Abstract-Confluence of technologies represented by geolocation, geo-sensing, context and activity recognition, and smart phones with rich sensors is opening up new avenues for media-rich social interactions for a spectrum of applications from entertainment, to commerce, to emergency response. This paper addresses the challenges in membership management of a transient social network (TSN), a community of users with mobile devices engaging in social activities of common interest within specific temporal and geographical locality (e.g., flea market, emergency response, local auctions, etc.). Creating and maintaining viable transient social communities requires solving a number of significant challenges including managing the dynamically created social graph, maintaining connectivity across heterogeneous nodes and interfaces and efficient message delivery among the nodes in a community.Micrograph is a middleware for managing community membership in TSNs. It helps nodes to discover and participate with other nodes based on device-level, or application-level attributes. It allows a node to simultaneously participate in multiple distinct social communities by overlaying multiple TSNs on top of the available nodes in the physical network. Micrograph gives complete isolation for the activities of a node in each of the TSNs that a node may be participating in simultaneously and it also gives complete transparency to a participant as to the membership of a TSN in which he/she is involved in. In this paper, we present the design and implementation of Micrograph, a proof-of-concept implementation of the middleware using Android platforms, four applications to show the feasibility of Micrograph, and simulation-based evaluation of the implemented prototype.

Abstract. Social networks such as Facebook and Secondlife are popular. Wireless devices abound from affluent countries to developing countries. Social networks need wide area Internet support. Wireless interfaces offer ad hoc networking capability, without the need for infrastructure support. Web on Demand (WoD) aims to bridge the gap between ad hoc social networks (people in close proximity with shared interests) and ad hoc networking. A key requirement for WoD is transparent connection management. This paper makes three contributions: First, an abstraction called VirtualConnection for transparent connection creation and migration, with socket-like API; second, an implementation on iPAQs (Windows Mobile) as a user level library, and proof of efficacy of using this abstraction for realizing WoD; third, evaluations to establish the performance of this abstraction. In particular, we show the performance degradation due to virtualizing the connection is negligible.