Enric Mayol

A Survey of Current Methods for Integrity Constraint Maintenance and View Updating

During the process of updating a database, two interrelated problems could arise. On one hand, when an update is applied to the database, integrity constraints could become violated, thus falsifying database consistency. In this case, the integrity constraint maintenance approach tries to obtain additional updates to be applied to re-establish database consistency. On the other hand, when an update request consist on updating some derived predicate, a view updating mechanism must be applied to translate the update request into correct updates on the underlying base facts. In this paper, we propose a general framework to compare and classify current methods in the field of view updating and integrity constraint maintenance. In this sense, we classify them considering how they tackle with both problems and, we also state the main drawbacks these methods have.

SYSTEMATIC CONSTRUCTION OF i STRATEGIC DEPENDENCY MODELS FOR SOCIO-TECHNICAL SYSTEMS

Goal- and agent-oriented models have become a consolidated type of artifact in various software and knowledge engineering activities. Several languages exist for representing such type of models but there is a lack of associated methodologies for guiding their construction up to the necessary level of detail. In this paper we present RiSD, a method for building Strategic Dependency (SD) models in the i* notation. RiSD is defined in a prescriptive way to reduce uncertainness when constructing the model. RiSD tackles three fundamental issues: (1) it tends to reduce the average size of the resulting models; (2) it defines some traceability relationships among model elements; (3) it provides some lexical and syntactical conventions. As a result, we may say that RiSD supports the construction process of goal- and agent-oriented models whilst increasing their understanding.

Addressing Efficiency Issues During the Process of Integrity Maintenance

We address efficiency issues during the process of integrity maintenance. In this sense, we propose a technique that improves efficiency of existing methods by defining the order in which maintenance of integrity constraints should be performed. Moreover, we integrate view updating into integrity maintenance and we propose a technique for translating view updates efficiently, aimed at reducing the number of alternatives considered during the process of view updating and the EDB accesses required to perform this translation.

Consistency preserving updates in deductive databases

We deal with view updating and integrity constraint maintenance. View updating is concerned with translating a request to update derived facts into updates of the underlying base facts. Integrity constraint maintenance is aimed to perform the necessary repairs to guarantee that a set of base fact updates does not violate database consistency. We define a method that deals with these problems in an integrated way and we show that it is sound and complete. Soundness ensures that our method obtains only correct solutions while completeness guarantees that we obtain all valid minimal solutions. We also propose set of techniques to provide an efficient implementation of our method.

Clustering Projects for eLearning Interoperability

Since the beginning of the discipline, eLearning has been about innovation. New software, systems, contents and tools are being created and experimented with and in constant evolution. But when systems, contents and tools become successful and part of the regular infrastructure of educational institutions, interoperability becomes an issue. Systems that are consolidated and regularly used need to be able to interoperate with new ones. And the new tendencies need to fit within the current infrastructure. This paper states how several research and development projects with heterogeneous funding sources and locations worldwide, gathered together to find a solution to this common problem, providing open specifications and standards, plus Free/Libre, Open Source reference implementations.

Goal-Driven Agent-Oriented Software Processes

The quality of software processes is acknowledged as a critical factor for delivering quality software systems. Any initiative for improving the quality of software processes requires their explicit representation and management. A current representational metaphor for systems is agent orientation, which has become one of the recently recognized engineering paradigms. In this article, we argue for the convenience of representing the software process using an agent-oriented language to model it and a goal-driven procedure to design it. Particularly we propose using the i* framework which is both an agent- and a goal-oriented modeling language. We review the possibilities of i* as a software process modeling language, and we also show how success factors can be made explicit in i* representations of the software processes. Finally, we illustrate the approach with an example based on the development of a set of ergonomic and safety software tools

Structuring the Process of Integrity Maintenance

Two different approaches have been traditionally considered for dealing with the process of integrity constraints enforcement: integrity checking and integrity maintenance. However, while previous research in the first approach has mainly addressed efficiency issues, research in the second approach has been mainly concentrated in being able to generate all possible repairs that falsify an integrity constraint violation.

Extending tropos for a prolog implementation: a case study using the food collecting agent problem

There is a recognized lack of Agent-Oriented Methodologies to translate a design into a computational logic implementation. In this paper we address this problem by extending Tropos, which is one of the most used methodologies to design agent systems. We show our proposal with the Food Collecting Agent Problem in which a team has to collect food in a grid-like world. Our solution includes autonomous behaviour, beliefs, multiple roles playing, communication and cooperation. The main contribution is the proposal to generate a Prolog implementation from a Tropos design by first extending the Tropos de-tailed design and second illustrating how to get a set of Prolog clauses for this design. In addition we show a performance evaluation of our Prolog implementation which confirms that our solution for the case study is effective and allows a simple configuration of the resulting program.

Dealing with Modification Requests During View Updating and Integrity Constraint Maintenance

An important problem that arises when updating a deductive database is that of integrity constraint maintenance. That is, given a consistent database and an update request, to obtain all possible updates of base facts such that the request is satisfied and no integrity constraint is violated. This problem becomes more complex when view updates are also taken into account. In this paper we define a method for view updating and integrity constraint maintenance in deductive databases. We propose a new method that is sound and that improves current methods by dealing with three kinds of updates: insertion, deletion and modification updates on base and derived predicates. Moreover, due to the inclusion of an specific modification operator, the own definition of the method deals with key information of base and derived predicates.

TSUGI: a framework for building PHP-based learning tools

Innovation on ICT-based learning depends on the ability of researchers, developers and services (and content) providers to push new kinds of tools and services in real life contexts. This implies that new developments need to be interoperable with the current LMS that are running almost everywhere. Thus, either new developments have to be custom built for every LMS or there is a real need for an interoperability standard Over the last 8 years IMS Global Learning Consortium has pushed the IMS Learning tools interoperability as the missing standard. IMS LTI has been developed in collaboration with the major LMS and tools authors in a long process where reference implementations and automated compliance tests have been created, and IMS LTI is supported for all the major commercial and open source LMS. But despite the collaborative open process there are different versions of the standard (Simple LTI, Basic LTI, LTI 1.0, LTI 1.1 and soon LTI 2.0) and there are subtle differences in the implementation of LTI provided by each LMS, which defeats the whole purpose of having an interoperability standard. For this reason the TSUGI project has been created: to provide a framework that makes as simple as possible to develop and deploy LTI applications.