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Does anybody know if there are known issues or configuration gotchas with an IIS service connecting to an Azure based service?

I currently have a scenario that requires me to host two web-services, one in Azure, and one on a server running IIS. The IIS hosted service (a WCF service) connects to the Azure hosted service (actually the Azure storage API) in order to fetch certain information. This information is manipulated and returned to the client.

Client -> IIS Service -> Azure Storage Service

I'm running into issues with the IIS service connecting to the Azure Service. The hostname cannot be resolved. I'm using the Azure Storage client from my code, but have actually tried this using the azure API calls, and they also do not work from IIS. I captured the requests using Fiddler (on a different machine), they match the azure REST API calls, as expected. These requests, when made outside of IIS on the host machine execute properly. It is only when they are issued by the IIS service that they fail.

In my research other people have been running into this issue when there's a firewall problem, but since I can hit the service properly from the machine, that doesn't seem to fit the bill. My hunch is that there's a configuration issue I need to sort out in IIS, but I've failed to find anything useful with my searches.

Does anyone have any information on why this might be occuring (known bugs, gotchas etc)? Any workarounds? From a SOA perspective, this seems fairly critical to understand.

Any assitance anyone has would be helpful. Thank you.

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up vote 2 down vote accepted

Sounds like a proxy configuration issue. Check how your IIS server connected to Internet. If you are using some sort of proxy to get to Internet, that connection has to be configured correctly.

Specifically, if your proxy servers are Microsoft ISA server, or Microsoft Forefront TMG, then you need to check two things:

  1. ISA server client or Forefront TMG client software is installed on the server
  2. The account used by IIS application pool is domain user. ISA Server/TMG are designed to work only with user account, not service account. Alternative workaround for this limitation is using "defaultProxy" configuration in web.config, however it only wokrs for HTTP/HTTPS.

If you use different proxy server, then other issues might be involved, for example proxy might require authentication.

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Thanks. That was very helpful. I had to configure the default Proxy element with the proxy address. I just pulled that config out of IE, since the call was working in IE. <system.net> <defaultProxy> <proxy proxyaddress="myproxyserver"; bypassonlocal="true" /> </defaultProxy> </system.net> –  blackSphere Apr 27 '11 at 18:16
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