title: Cancel async web service calls
body: <p>I need to be able to cancel async calls made to my webservice. One solution I have is to use manage my own threads, and use synchronous methods from the SOAP client. This works fine and it needs some more fine grained thread management.</p>
  
  <p>If I used any of these two patterns provided from adding a web service reference, say:</p>
  
  <pre><code>var Client = new ASL_WS.SvcSoapClient()
  IAsyncResult result = Client.BeginAuthenticateUser(Email, Password, new AsyncCallback(AuthCompleted));
  </code></pre>
  
  <p>or </p>
  
  <pre><code>var Client = new ASL_WS.SvcSoapClient()
  Client.AuthenticateUserCompleted += AuthCompleted;
  Client.AuthenticateUserAsync(Email, Passsword);
  </code></pre>
  
  <p>do any of these two patterns give me a way of cancelling the request? One use case could be: a user logs in, but wants to cancel before the authenticate call completes.</p>
  
  <p>Of course, I could implement this differently by modifying the asyncState passed to these calls, and setting it to disable UI update, but it's not what I'm looking for.</p>
  
  <p>Could I just just cancel all outstanding operations. Does Client.Abort() cancel such operations. What if there are many async requests, are all cancelled? Are there any other API methods that can do this?</p>