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• Vim Regex to replace tags

  - by Rudiger Wolf

  I am lookin for a regex express to remove the email addresses from a text file. Input file: Hannah Churchman <[email protected]>; Julie Drew <[email protected]>; Output file: Hannah Churchman; Julie Drew; I thought a generic regex shuch as s/<(.*?)//g would be a good starting point but I am unable to find the right expression for use Vim? something like :%s/ <\(.*?\)>//g does not work. Error is "E486: Pattern not found:". :%s#[^ <]*>##g almost works but it leaves the space and < behind. :%s# <##g to remove the " <" remaining stuff. Any tips on how to better craft this command?

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• Podcast: Advanced MVVM with Josh Smith

  - by craigshoemaker

  Author, Microsoft MVP and accomplished pianist Josh Smith, Sr. UX Developer at IdentityMine, joins the show to discuss some of Model View ViewModel’s more advanced scenarios. Full Speed: download Fast Version: download Josh shares is experience using MVVM gives some real-world advice on: Using modal dialogs Evils and virtues of code behind in views Use of attached behaviors Undo/redo strategies Working with animations Building a task based architecture for managing communication between View and ViewModel Frameworks in the MVVM space The Book Get first-hand experience implementing the solutions to the challenges discussed in the show by reading Josh’s new book ‘Advanced MVVM’. Resources The following resources are mentioned in the show: Laurent Bugnion's mix talk ‘Understanding the Model-View-ViewModel Pattern Josh Smith’s MVVM Foundation Laurent Bugnion’s MVVM Light framework Rob Eisenberg's Caliburn

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• Gone With the Wind?

  - by antony.reynolds

  Where Have All the Composites Gone? I was just asked to help out with an interesting problem at a customer.  All their composites had disappeared from the EM console, none of them showed as loading in the log files and there was an ominous error message in the logs. Symptoms After a server restart the customer noticed that none of his composites were available, they didn’t show in the EM console and in the log files they saw this error message: SEVERE: WLSFabricKernelInitializer.getCompositeList Error during parsing and processing of deployed-composites.xml file This indicates some sort of problem when parsing the deployed-composites.xml file.  This is very bad because the deployed-composites.xml file is basically the table of contents that tells SOA Infrastructure what composites to load and where to find them in MDS.  If you can’t read this file you can’t load any composites and your SOA Server now has all the utility of a chocolate teapot. Verification We can look at the deployed-composites.xml file from MDS either by connecting JDeveloper to MDS, exporting the file using WLST or exporting the whole soa-infra MDS partition by using EM->SOA->soa-infra->Administration->MDS Configuration.  Exporting via EM is probably the easiest because it then prepares you to fix the problem later.  After exporting the partition to local storage on the SOA Server I then ran an XSLT transform across the file deployed-composites/deployed-composites.xml. <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/1999/xhtml">     <xsl:output indent="yes"/>     <xsl:template match="/">         <testResult>             <composite-series>                 <xsl:attribute name="elementCount"><xsl:value-of select="count(deployed-composites/composite-series)"/></xsl:attribute>                 <xsl:attribute name="nameAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series[@name])"/></xsl:attribute>                 <xsl:attribute name="defaultAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series[@default])"/></xsl:attribute>                 <composite-revision>                     <xsl:attribute name="elementCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision)"/></xsl:attribute>                     <xsl:attribute name="dnAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@dn])"/></xsl:attribute>                     <xsl:attribute name="stateAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@state])"/></xsl:attribute>                     <xsl:attribute name="modeAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@mode])"/></xsl:attribute>                     <xsl:attribute name="locationAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@location])"/></xsl:attribute>                     <composite>                         <xsl:attribute name="elementCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision/composite)"/></xsl:attribute>                         <xsl:attribute name="dnAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision/composite[@dn])"/></xsl:attribute>                         <xsl:attribute name="deployedTimeAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision/composite[@deployedTime])"/></xsl:attribute>                     </composite>                 </composite-revision>                 <xsl:apply-templates select="deployed-composites/composite-series"/>             </composite-series>         </testResult>     </xsl:template>     <xsl:template match="composite-series">             <xsl:if test="not(@name) or not(@default) or composite-revision[not(@dn) or not(@state) or not(@mode) or not(@location)]">                 <ErrorNode>                     <xsl:attribute name="elementPos"><xsl:value-of select="position()"/></xsl:attribute>                     <xsl:copy-of select="."/>                 </ErrorNode>             </xsl:if>     </xsl:template> </xsl:stylesheet> The output from this is not pretty but it shows any <composite-series> tags that are missing expected attributes (name and default).  It also shows how many composites are in the file (111) and how many revisions of those composites (115). <?xml version="1.0" encoding="UTF-8"?> <testResult xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/1999/xhtml">    <composite-series elementCount="111" nameAttributeCount="110" defaultAttributeCount="110">       <composite-revision elementCount="115" dnAttributeCount="114" stateAttributeCount="115"                           modeAttributeCount="115"                           locationAttributeCount="114">          <composite elementCount="115" dnAttributeCount="114" deployedTimeAttributeCount="115"/>       </composite-revision>       <ErrorNode elementPos="82">          <composite-series xmlns="">             <composite-revision state="on" mode="active">                <composite deployedTime="2010-12-15T11:50:16.067+01:00"/>             </composite-revision>          </composite-series>       </ErrorNode>    </composite-series> </testResult> From this I could see that one of the <composite-series> elements (number 82 of 111) seemed to be corrupt. Having found the problem I now needed to fix it. Fixing the Problem The solution was really quite easy.  First for safeties sake I took a backup of the exported MDS partition.  I then edited the deployed-composites/deployed-composites.xml file to remove the offending <composite-series> tag. Finally I restarted the SOA domain and was rewarded by seeing that the deployed composites were now visible. Summary One possible cause of not being able to see deployed composites after a SOA 11g system restart is a corrupt deployed-composites.xml file.  Retrieving this file from MDS, repairing it, and replacing it back into MDS can solve the problem.  This still leaves the problem of how did this file become corrupt!

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• Silverlight 5 Hosting :: Features in Silverlight 5 and Release Date

  - by mbridge

  Silverlight 5 is finally announced in the Silverlight FireStarter Event on the 2nd December, 2010. This new version of Silverlight which was earlier labeled as 'Future of Microsoft Silverlight' has now come much closer to go live as the first Silverlight 5 Beta version is expected to be shipped during the early months of 2011. However for the full fledged and the final release of Silverlight 5, we have to wait many more months as the same is likely to be made available within the Q3 2011. As would have been usually expected, this latest edition would feature many new capabilities thereby extending the developer productivity to a whole new dimension of premium media experience and feature-rich business applications. It comes along with many new feature updates as well as the inclusion of new technologies to improve the standard of the Silverlight applications which are now fine-tuned to produce next generation business and media solutions that is capable to meet the requirements of the advanced web-based app development. The Silverlight 5 is all set to replace the previous fourth version which now includes more than forty new features while also dropping various deprecated elements that was prevalent earlier. It has brought around some major performance enhancements and also included better support for various other tools and technologies. Following are some of the changes that are registered to be available under the Silverlight 5 Beta edition which is scheduled to be launched during the Q1 2011. Silverlight 5 : Premium Media Experiences The media features of Silverlight 5 has seen some major enhancements with a lot of optimizations being made to deliver richer solutions. It's capability has now been extended to make things easier, faster and capable of performing the desired tasks in the most efficient manner. The Silverlight media solutions has already been a part of many companies in the recent days where various on-demand Silverlight services were featured but with the arrival of the next generation premium media solution of Silverlight 5, it is expected to register new heights of success and global user acclamation for using it with many esteemed web-based projects and media solutions. - The most happening element in the new Silverlight 5 will be its support for utilizing the GPU based hardware acceleration which is intended to lower down the CPU load to a significant extent and thereby allowing faster rendering of media contents without consuming much resources. This feature is believed to be particularly helpful for low configured machines to run full HD media content without any lagging caused due to processor load. It will hence be one great feature to revolutionize the new generation high quality media contents to be available within the web in a more efficient manner with its hardware decoded video playback capabilities. - With the inclusion of hardware video decoding to minimize the processor load, the Silverlight 5 also comes with another optimization enhancement to also reduce the power consumption level by making new methods to deal with the power-saver settings. With this optimization in effect, the computer would be automatically allowed to switch to sleep mode while no video playback is in progress and also to prevent any screensavers to popup and cause annoyances during any video playback. There would also be other power saver options which will be made available to best suit the users requirements and purpose. - The Silverlight trickplay feature is another great way to tweak any silverlight powered media content as is used for many video tutorial sites or for dealing with any sort of presentations. This feature enables the user to modify the playback speed to either slowdown or speedup during the playback durations based on the requirements without compromising on the quality of output. Normally such manipulations always makes the content's audio to go off-pitch, but the same will not be the case with TrickPlay and the audio would seamlessly progress with the video without skipping any of its part. - In addition to all of the above, the new Silverlight 5 will be featuring wireless control of all the media contents by making use of remote controllers. With the use of such remote devices, it will be easier to handle the various media playback controls thereby providing more freedom while experiencing the premium media services. Silverlight 5 : Business Application Development The application development standard has been extended with more possibilities by bringing forth new and useful technologies and also reviving the existing methods to work better than what it was used to. From the UI improvements to advanced technical aspects, the Silverlight 5 scores high on all grounds to produce great next generation business delivered applications by putting in more creativity and resourceful touch to all the apps being produced with it. - The WPF feature of Silverlight is made more effective by introducing new standards of Databinding which is intended to improve the productivity standards of the Silverlight application developer. It brings in a lot of convenience in debugging the databinding components or expressions and hence making things work in a flawless manner. Some additional features related to databinding includes that of Ancestor RelativeSource, Implicit DataTemplates and Model View ViewModel (MVVM) support with DataContextChanged event and many other new features relating it. - It now comes with a refined text and printing service which facilitates better clarity of the text rendering and also many positive changes which are being applied to the layout pattern. New supports has been added to include OpenType font, multi-column text, linked-text containers and character leading support to name a few among the available features.This also includes some important printing aspects like that of Postscript Vector Printing API which allows to program our printing tasks in a user defined way and Pivot functionality for visualization concerns of informations. - The Graphics support is the key improvements being incorporated which now enables to utilize three dimensional graphics pattern using GPU acceleration. It can manage to provide some really cool visualizations being curved to provide media contents within the business apps with also the support for full HD contents at 1080p quality. - Silverlight 5 includes the support for 64-bit operating systems and relevant browsers and is also optimized to provide better performance. It can support the background thread for the networking which can reduce the latency of the network to a considerable extent. The Out-of-Browser functionality adds the support for utilizing various libraries and also the Win32 API. It also comes with testing support with VS 2010 which is mostly an automated procedure and has also enabled increased security aspects of all the Silverlight 5 developed applications by using the improved version of group policy support.

