Requirements Analysis
SOAP
SOAP Encoding
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Mapping to HTTP

The mapping to HTTP covers both the RPC mechanism, and the extensions to this protocol. A method call is specified by an XML element--parameters being child elements. A method call response element bears the same name as the call element, with the added Response suffix. Method calls and call responses are mapped respectively to HTTP POST requests and HTTP POST responses. A last important consideration is the adjunction of the SOAPAction field to the HTTP request header--which identifies the target service on the remote host. The SOAP message exchange model does not define an object brokering architecture, but a simpler RPC model that specifically does not support distributed garbage collection. By way of consequence, it does neither define passing object references nor object activation (which requires the ability to pass objects by reference).
These design decisions were taken on the grounds of both simplicity and flexibility. Needless to say that this project would not have been feasable otherwise.

The purpose of this chapter was to introduce the reader to the realm ot this project. We first presented the inception of the Web service paradigm, which will be further developed in the first part of Chapter . We then outlined some more pragmatic aspects of this project, related to the engineering of the framework prototype. The last section was given as a compendium to the respective formal documents from the W3C--capturing only the items of direct relevance to this project. The reader is referred to Chapter and the documents themselves (, ,,; Box et al., 2000; , ) for a detailed coverage of the subjects.