Cannot connect to a WCF service hosted in a Worker Role

Question

I've created a WCF service and hosted it in cloud through a worker role. Unfortunately when I try to connect to the worker role service I get an exception with the message: "No DNS entries exist for host 3a5c0cdffcf04d069dbced5e590bca70.cloudapp.net." 3a5c0cdffcf04d069dbced5e590bca70.cloudapp.net is the address for the worker role deployed in azure staging environment. The workerrole.cs has the following code to expose the WCF service:

    public override void Run()
    {
        using (ServiceHost host = new ServiceHost(typeof(MyService)))
        {
            string ip = RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["tcppoint"].IPEndpoint.Address.ToString();
            int tcpport = RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["tcppoint"].IPEndpoint.Port;
            int mexport = RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["mexinput"].IPEndpoint.Port;

            // Add a metadatabehavior for client proxy generation
            // The metadata is exposed via net.tcp
            ServiceMetadataBehavior metadatabehavior = new ServiceMetadataBehavior();
            host.Description.Behaviors.Add(metadatabehavior);
            Binding mexBinding = MetadataExchangeBindings.CreateMexTcpBinding();
            string mexlistenurl = string.Format("net.tcp://{0}:{1}/MyServiceMetaDataEndpoint", ip, mexport);
            string mexendpointurl = string.Format("net.tcp://{0}:{1}/MyServiceMetaDataEndpoint", RoleEnvironment.GetConfigurationSettingValue("Domain"), 8001);
            host.AddServiceEndpoint(typeof(IMetadataExchange), mexBinding, mexendpointurl, new Uri(mexlistenurl));

            // Add the endpoint for MyService
            string listenurl = string.Format("net.tcp://{0}:{1}/MyServiceEndpoint", ip, tcpport);
            string endpointurl = string.Format("net.tcp://{0}:{1}/MyServiceEndpoint", RoleEnvironment.GetConfigurationSettingValue("Domain"), 9001);
            host.AddServiceEndpoint(typeof(IMyService), new NetTcpBinding(SecurityMode.None), endpointurl, new Uri(listenurl));
            host.Open();

            while (true)
            {
                Thread.Sleep(100000);
                Trace.WriteLine("Working", "Information");
            }
        }
    } 

The tcppoint and mexinput are configured with the ports 8001 and 9001. Also Domain is configured with worker role deployment url:3a5c0cdffcf04d069dbced5e590bca70.cloudapp.net

On the client part(a console app), we are using the following configuration in app.config::

    <bindings>
        <netTcpBinding>
            <binding name="NetTcpBinding_IMyService" closeTimeout="00:01:00"
                openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00"
                transactionFlow="false" transferMode="Buffered" transactionProtocol="OleTransactions"
                hostNameComparisonMode="StrongWildcard" listenBacklog="10"
                maxBufferPoolSize="524288" maxBufferSize="65536" maxConnections="10"
                maxReceivedMessageSize="65536">
                <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384"
                    maxBytesPerRead="4096" maxNameTableCharCount="16384" />
                <reliableSession ordered="true" inactivityTimeout="00:50:00"
                    enabled="false" />
                <security mode="None">
                    <transport clientCredentialType="Windows" protectionLevel="EncryptAndSign" />
                    <message clientCredentialType="Windows" />
                </security>
            </binding>
        </netTcpBinding>

    </bindings>
    <client>
      <endpoint address="httpp:\\3a5c0cdffcf04d069dbced5e590bca70.cloudapp.net:9001/MyServiceEndpoint" binding="netTcpBinding"
         bindingConfiguration="NetTcpBinding_IMyService" contract="ServiceReference1.IMyService"
         name="NetTcpBinding_IMyService" />
    </client>

  <behaviors>
    <serviceBehaviors>
      <behavior name="behave">
        <serviceMetadata httpGetEnabled="false"/>
      </behavior>
    </serviceBehaviors>
  </behaviors>   

</system.serviceModel>
<system.net>
  <defaultProxy useDefaultCredentials="true">
  <proxy autoDetect="False" usesystemdefault="False" bypassonlocal="True" />
</defaultProxy>

The following code is built using the sample code available in msdn as background. Locally it is working fine. Unfortunately when i deploy it to cloud, the exception occurs. Moreover, when i use the virtual ip instead of the url, a connection time out occurs with the exception the remote machine did not respond.

Answer 1

Looks like you have your service setup to listen on net.tcp (TCP) and your client using http bindings. I would not expect that to work even locally. I am assuming you have actually opened port 9000 in the ServiceDefinition. Remember that will be a load-balanced endpoint. Are you trying to communicate to this instance from within the deployment (inter-role) or from outside the cloud?

I have found it is a lot easier to setup the host and client (when communicating within a role) through code. Try this:

http://dunnry.com/blog/2010/05/28/HostingWCFInWindowsAzure.aspx

If you are trying to hit the service from a client outside the deployment, this still applies, but for the client building part. You will need to use the external DNS name and port defined in ServiceDefinition.

I have also seen DNS errors if you try to hit the endpoint too soon before the role was ready. It can take a bit to propogate the DNS and you should try not to resolve it until it is ready, lest you cache a bogus DNS entry. If you can resolve that DNS name however to your VIP address, that is not the issue.

Answer 2

    public void CallWebService(string data)
    {

        try
        {
            string uri = "url"+data;

            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();

            Stream str = response.GetResponseStream();

            StreamReader sr = new StreamReader(str);

            String IResponse = sr.ReadToEnd();


        }
        catch (Exception ex)
        {
            System.Console.WriteLine("Message: "+ex.Message);
        }

    }

Hope it helps you.