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• Adventures in MVVM &ndash; My ViewModel Base

  - by Brian Genisio's House Of Bilz

  More Adventures in MVVM First, I’d like to say: THIS IS NOT A NEW MVVM FRAMEWORK. I tend to believe that MVVM support code should be specific to the system you are building and the developers working on it.  I have yet to find an MVVM framework that does everything I want it to without doing too much.  Don’t get me wrong… there are some good frameworks out there.  I just like to pick and choose things that make sense for me.  I’d also like to add that some of these features only work in WPF.  As of Silveright 4, they don’t support binding to dynamic properties, so some of the capabilities are lost. That being said, I want to share my ViewModel base class with the world.  I have had several conversations with people about the problems I have solved using this ViewModel base.  A while back, I posted an article about some experiments with a “Rails Inspired ViewModel”.  What followed from those ideas was a ViewModel base class that I take with me and use in my projects.  It has a lot of features, all designed to reduce the friction in writing view models. I have put the code out on Codeplex under the project: ViewModelSupport. Finally, this article focuses on the ViewModel and only glosses over the View and the Model.  Without all three, you don’t have MVVM.  But this base class is for the ViewModel, so that is what I am focusing on. Features: Automatic Command Plumbing Property Change Notification Strongly Typed Property Getter/Setters Dynamic Properties Default Property values Derived Properties Automatic Method Execution Command CanExecute Change Notification Design-Time Detection What about Silverlight? Automatic Command Plumbing This feature takes the plumbing out of creating commands.  The common pattern for commands in a ViewModel is to have an Execute method as well as an optional CanExecute method.  To plumb that together, you create an ICommand Property, and set it in the constructor like so: Before public class AutomaticCommandViewModel { public AutomaticCommandViewModel() { MyCommand = new DelegateCommand(Execute_MyCommand, CanExecute_MyCommand); } public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } public DelegateCommand MyCommand { get; private set; } } With the base class, this plumbing is automatic and the property (MyCommand of type ICommand) is created for you.  The base class uses the convention that methods be prefixed with Execute_ and CanExecute_ in order to be plumbed into commands with the property name after the prefix.  You are left to be expressive with your behavior without the plumbing.  If you are wondering how CanExecuteChanged is raised, see the later section “Command CanExecute Change Notification”. After public class AutomaticCommandViewModel : ViewModelBase { public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } }   Property Change Notification One thing that always kills me when implementing ViewModels is how to make properties that notify when they change (via the INotifyPropertyChanged interface).  There have been many attempts to make this more automatic.  My base class includes one option.  There are others, but I feel like this works best for me. The common pattern (without my base class) is to create a private backing store for the variable and specify a getter that returns the private field.  The setter will set the private field and fire an event that notifies the change, only if the value has changed. Before public class PropertyHelpersViewModel : INotifyPropertyChanged { private string text; public string Text { get { return text; } set { if(text != value) { text = value; RaisePropertyChanged("Text"); } } } protected void RaisePropertyChanged(string propertyName) { var handlers = PropertyChanged; if(handlers != null) handlers(this, new PropertyChangedEventArgs(propertyName)); } public event PropertyChangedEventHandler PropertyChanged; } This way of defining properties is error-prone and tedious.  Too much plumbing.  My base class eliminates much of that plumbing with the same functionality: After public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get<string>("Text"); } set { Set("Text", value);} } }   Strongly Typed Property Getters/Setters It turns out that we can do better than that.  We are using a strongly typed language where the use of “Magic Strings” is often frowned upon.  Lets make the names in the getters and setters strongly typed: A refinement public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get(() => Text); } set { Set(() => Text, value); } } }   Dynamic Properties In C# 4.0, we have the ability to program statically OR dynamically.  This base class lets us leverage the powerful dynamic capabilities in our ecosystem. (This is how the automatic commands are implemented, BTW)  By calling Set(“Foo”, 1), you have now created a dynamic property called Foo.  It can be bound against like any static property.  The opportunities are endless.  One great way to exploit this behavior is if you have a customizable view engine with templates that bind to properties defined by the user.  The base class just needs to create the dynamic properties at runtime from information in the model, and the custom template can bind even though the static properties do not exist. All dynamic properties still benefit from the notifiable capabilities that static properties do. For any nay-sayers out there that don’t like using the dynamic features of C#, just remember this: the act of binding the View to a ViewModel is dynamic already.  Why not exploit it?  Get over it :) Just declare the property dynamically public class DynamicPropertyViewModel : ViewModelBase { public DynamicPropertyViewModel() { Set("Foo", "Bar"); } } Then reference it normally <TextBlock Text="{Binding Foo}" />   Default Property Values The Get() method also allows for default properties to be set.  Don’t set them in the constructor.  Set them in the property and keep the related code together: public string Text { get { return Get(() => Text, "This is the default value"); } set { Set(() => Text, value);} }   Derived Properties This is something I blogged about a while back in more detail.  This feature came from the chaining of property notifications when one property affects the results of another, like this: Before public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); RaisePropertyChanged("Percentage"); RaisePropertyChanged("Output"); } } public int Percentage { get { return (int)(100 * Score); } } public string Output { get { return "You scored " + Percentage + "%."; } } } The problem is: The setter for Score has to be responsible for notifying the world that Percentage and Output have also changed.  This, to me, is backwards.    It certainly violates the “Single Responsibility Principle.” I have been bitten in the rear more than once by problems created from code like this.  What we really want to do is invert the dependency.  Let the Percentage property declare that it changes when the Score Property changes. After public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public int Percentage { get { return (int)(100 * Score); } } [DependsUpon("Percentage")] public string Output { get { return "You scored " + Percentage + "%."; } } }   Automatic Method Execution This one is extremely similar to the previous, but it deals with method execution as opposed to property.  When you want to execute a method triggered by property changes, let the method declare the dependency instead of the other way around. Before public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); WhenScoreChanges(); } } public void WhenScoreChanges() { // Handle this case } } After public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public void WhenScoreChanges() { // Handle this case } }   Command CanExecute Change Notification Back to Commands.  One of the responsibilities of commands that implement ICommand – it must fire an event declaring that CanExecute() needs to be re-evaluated.  I wanted to wait until we got past a few concepts before explaining this behavior.  You can use the same mechanism here to fire off the change.  In the CanExecute_ method, declare the property that it depends upon.  When that property changes, the command will fire a CanExecuteChanged event, telling the View to re-evaluate the state of the command.  The View will make appropriate adjustments, like disabling the button. DependsUpon works on CanExecute methods as well public class CanExecuteViewModel : ViewModelBase { public void Execute_MakeLower() { Output = Input.ToLower(); } [DependsUpon("Input")] public bool CanExecute_MakeLower() { return !string.IsNullOrWhiteSpace(Input); } public string Input { get { return Get(() => Input); } set { Set(() => Input, value);} } public string Output { get { return Get(() => Output); } set { Set(() => Output, value); } } }   Design-Time Detection If you want to add design-time data to your ViewModel, the base class has a property that lets you ask if you are in the designer.  You can then set some default values that let your designer see what things might look like in runtime. Use the IsInDesignMode property public DependantPropertiesViewModel() { if(IsInDesignMode) { Score = .5; } }   What About Silverlight? Some of the features in this base class only work in WPF.  As of version 4, Silverlight does not support binding to dynamic properties.  This, in my opinion, is a HUGE limitation.  Not only does it keep you from using many of the features in this ViewModel, it also keeps you from binding to ViewModels designed in IronRuby.  Does this mean that the base class will not work in Silverlight?  No.  Many of the features outlined in this article WILL work.  All of the property abstractions are functional, as long as you refer to them statically in the View.  This, of course, means that the automatic command hook-up doesn’t work in Silverlight.  You need to plumb it to a static property in order for the Silverlight View to bind to it.  Can I has a dynamic property in SL5?     Good to go? So, that concludes the feature explanation of my ViewModel base class.  Feel free to take it, fork it, whatever.  It is hosted on CodePlex.  When I find other useful additions, I will add them to the public repository.  I use this base class every day.  It is mature, and well tested.  If, however, you find any problems with it, please let me know!  Also, feel free to suggest patches to me via the CodePlex site.  :)

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• Console keyboard input OOP

  - by Alexandre P. Levasseur

  I am trying to build a very simple console-based game with a focus on using OOP instead of procedural programming because I intend to build up on that code for more complex projects. I am wondering if there is a design pattern that nicely handles this use case: There is a Player class with a MakeMove() method interacting with the board game. The MakeMove() method has to somehow get the user input yet I do not want to code it into the Player class as this would reduce cohesion and augment coupling. I was thinking of maybe having some controller class handle the sequence of events and thus the calls to keyboard input. However, that controller class would need to be able to handle differently the subclasses of Player (e.g. the AI class does not require keyboard input). Thoughts ?

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• The Presentation Secrets of Steve Jobs

  - by guybarrette

  A few years go, I got interested in presentation styles after reading Cliff Atkinson’s Beyond Bullet Points book.  At that time, it was obvious that the Microsoft presentation culture was kind of missing the point by having far too many bullet points. I recently picked up Carmine Gallo’s The Presentation Secrets of Steve Jobs.  I enjoyed this short read (238 pages) book full of presentation tips.  The best advise that I got from reading this book is that you must have an antagonist in your presentation.  This will help the audience visualize and understand the problem (antagonist) and the solution (what you present).  When presenting a technical topic, it is easy to forget to explain what problem is being solved by using this new technology/technique/pattern/API. This is a great read for anyone giving presentations, technical or not.     var addthis_pub="guybarrette";

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• SQL SERVER – Concurrency Basics – Guest Post by Vinod Kumar

  - by pinaldave

  This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions from SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. Learning is always fun when it comes to SQL Server and learning the basics again can be more fun. I did write about Transaction Logs and recovery over my blogs and the concept of simplifying the basics is a challenge. In the real world we always see checks and queues for a process – say railway reservation, banks, customer supports etc there is a process of line and queue to facilitate everyone. Shorter the queue higher is the efficiency of system (a.k.a higher is the concurrency). Every database does implement this using checks like locking, blocking mechanisms and they implement the standards in a way to facilitate higher concurrency. In this post, let us talk about the topic of Concurrency and what are the various aspects that one needs to know about concurrency inside SQL Server. Let us learn the concepts as one-liners: Concurrency can be defined as the ability of multiple processes to access or change shared data at the same time. The greater the number of concurrent user processes that can be active without interfering with each other, the greater the concurrency of the database system. Concurrency is reduced when a process that is changing data prevents other processes from reading that data or when a process that is reading data prevents other processes from changing that data. Concurrency is also affected when multiple processes are attempting to change the same data simultaneously. Two approaches to managing concurrent data access: Optimistic Concurrency Model Pessimistic Concurrency Model Concurrency Models Pessimistic Concurrency Default behavior: acquire locks to block access to data that another process is using. Assumes that enough data modification operations are in the system that any given read operation is likely affected by a data modification made by another user (assumes conflicts will occur). Avoids conflicts by acquiring a lock on data being read so no other processes can modify that data. Also acquires locks on data being modified so no other processes can access the data for either reading or modifying. Readers block writer, writers block readers and writers. Optimistic Concurrency Assumes that there are sufficiently few conflicting data modification operations in the system that any single transaction is unlikely to modify data that another transaction is modifying. Default behavior of optimistic concurrency is to use row versioning to allow data readers to see the state of the data before the modification occurs. Older versions of the data are saved so a process reading data can see the data as it was when the process started reading and not affected by any changes being made to that data. Processes modifying the data is unaffected by processes reading the data because the reader is accessing a saved version of the data rows. Readers do not block writers and writers do not block readers, but, writers can and will block writers. Transaction Processing A transaction is the basic unit of work in SQL Server. Transaction consists of SQL commands that read and update the database but the update is not considered final until a COMMIT command is issued (at least for an explicit transaction: marked with a BEGIN TRAN and the end is marked by a COMMIT TRAN or ROLLBACK TRAN). Transactions must exhibit all the ACID properties of a transaction. ACID Properties Transaction processing must guarantee the consistency and recoverability of SQL Server databases. Ensures all transactions are performed as a single unit of work regardless of hardware or system failure. A – Atomicity C – Consistency I – Isolation D- Durability Atomicity: Each transaction is treated as all or nothing – it either commits or aborts. Consistency: ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct.  Consistency is honored even in the event of a system failure. Isolation: separates concurrent transactions from the updates of other incomplete transactions. SQL Server accomplishes isolation among transactions by locking data or creating row versions. Durability: After a transaction commits, the durability property ensures that the effects of the transaction persist even if a system failure occurs. If a system failure occurs while a transaction is in progress, the transaction is completely undone, leaving no partial effects on data. Transaction Dependencies In addition to supporting all four ACID properties, a transaction might exhibit few other behaviors (known as dependency problems or consistency problems). Lost Updates: Occur when two processes read the same data and both manipulate the data, changing its value and then both try to update the original data to the new value. The second process might overwrite the first update completely. Dirty Reads: Occurs when a process reads uncommitted data. If one process has changed data but not yet committed the change, another process reading the data will read it in an inconsistent state. Non-repeatable Reads: A read is non-repeatable if a process might get different values when reading the same data in two reads within the same transaction. This can happen when another process changes the data in between the reads that the first process is doing. Phantoms: Occurs when membership in a set changes. It occurs if two SELECT operations using the same predicate in the same transaction return a different number of rows. Isolation Levels SQL Server supports 5 isolation levels that control the behavior of read operations. Read Uncommitted All behaviors except for lost updates are possible. Implemented by allowing the read operations to not take any locks, and because of this, it won’t be blocked by conflicting locks acquired by other processes. The process can read data that another process has modified but not yet committed. When using the read uncommitted isolation level and scanning an entire table, SQL Server can decide to do an allocation order scan (in page-number order) instead of a logical order scan (following page pointers). If another process doing concurrent operations changes data and move rows to a new location in the table, the allocation order scan can end up reading the same row twice. Also can happen if you have read a row before it is updated and then an update moves the row to a higher page number than your scan encounters later. Performing an allocation order scan under Read Uncommitted can cause you to miss a row completely – can happen when a row on a high page number that hasn’t been read yet is updated and moved to a lower page number that has already been read. Read Committed Two varieties of read committed isolation: optimistic and pessimistic (default). Ensures that a read never reads data that another application hasn’t committed. If another transaction is updating data and has exclusive locks on data, your transaction will have to wait for the locks to be released. Your transaction must put share locks on data that are visited, which means that data might be unavailable for others to use. A share lock doesn’t prevent others from reading but prevents them from updating. Read committed (snapshot) ensures that an operation never reads uncommitted data, but not by forcing other processes to wait. SQL Server generates a version of the changed row with its previous committed values. Data being changed is still locked but other processes can see the previous versions of the data as it was before the update operation began. Repeatable Read This is a Pessimistic isolation level. Ensures that if a transaction revisits data or a query is reissued the data doesn’t change. That is, issuing the same query twice within a transaction cannot pickup any changes to data values made by another user’s transaction because no changes can be made by other transactions. However, this does allow phantom rows to appear. Preventing non-repeatable read is a desirable safeguard but cost is that all shared locks in a transaction must be held until the completion of the transaction. Snapshot Snapshot Isolation (SI) is an optimistic isolation level. Allows for processes to read older versions of committed data if the current version is locked. Difference between snapshot and read committed has to do with how old the older versions have to be. It’s possible to have two transactions executing simultaneously that give us a result that is not possible in any serial execution. Serializable This is the strongest of the pessimistic isolation level. Adds to repeatable read isolation level by ensuring that if a query is reissued rows were not added in the interim, i.e, phantoms do not appear. Preventing phantoms is another desirable safeguard, but cost of this extra safeguard is similar to that of repeatable read – all shared locks in a transaction must be held until the transaction completes. In addition serializable isolation level requires that you lock data that has been read but also data that doesn’t exist. Ex: if a SELECT returned no rows, you want it to return no. rows when the query is reissued. This is implemented in SQL Server by a special kind of lock called the key-range lock. Key-range locks require that there be an index on the column that defines the range of values. If there is no index on the column, serializable isolation requires a table lock. Gets its name from the fact that running multiple serializable transactions at the same time is equivalent of running them one at a time. Now that we understand the basics of what concurrency is, the subsequent blog posts will try to bring out the basics around locking, blocking, deadlocks because they are the fundamental blocks that make concurrency possible. Now if you are with me – let us continue learning for SQL Server Locking Basics. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Concurrency

