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  • Watching Green Day and discovering Sitecore, priceless.

    - by jonel
    I’m feeling inspired and I’d like to share a technique we’ve implemented in Sitecore to address a URL mapping from our legacy site that we wanted to carry over to the new beautiful Littelfuse.com. The challenge is to carry over all of our series URLs that have been published in our datasheets, we currently have a lot of series and having to create a manual mapping for those could be really tedious. It has the format of http://www.littelfuse.com/series/series-name.html, for instance, http://www.littelfuse.com/series/flnr.html. It would have been easier if we have our information architecture defined like this but that would have been too easy. I took a solution that is 2-fold. First, I need to create a URL rewrite rule using the IIS URL Rewrite Module 2.0. Secondly, we need to implement a handler that will take care of the actual lookup of the actual series. It will be amazing after we’ve gone over the details. Let’s start with the URL rewrite. Create a new blank rule, you can name it with anything you wish. The key part here to talk about is the Pattern and the Action groups. The Pattern is nothing but regex. Basically, I’m telling it to match the regex I have defined. In the Action group, I am telling it what to do, in this case, rewrite to the redirect.aspx webform. In this implementation, I will be using Rewrite instead of redirect so the URL sticks in the browser. If you opt to use Redirect, then the URL bar will display the new URL our webform will redirect to. Let me explain one small thing, the (\w+) in my Pattern group’s regex, will actually translate to {R:1} in my Action’s group. This is where the magic begins. Now let’s see what our Redirect.aspx contains. Remember our {R:1} above which becomes the query string variable s? This are basic .Net code. The only thing that you will probably ask is the LFSearch class. It’s our own implementation of addressing finding items by using a field search, we supply the fieldname, the value of the field, the template name of the item we are after, and the value of true or false if we want to do an exact search, or not. If eureka, then redirect to that item’s Path (Url). If not, tell the user tough luck, here’s the 404 page as a consolation. Amazing, ain’t it?

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  • Entity Framework and Plain Old CLR Objects in an ASP.Net application

    - by nikolaosk
    This is going to be the sixth post of a series of posts regarding ASP.Net and the Entity Framework and how we can use Entity Framework to access our datastore. You can find the first one here , the second one here and the third one here , the fourth one here and the fifth one here . I have a post regarding ASP.Net and EntityDataSource. You can read it here .I have 3 more posts on Profiling Entity Framework applications. You can have a look at them here , here and here . In this post I will be looking...(read more)

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  • Daily tech links for .net and related technologies - May 13-16, 2010

    - by SanjeevAgarwal
    Daily tech links for .net and related technologies - May 13-16, 2010 Web Development Integrating Twitter Into An ASP.NET Website Using OAuth - Scott Mitchell T4MVC Extensions for MVC Partials - Evan Building a Data Grid in ASP.NET MVC - Ali Bastani Introducing the MVC Music Store - MVC 2 Sample Application and Tutorial - Jon Galloway Announcing the RTM of MvcExtensions - kazimanzurrashid Optimizing Your Website For Speed Web Design Validation with the jQuery UI Tabs Widget - Chris Love A Brief History...(read more)

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  • Daily tech links for .net and related technologies - Apr 1-3, 2010

    - by SanjeevAgarwal
    Daily tech links for .net and related technologies - Apr 1-3, 2010 Web Development Cleaner HTML Markup with ASP.NET 4 Web Forms - Client IDs - ScottGu Using jQuery and OData to Insert a Database Record - Stephen Walter Apple vs. Microsoft – A Website Usability Study Mastering ASP.NET MVC 2.0: Preview - TekPub Web Design UX Lessons Learned From Offline Experiences - Jon Phillips 5 Steps Toward jQuery Mastery - Dave Ward 20 jQuery Cheatsheets, Docs and References for Every Occasion - Paul Andrew 11...(read more)

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  • Using TPL and PLINQ to raise performance of feed aggregator

