In the multimedia field, metadata are becoming increasingly important for efficiently cataloguing the abundant flood of information. (Metadata are data on information structures.) The number of electronic data files made accessible by metadata increases rapidly, however at the present retrieving textual, audio, video and/or mixed data files through metadata is definitely restricted. In particular, there is only a limited number of metadata formats at hand. Nevertheless, within the framework of testbeds, some efforts have been made not only to develop retrieval systems adjusted to the respective field of application, but also to unite several metadata formats into one system in order to obtain better search results. This paper describes specifications for developing an attribute service which, as part of the "Dragon Slayer" distributed file system, is intended to offer a uniform platform for different metadata formats, and to offer efficient information metadata retrieval. Via the interface provided by the Dragon Slayer file system, the user can assign metadata to files and reference them via these metadata. For each metadata format used, an external meta module is incorporated into the file system which, depending on its format, manages and searches for metadata in a database, according to their format.

A universal framework for managing metadata in the distributed Dragon Slayer system

Automating geospatial metadata generation-An integrated data management and documentation approach

This paper proposes a prototype for integration and visualization of geo-referenced information (GRI) in a distributed environment in general and World Wide Web in particular. This prototype adopts a three-tier architecture and includes three main components: GRI wrapper for distributed GRI web sites, GRI integration mediator and client side visualization interface.In this prototype, XML is used as a communication protocol between distributed web sites that provide GRI and the mediator, and between the mediator and clients. Java Servlets are written to translate data in distributed websites into XML documents. Data in distributed websites can be stored in a flat file, relational database, object-oriented database or object-relational database. Java Servlet in the mediator server retrieves data from related distributed websites in an XML format upon a request from the client side, parses the retrieved XML documents, performs merge or other operations on the retrieved XML documents to build a new XML document and sends it to the client side. When the client side gets the requested data from the mediator server, it will parse the returned XML document and draw it inside the browser window by using a Java applet.

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Prototype for wrapping and visualizing geo-referenced data in a distributed environment using XML technology

Search interfaces for data discovery are essential in the context of a Geospatial Data Infrastructure. This paper discusses the development of a search interface, aimed at effective searches and an integration of a catalogue function and thematic mapping. For this purpose, the Resources Description Framework (RDF) is used to store the summaries of metadata of geospatial contents. These summaries are indexed based on their topics. Their topic categories are expressed using the RDF schema. The RDF queries and the transformation of results play a prominent role in the visualization of search results as a table, a thumbnail, and a bull's-eye display with possibilities to project footprints of results on top of a basic map and thematic layers. To highlight their matches to the search terms, the Hausdorff distance and the closeness degree were applied respectively to determine the geographic and thematic relevance. Feedback from participants testing the prototype indicated the benefits of the table and thumbnail displays as well as the possibility to combine these displays with metadata and thematic mapping for data discovery. The feedback also confirmed some design challenges in the depictions of relevance and symbolization of metadata.

A Search Interface for an SDI: Implementation and Evaluation of Metadata Visualization Strategies

Integration of multiple heterogeneous data sources continues to be a critical problem for many application domains and a challenge for researchers world-wide. One aspect of integration is the translation of schema and data across data model boundaries. Researchers in the past have looked at both customized algorithmic approaches as well as generic meta-modeling approaches as viable solutions. We now take the meta-modeling approach the next step-forward. In this paper we propose a flexible, extensible and re-usable transformation modeling framework which allows users to (1) model their transformations; (2) to choose from a set of possible execution strategies to translate the underlying schema and data; and (3) to access and re-use a library of transformation generators. In this paper we present the core of our modeling framework - a set of cross algebra operators that covers the class of linear transformations, and two different techniques of composing these operators into larger transformation expressions. We also present an evaluation strategy to execute the modeled transformation, and thereby transform the input schema and data into the target schema and data assuming that data model wrappers are provided for each data model. The proposed framework has been implemented, and we give an overview of this prototype system.

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Gangam: a transformation modeling framework

1. ABSTRACT This paper describes development of meta databases for geospatial data in the WWW in general as well as efforts/activities in the context of developing InGeoMDB (InG eoForum Meta Data Base). Hence, especially existing metadata standards wiIl be analysed and evaluated. Furthermore possibilities of integrating meta databases into metadata information systems (MIS) resp. catalogue systems (CS) will be pointed out as well as apsects, which should be considered with regard to ‘Information Retrieval’ via MIS/C S in the world wide web. 1.1

Karen Lutze

Papers

Development of meta databases for geospatial data in the WWW