they didn't; one from a session where Ubuntu thought my touchpad was a normal mouse; and one from a session where my keyboard worked but the touchpad didn't. See this gist. Updated 2010-12-15 01:50 UTC with Xorg.0.log.keyboardonly file illustrating the case where the keyboard worked but not the touchpad. Updated 2011-01-11 04:10 UTC with Xorg.0.log.touchpadregmouse to illustrate a case where the touchpad was detected as a regular mouse (no "Touchpad" tab in mouse prefs).

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• Learn programming backwards, or "so I failed the FizzBuzz test. Now what?"

  - by moraleida

  A Little Background I'm 28 today, and I've never had any formal training in software development, but I do have two higher education degrees equivalent to a B.A in Public Relations and an Executive MBA focused on Project Management. I've worked on those fields for about 6 years total an then, 2,5 years ago I quit/lost my job and decided to shift directions. After a month thinking things through I decided to start freelancing developing small websites in WordPress. I self-learned my way into it and today I can say I run a humble but successful career developing themes and plugins from scratch for my clients - mostly agencies outsourcing some of their dev work for medium/large websites. But sometimes I just feel that not having studied enough math, or not having a formal understanding of things really holds me behind when I have to compete or work with more experienced developers. I'm constantly looking for ways to learn more but I seem to lack the basics. Unfortunately, spending 4 more years in Computer Science is not an option right now, so I'm trying to learn all I can from books and online resources. This method is never going to have NASA employ me but I really don't care right now. My goal is to first pass the bar and to be able to call myself a real programmer. I'm currently spending my spare time studying Java For Programmers (to get a hold on a language everyone says is difficult/demanding), reading excerpts of Code Complete (to get hold of best practices) and also Code: The Hidden Language of Computer Hardware and Software (to grasp the inner workings of computers). TL;DR So, my current situation is this: I'm basically capable of writing any complete system in PHP (with the help of Google and a few books), integrating Ajax, SQL and whatnot, and maybe a little slower than an experienced dev would expect due to all the research involved. But I was stranded yesterday trying to figure out (not Google) a solution for the FizzBuzz test because I didn't have the if($n1 % $n2 == 0) method modulus operator memorized. What would you suggest as a good way to solve this dilemma? What subjects/books should I study that would get me solving problems faster and maybe more "in a programmers way"? EDIT - Seems that there was some confusion about what did I not know to solve FizzBuzz. Maybe I didn't express myself right: I knew the steps needed to solve the problem. What I didn't memorize was the modulus operator. The problem was in transposing basic math to the program, not in knowing basic math. I took the test for fun, after reading about it on Coding Horror. I just decided it was a good base-comparison line between me and formally-trained devs. I just used this as an example of how not having dealt with math in a computer environment before makes me lose time looking up basic things like modulus operators to be able to solve simple problems.

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• How to detect browser type and version from ADF Faces

  - 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;} Sometimes ADF applications need to know about the user browser type and version. For this, assuming you need this information in Java, you can use the Trinidad RequestContext object. You could also use the AdfFacesContext object for the same, but since the ADF Faces Agent class is marked as deprecated, using the equivalent Trinidad classes is the better choice. The source code below prints the user browser information to the Oracle JDeveloper message window import org.apache.myfaces.trinidad.context.Agent; import org.apache.myfaces.trinidad.context.RequestContext; … RequestContext requestCtx = RequestContext.getCurrentInstance(); Agent agent = requestCtx.getAgent(); String version = agent.getAgentVersion(); String browser = agent.getAgentName(); String platform = agent.getPlatformName(); String platformVersion = agent.getPlatformVersion(); System.out.println("=================="); System.out.println("Your browser information: "); System.out.println("Browser: "+browser); System.out.println("Browser Version : "+version); System.out.println("Browser Platform: "+platform); System.out.println("Browser Platform Version: "+platformVersion); System.out.println("==================");

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• Will Online Learning Save Higher Education (and does it need saving)?

