Ralf Kramer

Thesaurus federations: loosely integrated thesauri for document retrieval in networks based on Internet technologies

Abstract As a result of the distribution of interrelated information over several different information systems, the interconnection of information systems has increased in recent years. However, a purely technical interconnection is insufficient for users who need to find their way to information they are looking for. Thesauri are a proven means to identify documents, e.g., books of interest in a library. For different domains, different thesauri are available, which can be used in information systems as well, e.g., for the indexing and retrieval of data objects. Thus, the interconnection of information systems raises the need to integrate related thesauri. Furthermore, recent advances in open interoperability technologies (World Wide Web, CORBA, and Java) offer the potential for completely new technical solutions for employing thesauri.This paper presents an approach for integrating multiple thesaurus databases. It concentrates on the integration of distributed and heterogeneous thesaurus databases and the integration of multilingual and monolingual thesauri. The software architecture takes advantage of the most advanced Internet and CORBA technology currently available in public domain and in commercial implementations.

WWW-UDK: a web-based environmental meta-information system

The environmental data catalogue Umweltdatenkatalog UDK is a standard meta-information system for environmental data for use by state authorities and the public. Technically, the UDK consists of a database together with a front-end tailored to the needs of environmental specialists. FZIs contribution has been to develop a front-end that makes the UDK database available using the tools and techniques of the World-Wide Web. Among the features of WWW-UDK are several query modes for the UDK objects and addresses, an environmental thesaurus, on-line access to some of the underlying data (e.g., databases and environmental reports), multilingual query and result forms, and an on-line help system. Currently, several installations of WWW-UDK are used in Austria and in Germany on the Internet and on Intranets. WWW-UDK can be easily integrated into a federation architecture which is based on CORBA, WWW, and Java.

Active information delivery in a CORBA-based distributed information system

Many application areas require the integration of heterogeneous information sources into a coherent distributed information system. With such systems, users frequently need not only be able to access information, but they also have to be notified automatically when new information that is relevant to their work becomes available. For example, an our environmental systems project, a civil servant needs to be informed when a measured air quality parameter exceeds a certain threshhold. Detection of such a critical situation requires subsequent monitoring of several data sources (e.g., a database recording measurement values and a database with limit values). The paper presents an approach for such situation monitoring which is based on CORBA, for the technical integration of heterogeneous systems and on active DBMS-style ECA-rules. In particular, it discusses how ECA-rules can be adopted in a CORBA environment, and describes a CORBA-based system for situation monitoring. The major implementation issues addressed are event detection within autonomous component systems and detection of complex distributed situations.

Databases on the Web: technologies for federation architectures and case studies

The Internet and especially the World-Wide Web (WWW) provide a promising approach to make all kinds of data and information available on both the Internet and on private networks, so-called Intranets. However, making information available as static pages that are written in the Hypertext Markup Language (HTML), is not suited for the great body of data that already resides in database management systems (DBMS) for several reasons. Potentially huge data volumes must be managed twice, data updates are difficult to handle, and search facilities are limited. Another limitation is that standard WWW technology does not allow to combine partial results from different servers in a single result page. The restrictions sketched above become more and more

Global Access to Environmental Information

Environmental applications deal with huge numbers of knowledge domains. In order to cope with the increasing number of highly diverse data and information sources, explicit modelling of meta-data is mandatory. This paper focuses on how data in an existing meta-data model, originally developed for German authorities, can be accessed in wide-area networks. The current implementation combines navigational access methods via Mosaic and declarative access through SQL. The system architecture and query processing in that architecture are described. Lessons learned from the initial system concern the necessity for design recovery when using an existing meta-data model and experiences obtained from using the stateless World-Wide Web (WWW) environment in database applications. Looking ahead, we sketch the active information system that will support access to semantically heterogeneous information sources in the future.