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• Announcing ASP.NET MVC 3 (Release Candidate 2)

  - by ScottGu

  Earlier today the ASP.NET team shipped the final release candidate (RC2) for ASP.NET MVC 3.  You can download and install it here. Almost there… Today’s RC2 release is the near-final release of ASP.NET MVC 3, and is a true “release candidate” in that we are hoping to not make any more code changes with it.  We are publishing it today so that people can do final testing with it, let us know if they find any last minute “showstoppers”, and start updating their apps to use it.  We will officially ship the final ASP.NET MVC 3 “RTM” build in January. Works with both VS 2010 and VS 2010 SP1 Beta Today’s ASP.NET MVC 3 RC2 release works with both the shipping version of Visual Studio 2010 / Visual Web Developer 2010 Express, as well as the newly released VS 2010 SP1 Beta.  This means that you do not need to install VS 2010 SP1 (or the SP1 beta) in order to use ASP.NET MVC 3.  It works just fine with the shipping Visual Studio 2010.  I’ll do a blog post next week, though, about some of the nice additional feature goodies that come with VS 2010 SP1 (including IIS Express and SQL CE support within VS) which make the dev experience for both ASP.NET Web Forms and ASP.NET MVC even better. Bugs and Perf Fixes Today’s ASP.NET MVC 3 RC2 build contains many bug fixes and performance optimizations.  Our latest performance tests indicate that ASP.NET MVC 3 is now faster than ASP.NET MVC 2, and that existing ASP.NET MVC applications will experience a slight performance increase when updated to run using ASP.NET MVC 3. Final Tweaks and Fit-N-Finish In addition to bug fixes and performance optimizations, today’s RC2 build contains a number of last-minute feature tweaks and “fit-n-finish” changes for the new ASP.NET MVC 3 features.  The feedback and suggestions we’ve received during the public previews has been invaluable in guiding these final tweaks, and we really appreciate people’s support in sending this feedback our way.  Below is a short-list of some of the feature changes/tweaks made between last month’s ASP.NET MVC 3 RC release and today’s ASP.NET MVC 3 RC2 release: jQuery updates and addition of jQuery UI The default ASP.NET MVC 3 project templates have been updated to include jQuery 1.4.4 and jQuery Validation 1.7.  We are also excited to announce today that we are including jQuery UI within our default ASP.NET project templates going forward.  jQuery UI provides a powerful set of additional UI widgets and capabilities.  It will be added by default to your project’s \scripts folder when you create new ASP.NET MVC 3 projects. Improved View Scaffolding The T4 templates used for scaffolding views with the Add-View dialog now generates views that use Html.EditorFor instead of helpers such as Html.TextBoxFor. This change enables you to optionally annotate models with metadata (using data annotation attributes) to better customize the output of your UI at runtime. The Add View scaffolding also supports improved detection and usage of primary key information on models (including support for naming conventions like ID, ProductID, etc).  For example: the Add View dialog box uses this information to ensure that the primary key value is not scaffold as an editable form field, and that links between views are auto-generated correctly with primary key information. The default Edit and Create templates also now include references to the jQuery scripts needed for client validation.  Scaffold form views now support client-side validation by default (no extra steps required).  Client-side validation with ASP.NET MVC 3 is also done using an unobtrusive javascript approach – making pages fast and clean. [ControllerSessionState] –> [SessionState] ASP.NET MVC 3 adds support for session-less controllers.  With the initial RC you used a [ControllerSessionState] attribute to specify this.  We shortened this in RC2 to just be [SessionState]: Note that in addition to turning off session state, you can also set it to be read-only (which is useful for webfarm scenarios where you are reading but not updating session state on a particular request). [SkipRequestValidation] –> [AllowHtml] ASP.NET MVC includes built-in support to protect against HTML and Cross-Site Script Injection Attacks, and will throw an error by default if someone tries to post HTML content as input.  Developers need to explicitly indicate that this is allowed (and that they’ve hopefully built their app to securely support it) in order to enable it. With ASP.NET MVC 3, we are also now supporting a new attribute that you can apply to properties of models/viewmodels to indicate that HTML input is enabled, which enables much more granular protection in a DRY way.  In last month’s RC release this attribute was named [SkipRequestValidation].  With RC2 we renamed it to [AllowHtml] to make it more intuitive: Setting the above [AllowHtml] attribute on a model/viewmodel will cause ASP.NET MVC 3 to turn off HTML injection protection when model binding just that property. Html.Raw() helper method The new Razor view engine introduced with ASP.NET MVC 3 automatically HTML encodes output by default.  This helps provide an additional level of protection against HTML and Script injection attacks. With RC2 we are adding a Html.Raw() helper method that you can use to explicitly indicate that you do not want to HTML encode your output, and instead want to render the content “as-is”: ViewModel/View –> ViewBag ASP.NET MVC has (since V1) supported a ViewData[] dictionary within Controllers and Views that enables developers to pass information from a Controller to a View in a late-bound way.  This approach can be used instead of, or in combination with, a strongly-typed model class.  The below code demonstrates a common use case – where a strongly typed Product model is passed to the view in addition to two late-bound variables via the ViewData[] dictionary: With ASP.NET MVC 3 we are introducing a new API that takes advantage of the dynamic type support within .NET 4 to set/retrieve these values.  It allows you to use standard “dot” notation to specify any number of additional variables to be passed, and does not require that you create a strongly-typed class to do so.  With earlier previews of ASP.NET MVC 3 we exposed this API using a dynamic property called “ViewModel” on the Controller base class, and with a dynamic property called “View” within view templates.  A lot of people found the fact that there were two different names confusing, and several also said that using the name ViewModel was confusing in this context – since often you create strongly-typed ViewModel classes in ASP.NET MVC, and they do not use this API.  With RC2 we are exposing a dynamic property that has the same name – ViewBag – within both Controllers and Views.  It is a dynamic collection that allows you to pass additional bits of data from your controller to your view template to help generate a response.  Below is an example of how we could use it to pass a time-stamp message as well as a list of all categories to our view template: Below is an example of how our view template (which is strongly-typed to expect a Product class as its model) can use the two extra bits of information we passed in our ViewBag to generate the response.  In particular, notice how we are using the list of categories passed in the dynamic ViewBag collection to generate a dropdownlist of friendly category names to help set the CategoryID property of our Product object.  The above Controller/View combination will then generate an HTML response like below.    Output Caching Improvements ASP.NET MVC 3’s output caching system no longer requires you to specify a VaryByParam property when declaring an [OutputCache] attribute on a Controller action method.  MVC3 now automatically varies the output cached entries when you have explicit parameters on your action method – allowing you to cleanly enable output caching on actions using code like below: In addition to supporting full page output caching, ASP.NET MVC 3 also supports partial-page caching – which allows you to cache a region of output and re-use it across multiple requests or controllers.  The [OutputCache] behavior for partial-page caching was updated with RC2 so that sub-content cached entries are varied based on input parameters as opposed to the URL structure of the top-level request – which makes caching scenarios both easier and more powerful than the behavior in the previous RC. @model declaration does not add whitespace In earlier previews, the strongly-typed @model declaration at the top of a Razor view added a blank line to the rendered HTML output. This has been fixed so that the declaration does not introduce whitespace. Changed "Html.ValidationMessage" Method to Display the First Useful Error Message The behavior of the Html.ValidationMessage() helper was updated to show the first useful error message instead of simply displaying the first error. During model binding, the ModelState dictionary can be populated from multiple sources with error messages about the property, including from the model itself (if it implements IValidatableObject), from validation attributes applied to the property, and from exceptions thrown while the property is being accessed. When the Html.ValidationMessage() method displays a validation message, it now skips model-state entries that include an exception, because these are generally not intended for the end user. Instead, the method looks for the first validation message that is not associated with an exception and displays that message. If no such message is found, it defaults to a generic error message that is associated with the first exception. RemoteAttribute “Fields” -> “AdditionalFields” ASP.NET MVC 3 includes built-in remote validation support with its validation infrastructure.  This means that the client-side validation script library used by ASP.NET MVC 3 can automatically call back to controllers you expose on the server to determine whether an input element is indeed valid as the user is editing the form (allowing you to provide real-time validation updates). You can accomplish this by decorating a model/viewmodel property with a [Remote] attribute that specifies the controller/action that should be invoked to remotely validate it.  With the RC this attribute had a “Fields” property that could be used to specify additional input elements that should be sent from the client to the server to help with the validation logic.  To improve the clarity of what this property does we have renamed it to “AdditionalFields” with today’s RC2 release. ViewResult.Model and ViewResult.ViewBag Properties The ViewResult class now exposes both a “Model” and “ViewBag” property off of it.  This makes it easier to unit test Controllers that return views, and avoids you having to access the Model via the ViewResult.ViewData.Model property. Installation Notes You can download and install the ASP.NET MVC 3 RC2 build here.  It can be installed on top of the previous ASP.NET MVC 3 RC release (it should just replace the bits as part of its setup). The one component that will not be updated by the above setup (if you already have it installed) is the NuGet Package Manager.  If you already have NuGet installed, please go to the Visual Studio Extensions Manager (via the Tools –> Extensions menu option) and click on the “Updates” tab.  You should see NuGet listed there – please click the “Update” button next to it to have VS update the extension to today’s release. If you do not have NuGet installed (and did not install the ASP.NET MVC RC build), then NuGet will be installed as part of your ASP.NET MVC 3 setup, and you do not need to take any additional steps to make it work. Summary We are really close to the final ASP.NET MVC 3 release, and will deliver the final “RTM” build of it next month.  It has been only a little over 7 months since ASP.NET MVC 2 shipped, and I’m pretty amazed by the huge number of new features, improvements, and refinements that the team has been able to add with this release (Razor, Unobtrusive JavaScript, NuGet, Dependency Injection, Output Caching, and a lot, lot more).  I’ll be doing a number of blog posts over the next few weeks talking about many of them in more depth. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• JIT compiler for C, C++, and the likes

  - by Ebrahim

  Is there any just-in-time compiler out there for compiled languages, such as C and C++? (The first names that come to mind are Clang and LLVM! But I don't think they currently support it.) Explanation: I think the software could benefit from runtime profiling feedback and aggressively optimized recompilation of hotspots at runtime, even for compiled-to-machine languages like C and C++. Profile-guided optimization does a similar job, but with the difference a JIT would be more flexible in different environments. In PGO you run your binary prior to releasing it. After you released it, it would use no environment/input feedbacks collected at runtime. So if the input pattern is changed, it is probe to performance penalty. But JIT works well even in that conditions. However I think it is controversial wether the JIT compiling performance benefit outweights its own overhead. Edit: Grammar

