A User Constraint Awareness Approach for QoS-Based Service Composition

Web service composition adopts functional features including the inputs and outputs, and non-functional features including quality of service (QoS), conditional structure constraints, user preferences, and trusts to compose homogeneous or heterogeneous services together in order to create value-added services. However, in some complex practical application scenarios, the web services with the same function can provide the generous differentiated contents, and there is no approach to focus on the user’s constraints on the content provided by the web services. In this paper, we focus on handling three composition dimensions simultaneously including functional features, QoS and the user’s constraints on the contents provided by the web services. Therefore, an improved genetic algorithm to obtain an optimal solution for this task is applied. In addition, we also take it into consideration that the over-constrained problem caused by implicit conflicting constraints and improve a constraint correction approach to solve this problem with less cost of consistency checks. Experimental results using the real datasets about travel demonstrate the effectiveness of our approach in creating the fully functional and quality-optimized solutions, on the premise that the users constraints on the content are satisfied.