asp net web api - Page 62

Any audio hosting/uploading API ?

- by Emily

Hello. Is there any REST API to upload & host mp3 and audio files and get a direct link like IMGUR API for images? Thanks

Where would async calls make sense in an ASP.net (MVC) Web Application?

I'm just wondering, if I have an ASP.net Web Application, either WebForms or MVC, is there any situation where doing stuff asynchronously would make sense? The Web Server already handles threading for me in that it spins up multiple threads to handle requests, and most request processing is rather simple and straight forward. I see some use for when stuff truly is a) expensive and b) can be parallelized. but these are the minority cases (at least from what I've encountered). Is there any gain from async in the simple "Read some input, do some CRUD, display some output" scenario?

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Google Maps API DirectionsRendererOptions not working?

- by YWE

I am trying to use DirectionsRenderer to display a DirectionsResult without the route list. According to the API version 3 documentation, there is a "hideRouteList" property of the DirectionsRendererOptions object that when set to true should hide the route list. I cannot get it to work. Is this a bug or am I just not coding this correctly? Following is my code. <html> <head> <title>Driving Directions</title> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"> </script> <script type="text/javascript">  </script> </head> <body onLoad="initialize();"> <div id="dir-container"></div> </body> </html>

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.NET Regex: Howto extract IPv6 address parts

- by Quandary

Question: How does the .NET regex string to extract IPv6 addresses look like ? I can get it to extract a simple IPv6 address like "1050:0:0:0:5:600:300c:326b" but not the colon format ("ff06::c3"); My problem is, it should extract a 0 for every omitted value between the :: How do I do that? Below my code + description. Specify IPv6 addresses by omitting leading zeros. For example, IPv6 address 1050:0000:0000:0000:0005:0600:300c:326b may be written as 1050:0:0:0:5:600:300c:326b. Double colon Specify IPv6 addresses by using double colons (::) in place of a series of zeros. For example, IPv6 address ff06:0:0:0:0:0:0:c3 may be written as ff06::c3. Double colons may be used only once in an IP address. strInputString = "ff06::c3"; strInputString = "1050:0000:0000:0000:0005:0600:300c:326b"; string strPattern = "([A-Fa-f0-9]{1,4}:){7}([A-Fa-f0-9]{1,4})"; //strPattern = @"\A(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}\z"; //strPattern = @"(\A([0-9a-f]{1,4}:){1,1}(:[0-9a-f]{1,4}){1,6}\Z)|(\A([0-9a-f]{1,4}:){1,2}(:[0-9a-f]{1,4}){1,5}\Z)|(\A([0-9a-f]{1,4}:){1,3}(:[0-9a-f]{1,4}){1,4}\Z)|(\A([0-9a-f]{1,4}:){1,4}(:[0-9a-f]{1,4}){1,3}\Z)|(\A([0-9a-f]{1,4}:){1,5}(:[0-9a-f]{1,4}){1,2}\Z)|(\A([0-9a-f]{1,4}:){1,6}(:[0-9a-f]{1,4}){1,1}\Z)|(\A(([0-9a-f]{1,4}:){1,7}|:):\Z)|(\A:(:[0-9a-f]{1,4}){1,7}\Z)|(\A((([0-9a-f]{1,4}:){6})(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3})\Z)|(\A(([0-9a-f]{1,4}:){5}[0-9a-f]{1,4}:(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3})\Z)|(\A([0-9a-f]{1,4}:){5}:[0-9a-f]{1,4}:(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z)|(\A([0-9a-f]{1,4}:){1,1}(:[0-9a-f]{1,4}){1,4}:(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z)|(\A([0-9a-f]{1,4}:){1,2}(:[0-9a-f]{1,4}){1,3}:(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z)|(\A([0-9a-f]{1,4}:){1,3}(:[0-9a-f]{1,4}){1,2}:(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z)|(\A([0-9a-f]{1,4}:){1,4}(:[0-9a-f]{1,4}){1,1}:(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z)|(\A(([0-9a-f]{1,4}:){1,5}|:):(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z)|(\A:(:[0-9a-f]{1,4}){1,5}:(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\Z) "; //strPattern = @"/^\s*((([0-9A-Fa-f]{1,4}:){7}([0-9A-Fa-f]{1,4}|:))|(([0-9A-Fa-f]{1,4}:){6}(:[0-9A-Fa-f]{1,4}|((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){5}(((:[0-9A-Fa-f]{1,4}){1,2})|:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3})|:))|(([0-9A-Fa-f]{1,4}:){4}(((:[0-9A-Fa-f]{1,4}){1,3})|((:[0-9A-Fa-f]{1,4})?:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){3}(((:[0-9A-Fa-f]{1,4}){1,4})|((:[0-9A-Fa-f]{1,4}){0,2}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){2}(((:[0-9A-Fa-f]{1,4}){1,5})|((:[0-9A-Fa-f]{1,4}){0,3}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(([0-9A-Fa-f]{1,4}:){1}(((:[0-9A-Fa-f]{1,4}){1,6})|((:[0-9A-Fa-f]{1,4}){0,4}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:))|(:(((:[0-9A-Fa-f]{1,4}){1,7})|((:[0-9A-Fa-f]{1,4}){0,5}:((25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}))|:)))(%.+)?\s*$/"; //strPattern = @"(:?[0-9a-fA-F]{1,4}:){7}([0-9a-fA-F]{1,4})\z"; //strPattern = @"\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)\z"; //strPattern = @"\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}:)*)(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\z"; //strPattern = @"/^(?:(?:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9](?::|$)){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))$/i"; System.Text.RegularExpressions.Regex reValidationRule = new System.Text.RegularExpressions.Regex("^" + strPattern + "$"); if (reValidationRule.Match(strInputString).Success) // If matching pattern { System.Text.RegularExpressions.Match maResult = System.Text.RegularExpressions.Regex.Match(strInputString, strPattern); // Console.WriteLine(maResult.Groups.Count) string[] astrReturnValues = new string[4]; System.Text.RegularExpressions.GroupCollection gc = maResult.Groups; System.Text.RegularExpressions.CaptureCollection cc; int counter; //System.Web.Script.Serialization.JavaScriptSerializer jssJSONserializer = new System.Web.Script.Serialization.JavaScriptSerializer(); //Console.WriteLine(jssJSONserializer.Serialize()); // Loop through each group. for (int i = 0; i < gc.Count; i++) { Console.WriteLine("Group: {0}", i); cc = gc[i].Captures; counter = cc.Count; // Print number of captures in this group. Console.WriteLine("Captures count = " + counter.ToString()); // Loop through each capture in group. for (int ii = 0; ii < counter; ii++) { Console.WriteLine("Capture: {0}", ii); // Print capture and position. Console.WriteLine(cc[ii] + " Starts at character " + cc[ii].Index); } }