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• SQL SERVER – Example of Performance Tuning for Advanced Users with DB Optimizer

  - by Pinal Dave

  Performance tuning is such a subject that everyone wants to master it. In beginning everybody is at a novice level and spend lots of time learning how to master the art of performance tuning. However, as we progress further the tuning of the system keeps on getting very difficult. I have understood in my early career there should be no need of ego in the technology field. There are always better solutions and better ideas out there and we should not resist them. Instead of resisting the change and new wave I personally adopt it. Here is a similar example, as I personally progress to the master level of performance tuning, I face that it is getting harder to come up with optimal solutions. In such scenarios I rely on various tools to teach me how I can do things better. Once I learn about tools, I am often able to come up with better solutions when I face the similar situation next time. A few days ago I had received a query where the user wanted to tune it further to get the maximum out of the performance. I have re-written the similar query with the help of AdventureWorks sample database. SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID; User had similar query to above query was used in very critical report and wanted to get best out of the query. When I looked at the query – here were my initial thoughts Use only column in the select statements as much as you want in the application Let us look at the query pattern and data workload and find out the optimal index for it Before I give further solutions I was told by the user that they need all the columns from all the tables and creating index was not allowed in their system. He can only re-write queries or use hints to further tune this query. Now I was in the constraint box – I believe * was not a great idea but if they wanted all the columns, I believe we can’t do much besides using *. Additionally, if I cannot create a further index, I must come up with some creative way to write this query. I personally do not like to use hints in my application but there are cases when hints work out magically and gives optimal solutions. Finally, I decided to use Embarcadero’s DB Optimizer. It is a fantastic tool and very helpful when it is about performance tuning. I have previously explained how it works over here. First open DBOptimizer and open Tuning Job from File >> New >> Tuning Job. Once you open DBOptimizer Tuning Job follow the various steps indicates in the following diagram. Essentially we will take our original script and will paste that into Step 1: New SQL Text and right after that we will enable Step 2 for Generating Various cases, Step 3 for Detailed Analysis and Step 4 for Executing each generated case. Finally we will click on Analysis in Step 5 which will generate the report detailed analysis in the result pan. The detailed pan looks like. It generates various cases of T-SQL based on the original query. It applies various hints and available hints to the query and generate various execution plans of the query and displays them in the resultant. You can clearly notice that original query had a cost of 0.0841 and logical reads about 607 pages. Whereas various options which are just following it has different execution cost as well logical read. There are few cases where we have higher logical read and there are few cases where as we have very low logical read. If we pay attention the very next row to original query have Merge_Join_Query in description and have lowest execution cost value of 0.044 and have lowest Logical Reads of 29. This row contains the query which is the most optimal re-write of the original query. Let us double click over it. Here is the query: SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID OPTION (MERGE JOIN) If you notice above query have additional hint of Merge Join. With the help of this Merge Join query hint this query is now performing much better than before. The entire process takes less than 60 seconds. Please note that it the join hint Merge Join was optimal for this query but it is not necessary that the same hint will be helpful in all the queries. Additionally, if the workload or data pattern changes the query hint of merge join may be no more optimal join. In that case, we will have to redo the entire exercise once again. This is the reason I do not like to use hints in my queries and I discourage all of my users to use the same. However, if you look at this example, this is a great case where hints are optimizing the performance of the query. It is humanly not possible to test out various query hints and index options with the query to figure out which is the most optimal solution. Sometimes, we need to depend on the efficiency tools like DB Optimizer to guide us the way and select the best option from the suggestion provided. Let me know what you think of this article as well your experience with DB Optimizer. Please leave a comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Lightning talk: Coderetreat

  - by Michael Williamson

  In the spirit of trying to encourage more deliberate practice amongst coders in Red Gate, Lauri Pesonen had the idea of running a coderetreat in Red Gate. Lauri and I ran the first one a few weeks ago: given that neither of us hadn’t even been to a coderetreat before, let alone run one, I think it turned out quite well. The participants gave positive feedback, saying that they enjoyed the day, wrote some thought-provoking code and would do it again. Sam Blackburn was one of the attendees, and gave a lightning talk to the other developers in one of our regular lightning talk sessions: In case you can’t watch the video, I’ve transcribed the talk below, although I’d recommend watching the video if you can — I didn’t have much time to do the transcribing! So, what is a coderetreat? So it’s not just something in Red Gate, there’s a website and everything, although it’s not a very big website. It calls itself a community network. The basic ideas behind coderetreat are: you’ve got one day, and you split it into one hour sections. You spend three quarters of that coding, and do a little retrospective at the end. You’re supposed to start fresh each, we were told to delete our code after every session. We were in pairs, swapping after each session, and we did the same task every time. In fact, Conway’s Game of Life is the only task mentioned anywhere that I find for coderetreat. So I don’t know what we’ll do next time, or if we’re meant to do the same thing again. There are some guiding principles which felt to us like restrictions, that you have to code in crazy ways to encourage better code. Final thing is that it’s supposed to be free for outsiders to join. It’s meant to be a kind of networking thing, where you link up with people from other companies. We had a pilot day with Michael and Lauri. Since it was basically the first time any of us had done anything like this, everybody was from Red Gate. We didn’t chat to anybody else for the initial one. The task was Conway’s Game of Life, which most of you have probably heard of it, all but one of us knew about it when did the coderetreat. I won’t got into the details of what it is, but it felt like the right size of task, basically one or two groups actually produced something working by the end of the day, and of course that doesn’t mean it’s necessarily a day’s work to produce that because we were starting again every hour. The task really drives you more than trying to create good code, I found. It was really tempting to try and get it working rather than stick to the rules. But it’s really good to stop and try again because there are so many what-ifs when you’ve finished writing something, “what if I’d done it this way?”. You can answer all those questions at a coderetreat because it’s not about getting a product out the door, it’s about learning and playing with ideas. So we had all these different practices we were trying. I’ll try and go through most of these. Single responsibility is this idea that everything should do just one thing. It was the very first session, we were still trying to figure out how do you go about the Game of Life? So by the end of forty-five minutes hadn’t produced very much for that first session. We were still thinking, “Do we start with a board, how do we represent all these squares? It can be infinitely big, help, this is getting really difficult!”. So, most of us didn’t really get anywhere on the first one. Although it was interesting that some people started with the board, one group started with the FateDecider class that decides whether things live or die. A sort of god class, but in a good way. They managed to implement all of the rules without even defining how the squares were arranged or anything like that. Another thing we tried was TDD (test-driven development). I’m sure most of you know what TDD is: Watch a test, watch it fail for the right reason Write code to pass the test, watch it pass Refactor, check the test still passes Repeat! It basically worked, we were able to produce code, but we often found the tests defined the direction that code went, which is obviously the idea of TDD. But you tend to find that by the time you’ve even written your first assertion, which is supposed to be the very first thing you write, because you write your tests backwards from the assertions back to the initial conditions, you’ve already constrained the logic of the code in some way by the time you’ve done that. You then get to this situation of, “Well, we actually want to go in a slightly different direction. Can we do this?”. Can we write tests that don’t constrain the architecture? Wrapping up all primitives: it’s kind of turtles all the way down. We had a Size, which has a Width and Height, which both derive from Dimension. You’ve got pages of code before you’ve even done anything. No getters and setters (use tell don’t ask instead): mocks and stubs for tests are required if you want to assert that your results are what you think they should be. You can’t just check the internal state of the code. And people found that really challenging and it made them think in a different way which I think is really good. Not having mutable state: that was kind of confusing because we weren’t quite sure what fitted within that rule and what didn’t, and I think we were trying too hard to follow the rule rather than the guideline. No if-statements: supposed to use polymorphism instead, but polymorphism still requires a factory with conditional behaviour. We did something really crazy to get around this: public T If(bool condition, Func<T> left, Func<T> right) { var dict = new Dictionary<bool, Func<T>> {{true, left}, {false, right}}; return dict[condition].Invoke(); } That is not really polymorphism, is it? For-loops: you can always replace a for-loop with recursion, but it doesn’t tend to make it any more readable unless it’s the kind of task that really lends itself to that. So it was interesting, it was good practice, but it wouldn’t make it easier it’s the kind of tree-structure algorithm where that would help. Having a limit on the number of levels of indentation: again, I think it does produce very nice, clean code, but it wasn’t actually a challenge because you just extract methods. That’s quite a useful thing because you can apply that to real code and say, “Okay, should this method really be going crazy like this?” No talking: we hated that. It’s like there’s two of you at a computer, and one of you is doing the typing, what does the other guy do if they’re not allowed to talk. The answer is TDD ping-pong – one person writes the tests, and then the other person writes the code to pass the test. And that creates communication without actually having to have discussion about things which is kind of cool. No code comments: just makes no difference to anything. It’s a forty-five minute exercise, so what are you going to put comments in code for? Finally, this is my fault. I discovered an entertaining way of doing the calculation that was kind of cool (using convolutions over the state of the board). Unfortunately, it turns out to be really hard to implement in C#, so didn’t even manage to work out how to do that convolution in C#. It’s trivial in some high-level languages, but you need something matrix-orientated for it to really work. That’s most of it, really. The thoughts that people went away with: we put down our answers to questions like “What have you learnt?” and “What surprised you?”, “How are you going to do things differently?”, and most people said redoing the problem is really, really good for understanding it properly. People hate having a massive legacy codebase that they can’t change, so being able to attack something three different ways in an environment where the end-product isn’t important: that’s something people really enjoyed. Pair-programming: also people said that they wanted to do more of that, especially with TDD ping-pong, where you write the test and somebody else writes the code. Various people thought different things about immutables, but most people thought they were good, they promote functional programming. And TDD people found really hard. “Tell, don’t ask” people found really, really hard and really, really, really hard to do well. And the recursion just made things trickier to debug. But most people agreed that coderetreats are really cool, and we should do more of them.

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• Dual Control / Four Eyes Principle

  - by Ralf

  I have the requirement to implement some kind of Dual Control or Four-Eyes-Principle, meaning that every change of an object done by user A has to be checked by user B. A trivial example would be a publishing system where an author writes an article and another has to proofread it before it is published. I am a little bit surprised that you find nearly nothing about it on the net. No patterns, no libraries (besides cibet), no workflow solutions etc. Is this requirement really so uncommon? Or am I searching for the wrong terms? I am not looking for a specific solution. More for a pattern or best practice approach.

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• Delegates and Events in C#

  - by hakanbilge

  Events and their underlying mechanism "Delegates" are very powerful tools of a developer and Event Driven Programming is one of the main Programming Paradigms. Its wiki definition is "event-driven programming or event-based programming is a programming paradigm in which the flow of the program is determined by events?i.e., sensor outputs or user actions (mouse clicks, key presses) or messages from other programs or threads." That means, your program can go its own way sequentially and in the case of anything that requires attention is done (when an event fires) by somebody or something, you can response it by using that event's controller method (this mechanism is like interrupt driven programming in embedded systems). There are many real world scenarios for events, for example, ASP.NET uses events to catch a click on a button or in your app, controller has notice of a change in UI by handling events exposed by view (in MVC pattern). Delegates in C# C# delegates correspond to function pointers in  [read more....]

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• Primary domain in vps in vps has been deactivated

  - by manix

  This is my scenario: I have a vps with two domains (example1.com, example2.com). When I started with this vps I set example1.com as primary domain and the nameserver were configured with the pattern ns1.example.com, ns2.example1.com. The domains were brought in name.com. Across the time, I usually only work whit the domain example2.com, for that reason I stopped to pay example1.com anual registration and just keep the example2.com. But, today my vps is unreacheable because the main domain was deactivated last ago 23th. I never imagined that it could affect my server. So, I am so worried because I don't know if rebuild the vps is the solution here because I could lost my data. Can you take me to the right direction in order to recover my vps?

