The Dagstuhl Seminar on Autonomous and Adaptive Web Services brought researchers together whose current research interests are centered around web services composition and adaption.

Web Services provide the universal basis for the integration of networked applications and business processes that are distributed among the most disparate entities, both within and across organizational borders. The fundamental idea of Web Services is that applications are built by interacting with and composing external components -- services -- that are available on the Web, and that are not under the control of a single party or stakeholder. A new challenge arises from this idea: the success of service oriented applications is unavoidably depending on the capability of a service to autonomously adapt to an environment that is not fully under control. Therefore a need exists for techniques that enable the flexible composition and adaption of web services.

The participants of the seminar discussed to which extent a fully automatic composition and self-adaptation of web services is possible and which prerequisites have to be fulfilled in order to enable such a high degree of autonomy. Two main technologies were reflected in the presentations: First, approaches to the semantic web that improve the precise semantic descriptions of web services played an important role in the discussion. The resulting semantic web services and their role in service-oriented architectures were discussed by several participants.

Second, formal analysis and verification techniques that provide the foundation for composition and adaptation algorithms that sometimes made use of semantic web services were presented. Petri net techniques, model checking and process calculi were discussed in detail and their opportunities and limitations explored.

A tools session offered interesting insights into the capabilities of various tools and allowed participants to compare and position their approaches in detail.

The seminar showed that web services, semantic web, and service composition and adaption are quickly moving areas at the moments. Progress in the various areas enables novel solutions to be built that enable fascinating applications.

Our gratitude goes to the scientific directorate of Schloss Dagstuhl for giving us the possibility of organizing this workshop. Andreas Schroeder collected the abstracts and carefully edited this report. Moreover, the workshop would not have been possible without the help of the friendly and efficient staff of Schloss Dagstuhl. Our sincere thanks go to all of them.