基于区块链机制的云计算环境下服务组合策略的研究

Research on service composition strategy based on block chain mechanism in cloud computing environment

云计算环境下服务组合具有规模大、复杂性高、失效类型多以及资源动态变化等特征,因此安全、可信的服务组合方案是云环境下海量服务资源灵活部署、按需提供的最大挑战。对区块链共识机制、智能合约及可编程特征进行深入分析,类比服务组合特征与流程,基于服务层次覆盖网络(service overlay networks,SON)理论提出一种可信度和可靠性更为突出的以区块链为底层基础设施的服务组合体系架构;考虑区块链共识机制带来的安全策略,借鉴智能合约的功能与作用,提出了跨服务覆盖层的基于链路预测生存时间及服务强度最优策略的高效服务路径生成算法;设计了带有单点信任度及交互紧密度指标的可信服务质量模型(trust of service,To S),以及该To S驱动下的服务路径选择算法。仿真结果表明,基于区块链机制的服务组合实现策略大大提升了组合服务执行的成功率及可用性。

As the features of service composition such as large scale,high complexity,various failures and resource dynamics,a safe and credible service composition scheme is one of the biggest challenges for flexible deployment and on-demand providing. Based on the critical analysis of block chain infrastructure,consensus mechanism and programmable features,contrasting to the characteristics and process of Web service composition,this paper developed an novel service composition system architecture with much more credibility and reliability using service overlay networks theory. In addition,considering the security strategies derived from block chain consensus mechanism,and making full use of smart contract’s functions and effects,this paper proposed an effective algorithm based on the predictive route life time( RLT) and service intensity( SI)across overlay networks for the generation of service paths. Besides,it designed a better service-path selection algorithm which was decided by the trusted quality of service model with the single-node’s trust index and interactive tightness index. The simulation results show that the service composition strategy based on block chain mechanism has greatly increased the success rate and credibility of service components after composition.