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I have a web application running on .net 4.0 and IIS7. When a form is submitted I have to invoke two external web services, wait for the responses, do something with it, and return the response. The problem is that the web services take about 20 seconds each to reply (this is beyond my control). I decided to move to an async approach so I can hit both services at the same time as oppose to hitting one wait for the response and then hitting the other one.

Now if I get 10 users submitting at the same time I will create 20 outbound requests on 20 separate threads. I read that IIS might not be so happy with this since the limit is set to 12 outbound TCP connections per CPU (maxconnections in machine.config). Can someone please confirm this? Is there anything else I should be thinking about in this particular scenario to ensure that IIS plays nicely?


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up vote 1 down vote accepted

you can override the maxconnection value in web.config as well.

  <add address="*" maxconnection="20"/> 

I am working on an application which also uses multiple external web services as data sources. Particular pages can make a dozen of async web service calls. So in our case maxconnection is set to 2000 in web.config and we do not observe outbound connections limitations.

The only thing to warn about, out app is still hosted in IIS6, so I'm not completely positive this will remain the same in IIS7. However, since maxconnection configuration is .NET-specific, not IIS-specific, I don't think this any change will happen.

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