David Howie Marwick

A Model for Query Decomposition and Answer Construction inHeterogeneous Distributed Database Systems

The problem of retrieving information from a collection of heterogeneous distributed databases has attracted a number of solutions. However, the task of integrating established database systems is complicated not only by the differences between the database systems themselves, but also by the differences in structure and semantics of the information contained within them. The problem is exacerbated when one needs to provide access to such a system for naive end-users.This paper is concerned with a Knowledge-Based Systems approach to solving this problem for clearly bounded situations, in which both the domain and the types of query are constrained. At the user interface, dialogue is conducted in terms of concepts with which the user is familiar, and these are then mapped into appropriate database queries. To achieve this a model for query decomposition and answer construction has been used. This model is based around the development of an Intensional Structure containing information necessary for the recapture of semantic information lost in the query decomposition process and required in the answer construction process. The model has been successfully implemented in combination with an embedded KBS, within a five-layer representation model.

Developing a regional healthcare information network

The Internet and associated technology is transforming the dissemination of healthcare information. As this occurs, means must be developed to manage and coordinate it effectively. One approach is through community healthcare information networks (CHINs), which benefit both information providers and consumers. The paper reports on a regional CHIN operational in Scotland.

A framework and test-suite for assessing approaches to resolving heterogeneity in distributed databases

Abstract The problem of connecting together a number of different databases to produce an integrated information system has attracted a considerable amount of attention over the years and various approaches have been developed to handle this. However, the general problem of gathering related information from a number of existing heterogeneous databases is complex because of the differences in representation and meaning of data in different data sets. Many different approaches have been described to resolve this problem, and some prototype systems built. However, it is difficult to compare the effectiveness of different approaches and prototypes. This paper is aimed at addressing the specific issue of assessing the generality of different approaches. To this end it presents a framework for classifying the differences between data in different databases and a test-suite which can be used to evaluate and compare the extent to which different approaches handle different aspects of this heterogeneity.

Using a Distributed Approach to Retrieve and Integrate Information from Heterogeneous Distributed Databases

With the current explosion of information accessible through the Internet, there is increasing interest in the problem of retrieval and integration of information from heterogeneous data sources. Much work has been done in this area, although aspects of the problem remain. This paper describes a general approach, which uses an agent-based architecture to retrieve information from a set of heterogeneous distributed databases and consolidate it, taking account of the syntactic and semantic differences between data sources. The system has been implemented in Java and makes use of CORBA, XML and JDBC.

Dynamic Information Presentation through Web-based Personalisation and Adaptation — An Initial Review

Personalisation and adaptation of information and information presentation to reflect user needs and interests is an area in which there is considerable interest. DIP, Dynamic Information Presentation, is a research project that focuses on problems in this area. As part of this research a review has been conducted of existing Web-based information applications from a variety of domains that use such techniques, and a set of dimensions proposed as a basis for analysing andcomparing them. The applications fall naturally into three categories. The results provide a useful step towards a general framework for classifying these approaches.

A toolkit for creating personalized presentations

With the explosion in the availability of information online, users are finding it increasingly difficult to track down the specific material that they require. Users are therefore becoming increasingly dependent on intelligent services to provide information that is dynamically selected and presented according to their preferences. However, development of these personalized services is not trivial. Significant effort is required in terms of engineering the underlying knowledge that is used by a service to determine which information might be relevant to a particular user and how to present it. A Toolkit that reduces the complexity involved in the creation and maintenance of such services is discussed.

Data placement in a parallel DBMS with multiple disks

Abstract Various strategies have been developed to assist in determining an effective data placement for a parallel database system. However, little work has been done on assessing the relative performance obtained from different strategies. This paper studies the effects of different data placement strategies on a shared-nothing parallel relational database system when the number of disks attached to each node is varied. Three representative strategies have been used for the study and the performance of the resulting configuration has been assessed in the context of the TPC–C benchmark running on a specific parallel system. Results show an increase in sensitivity to data placement strategy with increasing number of disks per node.

Describing the MIPS multimedia presentation system with the IMMPS reference model

The MIPS system retrieves information from a set of distributed heterogeneous information sources as a result of a single query, and generates an integrated hypermedia presentation of the answer. The retrieval and presentation processes in the MIPS architecture are described firstly using the structure of the original authors, and then in the terminology and structure of the IMMPS reference model. The reference model was developed to address the intelligent generation of multimedia presentations, but it can also be used to describe systems where the presentation structure is generated automatically but where the content is retrieved rather than generated. The mapping from the generation to retrieval processes within the IMMPS reference model is considered.

An experimental consideration of the use of the Transrelational TM Model for data warehousing

In recent years there has been a growing interest in the research community in the utilisation of alternative data models that abandon the relational record storage and manipulation structure. The authors have already reported experimental considerations of the behavior of Relational, Binary Relational and Associative models within the context of Data Warehousing, to address issues of storage efficiency and combinatorial explosion through data repetition. In this paper we present an implementation of the TransrelationalTM model, based on the public domain definition provided by C.J. Date, which we believe to be the first reported instantiation of the model. Following the presentation of the implementation, we also present the results of performance tests utilising a set of metrics for Data Warehouse environments, which are compared against a traditional N-ary Relational implementation. The experiment is based on the standard and widely-accepted TPC-H data set.

Constraining XML transformations for personalised information presentation

Through the use of different stylesheets it is possible to transform the information contained in XML documents and present it in different ways, for example to create personalised presentations. However, in doing so there is a danger that the transformation may result in a presentation, which fails to carry the essential message intended by the provider of the source document. We believe that the Information Provider should be able to provide constraints on permitted transformations of their document, stating for example which elements are mandatory, which must not be changed, which must have the order preserved. This paper discusses the need for such transformation constraints, and proposes a simple metadata annotation expressing the required constraints. We consider the adequacy of the proposed approach, and alternative ways to constrain transformations.