Incremental replication for mobility support in OBIWAN

Abstract

The need for sharing is well known in a large number of distributed collaborative applications. These applications are difficult to develop for wide area (possibly mobile) networks because of slow and unreliable connections. For this purpose, we developed a platform called OBIWAN that: i) allows the application to decide, in run-time, the mechanism by which objects should be invoked, remote method invocation or invocation on a local replica, ii) allows incremental replication of large object graphs, iii) allows the creation of dynamic clusters of data, and iv) provides hooks for the application programmer to implement a set of application specific properties such as relaxed transactional support or updates dissemination. These mechanisms allow an application to deal with situations that frequently occur in a (mobile) wide-area network, such as disconnections and slow links: i) as long as objects needed by an application (or by an agent) are colocated, there is no need to be connected to the network, and ii) it is possible to replace, in run-time, remote by local invocations on replicas, thus improving the performance and adaptability of applications. The prototype is developed in Java, is very small and simple to use, the performance results are very encouraging, and existing applications can be easily modified to take advantage of OBIWAN.