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• Clustering Basics and Challenges

  - by Karoly Vegh

  For upcoming posts it seemed to be a good idea to dedicate some time for cluster basic concepts and theory. This post misses a lot of details that would explode the articlesize, should you have questions, do not hesitate to ask them in the comments.  The goal here is to get some concepts straight. I can't promise to give you an overall complete definitions of cluster, cluster agent, quorum, voting, fencing, split brain condition, so the following is more of an explanation. Here we go. -------- Cluster, HA, failover, switchover, scalability -------- An attempted definition of a Cluster: A cluster is a set (2+) server nodes dedicated to keep application services alive, communicating through the cluster software/framework with eachother, test and probe health status of servernodes/services and with quorum based decisions and with switchover/failover techniques keep the application services running on them available. That is, should a node that runs a service unexpectedly lose functionality/connection, the other ones would take over the and run the services, so that availability is guaranteed. To provide availability while strictly sticking to a consistent clusterconfiguration is the main goal of a cluster.  At this point we have to add that this defines a HA-cluster, a High-Availability cluster, where the clusternodes are planned to run the services in an active-standby, or failover fashion. An example could be a single instance database. Some applications can be run in a distributed or scalable fashion. In the latter case instances of the application run actively on separate clusternodes serving servicerequests simultaneously. An example for this version could be a webserver that forwards connection requests to many backend servers in a round-robin way. Or a database running in active-active RAC setup.  -------- Cluster arhitecture, interconnect, topologies -------- Now, what is a cluster made of? Servers, right. These servers (the clusternodes) need to communicate. This of course happens over the network, usually over dedicated network interfaces interconnecting all the clusternodes. These connection are called interconnects.How many clusternodes are in a cluster? There are different cluster topologies. The most simple one is a clustered pair topology, involving only two clusternodes:  There are several more topologies, clicking the image above will take you to the relevant documentation. Also, to answer the question Solaris Cluster allows you to run up to 16 servers in a cluster. Where shall these clusternodes be placed? A very important question. The right answer is: It depends on what you plan to achieve with the cluster. Do you plan to avoid only a server outage? Then you can place them right next to eachother in the datacenter. Do you need to avoid DataCenter outage? In that case of course you should place them at least in different fire zones. Or in two geographically distant DataCenters to avoid disasters like floods, large-scale fires or power outages. We call this a stretched- or campus cluster, the clusternodes being several kilometers away from eachother. To cover really large distances, you probably need to move to a GeoCluster, which is a different kind of animal.  What is a geocluster? A Geographic Cluster in Solaris Cluster terms is actually a metacluster between two, separate (locally-HA) clusters.  -------- Cluster resource types, agents, resources, resource groups -------- So how does the cluster manage my applications? The cluster needs to start, stop and probe your applications. If you application runs, the cluster needs to check regularly if the application state is healthy, does it respond over the network, does it have all the processes running, etc. This is called probing. If the cluster deems the application is in a faulty state, then it can try to restart it locally or decide to switch (stop on node A, start on node B) the service. Starting, stopping and probing are the three actions that a cluster agent does. There are many different kinds of agents included in Solaris Cluster, but you can build your own too. Examples are an agent that manages (mounts, moves) ZFS filesystems, or the Oracle DB HA agent that cares about the database, or an agent that moves a floating IP address between nodes. There are lots of other agents included for Apache, Tomcat, MySQL, Oracle DB, Oracle Weblogic, Zones, LDoms, NFS, DNS, etc.We also need to clarify the difference between a cluster resource and the cluster resource group.A cluster resource is something that is managed by a cluster agent. Cluster resource types are included in Solaris cluster (see above, e.g. HAStoragePlus, HA-Oracle, LogicalHost). You can group cluster resources into cluster resourcegroups, and switch these groups together from one node to another. To stick to the example above, to move an Oracle DB service from one node to another, you have to switch the group between nodes, and the agents of the cluster resources in the group will do the following:  On node A Shut down the DB Unconfigure the LogicalHost IP the DB Listener listens on unmount the filesystem   Then, on node B: mount the FS configure the IP  startup the DB -------- Voting, Quorum, Split Brain Condition, Fencing, Amnesia -------- How do the clusternodes agree upon their action? How do they decide which node runs what services? Another important question. Running a cluster is a strictly democratic thing.Every node has votes, and you need the majority of votes to have the deciding power. Now, this is usually no problem, clusternodes think very much all alike. Still, every action needs to be governed upon in a productive system, and has to be agreed upon. Agreeing is easy as long as the clusternodes all behave and talk to eachother over the interconnect. But if the interconnect is gone/down, this all gets tricky and confusing. Clusternodes think like this: "My job is to run these services. The other node does not answer my interconnect communication, it must be down. I'd better take control and run the services!". The problem is, as I have already mentioned, clusternodes very much think alike. If the interconnect is gone, they all assume the other node is down, and they all want to mount the data backend, enable the IP and run the database. Double IPs, double mounts, double DB instances - now that is trouble. Also, in a 2-node cluster they both have only 50% of the votes, that is, they themselves alone are not allowed to run a cluster.  This is where you need a quorum device. According to Wikipedia, the "requirement for a quorum is protection against totally unrepresentative action in the name of the body by an unduly small number of persons.". They need additional votes to run the cluster. For this requirement a 2-node cluster needs a quorum device or a quorum server. If the interconnect is gone, (this is what we call a split brain condition) both nodes start to race and try to reserve the quorum device to themselves. They do this, because the quorum device bears an additional vote, that could ensure majority (50% +1). The one that manages to lock the quorum device (e.g. if it's an FC LUN, it SCSI reserves it) wins the right to build/run a cluster, the other one - realizing he was late - panics/reboots to ensure the cluster config stays consistent.  Losing the interconnect isn't only endangering the availability of services, but it also endangers the cluster configuration consistence. Just imagine node A being down and during that the cluster configuration changes. Now node B goes down, and node A comes up. It isn't uptodate about the cluster configuration's changes so it will refuse to start a cluster, since that would lead to cluster amnesia, that is the cluster had some changes, but now runs with an older cluster configuration repository state, that is it's like it forgot about the changes.  Also, to ensure application data consistence, the clusternode that wins the race makes sure that a server that isn't part of or can't currently join the cluster can access the devices. This procedure is called fencing. This usually happens to storage LUNs via SCSI reservation.  Now, another important question: Where do I place the quorum disk?  Imagine having two sites, two separate datacenters, one in the north of the city and the other one in the south part of it. You run a stretched cluster in the clustered pair topology. Where do you place the quorum disk/server? If you put it into the north DC, and that gets hit by a meteor, you lose one clusternode, which isn't a problem, but you also lose your quorum, and the south clusternode can't keep the cluster running lacking the votes. This problem can't be solved with two sites and a campus cluster. You will need a third site to either place the quorum server to, or a third clusternode. Otherwise, lacking majority, if you lose the site that had your quorum, you lose the cluster. Okay, we covered the very basics. We haven't talked about virtualization support, CCR, ClusterFilesystems, DID devices, affinities, storage-replication, management tools, upgrade procedures - should those be interesting for you, let me know in the comments, along with any other questions. Given enough demand I'd be glad to write a followup post too. Now I really want to move on to the second part in the series: ClusterInstallation.  Oh, as for additional source of information, I recommend the documentation: http://docs.oracle.com/cd/E23623_01/index.html, and the OTN Oracle Solaris Cluster site: http://www.oracle.com/technetwork/server-storage/solaris-cluster/index.html

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• How to mount a blu-ray drive?