    - by DigiMortal
    In this posting I will show you how to use Task Parallel Library (TPL) and PLINQ features to boost performance of simple RSS-feed aggregator. I will use here only very basic .NET classes that almost every developer starts from when learning parallel programming. Of course, we will also measure how every optimization affects performance of feed aggregator. Feed aggregator Our feed aggregator works as follows: Load list of blogs Download RSS-feed Parse feed XML Add new posts to database Our feed aggregator is run by task scheduler after every 15 minutes by example. We will start our journey with serial implementation of feed aggregator. Second step is to use task parallelism and parallelize feeds downloading and parsing. And our last step is to use data parallelism to parallelize database operations. We will use Stopwatch class to measure how much time it takes for aggregator to download and insert all posts from all registered blogs. After every run we empty posts table in database. Serial aggregation Before doing parallel stuff let’s take a look at serial implementation of feed aggregator. All tasks happen one after other. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();           for (var index = 0; index <blogs.Count; index++)         {              ImportFeed(blogs[index]);         }     }       private void ImportFeed(BlogDto blog)     {         if(blog == null)             return;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                 }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)         {             SaveRssFeedItem(item, blog.Id, blog.CreatedById);         }     }       private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } Serial implementation of feed aggregator downloads and inserts all posts with 25.46 seconds. Task parallelism Task parallelism means that separate tasks are run in parallel. You can find out more about task parallelism from MSDN page Task Parallelism (Task Parallel Library) and Wikipedia page Task parallelism. Although finding parts of code that can run safely in parallel without synchronization issues is not easy task we are lucky this time. Feeds import and parsing is perfect candidate for parallel tasks. We can safely parallelize feeds import because importing tasks doesn’t share any resources and therefore they don’t also need any synchronization. After getting the list of blogs we iterate through the collection and start new TPL task for each blog feed aggregation. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {          var uri = new Uri(blog.RssUrl);          var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)          {              SaveRssFeedItem(item, blog.Id, blog.CreatedById);          }     }     private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } You should notice first signs of the power of TPL. We made only minor changes to our code to parallelize blog feeds aggregating. On my machine this modification gives some performance boost – time is now 17.57 seconds. Data parallelism There is one more way how to parallelize activities. Previous section introduced task or operation based parallelism, this section introduces data based parallelism. By MSDN page Data Parallelism (Task Parallel Library) data parallelism refers to scenario in which the same operation is performed concurrently on elements in a source collection or array. In our code we have independent collections we can process in parallel – imported feed entries. As checking for feed entry existence and inserting it if it is missing from database doesn’t affect other entries the imported feed entries collection is ideal candidate for parallelization. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           feed.Channel.Items.AsParallel().ForAll(a =>         {             SaveRssFeedItem(a, blog.Id, blog.CreatedById);         });      }        private void ImportAtomFeed(BlogDto blog)      {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           feed.Entries.AsParallel().ForAll(a =>         {              SaveAtomFeedEntry(a, blog.Id, blog.CreatedById);         });      } } We did small change again and as the result we parallelized checking and saving of feed items. This change was data centric as we applied same operation to all elements in collection. On my machine I got better performance again. Time is now 11.22 seconds. Results Let’s visualize our measurement results (numbers are given in seconds). As we can see then with task parallelism feed aggregation takes about 25% less time than in original case. When adding data parallelism to task parallelism our aggregation takes about 2.3 times less time than in original case. More about TPL and PLINQ Adding parallelism to your application can be very challenging task. You have to carefully find out parts of your code where you can safely go to parallel processing and even then you have to measure the effects of parallel processing to find out if parallel code performs better. If you are not careful then troubles you will face later are worse than ones you have seen before (imagine error that occurs by average only once per 10000 code runs). Parallel programming is something that is hard to ignore. Effective programs are able to use multiple cores of processors. Using TPL you can also set degree of parallelism so your application doesn’t use all computing cores and leaves one or more of them free for host system and other processes. And there are many more things in TPL that make it easier for you to start and go on with parallel programming. In next major version all .NET languages will have built-in support for parallel programming. There will be also new language constructs that support parallel programming. Currently you can download Visual Studio Async to get some idea about what is coming. Conclusion Parallel programming is very challenging but good tools offered by Visual Studio and .NET Framework make it way easier for us. In this posting we started with feed aggregator that imports feed items on serial mode. With two steps we parallelized feed importing and entries inserting gaining 2.3 times raise in performance. Although this number is specific to my test environment it shows clearly that parallel programming may raise the performance of your application significantly.

