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Metainformation system CAGI

Metainformation system CAGI. Jan Ruzicka Institute of economics and system control, department GIS,VSB-Technical University Ostrava and Czech association for Geoinformation (CAGI) contact: jan.ruzicka@vsb.cz. Introduction. metadata - data about data

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Metainformation system CAGI

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  1. Metainformation system CAGI Jan Ruzicka Institute of economics and system control, department GIS,VSB-Technical University Ostrava and Czech association for Geoinformation (CAGI) contact: jan.ruzicka@vsb.cz

  2. Introduction • metadata - data about data • NCGI (National Clearinghouse for Geoinformation) - Holland • SNIG (National System for Geographic Information) - Portuguese • ESMI (European Spatial Metadata Infrastructure) - integration, global search, XML, CORBA

  3. Purpose of metainformation system CAGI • Provide information about sources of geodata in Czech Republic • Special commission for metainformation system CAGI - December 1998 • Requirements • Access through Internet - querying, viewing, input and editing metadata • using standard for metadata (CEN, ISO, national standards) • portability to many HW and SW platforms

  4. Special commission for metainformation system CAGI • Josef Hnojil - Czech Technical University in Prague • Bronislava Horakova • Stepan Kafka - District council Kutna Hora • Jan Kuranda - Universitas Carolina Prague • Milan Marencak - District council Chrudim • Stanislav Marencik - VSB - Technical university Ostrava • Jan Ruzicka - VSB - Technical university Ostrava

  5. Used standard • CEN/TC 287 • prEN 287009 Geographic Information - metadata (resp. prENV 12657 - old version of standard) • dataset (geodataset) - model of part of real world (for example: digital land model - contains groups of objects: railway, roads, forests, water, settlement; digital cadastre map - can contain groups of objects: parcel of land, owner).

  6. Data model • Based on prEN 287009 • Relational database • Discussed and changed many times • Last change had to be made after finishing pilot project • Evidence of metadata for geodataset, data of organisations, persons and literature (documentation related to dataset)

  7. Dataset • Identification (name, version, etc.) • Description (summary, spatial schema, language, etc.) • Quality elements (lineage, positional accuracy, etc.) • Related documents • Related datasets • Spatial reference system • Extent (spatial, temporal, etc.) • Content (data definition, classification) • Administrative metadata (organisations, persons, distribution) • Metadata of metadata.

  8. Development / 1 • Open, non-platform (HW and SW) dependent system • Scripting language PHP3 and SQL • PHP3-popular scripting language for building WWW applications - very well transferable • RDBMS (Relational database management system) - majority of RDBMS supported by PHP3 (for example: PostreSQL, Sybase and Oracle, ODBC (MS Access, SQL Server and Dbase)).

  9. Development / 2 • System consist of 31modules • Part of system is developed in Java • Everybody can query metadata using standard tools of WWW • Authorised users can add and edit metadata through Internet • All users can insert metadata using printed form - metadata from forms, sended by mail, administrator adds into system

  10. Pilot working • June 1999 we finished first work-version of system and system was tested by members of CAGI and other users, which had interest • After year work of pilot project (start at the beginning of 1999) • some failures in data model - dynamically removed in time of pilot project • some failures in implementation - dynamically removed in time of pilot project

  11. Inter-section commission for metadata • delegates from Ministry of Agriculture, Ministry of Environment, Ministry of the Interior, Institution for state information system and CAGI • unify metadata for geodatasets for different sections (environment, agriculture, etc.) • keeping potential possibility for exchange of metadata between sections and potential integration to ESMI project • Another changes in data model

  12. Problems • were detected by pilot project • with collecting metadata • 15 datasets, data about 26 organisations, 43 persons and 6 documents in metainformation system in 31st of March 2000 • non-interest of system services for querying metadata

  13. Causes of problems • extent of metadata • (Metadata are grouped into sections and there are three types of items in metadata specification – mandatory, optional and conditional-mandatory) • mandatory items are well hidden • complicated forms for search in system - a lot of conditions for search • average user prefers simple search (one text area) and manually search in resultant report • technical problems with host server • Connection with host server was several times out of work

  14. Problems solving • Changes in system • input of metadata better arranged - two levels of metadata input. First level contains only mandatory and conditional-mandatory items • two level search. First level - only one text item • new objects in system • projects, services, events (conferences, seminars, etc.) and application software (software which was made for specific use) • June 2000 • 21 datasets, 67 persons and 36 organisations in system • 150% increasing of connecting to the system

  15. Map Server / 1 • definition of dataset planar extent • storing geodata in RDBMS - decomposition to points • using spatial indexing - quad tree • set of programs • client part was written in Java

  16. Map Server / 2 • definition of planar extent • by selection of administrative parts of Czech republic (regions, districts, etc.) • by selection of map lists • by sending breakage points co-ordinates or by drawing user-defined polygon in client part of map server • show planar extent of dataset • allows search for datasets by extent • User can click into raster map (not in Java) and search for datasets, which have planar extent in point of user click

  17. Map Server / 3

  18. XML • Inter-section commission for metadata -specification for exchange format of metadata • base for development of DTD (document type declaration) for XML documents • DTD is framework for building XML documents • system is able create XML documents • for core metadata (mandatory and conditional-mandatory items) of datasets • planning exchange metadata between metainformation systems of different sections

  19. References • www.cagi.cz - CAGI • gis.vsb.cz/midas - metainformation system CAGI • jan.ruzicka@vsb.cz - administrator of metainformation system CAGI

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