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ASP.NET AJAX and my axe!

- by Marlon

So, I'm seriously considering axing ASP.NET AJAX from my future projects as I honestly feel it's too bloated, and at times convoluted. I'm also starting to feel it is a dying library in the .NET framework as I hardly see any quality components from the open-source community. All the kick-ass components are usually equally bloated commercial components... It was cool at first, but now I tend to get annoyed with it more than anything else. I'm planning on switching over to the jQuery library as just about everything in ASP.NET AJAX is often easily achievable with jQuery, and, more often than not, more graceful of a solution that ASP.NET AJAX and it has a much stronger open-source community. Perhaps, it's just me, but do you feel the same way about ASP.NET AJAX? How was/is your experience working with ASP.NET AJAX?

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A plan to study ASP.NET + C# + SQL + SQL Server [closed]

- by ali saleem

Possible Duplicates: Should I be a professional in C# programming in order to build good web applications using ASP.NET? Is there a combination of language and database that is both great to use and free/cheap? C# for web development? or C# as general purpose programming? ASP.NET MVC book for absolute beginners Will it cost me a lot if I chose ASP.NET and IIS? Is it possible to use MySQL in ASP.NET? Best books to start with ASP.NET MVC / C# and Visual Studio Is it enough for me to learn the above technologies to become a professional web developer? If so then how can I learn them? together or to start with C# for example at first? If there is another thing I should learn please tell me about it.

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Best books to start with ASP.NET MVC / C# and Visual Studio [closed]

- by Goma

Possible Duplicate: ASP.NET MVC book for absolute beginners Hi guys, finally I have made a decision to go with ASP.NET and C# and I hope I have made the right decision. I would like to ask you, the experts in ASP.NET and C#, could you please tell me where should I start learning and will you recommened me learn ASP.NET or ASP.NET MVC? And what about C#, what is the best book for beginners to learn C#? And by the way, how should I start with SQL Server and SQL,etc? Should I pick up a special book or will I learn it with C#? Cheers.

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Newbie in ASP.Net

- by dnvThai

I am learning ASP.Net and I am confusing between ASP.Net WebPages, ASP.Net WebForms and ASP.Net MVC. I have read a lot of articles and known the simple difference of their functions, but I don't know the differences of their code. E.g: When I look at int* p = new int(); ... I know that it's C++ style. and Dim A as String it have to be Visual Basic. [?1] I'm not able to detect like that in ASP.Net. How do they different in codes? I use Visual Studio 2010 Express Edition.I like to use C# (I also was learned VisualBasic in shool, but I don't like him). When I create a new project, there're too many types of project, then, I don't know which I should choose (I just want to make a simple site). [?2] What are they used to? Thanks

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Combining a content management system with ASP.NET

- by Ek0nomik

I am going to be creating a site that seems like it requires a blend of a content management system (CMS) and some custom web development (which is done in ASP.NET MVC). I have plenty of web development experience to understand the ASP.NET MVC side of the fence, but, I don't have a lot of CMS knowledge aside from getting one stood up. Right now my biggest question is around integrating security from ASP.NET with the CMS. I currently have an ASP.NET MVC site that handles the authentication for multiple production sites and creates an authentication cookie under our domain (*.example.com). The page acts like a single sign on page since the cookie is a wildcard and can be used in any other applications of the same domain. I'd really like to avoid having users put in their credentials twice. Is there a CMS that will play well with the ASP.NET Forms Authentication given how I have these existing applications structured? As an aside, right now I am leaning towards Drupal, but, that isn't finalized.

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ASP.NET/.NET: Method to determine whether string is or contains HTML entity

- by ChrisIsTheBomb

Is there a method anywhere in the .NET framework or System.Web that will tell me whether a string contains an HTML or is one? Should I just Server.HtmlEncode(myString) and see if its length is longer than myString's length before encoding?