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  • Lazy Loading,Eager Loading,Explicit Loading in Entity Framework 4

    - by nikolaosk
    This is going to be the ninth post of a series of posts regarding ASP.Net and the Entity Framework and how we can use Entity Framework to access our datastore. You can find the first one here , the second one here , the third one here , the fourth one here , the fifth one here ,the sixth one here ,the seventh one here and the eighth one here . I have a post regarding ASP.Net and EntityDataSource . You can read it here .I have 3 more posts on Profiling Entity Framework applications. You can have a...(read more)

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  • Creating Property Set Expression Trees In A Developer Friendly Way

    - by Paulo Morgado
    In a previous post I showed how to create expression trees to set properties on an object. The way I did it was not very developer friendly. It involved explicitly creating the necessary expressions because the compiler won’t generate expression trees with property or field set expressions. Recently someone contacted me the help develop some kind of command pattern framework that used developer friendly lambdas to generate property set expression trees. Simply putting, given this entity class: public class Person { public string Name { get; set; } } The person in question wanted to write code like this: var et = Set((Person p) => p.Name = "me"); Where et is the expression tree that represents the property assignment. So, if we can’t do this, let’s try the next best thing that is splitting retrieving the property information from the retrieving the value to assign o the property: var et = Set((Person p) => p.Name, () => "me"); And this is something that the compiler can handle. The implementation of Set receives an expression to retrieve the property information from and another expression the retrieve the value to assign to the property: public static Expression<Action<TEntity>> Set<TEntity, TValue>( Expression<Func<TEntity, TValue>> propertyGetExpression, Expression<Func<TValue>> valueExpression) The implementation of this method gets the property information form the body of the property get expression (propertyGetExpression) and the value expression (valueExpression) to build an assign expression and builds a lambda expression using the same parameter of the property get expression as its parameter: public static Expression<Action<TEntity>> Set<TEntity, TValue>( Expression<Func<TEntity, TValue>> propertyGetExpression, Expression<Func<TValue>> valueExpression) { var entityParameterExpression = (ParameterExpression)(((MemberExpression)(propertyGetExpression.Body)).Expression); return Expression.Lambda<Action<TEntity>>( Expression.Assign(propertyGetExpression.Body, valueExpression.Body), entityParameterExpression); } And now we can use the expression to translate to another context or just compile and use it: var et = Set((Person p) => p.Name, () => name); Console.WriteLine(person.Name); // Prints: p => (p.Name = “me”) var d = et.Compile(); d(person); Console.WriteLine(person.Name); // Prints: me It can even support closures: var et = Set((Person p) => p.Name, () => name); Console.WriteLine(person.Name); // Prints: p => (p.Name = value(<>c__DisplayClass0).name) var d = et.Compile(); name = "me"; d(person); Console.WriteLine(person.Name); // Prints: me name = "you"; d(person); Console.WriteLine(person.Name); // Prints: you Not so useful in the intended scenario (but still possible) is building an expression tree that receives the value to assign to the property as a parameter: public static Expression<Action<TEntity, TValue>> Set<TEntity, TValue>(Expression<Func<TEntity, TValue>> propertyGetExpression) { var entityParameterExpression = (ParameterExpression)(((MemberExpression)(propertyGetExpression.Body)).Expression); var valueParameterExpression = Expression.Parameter(typeof(TValue)); return Expression.Lambda<Action<TEntity, TValue>>( Expression.Assign(propertyGetExpression.Body, valueParameterExpression), entityParameterExpression, valueParameterExpression); } This new expression can be used like this: var et = Set((Person p) => p.Name); Console.WriteLine(person.Name); // Prints: (p, Param_0) => (p.Name = Param_0) var d = et.Compile(); d(person, "me"); Console.WriteLine(person.Name); // Prints: me d(person, "you"); Console.WriteLine(person.Name); // Prints: you The only caveat is that we need to be able to write code to read the property in order to write to it.

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  • DB Documentation Tool

    - by Hisham El-bereky
     Recently I have uploaded new project to codeplex site, DbDocument or DbDoc project is a helper tool used side by side with MS SQL server management studio tool, you can design your DB Tables in visualized way through Diagrams and then use “DbDoc” tool to generate design document in MS Word format, the generated file can be used in design review process or as history reference, the tool facilitate and reduce the time of writing DB structure documentthe current version is not so sophisticated which is intend to generate word document in table format with all tables in DB illustrating its structure and constraints, but for now it seems to be good.   For more details check DbDoc document or go immediately to DbDoc home page http://dbdocument.codeplex.com/

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  • Reinventing the Paged IEnumerable, Weigert Style!

