WCF service interaoperability with a Webservice

I'm not so sure you even have to wrap the service. If the service is publishing a WSDL, you can generate client code and config with svcutil. It shouldn't matter what kind of framework the webservice was built on. Here's how I would try to do this:

- Generate config and client proxy code with svcutil. I like to have a local copy of the WSDL to look at, so I do this:

svcutil.exe /t:metadata <WSDL URL>

Now that I have a local copy of a .wsdl and .xsd file, I generate code and config using:

svcutil.exe <wsdl file> <xsd file>

- Rename that .config file from Output.config to App.config. Look at the generated client code. This makes some kind of client class that can be instanciated and service methods can be called, just like the vast majority of WCF samples.

Now, if you still want to wrap the service, I think the way to do it would be to wrap the WCF client above in a WCF service. Basically, each WCF service operation would end up being a WCF client proxy which is used to call methods on the outside service. But, if everything is wrapped correctly, the WSDL from your WCF service would be pretty much identical to the one from the outside service, so why do all that extra work?

HTH,

-James

JamesOsborne-MSFT at 2007-10-3 >

To clarify things, I'll try to describe your scenario like this:

Given an "external" service A, you want to wrap service A with a WCF service B. WCF clients will access only service B. So, the WCF service B can be viewed as an intermediary. Sometimes people would do this because service B adds new functionality while still providing everything that service A provides.

Here's how I would create service B:

1. Figure out what service operations (maybe all of them) from service A that I need to provide with service B.

2. Define the contract (interfaces) for these operations. I could do this with svcutil or I could do it manually by hand. If there are only a couple operations, it might be faster just to write them by hand.

3. Define a service class which implements this contract.

4. Implement the methods (operations) in the service class. The implementation looks a lot like a WCF client. I would have the address for the endpoint at service A, the binding that the endpoint requires, and I would use those and the contract for service A's method that I'm wrapping to create a channel factory, then a channel. Then I would call that method at service A and return whatever is needed.

In code, it would look something like this: (note: I didn't build this or anything, but this should illustrate the 4 steps above)

// Contract for Service A

[ServiceContract]

public interface IServiceAContract

{

[OperationContract]

int AddTwoNumbers(int x, int y);

}

// So, I have to wrap one operation. I'll define the service contract for this. It is pretty much identical, but if I wanted to implement new methods as well, I would do that here.

// Contract for Service B

[ServiceContract]

public interface IServiceBContract

{

[OperationContract]

int AddTwoNumbers(int x, int y);

}

// Now my WCF service class (service B) which uses IServiceBContract

[ServiceBehavior]

public class ServiceB : IServiceBContract

{

private string serviceAEndpointAddress = http://serviceA;'

// The binding used for serviceA is defined in config. I could do it in code here, too, but it depends on the requirements of serviceA.

private BasicHttpBinding binding = new BasicHttpBinding("ServiceABindingConfiguration");

[OperationBehavior]

public int AddTwoNumbers(int x, int y);

{

ChannelFactory<IServiceAContract> factory = new ChannelFactory<IServiceAContract>(this.binding, this.serviceAEndpointAddress);

IServiceAContract channel = factory.CreateChannel();

((IChannel)channel).Open();

return channel.AddTwoNumbers(x, y);

}

}

Does this help at all? Or am I not understanding your scenario?

Thanks,

James

JamesOsborne-MSFT at 2007-10-3 >

Minor detail: the operation defined on IServiceBContract is Add2Numbers, but in the service implementation of that contract, the method is named AddTwoNumbers. I'm assuming the latter is just a typo that doesn't exist in your actual code?

Your Client won't be calling your webservice Add() method. It only can access the methods at ServiceB, which above is Add2Numbers.

You are getting exceptions because the Client hasn't created a channel to the ServiceB. You need to do the same thing you did in the ServiceB methods, but for the client:

// This will make a factory for creating channels to the service, using the binding and address specified in the constructor.