  - by Stephan Schielke

  Maybe it is for the best to close this question. This has nothing to do with a bluray drive in general anymore. Probably a hardware defect. I will try to test it with a windows system and different cables again... Thx so far. I have a bluray/dvd/cdrom drive with SATA. Ubuntu wont find it under /dev/sd wodim --devices wodim: Overview of accessible drives (1 found) : ------------------------------------------------------------------------- 0 dev='/dev/sg2' rwrw-- : 'HL-DT-ST' 'BDDVDRW CH08LS10' ------------------------------------------------------------------------- cdrecord -scanbus scsibus2: 2,0,0 200) 'HL-DT-ST' 'BDDVDRW CH08LS10' '2.00' Removable CD-ROM fdisk dont even lists it. Ubuntu only automounts blank DVDs, but neither CDROM nor Blurays. I also changed the sata slot, sata cable and the power cable. The drive works with a windows system. This happens when I try to mount: sudo mount -t auto /dev/scd0 /media/bluray mount: you must specify the filesystem type I tried all filesystems there are. I also installed makemkv. It finds the drive but not the disc. Here is my /dev ls -al /dev total 12 drwxr-xr-x 17 root root 4420 2011-11-25 19:36 . drwxr-xr-x 28 root root 4096 2011-11-25 07:12 .. crw------- 1 root root 10, 235 2011-11-25 19:28 autofs -rw-r--r-- 1 root root 630 2011-11-25 19:28 .blkid.tab -rw-r--r-- 1 root root 630 2011-11-25 19:28 .blkid.tab.old drwxr-xr-x 2 root root 700 2011-11-25 19:27 block drwxr-xr-x 2 root root 100 2011-11-25 19:27 bsg crw------- 1 root root 10, 234 2011-11-25 19:28 btrfs-control drwxr-xr-x 3 root root 60 2011-11-25 19:27 bus drwxr-xr-x 2 root root 3820 2011-11-25 19:28 char crw------- 1 root root 5, 1 2011-11-25 19:28 console lrwxrwxrwx 1 root root 11 2011-11-25 19:28 core -> /proc/kcore drwxr-xr-x 2 root root 60 2011-11-25 19:28 cpu crw------- 1 root root 10, 60 2011-11-25 19:28 cpu_dma_latency drwxr-xr-x 7 root root 140 2011-11-25 19:27 disk crw------- 1 root root 10, 61 2011-11-25 19:28 ecryptfs crw-rw---- 1 root video 29, 0 2011-11-25 19:28 fb0 lrwxrwxrwx 1 root root 13 2011-11-25 19:28 fd -> /proc/self/fd crw-rw-rw- 1 root root 1, 7 2011-11-25 19:28 full crw-rw-rw- 1 root fuse 10, 229 2011-11-25 19:28 fuse crw------- 1 root root 251, 0 2011-11-25 19:28 hidraw0 crw------- 1 root root 251, 1 2011-11-25 19:28 hidraw1 crw------- 1 root root 10, 228 2011-11-25 19:28 hpet lrwxrwxrwx 1 root root 14 2011-11-25 19:27 .initramfs -> /run/initramfs drwxr-xr-x 4 root root 220 2011-11-25 19:28 input crw------- 1 root root 1, 11 2011-11-25 19:28 kmsg srw-rw-rw- 1 root root 0 2011-11-25 19:28 log brw-rw---- 1 root disk 7, 0 2011-11-25 19:28 loop0 brw-rw---- 1 root disk 7, 1 2011-11-25 19:28 loop1 brw-rw---- 1 root disk 7, 2 2011-11-25 19:28 loop2 brw-rw---- 1 root disk 7, 3 2011-11-25 19:28 loop3 brw-rw---- 1 root disk 7, 4 2011-11-25 19:28 loop4 brw-rw---- 1 root disk 7, 5 2011-11-25 19:28 loop5 brw-rw---- 1 root disk 7, 6 2011-11-25 19:28 loop6 brw-rw---- 1 root disk 7, 7 2011-11-25 19:28 loop7 drwxr-xr-x 2 root root 60 2011-11-25 19:27 mapper crw------- 1 root root 10, 227 2011-11-25 19:28 mcelog crw-r----- 1 root kmem 1, 1 2011-11-25 19:28 mem drwxr-xr-x 2 root root 60 2011-11-25 19:27 net crw------- 1 root root 10, 59 2011-11-25 19:28 network_latency crw------- 1 root root 10, 58 2011-11-25 19:28 network_throughput crw-rw-rw- 1 root root 1, 3 2011-11-25 19:28 null crw-rw-rw- 1 root root 195, 0 2011-11-25 19:28 nvidia0 crw-rw-rw- 1 root root 195, 255 2011-11-25 19:28 nvidiactl crw------- 1 root root 1, 12 2011-11-25 19:28 oldmem crw-r----- 1 root kmem 1, 4 2011-11-25 19:28 port crw------- 1 root root 108, 0 2011-11-25 19:28 ppp crw------- 1 root root 10, 1 2011-11-25 19:28 psaux crw-rw-rw- 1 root tty 5, 2 2011-11-25 20:00 ptmx drwxr-xr-x 2 root root 0 2011-11-25 19:27 pts brw-rw---- 1 root disk 1, 0 2011-11-25 19:28 ram0 brw-rw---- 1 root disk 1, 1 2011-11-25 19:28 ram1 brw-rw---- 1 root disk 1, 10 2011-11-25 19:28 ram10 brw-rw---- 1 root disk 1, 11 2011-11-25 19:28 ram11 brw-rw---- 1 root disk 1, 12 2011-11-25 19:28 ram12 brw-rw---- 1 root disk 1, 13 2011-11-25 19:28 ram13 brw-rw---- 1 root disk 1, 14 2011-11-25 19:28 ram14 brw-rw---- 1 root disk 1, 15 2011-11-25 19:28 ram15 brw-rw---- 1 root disk 1, 2 2011-11-25 19:28 ram2 brw-rw---- 1 root disk 1, 3 2011-11-25 19:28 ram3 brw-rw---- 1 root disk 1, 4 2011-11-25 19:28 ram4 brw-rw---- 1 root disk 1, 5 2011-11-25 19:28 ram5 brw-rw---- 1 root disk 1, 6 2011-11-25 19:28 ram6 brw-rw---- 1 root disk 1, 7 2011-11-25 19:28 ram7 brw-rw---- 1 root disk 1, 8 2011-11-25 19:28 ram8 brw-rw---- 1 root disk 1, 9 2011-11-25 19:28 ram9 crw-rw-rw- 1 root root 1, 8 2011-11-25 19:28 random crw-rw-r--+ 1 root root 10, 62 2011-11-25 19:28 rfkill lrwxrwxrwx 1 root root 4 2011-11-25 19:28 rtc -> rtc0 crw------- 1 root root 254, 0 2011-11-25 19:28 rtc0 lrwxrwxrwx 1 root root 3 2011-11-25 19:38 scd0 -> sr0 brw-rw---- 1 root disk 8, 0 2011-11-25 19:28 sda brw-rw---- 1 root disk 8, 1 2011-11-25 19:28 sda1 brw-rw---- 1 root disk 8, 2 2011-11-25 19:28 sda2 brw-rw---- 1 root disk 8, 3 2011-11-25 19:28 sda3 brw-rw---- 1 root disk 8, 5 2011-11-25 19:28 sda5 brw-rw---- 1 root disk 8, 6 2011-11-25 19:28 sda6 brw-rw---- 1 root disk 8, 16 2011-11-25 19:28 sdb brw-rw---- 1 root disk 8, 17 2011-11-25 19:28 sdb1 crw-rw---- 1 root disk 21, 0 2011-11-25 19:28 sg0 crw-rw---- 1 root disk 21, 1 2011-11-25 19:28 sg1 crw-rw----+ 1 root cdrom 21, 2 2011-11-25 19:28 sg2 lrwxrwxrwx 1 root root 8 2011-11-25 19:28 shm -> /run/shm crw------- 1 root root 10, 231 2011-11-25 19:28 snapshot drwxr-xr-x 4 root root 280 2011-11-25 19:28 snd brw-rw----+ 1 root cdrom 11, 0 2011-11-25 19:38 sr0 lrwxrwxrwx 1 root root 15 2011-11-25 19:28 stderr -> /proc/self/fd/2 lrwxrwxrwx 1 root root 15 2011-11-25 19:28 stdin -> /proc/self/fd/0 lrwxrwxrwx 1 root root 15 2011-11-25 19:28 stdout -> /proc/self/fd/1 crw-rw-rw- 1 root tty 5, 0 2011-11-25 19:35 tty crw--w---- 1 root tty 4, 0 2011-11-25 19:28 tty0 crw------- 1 root root 4, 1 2011-11-25 19:28 tty1 crw--w---- 1 root tty 4, 10 2011-11-25 19:28 tty10 crw--w---- 1 root tty 4, 11 2011-11-25 19:28 tty11 crw--w---- 1 root tty 4, 12 2011-11-25 19:28 tty12 crw--w---- 1 root tty 4, 13 2011-11-25 19:28 tty13 crw--w---- 1 root tty 4, 14 2011-11-25 19:28 tty14 crw--w---- 1 root tty 4, 15 2011-11-25 19:28 tty15 crw--w---- 1 root tty 4, 16 2011-11-25 19:28 tty16 crw--w---- 1 root tty 4, 17 2011-11-25 19:28 tty17 crw--w---- 1 root tty 4, 18 2011-11-25 19:28 tty18 crw--w---- 1 root tty 4, 19 2011-11-25 19:28 tty19 crw------- 1 root root 4, 2 2011-11-25 19:28 tty2 crw--w---- 1 root tty 4, 20 2011-11-25 19:28 tty20 crw--w---- 1 root tty 4, 21 2011-11-25 19:28 tty21 crw--w---- 1 root tty 4, 22 2011-11-25 19:28 tty22 crw--w---- 1 root tty 4, 23 2011-11-25 19:28 tty23 crw--w---- 1 root tty 4, 24 2011-11-25 19:28 tty24 crw--w---- 1 root tty 4, 25 2011-11-25 19:28 tty25 crw--w---- 1 root tty 4, 26 2011-11-25 19:28 tty26 crw--w---- 1 root tty 4, 27 2011-11-25 19:28 tty27 crw--w---- 1 root tty 4, 28 2011-11-25 19:28 tty28 crw--w---- 1 root tty 4, 29 2011-11-25 19:28 tty29 crw------- 1 root root 4, 3 2011-11-25 19:28 tty3 crw--w---- 1 root tty 4, 30 2011-11-25 19:28 tty30 crw--w---- 1 root tty 4, 31 2011-11-25 19:28 tty31 crw--w---- 1 root tty 4, 32 2011-11-25 19:28 tty32 crw--w---- 1 root tty 4, 33 2011-11-25 19:28 tty33 crw--w---- 1 root tty 4, 34 2011-11-25 19:28 tty34 crw--w---- 1 root tty 4, 35 2011-11-25 19:28 tty35 crw--w---- 1 root tty 4, 36 2011-11-25 19:28 tty36 crw--w---- 1 root tty 4, 37 2011-11-25 19:28 tty37 crw--w---- 1 root tty 4, 38 2011-11-25 19:28 tty38 crw--w---- 1 root tty 4, 39 2011-11-25 19:28 tty39 crw------- 1 root root 4, 4 2011-11-25 19:28 tty4 crw--w---- 1 root tty 4, 40 2011-11-25 19:28 tty40 crw--w---- 1 root tty 4, 41 2011-11-25 19:28 tty41 crw--w---- 1 root tty 4, 42 2011-11-25 19:28 tty42 crw--w---- 1 root tty 4, 43 2011-11-25 19:28 tty43 crw--w---- 1 root tty 4, 44 2011-11-25 19:28 tty44 crw--w---- 1 root tty 4, 45 2011-11-25 19:28 tty45 crw--w---- 1 root tty 4, 46 2011-11-25 19:28 tty46 crw--w---- 1 root tty 4, 47 2011-11-25 19:28 tty47 crw--w---- 1 root tty 4, 48 2011-11-25 19:28 tty48 crw--w---- 1 root tty 4, 49 2011-11-25 19:28 tty49 crw------- 1 root root 4, 5 2011-11-25 19:28 tty5 crw--w---- 1 root tty 4, 50 2011-11-25 19:28 tty50 crw--w---- 1 root tty 4, 51 2011-11-25 19:28 tty51 crw--w---- 1 root tty 4, 52 2011-11-25 19:28 tty52 crw--w---- 1 root tty 4, 53 2011-11-25 19:28 tty53 crw--w---- 1 root tty 4, 54 2011-11-25 19:28 tty54 crw--w---- 1 root tty 4, 55 2011-11-25 19:28 tty55 crw--w---- 1 root tty 4, 56 2011-11-25 19:28 tty56 crw--w---- 1 root tty 4, 57 2011-11-25 19:28 tty57 crw--w---- 1 root tty 4, 58 2011-11-25 19:28 tty58 crw--w---- 1 root tty 4, 59 2011-11-25 19:28 tty59 crw------- 1 root root 4, 6 2011-11-25 19:28 tty6 crw--w---- 1 root tty 4, 60 2011-11-25 19:28 tty60 crw--w---- 1 root tty 4, 61 2011-11-25 19:28 tty61 crw--w---- 1 root tty 4, 62 2011-11-25 19:28 tty62 crw--w---- 1 root tty 4, 63 2011-11-25 19:28 tty63 crw--w---- 1 root tty 4, 7 2011-11-25 19:28 tty7 crw--w---- 1 root tty 4, 8 2011-11-25 19:28 tty8 crw--w---- 1 root tty 4, 9 2011-11-25 19:28 tty9 crw------- 1 root root 5, 3 2011-11-25 19:28 ttyprintk crw-rw---- 1 root dialout 4, 64 2011-11-25 19:28 ttyS0 crw-rw---- 1 root dialout 4, 65 2011-11-25 19:28 ttyS1 crw-rw---- 1 root dialout 4, 74 2011-11-25 19:28 ttyS10 crw-rw---- 1 root dialout 4, 75 2011-11-25 19:28 ttyS11 crw-rw---- 1 root dialout 4, 76 2011-11-25 19:28 ttyS12 crw-rw---- 1 root dialout 4, 77 2011-11-25 19:28 ttyS13 crw-rw---- 1 root dialout 4, 78 2011-11-25 19:28 ttyS14 crw-rw---- 1 root dialout 4, 79 2011-11-25 19:28 ttyS15 crw-rw---- 1 root dialout 4, 80 2011-11-25 19:28 ttyS16 crw-rw---- 1 root dialout 4, 81 2011-11-25 19:28 ttyS17 crw-rw---- 1 root dialout 4, 82 2011-11-25 19:28 ttyS18 crw-rw---- 1 root dialout 4, 83 2011-11-25 19:28 ttyS19 crw-rw---- 1 root dialout 4, 66 2011-11-25 19:28 ttyS2 crw-rw---- 1 root dialout 4, 84 2011-11-25 19:28 ttyS20 crw-rw---- 1 root dialout 4, 85 2011-11-25 19:28 ttyS21 crw-rw---- 1 root dialout 4, 86 2011-11-25 19:28 ttyS22 crw-rw---- 1 root dialout 4, 87 2011-11-25 19:28 ttyS23 crw-rw---- 1 root dialout 4, 88 2011-11-25 19:28 ttyS24 crw-rw---- 1 root dialout 4, 89 2011-11-25 19:28 ttyS25 crw-rw---- 1 root dialout 4, 90 2011-11-25 19:28 ttyS26 crw-rw---- 1 root dialout 4, 91 2011-11-25 19:28 ttyS27 crw-rw---- 1 root dialout 4, 92 2011-11-25 19:28 ttyS28 crw-rw---- 1 root dialout 4, 93 2011-11-25 19:28 ttyS29 crw-rw---- 1 root dialout 4, 67 2011-11-25 19:28 ttyS3 crw-rw---- 1 root dialout 4, 94 2011-11-25 19:28 ttyS30 crw-rw---- 1 root dialout 4, 95 2011-11-25 19:28 ttyS31 crw-rw---- 1 root dialout 4, 68 2011-11-25 19:28 ttyS4 crw-rw---- 1 root dialout 4, 69 2011-11-25 19:28 ttyS5 crw-rw---- 1 root dialout 4, 70 2011-11-25 19:28 ttyS6 crw-rw---- 1 root dialout 4, 71 2011-11-25 19:28 ttyS7 crw-rw---- 1 root dialout 4, 72 2011-11-25 19:28 ttyS8 crw-rw---- 1 root dialout 4, 73 2011-11-25 19:28 ttyS9 d rwxr-xr-x 3 root root 60 2011-11-25 19:28 .udev crw-r----- 1 root root 10, 223 2011-11-25 19:28 uinput crw-rw-rw- 1 root root 1, 9 2011-11-25 19:28 urandom drwxr-xr-x 2 root root 60 2011-11-25 19:27 usb crw------- 1 root root 252, 0 2011-11-25 19:28 usbmon0 crw------- 1 root root 252, 1 2011-11-25 19:28 usbmon1 crw------- 1 root root 252, 2 2011-11-25 19:28 usbmon2 crw------- 1 root root 252, 3 2011-11-25 19:28 usbmon3 crw------- 1 root root 252, 4 2011-11-25 19:28 usbmon4 crw------- 1 root root 252, 5 2011-11-25 19:28 usbmon5 crw------- 1 root root 252, 6 2011-11-25 19:28 usbmon6 crw------- 1 root root 252, 7 2011-11-25 19:28 usbmon7 crw------- 1 root root 252, 8 2011-11-25 19:28 usbmon8 drwxr-xr-x 4 root root 80 2011-11-25 19:28 v4l crw------- 1 root root 10, 57 2011-11-25 19:28 vboxdrv crw------- 1 root root 10, 56 2011-11-25 19:28 vboxnetctl drwxr-x--- 4 root vboxusers 80 2011-11-25 19:28 vboxusb crw-rw---- 1 root tty 7, 0 2011-11-25 19:28 vcs crw-rw---- 1 root tty 7, 1 2011-11-25 19:28 vcs1 crw-rw---- 1 root tty 7, 2 2011-11-25 19:28 vcs2 crw-rw---- 1 root tty 7, 3 2011-11-25 19:28 vcs3 crw-rw---- 1 root tty 7, 4 2011-11-25 19:28 vcs4 crw-rw---- 1 root tty 7, 5 2011-11-25 19:28 vcs5 crw-rw---- 1 root tty 7, 6 2011-11-25 19:28 vcs6 crw-rw---- 1 root tty 7, 128 2011-11-25 19:28 vcsa crw-rw---- 1 root tty 7, 129 2011-11-25 19:28 vcsa1 crw-rw---- 1 root tty 7, 130 2011-11-25 19:28 vcsa2 crw-rw---- 1 root tty 7, 131 2011-11-25 19:28 vcsa3 crw-rw---- 1 root tty 7, 132 2011-11-25 19:28 vcsa4 crw-rw---- 1 root tty 7, 133 2011-11-25 19:28 vcsa5 crw-rw---- 1 root tty 7, 134 2011-11-25 19:28 vcsa6 crw------- 1 root root 10, 63 2011-11-25 19:28 vga_arbiter crw-rw----+ 1 root video 81, 0 2011-11-25 19:28 video0 crw-rw-rw- 1 root root 1, 5 2011-11-25 19:28 zero sg_scan -i gives me: sudo sg_scan -i /dev/sg0: scsi0 channel=0 id=0 lun=0 [em] ATA ST31000524NS SN12 [rmb=0 cmdq=0 pqual=0 pdev=0x0] /dev/sg1: scsi0 channel=0 id=1 lun=0 [em] ATA WDC WD15EADS-00S 01.0 [rmb=0 cmdq=0 pqual=0 pdev=0x0] /dev/sg2: scsi2 channel=0 id=0 lun=0 [em] HL-DT-ST BDDVDRW CH08LS10 2.00 [rmb=1 cmdq=0 pqual=0 pdev=0x5] sg_map gives me: /dev/sg0 /dev/sda /dev/sg1 /dev/sdb /dev/sg2 /dev/scd0 lsscsi -l gives me: [0:0:0:0] disk ATA ST31000524NS SN12 /dev/sda state=running queue_depth=1 scsi_level=6 type=0 device_blocked=0 timeout=30 [0:0:1:0] disk ATA WDC WD15EADS-00S 01.0 /dev/sdb state=running queue_depth=1 scsi_level=6 type=0 device_blocked=0 timeout=30 [2:0:0:0] cd/dvd HL-DT-ST BDDVDRW CH08LS10 2.00 /dev/sr0 state=running queue_depth=1 scsi_level=6 type=5 device_blocked=0 timeout=30 my udf mod is: filename: /lib/modules/3.0.0-14-generic/kernel/fs/udf/udf.ko license: GPL description: Universal Disk Format Filesystem author: Ben Fennema srcversion: 6ABDE012374D96B9685B8E5 depends: crc-itu-t vermagic: 3.0.0-14-generic SMP mod_unload modversions Do I need special drivers or mods enabled? Do I need to change some BIOS settings? edit: Somehow I am now able to fire the mount command without any filesystem errors, but now I get: mount: no medium found on /dev/sr0

