Distributed Asynchronous Collections: Abstractions for Publish/Subscribe Interaction

Publish/subscribe is considered one of the most important interaction styles for the explosive market of enterprise application integration. Producers publish information on a software bus and consumers subscribe to the information they want to receive from that bus. The decoupling nature of the interaction between the publishers and the subscribers is not only important for enterprise computing products but also for many emerging e-commerce and telecommunication applications. It is often claimed that object-orientation is inherently incompatible with the publish/subscribe interaction style. This flawed argument is due to the persistent confusion between object-orientation as a modeling discipline and the specific request/reply mechanism promoted by CORBA-like middleware systems. This paper describes object-oriented abstractions for publish/subscribe interaction in the form of Distributed Asynchronous Collections (DACs). DACs are general enough to capture the commonalities of various publish/subscribe interaction styles, and flexible enough to allow the exploitation of the differences between these flavors.