Thomas Fielding famous dissertation about REST (Representational State Transfer) has giving rise to a grass roots movement, which competes head-to-head with SOAP/WSDL-based Web Services. The two concepts are really very different. SOAP/WSDL is operation driven, where data is exchanged according to the operation (method) invoked. There are many operations and few endpoint addresses (URLs). REST, on the other hand, is URI driven, where data is exchanged according to its address and only a few standard methods are offered (GET, POST, PUT, DELETE). In addition to Thomas Fielding’s dissertation you can also read a couple articles by Paul Prescod which summarize the concepts nicely: Second Generation Web Services and REST and the Real World.