Structuring the process of integrity maintenance (extended version)

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. In this paper we address efficiency issues during the process of integrity maintenance. In this sense, we propose a technique which improves efficiency of existing methods by defining the order in which maintenance of integrity constraints should be performed. Moreover, we use also this technique for being able to handle in an integrated way the integrity constraintsPostprint (published version

A Review of integrity constraint maintenance and view updating techniques

Two interrelated problems may arise when updating a database. On one hand, when an update is applied to the database, integrity constraints may become violated. In such case, the integrity constraint maintenance approach tries to obtain additional updates to keep integrity constraints satisfied. On the other hand, when updates of derived or view facts are requested, a view updating mechanism must be applied to translate the update request into correct updates of the underlying base facts. This survey reviews the research performed on integrity constraint maintenance and view updating. It is proposed a general framework to classify and to compare methods that tackle integrity constraint maintenance and/or view updating. Then, we analyze some of these methods in more detail to identify their actual contribution and the main limitations they may present.Postprint (published version

Aplicació didàctica de metodologies i adaptació d'eines online per a la gestió col·laborativa de projectes

Peer Reviewe

The use of UML activity diagrams and the i* language in the modeling of the balanced scorecard implantation process

Business management is a complex task that can be facilitated using different methodologies and models. One of their most relevant purposes is to align the organization strategy with the daily functioning of the organization. One of these models is the Balanced Scorecard (BSC). In this paper, we propose a modeling strategy for the BSC implantation process. We will model it using UML Activity Diagrams and Strategy Dependency models of the language i*. The Activity Diagrams allow determining the order in which involved activities must be performed, and at the same time, to identify which people has the responsability to carry them out. The Strategic Dependency model allows showing the intentional aspects of the actors involved in the most strategic activities of this process. Finally, relationships among the actors and the people involved in the BSC implantation process are modelled using again the language i*. Although this paper only considers the case study of the BSC implantation, our proposal can be generalized to other implantation processes of systems with a high strategic impact on the organization, like ERP or CRM systems.Peer ReviewedPostprint (published version

L'escriptura medieval i els missatges SMS: dues realitats no tant llunyanes

En aquest article es presenten els resultats d'un estudi realitzat pels seus autors en el que s'analitza la similitud de les abreviatures usades en l'escriptura de missatges SMS via dispositius mòbils i les abreviatures més comuns usades a l'escriptura de l'edat mitja. Aquest estudi es realitza definint una categoria d'abreviatures de referència i la posterior anàlisi en els dos tipus d'escriptur

The cloud hovering over the virtual campus

The Virtual Campus has been around for about 20 years. It provides an online environment that mimics the processes and services of the physical campuses and classrooms. Its adoption is almost complete in countries where Internet access has become ubiquitous. For a time seemed like the innovation in education was happening in the Virtual Campus, but this is no more. Personal Learning Environments, Life Long Learning, MOOCS, Open Educational Resources, Mobile Apps, Gamification, Social Networks, free Cloud based services... al of the above and even more hint that not all the learning today is happening at school or in the Virtual Campus.Peer ReviewedPostprint (author’s final draft

The use of UML activity diagrams and the i* language in the modeling of the balanced scorecard implantation process

Business management is a complex task that can be facilitated using different methodologies and models. One of their most relevant purposes is to align the organization strategy with the daily functioning of the organization. One of these models is the Balanced Scorecard (BSC). In this paper, we propose a modeling strategy for the BSC implantation process. We will model it using UML Activity Diagrams and Strategy Dependency models of the language i*. The Activity Diagrams allow determining the order in which involved activities must be performed, and at the same time, to identify which people has the responsability to carry them out. The Strategic Dependency model allows showing the intentional aspects of the actors involved in the most strategic activities of this process. Finally, relationships among the actors and the people involved in the BSC implantation process are modelled using again the language i*. Although this paper only considers the case study of the BSC implantation, our proposal can be generalized to other implantation processes of systems with a high strategic impact on the organization, like ERP or CRM systems.Facultad de Informátic

