A Framework for Prototyping J2EE Replication Algorithms

Abstract

In application server systems, such as J2EE, replication is an essential strategy for reliability and efficiency. Many J2EE implementations, both commercial and open-source, provide some replication support. However, the range of possible strategies is wide, and the choice of the best one, depending on the expected application profile, remains an open research question. To support research in this area, we introduce a framework for prototyping J2EE replication algorithms. In effect, it divides replication code into two layers: the framework itself, which is common to all replication algorithms, and a specific replication algorithm, which is "plugged in" to the framework. The division is defined by an API. The framework simplifies development in two ways. First, it keeps much of the complexity of modifying a J2EE implementation within the framework layer, which is implemented only once. Second, through the API, the replication algorithm sees a highly abstracted view of the components in the server. This frees the designer to concentrate on the important issues that are specific to a replication algorithm, such as communication. We have implemented the framework by extending the open-source J2EE server. Compared to an unmodified server, the framework adds a performance cost of about 22%. Thus, it is quite practical for the initial development and evaluation of replication algorithms. Several algorithms have already been implemented within the framework.

Middleware Support for Adaptive Dependability

“…This is on the one hand the time required by the constraint consistency manager, e.g., accessing the constraint repository to search for affected constraints, and on the other hand running through the replication component that does not replicate if the called method is not a setter changing the state of an entity bean. In this case, the performance drops to about 73% of the "No DeDiSys" configuration, which we consider quite a good achievement as 22% of the 27% loss are caused by the ADAPT replication framework [24]. Consequently, the overhead introduced by our middleware enhancement for empty operations is about 5%.…”

“…The case where methods without associated constraints were called shows the interception overhead introduced by our middleware enhancement as well as the ADAPT replication framework [24]. This is on the one hand the time required by the constraint consistency manager, e.g., accessing the constraint repository to search for affected constraints, and on the other hand running through the replication component that does not replicate if the called method is not a setter changing the state of an entity bean.…”

“…This interceptor is then responsible for appropriately including the CCMgr within the process of an invocation. The implementation of the replication protocol is based on the ADAPT replication framework [24], which also hooks into JBoss through custom interceptors. Unfortunately, the interceptor chain is only traversed if the invocation comes from a call to the interface which is passed through the interceptor chain by the JBoss proxy (EJB container).…”

“…ADAPT [24] provides a replication framework to allow rapid prototyping of replication protocols in J2EE (Java 2 Enterprise Edition) environments. This framework is based upon the JBoss AS.…”

Building Dependable and Secure Web Services

“…Babaoglu, Bartoli, Maverick, Patarin and Wu [4] have described a framework for prototyping J2EE replication algorithms. They divide the replication code into two layers, the framework which is common to all replication algorithms and a specific replication algorithm which is plugged into the framework.…”