    - by adweigert
    I am pretty sure someone else has done this, I've seen variations as PagedList<T>, but this is my style of a paged IEnumerable collection. I just store a reference to the collection and generate the paged data when the enumerator is needed, so you could technically add to a list that I'm referencing and the properties and results would be adjusted accordingly. I don't mind reinventing the wheel when I can add some of my own personal flare ... // Extension method for easy use public static PagedEnumerable AsPaged(this IEnumerable collection, int currentPage = 1, int pageSize = 0) { Contract.Requires(collection != null); Contract.Assume(currentPage >= 1); Contract.Assume(pageSize >= 0); return new PagedEnumerable(collection, currentPage, pageSize); } public class PagedEnumerable : IEnumerable { public PagedEnumerable(IEnumerable collection, int currentPage = 1, int pageSize = 0) { Contract.Requires(collection != null); Contract.Assume(currentPage >= 1); Contract.Assume(pageSize >= 0); this.collection = collection; this.PageSize = pageSize; this.CurrentPage = currentPage; } IEnumerable collection; int currentPage; public int CurrentPage { get { if (this.currentPage > this.TotalPages) { return this.TotalPages; } return this.currentPage; } set { if (value < 1) { this.currentPage = 1; } else if (value > this.TotalPages) { this.currentPage = this.TotalPages; } else { this.currentPage = value; } } } int pageSize; public int PageSize { get { if (this.pageSize == 0) { return this.collection.Count(); } return this.pageSize; } set { this.pageSize = (value < 0) ? 0 : value; } } public int TotalPages { get { return (int)Math.Ceiling(this.collection.Count() / (double)this.PageSize); } } public IEnumerator GetEnumerator() { var pageSize = this.PageSize; var currentPage = this.CurrentPage; var startCount = (currentPage - 1) * pageSize; return this.collection.Skip(startCount).Take(pageSize).GetEnumerator(); } IEnumerator IEnumerable.GetEnumerator() { return this.GetEnumerator(); } }

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  • The WaitForAll Roadshow

    - by adweigert
    OK, so I took for granted some imaginative uses of WaitForAll but lacking that, here is how I am using. First, I have a nice little class called Parallel that allows me to spin together a list of tasks (actions) and then use WaitForAll, so here it is, WaitForAll's 15 minutes of fame ... First Parallel that allows me to spin together several Action delegates to execute, well in parallel.   public static class Parallel { public static ParallelQuery Task(Action action) { return new Action[] { action }.AsParallel(); } public static ParallelQuery> Task(Action action) { return new Action[] { action }.AsParallel(); } public static ParallelQuery Task(this ParallelQuery actions, Action action) { var list = new List(actions); list.Add(action); return list.AsParallel(); } public static ParallelQuery> Task(this ParallelQuery> actions, Action action) { var list = new List>(actions); list.Add(action); return list.AsParallel(); } }   Next, this is an example usage from an app I'm working on that just is rendering some basic computer information via WMI and performance counters. The WMI calls can be expensive given the distance and link speed of some of the computers it will be trying to communicate with. This is the actual MVC action from my controller to return the data for an individual computer.  public PartialViewResult Detail(string computerName) { var computer = this.Computers.Get(computerName); var perf = Factory.GetInstance(); var detail = new ComputerDetailViewModel() { Computer = computer }; try { var work = Parallel .Task(delegate { // Win32_ComputerSystem var key = computer.Name + "_Win32_ComputerSystem"; var system = this.Cache.Get(key); if (system == null) { using (var impersonation = computer.ImpersonateElevatedIdentity()) { system = computer.GetWmiContext().GetInstances().Single(); } this.Cache.Set(key, system); } detail.TotalMemory = system.TotalPhysicalMemory; detail.Manufacturer = system.Manufacturer; detail.Model = system.Model; detail.NumberOfProcessors = system.NumberOfProcessors; }) .Task(delegate { // Win32_OperatingSystem var key = computer.Name + "_Win32_OperatingSystem"; var os = this.Cache.Get(key); if (os == null) { using (var impersonation = computer.ImpersonateElevatedIdentity()) { os = computer.GetWmiContext().GetInstances().Single(); } this.Cache.Set(key, os); } detail.OperatingSystem = os.Caption; detail.OSVersion = os.Version; }) // Performance Counters .Task(delegate { using (var impersonation = computer.ImpersonateElevatedIdentity()) { detail.AvailableBytes = perf.GetSample(computer, "Memory", "Available Bytes"); } }) .Task(delegate { using (var impersonation = computer.ImpersonateElevatedIdentity()) { detail.TotalProcessorUtilization = perf.GetValue(computer, "Processor", "% Processor Time", "_Total"); } }).WithExecutionMode(ParallelExecutionMode.ForceParallelism); if (!work.WaitForAll(TimeSpan.FromSeconds(15), task => task())) { return PartialView("Timeout"); } } catch (Exception ex) { this.LogException(ex); return PartialView("Error.ascx"); } return PartialView(detail); }