ChannelFactory<IServiceBContract> factory = new ChannelFactory<IServiceBContract>(binding, serviceBEndpointAddress);

IServiceBContract clientChannel = factory.CreateChannel();

((IChannel)clientChannel).Open();

double addedNumbers = clientChannel.Add2Numbers(5, 5);

((IChannel)clientChannel).Close();

Console.Writeline(addedNumbers);

If you are interested, I can post a working sample that has a WCF serviceA, WCF serviceB, and Client which only communicates directly with serviceB. It works nicely, but it's all WCF; I haven't done anything with asmx.

-James

JamesOsborne-MSFT at 2007-10-3 >

Thanks for the reply,

I created the channel factory at client side also but still i am getting tha same error, as follows:

The exception Message is:

System.Web.Services.Protocols.SoapException: Server did not recognize the value of HTTP Header SOAPAction: http://tempuri.org/IServiceAContract/AddTwoNumbers.

at System.Web.Services.Protocols.Soap11ServerProtocolHelper.RouteRequest()

at System.Web.Services.Protocols.SoapServerProtocol.RouteRequest(SoapServerMessage message)

at System.Web.Services.Protocols.SoapServerProtocol.Initialize()

at System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type, HttpContext context, HttpRequest request, HttpResponse response, Boolean& abortProcessing)

and the Stack Trace for the Method is:

System.ServiceModel.Channels.ServiceChannel.HandleReply(ProxyOperationRuntime operation, ProxyRpc&amp; rpc)
System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs)
System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData&amp; msgData, Int32 type)
IServiceBContract.Add(Double A, Double B)
client.Program.Main(String[] args)
System.AppDomain.nExecuteAssembly(Assembly assembly, String[] args)
System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
System.Threading.ThreadHelper.ThreadStart_Context(Object state)
System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
System.Threading.ThreadHelper.ThreadStart()

ramkasarla at 2007-10-3 >

i used SvcTraceViewer tool to trace the exception details which i posted above and when I examine the trace log files of both service and client i could see the same exception details which i posted above in SvcTraceViewer tool. and i am once again posting my whole application,which is as follows:

my asmx service :

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ToolboxItem(false)]
public class Service1 : System.Web.Services.WebService
{

[WebMethod]
public double AddTwoNumbers(double A, double B)
{
return A + B;
}
}

MY WCF service :

[ServiceContract]
public interface IServiceAContract
{
[OperationContract]
double AddTwoNumbers(double A, double B);
}

[ServiceContract]
public interface IServiceBContract
{
[OperationContract]
double Add(double A, double B);
}

public class ServiceB : IServiceBContract
{

private string serviceAEndpointAddress = " http://localhost:50171/Service1.asmx";
private BasicHttpBinding binding = new BasicHttpBinding();
[OperationBehavior]
public double Add(double A, double B)
{

ChannelFactory<IServiceAContract> factory = new ChannelFactory<IServiceAContract>(this.binding, this.serviceAEndpointAddress);
IServiceAContract channel = factory.CreateChannel();

((IChannel)channel).Open();
return channel.AddTwoNumbers(A, B);

}

}

My Client Application :

static void Main(string[] args)
{
EndpointAddress address = new EndpointAddress("http://localhost/MYWCFServiceLibrary/service.svc");
BasicHttpBinding binding = new BasicHttpBinding();
ChannelFactory<IServiceBContract> factory = new ChannelFactory<IServiceBContract>(binding,address);
IServiceBContract cchannel = factory.CreateChannel();
((IChannel)cchannel).Open();
double Result = cchannel.Add(7, 8);
((IChannel)cchannel).Close();
Console.WriteLine("Result is :", Result);
Console.ReadLine();
}

and James could you post the working sample as service A and Service B as you said above.

ramkasarla at 2007-10-3 >

My WebService WSDL is as follows:

ramkasarla at 2007-10-3 >

Hi James,

I did changes in my code as you suggested but and I am getting the exception as follows:

System.Web.Services.Protocols.SoapException: Server did not recognize the value of HTTP Header SOAPAction: http://tempuri.org/Service1Soap/AddTwoNumbers.

Is there any other way to achieve my task, as I said above .

ramkasarla at 2007-10-3 >