Topic-Based Causally Ordered Delivery of Event Messages in a Peer-to-Peer (P2P) Model of Publish/Subscribe Systems

Abstract

An event-driven publish/subscribe (PS) model of a distributed system is used in various applications. In this paper, we discuss a peer-to-peer (P2P) model of a topic-based PS system (P2PPS model) where each peer process (peer) can both subscribe interesting topics and publish event messages with topics. In our previous studies, we propose the TBC (topicbased causally delivery) protocol an homogeneous networks where maximum delay time between every pair of peers is same. Here, a pair of event messages are checked if the event messages are related in the topic vector and are causally delivered by taking advantage of physical time and linear time. In this paper, we consider a system where peers are interconnected in heterogeneous networks. Here, maximum delay time between every pair of peers is not same. We propose a heterogeneous TBC (HTBC) protocol where event messages are TBC-causally delivered to target peers in heterogeneous network. We evaluate the HTBC protocol and show the number of pair of event messages unnecessarily ordered is reduced in the HTBC protocol.