Towards a common API for publish/subscribe

Over the last decade a wide range of publish/subscribe (pub/ sub) systems have come out of the research community. However, there is little consensus on a common pub/sub API, which would facilitate innovation, encourage applica-tion building, and simplify the evaluation of existing proto-types. Industry pub/sub standards tend to be overly com-plex, technology-centric, and hard to extend, thus limiting their applicability in research systems. In this paper we propose a common API for pub/sub that is tailored towards research requirements. The API sup-ports three levels of compliance (with optional extensions): the lowest level specifies abstract operations without pre-scribing an implementation or data model; medium compli-ance describes interactions using a light-weight XML-RPC mechanism; finally, the highest level of compliance enforces an XML-RPC data model, enabling systems to understand each other’s event and subscription semantics. We show that, by following this flexible approach with emphasis on extensibility, our API can be supported by many prototype systems with little effort. 1