A Dynamic Web Service Composition Algorithm Based on TOPSIS

Multi-period QoS evaluations have to be considered for obtaining a reliable decision in the service selection process. Besides, open and dynamic Internet environment increased the uncertainty of decision-making. To solve the above difficulties, this paper presents a novel hybrid data type (including real numbers, interval numbers, triangular fuzzy numbers and intuitionistic fuzzy numbers) QoS model, multi-period hybrid QoS aggregating operator and a strategy for aggregating composition service QoS firstly. Furthermore, a dynamic Web service composition algorithm based on TOPSIS (DWSCA_TOPSIS) is presented to evaluate multi-period hybrid QoS data. DWSCA_TOPSIS includes four main steps: converting hybrid QoS into intervals, calculating weighted normalized decision-matrix, determining the positive-ideal and negative-ideal solution, calculating the close-degrees of candidates. Finally, some experiments are given using actual QoS data to demonstrate the benefits and effectiveness of our approach.