摘要:微服务设计模式通过将应用程序拆分成多个相互独立的微服务，实现了各个微服务之间的相互解耦，允许各个微服务能够独立地进行迭代开发、部署，从而对用户需求变化以及DevOps流程中部署需求作出快速响应.每个微服务的独立迭代升级导致了系统中可能出现多版本共存现象，不同服务的不同版本之间的依赖关系变得更加复杂.如何在这种场景下适应用户不断变化的需求以及开发者敏捷DevOps流程中部署需求，是当前面临的一个挑战.为解决这一问题，提出了微服务依赖模型来刻画不同服务的不同版本之间复杂的依赖关系，设计了基于贪婪的优化算法来找到最优的微服务系统演化方案，以满足用户需求变化和敏捷DevOps流程中部署需求，并实现了面向演化的微服务编程框架（MF4MS）和微服务系统自适应架构（MI4MS），可支持演化方案的自动执行，实现微服务系统运行时的自适应演化.实验结果表明：在有着复杂依赖的微服务系统中，该方法在服务失效时长、服务可用性、开发者DevOps代价等指标上有很好的表现，可有效支持微服务系统自适应演化，以应对用户需求变化和敏捷DevOps.



Abstract:A microservice-based system is composed of a set of microservices that are developed and deployed independently for agile DevOps. Intensive and iterative adaptations/upgrades of microservices are essential for such systems to adapt to user requirement changes and DevOps, and as a consequence, result in the phenomenon of "multi-version microservice coexistence" in a system. Besides traditional API-based functional dependencies between different microservices, there appear complicated dependencies between different versions of difference microservices, which dramatically deteriorate the maintainability of microservice systems, especially when systems evolve to adapt to user requirement changes and DevOps. To meet this challenge, a version dependency model is proposed for describing the complex dependencies between different versions of microservices, and greedy-based optimization algorithms are developed for generating an optimal evolution plan according to changes in user requirements and DevOps at different scenarios. A programming framework (MF4MS) and cloud-edge based infrastructure (MI4MS) are implemented to facilitate microservice systems to automatically execute the evolution plan. Experiments show that the proposed approach performs well on service down time, service availability, and the developers' cost of DevOps coping with self-adaptation in the situation where complicated version dependencies exist.



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