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ASP.NET WebForms vs MVC [after VS2010/.NET 4.0 announcement]

- by fjxx

Two of the biggest advantages of MVC over webforms were non-existent viewstate and URL routing. VS2010 and .NET 4.0 incorporates built-in URL routing for Webforms as well as better control for viewstate. I advocate use of MVC for extranet sites due to the MVC design pattern and its general lightweight nature but in light of this new announcement has Webforms closed the gap? Why would you still pick MVC over Webforms? Thanks

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Returning date from Stored procedure in ASP.Net/VB.Net

- by Mo

Hi, I want to execute a method on VB.Net to return a date which is in the stored procedure. I tried using ExecuteScalar but it doesnt work it retruns error 'Implicit conversion from data type datetime to int is not allowed. Use the CONVERT function to run this query' Any help would be much appreciated please? thank you below is the code Public Function GetHolidaydate(ByVal struserID as String) As DateTime Dim objArgs1 As New clsSQLStoredProcedureParams objArgs1.Add("@userID", Me.Tag) objArgs1.Add("@Date", 0, 0, ParameterDirection.Output) Return (CDate(ExecuteScalar(clsLibrary.MyStoredProcedure.GetHolidayDate, objArgs1))) End Function

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Parallelism in .NET – Part 19, TaskContinuationOptions

- by Reed

My introduction to Task continuations demonstrates continuations on the Task class. In addition, I’ve shown how continuations allow handling of multiple tasks in a clean, concise manner. Continuations can also be used to handle exceptional situations using a clean, simple syntax. In addition to standard Task continuations , the Task class provides some options for filtering continuations automatically. This is handled via the TaskContinationOptions enumeration, which provides hints to the TaskScheduler that it should only continue based on the operation of the antecedent task. This is especially useful when dealing with exceptions. For example, we can extend the sample from our earlier continuation discussion to include support for handling exceptions thrown by the Factorize method: // Get a copy of the UI-thread task scheduler up front to use later var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // Start our task var factorize = Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }); // When we succeed, report the results to the UI factorize.ContinueWith(task => textBox1.Text = string.Format("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result), CancellationToken.None, TaskContinuationOptions.NotOnFaulted, uiScheduler); // When we have an exception, report it factorize.ContinueWith(task => textBox1.Text = string.Format("Error: {0}", task.Exception.Message), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, uiScheduler); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above code works by using a combination of features. First, we schedule our task, the same way as in the previous example. However, in this case, we use a different overload of Task.ContinueWith which allows us to specify both a specific TaskScheduler (in order to have your continuation run on the UI’s synchronization context) as well as a TaskContinuationOption. In the first continuation, we tell the continuation that we only want it to run when there was not an exception by specifying TaskContinuationOptions.NotOnFaulted. When our factorize task completes successfully, this continuation will automatically run on the UI thread, and provide the appropriate feedback. However, if the factorize task has an exception – for example, if the Factorize method throws an exception due to an improper input value, the second continuation will run. This occurs due to the specification of TaskContinuationOptions.OnlyOnFaulted in the options. In this case, we’ll report the error received to the user. We can use TaskContinuationOptions to filter our continuations by whether or not an exception occurred and whether or not a task was cancelled. This allows us to handle many situations, and is especially useful when trying to maintain a valid application state without ever blocking the user interface. The same concepts can be extended even further, and allow you to chain together many tasks based on the success of the previous ones. Continuations can even be used to create a state machine with full error handling, all without blocking the user interface thread.

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Creating an HttpHandler to handle request of your own extension

- by Jalpesh P. Vadgama

I have already posted about http handler in details before some time here. Now let’s create an http handler which will handle my custom extension. For that we need to create a http handlers class which will implement Ihttphandler. As we are implementing IHttpHandler we need to implement one method called process request and another one is isReusable property. The process request function will handle all the request of my custom extension. so Here is the code for my http handler class. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; namespace Experiement { public class MyExtensionHandler:IHttpHandler { public MyExtensionHandler() { //Implement intialization here } bool IHttpHandler.IsReusable { get { return true; } } void IHttpHandler.ProcessRequest(HttpContext context) { string excuttablepath = context.Request.AppRelativeCurrentExecutionFilePath; if (excuttablepath.Contains("HelloWorld.dotnetjalps")) { Page page = new HelloWorld(); page.AppRelativeVirtualPath = context.Request.AppRelativeCurrentExecutionFilePath; page.ProcessRequest(context); } } } } Here in above code you can see that in process request function I am getting current executable path and then I am processing that page. Now Lets create a page with extension .dotnetjalps and then we will process this page with above created http handler. so let’s create it. It will create a page like following. Now let’s write some thing in page load Event like following. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; namespace Experiement { public partial class HelloWorld : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Response.Write("Hello World"); } } } Now we have to tell our web server that we want to process request from this .dotnetjalps extension through our custom http handler for that we need to add a tag in httphandler sections of web.config like following. <configuration> <system.web> <compilation debug="true" targetFramework="4.0" /> <httpHandlers> <add verb="*" path="*.dotnetjalps" type="Experiement.MyExtensionHandler,Experiement"/> </httpHandlers> </system.web> </configuration> That’s it now run that page into browser and it will execute like following in browser That’s you.. Isn’t it cool.. Stay tuned for more.. Happy programming.. Technorati Tags: HttpHandler,ASP.NET,Extension

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WSDL-world vs CLR-world – some differences

