USGIN ISO metadata profile

The USGIN project has drafted and is using a specification for use of ISO 19115/19/39 metadata, recommendations for simple metadata content, and a proposal for a URI scheme to identify resources using resolvable http URI's(see http://lab.usgin.org/usgin-profiles). The principal target use case is a catalog in which resources can be registered and described by data providers for discovery by users. We are currently using the ESRI Geoportal (Open Source), with configuration files for the USGIN profile. The metadata offered by the catalog must provide sufficient content to guide search engines to locate requested resources, to describe the resource content, provenance, and quality so users can determine if the resource will serve for intended usage, and finally to enable human users and sofware clients to obtain or access the resource. In order to achieve an operational federated catalog system, provisions in the ISO specification must be restricted and usage clarified to reduce the heterogeneity of 'standard' metadata and service implementations such that a single client can search against different catalogs, and the metadata returned by catalogs can be parsed reliably to locate required information. Usage of the complex ISO 19139 XML schema allows for a great deal of structured metadata content, but the heterogenity in approaches to content encoding has hampered development of sophisticated client software that can take advantage of the rich metadata; the lack of such clients in turn reduces motivation for metadata producers to produce content-rich metadata. If the only significant use of the detailed, structured metadata is to format into text for people to read, then the detailed information could be put in free text elements and be just as useful. In order for complex metadata encoding and content to be useful, there must be clear and unambiguous conventions on the encoding that are utilized by the community that wishes to take advantage of advanced metadata content. The use cases for the detailed content must be well understood, and the degree of metadata complexity should be determined by requirements for those use cases. The ISO standard provides sufficient flexibility that relatively simple metadata records can be created that will serve for text-indexed search/discovery, resource evaluation by a user reading text content from the metadata, and access to the resource via http, ftp, or well-known service protocols (e.g. Thredds; OGC WMS, WFS, WCS).