A web service composition model k2-MDD-WS

Web Service Dependency Graphs are the abstract model for the Web service composition that are facing great challenges in both increasing size and finite state search space. Compact representation and efficient operation of graph data are urgent topics, have been attracting more and more attentions. A Web service composition model based on multi-valued decision diagram, namely k2Multi-valued Decision Diagram of Web Service Dependency Graph (k2-MDD-WS), is proposed to reduce the storage space. The vertices of the Web Service Dependency Graph are encoded, and the edge codes are then encoded according to the codes of the vertices; so, the k2-MDD-WS is constructed based on the code sets of the edges. The k2- MDD-WS can combine redundant web service nodes caused by a large number of isomorphic sub-trees existing in the k2-tree to greatly reduce the number of nodes generated. Additionally, the operations of the Web Service Dependency Graph are transformed into Boolean operations under the k2-MDD-WS representation to further improve the efficiency of finding a Web service composition solution that meets user needs. The experimental results indicate that compression ratio in k2-MDD-WS is only 3.5%-7.5% of the in k2-tree. © 2020 Computer Society of the Republic of China. All rights reserved.