C# 2008 Programmer's Reference

service. The binding used determines the security requirements for the communication and how clients will connect to the service.

□ Contract — The contract defines what the service offers. The following sections discuss each of these points in detail.

Addresses and Endpoints

Every WCF service has an address and endpoints in which it listens for incoming connections. Figure 20-18 shows a WCF service with two endpoints exposed. A client wanting to use the service just needs to send messages to the appropriate endpoint.

Figure 20-18

The address of a WCF service depends on the protocols used for the service. For example, if a WCF service uses the HTTP protocol, then its address may be:

□ http://<server>:<port>/<service>

□ https://<server>:<port>/<service>

□ https://<server>:<port>/<service>.svc

If a WCF service uses TCP as the protocol, its address is in this format:

net.tcp://<server>:<port>/<service>.

For Named Pipes, the address is net.pipe://<server>/<service>.

A service may have an operation that uses any of the protocols (or all). For example, a service may listen at port 80 (endpoint number 1) using HTTP as well as listen at port 5000 (endpoint number 2) using TCP.

Bindings

The bindings of a WCF not only specify the protocols used but also the security requirements for communication. The following table describes the available bindings:

Binding	Description
BasicHttpBinding	Most basic; limited security and no transactional support. Compatible with traditional ASMX Web Services.
WSHttpBinding	More advanced HTTP with WSE security.
WSDualHttpBinding	Extends WSHttpBinding and includes duplex communications.
WSFederationHttpBinding	Extends WSHttpBinding and includes federation capabilities.
NetTcpBinding	Used for TCP communication; supports security, transaction, and so on.
NetNamedPipeBinding	Used for named pipe communication; supports security, transaction, and so on.
NetPeerTcpBinding	Supports broadcast communication.
MexHttpBinding	Publishes the metadata for the WCF service.
NetMsmqBinding	Used for MSMQ.
MsmqIntegrationBinding	Used for MSMQ.

The bindings of a WCF determine how a client can communicate with the service.

How to use BasicHttpBinding, WSHttpBinding, and NetTcpBinding bindings is shown later in this chapter.

Contracts

Contracts define what a WCF service offers. The types of available contracts are explained in the following table.

Contract	Defines
Service	All the operations contained in a service.
Operation	All the methods, parameters, return types, and so on.
Message	How messages are formatted. For instance, data should be included in SOAP header or SOAP message body, and so on.
Fault	Faults an operation may return.