- by nmarun

A change in mindset is required when switching between a typical CLR application and a web service application. There are some things in a CLR environment that just don’t add-up in a WSDL arena (and vice-versa). I’m listing some of them here. When I say WSDL-world, I’m mostly talking with respect to a WCF Service and / or a Web Service. No (direct) Method Overloading: You definitely can have overloaded methods in a, say, Console application, but when it comes to a WCF / Web Services application, you need to adorn these overloaded methods with a special attribute so the service knows which specific method to invoke. When you’re working with WCF, use the Name property of the OperationContract attribute to provide unique names. 1: [OperationContract(Name = "AddInt")] 2: int Add(int arg1, int arg2); 3: 4: [OperationContract(Name = "AddDouble")] 5: double Add(double arg1, double arg2); By default, the proxy generates the code for this as: 1: [System.ServiceModel.OperationContractAttribute( 2: Action="http://tempuri.org/ILearnWcfService/AddInt", 3: ReplyAction="http://tempuri.org/ILearnWcfService/AddIntResponse")] 4: int AddInt(int arg1, int arg2); 5: 6: [System.ServiceModel.OperationContractAttribute( 7: Action="http://tempuri.org/ILearnWcfServiceExtend/AddDouble", 8: ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/AddDoubleResponse")] 9: double AddDouble(double arg1, double arg2); With Web Services though the story is slightly different. Even after setting the MessageName property of the WebMethod attribute, the proxy does not change the name of the method, but only the underlying soap message changes. 1: [WebMethod] 2: public string HelloGalaxy() 3: { 4: return "Hello Milky Way!"; 5: } 6: 7: [WebMethod(MessageName = "HelloAnyGalaxy")] 8: public string HelloGalaxy(string galaxyName) 9: { 10: return string.Format("Hello {0}!", galaxyName); 11: } The one thing you need to remember is to set the WebServiceBinding accordingly. 1: [WebServiceBinding(ConformsTo = WsiProfiles.None)] The proxy is: 1: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloGalaxy", 2: RequestNamespace="http://tempuri.org/", 3: ResponseNamespace="http://tempuri.org/", 4: Use=System.Web.Services.Description.SoapBindingUse.Literal, 5: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 6: public string HelloGalaxy() 7: 8: [System.Web.Services.WebMethodAttribute(MessageName="HelloGalaxy1")] 9: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloAnyGalaxy", 10: RequestElementName="HelloAnyGalaxy", 11: RequestNamespace="http://tempuri.org/", 12: ResponseElementName="HelloAnyGalaxyResponse", 13: ResponseNamespace="http://tempuri.org/", 14: Use=System.Web.Services.Description.SoapBindingUse.Literal, 15: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 16: [return: System.Xml.Serialization.XmlElementAttribute("HelloAnyGalaxyResult")] 17: public string HelloGalaxy(string galaxyName) 18: You see the calling method name is the same in the proxy, however the soap message that gets generated is different. Using interchangeable data types: See details on this here. Type visibility: In a CLR-based application, if you mark a field as private, well we all know, it’s ‘private’. Coming to a WSDL side of things, in a Web Service, private fields and web methods will not get generated in the proxy. In WCF however, all your operation contracts will be public as they get implemented from an interface. Even in case your ServiceContract interface is declared internal/private, you will see it as a public interface in the proxy. This is because type visibility is a CLR concept and has no bearing on WCF. Also if a private field has the [DataMember] attribute in a data contract, it will get emitted in the proxy class as a public property for the very same reason. 1: [DataContract] 2: public struct Person 3: { 4: [DataMember] 5: private int _x; 6: 7: [DataMember] 8: public int Id { get; set; } 9: 10: [DataMember] 11: public string FirstName { get; set; } 12: 13: [DataMember] 14: public string Header { get; set; } 15: } 16: } See the ‘_x’ field is a private member with the [DataMember] attribute, but the proxy class shows as below: 1: [System.Runtime.Serialization.DataMemberAttribute()] 2: public int _x { 3: get { 4: return this._xField; 5: } 6: set { 7: if ((this._xField.Equals(value) != true)) { 8: this._xField = value; 9: this.RaisePropertyChanged("_x"); 10: } 11: } 12: } Passing derived types to web methods / operation contracts: Once again, in a CLR application, I can have a derived class be passed as a parameter where a base class is expected. I have the following set up for my WCF service. 1: [DataContract] 2: public class Employee 3: { 4: [DataMember(Name = "Id")] 5: public int EmployeeId { get; set; } 6: 7: [DataMember(Name="FirstName")] 8: public string FName { get; set; } 9: 10: [DataMember] 11: public string Header { get; set; } 12: } 13: 14: [DataContract] 15: public class Manager : Employee 16: { 17: [DataMember] 18: private int _x; 19: } 20: 21: // service contract 22: [OperationContract] 23: Manager SaveManager(Employee employee); 24: 25: // in my calling code 26: Manager manager = new Manager {_x = 1, FirstName = "abc"}; 27: manager = LearnWcfServiceClient.SaveManager(manager); The above will throw an exception saying: In short, this is saying, that a Manager type was found where an Employee type was expected! Hierarchy flattening of interfaces in WCF: See details on this here. In CLR world, you’ll see the entire hierarchy as is. That’s another difference. Using ref parameters: * can use ref for parameters, but operation contract should not be one-way (gives an error when you do an update service reference) => bad programming; create a return object that is composed of everything you need! This one kind of stumped me. Not sure why I tried this, but you can pass parameters prefixed with ref keyword* (* terms and conditions apply). The main issue is this, how would we know the changes that were made to a ‘ref’ input parameter are returned back from the service and updated to the local variable? Turns out both Web Services and WCF make this tracking happen by passing the input parameter in the response soap. This way when the deserializer does its magic, it maps all the elements of the response xml thereby updating our local variable. Here’s what I’m talking about. 1: [WebMethod(MessageName = "HelloAnyGalaxy")] 2: public string HelloGalaxy(ref string galaxyName) 3: { 4: string output = string.Format("Hello {0}", galaxyName); 5: if (galaxyName == "Andromeda") 6: { 7: galaxyName = string.Format("{0} (2.5 million light-years away)", galaxyName); 8: } 9: return output; 10: } This is how the request and response look like in soapUI. As I said above, the behavior is quite similar for WCF as well. But the catch comes when you have a one-way web methods / operation contracts. If you have an operation contract whose return type is void, is marked one-way and that has ref parameters then you’ll get an error message when you try to reference such a service. 1: [OperationContract(Name = "Sum", IsOneWay = true)] 2: void Sum(ref double arg1, ref double arg2); 3: 4: public void Sum(ref double arg1, ref double arg2) 5: { 6: arg1 += arg2; 7: } This is what I got when I did an update to my service reference: Makes sense, because a OneWay operation is… one-way – there’s no returning from this operation. You can also have a one-way web method: 1: [SoapDocumentMethod(OneWay = true)] 2: [WebMethod(MessageName = "HelloAnyGalaxy")] 3: public void HelloGalaxy(ref string galaxyName) This will throw an exception message similar to the one above when you try to update your web service reference. In the CLR space, there’s no such concept of a ‘one-way’ street! Yes, there’s void, but you very well can have ref parameters returned through such a method. Just a point here; although the ref/out concept sounds cool, it’s generally is a code-smell. The better approach is to always return an object that is composed of everything you need returned from a method. These are some of the differences that we need to bear when dealing with services that are different from our daily ‘CLR’ life.