  - by user739873

  A lot (an awful lot) of education industry rag real estate has been devoted to the topics of online learning, MOOC’s, Udacity, edX, etc., etc. and to the uninitiated you’d think that the education equivalent of the cure for cancer had been discovered. There are certainly skeptics (whose voice is usually swiftly trampled upon by the masses) who feel we could over steer and damage or destroy something vital to teaching and learning (i.e. the classroom experience and direct interaction with human beings known as instructors), but for the most part prevailing opinion seems to be that online learning will take over the world and that higher education will never be the same. Now I’m sure that since you all know I work for a technology company you think I’m going to come down hard on the side of online learning proselytizers. Yes, I do believe that this revolution can and will provide access to massive numbers of individuals that either couldn’t afford (from a fiscal or time perspective) a traditional education, and that in some cases the online modality will actually be an improvement over certain traditional forms (such as courses taught by an adjunct or teaching assistant that has no business being a teacher). But I think several things need immediate attention or we’re likely to get so caught up in the delivery that we miss some of the real issues (and opportunities) around online learning. First and foremost, we’ve got to give some thought to how traditional information systems are going to accommodate thousands (possibly hundreds of thousands) of individual students each taking courses from many, many different “deliverers” with an expectation that successful completion of these courses will result in credit at many or most institutions. There’s also a huge opportunity to refine the delivery platform (no, LMS is not a commodity when you are talking about online delivery being your sole mode of operation) as well as the course itself by mining all kinds of data from the interactions that the students have with the material each time they take it. Social data analytics tools will be key in achieving this goal. What about accreditation (badging or competencies vs. traditional degrees)? And again, will the information systems in place today adapt to changes in this area fast enough? The type of scale that this shift in learning could drive has the potential to abruptly overwhelm just about every system in place today in higher education. I would like to (with a not so gentle reminder) refer you back to a blog entry I wrote when I first stepped into my current role at Oracle in which I talked about how higher ed needs an “Oracle” more than at any other time in it’s evolution (despite the somewhat mercantilist reputation it has in some circles). There just aren’t that many organizations that can deliver the kinds of solutions “at scale” that this brave new world of online education will demand. The future may be closer than we think. Cole

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• Wireframing: A Day In the Life of UX Workshop at Oracle

  - by ultan o'broin

  The Oracle Applications User Experience team's Day in the Life (DITL) of User Experience (UX) event was run in Oracle's Redwood Shores HQ for Oracle Usability Advisory Board (OUAB) members. I was charged with putting together a wireframing session, together with Director of Financial Applications User Experience, Scott Robinson (@scottrobinson). Example of stunning new wireframing visuals we used on the DITL events. We put on a lively show, explaining the basics of wireframing, the concepts, what it is and isn't, considerations on wireframing tool choice, and then imparting some tips and best practices. But the real energy came when the OUAB customers and partners in the room were challenge to do some wireframing of their own. Wireframing is about bringing your business and product use cases to life in real UX visual terms, by creating a low-fidelity drawing to iterate and agree on in advance of prototyping and coding what is to be finally built and rolled out for users. All the best people wireframe. Leonardo da Vinci used "cartoons" on some great works, tracing outlines first and using red ochre or charcoal dropped through holes in the tracing parchment onto the canvas to outline the subject. (Image distributed under Wikimedia commons license) Wireframing an application's user experience design enables you to: Obtain stakeholder buy-in. Enable faster iteration of different designs. Determine the task flow navigation paths (in Oracle Fusion Applications navigation is linked with user roles). Develop a content strategy (readability, search engine optimization (SEO) of content, and so on) Lay out the pages, widgets, groups of features, and so on. Apply usability heuristics early (no replacement for usability testing, but a great way to do some heavy-lifting up front). Decide upstream which functional user experience design patterns to apply (out of the box solutions that expedite productivity). Assess which Oracle Application Development Framework (ADF) or equivalent technology components can be used (again, developer productivity is enhanced downstream). We ran a lively hands-on exercise where teams wireframed a choice of application scenarios using the time-honored tools of pen and paper. Scott worked the floor like a pro, pointing out great use of features, best practices, innovations, and making sure that the whole concept of wireframing, the gestalt, transferred. "We need more buttons!" The cry of the energized. Not quite. The winning wireframe session (online shopping scenario) from the Applications UX DITL event shown. Great fun, great energy, and great teamwork were evident in the room. Naturally, there were prizes for the best wireframe. Well, actually, prizes were handed out to the other attendees too! An exciting, slightly different aspect to delivery of this session made the wireframing event one of the highlights of the day. And definitely, something we will repeat again when we get the chance. Thanks to everyone who attended, contributed, and helped organize.

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• "Hello World" in C++ AMP

  - by Daniel Moth

  Some say that the equivalent of "hello world" code in the data parallel world is matrix multiplication :) Below is the before C++ AMP and after C++ AMP code. For more on what it all means, watch the recording of my C++ AMP introduction (the example below is part of the session). void MatrixMultiply(vector<float>& vC, const vector<float>& vA, const vector<float>& vB, int M, int N, int W ) { for (int y = 0; y < M; y++) { for (int x = 0; x < N; x++) { float sum = 0; for(int i = 0; i < W; i++) { sum += vA[y * W + i] * vB[i * N + x]; } vC[y * N + x] = sum; } } } Change the function to use C++ AMP and hence offload the computation to the GPU, and now the calling code (which I am not showing) needs no changes and the overall operation gives you really nice speed up for large datasets…  #include <amp.h> using namespace concurrency; void MatrixMultiply(vector<float>& vC, const vector<float>& vA, const vector<float>& vB, int M, int N, int W ) { array_view<const float,2> a(M, W, vA); array_view<const float,2> b(W, N, vB); array_view<writeonly<float>,2> c(M, N, vC); parallel_for_each( c.grid, [=](index<2> idx) mutable restrict(direct3d) { float sum = 0; for(int i = 0; i < a.x; i++) { sum += a(idx.y, i) * b(i, idx.x); } c[idx] = sum; } ); } Again, you can understand the elements above, by using my C++ AMP presentation slides and recording… Stay tuned for more… Comments about this post welcome at the original blog.

