How to change the timeout on a NET WebClient object

Question

I am trying to download a client s data to my local machine  programatically  and their webserver is very  very slow which is causing a timeout in my WebClient object   Here is my code   WebClient webClient   new WebClient     webClient Encoding   Encoding UTF8  webClient DownloadFile downloadUrl  downloadFile     Is there a way to set an infinite timeout on this object  Or if not can anyone help me with an example on an alternate way to do this   The URL works fine in a browser - it just takes about 3 minutes to show

User · Answer

The first solution did not work for me but here is some code that did work for me       private class WebClient   System Net WebClient               public int Timeout   get  set             protected override WebRequest GetWebRequest Uri uri                        WebRequest lWebRequest   base GetWebRequest uri               lWebRequest Timeout   Timeout                HttpWebRequest lWebRequest  ReadWriteTimeout   Timeout              return lWebRequest                       private string GetRequest string aURL                using  var lWebClient   new WebClient                          lWebClient Timeout   600   60   1000              return lWebClient DownloadString aURL

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I had to fight with this issue yesterday and I ve also ended up to write my custom extension class  As you can see by looking at the code below and comparing it with the accepted answer  I tried to tweak the suggestion a little bit more in order to have a more versatile class  this way you can set a precise timeout either upon instancing the object or right before using a method that uses the internal WebRequest handler  using System  using System Net   namespace Ryadel Components Web            lt summary gt          An extension of the standard System Net WebClient         featuring a customizable constructor and  Timeout  property           lt  summary gt      public class RyadelWebClient   WebClient                    lt summary gt              Default constructor  30000 ms timeout              NOTE  timeout can be changed later on using the  Timeout  property               lt  summary gt          public RyadelWebClient     this 30000                    lt summary gt              Constructor with customizable timeout              lt  summary gt               lt param name  quot timeout quot  gt              Web request timeout  in milliseconds               lt  param gt          public RyadelWebClient int timeout                        Timeout   timeout                      region Methods         protected override WebRequest GetWebRequest Uri uri                        WebRequest w   base GetWebRequest uri               w Timeout   Timeout                HttpWebRequest w  ReadWriteTimeout   Timeout              return w                     endregion               lt summary gt              Web request timeout  in milliseconds               lt  summary gt          public int Timeout   get  set             While I was there  I also took the chance to lower the default Timeout value to 30 seconds  as 100 seemed way too much for me  In case you need additional info regarding this class or how to use it  check out this post I wrote on my blog

User · Answer

In some cases it is necessary to add user agent to headers   WebClient myWebClient   new WebClient    myWebClient DownloadFile myStringWebResource  fileName   myWebClient Headers  User-Agent      Mozilla 4 0  Compatible  Windows NT 5 1  MSIE 6 0   compatible  MSIE 6 0  Windows NT 5 1   NET CLR 1 1 4322   NET CLR 2 0 50727      This was the solution to my case   Credit   http   genjurosdojo blogspot com 2012 10 the-remote-server-returned-error-504 html

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CORRECTED VERSION OF LAST FUNCTION IN VISUAL BASIC BY GLENNG  Protected Overrides Function GetWebRequest ByVal address As System Uri  As System Net WebRequest             Dim w As System Net WebRequest   MyBase GetWebRequest address              If  TimeoutMS  lt  gt  0 Then                 w Timeout    TimeoutMS             End If             Return w    lt  lt  lt  NOTICE  MyBase GetWebRequest address  DOES NOT WORK  gt  gt  gt          End Function

User · Answer

You can extend the timeout  inherit the original WebClient class and override the webrequest getter to set your own timeout  like in the following example   MyWebClient was a private class in my case   private class MyWebClient   WebClient       protected override WebRequest GetWebRequest Uri uri                WebRequest w   base GetWebRequest uri           w Timeout   20   60   1000          return w