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How to best integrate HTML/design with C# code in ASP.Net or ASP.Net MVC?

- by LuftMensch

We're working on a new ASP.Net site. The last major site we did was in classic ASP--the procedure we used there was to have the HTML completed first, then "bring it to life" with the ASP code. In the ASP.Net world, how does this work? I.e. how do the designers do their work if much of the mark-up is actually being generated by the server controls? We are also looking at ASP.Net MVC as a potential lightweight alternative. Would be very interested to know what was worked best for people in both scenarios in terms of working with the designers and integrating their work with the code.

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ASP.NET - ViewState: empty placeholder generates view state

- by Budda

On my web-page I have PlaceHolder, not controls are loaded into it. <asp:PlaceHolder ID="PlaceHolderStatMain" runat="server"> </asp:PlaceHolder> I am looking the ViewState generated for the page, it is the following: <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUJLTg1NDkyNTUzD2QWAgIDD2QWAgIND2QWAmYPZBYCAgEPZBYCZg9kFgJmD2QWBmYPFQEYL3N0YXRfc3RhZGl1bS9sZWFndWVfV0VGZAIBDxUBGC9zdGF0X3N0YWRpdW0vbGVhZ3VlX0VFRmQCAg8VARgvc3RhdF9zdGFkaXVtL2xlYWd1ZV9GQ1VkZEuSBUr5LFL6WfCehNBJgjrq0GzwWCWN2qlU70V7LAAb" /> When I set EnableViewState to false: <asp:PlaceHolder ID="PlaceHolderStatMain" runat="server" EnableViewState="false"> </asp:PlaceHolder> The viewstate content was decreased significantly: <input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUJLTg1NDkyNTUzZGTTn8Y28VwmpE/K7yPPkLFvhrqMdU8THijFW/BMFzk0tQ==" /> Question: how to remove 'useless' viewstate content without disabling viewstate for placeholder himself (I would like other control loaded into placeholder to has viewstate)? Is it possible at all? Any thought are welcome! P.S. I am using ASP.NET 4.0

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how to set previously selected radio button checked in classic asp after page is postbacked

- by Nikhil Vaghela

I have never worked on classic ASP and unfortunately i am supposed to modify an old classisc ASP web site. ASP.Net ViewState does take care of maintaining control's sate automatically. How do i do it in classic ASP ? I have two radio buttons and a text box placed on my ASP page, when user types in something in the text box based on radio button selection we display different search results. Now what i need is to keep the previously selected radio button as checked after the page is postbacked. How do i do that ?

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Monitoring .NET ASP.NET Applications

- by James Hollingworth

I have a number of applications running on top of ASP.NET I want to monitor. The main things I care about are: Exceptions: We currently some custom code which will email us when an exception occurs. If the application is failing hard it will crash our outlook... I know (and use) elmah which partly solves the problem however it is still just a big table of exceptions with a pretty(ish) UI. I want something that makes sense of all of these exceptions (e.g. groups exceptions, alerts when new ones occur, tells me what the common ones are that I should fix, etc) Logging: We currently log to files which are then accessible via a shared folder which dev's grep & tail. Does anyone know of better ways of presenting this information. In an ideal world I want to associate it with exceptions. Performance: Request times, memory usage, cpu, etc. whatever stats I can get I'm guessing this is probably going to be solved by a number of tools, has anyone got any suggestions?

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Parallelism in .NET – Part 16, Creating Tasks via a TaskFactory