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  • Code and Slides: Building the Account at a Glance ASP.NET MVC, EF Code First, HTML5, and jQuery Application

    - by dwahlin
    This presentation was given at the spring 2012 DevConnections conference in Las Vegas and is based on my Pluralsight course. The presentation shows how several different technologies including ASP.NET MVC, EF Code First, HTML5, jQuery, Canvas, SVG, JavaScript patterns, Ajax, and more can be integrated together to build a robust application. An example of the application in action is shown next: View more of my presentations here. The complete code (and associated SQL Server database) for the Account at a Glance application can be found here. Check out the full-length course on the topic at Pluralsight.com.

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  • PLINQ Adventure Land - WaitForAll

    - by adweigert
    PLINQ is awesome for getting a lot of work done fast, but one thing I haven't figured out yet is how to start work with PLINQ but only let it execute for a maximum amount of time and react if it is taking too long. So, as I must admit I am still learning PLINQ, I created this extension in that ignorance. It behaves similar to ForAll<> but takes a timeout and returns false if the threads don't complete in the specified amount of time. Hope this helps someone else take PLINQ further, it definitely has helped for me ...  public static bool WaitForAll<T>(this ParallelQuery<T> query, TimeSpan timeout, Action<T> action) { Contract.Requires(query != null); Contract.Requires(action != null); var exception = (Exception)null; var cts = new CancellationTokenSource(); var forAllWithCancellation = new Action(delegate { try { query.WithCancellation(cts.Token).ForAll(action); } catch (OperationCanceledException) { // NOOP } catch (AggregateException ex) { exception = ex; } }); var mrs = new ManualResetEvent(false); var callback = new AsyncCallback(delegate { mrs.Set(); }); var result = forAllWithCancellation.BeginInvoke(callback, null); if (mrs.WaitOne(timeout)) { forAllWithCancellation.EndInvoke(result); if (exception != null) { throw exception; } return true; } else { cts.Cancel(); return false; } }

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  • Identity Map Pattern and the Entity Framework

    - by nikolaosk
    This is going to be the seventh post of a series of posts regarding ASP.Net and the Entity Framework and how we can use Entity Framework to access our datastore. You can find the first one here , the second one here and the third one here , the fourth one here , the fifth one here and the sixth one here . I have a post regarding ASP.Net and EntityDataSource. You can read it here .I have 3 more posts on Profiling Entity Framework applications. You can have a look at them here , here and here . In...(read more)

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  • Is it possible to implement an infinite IEnumerable without using yield with only C# code?

    - by sinelaw
    This isn't a practical problem, it's more of a riddle. Problem I'm curious to know if there's a way to implement something equivalent to the following, but without using yield: IEnumerable<T> Infinite<T>() { while (true) { yield return default(T); } } Rules You can't use the yield keyword Use only C# itself directly - no IL code, no constructing dynamic assemblies etc. You can only use the basic .NET lib (only mscorlib.dll, System.Core.dll? not sure what else to include). However if you find a solution with some of the other .NET assemblies (WPF?!), I'm also interested. Don't implement IEnumerable or IEnumerator. Notes The closest I've come yet: IEnumerable<int> infinite = null; infinite = new int[1].SelectMany(x => new int[1].Concat(infinite)); This is "correct" but hits a StackOverflowException after 14399 iterations through the enumerable (not quite infinite). I'm thinking there might be no way to do this due to the CLR's lack of tail recursion optimization. A proof would be nice :)

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  • Visual Studio 2010 RC and Entity Framework 4 RC Support in the New Version of ADO.NET Data Providers

    Devart has recently announced the release of dotConnect products for Oracle, MySQL, PostgreSQL, and SQLite - ADO.NET providers that offer Entity Framework support, LINQ to SQL support, and contain an ORM model designer for developing LINQ to SQL and EF models based on different database engines. New dotConnect ADO.NET providers offer complete support for Visual Studio 2010 Release Candidate and Entity Framework 4 Release Candidate. Entity Developer 2.80, a designer for modeling and code generation...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Using 'new' in a projection?

