On the Use of Enterprise Java Beans 2.0 Local Interfaces

Abstract

The collocated invocation overhead of Enterprise JavaBeans (EJB) 1.1 remote interfaces is often a severe problem, in particular with distributed application architectures like J2EE where collocated calls among beans frequent. EJB 2.0 introduces local interfaces as a solution to the collocation overhead and related problems, based on the implicit assumption that EJB components can be clustered. This paper evaluates the use and usefulness of local interfaces, taking the approach to analyze which role EJB components from typical state-of-the-art applications play in clusters. It is shown that, under frequent conditions, components intended to be cluster-internal must be made cluster facades, and possibly have both remote and local interfaces, or the cluster size increases dramatically. The consequence is that an improved application performance, for which local interfaces have been introduced, can often be attained only at the cost of an increased system complexity and programming effort.