Global.asax

Post date: Mar 1, 2011 6:49:52 AM

• Application_BeginRequest() – fired when a request for the web application comes in.

• Application_AuthenticateRequest –fired just before the user credentials are authenticated. You can specify your own authentication logic over here.

• Application_AuthorizeRequest() – fired on successful authentication of user’s credentials. You can use this method to give authorization rights to user.

• Application_ResolveRequestCache() – fired on successful completion of an authorization request.

• Application_AcquireRequestState() – fired just before the session state is retrieved for the current request.

• Application_PreRequestHandlerExecute() - fired before the page framework begins before executing an event handler to handle the request.

• Application_PostRequestHandlerExecute() – fired after HTTP handler has executed the request.

• Application_ReleaseRequestState() – fired before current state data kept in the session collection is serialized.

• Application_UpdateRequestCache() – fired before information is added to output cache of the page.

  • Application_EndRequest() – fired at the end of each request

Methods corresponding to events that do not fire on each request

• Application_Start() – fired when the first resource is requested from the web server and the web application starts.

• Session_Start() – fired when session starts on each new user requesting a page.

• Application_Error() – fired when an error occurs.

• Session_End() – fired when the session of a user ends.

• Application_End() – fired when the web application ends.

• Application_Disposed() - fired when the web application is destroyed.

  • Show me an example!! Let us see an example of how to use the Global.asax to catch unhandled errors that occur at the application level.

  • To catch unhandled errors, do the following. Add a Global.asax file (Right click project > Add New Item > Global.asax). In the Application_Error() method, add the following code:

  •   

  • C#

  •  void Application_Error(object sender, EventArgs e)

  •     {

  •         // Code that runs when an unhandled error occurs

  •         Exception objErr = Server.GetLastError().GetBaseException();

  •         string err = "Error in: " + Request.Url.ToString() +

  •                           ". Error Message:" + objErr.Message.ToString();

  •          

  •     }

  • VB.NET

  •  

  • Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)

  •         ' Code that runs when an unhandled error occurs       

  •         Dim objErr As Exception = Server.GetLastError().GetBaseException()

  •         Dim err As String = "Error in: " & Request.Url.ToString() & ". Error Message:" & objErr.Message.ToString()

  •          

  •     End Sub

  •  

  • Here we make use of the Application_Error() method to capture the error using the Server.GetLastError().

Conclusion:

In this article, we learnt that Global.asax is a file used to declare application-level events and objects. The file is responsible for handling higher-level application events such as Application_Start, Application_End, Session_Start, Session_End, and so on. I would encourage you to explore the methods corresponding to the events and analyze the best possible methods to use them in your application, if needed.

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