Metainformation system CAGI
Jan RuzickaJan Ruzicka
Institute of economics and system control, Institute of economics and system control, department GIS,VSB-Technical University Ostravadepartment GIS,VSB-Technical University Ostrava
and and
Czech association for Geoinformation (CAGI)Czech association for Geoinformation (CAGI)
contact: [email protected]: [email protected]
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
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
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
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).
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)
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.
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)).
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
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
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
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
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
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
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
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
Map Server / 3
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
References
• www.cagi.cz - CAGI
• gis.vsb.cz/midas - metainformation system CAGI
• [email protected] - administrator of metainformation system CAGI
