Service-oriented computing is emerging as a new promising computing paradigm, that centers on the notion of service as the basic element for developing future distributed heterogeneous software applications.

The ability to aggregate separate services can allow a business entity to interact with a variety of service providers to re-brand, host, or offer a composition of services to its customers, as well as to reduce application development times and costs. The heterogeneous and evolving nature of Web services also calls for adaptation techniques to overcome various types of mismatches that may occur among services developed by different parties. Service adaptation provides a convenient way to integrate legacy systems, to ease the customisation of services to different types of clients, and to feature backward compatibility for service versions.

In this talk, we will describe a methodology for a disciplined aggregation and adaptation of Web services. A key ingredient of our approach is the notion of service contract, by means of which services self-describe their signature and behaviour. While the methodology relies on the YAWL workflow language to express service behaviour, it features the aggregation and adaptation of BPEL services by exploiting a suitable BPEL2YAWL translator.