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Service Types As Operational Contracts

Finally, recall that the use of interfaces is not required when building WCF service types. It is in fact

possible to apply the [ServiceContract] and [OperationContract] attributes directly on the service

type itself:

// This is only for illustrative purposes

// and not used for the current example.

[ServiceContract(Namespace = "http://Intertech.com")]

public class ServiceTypeAsContract

{

[OperationContract]

void SomeMethod() { }

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---

[OperationContract]

void AnotherMethod() { }

}

Although this approach is possible, there are many benefits to explicitly defining an interface

type to represent the service contract. The most obvious benefit is that a given interface can be

applied to multiple service types (authored in a variety of languages and architectures) to achieve a

high degree of polymorphism. Another benefit is that a service contract interface can be used as the

basis of new contracts (via interface inheritance), without having to carry any implementation bag-

gage. 

In any case, at this point our first WCF service library is complete. Compile your project to

ensure you do not have any typos.