Scalability Evaluation of the Replication Support of JOnAS, an Industrial J2EE Application Server

Today most web applications are deployed on multi-tier architectures, such as those based on J2EE. These applications need to be highly available and scalable. Replication is used to achieve these properties. Most J2EE application servers provide some form of replication. This paper reports on the performance evaluation of the replication protocol included in the JOnAS J2EE application server. The protocol attains high availability in the middle tier in an affordable manner and guarantees consistency across tiers and exactly-once semantics in the advent of failures. The evaluation has been performed using an industrial benchmark (SPECjAppServer2004) and quantifies the scalability of the approach with different databases enriched with some profiling to identify the bottlenecks under different loads and replica configurations. The results of the evaluation show that the replication approach can scale to a few replicas when using a performant database server.