In Chapter 1, we provided an overview of the Web services technology stack. Subsequent chapters on SOAP, WSDL, and UDDI covered the standard (or de facto standard) technologies and specifications for the service messaging, service description, and service registration layers of the stack. For service security and service transactions layers, consensuses on standards are emerging and those standards were explained in the chapters on security and transactions, respectively. Other areas of the stack either lack standard specifications or have competing standards sponsored by different industry groups. In this chapter, we discuss a few specifications that are possible future standards for Web services.
In Chapter 5, we explained that there are different forms of service definition. WSDL is the specification that details how to describe a Web service's functional interface . It does not cover how the service can be composed into larger applications. Two emerging (and competing) specifications describe the mechanics of service composition: WSCI and BPEL4WS. We will introduce these two specifications in this chapter.
In Chapter 4, we explained that SOAP provides the foundation for Web service messaging and that the SOAP processing model's extensibility features permit more complex message exchange patterns. WS-Routing is a specification that exploits this SOAP feature and proposes the use of standardized SOAP headers to set the path of a SOAP message. We examine WS-Routing and its application in this chapter as well.
In the last section of this chapter, we briefly discuss two JSRs that will have a significant effect on Web services on the Java platform. JSR-181 proposes meta-data meant to ease development and deployment of Web services on the J2EE platform. JSR-172 proposes an API for processing XML and conducting XML RPC from J2ME clients.