Windows Communication Foundation (WCF) provides numerous extensibility points that allow developers to customize the runtime behavior for service dispatching and client proxy invocation. You can tap into these extensibility points by writing custom behaviors that can be applied declaratively to your services.  For example, you can customize the way an endpoint serializes data, or user credentials used when sending a message.  Behaviors do not manifest themselves in published metadata or a binding for a service, and they do not affect the communication process.  You can apply them to the service itself or to specific endpoints, contracts, and operations.  You can also customize a behavior using a behavior extension. 

To use a custom behavior extension in Windows Server AppFabric, you will need to configure it correctly using  Microsoft Web Administration (MWA) . The classes in the Microsoft.Web.Administration namespace contain a series of convenient top-level objects that allow the developer to perform administrative tasks. With the classes in this namespace, an administrator can read and write configuration information to ApplicationHost.config, Web.config, and Administration.config files.  MWA requires that all the configuration elements be schematized.

For information on how to create a schema for your custom behaviors to use with AppFabric, see