A requester MAY
send a GetMetadata request message to an endpoint to
retrieve the metadata associated with that endpoint. This operation MAY be
supported by WS-MetadataExchange compliant service
endpoints. Observe that, in the case where a service endpoint is also a [WS-Transfer] resource, the [WS-Transfer] Get operation allows requesters to
retrieve the resource representation associated with that endpoint (i.e. the
"data"), while the GetMetadata operation
can be used to retrieve that endpoint's metadata. The normative outline for a GetMetadata request is:
[Action]
http://www.w3.org/2010/08/ws-mex/GetMetadata [Body]
<mex:GetMetadata Content='xs:anyURI' ? ...>
<mex:Dialect Type='xs:QName'Identifier='xs:anyURI' ?
Content='xs:anyURI' ? .../> *
xs:any* </mex:GetMetadata>
The following
describes additional, normative constraints on the outline listed above:
[Body]/mex:GetMetadata@Content
This OPTIONAL attribute,
when present, specifies the default content form IRI for
this request. When this attribute is not
present, the default content
form IRI is
"http://www.w3.org/2010/08/ws-mex/Content/Any".
If no dialect elements
are present in this request, the response MUST
include only MetadataSections of the content form
specified by this attribute.
This specification defines
the following content form IRIs:
|
Content Form IRI |
Form |
|
http://www.w3.org/2010/08/ws-mex/Content/EPR |
A MetadataReference
element is returned |
|
http://www.w3.org/2010/08/ws-mex/Content/URI |
A MetadataLocation
element is returned |
|
http://www.w3.org/2010/08/ws-mex/Content/Metadata |
The metadata is embedded |
|
http://www.w3.org/2010/08/ws-mex/Content/Any |
The service is free to choose any content form |
|
http://www.w3.org/2010/08/ws-mex/Content/All |
The service MUST return all available content
forms |
[Body]/mex:GetMetadata/mex:Dialect
When this repeating OPTIONAL element is present, the response MUST
include only MetadataSections corresponding to
metadata specified by the combination of the QName,
Identifier and Content attributes of each of the Dialect elements. For each
Dialect element if there is no metadata for that combination of attributes then
the response MUST NOT include any MetadataSections
for that Dialect element.
When this element is not present, the endpoint MUST return all
available metadata.
[Body]/mex:GetMetadata/mex:Dialect@Type
This REQUIRED attribute specifies the Metadata Dialect. The
response MUST only include MetadataSections
corresponding to the Dialect specified by this QName.
If the receiver does not have any MetadataSections of
this indicated Dialect, the response MUST include zero MetadataSections
for this QName.
[Body]/mex:GetMetadata/mex:Dialect@Identifier
When this OPTIONAL attribute is present, the response MUST include
only MetadataSections with the indicated identifier;
if the receiver does not have any MetadataSections of
the indicated identifier, the response MUST include zero MetadataSections
for this QName/Identifier pair. When this attribute
is not present, the implied value is any identifier. If multiple MetadataSections have the indicated Dialect and Identifier
then all of them MUST be returned.
[Body]/mex:GetMetadata/mex:Dialect@Content
For the dialect indicated, the
response MUST include only MetadataSections of the
content form specified by this attribute.
When this OPTIONAL attribute
is not
present, it defaults to the value of the [Body]/mex:GetMetadata@Content
attribute.
the
response MUST include only MetadataSections of this specified content form. If
the specified content form is not available, or not known, then the response
MUST include zero MetadataSections of the specified form for this
QName/Identifier pair. This specification defines the following content form
IRIs:
|
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When not present the default value is
"http://www.w3.org/2010/08/ws-mex/Content/Any".
If an endpoint
accepts a GetMetadata request, it MUST reply with a GetMetadataResponse message. The normative outline for a GetMetadataResponse is:
[Action]
http://www.w3.org/2010/08/ws-mex/GetMetadataResponse [Body]
<mex:GetMetadataResponse ...> <mex:Metadata ...> ... </mex:Metadata> xs:any* </mex:GetMetadataResponse>
The following
describes additional, normative constraints on the outline listed above:
[Body]/mex:GetMetadataResponse/mex:Metadata
The body of the response message MUST contain one mex:Metadata element as defined in 4 Web Services Metadata Collection.
This operation
is safe; it will not result in any side effect imputable to the requester. This
means that in case of an underlying protocol error that might get unnoticed,
resending the same request can be done automatically.