Extensible metadata repository for information systems

Thesis submitted to Faculdade de Ciências e Tecnologia of the Universidade Nova de Lisboa, in partial fulfillment of the requirements for the degree of Master in Computer ScienceInformation Systems are, usually, systems that have a strong integration component and some of those systems rely on integration solutions that are based on metadata (data that describes data). In that situation, there’s a need to deal with metadata as if it were “normal”information. For that matter, the existence of a metadata repository that deals with the integrity, storage, validity and eases the processes of information integration in the information system is a wise choice. There are several metadata repositories available in the market, but none of them is prepared to deal with the needs of information systems or is generic enough to deal with the multitude of situations/domains of information and with the necessary integration features. In the SESS project (an European Space Agency project), a generic metadata repository was developed, based on XML technologies. This repository provided the tools for information integration, validity, storage, share, import, as well as system and data integration, but it required the use of fix syntactic rules that were stored in the content of the XML files. This situation causes severe problems when trying to import documents from external data sources (sources unaware of these syntactic rules). In this thesis a metadata repository that provided the same mechanisms of storage, integrity, validity, etc, but is specially focused on easy integration of metadata from any type of external source (in XML format) and provides an environment that simplifies the reuse of already existing types of metadata to build new types of metadata, all this without having to modify the documents it stores was developed. The repository stores XML documents (known as Instances), which are instances of a Concept, that Concept defines a XML structure that validates its Instances. To deal with reuse, a special unit named Fragment, which allows defining a XML structure (which can be created by composing other Fragments) that can be reused by Concepts when defining their own structure. Elements of the repository (Instances,Concepts and Fragment) have an identifier based on (and compatible with) URIs, named Metadata Repository Identifier (MRI). Those identifiers, as well as management information(including relations) are managed by the repository, without the need to use fix syntactic rules, easing integration. A set of tests using documents from the SESS project and from software-house ITDS was used to successfully validate the repository against the thesis objectives of easy integration and promotion of reuse

BLOC: a Trait-Based Collections Library – a Preliminary Experience Report

International audienceA trait is a programming construct which provides code reusability. Traits are groups of methods that can be reused orthogonally from inheritance. Traits offer a solution to the problems of multiple inheritance by providing a behavior-centric modularity. Since traits offer an alternative to traditional inheritance-based code reuse, a couple of questions arise. For example, what is a good granularity for a Trait enabling reuse as well as plug ease? How much reuse can we expect on large existing inheritance-based hierarchies? In this paper we take as case study the Smalltalk Collection hierarchy and we start rewriting it from scratch using traits from the beginning. We show how such library can be built using traits and we report such a preliminary experience. Since the Collection library is large, we focused and built the main classes of the library with Traits and report problems we encountered and how we solved them. Results of this experience are positive and show that we can build new collections based on the traits used to define the new library kernel

Lessons from the future: ICT scenarios and the education of teachers

This paper reviews significant events of the last 25 years in schools and teacher education in England and looks ahead to the next 25 years. Various scenarios for the future are examined and the potential is considered for new forms of teachers' initial education and continuing professional development using information and communications technology. It is concluded that the current centrally-controlled national system is increasingly inappropriate to present needs and will fracture under the combination of pressures of a commodified education market, learners' consumerist expectations of personalised provision, and networks of informal learning enabled by widespread access to portable communications technology. Four lessons from this future prediction are drawn, with recommendations for radical changes in government policy and orientation. © 2005 Taylor & Francis