2007-02-28: Catalog Interoperability

From Datafedwiki

Catalogs are used to provide descriptions of and access to data and other web services. No single catalog serves the universal need. Multiple catalogs exist, each focusing on a particular content type or serving a particular audience. Some of their content is related and many users find content meeting their needs distributed among multiple catalogs. The ability to link catalogs so that they can share content will increase the likelihood of users discovering relevant information while minimizing the number of independent searches they need to conduct.

We focus on catalogs that generally fall under the earth science, environment, and geospatial domains. The immediate goal is to make the contents of the DataFed catalog available to other catalogs.

How can DataFed make it's services searchable by catalogs

Create FGDC metadata for each service and include in the GetCapabilties a URI to that metadata
- When a particular service is registered in a catalog, the catalog reads the GetCapabilities, is directed to the metadata, and extracts needed metadata fields.
Stand-up a Z39.50 service
Stand-up an OGC Catalog Service

Tentative approach:

Create FGDC v2 metadata files based on the DataFed metadata file
Reference metadata URI in web service GetCapabilities document
Serve metadata with either Z39.50 or OGC CSW (or RSS?)
Test interoperability with catalogs

Metadata content standards:

FGDC: http://www.fgdc.gov/metadata
- The FGDC Content Standard for Digital Geospatial Metadata - An Image Map: http://www.fgdc.gov/csdgmgraphical/index.html
ISO 19115: http://webstore.ansi.org/ansidocstore/product.asp?sku=INCITS%2FISO+19115%2D2003
- Cross-walk mapping between ISO 19115 and FGDC v2: http://www.fgdc.gov/metadata/documents/FGDC_Sections_v40.xls
- Future plans for US Profile of ISO 19115 which will become FGDCv3:http://www.fgdc.gov/standards/projects/incits-l1-standards-projects/NAP-Metadata/NAP_Metadata
  - Draft Profile: http://www.fgdc.gov/standards/projects/incits-l1-standards-projects/NAP-Metadata/napMetadataProfileV101.pdf
DIF: http://gcmd.nasa.gov/User/difguide/difman.html
SERF: http://gcmd.nasa.gov/User/serfguide/index.html
Application to DataFed
- Cross-walk mapping between ISO 19115, FGDC v2 and DataFed: http://datafedwiki.wustl.edu/images/3/3d/ISO-FGDC-METADATA-CROSSWALK-V4_DF.xls
- Example FGDC metadata file for US_SeaWiFS: http://capita.wustl.edu/SHAirED/MetaData/SeaWiFS_FGDC_DataFed.xml

Metadata exchange standards:

Z39.50: http://www.cni.org/pub/NISO/docs/Z39.50-brochure/
- Geospatial Profile for Z39.50: http://www.blueangeltech.com/standards/GeoProfile/geo22.htm
OGC Catalog Service: http://www.opengeospatial.org/standards/cat
References:
- GeoConnections Z39.50: http://www.geoconnections.org/publications/Technical_Manual/html_e/s3_ch7.html
- Lightweight Catalog: http://www.digitalearth.com.au/2006/06/23/lightweight-web-resource-catalogue/
- Metadata Mappings: http://www.ukoln.ac.uk/metadata/interoperability/
- Simplify Metadata Interface: http://mappinghacks.com/2006/09/18/have-a-nice-metadata/
- Portal Interoperability (John Evans): http://gio.gsfc.nasa.gov/docs/ESIPESGTech.ppt
- OGC Adopts ebRIM: http://www.opengeospatial.org/pressroom/pressreleases/655

Catalogs:

ESG: http://esg.gsfc.nasa.gov
GOS: http://www.geodata.gov
GCMD: http://gcmd.nasa.gov/
ECHO: http://www.echo.eos.nasa.gov/
DataFed: http://datafedwiki.wustl.edu/index.php/Compact_Catalog_-_Alphabetical

Guidance on registering services with catalogs:

ESG
GOS: http://gos2.geodata.gov/gos/metadata/CreatePublishMetadata.pdf
- Supports registration of FGDC, Z39.50
GDMD:
EECHO:

Issues:

Directory of metadata files or on-the-fly generation of metadata files or read metadata from database?
FGDCv2 or ISO 19115?
Z39.50 vs. OGC Catalog Service (does OGC CSW go ontop of Z39.50?)
Where does light weight catalogs (RSS-type) fit in the picture?

Other Implementations: