In the past I've talked a lot about the absolute minimum you need to do to write a working channel. However, what about the people that want all of the optional bells and whistles that can go along with channel development? There are several interfaces that you can implement on the binding element or in your custom channel solution to add functionality. I'm not going to go over these interfaces in detail today, but I did want to at least catalog the interfaces that are available.

The base class for a channel binding element is taken up by the fact that you have to subclass BindingElement or TransportBindingElement. Therefore, the optional functionality is generally provided through interfaces that you can add to the binding element or on separate objects.

  • WS-Policy export. The IPolicyExportExtension interface lets you define an ExportPolicy method that overrides the policy construction process.
  • Metadata export. The IWsdlExportExtension interface lets you define an ExportContract and an ExportEndpoint method that override the metadata construction process.
  • WS-Policy import. The IPolicyImportExtension interface has the reverse method ImportPolicy to consume policy statements.
  • Metadata import. The IWsdlImportExtension interface has the reverse methods ImportContract and ImportEndpoint to consume metadata. IWsdlImportExtension also has a method called BeforeImport. Metadata consumption is done using a multi-phase process, where all of the importers get to look at the metadata once before actually doing the work.
  • Configuration import and export. Configuration on the binding element is added by subclassing BindingElementExtensionElement. This is a separate object that has to parallel all of the settable properties on the binding element.
  • Binding configuration import and export. If you put your binding element into a standard binding, then you can provide configuration for that binding as well. You need two separate objects subclassing StandardBindingElement and StandardBindingCollectionElement.

Next time: Messaging is not a Transaction