Web Catalog Service

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A Web Catalog Service ( WCAS ), also known as Catalog Service for the Web ( CSW ), is the Internet-based publication of information about geospatial applications , geospatial services and geodata (metadata) in a geodata infrastructure . It is important that this service itself does not contain any geodata, but only descriptive metadata of the same. This geospatial service was specified by the Open Geospatial Consortium (OGC) and published under version 2.0.0. The corresponding application profile is available for download free of charge. The managed metadata is coded according to the standards ISO 19115 (for geospatial applications and geodata) and ISO 19119 (for geospatial services). The CSW has the processing modes selection (Discovery), continuation (Transaction) and harvesting (Harvesting). The Catalog Service is of particular importance due to the EC INSPIRE directive .

selection

This mode is supported by the GetCapabilities, DescribeRecord, GetRecords and GetRecordById operations. The selection is carried out by the metadata information systems (GeoMIS) of the spatial data infrastructures in order to provide a customer with information about spatial applications, spatial services or spatial data. A GeoMIS is often an application within a geoportal .

According to the CSW standard 2.0.2, the selection is a function that must be implemented in order to comply with the standard.

Continuation

This mode is supported by the Transaction operation. This enables metadata documents to be inserted (Insert), updated (Update) or removed (Delete) from the catalog. The process is continued via - Internet-based - metadata editors. However, the operation is probably not made freely available on the Internet by catalog providers.

The continuation is an optional function according to the CSW standard 2.0.2. It doesn't have to, but it can be implemented.

harvest

This mode is supported by the harvestResource operation. This operation is used to transfer the metadata from an external catalog service (CSW) to your own. This is done cyclically by a common point (office and / or coordination point) in a spatial data infrastructure. The federal states in Germany harvest the local, regional or nationwide catalogs and offer their customers a centralized search option. The national catalog in the GeoPortal.Bund is not based on the harvest mode. He himself uses the selection mode for all nationwide subject-neutral and nationwide subject-specific catalogs for his research. Harvesting metadata has the disadvantage that recursions of linked catalog services can result in multiple entries.

According to the CSW standard 2.0.2, the harvest is an optional function. It doesn't have to, but it can be implemented.

See also

Web links

CSW directories