Improving Dissemination Reliability of P2P Topic-Based Publish-Subscribe Systems Exploiting Node Regularity

Publish-subscribe paradigm of communication is one of the most popular and powerful models for services on the Web. Given the increase in popularity of P2P systems and the benefits of them over centralized versions,researchers have created interest in making P2P publish-subscribe systems. However, P2P systems' characteristic property is that nodes in them come and go from the system as they please, forming churn. Recent studies of P2P networks have found that nodes tend to have recurring patterns of availability which are regular over time. There have also been studies for taking advantage of this regular behavior of the nodes in distributed storage systems. The purpose of this thesis is to research into the possibility of using the regularity in node availability for P2P topic based publish-subscribe systems. We explore more into detail this property of the nodes in order to determine which parameters affect the perception of nodes as being regular. We create a generic service called GRID that identifies a node's own regularity pattern and discovers other regular nodes in the system for a specific timeslot. We later make an application that takes advantage of GRID to prove that this property of the nodes might be used to increase the dissemination reliability and speed of an existing P2P topic-based publish subscribe system called PolderCast. We show that, while introducing a small amount of unfairness and higher number of connections on the nodes, the overall dissemination is improved, especially in cases of high churn.