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• Routing to a Controller with no View in Angular

  - by Rick Strahl

  I've finally had some time to put Angular to use this week in a small project I'm working on for fun. Angular's routing is great and makes it real easy to map URL routes to controllers and model data into views. But what if you don't actually need a view, if you effectively need a headless controller that just runs code, but doesn't render a view?Preserve the ViewWhen Angular navigates a route and and presents a new view, it loads the controller and then renders the view from scratch. Views are not cached or stored, but displayed and then removed. So if you have routes configured like this:'use strict'; // Declare app level module which depends on filters, and services window.myApp = angular.module('myApp', ['myApp.filters', 'myApp.services', 'myApp.directives', 'myApp.controllers']). config(['$routeProvider', function($routeProvider) { $routeProvider.when('/map', { template: "partials/map.html ", controller: 'mapController', reloadOnSearch: false, animation: 'slide' }); … $routeProvider.otherwise({redirectTo: '/map'}); }]); Angular routes to the mapController and then re-renders the map.html template with the new data from the $scope filled in.But, but… I don't want a new View!Now in most cases this works just fine. If I'm rendering plain DOM content, or textboxes in a form interface that is all fine and dandy - it's perfectly fine to completely re-render the UI.But in some cases, the UI that's being managed has state and shouldn't be redrawn. In this case the main page in question has a Google Map on it. The map is  going to be manipulated throughout the lifetime of the application and the rest of the pages. In my application I have a toolbar on the bottom and the rest of the content is replaced/switched out by the Angular Views:The problem is that the map shouldn't be redrawn each time the Location view is activated. It should maintain its state, such as the current position selected (which can move), and shouldn't redraw due to the overhead of re-rendering the initial map.Originally I set up the map, exactly like all my other views - as a partial, that is rendered with a separate file, but that didn't work.The Workaround - Controller Only RoutesThe workaround for this goes decidedly against Angular's way of doing things:Setting up a Template-less RouteIn-lining the map view directly into the main pageHiding and showing the map view manuallyLet's see how this works.Controller Only RouteThe template-less route is basically a route that doesn't have any template to render. This is not directly supported by Angular, but thankfully easy to fake. The end goal here is that I want to simply have the Controller fire and then have the controller manage the display of the already active view by hiding and showing the map and any other view content, in effect bypassing Angular's view display management.In short - I want a controller action, but no view rendering.The controller-only or template-less route looks like this: $routeProvider.when('/map', { template: " ", // just fire controller controller: 'mapController', animation: 'slide' });Notice I'm using the template property rather than templateUrl (used in the first example above), which allows specifying a string template, and leaving it blank. The template property basically allows you to provide a templated string using Angular's HandleBar like binding syntax which can be useful at times. You can use plain strings or strings with template code in the template, or as I'm doing here a blank string to essentially fake 'just clear the view'. In-lined ViewSo if there's no view where does the HTML go? Because I don't want Angular to manage the view the map markup is in-lined directly into the page. So instead of rendering the map into the Angular view container, the content is simply set up as inline HTML to display as a sibling to the view container.<div id="MapContent" data-icon="LocationIcon" ng-controller="mapController" style="display:none"> <div class="headerbar"> <div class="right-header" style="float:right"> <a id="btnShowSaveLocationDialog" class="iconbutton btn btn-sm" href="#/saveLocation" style="margin-right: 2px;"> <i class="icon-ok icon-2x" style="color: lightgreen; "></i> Save Location </a> </div> <div class="left-header">GeoCrumbs</div> </div> <div class="clearfix"></div> <div id="Message"> <i id="MessageIcon"></i> <span id="MessageText"></span> </div> <div id="Map" class="content-area"> </div> </div> <div id="ViewPlaceholder" ng-view></div>Note that there's the #MapContent element and the #ViewPlaceHolder. The #MapContent is my static map view that is always 'live' and is initially hidden. It is initially hidden and doesn't get made visible until the MapController controller activates it which does the initial rendering of the map. After that the element is persisted with the map data already loaded and any future access only updates the map with new locations/pins etc.Note that default route is assigned to the mapController, which means that the mapController is fired right as the page loads, which is actually a good thing in this case, as the map is the cornerstone of this app that is manipulated by some of the other controllers/views.The Controller handles some UISince there's effectively no view activation with the template-less route, the controller unfortunately has to take over some UI interaction directly. Specifically it has to swap the hidden state between the map and any of the other views.Here's what the controller looks like:myApp.controller('mapController', ["$scope", "$routeParams", "locationData", function($scope, $routeParams, locationData) { $scope.locationData = locationData.location; $scope.locationHistory = locationData.locationHistory; if ($routeParams.mode == "currentLocation") { bc.getCurrentLocation(false); } bc.showMap(false,"#LocationIcon"); }]);bc.showMap is responsible for a couple of display tasks that hide/show the views/map and for activating/deactivating icons. The code looks like this:this.showMap = function (hide,selActiveIcon) { if (!hide) $("#MapContent").show(); else { $("#MapContent").hide(); } self.fitContent(); if (selActiveIcon) { $(".iconbutton").removeClass("active"); $(selActiveIcon).addClass("active"); } };Each of the other controllers in the app also call this function when they are activated to basically hide the map and make the View Content area visible. The map controller makes the map.This is UI code and calling this sort of thing from controllers is generally not recommended, but I couldn't figure out a way using directives to make this work any more easily than this. It'd be easy to hide and show the map and view container using a flag an ng-show, but it gets tricky because of scoping of the $scope. I would have to resort to storing this setting on the $rootscope which I try to avoid. The same issues exists with the icons.It sure would be nice if Angular had a way to explicitly specify that a View shouldn't be destroyed when another view is activated, so currently this workaround is required. Searching around, I saw a number of whacky hacks to get around this, but this solution I'm using here seems much easier than any of that I could dig up even if it doesn't quite fit the 'Angular way'.Angular nice, until it's notOverall I really like Angular and the way it works although it took me a bit of time to get my head around how all the pieces fit together. Once I got the idea how the app/routes, the controllers and views snap together, putting together Angular pages becomes fairly straightforward. You can get quite a bit done never going beyond those basics. For most common things Angular's default routing and view presentation works very well.But, when you do something a bit more complex, where there are multiple dependencies or as in this case where Angular doesn't appear to support a feature that's absolutely necessary, you're on your own. Finding information on more advanced topics is not trivial especially since versions are changing so rapidly and the low level behaviors are changing frequently so finding something that works is often an exercise in trial and error. Not that this is surprising. Angular is a complex piece of kit as are all the frameworks that try to hack JavaScript into submission to do something that it was really never designed to. After all everything about a framework like Angular is an elaborate hack. A lot of shit has to happen to make this all work together and at that Angular (and Ember, Durandel etc.) are pretty amazing pieces of JavaScript code. So no harm, no foul, but I just can't help feeling like working in toy sandbox at times :-)© Rick Strahl, West Wind Technologies, 2005-2013Posted in Angular  JavaScript   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Are There Any Examples of Uncle Bob's High-Falutin' Architecture?

  - by Jordan

  I just finished watching this presentation by Uncle Bob (as well as his "Architecture" section of his "Clean Code" videos), but I'm left wondering: Are there any examples out there of applications that implement this Entity-Boundary-Interactor (or Entity-Boundary-Controller) structure? At one point I downloaded the source code to FitNesse (the acceptance testing project he mentions often as an example of not only high test coverage but good architecture, since they were able to defer the decision to not use a database until the very end), and based on a quick glance of it it appears even this project doesn't seem to fit this pattern. Are there any nontrivial examples of this architecture out in the wild, or should I not bother even looking into it and chalk it up as "it would be great if you could get there, but nobody really does"?

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• Workarounds for supporting MVVM in the Silverlight TreeView Control

