Distributed Systems, 2nd Edition

Chapter 21

Social and Peer-to-Peer Networks

21.1 Introduction to Social Networks

A social network depicts a social structure. It is commonly represented by a graph where the nodes are entities, and edges denote a relationship between a pair of entities. Some examples of entities are persons, organizations, various forms of living beings, web pages, cities, and airports. When nodes represent people, an edge may denote a friendship relation between them. When nodes are web pages, an edge from page x to page y may represent the existence of a link from the former to the latter page. When nodes denote businesses, an edge may denote the existence of a business relationship between two businesses. A social network like Facebook® or Twitter® is a modern ...