On the emergent Semantic Web and overlooked issues

The emergent Semantic Web, despite being in its infancy, has already received a lotof attention from academia and industry. This resulted in an abundance of prototype systems and discussion most of which are centred around the underlying infrastructure. However, when we critically review the work done to date we realise that there is little discussion with respect to the vision of the Semantic Web. In particular, there is an observed dearth of discussion on how to deliver knowledge sharing in an environment such as the Semantic Web in effective and efficient manners. There are a lot of overlooked issues, associated with agents and trust to hidden assumptions made with respect to knowledge representation and robust reasoning in a distributed environment. These issues could potentially hinder further development if not considered at the early stages of designing Semantic Web systems. In this perspectives paper, we aim to help engineers and practitioners of the Semantic Web by raising awareness of these issues

An Ontology-Based Autonomic System for Improving Data Warehouse Performances

International audienceWith the increase in the amount and complexity of information, data warehouse performance has become a constant issue, especially for decision support systems. As decisional experts are faced with the management of more complex data warehouses, a need for autonomic management capabilities is shown to help them in their work. Implementing autonomic managers over knowledge bases to manage them is a solution that we find more and more used in business intelligence environments. What we propose, as decisional system experts, is an autonomic system for analyzing and improving data warehouse cache memory allocations in a client environment. The system formalizes aspects of the knowledge involved in the process of decision making (from system hardware specifications to practices describing cache allocation) into the same knowledge base in the form of ontologies, analyzes the current performance level (such as query average response time values) and proposes new cache allocation values so that better performance is obtained

Service-oriented middleware for wireless sensor networks

There is a wide range of applications for wireless sensor networks (WSNs) with different needs. The network infrastructure and data dissemination protocol change according to each specific application requirement. To achieve the best network performance, it is important to adapt the network operation to the application needs. We propose a middleware system for WSNs, which provides a layer between user applications and the network. Such middleware offers an automatic choice of the network configuration and data dissemination strategy

Querying Web-Sources within a Data Federation

The Web is undoubtedly the largest and most diverse repository of data, but it was not designed to offer the capabilities of traditional data base management systems – which is unfortunate. In a true data federation, all types of data sources, such as relational databases and semi-structured Web sites, could be used together. IBM WebSphere uses the “request-reply-compensate” protocol to communicate with wrappers in a data federation. This protocol expects wrappers to reply to query requests by indicating the portion of the queries they can answer. While this provides a very generic approach to data federation, it also requires the wrapper developer to deal with some of the complexities of capability considerations through custom coding. Alternative approaches based on declarative capability restrictions have been proposed in the literature, but they have not found their way into commercial systems, perhaps due to their complexity. We offer a practical middle-ground solution to querying Web-sources, using IBM’s data federation system as an example. In lieu of a two-layered architecture consisting of wrapper and source layers, we propose to move the capability declaration from the wrapper layer to a single component between the wrapper and the native data source. The advantage of this three-layered architecture is that each new Web-source only needs to register its capability with the capability-declaration component once, which saves the work of writing a new wrapper each time. Thus the inclusion of Web-sources through this mechanism can be accelerated in a way that doesn\u27t require a change in existing data federation technology

Discovering Indicators for Congestion in DBMSs

Abstract-In today's data server environments, multiple types of workloads can be present in a system simultaneously. Workloads may have different levels of business importance and unique performance goals. An autonomic workload management system controls the flow of the workloads to help the database management system (DBMS) meet the performance goals. A task of the autonomic workload management system is to prevent congestion in the DBMS, which can result in severe degradation in overall system performance. Autonomic workload management should detect that a system is becoming congested and then act to restore normal system operation. In this paper, we describe an approach to identify a set of database monitor metrics that can serve as indicators for potential congestion in a specific scenario. We present experiments to illustrate two cases of congestion in a DB2 ® DBMS and use our approach to derive the indicators