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Web services generalize the idea of the Web beyond the exchange of simple Web
pages in order to enable the provision of a broad range of different services. By com-
posing Web services, cross-organizational and collaborative business processes can
be realized in a highly dynamic and flexible way, which is particularly important if
services have to be automatically procured at runtime. However, achieving a higher
degree of automation is obstructed by the informal nature of legal, contractual and
organizational regulations, the numerous and complex service descriptions includ-
ing manifold customization possibilities, and the open and heterogeneous nature of
the Web service market.
In this thesis, semantic technologies that provide more explicit meaning of in-
formation are employed to address these problems. These technologies facilitate
the exchange of information in heterogeneous systems and increase the share of
machine-understandable data accessible for automated decision-making. We intro-
duce the Core Policy Ontology in order to capture regulations as well as preferences
by means of goal and utility function policies, respectively. Furthermore, we in-
troduce the Core Ontology of Bids that facilitates customization of Web services to
specific user needs by efficiently representing highly configurable Web service of-
fers and requests. Analogously, we derive the Core Contract Ontology from the
Core Policy Ontology to formally represent Web service contracts. Thereby, we pro-
vide an open, transparent and interoperable representation of contracts and enable
a tight integration of contractual information with the collaborative business inter-
actions they govern. |