Java Web Services in a Nutshell

SOAP Messages

The format of SOAP messages is defined by a note submitted to the World Wide Web Consortium (W3C) in May 2000 by a group of companies including Microsoft and IBM. This note, which describes Version 1.1 of SOAP and can be downloaded from http://www.w3.org/TR/SOAP, is not a formally adopted W3C specification but it is, nevertheless, the specification on which all existing SOAP implementations, including SAAJ, are based. The W3C is working on a formal definition of the next revision of SOAP, to be called Version 1.2. At the time of this writing, the SOAP 1.2 specification is available for public review, and Sun plans to include support for SOAP 1.2 in SAAJ (and JAX-RPC) when the specification is finalized.^[26]

SOAP defines a way to wrap information represented in XML so that it can be transmitted between peer entities that know how to interpret that information and, presumably, act on it to provide a service. Other than the fact that the useful content of the message (which is known as the payload) must be encoded in XML, SOAP does not mandate a particular set of XML elements and attributes to be used to represent primitive items of data (such as integers, floating-point numbers, and strings) in terms of XML constructs, although it does specify an encoding mechanism for these data types and others, the use of which is encouraged. In practice, these encoding rules, commonly referred to as “SOAP section 5 encoding,” have become a de facto standard and are the default encoding ...