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Publications

Publications by José Paulo Leal

2009

Defining programming problems as learning objects

Authors
Leal, JP; Queiros, R;

Publication
World Academy of Science, Engineering and Technology

Abstract
Standards for learning objects focus primarily on content presentation. They were already extended to support automatic evaluation but it is limited to exercises with a predefined set of answers. The existing standards lack the metadata required by specialized evaluators to handle types of exercises with an indefinite set of solutions. To address this issue existing learning object standards were extended to the particular requirements of a specialized domain. A definition of programming problems as learning objects, compatible both with Learning Management Systems and with systems performing automatic evaluation of programs, is presented in this paper. The proposed definition includes metadata that cannot be conveniently represented using existing standards, such as: the type of automatic evaluation; the requirements of the evaluation engine; and the roles of different assets - tests cases, program solutions, etc. The EduJudge project and its main services are also presented as a case study on the use of the proposed definition of programming problems as learning objects.

2009

Designing a user interface for repositories of learning objects

Authors
Leal, JP; Queiros, R;

Publication
Proceedings of the IADIS International Conference e-Learning 2009, Part of the IADIS Multi Conference on Computer Science and Information Systems, MCCSIS 2009

Abstract
This paper presents the design of a user interface for repositories of learning objects. It integrates several tasks, such as submission, browse, search, and comment/review of learning objects, on a single screen layout. This design is being implemented on the web front-end of crimsonHex, a repository of specialized learning objects, developed as part of the EduJudge, a European project that aims to bring automatic evaluation of programming problems to e-Learning systems. © 2009 IADIS.

2009

An architecture for the rapid development of XML-based web applications

Authors
Leal, JP; Gonalves, JB;

Publication
ICEIS 2009 - 11th International Conference on Enterprise Information Systems, Proceedings

Abstract
Our research goal is the generation of working web applications from high level specifications. Based on our experience in using XML transformations for that purpose, we applied this approach to the rapid development of database management applications. The result is an architecture that defines of a web application as a set of XML transformations, and generates these transformations using second order transformations from a database schema. We used the Model-View-Controller architectural pattern to assign different roles to transformations, and defined a pipeline of transformations to process an HTTP request. The definition of these transformations is based on a correspondence between data-oriented XML Schema definitions and the Entity-Relationship model. Using this correspondence we were able produce transformations that implement database operations, forms interfaces generators and application controllers, as well as the second order transformations that produce all of them. This paper includes also a description of a RAD system following this architecture that allowed us to perform a critical evaluation of this proposal.

2012

Orchestration of E-Learning Services for Automatic Evaluation of Programming Exercises

Authors
Queiros, R; Leal, JP;

Publication
JOURNAL OF UNIVERSAL COMPUTER SCIENCE

Abstract
Managing programming exercises require several heterogeneous systems such as evaluation engines, learning objects repositories and exercise resolution environments. The coordination of networks of such disparate systems is rather complex. These tools would be too specific to incorporate in an e-Learning platform. Even if they could be provided as pluggable components, the burden of maintaining them would be prohibitive to institutions with few courses in those domains. This work presents a standard based approach for the coordination of a network of e-Learning systems participating on the automatic evaluation of programming exercises. The proposed approach uses a pivot component to orchestrate the interaction among all the systems using communication standards. This approach was validated through its effective use on classroom and we present some preliminary results.

2003

Mooshak: a Web-based multi-site programming contest system

Authors
Leal, JP; Silva, F;

Publication
SOFTWARE-PRACTICE & EXPERIENCE

Abstract
This paper presents a new Web-based system, Mooshak, to handle programming contests. The system acts as a full contest manager as well as an automatic judge for programming contests. Mooshak innovates in a number of aspects: it has a scalable architecture that can be used from small single server contests to complex multi-site contests with simultaneous public online contests and redundancy; it has a robust data management system favoring simple procedures for storing, replicating, backing up data and failure recovery using persistent objects; it has automatic judging capabilities to assist human judges in the evaluation of programs; it has built-in safety measures to prevent users from interfering with the normal progress of contests. Mooshak is an open system implemented on the Linux operating system using the Apache HTTP server and the TcI scripting language. This paper starts by describing the main features of the system and its architecture with reference to the automated judging, data management based on the replication of persistent objects over a network. Finally, we describe our experience using this system for managing two official programming contests. Copyright (C) 2003 John Wiley Sons, Ltd.

2012

Combining usage and content in an online music recommendation system for music in the long-tail

Authors
Domingues, MA; Gouyon, F; Jorge, AM; Leal, JP; Vinagre, J; Lemos, L; Sordo, M;

Publication
WWW'12 - Proceedings of the 21st Annual Conference on World Wide Web Companion

Abstract
In this paper we propose a hybrid music recommender system, which combines usage and content data. We describe an online evaluation experiment performed in real time on a commercial music web site, specialised in content from the very long tail of music content. We compare it against two stand-alone recommenders, the first system based on usage and the second one based on content data. The results show that the proposed hybrid recommender shows advantages with respect to usage- and content-based systems, namely, higher user absolute acceptance rate, higher user activity rate and higher user loyalty. Copyright is held by the International World Wide Web Conference Committee (IW3C2).

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