    - by davenewza
    I wish to project a collection from one type (Something) to another type (SomethingElse). Yes, this is a very open-eneded question, but which of the two options below do you prefer? Creating a new instance using new: var result = query.Select(something => new SomethingElse(something)); Using a factory: var result = query.Select(something => SomethingElse.FromSomething(something)); When I think of a projection, I generally think of it as a conversion. Using new gives me this idea that I'm creating new objects during a conversion, which doesn't feel right. Semantically, SomethingElse.FromSomething() most definitely fits better. Although, the second option does require addition code to setup a factory, which could become unnecessarily compulsive.

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  • Extension methods on a null object instance – something you did not know

    - by nmarun
    Extension methods gave developers with a lot of bandwidth to do interesting (read ‘cool’) things. But there are a couple of things that we need to be aware of while using these extension methods. I have a StringUtil class that defines two extension methods: 1: public static class StringUtils 2: { 3: public static string Left( this string arg, int leftCharCount) 4: { 5: if (arg == null ) 6: { 7: throw new ArgumentNullException( "arg" ); 8: } 9: return arg.Substring(0, leftCharCount); 10...(read more)

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  • Using Subjects to Deploy Queries Dynamically

    - by Roman Schindlauer
    In the previous blog posting, we showed how to construct and deploy query fragments to a StreamInsight server, and how to re-use them later. In today’s posting we’ll integrate this pattern into a method of dynamically composing a new query with an existing one. The construct that enables this scenario in StreamInsight V2.1 is a Subject. A Subject lets me create a junction element in an existing query that I can tap into while the query is running. To set this up as an end-to-end example, let’s first define a stream simulator as our data source: var generator = myApp.DefineObservable(     (TimeSpan t) => Observable.Interval(t).Select(_ => new SourcePayload())); This ‘generator’ produces a new instance of SourcePayload with a period of t (system time) as an IObservable. SourcePayload happens to have a property of type double as its payload data. Let’s also define a sink for our example—an IObserver of double values that writes to the console: var console = myApp.DefineObserver(     (string label) => Observer.Create<double>(e => Console.WriteLine("{0}: {1}", label, e)))     .Deploy("ConsoleSink"); The observer takes a string as parameter which is used as a label on the console, so that we can distinguish the output of different sink instances. Note that we also deploy this observer, so that we can retrieve it later from the server from a different process. Remember how we defined the aggregation as an IQStreamable function in the previous article? We will use that as well: var avg = myApp     .DefineStreamable((IQStreamable<SourcePayload> s, TimeSpan w) =>         from win in s.TumblingWindow(w)         select win.Avg(e => e.Value))     .Deploy("AverageQuery"); Then we define the Subject, which acts as an observable sequence as well as an observer. Thus, we can feed a single source into the Subject and have multiple consumers—that can come and go at runtime—on the other side: var subject = myApp.CreateSubject("Subject", () => new Subject<SourcePayload>()); Subject are always deployed automatically. Their name is used to retrieve them from a (potentially) different process (see below). Note that the Subject as we defined it here doesn’t know anything about temporal streams. It is merely a sequence of SourcePayloads, without any notion of StreamInsight point events or CTIs. So in order to compose a temporal query on top of the Subject, we need to 'promote' the sequence of SourcePayloads into an IQStreamable of point events, including CTIs: var stream = subject.ToPointStreamable(     e => PointEvent.CreateInsert<SourcePayload>(e.Timestamp, e),     AdvanceTimeSettings.StrictlyIncreasingStartTime); In a later posting we will show how to use Subjects that have more awareness of time and can be used as a junction between QStreamables instead of IQbservables. Having turned the Subject into a temporal stream, we can now define the aggregate on this stream. We will use the IQStreamable entity avg that we defined above: var longAverages = avg(stream, TimeSpan.FromSeconds(5)); In order to run the query, we need to bind it to a sink, and bind the subject to the source: var standardQuery = longAverages     .Bind(console("5sec average"))     .With(generator(TimeSpan.FromMilliseconds(300)).Bind(subject)); Lastly, we start the process: standardQuery.Run("StandardProcess"); Now we have a simple query running end-to-end, producing results. What follows next is the crucial part of tapping into the Subject and adding another query that runs in parallel, using the same query definition (the “AverageQuery”) but with a different window length. We are assuming that we connected to the same StreamInsight server from a different process or even client, and thus have to retrieve the previously deployed entities through their names: // simulate the addition of a 'fast' query from a separate server connection, // by retrieving the aggregation query fragment // (instead of simply using the 'avg' object) var averageQuery = myApp     .GetStreamable<IQStreamable<SourcePayload>, TimeSpan, double>("AverageQuery"); // retrieve the input sequence as a subject var inputSequence = myApp     .GetSubject<SourcePayload, SourcePayload>("Subject"); // retrieve the registered sink var sink = myApp.GetObserver<string, double>("ConsoleSink"); // turn the sequence into a temporal stream var stream2 = inputSequence.ToPointStreamable(     e => PointEvent.CreateInsert<SourcePayload>(e.Timestamp, e),     AdvanceTimeSettings.StrictlyIncreasingStartTime); // apply the query, now with a different window length var shortAverages = averageQuery(stream2, TimeSpan.FromSeconds(1)); // bind new sink to query and run it var fastQuery = shortAverages     .Bind(sink("1sec average"))     .Run("FastProcess"); The attached solution demonstrates the sample end-to-end. Regards, The StreamInsight Team

