TOPS - A new design for transactions in publish/subscribe middleware

Publish/subscribe is a common messaging paradigm used for asynchronous communication between applications. Synchronous publish/subscribe middleware exist but are less common because they must address two main performance difficulties, the first being that message dissemination involves larger delays and the second being that resources remain locked for a much longer period of time. Hermes Transaction Service (HTS) is such a middleware, which is capable of treating a group of publications as a transaction. In this paper, we propose a design for a Transactional publish/subscribe middleware, based on HTS. Accordingly, we name the middleware TOPS - Transaction Oriented Publish/Subscribe. We present the detailed functionality and architecture of TOPS and its differences with HTS. To demonstrate the advantages of the TOPS middleware, we describe how different strategies of replication may be implemented all using the middleware proposed.