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POHttpContext is null after await Task.Factory.FromAsync(BeginXxx, EndXxx)
 

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    <p>I have an Asp.Net application that calls some WCF service using a proxy generated by svcutil. The generated proxy has async methods in the APM pattern (BeginXxx, EndXxx).</p> <p>I am using the async targeting pack in order to leverage the new <code>async/await</code> pattern, and my target platform is .net 4.0 (otherwise I wouldn't have to use the async targeting pack).</p> <p>I am using <code>Task&lt;T&gt;.Factory.FromAsync</code> to convert the APM pattern into a Task that I can await.</p> <p>my code looks a little something like that (assuming the service method takes no parameters and returns an int:</p> <pre><code>int result = await Task&lt;int&gt;.Factory.FromAsync(proxy.BeginXxx, proxy.EndXxx, state: null); HttpContext.Current.Items["reuslt"] = result; </code></pre> <p>The second line throws a <code>NullReferenceException</code>.</p> <p>I am assuming that the reason is that the callback (which is everything that's running after the await call) does not have the original synchronization context.</p> <p>other methods (like Factory.StartNew) have <a href="http://msdn.microsoft.com/en-us/library/dd781658%28v=vs.100%29.aspx" rel="nofollow">overloads</a> that receive a <code>TaskScheduler</code> that can be used to preserve the context.</p> <p>The FromAsync Method also has <a href="http://msdn.microsoft.com/en-us/library/dd321413.aspx" rel="nofollow">overloads</a> that receive a <code>TaskScheduler</code>, but none that have the begin method as an argument.</p> <p>Assuming I do not want to start passing the Http context by hand as a method argument to all methods that get called after this line, how do I use the overload that gets a task scheduler or otherwise get .Net to respect my synchronization context?</p>
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    1. COAre you sure the synccontext was set correctly before the FromAsync call.
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    2. COBefore the FromAsync call I can access the HttpContext.
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