Peer to peer (P2P) systems are traditionally designed to scale to a large number of nodes. However, we focus on scenarios where the sharing is effected only among neighbors. Localized sharing is particularly attractive in scenarios where wide area network connectivity is undesirable, expensive or unavailable. On the other hand, local neighbors may not offer the wide variety of objects possible in a much larger system. The goal of this paper is to investigate a P2P system that shares contents with its neighbors. We analyze the sharing behavior of Apple iTunes users in an University setting. iTunes restricts the sharing of audio and video objects to peers within the same LAN sub-network. We show that users are already making a significant amount of content available for local sharing. We show that these systems are not appropriate for applications that require access to a specific object. We argue that mechanisms that allow the user to specify classes of interesting objects are better suited for these systems. Mechanisms such as bloom filters can allow each peer to summarize the contents available in the neighborhood, reducing network search overhead. This research can form the basis for future storage systems that utilize the shared storage available in neighbors and build a probabilistic storage for local consumption.
The ubiquitous deployment of wireless LAN networks are allowing students to embrace laptops as their preferred computing platform. We investigated the viability of building collaborative applications to share contents amongst student groups. In our application scenario, the university will provide wireless infrastructure throughout the campus but not the storage infrastructure required to store the shared contents. Laptops will likely exhibit weak availability. Hence, these collaborative applications need to tolerate long delays in propagating updates amongst the participants. In this paper, we presented a preliminary analysis of message forwarding behavior under realistically resource constrained node scenarios. Our experiments were based on the observed wireless user behavior at the University of Notre Dame. Our experiments showed the inherent limits of epidemic propagation in real campus wireless network scenarios.
Contemporary systems use centralized as well as peer-to-peer mechanisms for the large scale distribution of media objects. In this work, we investigate a serendipitous mechanism for directly sharing media objects among a local community of wireless users. This localized sharing is attractive when wide area network connectivity is undesirable, expensive or unavailable; especially when the shared media objects are large. With some restrictions, such localized sharing of media objects is also acceptable to content owners. However, localized sharing has to contend with far fewer media providers who may also not offer the variety of objects available from wide-area services. We collected empirical data from the widely deployed Apple iTunes application for our analysis. We showed that users are already making a significant amount of media objects available for serendipitous sharing. Our analysis showed that the shared object annotations exhibited a Zipfian long tail distribution. The availability patterns of wireless iTunes users and the object annotations makes serendipitous sharing inappropriate for scenarios that require access to a specific object. Instead, mechanisms that allow the user to specify classes of interesting objects are better suited for such users. Also, given the smaller scale of these systems, serendipitous sharing can benefit from approaches that allow users to disseminate a compact representation of their shared objects. Though the wireless user availability rates was not as high as what was observed in a corporate desktop setting, a large fraction of the users showed high temporal consistency. This allows for high availability with reasonable replication during weekday daytime hours. We answer important questions regarding the viability of a campus-wide media sharing system.
We evaluate an asynchronous gossiping middleware for wireless users that propagates messages from any group member to all the other group members. This propagation can either be implemented through distributed mechanisms or can be mediated through servers. Our analysis of asynchronous mechanisms using wireless user availability traces from an university, corporation and a hot spot federation shows that the fundamental impediment to the system performance is the wireless user availability patterns. We then investigate the relative performance for several distributed as well as server mediated approaches. We show that pull mechanisms effectively randomizes the times when messages are propagated and thus achieves better performance than push based mechanisms. We then develop an adaptive approach that customizes the propagation frequency using the last session duration and show that this mechanism exhibits good performance when the required propagation intervals are large. We also show that for a given number of gossips, it is preferable to propagate messages to all available nodes rather than increasing the frequency while correspondingly reducing the number of nodes to propagate messages. Our results allow middleware developers to choose the appropriate propagation model to satisfy their application constraints.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.