J2EE Meets Web Services

摘要

According to the stencil group, a san francisco-based consulting and advisory firm, Web services can be genetically defined as "... loosely coupled, reusable software components that semantically encapsulate discrete functionality and are distributed and programmatically accessible over standard Internet protocols." A Web service can be more specifically defined as a piece of software that can be referred to by a Uniform Resource Identifier (URI) and that uses XML to detail its contracts or interfaces and bindings. Other pieces of software can then look up a Web service using these details and exchange messages with it over standard Internet protocols. Per the Web Services Architecture Working Draft 2002 with the W3C, the Web services architecture can be depicted as a layered collection or stack of components and technologies called the Basic Web Services Architecture. This architecture covers message exchange between roles, Web services details or descriptions, and the lookup of Web service details. As shown in Figure 1, the Basic Web Services Architecture models the collaborations between the Service Provider, the Service Discovery Agent and the Service Requestor.