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Usage   using  var client   new TimeoutWebClient TimeSpan FromSeconds 10          return await client DownloadStringTaskAsync url  ConfigureAwait false       Class   using System  using System Net   namespace Utilities       public class TimeoutWebClient   WebClient               public TimeSpan Timeout   get  set             public TimeoutWebClient TimeSpan timeout                        Timeout   timeout                     protected override WebRequest GetWebRequest Uri uri                        var request   base GetWebRequest uri               if  request    null                                return null                             var timeoutInMilliseconds    int  Timeout TotalMilliseconds               request Timeout   timeoutInMilliseconds              if  request is HttpWebRequest httpWebRequest                                httpWebRequest ReadWriteTimeout   timeoutInMilliseconds                             return request                      But I recommend a more modern solution   using System  using System Net Http  using System Threading  using System Threading Tasks   public static async Task lt string gt  ReadGetRequestDataAsync Uri uri  TimeSpan  timeout   null  CancellationToken cancellationToken   default        using var source   CancellationTokenSource CreateLinkedTokenSource cancellationToken       if  timeout    null                source CancelAfter timeout Value              using var client   new HttpClient        using var response   await client GetAsync uri  source Token  ConfigureAwait false        return await response Content ReadAsStringAsync   ConfigureAwait false       It will throw an OperationCanceledException after a timeout

User · Answer

You need to use HttpWebRequest rather than WebClient as you can t set the timeout on WebClient without extending it  even though it uses the HttpWebRequest   Using the HttpWebRequest instead will allow you to set the timeout

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Couldn t get the w Timeout code to work when pulled out the network cable  it just wasn t timing out  moved to using HttpWebRequest and does the job now   HttpWebRequest request    HttpWebRequest WebRequest Create downloadUrl   request Timeout   10000  request ReadWriteTimeout   10000  var wresp    HttpWebResponse request GetResponse     using  Stream file   File OpenWrite downloadFile         wresp GetResponseStream   CopyTo file

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According to kisp solution this is my edited version working async  Class WebConnection cs internal class WebConnection   WebClient       internal int Timeout   get  set         protected override WebRequest GetWebRequest Uri Address                WebRequest WebReq   base GetWebRequest Address           WebReq Timeout   Timeout   1000    Seconds         return WebReq           The async Task private async Task GetDataAsyncWithTimeout         await Task Run      gt                using  WebConnection webClient   new WebConnection                          webClient Timeout   5     Five seconds             webClient DownloadData  quot https   www yourwebsite com quot                           await GetDataAsyncWithTimeout    Else  if you don t want to use async  private void GetDataSyncWithTimeout         using  WebConnection webClient   new WebConnection                  webClient Timeout   5     Five seconds         webClient DownloadData  quot https   www yourwebsite com quot               GetDataSyncWithTimeout

User · Answer

As Sohnee says  using System Net HttpWebRequest and set the Timeout property instead of using System Net WebClient   You can t however set an infinite timeout value  it s not supported and attempting to do so will throw an ArgumentOutOfRangeException    I d recommend first performing a HEAD HTTP request and examining the Content-Length header value returned to determine the number of bytes in the file you re downloading and then setting the timeout value accordingly for subsequent GET request or simply specifying a very long timeout value that you would never expect to exceed

User · Answer

For anyone who needs a WebClient with a timeout that works for async task methods  the suggested solutions won t work  Here s what does work   public class WebClientWithTimeout   WebClient         10 secs default     public int Timeout   get  set      10000         for sync requests     protected override WebRequest GetWebRequest Uri uri                var w   base GetWebRequest uri           w Timeout   Timeout    10 seconds timeout         return w               the above will not work for async requests          let s create a workaround by hiding the method       and creating our own version of DownloadStringTaskAsync     public new async Task lt string gt  DownloadStringTaskAsync Uri address                var t   base DownloadStringTaskAsync address           if await Task WhenAny t  Task Delay Timeout      t    time out                        CancelAsync                      return await t            I blogged about the full workaround here

User · Answer

For completeness   here s kisp s solution ported to VB  can t add code to a comment   Namespace Utils       lt summary gt      Subclass of WebClient to provide access to the timeout property      lt  summary gt  Public Class WebClient     Inherits System Net WebClient      Private  TimeoutMS As Integer   0      Public Sub New           MyBase New       End Sub     Public Sub New ByVal TimeoutMS As Integer          MyBase New            TimeoutMS   TimeoutMS     End Sub          lt summary gt          Set the web call timeout in Milliseconds          lt  summary gt           lt value gt  lt  value gt      Public WriteOnly Property setTimeout   As Integer         Set ByVal value As Integer               TimeoutMS   value         End Set     End Property       Protected Overrides Function GetWebRequest ByVal address As System Uri  As System Net WebRequest         Dim w As System Net WebRequest   MyBase GetWebRequest address          If  TimeoutMS  lt  gt  0 Then             w Timeout    TimeoutMS         End If         Return w     End Function  End Class  End Namespace

[c#] How to change the timeout on a .NET WebClient object

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