Service Architectures (SOA's) are often delimited to the confines of the server-side, but adopting this same paradigm in mobile devices can have an equally important impact. Eric Giguere explores SOA without SOAP in the context of Java ME.
While it's true that the Web Services APIs for Java ME (WSA) support a subset of the SOAP 1.1 standard and a simple API for parsing XML, WSA support is far from widespread. (See Understanding the Web Services Subset API for Java ME for an introduction to WSA.) The pragmatic Java ME developer understands this, which is why alternative approaches must often be explored. And even if SOAP was universally supported on Java ME platforms, some developers would look for different solutions because of the extra overhead involved in using SOAP. (If SOAP is required and WSA is not available, the kSOAP 2 open source SOAP library is an option to consider.)
Read Eric's post: http://developers.sun.com/mobility/midp/ttips/soanosoap/