Implicit vs. explicit data-flow requirements in Web service composition goals

In this paper we compare two different approaches to specify data-flow requirements in Web service composition problems, i.e., requirements on data that are exchanged among component services. Implicit data-flow requirements are a set of rules that specify how the functions computed by the component services are to be combined by the composite service. They implicitly define the required constraints among exchanged data. Explicit data-flow requirements are a set of explicit specifications on how the composition should manipulate messages and route them from/to components. In the paper, we compare these two approaches through an experimental evaluation, both from the point of view of efficiency and scalability and from that of practical usability.