simultaneous calls handling in WCF - wcf

Question

I'm new to .net and knows very little about WCF, so bear with me if any silly questions asked. I'm wondering how WCF handles simultaneous calls in SELF-HOST scenario if my code doesn't explicitly spawn any thread. So after read a lot on the stackoverflow, I created a test app but it seems not working. Please advise. Thanks a lot.
Please note ...
My question is only about WCF SELF HOSTING, so please don't refer to any IIS related.
I'm using webHttpBinding.
I understand there are maxConnection and service throttling settings, but I'm only interested in 2 simultaneous calls in my research setup. So there should be no max conn or thread pool concern.
My test service is NOT using session.
Code as below ...
namespace myApp
{
[ServiceContract(SessionMode = SessionMode.NotAllowed)]
public interface ITestService
{
[OperationContract]
[WebGet(UriTemplate="test?id={id}")]
string Test(int id);
}
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall,
ConcurrencyMode = ConcurrencyMode.Multiple)]
public class TestService : ITestService
{
private static ManualResetEvent done = new ManualResetEvent(false);
public string Test(int id)
{
if (id == 1)
{
done.Reset();
done.WaitOne();
}
else
{
done.Set();
}
}
}
}
app.config ...
<system.serviceModel>
<behaviors>
<endpointBehaviors>
<behavior name = "TestEndpointBehavior">
<webHttp/>
</behavior>
</endpointBehaviors>
</behaviors>
<services>
<service name = "myApp.TestService">
<endpoint address = "" behaviorConfiguration="TestEndpointBehavior"
binding = "webHttpBinding"
contract = "myApp.ITestService">
</endpoint>
<host>
<baseAddresses>
<add baseAddress="http://localhost:8080/test/"/>
</baseAddresses>
</host>
</service>
</services>
</system.serviceModel>
<system.web>
<sessionState mode = "Off" />
</system.web>
How I tested ...
Once had the application running, I opened my browser, FF in case, made one call to http://localhost:8080/test/test?id=1 . This request put the app to suspend waiting for signal, i.e. WaitOne. Then made another call in another browser tab to http://localhost:8080/test/test?id=2. What's expected is that this request will set the signal and thus the server will return for both requests.
But I saw the app hang and the Test function never got entered for the 2nd request. So apparently my code doesn't support simultaneous/concurrent calls. Anything wrong?

Answer 1

You can use single class to setup your wcf service and discard interface. You need to add global.asax file also. After you make the second call, all of them will return "finished".
This configuration does what you want.
Create TestService.cs with :
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall,
ConcurrencyMode = ConcurrencyMode.Multiple)]
[ServiceContract(SessionMode = SessionMode.NotAllowed)]
public class TestService
{
private static ManualResetEvent done = new ManualResetEvent(false);
[OperationContract]
[WebGet(UriTemplate = "test?id={id}")]
public string Test(int id)
{
if (id == 1)
{
done.Reset();
done.WaitOne();
}
else
{
done.Set();
}
return "finished";
}
}
web.config:
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.0" />
</system.web>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true" />
</system.webServer>
<system.serviceModel>
<standardEndpoints>
<webHttpEndpoint>
<!--
Configure the WCF REST service base address via the global.asax.cs file and the default endpoint
via the attributes on the <standardEndpoint> element below
-->
<standardEndpoint name="" helpEnabled="false" > </standardEndpoint>
</webHttpEndpoint>
</standardEndpoints>
<behaviors>
<serviceBehaviors>
<behavior>
<!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
<serviceMetadata httpGetEnabled="true" />
<!-- To receive exception details in faults for debugging purposes, set the value below to true. Set to false before deployment to avoid disclosing exception information -->
<serviceDebug includeExceptionDetailInFaults="false" />
</behavior>
</serviceBehaviors>
</behaviors>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
</system.serviceModel>
</configuration>
Global.asax file:
public class Global : System.Web.HttpApplication
{
protected void Application_Start(object sender, EventArgs e)
{
RouteTable.Routes.Add(new ServiceRoute("testservice", new WebServiceHostFactory(), typeof(TestService)));
}
}