A fundamental problem encountered in designing decentralized social applications is the issue of efficiently locating target nodes in social peer-to-peer networks based on local information only. The unique “small-world” phenomenon of social networks shows that a typical pair of nodes is connected by very short chains of intermediate friends, and individuals are able to collectively discover such short paths. In this paper, we propose a decentralized algorithm that exploits this “small-world” phenomenon to discover efficient routes to reach target nodes in unstructured social overlays. In order to test the performance of this algorithm, we simulate it on a real-world social graph dataset crawled from a large online social networking website (LiveJournal). Compared with other related works, the simulation results show that our proposed decentralized social routing algorithm not only shortens the median length of the search path, but also increases the success rate of finding such routes between arbitrary pair of nodes in the LiveJournal social graph.

In the past few years, many peer-to-peer microblogging solutions have been proposed and/or implemented utilizing various technologies such as DHTs, multicast trees, and/or gossip protocols. These previous works address the issue of privacy and performance in a variety of ways including the use of session keys for message encryption or direct connections for low latency communication. We propose a decentralized microblogging service which takes advantage of available peer-to-peer virtual private networking (P2PVPN) technologies which provide privacy and low-latency communication in the common case of P2P messaging among social peers. Leveraging the private IP connectivity of P2PVPNs, our design utilizes both IP multicasting and random walks to ensure that peers are able to publish messages with varying degree of scope (i.e. friends, friends of friends, and/or the public). We study the implications of our data dissemination mechanism for a decentralized microblogging service through simulation-based analysis based on synthetic social graphs. Overall, our experimental results show that peers can effectively follow each other's updates with acceptable overhead. Through the use of our pseudo-random-walk algorithm, we estimate that, in a 900K social graph, with a TTL of 100, a user can retreive updates from anyone in the social graph 55% of the time, but by increasing the TTL to 400 that hit rate increases to 95%.

Microblogging services such as Twitter have become an indispensable communication tool on the Internet. However, due to their centralized nature, microblogging services have been susceptible to blocking by governments and powerful groups. To address this issue, we present a peer-to-peer microblogging service that is resistant to government intrusions and censorship. The strength of our design lies in the fact that we leverage trusted, peer-to-peer connections for the dissemination of information. Our proposed design consists mainly of two key components: a microblogging service which uses UDP and IP multicasting to push and pull updates, and a peer-to-peer VPN (SocialVPN) which enable IP multicasting over the Internet and provide direct IP connectivity among social peers. We also implemented and deployed a prototype to show the feasibility of our approach.

OpenCL has emerged as the open standard for parallel programming for heterogeneous platforms enabling a uniform framework to discover, program, and distribute parallel workloads to the diverse set of compute units in the hardware. For that reason, there have been efforts exploring the advantages of parallelism from the OpenCL framework by offloading GPGPU workloads within an HPC cluster environment. In this paper, we present an OpenCL-based remote offloading framework designed for mobile platforms by shifting the motivation and advantages of using the OpenCL framework for the HPC cluster environment into mobile cloud computing where OpenCL workloads can be exported from a mobile node to the cloud. Furthermore, our offloading framework handles service discovery, access control, and data privacy by building the framework on top of a social peer-to-peer virtual private network, Social VPN. We developed a prototype implementation and deployed it into local- and wide-area environments to evaluate the performance improvement and energy implications of the proposed offloading framework. Our results show that, depending on the complexity of the workload and the amount of data transfer, the proposed architecture can achieve more energy efficient performance by offloading than executing locally.

The ability to define domain names for resources in a collaborative virtual organization is usually reserved to network administrators through centralized domain name servers. We propose SocialDNS, a decentralized, naming service that gives individual collaborators the power to choose the domain nam

Peer-to-Peer (P2P) overlays provide a framework for building distributed applications consisting of few to many resources with features including self-configuration, scalability, and resilience to node failures. Such systems have been successfully adopted in large-scale Internet services for content delivery networks, file sharing, and data storage. In small-scale systems, they can be useful to address privacy concerns as well as support for network applications that lack dedicated servers. The bootstrap problem, finding an existing peer in the overlay, remains a challenge to enabling these services for small-scale P2P systems. In large networks, the solution to the bootstrap problem has been the use of dedicated services, though creating and maintaining these systems requires expertise and resources, which constrain their usefulness and make them unappealing for small-scale systems. This paper surveys and summarizes requirements that allow peers potentially constrained by network connectivity to bootstrap small-scale overlays through the use of existing public overlays. In order to support bootstrapping, a public overlay must support the following requirements: a method for reflection in order to obtain publicly reachable addresses, so peers behind network address translators and firewalls can receive incoming connection requests; communication relaying to share public addresses and communicate when direct communication is not feasible; and rendezvous for discovering remote peers, when the overlay lacks stable membership. After presenting a survey of various public overlays, we identify two overlays that match the requirements: XMPP overlays, such as Google Talk and Live Journal Talk, and Brunet, a structured overlay based upon Symphony. We present qualitative experiences with prototypes that demonstrate the ability to bootstrap small-scale private structured overlays from public Brunet or XMPP infrastructures.

Virtual networks (VNs) provide methods that simplify resource management, deal with connectivity constraints, and support legacy applications in distributed systems, by enabling global addressability of VN-connected machines through either a common layer 2 Ethernet or a NAT-free layer 3 IP network. This paper presents a novel VN design that supports dynamic, seamless addition of new resources with emphasis on scalability in a unified private IP address space. Key features of this system are: (1) Scalable connectivity via a P2P overlay with the ability to bypass overlay routing in LAN communications, (2) support for static and dynamic address allocation in conjunction with virtual nameservers through a distributed data store, and (3) support for transparent migration of IP endpoints across widearea networks.

Deploying virtual organizations (VOs) is difficult for small- and medium-scale collaborations: the overheads in establishing and managing trust, and in deploying and managing computational resources distributed across multiple organizations are daunting to many potential users, presenting a barrier to entry that significantly hinders wider deployment of VOs. We advocate an approach where social networking and self-configuring overlay virtual networks are integrated in a novel way that allows simple deployment and management of ad-hoc infrastructures for VOs. There are three central principles in our approach: (1) user relationships which have been increasingly recorded in social networking systems provide the opportunity to bootstrap trust relationships; (2) connections established at a social networking layer can efficiently be mapped to the IP layer of virtual network overlays to support existing TCP/IP applications for collaboration and resource sharing while maintaining security against untrusted parties; and (3) systems integrating social and virtual networks can be self-configuring, enabling deployment of collaborative infrastructures by non-experts. We discuss motivations for this approach, describe a prototype implementation which integrates the Facebook social network and the IPOP overlay network, and discuss a use case scenario towards ad-hoc social cycle-sharing virtual Condor pools.