HttpContext.Current.Session is null while calling async webservices

Question

I'm working on a Asp.Net 3.5 Web Application which requires Async Web service calls. Here is some code. I have written the code for Async calling using delegates but somehow my HttpContext.Current.Session is null. To make sure, I even tried passing HttpContext.

static HttpContext httpContext;
public void AsyncGetUser()
        {
            httpContext = HttpContext.Current;//not getting Session as null here

            GetUserDelegate delegate = new GetUserDelegate(InvokeWrapperMethod);
            IAsyncResult async = delegate.BeginInvoke(httpContext,new AsyncCallback(CallbackMethod), null);

        }
static void CallbackMethod(IAsyncResult ar)
        {
            AsyncResult result = (AsyncResult)ar;
            GetUserDelegate caller = (GetUserDelegate)result.AsyncDelegate;
            caller.EndInvoke(ar);

        }
private static void InvokeWrapperMethod(HttpContext hc)
        {
            HttpContext.Current = hc; //getting Session as null here
            UserInfo userInfo = Service.GetUserInfo();
            SetInSession(USER_INFO, userInfo);
        }

I have tried <modules runAllManagedModulesForAllRequests="true"> and

<system.webServer>
<modules>

  <remove name="Session"/>
  <add name="Session" type="System.Web.SessionState.SessionStateModule"/>

</modules>

as this SO question suggested but didn't work. I would appreciate if you guys could give some pointers. Thanks.

score 1 · Answer 1 · answered Jun 28 '13 at 10:17

1

This can occur in ASP.NET apps using the async/await (TAP) pattern. To solve this, you need to add this to your appSettings section in web.config.

<add key="aspnet:UseTaskFriendlySynchronizationContext" value="true"/>

This may require .NET 4.5, I note you are not using this version but I add this answer here for others that have upgraded projects and are hitting this issue with their TAP code.

answered Jun 28 '13 at 10:17

Luke Puplett

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Thanks for the post. We were running .net 3.5 (& still do). Hopefully sometime soon we'll upgrade to 4.0 which, I hear, handles async better than 3.5. – Venkata Krishna Jun 28 '13 at 18:57

score 0 · Answer 2 · answered Apr 24 '12 at 21:14

0

your web service should use , IRequiresSessionState marker interface to enable session.

answered Apr 24 '12 at 21:14

adt

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On what class? When calling BeginInvoke on a delegate, no interface is involved. Or is it? – Schultz9999 Mar 15 '13 at 21:12

score 0 · Accepted Answer · answered Apr 26 '12 at 20:51

0

I ended up with the decision to refactor the whole project.

answered Apr 26 '12 at 20:51

Venkata Krishna

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Luke Puplett · Answer 4 · 2013-07-01T09:45:19.013

It might be that you're using delegates to get the 'handy' BeginInvoke method. This is inefficient since behind the scenes, its using a load of Reflection. If the background work is always significant then this overhead gets amortised, but its its sometimes just a few reads, then it'll take longer than doing it on the original thread.

You could install RX for 3.5 and use the 'mini TPL' to get at Tasks. This in itself could solve the problem (the issue might be the way in which that delegate.BeginInvoke is written), else try passing the context in as the state instance.

I know you've refactored out of the problem (probably a good thing) but I add this answer for completeness having looked more at what you were originally doing.

HttpContext.Current.Session is null while calling async webservices

4 Answers4