Resumo em Inglês:

We present our approach to enabling approximate ad hoc queries on terabyte-scale mesh data generated from large scientific simulations through the extension and integration of database, statistical, and data mining techniques. There are several significant barriers to overcome in achieving this objective. First, large-scale simulation data is already at the multi-terabyte scale and growing quickly, thus rendering traditional forms of interactive data exploration and query processing untenable. Second, a priori knowledge of user queries is not available, making it impossible to tune special-purpose solutions. Third, the data has spatial and temporal aspects, as well as arbitrarily high dimensionality, which exacerbates the task of finding compact, accurate, and easy-to-compute data models. Our approach is to preprocess the mesh data to generate highly compressed, lossy models that are used in lieu of the original data to answer users' queries. This approach leads to interesting challenges. The model (equivalently, the content-oriented metadata) being generated must be smaller than the original data by at least an order of magnitude. Second, the metadata representation must contain enough information to support a broad class of queries. Finally, the accuracy and speed of the queries must be within the tolerances required by users. In this paper we give an overview of ongoing development efforts with an emphasis on extracting metadata and using it in query processing.

Resumo em Inglês:

In recent years, the number of information sources offered on the Web has grown tremedously. Support for accessing these information sources has mostly been concentrated on browsing and search tools. Digital libraries and Web directories constitute important initiatives to improve information access, creating and organizing document collections hierarchically, according to different criteria. Search tools, on the other hand, offer a more comprehensive coverage of resources, using robot-based services to collect and index documents, that can be latter accessed using information retrieval techniques. However, technologies applied to search mechanisms on the Web still offer little support to manage document collections, as the association between these documents cannot be explicitly identified, neither by their formats nor by their types. This paper presents a formal structure for organizing and describing collections and their documents on the Web. It is based on a metadata conceptual model which explores relationships between information resources at different levels of granularity. To validate this model, a prototype has been implemented using both a semi-structured and an object-relational database (DB) approach.

Resumo em Inglês:

In this paper we present a system for data integration on the web, where an XML-based mediator plays a key role providing a homogeneous view of different data sources. One novelty of our approach is that we also propose solutions for the problems of generation and maintenance of mediators. Observe that, in dynamic environments, such as the Web, individual data sources may change not only their data but also their schemas. As a result, whenever a local schema changes, the mediator needs to be updated to reflect the modifications. The proposed system uses agents to support mediator generation and maintenance. We specify a set of tasks that must be performed in order to support both generation and maintenance of mediators. In our approach, we use correspondence assertions for specifying the semantics of XML-based mediators.

Resumo em Inglês:

Ontologies are becoming an important mechanism to build information systems. Nevertheless, there is still no systematic approach to support the design of such systems using tools that are common to information systems developers. In this paper, we propose an approach for deriving object frameworks from domain ontologies and then we show the application of this approach in the software process domain.

Resumo em Inglês:

Objects and agents are software engineering abstractions that have many common concerns. However, agents are more complex entities since they encompass additional concerns: their state is driven by beliefs, goals, capabilities and plans, and their behavior is composed of a number of agency properties such as autonomy, adaptation, interaction, learning, mobility, and collaboration. A multi-agent system usually incorporates multiple objects and types of agents, with each agent type addressing distinct agency concerns. These agency concerns typically overlap and interact with each other, and so a disciplined scheme for composition is required. In this context, this paper presents and compares an aspect-based proposal with a new pattern-based proposal for building multi-agent software. Both proposals have the following goals: (i) minimize the misalignments between high-level agent models and object-oriented designs, (ii) promote the separation of agency concerns, (in) provide explicit support for disciplined composition of agency concerns in complex software agents, (iv) incorporate flexible facilities to build different types of software agents, and (v) allow the production of multi-agent software systems that are easy to understand, maintain and reuse. We demonstrate the applicability of the two proposals through the Portalware system, a Web-based environment f or the development of e-commerce portals.

Resumo em Inglês:

Mutation Testing is an approach for assessing the quality of a test case suite by analyzing its ability in distinguishing the product under test from a set of alternative products, the so-called mutants. The mutants are generated from the product under test by applying a set of mutant operators, which produce products with slight syntactical differences. The mutant operators are usually based on typical errors that occur during the software development and can be related to a fault model. In this paper, we propose a language - named MuDeL, - for describing mutant operators aiming not only at automating the mutant generation, but also at providing precision and formality to the operator descriptions. The language was designed using concepts that come from transformational and logical programming paradigms, as well as from context-free grammar theory. The language is illustrated with some examples. We also describe the mudelgen system, developed to support this language.