Design and implementation of KARDAMOM - a set - oriented data flow database machine

Recently, several proposals for multiprocessor database machines have emerged. Most approaches focus upon the solution of the I/O-bottleneck or upon parallel algorithms for relational operations. Other crucial issues in such systems include communication between the software modules of the database management system which are distributed across the processors and efficient control of parallel query execution. In this paper, we argue that strictly set-oriented query execution and data flow control are appropriate mechanisms in order to minimize overheads for communication and control of execution. Then we give an overview of the design of the multiprocessor database machine KARDAMOM which integrates both concepts. An important feature is a two-level system architecture, where the upper level consists of those parts of the system which operate exclusively on tuple sets instead of pages. A dedicated storage manager is proposed which provides a uniform interface for the representation of tuple sets as well as for the exchange of tuple sets between different system components. Other important issues are related to query translation and optimization and to transaction management in a set-oriented environment.

Thesaurus federations: a framework for the flexible integration of heterogeneous, autonomous thesauri

Modern information systems such as the World Wide Web and digital libraries contain more data than ever before, are globally distributed, are easy to use, and therefore become accessible to huge, heterogeneous user groups. On the other hand, the potentially enormously large amount of heterogeneous information requires powerful tools to allow the user to find relevant pieces of data. One such tool is thesauri. They are a proven means to provide a uniform and consistent vocabulary for the indexing and retrieval of information-bearing objects (IBOs). Modern multi-lingual and multi-subject information systems require more than the traditional single-language, narrow-focus thesauri. The broad clientele of information systems demands thesauri that can be used by non-specialists. To achieve this goal, we introduce the framework of thesaurus federations, i.e. loose compounds of distributed, multi- or mono-lingual thesauri that go beyond the already-known concepts of multi-thesaurus systems. We classify multi-thesaurus systems into multi-thesaurus environments, thesaurus switching systems and thesaurus compounds. Our architecture is based on a mediation layer and wrappers for the integration of heterogeneous, distributed thesauri. We present a Java-based prototype system which enables integrated access to several thesauri, which is available through a SQL or HTML interface via a comfortable thesaurus federation browser. This system has been used for the retrieval of metadata records managed by the Catalogue of Data Sources of the European Environment Agency (EEA).

Limits database for an environmental information system

This paper describes the design and implementation of the limits database for the environmental information system of Baden-Wurttemberg. Environmental legislation in Germany is based on numerous laws, decrees, and other regulations. Regulations of the European Union (EU) have a growing impact. Not surprisingly, terminology differs substantially among different regulations. Even for experts, it is impossible to keep track of all regulations and their specific terminology. Thus, two main problems had to be solved. The first challenge was to develop a conceptual model that captures the semantics of a broad collection of regulations. The second main requirement was to support (possibly non-expert) users in querying the limits database. Both challenges are met by an approach that can be characterized as a. front-end to a conventional, state-of-the-art relational database system that accepts and processes fuzzy queries.

Poster on accept heterogeneity: an event monitoring service for CORBA-based heterogeneous information systems

Summary form only given. Todays distributed information systems often are collections of existing information sources and as such heterogeneous. Technical integration of heterogeneous sources is supported by CORBA. However, CORBA provides very general support and does not take source specific semantics into account. This also applies to CORBAs Event Service. Our objective is to enhance CORBA by mechanisms that allow to add application semantics. Our key idea is to provide a flexible configurable event monitoring service, which accepts heterogeneity, for a CORBA environment. Configurable means that we are able to generate code templates at compile time and to provide dynamic parametrization of parts of the service. Event passing semantics follow those developed for active database Event-Condition-Action (ECA) rules.

Quality of service transferred to information retrieval: the adaptive information retrieval system

Users often quit an information retrieval system (IR system) very frustrated, because they cannot find the information matching their information needs. We have identified the following two main reasons: too high expectations and wrong use of the system. Our approach which addresses both issues is based on the transfer of the concept of Quality of Service to IR systems: The user first negotiates the retrieval success rates with the IR system, so he knows what to expect from the system in advance. Second, by dynamic adaptation to the retrieval context, the IR system tries to improve the users queries and thereby tries to exploit the underlying information source as best as possible.