In an attempt to find ways to improve persistence rates in its distance courses, the Cegep@distance introduced different forms of collaboration (peer interaction and collaborative learning activities) in selected courses. A mixed methodology was used to understand the effects of these interventions, relying on a quasiexperimental design for the evaluation of the effects of peer interaction. The...

We describe a scenario of independent TV programme dissemination where viewers receive their own tailored channel created from content in which they’re interested. We focus primarily on the problem of distributing the content from the producers to all interested viewers. Our approach is based on a multicast scheme called implicit group messaging, realised as a distributed structured peer-to-pee...

Existing peer-to-peer systems rely on overlay network protocols for object storage and retrieval and message routing. These overlay protocols can be broadly classified as structured and unstructured – structured overlays impose constraints on the network topology for efficient object discovery, while unstructured overlays organize nodes in a random graph topology that is arguably more resilient...

In structured and unstructured Peer-to-Peer (P2P) systems, frequent joining and leaving of peer nodes causes topology mismatch between the P2P logical overlay network and the physical underlay network. This topology mismatch problem generates high volumes of redundant traffic in the network. This paper presents Common Junction Methodology (CJM) to reduce network overhead by optimize the overlay...

Load balancing is one of the main challenges of every structured peer-to-peer (P2P) system that uses distributed hash tables to map and distribute data items (objects) onto the nodes of the system. In a typical P2P system with N nodes, the use of random hash functions for distributing keys among peer nodes can lead to O(log N) imbalance. Most existing load balancing algorithms for structured P2...

In the framework of peer to peer distributed systems, the problem of anonymity in structured overlay networks remains a quite elusive one. It is especially unclear how to evaluate and improve sender anonymity, that is, untraceability of the peers who issue messages to other participants in the overlay. In a structured overlay organized as a chordal ring, we have found that a technique originall...

Random peer selection is used by numerous P2P applications; examples include application-level multicast, unstructured file sharing, and network location mapping. In most of these applications, support for a heterogeneous capacity distribution among nodes is desirable: in other words, nodes with higher capacity should be selected proportionally more often. Random peer selection can be performed...

Balancing structured peer-to-peer graphs, including zone-size distributions, has recently become an important topic of DHT research [1], [2], [6], [20], [32], [38]. To bring analytical understanding into the various peer-join mechanisms, we study how zone-balancing decisions made during the initial sampling of the peer space affect the resulting zone sizes and derive several asymptotic bounds f...

Several recently emerged Internet services make use of application-level or overlay networks. Examples of such services include overlay multicast, structured peer-topeer lookup services, and peer-to-peer file sharing. Many of these services could benefit from enabling participating end hosts to estimate their relative network locations within the overlay. In this thesis, we present PCoord, a pe...