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Expanding Data Sharing with Metadata Services
Continued...

Scenario 3: "Access to particular name-value pairs [of metadata elements] related to the feature is both necessary and available."

Metadata Services require that certain elements (and specific values, if desired) be present in the metadata for publication of the dataset. The metadata is validated on these required fields, and only metadata documents that pass the validation process are published.

Scenario 4: "To accelerate a query on the data (that is, one is using an index to data where the index is contained in metadata)."

By default, Metadata Services index the contents of documents during the publication process to enable faster searches. To speed up the publishing process, indexing can be turned off during the publication process and indexing performed as a batch process offline prior to publication.

Scenario 5: "Application servers have a preferred set of information sources [that] have been 'pre-certified' [and] their 'fitness' is already ensured."

Database administrators have the option of associating custom parameters with each published dataset, precertifying it to a set of preferred information sources.

Scenario 6: "Querying metadata to determine whether there is a market for some (new) data."

Metadata Services queries that do not yield many results can be used to identify underserved sectors of data markets.

Scenario 7: "Decide on how to produce and/or market an information product or information service."

Queries of existing data can also provide information about the type of data desired by the market. This information can be useful in marketing existing datasets and developing new datasets.

Scenario 8: "Design a metadata profile for a specific discipline, for a specific service, for a specific information community, or for a specific series of geospatial information products."

Because Metadata Services clients are fully customizable, they can be tailored to different data content standards; be used to search by the data types, themes, or keywords used by specific industries or disciplines; and perform custom searches by geographic location.

Scenario 9: "Changing metadata values and data dictionary entries to another (natural) language or to a new discipline by mapping to numeric equivalents of metadata entries and looking up the corresponding values in a 'book of equivalencies'."

The out-of-the-box Metadata Services comply with FGDC and ISO standards. The ISO standard specifies searchable values by numerical values. The final display values are lookup strings that can be translated into any language.

Scenario 10: "Modifying a metadata profile in order to allow a specific discipline to evolve its metadata."

Metadata Services can display information from any content published to it. Once a dataset has been published, updates to the metadata can be authored on a local machine and republished to the server, overwriting old information with new.

Scenario 11: "Using certain metadata to exploit the related feature data in the context of a specific mathematical model…Thinking mostly about image exploitation, where the metadata includes the parameters that are specific to a particular image geometry model, or to a specific image accuracy model."

Metadata can describe any kind of information about the dataset because the content of the metadata document is invisible to the server. For example, metadata for raster images could include pixel counts, resolution, or grid size.

Web Map Services

The OGC's Web Map Server (WMS) specification standardizes the way Web maps are requested. OGC conformance for WMS has not yet been defined. However, Metadata Services support the specification for this service. The Metadata Explorer can display published WMS services that are returned as matches to a query. For each service, one can view the metadata for the service, view the associated map with the ability to pan and zoom, and discover parameters such as the server hosting the map service.

Summary

Metadata Services enable the creation of an online, central repository of metadata for data sharing and easy data access. In large part due to the format of the stored metadata, XML, Metadata Services can adhere to any content standard, are highly customizable and fully interoperable, support internationalization, and conform to OGC standards.

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