- by Reed

The Task class in the Task Parallel Library supplies a large set of features. However, when creating the task, and assigning it to a TaskScheduler, and starting the Task, there are quite a few steps involved. This gets even more cumbersome when multiple tasks are involved. Each task must be constructed, duplicating any options required, then started individually, potentially on a specific scheduler. At first glance, this makes the new Task class seem like more work than ThreadPool.QueueUserWorkItem in .NET 3.5. In order to simplify this process, and make Tasks simple to use in simple cases, without sacrificing their power and flexibility, the Task Parallel Library added a new class: TaskFactory. The TaskFactory class is intended to “Provide support for creating and scheduling Task objects.” Its entire purpose is to simplify development when working with Task instances. The Task class provides access to the default TaskFactory via the Task.Factory static property. By default, TaskFactory uses the default TaskScheduler to schedule tasks on a ThreadPool thread. By using Task.Factory, we can automatically create and start a task in a single “fire and forget” manner, similar to how we did with ThreadPool.QueueUserWorkItem: Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This provides us with the same level of simplicity we had with ThreadPool.QueueUserWorkItem, but even more power. For example, we can now easily wait on the task: // Start our task on a background thread var task = Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); // Do other work on the main thread, // while the task above executes in the background this.ExecuteWorkSynchronously(); // Wait for the background task to finish task.Wait(); TaskFactory simplifies creation and startup of simple background tasks dramatically. In addition to using the default TaskFactory, it’s often useful to construct a custom TaskFactory. The TaskFactory class includes an entire set of constructors which allow you to specify the default configuration for every Task instance created by that factory. This is particularly useful when using a custom TaskScheduler. For example, look at the sample code for starting a task on the UI thread in Part 15: // Given the following, constructed on the UI thread // TaskScheduler uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // When inside a background task, we can do string status = GetUpdatedStatus(); (new Task(() => { statusLabel.Text = status; })) .Start(uiScheduler); This is actually quite a bit more complicated than necessary. When we create the uiScheduler instance, we can use that to construct a TaskFactory that will automatically schedule tasks on the UI thread. To do that, we’d create the following on our main thread, prior to constructing our background tasks: // Construct a task scheduler from the current SynchronizationContext (UI thread) var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // Construct a new TaskFactory using our UI scheduler var uiTaskFactory = new TaskFactory(uiScheduler); If we do this, when we’re on a background thread, we can use this new TaskFactory to marshal a Task back onto the UI thread. Our previous code simplifies to: // When inside a background task, we can do string status = GetUpdatedStatus(); // Update our UI uiTaskFactory.StartNew( () => statusLabel.Text = status); Notice how much simpler this becomes! By taking advantage of the convenience provided by a custom TaskFactory, we can now marshal to set data on the UI thread in a single, clear line of code!

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MvcExtensions – Bootstrapping

- by kazimanzurrashid

When you create a new ASP.NET MVC application you will find that the global.asax contains the following lines: namespace MvcApplication1 { // Note: For instructions on enabling IIS6 or IIS7 classic mode, // visit http://go.microsoft.com/?LinkId=9394801 public class MvcApplication : System.Web.HttpApplication { public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults ); } protected void Application_Start() { AreaRegistration.RegisterAllAreas(); RegisterRoutes(RouteTable.Routes); } } } As the application grows, there are quite a lot of plumbing code gets into the global.asax which quickly becomes a design smell. Lets take a quick look at the code of one of the open source project that I recently visited: public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute("Default","{controller}/{action}/{id}", new { controller = "Home", action = "Index", id = "" }); } protected override void OnApplicationStarted() { Error += OnError; EndRequest += OnEndRequest; var settings = new SparkSettings() .AddNamespace("System") .AddNamespace("System.Collections.Generic") .AddNamespace("System.Web.Mvc") .AddNamespace("System.Web.Mvc.Html") .AddNamespace("MvcContrib.FluentHtml") .AddNamespace("********") .AddNamespace("********.Web") .SetPageBaseType("ApplicationViewPage") .SetAutomaticEncoding(true); #if DEBUG settings.SetDebug(true); #endif var viewFactory = new SparkViewFactory(settings); ViewEngines.Engines.Add(viewFactory); #if !DEBUG PrecompileViews(viewFactory); #endif RegisterAllControllersIn("********.Web"); log4net.Config.XmlConfigurator.Configure(); RegisterRoutes(RouteTable.Routes); Factory.Load(new Components.WebDependencies()); ModelBinders.Binders.DefaultBinder = new Binders.GenericBinderResolver(Factory.TryGet<IModelBinder>); ValidatorConfiguration.Initialize("********"); HtmlValidationExtensions.Initialize(ValidatorConfiguration.Rules); } private void OnEndRequest(object sender, System.EventArgs e) { if (((HttpApplication)sender).Context.Handler is MvcHandler) { CreateKernel().Get<ISessionSource>().Close(); } } private void OnError(object sender, System.EventArgs e) { CreateKernel().Get<ISessionSource>().Close(); } protected override IKernel CreateKernel() { return Factory.Kernel; } private static void PrecompileViews(SparkViewFactory viewFactory) { var batch = new SparkBatchDescriptor(); batch.For<HomeController>().For<ManageController>(); viewFactory.Precompile(batch); } As you can see there are quite a few of things going on in the above code, Registering the ViewEngine, Compiling the Views, Registering the Routes/Controllers/Model Binders, Settings up Logger, Validations and as you can imagine the more it becomes complex the more things will get added in the application start. One of the goal of the MVCExtensions is to reduce the above design smell. Instead of writing all the plumbing code in the application start, it contains BootstrapperTask to register individual services. Out of the box, it contains BootstrapperTask to register Controllers, Controller Factory, Action Invoker, Action Filters, Model Binders, Model Metadata/Validation Providers, ValueProvideraFactory, ViewEngines etc and it is intelligent enough to automatically detect the above types and register into the ASP.NET MVC Framework. Other than the built-in tasks you can create your own custom task which will be automatically executed when the application starts. When the BootstrapperTasks are in action you will find the global.asax pretty much clean like the following: public class MvcApplication : UnityMvcApplication { public void ErrorLog_Filtering(object sender, ExceptionFilterEventArgs e) { Check.Argument.IsNotNull(e, "e"); HttpException exception = e.Exception.GetBaseException() as HttpException; if ((exception != null) && (exception.GetHttpCode() == (int)HttpStatusCode.NotFound)) { e.Dismiss(); } } } The above code is taken from my another open source project Shrinkr, as you can see the global.asax is longer cluttered with any plumbing code. One special thing you have noticed that it is inherited from the UnityMvcApplication rather than regular HttpApplication. There are separate version of this class for each IoC Container like NinjectMvcApplication, StructureMapMvcApplication etc. Other than executing the built-in tasks, the Shrinkr also has few custom tasks which gets executed when the application starts. For example, when the application starts, we want to ensure that the default users (which is specified in the web.config) are created. The following is the custom task that is used to create those default users: public class CreateDefaultUsers : BootstrapperTask { protected override TaskContinuation ExecuteCore(IServiceLocator serviceLocator) { IUserRepository userRepository = serviceLocator.GetInstance<IUserRepository>(); IUnitOfWork unitOfWork = serviceLocator.GetInstance<IUnitOfWork>(); IEnumerable<User> users = serviceLocator.GetInstance<Settings>().DefaultUsers; bool shouldCommit = false; foreach (User user in users) { if (userRepository.GetByName(user.Name) == null) { user.AllowApiAccess(ApiSetting.InfiniteLimit); userRepository.Add(user); shouldCommit = true; } } if (shouldCommit) { unitOfWork.Commit(); } return TaskContinuation.Continue; } } There are several other Tasks in the Shrinkr that we are also using which you will find in that project. To create a custom bootstrapping task you have create a new class which either implements the IBootstrapperTask interface or inherits from the abstract BootstrapperTask class, I would recommend to start with the BootstrapperTask as it already has the required code that you have to write in case if you choose the IBootstrapperTask interface. As you can see in the above code we are overriding the ExecuteCore to create the default users, the MVCExtensions is responsible for populating the ServiceLocator prior calling this method and in this method we are using the service locator to get the dependencies that are required to create the users (I will cover the custom dependencies registration in the next post). Once the users are created, we are returning a special enum, TaskContinuation as the return value, the TaskContinuation can have three values Continue (default), Skip and Break. The reason behind of having this enum is, in some special cases you might want to skip the next task in the chain or break the complete chain depending upon the currently running task, in those cases you will use the other two values instead of the Continue. The last thing I want to cover in the bootstrapping task is the Order. By default all the built-in tasks as well as newly created task order is set to the DefaultOrder(a static property), in some special cases you might want to execute it before/after all the other tasks, in those cases you will assign the Order in the Task constructor. For Example, in Shrinkr, we want to run few background services when the all the tasks are executed, so we assigned the order as DefaultOrder + 1. Here is the code of that Task: public class ConfigureBackgroundServices : BootstrapperTask { private IEnumerable<IBackgroundService> backgroundServices; public ConfigureBackgroundServices() { Order = DefaultOrder + 1; } protected override TaskContinuation ExecuteCore(IServiceLocator serviceLocator) { backgroundServices = serviceLocator.GetAllInstances<IBackgroundService>().ToList(); backgroundServices.Each(service => service.Start()); return TaskContinuation.Continue; } protected override void DisposeCore() { backgroundServices.Each(service => service.Stop()); } } That’s it for today, in the next post I will cover the custom service registration, so stay tuned.

