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Repositories form a central piece of the learning objects technology, providing storage spaces where the objects can be catalogued, located, and retrieved. However, repositories usually support only syntactical and morphological aspects of learning objects metadata for cataloguing and searching purposes. This article proposes two integrated systems, which provide the core services of a semantic repository of learning objects. MSSearch system uses ontology alignment techniques to create a semantic search engine and a semantic database for learning objects metadata. MSSearch supports the integration of multiple educational ontologies through a combination of ontology aligning and mapping mechanisms. In turn, Linnaeus system offers intelligent support for the creation and editing of learning object metadata. This tool employs the technologies of intelligent agents and educational ontologies to provide an intelligent semi-automatic metadata filling service. This article presents the main architectural components, ontological models and interface facilities of these systems. The text finishes with the presentation of the experiments conducted to validate Linnaeus and MSSearch.

This article proposes a decentralized infrastructure for ubiquitous learning environments called Global. The two main contributions of Global are its decentralized strategy and its extensible architecture based on software agents. Global can be specialized to create ubiquitous learning environments through the extension of its agents or through the addition of new agents. The article presents the infrastructure architecture, describing the agents and auxiliary components. Moreover, the article approaches the implementation and evaluation of Global through two applications dedicated to education. The evaluation showed that the infrastructure could be used for the development of decentralized learning systems, supporting specifically the characteristics considered as strategic for ubiquitous learning.