Given their lack of formally described interfaces and the possibility
of not always using XML messages, RESTful Web services
are cumbersome to compose using the WSDL-based invocation
abstractions provided by WS-BPEL [30]. The composition
of RESTful Web services is the main focus of so-called Web 2.0
Mashups, which are seen as a welcome improvement over screenscraping
the information to be composed out of traditional HTML
Web sites