Wojciech Galuba

Learn More
The ever-increasing amount of information flowing through Social Media forces the members of these networks to compete for attention and influence by relying on other people to spread their message. A large study of information propagation within Twitter reveals that the majority of users act as passive information consumers and do not forward the content(More)
Microblogging sites are a unique and dynamic Web 2.0 communication medium. Understanding the information flow in these systems can not only provide better insights into the underlying sociology, but is also crucial for applications such as content ranking, recommendation and filtering, spam detection and viral marketing. In this paper, we characterize the(More)
Simulators are a commonly used tool in peer-to-peer systems research. However, they may not be able to capture all the details of a system operating in a live network. Transitioning from the simulation to the actual system implementation is a non-trivial and time-consuming task. We present ProtoPeer, a peer-to-peer systems prototyping toolkit that allows(More)
Wireless ad hoc networks are inherently vulnerable, as any node can disrupt the communication of potentially any other node in the network. Many solutions to this problem have been proposed. In this paper, we take a fresh and comprehensive approach that addresses simultaneously three aspects: security, scalability and adaptability to changing network(More)
Trust and reputation systems have proven to be essential to enforcing cooperative behavior in peer-to-peer networks. We briefly describe the current approaches to building reputation systems: social networks formation, probabilistic estimation, and game theoretic models. We then observe that all of the current models make a number of simplifying assumptions(More)
The correct functioning of a peer-to-peer network relies on cooperative behavior of peers as service providers. Current approaches to detection and deterrence of non-cooperative behavior, such as reputation systems, rely on (1) global sharing of observations about service provisioning and (2) global authentication. These two factors severely impair the(More)
Simulators are an excellent tool for quick systems prototyping and large-scale parameter sweeps, but they cannot match the accuracy of live network evaluations. Switching from the simulation to the actual implementation often requires a considerable development effort. Network I/O implementation, measurement instrumentation, deployment automation and(More)
Many structured overlay networks rely on a ring invariant as a core network connectivity element. The responsibility ranges of the participating peers and navigability principles (greedy routing) heavily depend on the ring structure. For correctness guarantees, each node needs to eagerly maintain its immediate neighboring links the ring invariant. However,(More)
In sufficiently large heterogeneous overlays message loss and delays are likely to occur. This has a significant impact on overlay routing, especially on longer paths. The existing solutions to this problem rely on message redundancy to mask the loss and delays. This incurs a significant bandwidth cost. We propose the Forward Feedback Protocol (FFP) which(More)