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  • no ui or default configuration found?

    - by user51447
    I created a custom Ubuntu 11.10 amd64 desktop based distro using remastersys, but whenever I try to boot using the iso file in vmware, it shows this error : no ui or default configuration found I've tried changing the name of isolinux to syslinux but that didnt help me either! I also tried using unetbootin but it also doesnt boot, and tried every possible but to no avail. There is a similar question but it is about 10.10 and 32 bit, but that didnt solve my query and also as this is a custom distro, the solution could be different. I've also tried creating images using remastersys again and again but that wont help either. Please help me its very urgent!

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  • What is the Relative Performance of Pseudo-Class and Custom Selectors?

    - by James Wiseman
    It's my understanding that, in terms of selector speed, that #ID selectors are fastest, followed by element selectors, and then .class selectors. I have always assumed that pseudo-class selectors and custom selectors (those in the form ':selector') are similar to .class selectors, but I realised that I'm just not sure. I realise that this does depend on the complexity of the code within the pseudo-class/custom selector, so I guess I'd like to know the answer with this excluded as factor. Any help would be appreciated. Thanks.

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  • How to run a custom action after install which can run in quiet or a UI after Install (WIX)

    - by Jamie
    Hi, I basically want to able to run an command line tool that already exists on the desired machine against the directory the files were run to. I.e The Installer does the following: Specify a location for the files to go into (INSTALLOCATION variable) Then after copying has finished run a tool which will zip the files and attach them to attach them to another application. <CustomAction Id="InstallTo" Return="check" Directory="INSTALLLOCATION" Execute="immediate" ExeCommand='"C:\MyTool\Here\Tool.exe" -ad [INSTALLLOCATION] Poop 1.0'/> <InstallExecuteSequence> <Custom Action="InstallTo" After="InstallFinalize">$InstallTo&gt;2</Custom> </InstallExecuteSequence> At the moment I'm not sure anyuthing is being called, is there a way to basically have this two step install and report progress if the tool failed/doesn't exist etc. Thanks, Jamie

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  • Passing integer lists in a sql query, best practices

