A 2-tiers p2p Architecture to Navigate the Learning Objects Sea

Learning object repositories (LORs) are a strategic asset for e-learning. In a quite short period the scenario of use has quickly changed from an initial scarcity of learning objects (LOs) to an overabundance disorienting users. To address this problem, we present a conceptual model which leverages on the creation and sharing of comments about the use of LOs as experimented by learners. These comments originate a superstructure on interrelated and distributed LOs in the form of an annotated graph-of-comments. By relying on the graph structure, an ordering feature (based on an automatic ranking of LO) and a mechanism for extracting personalized views (subgraphs and paths in the graph-ofcomments) are provided. Observing that both LORs and users are expected to belong to (possibly) different and autonomous communities, which share data via Internet, we propose a two-tiers architecture based on hybrid peer-topeer technology efficiently realizing the navigation on LORs.