Web Services for Interoperable Management (Continued)

On WebLogic Server, you specify handlers in the Web application's web-services.xml file. Specify a handler-chains element under the root web-services element:

<handler-chains>
  <handler-chain name="TraceHandlerChain">
    <handler class-name="test.TraceHandler" />
  </handler-chain>
</handler-chains>

Also, for each Web service method on which you want to use the handler chain, you need to specify a handler chain by name using a handler-chain attribute on an operation element. For more details, locate some sample web-services.xml files in a WebLogic Server install.

Micro-Managing
On the .NET Framework side, you can implement the abstract System.Web.Services.Protocols.SoapExtension class to inspect or modify the SOAP message during processing.

When you extend SoapExtension, you must implement the ProcessMessage() method:

public abstract void 
   ProcessMessage(SoapMessage message);

The SoapMessage parameter can be of type SoapClientMessage or SoapServerMessage.

The method is called at any of four SOAP message-processing stages, as specified by the members of the SoapMessageStage enum: BeforeDeserialize, AfterDeserialize, BeforeSerialize, and AfterSerialize. The SoapMessageStage.AfterSerialize and SoapMessageStage.BeforeDeserialize values give access to the stream sent over the wire. Your ProcessMessage() implementation should check the stage using the SoapMessage object's Stage property. (For finer prioritizing, override the ChainStream() method.)

Once you've derived a class from SoapExtension, you can indicate when it's run in two ways:

• Specify the SOAP extension with an add element under the soapExtensionTypes element in an applicable configuration file (typically Web.config). This runs it with all Web services in the config file's scope.
• Define a class that implements the abstract SoapExtensionAttribute class. That means implementing the ExtensionType property to return the type of the SoapExtension. Then apply the attribute to a Web service method or client proxy class method.

Web Services for More Than Web Services
Go back to the concept of agents and managers exposing Web service interfaces to each other. That's what SIFT does, allowing its own manager, SIFT Console, to provide a unified management view of both ASP.NET and J2EE Web services.

Now take the next logical step and swap out the thing being managed. The agent and manager can still act as an interchangeable Web service and client to each other, but now the content they're managing isn't only Web services, but potentially the whole IT infrastructure.

For managing sundry aspects of its server systems, Microsoft offers the Microsoft Operations Manager (MOM) 2000 application. Last fall, Microsoft introduced the MOM Connector Framework (MCF), which, for one thing, exposes MOM 2000 as a Web service (see Resources). At the same time, Microsoft and other software vendors announced the availability of "product connectors" to reconcile the MOM/MCF API with the APIs of those vendors' management tools. Result: MOM 2000 can do two-way alerts with other management systems.