Implementing Service Contracts

A service is a class that exposes functionality available to clients at one or more endpoints. To create a service, write a class that implements a Windows Communication Foundation (WCF) contract. You can do this in one of two ways. You can define the contract separately as an interface and then create a class that implements that interface. Alternatively, you can create the class and contract directly by placing the ServiceContractAttribute attribute on the class itself and the OperationContractAttribute attribute on the methods available to the clients of the service.

The following is an example of a service that implements an IMath contract that has been defined separately.

// Define the IMath contract.  
[ServiceContract]  
public interface IMath  
{  
    [OperationContract]
    double Add(double A, double B);  
  
    [OperationContract]  
    double Multiply (double A, double B);  
}  
  
// Implement the IMath contract in the MathService class.  
public class MathService : IMath  
{  
    public double Add (double A, double B) { return A + B; }  
    public double Multiply (double A, double B) { return A * B; }  
}  

Alternatively, a service can expose a contract directly. The following is an example of a service class that defines and implements a MathService contract.

// Define the MathService contract directly on the service class.  
[ServiceContract]  
class MathService  
{  
    [OperationContract]  
    public double Add(double A, double B) { return A + B; }  
    [OperationContract]  
    private double Multiply (double A, double B) { return A * B; }  
}  

Note that the preceding services expose different contracts because the contract names are different. In the first case, the exposed contract is named "IMath" while in the second case the contract is named "MathService".

You can set a few things at the service and operation implementation levels, such as concurrency and instancing. For more information, see Designing and Implementing Services.

After implementing a service contract, you must create one or more endpoints for the service. For more information, see Endpoint Creation Overview. For more information about how to run a service, see Hosting Services.

• Designing and Implementing Services
• How to: Create a Service with a Contract Class
• How to: Create a Service with a Contract Interface
• Specifying Service Run-Time Behavior