Military Communications and Information Technology: A Trusted ...

A Robust and Scalable Peer-to-Peer
Publish/Subscribe Mechanism
Tobias Ginzler
Communication Systems Fraunhofer FKIE Wachtberg, Germany,
tobias.ginzler@fkie.fraunhofer.de
Abstract: In this work a publish/subscribe peer-to-peer mechanism is presented. The purpose
of KadScribe is to enable a subscription-based message dissemination mechanism for a large number
of participants. The mechanism is intended as a building block for other protocols and applications.
Possible applications include SOA messaging, weather information or an instant messaging presence
service. The focus is on best-effort, low data rate services. The special challenges of disadvantaged
networks such as volatile user behavior, low transmission capacity and faulty network connections are
respected. Mechanisms to deal with these challenges in the publish/subscribe system are presented
and evaluated in a simulated network environment.
Keywords: peer-to-peer, publish/subscribe, computer networks
I. Introduction
Peer-to-peer overlay networks first appeared in the late 1990ies and rapidly
gained popularity in the following years. The typical usage scenario was sharing
and downloading of music files in the mp3 file format. File sharing over peer- topeer
– or P2P – networks soon came to notorious fame, because it was mainly used
to exchange copyright protected content. Ongoing legal disputes led to the end
of the most popular file sharing network of that time, Napster, in 2001. The new
feature of Napster was to enable users worldwide to share content and publish information
without the effort of setting up hardware or writing code. The philosophy
of P2P networks was and still is today, that every participant may be consumer of information
as well as a publisher of information. Tim Berners-Lee had the concept
of sharing in mind, “That was what it was designed to be as a collaborative space
where people can interact.” [3]. The need for interaction and collaboration was unbroken
by the end of Napster. Soon the gap left by Napster was filled by numerous
P2P networks, built to overcome the fragile design of the first generation of peerto-peer
networks. A nearly uncountable variety of protocols and P2P applications
exist today. P2P technology is used to distribute software updates or to find persons
for remote software support. Instant messaging relies on P2P overlays [1] as well