18 Copyright © 2012 Open Geospatial Consortium.
8.3.1 DescribeCoverage request
The DescribeCoverage request structure is derived from RequestBase, extended with a non-empty list of coverage identifiers. This structure is shown in 7 and Table 11.
Requirement 18 reqcoredescribeCoverage-request-structure: A DescribeCoverage request shall consist of a data structure as defined in 7 and Table 11.
The concrete representation of this structure depends on the protocol binding chosen.
Requirement 19 reqcoredescribeCoverage-valid-identifier: Each coverage identifier in the list submitted in a DescribeCoverage request shall identify an
OfferedCoverage object available on the server addressed.
8.3.2 DescribeCoverage response
The response to a successful DescribeCoverage request contains a list of coverage metadata, one for each coverage identifier passed in the request.
Requirement 20 reqcoredescribeCoverage-response-structure: The response to a successful DescribeCoverage request shall consist of a CoverageDe-
scriptions element as described in Figure 8, Table 12, Table 13, and Table 14.
class DescribeCov erage
«Data Type»
DescribeCov erage
+ coverageId: NCName [1..] «Data Type»
RequestBase
+ section: String = All + service: string = WCS {readOnly}
+ version: string
«Data Type»
Extension
+ any: anyType [0..] +extension
0..1
Figure 7 — WCS DescribeCoverage operation request UML class diagram
Table 11 — WCS DescribeCoverage components
Name Definition
Data type Multiplicity
service Service identifier
String, fixed to “WCS”
one mandatory
Copyright © 2012 Open Geospatial Consortium. 19
version WCS service version
indicator String,
fixed to a pattern of three dot-separated decimal digits
one mandatory
extension Any ancillary information
to be sent from client to server
Extension zero or one
optional coverageId Coverage identifiers
NCName one or more
mandatory
Requirement 21 reqcoredescribeCoverage-response-list-size: The response to a successful DescribeCoverage request with n coverage identifiers shall
contain a CoverageDescriptions element consisting of n CoverageDescription items as specified in Figure 8 and Table 12.
NOTE For brevity, the substructures of
domainSet
and
rangeType
have been omitted in Figure 8. OGC document [OGC 09-146r1] contains their complete definitions.
Figure 8 — WCS CoverageDescriptions UML class diagram
Table 12 lists the components of a CoverageDescriptions list, Table 13 those of a sin- gle CoverageDescription.
20 Copyright © 2012 Open Geospatial Consortium.
Table 12 — WCS CoverageDescriptions components
Name Definition
Data type Multiplicity
coverage- Description
description of a coverage Coverage-
Description zero or more
mandatory
NOTE While an empty list of coverage descriptions cannot occur in the context of the De- scribeCoverage request due to Requirement 18, this data structure is also used in different
contexts by other specifications of the WCS family where zero elements can be a valid result – hence, it is defined as being able to be empty.
Table 13 — WCS CoverageDescription components
Name Definition
Data type Multiplicity
coverageId Identifier of the coverage
described NCName
one mandatory
coverage- Function
GML 3.2.1 coverage func- tion to describe how range
values at coverage locations can be obtained
GML:: CoverageFunction
zero or one optional
domainSet Domain description of this
coverage GML::DomainSet
one mandatory
rangeType Range structure description
of this coverage SWE Common::
DataRecord one
mandatory service-
Parameters Service-specific parameters
of this coverage ServiceParameters
one mandatory
extension Application specific meta-
data Extension
zero or more optional
Requirement 22 reqcoredescribeCoverage-response-contents: The response to a successful DescribeCoverage request containing n identifiers id
1
, …, id
n
shall contain, for each identifier id
i
passed 1≤i≤n, a wcs:coverageDescription consisting of the metadata of the coverage identified by id
i
, that is: the complete wcs:CoverageOffering minus the coverage rangeSet.
Dependency:
http:www.opengis.netspecGMLCOV1.0confgml-coverage
NOTE 1 GML [OGC 07-036] allows, among others, the domain set of a coverage to be referenced exter-
nally, using
xlink:href
. This feature may be useful when the coverage domain set becomes unwieldy in size, which can occur particularly with multi-pointcurvesurface solid-coverages.
NOTE 2 While Requirement 19 does not exclude duplicate coverage identifiers the resulting description
list in such a situation might not always look as naively expected. For example, a request with identifiers 1,1,2 can yield a coverage description sequence 1,2,2 which is valid.
Requirement 23 reqcoredescribeCoverage-response-srsName: If a geometric or temporal object in the domainSet of a coverageDescription specif-
Copyright © 2012 Open Geospatial Consortium. 21
ies an srsName attribute, the value of this attribute shall be identical to the srsName attribute of the boundedBy element of the containing coverageDescription.
Table 14 — WCS ServiceParameters components
Name Definition
Data type Multiplicity
coverage- Subtype
Type name of the coverage on hand
QName one
mandatory coverage-
Subtype- Parent
Recursive list of the cover- age’s supertypes
CoverageSubtype- Parent
zero or one optional
native- Format
MIME type identifier of the cov
erage’s Native Format anyURI
one mandatory
extension Any ancillary information to
be sent from client to server Extension
zero or one optional
Example The response to a valid DescribeCoverage request for coverage with id C0001
might be: ?xml version=1.0 encoding=UTF-8?
wcs:CoverageDescriptions xmlns:xsi
= http:www.w3.org2001XMLSchema-instance
xmlns =
http:www.opengis.netgml3.2 xmlns:gml
= http:www.opengis.netgml3.2
xmlns:gmlcov =
http:www.opengis.netgmlcov1.0 xmlns:swe
= http:www.opengis.netswe2.0
xsi:schemaLocation =
http:schemas.opengis.netswe2.0 http:schemas.opengis.netsweCommon2.0swe.xsd
http:www.opengis.netwcs2.0 http:www.opengis.netwcs2.0wcsAll.xsd xmlns:wcs
= http:www.opengis.netwcs2.0
wcs:CoverageDescription gml:id=
CD0001 gml:boundedBy
gml:Envelope srsName=
http:www.opengis.netdefcrsEPSG04326 axisLabels=
Lat Long uomLabels=
deg deg srsDimension=
2 gml:lowerCorner1 1gml:lowerCorner
gml:upperCorner5 3gml:upperCorner gml:Envelope
gml:boundedBy
wcs:CoverageId C0001
wcs:CoverageId domainSet
Grid gml:id=
gr0001_C0001 dimension
= 2
limits GridEnvelope
-- This is a 5-by-3 matrix -- low
1 1 low
high 5 3
high GridEnvelope
limits axisLabels
Lat Long axisLabels
Grid domainSet
gmlcov:rangeType swe:DataRecord
swe:field name=
singleBand swe:Quantity
definition= http:opengis.netdefpropertyOGC0Radiance
swe:description Panchromatic Channel
swe:description
22 Copyright © 2012 Open Geospatial Consortium.
swe:uom code=
Wcm2 swe:constraint
swe:AllowedValues swe:interval
0 255 swe:interval
swe:significantFigures 3
swe:significantFigures swe:AllowedValues
swe:constraint swe:Quantity
swe:field swe:DataRecord
gmlcov:rangeType wcs:ServiceParameters
wcs:CoverageSubtype GridCoverage
wcs:CoverageSubtype wcs:nativeFormat
imagetiff wcs: nativeFormat
wcs:ServiceParameters wcs:CoverageDescription
wcs:CoverageDescriptions
8.3.3 DescribeCoverage exceptions
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