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Parallelism in .NET – Part 8, PLINQ’s ForAll Method

- by Reed

Parallel LINQ extends LINQ to Objects, and is typically very similar. However, as I previously discussed, there are some differences. Although the standard way to handle simple Data Parellelism is via Parallel.ForEach, it’s possible to do the same thing via PLINQ. PLINQ adds a new method unavailable in standard LINQ which provides new functionality… LINQ is designed to provide a much simpler way of handling querying, including filtering, ordering, grouping, and many other benefits. Reading the description in LINQ to Objects on MSDN, it becomes clear that the thinking behind LINQ deals with retrieval of data. LINQ works by adding a functional programming style on top of .NET, allowing us to express filters in terms of predicate functions, for example. PLINQ is, generally, very similar. Typically, when using PLINQ, we write declarative statements to filter a dataset or perform an aggregation. However, PLINQ adds one new method, which provides a very different purpose: ForAll. The ForAll method is defined on ParallelEnumerable, and will work upon any ParallelQuery<T>. Unlike the sequence operators in LINQ and PLINQ, ForAll is intended to cause side effects. It does not filter a collection, but rather invokes an action on each element of the collection. At first glance, this seems like a bad idea. For example, Eric Lippert clearly explained two philosophical objections to providing an IEnumerable<T>.ForEach extension method, one of which still applies when parallelized. The sole purpose of this method is to cause side effects, and as such, I agree that the ForAll method “violates the functional programming principles that all the other sequence operators are based upon”, in exactly the same manner an IEnumerable<T>.ForEach extension method would violate these principles. Eric Lippert’s second reason for disliking a ForEach extension method does not necessarily apply to ForAll – replacing ForAll with a call to Parallel.ForEach has the same closure semantics, so there is no loss there. Although ForAll may have philosophical issues, there is a pragmatic reason to include this method. Without ForAll, we would take a fairly serious performance hit in many situations. Often, we need to perform some filtering or grouping, then perform an action using the results of our filter. Using a standard foreach statement to perform our action would avoid this philosophical issue: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action foreach (var item in filteredItems) { // These will now run serially item.DoSomething(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This would cause a loss in performance, since we lose any parallelism in place, and cause all of our actions to be run serially. We could easily use a Parallel.ForEach instead, which adds parallelism to the actions: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action once the filter completes Parallel.ForEach(filteredItems, item => { // These will now run in parallel item.DoSomething(); }); This is a noticeable improvement, since both our filtering and our actions run parallelized. However, there is still a large bottleneck in place here. The problem lies with my comment “perform an action once the filter completes”. Here, we’re parallelizing the filter, then collecting all of the results, blocking until the filter completes. Once the filtering of every element is completed, we then repartition the results of the filter, reschedule into multiple threads, and perform the action on each element. By moving this into two separate statements, we potentially double our parallelization overhead, since we’re forcing the work to be partitioned and scheduled twice as many times. This is where the pragmatism comes into play. By violating our functional principles, we gain the ability to avoid the overhead and cost of rescheduling the work: // Perform an action on the results of our filter collection .AsParallel() .Where( i => i.SomePredicate() ) .ForAll( i => i.DoSomething() ); The ability to avoid the scheduling overhead is a compelling reason to use ForAll. This really goes back to one of the key points I discussed in data parallelism: Partition your problem in a way to place the most work possible into each task. Here, this means leaving the statement attached to the expression, even though it causes side effects and is not standard usage for LINQ. This leads to my one guideline for using ForAll: The ForAll extension method should only be used to process the results of a parallel query, as returned by a PLINQ expression. Any other usage scenario should use Parallel.ForEach, instead.

