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Figure 25-5. System.Runtime.Serialization defines a number of attributes used when building WCF

data contracts.

Understanding WCF Bindings

Once a contract (or a set of contracts) has been defined and implemented within your service

library, the next logical step is to build a hosting agent for the WCF service itself. As mentioned, you

have a variety of possible hosts to choose from, all of which must specify the 

bindings used by

remote callers to gain access to the service type’s functionality.

Choosing a set of bindings is one area that makes WCF development quite different from .NET

remoting and/or XML web service development in that WCF ships with a number of binding

choices, each of which is tailored to a specific need. If none of the out-of-the-box bindings fits the

bill, it is possible to create your own by extending the CustomBinding type (something we will not do

in this chapter). Simply put, a WCF binding can specify the following characteristics:

• The contracts implemented by the service

• The transport layer used to move data (HTTP, MSMQ, named pipes, TCP) 

• The channels used by the transport (one-way, request-reply, duplex)

• The encoding mechanism used to deal with the data itself (XML, binary, etc.)

• Any supported web service protocols (if permitted by the binding) such as WS-Security, WS-

Transactions, WS-Reliability, and so on

Let’s take a look at our choices.

HTTP-Based Bindings

The BasicHttpBinding, WSHttpBinding, WSDualHttpBinding, and WSFederationHttpBinding options

are geared toward exposing contract types via XML web service protocols. Clearly, if you require the

furthest reach possible for your service (multiple operating systems and multiple programming

architectures), these are the bindings to focus on, because all of these binding types encode data

based on XML representation and use HTTP on the wire. 

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