The decoupled nature of publish-subscribe (pub-sub) paradigm has gained popularity as a communication mechanism for distributed systems developed for decentralised networks. However, the lack of configurable and measurable properties in current decentralised pub-sub services introduces the issue of limited customisation. This shortcoming leads to the inability to meet different requirements needed by various application domains. In this paper, we address the challenge of supporting configurable properties in an overlay-oriented pub-sub scheme for decentralised networks. We use the measurable feature produced by the configurable properties to develop a mathematical model to analyse the behaviour of the pub-sub scheme with respect to important input factors such as distributions of subscriptions and events. These input factors ultimately affect the widely regarded performance requirement. Finally, we demonstrate the feasibility of our scheme and the validity of the derived model with a series of simulations.