Expressing OLAP operators with the TAX XML algebra

With the rise of XML as a standard for representing business data, XML data warehouses appear as suitable solutions for Web-based decision-support applications. In this context, it is necessary to allow OLAP analyses over XML data cubes (XOLAP). Thus, XQuery extensions are needed. To help define a formal framework and allow much-needed performance optimizations on analytical queries expressed in XQuery, having an algebra at one's disposal is desirable. However, XOLAP approaches and algebras from the literature still largely rely on the relational model and/or only feature a small number of OLAP operators. In opposition, we propose in this paper to express a broad set of OLAP operators with the TAX XML algebra.Comment: in 3rd International Workshop on Database Technologies for Handling XML Information on the Web (DataX-EDBT 08), Nantes : France (2008

A Framework for Specifying and Monitoring User Tasks

Knowledge about user task execution can help systems better reason about when to interrupt users. To enable recognition and forecasting of task execution, we develop a novel framework for specifying and monitoring user task sequences. For task specification, our framework provides an XML-based language with tags inspired by regular expressions. For task monitoring, our framework provides an event handler that manages events from any instrumented application and a monitor that observes a user's transitions within and among specified tasks. The monitor supports multiple active tasks and multiple instances of the same task. The use of our framework will enable systems to consider a user's position within a task model when reasoning about when to interrupt

Web and Semantic Web Query Languages

A number of techniques have been developed to facilitate powerful data retrieval on the Web and Semantic Web. Three categories of Web query languages can be distinguished, according to the format of the data they can retrieve: XML, RDF and Topic Maps. This article introduces the spectrum of languages falling into these categories and summarises their salient aspects. The languages are introduced using common sample data and query types. Key aspects of the query languages considered are stressed in a conclusion

PQL: A Declarative Query Language over Dynamic Biological Schemata

We introduce the PQL query language (PQL) used in the GeneSeek genetic data integration project. PQL incorporates many features of query languages for semi-structured data. To this we add the ability to express metadata constraints like intended semantics and database curation approach. These constraints guide the dynamic generation of potential query plans. This allows a single query to remain relevant even in the presence of source and mediated schemas that are continually evolving, as is often the case in data integration

Experiences in teaching grid computing to advanced level students

The development of teaching materials for future software engineers is critical to the long term success of the grid. At present however there is considerable turmoil in the grid community both within the standards and the technology base underpinning these standards. In this context, it is especially challenging to develop teaching materials that have some sort of lifetime beyond the next wave of grid middleware and standards. In addition, the current way in which grid security is supported and delivered has two key problems. Firstly in the case of the UK e-Science community, scalability issues arise from a central certificate authority. Secondly, the current security mechanisms used by the grid community are not line grained enough. In this paper we outline how these issues are being addressed through the development of a grid computing module supported by an advanced authorisation infrastructure at the University of Glasgow

MDA-based ATL transformation to generate MVC 2 web models

Development and maintenance of Web application is still a complex and error-prone process. We need integrated techniques and tool support for automated generation of Web systems and a ready prescription for easy maintenance. The MDA approach proposes an architecture taking into account the development and maintenance of large and complex software. In this paper, we apply MDA approach for generating PSM from UML design to MVC 2Web implementation. That is why we have developed two meta-models handling UML class diagrams and MVC 2 Web applications, then we have to set up transformation rules. These last are expressed in ATL language. To specify the transformation rules (especially CRUD methods) we used a UML profiles. To clearly illustrate the result generated by this transformation, we converted the XMI file generated in an EMF (Eclipse Modeling Framework) model.Comment: International Journal of Computer Science & Information Technology-201