Dynamic web service composition using AND/OR directed graph
Hajar Elmaghraoui, Laïla Benhlima, Dalila Chiadmi · 2017
Because of their interesting properties, web services have grown in popularity and have become the preferred technology for distributed systems development. It is then necessary to find efficient solutions for web service composition that can deal with large amounts of services. However, in order to coordinate the exchanges of the data flow in a combination of services, different control structures can contribute, which will complicate the search for an optimal composition. Moreover, the time constraints as well as the increasing number of services also complicate the problem of the composition. In this paper, we presents a formalization of the web Service composition problem as a search problem in an AND/OR Service Dependency Graph, where nodes represent available services and arcs represent the semantic input/output dependencies among them. A set of dynamic optimization techniques have been included to reduce the size of this graph and thus improve the scalability and performance of our approach. We pre-compute all the shortest paths between each pair of this graph's nodes using a graph search algorithm. These paths will be used upon the receipt of a client request, and this reduces the running cost. Furthermore, our model is not only capable of dealing with sequence relations and fork relations, but also capable of dealing with parallel relations between services.