  - by cibrax

  MVVM (Model-View-ViewModel) is the pattern that you will typically choose for building testable user interfaces either in WPF or Silverlight. This pattern basically relies on the data binding support in those two technologies for mapping an existing model class (the view model) to the different parts of the UI or view. Unfortunately, MVVM was not threated as first citizen for some of controls released out of the box in the Silverlight runtime or the Silverlight toolkit. That means that using data binding for implementing MVVM is not always something trivial and usually requires some customization in the existing controls. In ran into different problems myself trying to fully support data binding in controls like the tree view or the context menu or things like drag & drop.  For that reason, I decided to write this post to show how the tree view control or the tree view items can be customized to support data binding in many of its properties. In first place, you will typically use a tree view for showing hierarchical data so the view model somehow must reflect that hierarchy. An easy way to implement hierarchy in a model is to use a base item element like this one, public abstract class TreeItemModel { public abstract IEnumerable<TreeItemModel> Children; } You can later derive your concrete model classes from that base class. For example, public class CustomerModel { public string FullName { get; set; } public string Address { get; set; } public IEnumerable<OrderModel> Orders { get; set; } }   public class CustomerTreeItemModel : TreeItemModel { public CustomerTreeItemModel(CustomerModel customer) { }   public override IEnumerable<TreeItemModel> Children { get { // Return orders } } } The Children property in the CustomerTreeItem model implementation can return for instance an ObservableCollection<TreeItemModel> with the orders, so the tree view will automatically subscribe to all the changes in the collection. You can bind this model to the tree view control in the UI by using a Hierarchical data template. <e:TreeView x:Name="TreeView" ItemsSource="{Binding Customers}"> <e:TreeView.ItemTemplate> <sdk:HierarchicalDataTemplate ItemsSource="{Binding Children}"> <!-- TEMPLATE --> </sdk:HierarchicalDataTemplate> </e:TreeView.ItemTemplate> </e:TreeView> An interesting behavior with the Children property and the Hierarchical data template is that the Children property is only invoked before the expansion, so you can use lazy load at this point (The tree view control will not expand the whole tree in the first expansion). The problem with using MVVM in this control is that you can not bind properties in model with specific properties of the TreeView item such as IsSelected or IsExpanded. Here is where you need to customize the existing tree view control to support data binding in tree items. public class CustomTreeView : TreeView { public CustomTreeView() { }   protected override DependencyObject GetContainerForItemOverride() { CustomTreeViewItem tvi = new CustomTreeViewItem(); Binding expandedBinding = new Binding("IsExpanded"); expandedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsExpandedProperty, expandedBinding); Binding selectedBinding = new Binding("IsSelected"); selectedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsSelectedProperty, selectedBinding); return tvi; } }   public class CustomTreeViewItem : TreeViewItem { public CustomTreeViewItem() { }   protected override DependencyObject GetContainerForItemOverride() { CustomTreeViewItem tvi = new CustomTreeViewItem(); Binding expandedBinding = new Binding("IsExpanded"); expandedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsExpandedProperty, expandedBinding); Binding selectedBinding = new Binding("IsSelected"); selectedBinding.Mode = BindingMode.TwoWay; tvi.SetBinding(CustomTreeViewItem.IsSelectedProperty, selectedBinding); return tvi; } } You basically need to derive the TreeView and TreeViewItem controls to manually add a binding for the properties you need. In the example above, I am adding a binding for the “IsExpanded” and “IsSelected” properties in the items. The model for the tree items now needs to be extended to support those properties as well, public abstract class TreeItemModel : INotifyPropertyChanged { bool isExpanded = false; bool isSelected = false;   public abstract IEnumerable<TreeItemModel> Children { get; }   public bool IsExpanded { get { return isExpanded; } set { isExpanded = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsExpanded")); } }   public bool IsSelected { get { return isSelected; } set { isSelected = value; if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("IsSelected")); } }   public event PropertyChangedEventHandler PropertyChanged; } However, as soon as you use this custom tree view control, you lose all the automatic styles from the built-in toolkit themes because they are tied to the control type (TreeView in this case).  The only ugly workaround I found so far for this problem is to copy the styles from the Toolkit source code and reuse them in the application.

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• Dissecting ASP.NET Routing

  The ASP.NET Routing framework allows developers to decouple the URL of a resource from the physical file on the web server. Specifically, the developer defines <i>routing rules</i>, which map URL patterns to a class or ASP.NET page that generates the content. For instance, you could create a URL pattern of the form <code>Categories/<i>CategoryName</i></code> and map it to the ASP.NET page <code>ShowCategoryDetails.aspx</code>; the <code>ShowCategoryDetails.aspx</code> page would display details about the category <i>CategoryName</i>. With such a mapping, users could view category about the Beverages category by visiting <code>www.yoursite.com/Categories/Beverages</code>. In short, ASP.NET Routing allows

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• How to make Rect of irregular shape sprite?

  - by Anil gupta

  I used masking for breaking an image as the below mention pattern now its breaking in different pieces but now i have one issue to make the Rect of each pieces, i need to drag the broken pieces and to adjust at correct position so that i can make again actual images. To drag and put at right positing i need to make Rect but i am not getting idea how to make Rect of this irregular shape, I will be very thankful to you, any idea or code to make rect . My previous Question is: How do I break an image into 6 or 8 pieces of different shapes? Thanks.

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• When should I use—and not use—design patterns?

  - by ashmish2

  In a previous question of mine on Stack Overflow, FredOverflow mentioned in the comments: Note that patterns do not magically improve the quality of your code. and Any measure of quality you can imagine. Patterns are not a panacea. I once wrote a Tetris game with about 100 classes that incorporated all the patterns I knew at the time. Why use a simple if/else if you can use a pattern? OO is good, and patterns are even better, right? No, it was a terrible, over-engineered piece of crap. I am quite confused by these comments: I know design patterns help to make code reusable and readable, but when should I use use design patterns and perhaps more importantly, when should I avoid getting carried away with them?

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• Oracle Fusion Applications User Experience Design Patterns: Feeling the Love after Launch

  - by mvaughan

  By Misha Vaughan, Oracle Applications User ExperienceIn the first video by the Oracle Applications User Experience team on the Oracle Partner Network, Vice President Jeremy Ashley said that Oracle is looking to expand the ecosystem of support for Oracle’s applications customers as they begin to assess their investment and adoption of Oracle Fusion Applications. Oracle has made a massive investment to maintain the benefits of the Fusion Applications User Experience. This summer, the Applications User Experience team released the Oracle Fusion Applications user experience design patterns.Design patterns help create consistent experiences across devices.The launch has been very well received:Angelo Santagata, Senior Principal Technologist and Fusion Middleware evangelist for Oracle,  wrote this to the system integrator community: “The web site is the result of many years of Oracle R&D into user interface design for Fusion Applications and features a really cool web app which allows you to visualise the UI components in action.”  Grant Ronald, Director of Product Management, Application Development Framework (ADF) said: “It’s a science I don't understand, but now I don't have to ... Now you can learn from the UX experience of Fusion Applications.”Frank Nimphius, Senior Principal Product Manager, Oracle (ADF) wrote about the launch of the design patterns for the ADF Code Corner, and Jürgen Kress, Senior Manager EMEA Alliances & Channels for Fusion MiddleWare and Service Oriented Architecture, (SOA), shared the news with his Partner Community. Oracle Twitter followers also helped spread the message about the design patterns launch: ?@bex – Brian Huff, founder and Chief Software Architect for Bezzotech, and Oracle ACE Director:“Nifty! The Oracle Fusion UX team just released new ADF design patterns.”@maiko_rocha, Maiko Rocha, Oracle Consulting Solutions Architect and Oracle FMW engineer: “Haven't seen any other vendor offer such comprehensive UX Design Patterns catalog for free!”@zirous_chad, Chad Thompson, Senior Solutions Architect for Zirous, Inc. and ADF Developer:Wow - @ultan and company did a great job with the Fusion UX PatternsWhat is a user experience design pattern?A user experience design pattern is a re-usable, usability tested functional blueprint for a particular user experience.  Some examples are guided processes, shopping carts, and search and search results.  Ultan O’Broin discusses the top design patterns every developer should know.The patterns that were just released are based on thousands of hours of end-user field studies, state-of-the-art user interface assessments, and usability testing.  To be clear, these are functional design patterns, not technical design patterns that developers may be used to working with.  Because we know there is a gap, we are putting together some training that will help close that gap.Who should care?This is an offering targeted primarily at Application Development Framework (ADF) developers. If you are faced with the following questions regarding Fusion Applications, you will want to know and learn more:•    How do I build something that looks like Fusion Applications?•    How do I build a next-generation application?•    How do I extend a Fusion Application and maintain the user experience?•    I don’t want to re-invent the wheel on the user interface, so where do I start?•    I need to build something that will eventually co-exist with Fusion Applications. How do I do that?These questions are relevant to partners with an ADF competency, individual practitioners, or small consultancies with an ADF specialization, and customers who are trying to shift their IT staff over to supporting Fusion Applications.Where you can find out more?OnlineOur Fusion User Experience design patterns maven is Ultan O’Broin. The Oracle Partner Network is helping our team bring this first e-seminar to you in order to go into a more detail on what this means and how to take advantage of it:? Webinar: Build a Better User Experience with Oracle: Oracle Fusion Applications Functional Design PatternsSept 20, 2012 , 10:30am-11:30am PacificDial-In:  1. 877-664-9137 / Passcode 102546?International:  706-634-9619  http://www.intercall.com/national/oracleuniversity/gdnam.htmlAccess the Live Event Or Via Webconference Access http://ouweb.webex.com  ?and enter this session number: 598036234At a Usergroup eventThe Fusion User Experience Advocates (FXA) are also going to be getting some deep-dive training on this content and can share it with local user groups.At OpenWorld Ultan O’Broin               Chris MuirIf you will be at OpenWorld this year, our own Ultan O’Broin will be visiting the ADF demopod to say hello, thanks to Shay Shmeltzer, Senior Group Manager for ADF outbound communication and at the OTN lounge: Monday 10-10:45, Tuesday 2:15-2:45, Wednesday 2:15-3:30 ?  Oracle JDeveloper and Oracle ADF,  Moscone South, Right - S-207? “ADF Meet and Greett”, OTN Lounge, Wednesday 4:30 And I cannot talk about OpenWorld and ADF without mentioning Chris Muir’s ADF EMG event: the Year After the Year Of the ADF Developer – Sunday, Sept 30 of OpenWorld. Chris has played host to Ultan and the Applications user experience message for his online community and is now a seasoned UX expert.Expect to see additional announcements about expanded and training on similar topics in the future.

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• F# for the C# Programmer

  - by mbcrump

  Are you a C# Programmer and can’t make it past a day without seeing or hearing someone mention F#?  Today, I’m going to walk you through your first F# application and give you a brief introduction to the language. Sit back this will only take about 20 minutes. Introduction Microsoft's F# programming language is a functional language for the .NET framework that was originally developed at Microsoft Research Cambridge by Don Syme. In October 2007, the senior vice president of the developer division at Microsoft announced that F# was being officially productized to become a fully supported .NET language and professional developers were hired to create a team of around ten people to build the product version. In September 2008, Microsoft released the first Community Technology Preview (CTP), an official beta release, of the F# distribution . In December 2008, Microsoft announced that the success of this CTP had encouraged them to escalate F# and it is now will now be shipped as one of the core languages in Visual Studio 2010 , alongside C++, C# 4.0 and VB. The F# programming language incorporates many state-of-the-art features from programming language research and ossifies them in an industrial strength implementation that promises to revolutionize interactive, parallel and concurrent programming. Advantages of F# F# is the world's first language to combine all of the following features: Type inference: types are inferred by the compiler and generic definitions are created automatically. Algebraic data types: a succinct way to represent trees. Pattern matching: a comprehensible and efficient way to dissect data structures. Active patterns: pattern matching over foreign data structures. Interactive sessions: as easy to use as Python and Mathematica. High performance JIT compilation to native code: as fast as C#. Rich data structures: lists and arrays built into the language with syntactic support. Functional programming: first-class functions and tail calls. Expressive static type system: finds bugs during compilation and provides machine-verified documentation. Sequence expressions: interrogate huge data sets efficiently. Asynchronous workflows: syntactic support for monadic style concurrent programming with cancellations. Industrial-strength IDE support: multithreaded debugging, and graphical throwback of inferred types and documentation. Commerce friendly design and a viable commercial market. Lets try a short program in C# then F# to understand the differences. Using C#: Create a variable and output the value to the console window: Sample Program. using System;   namespace ConsoleApplication9 {     class Program     {         static void Main(string[] args)         {             var a = 2;             Console.WriteLine(a);             Console.ReadLine();         }     } } A breeze right? 14 Lines of code. We could have condensed it a bit by removing the “using” statment and tossing the namespace. But this is the typical C# program. Using F#: Create a variable and output the value to the console window: To start, open Visual Studio 2010 or Visual Studio 2008. Note: If using VS2008, then please download the SDK first before getting started. If you are using VS2010 then you are already setup and ready to go. So, click File-> New Project –> Other Languages –> Visual F# –> Windows –> F# Application. You will get the screen below. Go ahead and enter a name and click OK. Now, you will notice that the Solution Explorer contains the following: Double click the Program.fs and enter the following information. Hit F5 and it should run successfully. Sample Program. open System let a = 2        Console.WriteLine a As Shown below: Hmm, what? F# did the same thing in 3 lines of code. Show me the interactive evaluation that I keep hearing about. The F# development environment for Visual Studio 2010 provides two different modes of execution for F# code: Batch compilation to a .NET executable or DLL. (This was accomplished above). Interactive evaluation. (Demo is below) The interactive session provides a > prompt, requires a double semicolon ;; identifier at the end of a code snippet to force evaluation, and returns the names (if any) and types of resulting definitions and values. To access the F# prompt, in VS2010 Goto View –> Other Window then F# Interactive. Once you have the interactive window type in the following expression: 2+3;; as shown in the screenshot below: I hope this guide helps you get started with the language, please check out the following books for further information. F# Books for further reading   Foundations of F# Author: Robert Pickering An introduction to functional programming with F#. Including many samples, this book walks through the features of the F# language and libraries, and covers many of the .NET Framework features which can be leveraged with F#.       Functional Programming for the Real World: With Examples in F# and C# Authors: Tomas Petricek and Jon Skeet An introduction to functional programming for existing C# developers written by Tomas Petricek and Jon Skeet. This book explains the core principles using both C# and F#, shows how to use functional ideas when designing .NET applications and presents practical examples such as design of domain specific language, development of multi-core applications and programming of reactive applications.

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