Programming WCF Services, 2nd Edition

Metadata Exchange

By default, the service will not publish its metadata. However, this does not preclude clients that have obtained the metadata via some other mechanism from invoking operations on the service. A service that does not publish metadata is the WCF analogy to an internal class in .NET.

Publishing your service's metadata involves significant effort, since you have to convert CLR types and binding information into WSDL or some other low-level representation, and all that effort does not add any business value. But fortunately, the host already knows everything there is to know about your service and its endpoints, so it can publish the metadata for you if explicitly instructed to do so.

There are two options for publishing a service's metadata: you can provide the metadata over HTTP-GET, a simple text-based protocol that most platforms support, or you can use a dedicated endpoint (as discussed later).

WCF can provide the metadata for your service over HTTP-GET automatically; all you need to do is enable it by adding an explicit service behavior. Behaviors are described fully in subsequent chapters. For now, all you need to know is that a behavior is a local aspect of the service, such as whether or not it wants to have the host publish its metadata over HTTP-GET. You can add this behavior administratively or programmatically.

Enabling Metadata Exchange Administratively

Example 1-10 shows a host application config file, where both hosted services reference a custom behavior ...