QoS-aware Web Service Composition Based On Blockchain Smart Contract

A web service composition is aimed at building a distributed application by assembling the exists web services.However,with the rapid growth of web services,which have the same functionality but differ in QoS,it is difficult for users to find the suitable services to assemble.Existing solutions require the support of a third-party platform,and have flaws such as easy to fall into a local optimum and slow convergence at the later stage.Therefore,this dissertation proposes a QoS-aware Web service composition method based on blockchain smart contracts.First of all,this method is combined with blockchain technology to design the overall architecture based on the Ethereum platform,which building a safe and reliable transaction environment for users and service providers.By calling the smart contract,the system automatically executes the core algorithm of the Web service composition,and stores each transaction on the blockchain.Once the transaction is stored on the blockchain,no party involved in the transaction can be violated,thereby eliminating the restrictions of third-party platforms.Secondly,this dissertation uses an improved multi-objective grey wolf optimization algorithm as the core algorithm of the Web service composition.By adopting the convergence factor based on the variation of cosine law and boltzmann selection strategy,the exploration stage and the exploitation stage are balanced,thereby improving the flaws of the traditional method.Finally,in order to verify the feasibility of the proposed method,this dissertation uses five representative functions in the multi-objective benchmark functions CEC2009 and ZDT,meanwhile uses the QWS benchmark dataset for evaluation,and compares it with the four representative algorithms.The result shows that the method proposed in this dissertation doesn't need third-party platforms and more reliable and safer,which has obvious improvement in the precision of optimization and the quality of the solution.Moreover,it also can obtain a better composition when solving the problem of web service composition.