Run WCF ServiceHost with multiple contracts

Question

Running a ServiceHost with a single contract is working fine like this:

servicehost = new ServiceHost(typeof(MyService1));
servicehost.AddServiceEndpoint(typeof(IMyService1), new NetTcpBinding(), "net.tcp://127.0.0.1:800/MyApp/MyService1");
servicehost.Open();

Now I'd like to add a second (3rd, 4th, ...) contract. My first guess would be to just add more endpoints like this:

servicehost = new ServiceHost(typeof(MyService1));
servicehost.AddServiceEndpoint(typeof(IMyService1), new NetTcpBinding(), "net.tcp://127.0.0.1:800/MyApp/MyService1");
servicehost.AddServiceEndpoint(typeof(IMyService2), new NetTcpBinding(), "net.tcp://127.0.0.1:800/MyApp/MyService2");
servicehost.Open();

But of course this does not work, since in the creation of ServiceHost I can either pass MyService1 as parameter or MyService2 - so I can add a lot of endpoints to my service, but all have to use the same contract, since I only can provide one implementation?
I got the feeling I'm missing the point, here. Sure there must be some way to provide an implementation for every endpoint-contract I add, or not?

Answer 1

You need to implement both services (interfaces) in the same class.

servicehost = new ServiceHost(typeof(WcfEntryPoint));
servicehost.Open(); 

public class WcfEntryPoint : IMyService1, IMyService2
{
    #region IMyService1
    #endregion

    #region IMyService2
    #endregion
}

---

FYI: I frequently use partial classes to make my host class code easier to read:

// WcfEntryPoint.IMyService1.cs
public partial class WcfEntryPoint : IMyService1
{
    // IMyService1 methods
}

// WcfEntryPoint.IMyService2.cs
public partial class WcfEntryPoint : IMyService2
{
    // IMyService2 methods
}

Answer 2

I'm currently faced with the same problem, and have decided to go with the implementation below. I'm not sure if there are any performance issues with having this many service contracts, but in my final implementation I will probably have about 10 - 15 service contracts, thus about 10-15 ServiceHosts.

I am hosting all my WCF services inside a single Windows Service.

private void PublishWcfEndpoints()
{
    var mappings = new Dictionary<Type, Type>
    {
       {typeof (IAuthenticationService), typeof (AuthenticationService)},
       {typeof(IUserService), typeof(UserService)},
       {typeof(IClientService), typeof(ClientService)}
    };


    foreach (var type in mappings)
    {
        Type contractType = type.Key;
        Type implementationType = type.Value;

        ServiceHost serviceHost = new ServiceHost(implementationType);
        ServiceEndpoint endpoint = serviceHost.AddServiceEndpoint(contractType, ServiceHelper.GetDefaultBinding(),
                                                                  Properties.Settings.Default.ServiceUrl  + "/" + contractType.Name);
        endpoint.Behaviors.Add(new ServerSessionBehavior());

        ServiceDebugBehavior serviceDebugBehaviour =
            serviceHost.Description.Behaviors.Find<ServiceDebugBehavior>();
        serviceDebugBehaviour.IncludeExceptionDetailInFaults = true;

        log.DebugFormat("Published Service endpoint: {0}", Properties.Settings.Default.ServiceUrl);

        serviceHost.Open();
        serviceHosts.Add(serviceHost);
    }

}

Feel free to comment on this type of set up, and if there are any issues with it, especially performance-related.

Answer 3

This answer is a further response to the comment in the accepted answer from chilltemp.

Sam, You really should determine why you need 10-50 contracts and try to find another solution. I looked over Juval Lowy's WCF Coding Standards (found on http://www.idesign.net/) and found the following references:

3 Service Contracts ... 4. Avoid contracts with one member. 5. Strive to have three to five members per service contract. 6. Do not have more than twenty members per service contract. Twelve is probably the practical limit.

He doesn't mention a limit on contract implementations (that I can find) but I can't imagine him viewing 50 contracts on a service as anything resembling a best practice. One solution I have found that works well is to use member sharing for similar functions.

For instance, if you are using the WCF service to perform mathematics on 2 values you might have 4 members on the service side: Add(x,y), Subtract(x,y), Multiply(x,y), Divide(x,y). If you combine these into a more generic member and use an object to pass the needed data you can easily reduce your member count and increase scalability. Example: PeformCalculation(obj) where obj has x, y, and action (add, subtract, multiply, divide) properties.

Hope this helps.

Answer 4

I found another solution to for this issue by using a the RoutingService class. Each contract must still be hosted in it's own ServiceHost, but there can be a RoutingService sitting on top of all of them - and presenting them over an unified "endpoint". I've also written a codeproject article about it. The example code is also available on Bitbucket.

Answer 5

chili's answer will work if you are ok with the contracts being shared by the service. If you want them to be separated try this:

host1 = new ServiceHost(typeof(MyService1));
host2 = new ServiceHost(typeof(MyService2));

host1.Open();
host2.Open();

public class MyService1 : IMyService1
{
    #region IMyService1
    #endregion
}

public class MyService2 : IMyService2
{
    #region IMyService2
    #endregion
}

Edit: As Matt posted, this would require multiple endpoints for each service/contract

Answer 6

No-one documented enpoints. Whe used more than one (as a group, from common url, for example http) must use the same binding instance (not more), i.e.

Your sample:

servicehost = new ServiceHost(typeof(MyService1));
servicehost.AddServiceEndpoint(typeof(IMyService1), new NetTcpBinding(), "net.tcp://127.0.0.1:800/MyApp/MyService1");
servicehost.AddServiceEndpoint(typeof(IMyService2), new NetTcpBinding(), "net.tcp://127.0.0.1:800/MyApp/MyService2");
servicehost.Open();

should be only one new Binding(), I tested over http.

servicehost = new ServiceHost(typeof(MyService1));
 BasicHttpBinding binding = new BasicHttpBinding();
servicehost.AddServiceEndpoint(typeof(IMyService1),binding , "http://127.0.0.1:800/MyApp/MyService1");
servicehost.AddServiceEndpoint(typeof(IMyService2), binding, "http://127.0.0.1:800/MyApp/MyService2");
servicehost.Open();

I agree totally with partial class implementing few contracts in few files.

Answer 7

What about splitting it up with a base address and multiple services/contracts below it? I am not behind a developmachine right now but something like:

http://myserver/myservices/serviceA
http://myserver/myservices/serviceB
http://myserver/myservices/serviceC

Each service implementing its own ServiceContract.

You can change
public class WcfEntryPoint : IMyService1, IMyService2
to
public partial class WcfEntryPoint : IMyService1
public partial class WcfEntryPoint : IMyService2

Example

Answer 8

Did I miss something, or is the simplest solution not mentioned here? The simplest solution is this: Don't use multiple interfaces for the Web Service.

But that doesn't mean you can still have your interfaces separated. This is why we have Interface inheritance.

[ServiceContract]
public interface IMetaSomeObjectService : ISomeObjectService1, ISomeObjectService2
{
}

The Meta interface inherits from all the other interfaces.

[ServiceContract]
public interface ISomeOjectService1
{
    [OperationContract]
    List<SomeOject> GetSomeObjects();
}

[ServiceContract]
public interface ISomeOjectService2
{
    [OperationContract]
    void DoSomethingElse();
}

Then the service just has the Meta interface.

public class SomeObjectService : IMetaSomeObjectService
{
   public List<SomeOject> GetSomeObjects()
   {
       // code here
   }

   public void DoSomethingElse()
   {
       // code here
   }
}