    - by Artiom Chilaru
    I'm currently looking at ways to pass lists of integers in a SQL query, and try to decide which of them is best in which situation, what are the benefots of each, and what are the pitfalls, what should be avoided :) Right now I know of 3 ways that we currently use in our application. 1) Table valued parameter: Create a new Table Valued Parameter in sql server: CREATE TYPE [dbo].[TVP_INT] AS TABLE( [ID] [int] NOT NULL ) Then run the query against it: using (var conn = new SqlConnection(DataContext.GetDefaultConnectionString)) { var comm = conn.CreateCommand(); comm.CommandType = CommandType.Text; comm.CommandText = @" UPDATE DA SET [tsLastImportAttempt] = CURRENT_TIMESTAMP FROM [Account] DA JOIN @values IDs ON DA.ID = IDs.ID"; comm.Parameters.Add(new SqlParameter("values", downloadResults.Select(d => d.ID).ToDataTable()) { TypeName = "TVP_INT" }); conn.Open(); comm.ExecuteScalar(); } The major disadvantages of this method is the fact that Linq doesn't support table valued params (if you create an SP with a TVP param, linq won't be able to run it) :( 2) Convert the list to Binary and use it in Linq! This is a bit better.. Create an SP, and you can run it within linq :) To do this, the SP will have an IMAGE parameter, and we'll be using a user defined function (udf) to convert this to a table.. We currently have implementations of this function written in C++ and in assembly, both have pretty much the same performance :) Basically, each integer is represented by 4 bytes, and passed to the SP. In .NET we have an extension method that convers an IEnumerable to a byte array The extension method: public static Byte[] ToBinary(this IEnumerable intList) { return ToBinaryEnum(intList).ToArray(); } private static IEnumerable<Byte> ToBinaryEnum(IEnumerable<Int32> intList) { IEnumerator<Int32> marker = intList.GetEnumerator(); while (marker.MoveNext()) { Byte[] result = BitConverter.GetBytes(marker.Current); Array.Reverse(result); foreach (byte b in result) yield return b; } } The SP: CREATE PROCEDURE [Accounts-UpdateImportAttempts] @values IMAGE AS BEGIN UPDATE DA SET [tsLastImportAttempt] = CURRENT_TIMESTAMP FROM [Account] DA JOIN dbo.udfIntegerArray(@values, 4) IDs ON DA.ID = IDs.Value4 END And we can use it by running the SP directly, or in any linq query we need using (var db = new DataContext()) { db.Accounts_UpdateImportAttempts(downloadResults.Select(d => d.ID).ToBinary()); // or var accounts = db.Accounts .Where(a => db.udfIntegerArray(downloadResults.Select(d => d.ID).ToBinary(), 4) .Select(i => i.Value4) .Contains(a.ID)); } This method has the benefit of using compiled queries in linq (which will have the same sql definition, and query plan, so will also be cached), and can be used in SPs as well. Both these methods are theoretically unlimited, so you can pass millions of ints at a time :) 3) The simple linq .Contains() It's a more simple approach, and is perfect in simple scenarios. But is of course limited by this. using (var db = new DataContext()) { var accounts = db.Accounts .Where(a => downloadResults.Select(d => d.ID).Contains(a.ID)); } The biggest drawback of this method is that each integer in the downloadResults variable will be passed as a separate int.. In this case, the query is limited by sql (max allowed parameters in a sql query, which is a couple of thousand, if I remember right). So I'd like to ask.. What do you think is the best of these, and what other methods and approaches have I missed?

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  • Dynamic Data with Subsonic 3

    - by Ezequiel Bertti
    i want to make a webproject with Subsonic and Dynamic Data... But when i go register the ContextData a don't have it in subsonic with LINQ... in Global.asax.cs a have to do something like this model.RegisterContext(SubSonicRepo, new ContextConfiguration() { ScaffoldAllTables = true }); how can i make it work? have some way to make it work? using entities or LINQ everything work... but using Subsonic with linq it not work...

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  • Why should I prepend my custom attributes with "data-"?

    - by Horace Loeb
    So any custom data attribute that I use should start with "data-": <li class="user" data-name="John Resig" data-city="Boston" data-lang="js" data-food="Bacon"> <b>John says:</b> <span>Hello, how are you?</span> </li> Will anything bad happen if I just ignore this? I.e.: <li class="user" name="John Resig" city="Boston" lang="js" food="Bacon"> <b>John says:</b> <span>Hello, how are you?</span> </li> I guess one bad thing is that my custom attributes could conflict with HTML attributes with special meanings (e.g., name), but aside from this, is there a problem with just writing "example_text" instead of "data-example_text"? (It won't validate, but who cares?)

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  • Unable to use Client Application Services with custom MembershipProvider.

    - by Shimmy
    Hi, I have a Windows-Forms Application that I configured to use with an ASP.NET Service that is an Authentication service using a custom MembershipProvider. When I call Membership.CreateUser in the Windows Application a NotSupportedException is thrown telling: "Specified method is not supported.". I tried creating a web page in the website and test the MembershipProvider, everything works just fine when woeking from within the website. Any ideas or link for how to use custom (not SqlMembershipProvider) MembershipProvider will be really appreciated! Edit: The method ValidateUser does work. The overriden CreateUser doesn't work I tried Override Sub CreateUser(.......) As MembershipUser Return New User() End Sub But I still get the same excetption as before.

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