23 May 2012

Endpoints: Addresses, Bindings, and Contracts in WCF


Endpoints: Addresses, Bindings, and Contracts in WCF

All communication with a Windows Communication Foundation (WCF) service occurs through the endpoints of the service. Endpoints provide clients access to the functionality offered by a WCF service.

Each endpoint consists of four properties:
  • An address that indicates where the endpoint can be found.
  • A binding that specifies how a client can communicate with the endpoint.
  • A contract that identifies the operations available.
  • A set of behaviors that specify local implementation details of the endpoint. 

The Structure of an Endpoint

Each endpoint consists of the following:
  • Address: The address uniquely identifies the endpoint and tells potential consumers of the service where it is located. It is represented in the WCF object model by theEndpointAddress class. An EndpointAddress class contains:

    • Uri property, which represents the address of the service.
    • An Identity property, which represents the security identity of the service and a collection of optional message headers. The optional message headers are used to provide additional and more detailed addressing information to identify or interact with the endpoint.
    For more information, see Specifying an Endpoint Address.
  • Binding: The binding specifies how to communicate with the endpoint. This includes:

    • The transport protocol to use (for example, TCP or HTTP).
    • The encoding to use for the messages (for example, text or binary).
    • The necessary security requirements (for example, SSL or SOAP message security).
    For more information, see Windows Communication Foundation Bindings Overview. A binding is represented in the WCF object model by the abstract base class Binding. For most scenarios, users can use one of the system-provided bindings. For more information, see System-Provided Bindings.
  • Contracts: The contract outlines what functionality the endpoint exposes to the client. A contract specifies:

    • What operations can be called by a client.
    • The form of the message.
    • The type of input parameters or data required to call the operation.
    • What type of processing or response message the client can expect.
    For more information about defining a contract, see Designing Service Contracts.
  • Behaviors: You can use endpoint behaviors to customize the local behavior of the service endpoint. Endpoint behaviors achieve this by participating in the process of building a WCF runtime. An example of an endpoint behavior is the ListenUri property, which allows you to specify a different listening address than the SOAP or Web Services Description Language (WSDL) address. For more information, see ClientViaBehavior.

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