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Parallelism in .NET – Part 17, Think Continuations, not Callbacks

- by Reed

In traditional asynchronous programming, we’d often use a callback to handle notification of a background task’s completion. The Task class in the Task Parallel Library introduces a cleaner alternative to the traditional callback: continuation tasks. Asynchronous programming methods typically required callback functions. For example, MSDN’s Asynchronous Delegates Programming Sample shows a class that factorizes a number. The original method in the example has the following signature: public static bool Factorize(int number, ref int primefactor1, ref int primefactor2) { //... .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } However, calling this is quite “tricky”, even if we modernize the sample to use lambda expressions via C# 3.0. Normally, we could call this method like so: int primeFactor1 = 0; int primeFactor2 = 0; bool answer = Factorize(10298312, ref primeFactor1, ref primeFactor2); Console.WriteLine("{0}/{1} [Succeeded {2}]", primeFactor1, primeFactor2, answer); If we want to make this operation run in the background, and report to the console via a callback, things get tricker. First, we need a delegate definition: public delegate bool AsyncFactorCaller( int number, ref int primefactor1, ref int primefactor2); Then we need to use BeginInvoke to run this method asynchronously: int primeFactor1 = 0; int primeFactor2 = 0; AsyncFactorCaller caller = new AsyncFactorCaller(Factorize); caller.BeginInvoke(10298312, ref primeFactor1, ref primeFactor2, result => { int factor1 = 0; int factor2 = 0; bool answer = caller.EndInvoke(ref factor1, ref factor2, result); Console.WriteLine("{0}/{1} [Succeeded {2}]", factor1, factor2, answer); }, null); This works, but is quite difficult to understand from a conceptual standpoint. To combat this, the framework added the Event-based Asynchronous Pattern, but it isn’t much easier to understand or author. Using .NET 4’s new Task<T> class and a continuation, we can dramatically simplify the implementation of the above code, as well as make it much more understandable. We do this via the Task.ContinueWith method. This method will schedule a new Task upon completion of the original task, and provide the original Task (including its Result if it’s a Task<T>) as an argument. Using Task, we can eliminate the delegate, and rewrite this code like so: var background = Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }); background.ContinueWith(task => Console.WriteLine("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result)); This is much simpler to understand, in my opinion. Here, we’re explicitly asking to start a new task, then continue the task with a resulting task. In our case, our method used ref parameters (this was from the MSDN Sample), so there is a little bit of extra boiler plate involved, but the code is at least easy to understand. That being said, this isn’t dramatically shorter when compared with our C# 3 port of the MSDN code above. However, if we were to extend our requirements a bit, we can start to see more advantages to the Task based approach. For example, supposed we need to report the results in a user interface control instead of reporting it to the Console. This would be a common operation, but now, we have to think about marshaling our calls back to the user interface. This is probably going to require calling Control.Invoke or Dispatcher.Invoke within our callback, forcing us to specify a delegate within the delegate. The maintainability and ease of understanding drops. However, just as a standard Task can be created with a TaskScheduler that uses the UI synchronization context, so too can we continue a task with a specific context. There are Task.ContinueWith method overloads which allow you to provide a TaskScheduler. This means you can schedule the continuation to run on the UI thread, by simply doing: Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }).ContinueWith(task => textBox1.Text = string.Format("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result), TaskScheduler.FromCurrentSynchronizationContext()); This is far more understandable than the alternative. By using Task.ContinueWith in conjunction with TaskScheduler.FromCurrentSynchronizationContext(), we get a simple way to push any work onto a background thread, and update the user interface on the proper UI thread. This technique works with Windows Presentation Foundation as well as Windows Forms, with no change in methodology.

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Free WebCamps - North America, Asia and Europe - Sign Up Now

- by Latest Microsoft Blogs

A few days ago on Twitter @ red7_liu tweeted: ???Web Camps???????,??Scott Hanselman??. This part "??" as I understand, effectively means "Big Cow." "Microsoft Web Camps Conference is coming to China, Big Cow Scott Hanselman will Read More......(read more)

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low speed web application, Server problem or Application

- by Ashian

Hi, I have a web application written by asp.net (c#) sql server 2005. we host it on 2 dedicated server ( IIS and SQL server ) From some month ago , in some days of week we have many reports about speed issue. we have some other application on this server using same database. when we have speed problem all aplication on these server have this problem, but applications on other server in same data center work correctly. ram and cpu usage are ok. how can I check that the problem related to internet connection or my application design? which parameters must be checked. Some other information In applications users can upload several files to server , each file up to 3 MB. we use a sql web admin application, on same server that has same problem, this is a standard application which work perfectly on other servers. Thanks

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