Modelling of service compositions: Relations to business process and workflow modelling

The service oriented architecture (SOA) represents a trend in the IT industry for the development of a flexible and unifying software infrastructure. In an SOA, software components provide their functionality as a service by using uniform interface description and invocation protocols. The provision of software components in an uniform manner allow their efficient composition to form new complex services. Currently, the compositions of services is a popular field of research with many ongoing efforts. However, the sheer number of existing proposals and efforts to describe service compositions in this field have led to term Web Services Acronym Hell (WSAH) [1] and an obvious confusion. This paper intends to serve as an orientation for explaining what the differences between business processes and workflow control flow languages are and why service compositions are used in this field. It will also introduce past and existing proposals for Web service composition languages for understanding why so many different languages for modelling workflows, business processes and compositions exist.