tailieunhanh - Frugal Event Dissemination in a Mobile Environment?

Greenpeace is an independent global campaigning organization that acts to change attitudes and behaviour, to protect and conserve the environment and promote peace. Greenpeace has 3 million supporters and does not accept donations from governments, the EU, businesses or political parties. Greenpeace European Unit is part of the international Greenpeace network, active in over 40 countries worldwide. Based in Brussels, the Unit monitors and analyses the work of the EU institutions, exposes deficient EU policies and laws, and challenges EU decision-makers to implement progressive solutions | Frugal Event Dissemination in a Mobile Environment Sébastien Baehni Chirdeep Singh Chhabra and Rachid Guerraoui School of Computer and Communication Sciences EPFL Abstract. This paper describes an event dissemination algorithm that implements a topic-based publish subscribe interaction abstraction in mobile ad-hoc networks MANETs . Our algorithm is frugal in two senses. First it reduces the total number of duplicates and parasite events received by the subscribers. Second both the mobility of the publishers and the subscribers as well as the validity periods of the events are exploited to achieve a high level of dissemination reliability with a thrifty usage of the memory and bandwidth. Besides our algorithm is inherently portable and does not assume any underlying routing protocol. We give simulation results of our algorithms in the two most popular mobility models city section and random waypoint. We highlight interesting empirical lower bounds on the minimal validity period of any given event to ensure its reliable dissemination. 1 Introduction The publish subscribe pub sub communication abstraction is a very appealing candidate for disseminating events in mobile ad-hoc networks MANETs 1 . In such networks devices are mobile they may not know each other and might not always be up and running. With a pub sub abstraction remote devices can communicate by playing two roles the publishers produce events that are disseminated in the network and subscribers receive events they are interested in. Publishers and subscribers are decoupled in time space and flow 2 . This makes the pub sub abstraction appropriate for loosely coupled MANET applications. Whereas the writing of MANET applications is appealing with a pub sub abstraction the effective implementation of such abstraction is not an easy task. In particular ensuring a reasonable level of reliability of the dissemination is challenging without flooding the entire network. Indeed devices in a MANET can directly .