WCF Web Method that Accepts Different Message Types

Question

Microsofts's WCF is easy to work with when you create Web services where each message has it's own Web method. WCF generates all of the WSDL and everything is easy.

What I want to do is have one Web method that accepts multiple different messages (I don't want to add a mew method every time I add a new message type). The messages themselves will have header information that identify the message type. Once I know the message type, I'll know the structure of the rest of the message.

The only way I've found to do this with WCF is to have the method accept a string, which I parse in as XML and and use. However, I can see no clear way to publish the various message types in the WSDL; so, the whole service is essentially undocumented.

Anyone know of a technique to use in WCF?

Answer 1

You can write an operation contract that accepts any message by setting the Action to * and having it take in a Message object:

[ServiceContract]
public interface IMessageContract
{
    [OperationContract(Action = "*", ReplyAction = "*")]
    Message ProcessRequest(Message request);
}

The Message object gives you access to the headers and has methods to deserialize the body.

To export your own WSDL, you will need to implement IWsdlExportExtension on a contract behavior or operation behavior and attach it to your service. This will give you access to a WsdlExporter, and you can create a ContractDescription yourself and call ExportContract to have it appear in the generated WSDL.