REST vs. SOAP

REST seeks to maximally leverage HTTP to give programs access to web content, and is usually set in contrast to SOAP-based web services, which just tunnel remote procedure call style services inside HTTP requests and responses.

http://stackoverflow.com/a/1077489/2066936

Workflow Defined

Workflow is the general way of linking services together

 http://www.nesc.ac.uk/technical_papers/UKeS-2004-05.pdf