Implementing flexible object group invocation in networked systems

Distributed applications should be able to make use of an object group service in a number of application specific ways. Three main modes of interactions can be identified; (i) request-reply; a client issues a request to multiple servers and waits for their replies; this represents a commonly occurring scenario when a service is replicated; (ii) group-to-group request-reply; a generalisation of the previous case, where clients are themselves groups; and (iii) Peer Participation: here all the members are regularly multicasting messages (asynchronous invocation); this represents a commonly occurring scenario when the purpose of an application is to share information between members, (e.g., a teleconferencing application). Customisation within each class of interaction is frequently required for obtaining better performance. This paper describes the design and implementation of a flexible CORBA object group service that supports the three types of interactions and enables application specific customisation. Performance figures collected over low latency LAN and high latency WAN are presented to support the case for flexibility