Modeling Load on a Publish/Subscribe System

Message oriented middleware (MOM) systems have been using publish/subscribe mechanism for asynchronous messaging among backend servers. Latest developments in modern Web-based clients have extended the use of publish/subscribe mechanism from backend servers to front-end clients. Some of the recently proposed protocols, like Bayeux, use topic-based publish/subscribe mechanism to exchange messages between clients and servers. This paper shares our experience in designing a load generation framework for benchmarking of an HTTP publish/subscribe server. It analyzes topic-based publish/subscribe domain by identifying major domain entities. It documents issues and challenges in load generation and benchmarking of such systems. It presents a model to represent a topic-based publish/subscribe system. We also share our experience in using the proposed model for load-generation and benchmarking of an HTTP/Bayeux based publish/subscribe server implementation. Some implementation details about our benchmarking framework, including an XML schema to represent a set of workloads, are shared. The paper is concluded by sharing shortcomings in the proposed model, and our plans on extending this work to other asynchronous and synchronous messaging paradigms.