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• Mutable Records in F#

  - by MarkPearl

  I’m loving my expert F# book – today I thought I would give a post on using mutable records as covered in Chapter 4 of Expert F#. So as they explain the simplest mutable data structures in F# are mutable records. The whole concept of things by default being immutable is a new one for me from my C# background. Anyhow… lets look at some C# code first. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace MutableRecords { public class DiscreteEventCounter { public int Total { get; set; } public int Positive { get; set; } public string Name { get; private set; } public DiscreteEventCounter(string name) { Name = name; } } class Program { private static void recordEvent(DiscreteEventCounter s, bool isPositive) { s.Total += 1; if (isPositive) s.Positive += 1; } private static void reportStatus (DiscreteEventCounter s) { Console.WriteLine("We have {0} {1} out of {2}", s.Positive, s.Name, s.Total); } static void Main(string[] args) { var longCounter = new DiscreteEventCounter("My Discrete Counter"); recordEvent(longCounter, true); recordEvent(longCounter, true); reportStatus(longCounter); Console.ReadLine(); } } } Quite simple, we have a class that has a few values. We instantiate an instance of the class and perform increments etc on the instance. Now lets look at an equivalent F# sample. namespace EncapsulationNS module Module1 = open System type DiscreteEventCounter = { mutable Total : int mutable Positive : int Name : string } let recordEvent (s: DiscreteEventCounter) isPositive = s.Total <- s.Total+1 if isPositive then s.Positive <- s.Positive+1 let reportStatus (s: DiscreteEventCounter) = printfn "We have %d %s out of %d" s.Positive s.Name s.Total let newCounter nm = { Total = 0; Positive = 0; Name = nm } // // Using it... // let longCounter = newCounter "My Discrete Counter" recordEvent longCounter (true) recordEvent longCounter (true) reportStatus longCounter System.Console.ReadLine() Notice in the type declaration of the DiscreteEventCounter we had to explicitly declare that the total and positive value holders were mutable. And that’s it – a very simple example of mutable types.

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• Use Expressions with LINQ to Entities

  - by EltonStoneman

  [Source: http://geekswithblogs.net/EltonStoneman] Recently I've been putting together a generic approach for paging the response from a WCF service. Paging changes the service signature, so it's not as simple as adding a behavior to an existing service in config, but the complexity of the paging is isolated in a generic base class. We're using the Entity Framework talking to SQL Server, so when we ask for a page using LINQ's .Take() method we get a nice efficient SQL query for just the rows we want, with minimal impact on SQL Server and network traffic. We use the maximum ID of the record returned as a high-water mark (rather than using .Skip() to go to the next record), so the approach caters for records being deleted between page requests. In the paged response we include a HasMorePages indicator, computed by comparing the max ID in the page of results to the max ID for the whole resultset - if the latter is bigger, then there are more pages. In some quick performance testing, the paged version of the service performed much more slowly than the unpaged version, which was unexpected. We narrowed it down to the code which gets the max ID for the full resultset - instead of building an efficient MAX() SQL query, EF was returning the whole resultset and then computing the max ID in the service layer. It's easy to reproduce - take this AdventureWorks query:             var context = new AdventureWorksEntities();             var query = from od in context.SalesOrderDetail                         where od.ModifiedDate >= modified                          && od.SalesOrderDetailID.CompareTo(id) > 0                         orderby od.SalesOrderDetailID                         select od;   We can find the maximum SalesOrderDetailID like this:             var maxIdEfficiently = query.Max(od => od.SalesOrderDetailID);   which produces our efficient MAX() SQL query. If we're doing this generically and we already have the ID function in a Func:             Func<SalesOrderDetail, int> idFunc = od => od.SalesOrderDetailID;             var maxIdInefficiently = query.Max(idFunc);   This fetches all the results from the query and then runs the Max() function in code. If you look at the difference in Reflector, the first call passes an Expression to the Max(), while the second call passes a Func. So it's an easy fix - wrap the Func in an Expression:             Expression<Func<SalesOrderDetail, int>> idExpression = od => od.SalesOrderDetailID;             var maxIdEfficientlyAgain = query.Max(idExpression);   - and we're back to running an efficient MAX() statement. Evidently the EF provider can dissect an Expression and build its equivalent in SQL, but it can't do that with Funcs.

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