Programming WCF Services

Operations and Calls

1. Do not treat one-way calls as asynchronous calls.

2. Do not treat one-way calls as concurrent calls.

3. Expect exceptions out of a one-way operation.

4. Enable reliability even on one-way calls. Use of ordered delivery is optional for one-way calls.

5. Avoid one-way operations on a sessionful service. If used, make it the terminating operation:

   [ServiceContract(SessionMode = SessionMode.Required)]
   interface IOrderManager
   {
      [OperationContract]
      void SetCustomerId(int customerId);
   
      [OperationContract(IsInitiating = false)]
      void AddItem(int itemId);
   
      [OperationContract(IsInitiating = false)]
      decimal GetTotal( );
   
      [OperationContract(IsOneWay = true,IsInitiating = false,IsTerminating =
   true)]
      void ProcessOrders( );
   }

6. Name the callback contract on the service side after the service contract suffixed by Callback:

   interface IMyContractCallback
   {...}
   [ServiceContract(CallbackContract = typeof(IMyContractCallback))]
   interface IMyContract
   {...}

7. Strive to mark callback operations as one-way.

8. Use callback contracts for callbacks only.

9. Avoid mixing regular callbacks and events on the same callback contract.

10. Event operations should be well-designed:

    1. void return type

    2. No out parameters

    3. Marked as one-way operations

11. Avoid using raw callback contracts for event management, and prefer using the publish-subscribe framework.

12. Always provide explicit methods for callback setup and teardown:

    [ServiceContract(CallbackContract = typeof(IMyContractCallback))] interface IMyContract { [OperationContract] void DoSomething( ...