The coordinated recovery of data service and transaction service in J2EE

Middleware can be viewed as a collection of common services which may fail caused by various reasons. Recovery-based fault tolerance is an effective way to improve middleware services´ dependability. But the interdependent relationships among services make the recovery of failed services complex. This paper analyzes the interdependent relationships and correlated faults of the data service and the transaction service in J2EE (Java 2 Platform Enterprise Edition), and presents the coordinated recovery of these two services, which is demonstrated in PKUAS, a J2EE-compliant middleware product. Our coordinated recovery uses a configuration file to define correlated faults and their corresponding recovery operations, a centralized coordinator to schedule these operations, and the request caching to improve the effect. Experimentation results show that our coordinated recovery provide a better user-visible availability than other recovery strategies.