Catalog Term Definitions

Services

A service represents a place where data is stored and can be retrieved.

Service Provider

The federal partner or regional association responsible for hosting and providing the data. Also known as a data provider.

Service Type

• DAP (Data Access Protocol) - An implementation of the OPeNDAP standard. This service type transmits data in a format very similar to NetCDF and is widely adopted for hosting and sharing NetCDF datasets.
• WMS (Web Map Service) - An OGC protocol for serving georeferenced map images over the internet. The images are generated from a reference dataset, typically gridded datasets.
• WCS (Web Coverage Service) - An OGC protocol used for the serving of geospatial information.
• SOS (Sensor Observation Service) - The Sensor Observation Service (SOS) is a web service to query real-time sensor data and sensor data time series and is part of the Sensor Web.

Service Name

The service name is the human readable name to identify the service. Generally the names are intuitive as to what kind of data the particular service provides.

Where it comes from

Here's an example service defined in Geoportal:

Directional wave and sea surface temperature measurements collected in situ by Datawell Waverider buoy located near FAREHAM, ST. CROIX, VI from 2010/06/29 to 2011/04/13.

Here's the bit that defines the Service Name

  <gmd:identificationInfo>
    <gmd:MD_DataIdentification id="DataIdentification">
      <gmd:citation>
        <gmd:CI_Citation>
          <gmd:title>
            <gco:CharacterString>Directional wave and sea surface temperature measurements collected in situ by Datawell Waverider buoy located near FAREHAM, ST. CROIX, VI from 2010/06/29 to 2011/04/13.</gco:CharacterString>
          </gmd:title>
          <gmd:date>

Here's the XPath:

/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:citation/gmd:CI_Citation/gmd:title/gco:CharacterString

Service ID

The service id uniquely identifies a specific service for the hosting service provider. This is useful in assiting data providers with a meaningful key by which to identify a particular service.

Where it comes from

Looking at the SLDMB Buoy 43500 Aggregated Sea Surface Temperatures service and the appropriate catalog entry; we collect the service ID from the NGDC geoportal metadata catalog.

Here's the big that defines the Service ID

<gmd:fileIdentifier>
    <gco:CharacterString>buoy43500-agg</gco:CharacterString>
</gmd:fileIdentifier>

Here's the XPath:

/gmd:fileIdentifier/gco:CharacterString

Data Access URL

The URL clients use to connect with and access the data.

Data Info URL

Some datasets provide their own presentation of the datasets and this is the URL for that presentation.

Source Metadata URL

If there's a URL provided in the catalog for harvesting additional metadata we include it in the services page.

Indexing a Service

Once a day we crawl through the NGDC Geoportal Catalog and get the catalog entries for the service providers we're interested in: namely the IOOS participants.

Datasets

A set of information that is available for download of inspection. The information generally contains scientific parameters are provide merit to oceanographic, climatological and meteorological investigations and studies.

Name

The dataset name is a general title used to identify and classify the data contained within the dataset.

Where it ocmes from

For DAP it comes from the global attribute title

For SOS it comes from the station identifier.

Coverage

The coverage is a visual representation of the geospatial extents of the data in the region of North America.

Metadata NCML

NCML is the netCDF-Java Markup Language and is a way to represent the metadata contents of a netCDF dataset in the extensible markup language (XML).

Harvesting

Once a day we go through all of the services that we are cataloging and make useful requests to the datasets they provide. Generally what we're looking for when we harvest are the geospatial bounds, metadata updates, and track information for gliders.

Harvest Status

There are a variety of reasons for why we are unable to get information about a dataset.

Harvest Status	Explanation
Service is Down	A connection with the service could not be established
Timed Out	Getting the data took too long
Permission Denied	The URL provided results in an HTTP 403 which indicates that clients don't have permissions to view the resource
Not Found	The URL provided results in an HTTP 404, which indicates that the resource requested doesn't exist
Invalid SOS	The XML response from an SOS service can not be parsed either due to a syntax error or an illegal character
Harvest Failed	The harvest failed to execute for a reason not specified above. We log the errors that happen and try to resolve them the best we can.

Harvest Success Rate

An indicator used to identify the rate of availability for a particular service. This number is generally represented as a fraction: the number of successes over the number of attempts.