Design And Implementation Of A Middleware System Supporting Dynamic Component Updates

Software applications often need updates to fix bugs or address changes in their execution environments and the user requirements. The traditional way to update a software system is to stop the system, replace it with a new version, then restart it. However, this method is not acceptable for mission critical systems that must be non-stopping. In this situation we need to use dynamic software update (DSU), which changes (a part of) a software system at runtime without stopping it.This thesis presents a middleware-based solution for DSU. Middleware systems are widely used as their convenient programming abstractions and powerful runtime services facilitate the development, deployment and execution of distributed business applications. However, existing middleware systems provide limited supports for DSU, especially they cannot ensure system consistency during and after system update. To address this problem, we have designed and implemented a middleware system with comprehensive dynamic component update support. We have also extensively evalu-ated the middleware system with a third-party application system. The results exhibits its flexibility of using different consistency ensuring algorithms and its advantages in update timeliness and disruption to application execution.The work can be summarized as follows:1. After analyzing the deficiencies of existing middleware systems’support for DSU, we present a systematic solution for middleware supporting dynamic com-ponent update. The solution includes component lifecycle management, trans-action lifecycle management, dynamic dependences management and dynamic update interface. 2. Based on the solution, we have designed and implemented the ConUp middle-ware system on top of Apache Tuscany. ConUp supports the deployment, man-agement and online evolution of components. It also provides different dynamic update algorithms and strategies to ensure application systems’safety and effi-ciency during and after dynamic updating.3. We have chosen a sample applications system provided by Apache Tuscany as a case study to evaluate the performance of ConUp. The focus has been put on the following aspects:safety, timeliness, disruption and overhead. Last but not least, we have also studied the effect of granularity on dynamic update process.