Algorithms for semi-automatic Web service composition
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This dissertation presents a semi-automatic Web service composition approach, which works by ranking all the candidate Web service operations and suggesting service operations to a human designer during the process of Web service composition. The ranking scores are determined by computing sub-scores related to inputs/outputs, data mediation, functionality and precondition/effects. A formal graph model, namely IODAG, is defined to formalize an input/output schema of a Web service operation. Three data mediation algorithms are developed to handle the data heterogeneities arising during Web service composition. The data mediation algorithms analyze the schema of the input/output of service operations and consider the structure of the schema. Typed representations for the data mediation algorithms are presented, which formalize the data mediation problem as a subtype-checking problem. An evaluation is performed to study the effectiveness of different data mediation and service suggestion algorithms as well as the effectiveness of semantic annotations used to assist human designers composing Web services.