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Harvesting Metadata for Use by the geodata Portal

Harvesting Metadata for Use by the geodata.gov Portal. Doug Nebert FGDC Secretariat Geospatial One-Stop Team. NSDI: a Foundation for GOS. Geospatial One-Stop (GOS) implements the principles of the NSDI spelled out in Executive Order 12906 (recently revised)

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Harvesting Metadata for Use by the geodata Portal

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  1. Harvesting Metadata for Use by the geodata.gov Portal Doug Nebert FGDC Secretariat Geospatial One-Stop Team

  2. NSDI: a Foundation for GOS • Geospatial One-Stop (GOS) implements the principles of the NSDI spelled out in Executive Order 12906 (recently revised) • GOS builds on the resources already available in the NSDI – FGDC and endorsed external Framework Standards, NSDI Clearinghouse Network • Operated as project coordinated through FGDC Secretariat with many agency partners

  3. Geodata.gov and the NSDI Clearinghouse • Over 150 collections of metadata exist within searchable NSDI Clearinghouse Nodes in the US • All FGDC metadata records are searchable by fields and full-text through six replicated search gateways • geodata.gov will speed and simplify search and browse of these and other metadata through its portal interface

  4. GOS Expectations of Portal • Search for geospatial data is 'easy-to-use‘ and would replace the primary search facilities of the NSDI Clearinghouse Gateways • Metadata are harvested from remote collections into a single metadatabase • Browsing for geospatial data is made possible through common ISO Categories and resource type assignments • Descriptions of map and data services are also indexed from FGDC metadata entries • Data descriptions are linked to an online map viewer where map services exist

  5. Portal at geodata.gov • Initial release of the GOS portal is online with startup content selectively gathered from key providers and entered ‘by hand’ • New content will be harvested from the Web or individual metadata files may be uploaded as XML or via form input • OGC Web Map Services (WMS) and ArcIMS ‘image’ services supported in viewer • Data, map services, static maps, and applications are among the resource types indexed

  6. Current Publication Options • Users may contribute metadata one of three ways: • Enter FGDC metadata into a form at geodata.gov and they are stored and indexed there • Upload metadata as FGDC XML to the geodata.gov site • Register their existing metadata collection to be harvested into the GOS metadata repository

  7. metadata metadata metadata metadata form entry XML upload search map services data data metadata cache geodata.gov map viewer data data

  8. Harvesting capabilities • Harvesting is a scheduled retrieval of metadata from a remote collection, such as an existing Clearinghouse Node • The harvester detects new content and brings it into a metadata ‘cache’ at geodata.gov for inclusion in search • Scheduling can be established in the registration profile of each provider

  9. Harvesting options • A provider wanting to have content harvested into in geodata.gov can register: • Z39.50 “GEO” Metadata server (NSDI Clearinghouse Node) • ArcIMS Metadata Server • OAI-PMH (Open Archives Initiative, Protocol for Metadata Harvest) • Web Accessible Folder

  10. Publishing content to geodata.gov geodata.gov Schedule/ registry Metadata OAI-PMH Service Metadata harvester Metadata ArcIMS Service Metadata Z39.50 Service validation XML Web folder no ok reject/ inform yes V A L I D A T E Entry Form GOS Metadata cache GOS Subset Repository XML XML upload Search interface yes no reject/ inform ok

  11. Portal expectations on metadata • GOS Portal requires tagging of metadata content using the ISO 19115 Category values for browse and search assistance • Collections must also be tagged as to the provider scope (Federal, State, Local, Commercial, Academic, etc) • Online Linkage field is used to store links to OGC Web Mapping Services or (soon) ArcIMS image services or to dataset-specific download/ordering page

  12. Suggested Resolution • Metadata collections will be registered with the Portal along with: • Related service information pulled from Clearinghouse Registry, where available • Reference to an ISO Category mapping table to translate Theme Keyword values to Category equivalents – or add ISO Category as a controlled vocabulary in existing metadata • Classification as to Provider type

  13. Automated Tagging • The following tag values will be derived from the FGDC metadata and stored in the metadata cache at geodata.gov: • Geographic extent (Global, National, Regional, Local) will be determined by the area referenced in the Bounding Coordinates • Resource type will be determined heuristically from the Geospatial Data Presentation Form and clues in the Online_Linkage and Resource_Linkage URLs • Specific guidance will be given to providers

  14. To participate in One-Stop: • Provide FGDC XML form of CSDGM V2 (1998) or ISO 19139 • Areas to focus on: • Assure minimum mandatories (pass mp as best you can) • Populate online_linkage with valid URL to the data being described • Fix dates (use Metadata_Date to reflect metadata changes) • Review content of text fields • Select publishing method (XML upload, form, harvest of Z39.50, ArcIMS, Web, or OAI) • If a collection is to be harvested: • Develop a mapping table of Theme Keywords to ISO Category values – or add ISO Categories into metadata • Register collection with GOS Portal

  15. Who is being test-harvested? • Z39.50: • NOAA Coastal Services Center • Alamo Area COG • FEMA Multi-hazard Mapping Initiative • Alaska Geospatial Data Clearinghouse • ArcIMS: • Oregon State University • New Jersey Office of GIS

  16. How can Z39.50 Nodes participate in geodata.gov? • Update your Z39.50 software to allow: • Query on “Metadata Date” as date-last-modified • Retrieval of each metadata record by a unique and persistent ID • Build a mapping table from local theme keywords to ISO Categories • Register your collection with geodata.gov and schedule your harvest

  17. Alternatives to Z39.50 • ArcIMS Metadata Server can be harvested using ‘native’ AXL requests – just register your Metadata Server • If you don’t have a metadata service (ArcIMS+SDE or Z39.50) consider creating a Web-accessible folder that allows directory browsing, then register its existence with geodata.gov

  18. What's Next? • GOS Team is refining harvesting and publishing services to more automatically process remote metadata • FGDC staff will enhance testing tools and perform audits and metadata counseling to improve metadata content • Guidance will be provided as to how to construct the mappings from local Theme Keywords to ISO Categories • Instructions on setting up registered Web Folders and OAI-PMH providers to follow

  19. Interface Enhancements • Clarify the options for publishing (XML upload, form entry, collection via Z39.50, OAI, web folders) • Clarify the search and display modes of the interface • Display search results rectangle on map • Elimination of the Primary/Secondary/Tertiary classification in favor of more legible and derivable resource types • Allow discovery and loading of a single layer (not all layers from a service by default)

  20. Research Topics for FY 2004 • Following USGS example, evaluate spatial ranking to improve geographic relevance of results • Provide developers with technical information on how applications can connect to catalog, data access, and mapping services identified through GOS • Register geodata.gov organizations and services to the public UDDI as another method to promote GOS resources • Investigate a common thematic thesaurus for GOS/NSDI use • Implement transition strategy from FGDC to full ISO 19115 metadata

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