Resumo em Inglês:

Pharos is a collaborative application which enables users to share document annotations. Annotations of a same subject are stored altogether in channels, and channels are replicated to improve performance. What characterises data replication in a collaborative application like Pharos is the way users see data. If, for instance, mutual consistency is required, then collaboration should be synchronous. On the other hand, if remote users can work in disconnected mode, collaboration can be asynchronous with weaker constraints on data freshness. In this paper, we focus on asynchronous replication which is typically required on the Web. We propose an optimistic replication model based on lazy group replication and a protocol to detect and resolve potential conflicts to refresh the replicas. This protocol is based on the ordering of write operations at each site using its timestamps values. Careful log management is the key to its implementation. We describe the implementation of our model in the Pharos application.

Resumo em Inglês:

This paper presents a new approach for generating configured and flexible middleware systems for integration of heterogeneous and distributed data. The configuration is based on the selection of an adequate set of database services components and flexibility is achieved by adopting framework techniques. A control model checks the configuration, manages the communication between components and dynamically schedules tasks. The objective is to build tailored integration middleware systems, using a minimum number of components. In addition, the use of framework allows for increased software quality and reduced development effort.

Resumo em Inglês:

Web Data Warehouses have been introduced to enable the analysis of integrated Web data. One of the main challenges in these systems is to deal with the volatile and dynamic nature of Web sources. In this work we address the effects of adding/removing/changing Web sources and data items to the Data Warehouse (DW) schema. By managing source evolution we mean the automatic propagation of these changes to the DW. The proposed approach is based on a wrapper/mediator architecture, which reduces the impact of Web source changes on the DW schema. This paper presents this architecture and analyses some selected evolution cases in the context of Web DW.

Resumo em Inglês:

Automating semantic matching of attributes for the purpose of information integration is challenging, and the dynamics of the Web further exacerbate this problem. Believing that many facets of metadata can contribute to a resolution, we present a framework for multifaceted exploitation of metadata in which we gather information about potential matches from various facets of metadata and combine this information to generate and place confidence values on potential attribute matches. To make the framework apply in the highly dynamic Web environment, we base our process on machine learning when sufficient applicable data is available and base it otherwise on empirically observed rules. Experiments we have conducted are encouraging, showing that when the combination of facets converges as expected, the results are highly reliable.

Resumo em Inglês:

Personalization is a key factor for differentiating services and retaining customers in World Wide Web sites. On the other hand, designing and implementing an efficient personalization strategy is still a challenge, because of the complexity of the techniques used and the variety of sites and customers, which are always evolving. This paper presents a functional model of personalization strategies that allows not only a simple and concise specification of those strategies, but also their simulation and validation. We demonstrate our model through e-Personal, a framework for estimating the effectiveness of personalization strategies. The framework guides the user through the process of specifying a strategy and estimates its impact based on previous interactions of customers with the site. It is based on our functional model and we illustrate its utilization for designing personalization strategies for a web portal. Our experiments are based on actual logs and show that the proposed framework enhances significantly the personalization process, indicating the goodness of the strategy design, the reliability of input data, and the impact of implementation decisions on the effectiveness of personalized sites.

Resumo em Inglês:

Component Based Development (CBD) aims at constructing software through the integration, using interfaces and contracts, between pre-existing components. The main goal of this work is to provide access to component that can be published at the Web, retrieved, and reused in all phases of an application development within a given domain. We present an architecture for software components reuse by using a mediation layer that integrates the semantics of Web components with previously registered components from a virtual library of components. In our architecture, components are described through XML documents and published by local repositories or remote servers. The innovative aspect of our proposal is the combination of mediators and software agents for reusable component retrieval within a Domain Engineering context. Mediators can represent application domain as well as integrate the description of domain related components. Queries can be issued to the mediation layer and processed by the GOA Object Server, which presents the query results as a list of suggested components along with its repository link in XML. Software agents are responsible for web component discovery and filtering. Techniques such as user models (profiles), and recommendations are used for presenting a ranked list of links. Finally, resulting links from mediators and web post-processed results are combined and presented to the user.