Learning WCF

WCF Contracts and Serialization

So far I’ve talked about the standards behind it all, but in fact WCF hides most of this from the developer by providing a programming interface for designing service contracts and controlling the message format. Application messaging requirements are described by contracts in WCF. There are three types of formal contracts that clients and services rely on to control messaging. The service contract describes the operations exposed by a particular service endpoint. Each operation, through parameters and return types, defines the format of request and response messages. A data contract describes how a complex type is serialized as part of a message. Data contracts are the preferred way to include complex types in a service contract. A message contract provides control over the format of the entire SOAP message, including support for custom message headers and individual body elements that can be described by data contracts.

By default, message serialization is handled by the DataContractSerializer. This is a new serializer introduced with WCF that requires all types to opt-in their exact requirements for serialization—in compliance with SOA tenets. The DataContractSerializer can serialize data contracts, message contracts, and other serializable types such as those marked with the SerializableAttribute or those that inherit IXmlSerializable (see Figure 2-2). It is also possible to tell WCF to use the XmlSerializer that ASP.NET web services use (useful ...