Actualització consistent de bases de dades deductives

En aquesta tesi, proposem un nou mètode per a l'actualització consistent de bases de dades deductives. Donada una petició d'actualització, aquest mètode tradueix de forma automàtica aquesta petició en el conjunt de totes les possibles formes d'actualitzar la base de dades extensional de forma que la petició sigui satisfeta i que no es violi cap restricció d'integritat. Aquest nostre mètode està basat en un conjunt de regles que defineixen la diferència entre dos estats consecutius de la base de dades. Aquesta diferència es determina definint explícitament les insercions, esborrats i les modificacions que es poden induir com a conseqüència de l'aplicació d'una actualització a la base de dades. El mètode està basat en una extensió del procediment de resolució SLDNF. Sigui D una base de dades deductiva, A(D) la base de dades augmentada associada, U una petició inicial d'actualització i T un conjunt d'actualitzacions de fets bàsics. Direm que el conjunt T satisfà la petició d'actualització U i no viola cap restricció d'integritat de D si, utilitzant la resolució SLDNF, l'objectiu  U  ¬Ic té èxit amb el conjunt d'entrada A(D)  T. Així doncs, el mètode consistirà en fer tenir èxit a les derivacions SLDNF fracassades. Per a fer-ho, s'inclouran al conjunt T aquelles actualitzacions de fets bàsics que cal realitzar per tal de que la derivació assoleixi l'èxit. Les diferent formes com es pot assolir aquest èxit es corresponen a les diferents solucions a la petició d'actualització U. El mètode proposat es demostra que és correcte i complet. En aquest sentit, es garanteix que donada una petició d'actualització U, el mètode obté totes les possibles formes de satisfer aquesta petició i que, a la vegada, se satisfacin les restriccions d'integritat definides a la base de dades. A diferència d'altres mètodes, el nostre gestiona les modificacions de fets com un nou tipus d'actualització bàsic. Aquest nou tipus d'actualització, junt amb la demostració de correctesa i completesa, és una de les principals aportacions del nostre mètode respecte els mètodes apareguts recentment. La segona gran aportació del nostre mètode és el fet d'utilitzar tècniques per a millorar l'eficiència del procés de traducció de vistes i del procés de manteniment de restriccions d'integritat. Per a millorar l'eficiència del procés de manteniment de restriccions d'integritat, proposem una tècnica per a determinar l'ordre en què cal comprovar les restriccions d'integritat. Aquesta tècnica està basada en la generació en temps de compilació del anomenat Graf de Precedències, el qual estableix les relacions entre violadors i reparadors potencials d'aquestes restriccions. Aquest Graf és utilitzat en temps d'execució per a determinar l'ordre en què es comproven i reparen les restriccions d'integritat. Aquest ordre redueix el nombre de vegades que cada restricció d'integritat ha de ser comprovada (i reparada) després de reparar qualsevol altre restricció. Per a millorar l'eficiència del procés d'actualització de vistes, proposem fer una anàlisi de la petició d'actualització, del contingut de la base de dades i de les regles de la base de dades augmentada abans d'iniciar la traducció de la petició d'actualització U. Aquesta anàlisi té com a objectiu el minimitzar el nombre d'accessos al contingut de base de dades que cal realitzar per a traduir la petició d'actualització, i per altra banda, aquesta anàlisi també ha de permetre determinar quines alternatives no podran donar lloc a una traducció vàlida a la petició U, permetent així, considerar únicament aquelles alternatives que sí proporcionaran una traducció vàlida a U.Deductive databases generalize relational databases by including not only base facts and integrity constraints, but also deductive rules. Several problems may arise when a deductive database is updated. The problems that are addressed in this thesis are those of integrity maintenance and view updating. Integrity maintenance is aimed to ensure that, after a database update, integrity constraints remain satisfied. When these integrity constraints are violated by some update, such violations must be repaired by performing additional updates. The second problem we deal with is view updating. In a deductive database, derived facts are not explicitly stored into the database and they are deduced from base facts using deductive rules. Therefore, requests to update view (or derived) facts must be appropriately translated into correct updates of the underlying base facts. There is a close relationship between updating a deductive database and maintaining integrity constraints because, in general, integrity constraints can only be violated when performing an update. For instance, updates of base facts obtained as a result of view updating could violate some integrity constraint. On the other hand, to repair an integrity constraint could require to solve the view update problem when integrity constraint may be defined by some derived predicate.In this thesis, we propose a method that deals satisfactorily and efficiently with both problems in an integrated way. In this sense, given an update request, our method automatically translates it into all possible ways of changing the extensional database such that the update request is satisfied and no integrity constraint is violated. Concretely, we formally define the proposed method and we prove its soundness and completeness. The method is sound and complete in the sense that it provides all possible ways to satisfy an update request and that each provided solution satisfies the update request and does not violate any integrity constraint. Moreover, to compare how our method extends previous work in the area, we have proposed a general framework that allows us to classify and to compare previous research in the field of view updating and integrity constraint maintenance. This framework is based on taking into account five relevant dimensions that participate into this process, i.e. the kind of update requests, the database schema considered, the problem addressed, the solutions obtained and the technique used to obtain these solutions. Efficiency issues are also addressed in our approach, either for integrity maintenance as well as for view updating.To perform integrity maintenance efficiently, we propose a technique for determining the order in which integrity constraints should be handled. This technique is based on the generation at compile time of a graph, the Precedence Graph, which states the relationships between potential violations and potential repairs of integrity constraints. This graph is used at run-time to determine the proper order to check and repair integrity constraints. This order reduces significantly the number of times that each integrity constraint needs to be reconsidered after any integrity constraint repair. To improve efficiency during view updating, we propose to perform an initial analysis of the update request, the database contents and the rules of the database. The purpose of this analysis is to minimize the number of accesses to the base facts needed to translate a view update request and to explore only relevant alternatives that may lead to valid solutions of the update request. Furthermore, a detailed comparison with respect to some methods for integrity maintenance that consider efficiency issues is also provided, showing several contributions of our approach

Las prácticas externas curriculares ante un modelo de enseñanza semipresencial : La experiencia de una prueba piloto en el máster de secundaria

.. El Máster de Educación Secundaria se viene realizando en la UPC, desde el curso 2009/10 en las especialidades de Tecnología y Formación Profesional. Inicialmente coordinado por el Instituto de Ciencias de la Educación (ICE) y desde el curso 2015/16 por la Facultad de Informática de Barcelona (FIB) con una coordinación académica conjunta (...) se optó por realizar una especialidad independiente e íntegramente de Formación Profesional, dado las características y particularidades del profesorado de estas especialidades. En Cataluña actualmente se realizan 21 especialidades de Master, 16 de ESO y Bachillerato, y 5 de Formación Profesional. 10 Universidades del sistema educativo catalán, ofrecen enseñanzas del máster de secundaria.Preprin

Perspectives about paradigms in software engineering

There is a broad use of the term “paradigm” in Software Engineer-ing. Concepts such as structured paradigm, cascade paradigm or agent-oriented paradigm are very frequent in software engineering research proposals. In this essay we distinguish between functional and scientific paradigm and we show that the common use of paradigm in Software Engineering is about the func-tional or engineering paradigm rather than scientific paradigm. We distinguish among four possible perspectives and, in this context, we sustain that the scien-tific perspective is intrinsic and hence very difficult to properly identify and de-scribe. We argue that a discussion about the scientific paradigm in Software Engineering could help us to evaluate and improve the research practice in the discipline.Peer ReviewedPostprint (published version