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Copyright © 2016 Open Geospatial Consortium.
7.5 Query
7.5.1 Feature query
In a query response, the CubeWerx server encodes multimedia property values by reference rather than encoding the values in-line in order to keep the bulk of the response
down. Here is an example of a REST URL that returns a wwAccess feature with a photo:
http:www.pvretano.comcubewerxcubeservdefaultwfs2.5.0ows11wwAccessCWFI D.WWACCESS.0.34729.BA89DFD04C0B73161F20020000
. Resolving the href URL that is the value of the Photo property will retrieve the image.
Although not yet implemented in the CubeWerx server, in the future a client would be able to use the resolve parameters see OGC 09-025r2 clause 7.6.4 to control whether
the multimedia data is encoded in-line or not [resolve=none|local means that the value is referenced; resolve=remote|all means that the value is encoded in-line in the response].
NOTE 1: If you follow the above link in your browser, the response may be HTML as the browser sets the Accept header to prefer HTML output. Adding the f parameter allows GML to
be returned: http:www.pvretano.comcubewerxcubeservdefaultwfs2.5.0ows11wwAccessCWFID.WW
ACCESS.0.34729.BA89DFD04C0B73161F20020000?f=applicationgml2Bxml;20version=3 .2
NOTE 2: The editor is still working of the GeoJSON
generation of multimedia values but the pattern will be that established for GML i.e. the value shall be encoded either in line or by
reference depending on the value of the resolve query parameter.
7.5.2 Property Value query
Getting the multimedia value of a property is simply a matter of using a GetPropertyValue
operation or referencing the property values URL. Here is an example of the latter:
http:www.pvretano.comcubewerxcubeservdefaultwfs2.5.0ows11wwAccessCWFI D.WWACCESS.0.34709.BA89DFD04C0B73161F20020000photo?f=applicationgml
2Bxml;+version=3.2 .
This is very nice but it would be better to be able to stream the actual or native binary value without the response container. In this way a client, say a browser, can handle the
multimedia value in whatever manner it has been configured to do so e.g. a browser could display a photo, or play the audio or video clip.
The initial idea for streaming multimedia values from a WFS was to define a new operation, similar to the one found in the
CSW-ebRIM profile of the catalogue , called
GetRepositoryItem . However, a better approach is to use what is already defined in the
WFS; that is, the GetPropertyValue
operation.
Copyright © 2016 Open Geospatial Consortium.
23 The
GetPropertyValue operation or accessing a property values URL does exactly as
its name implies -- it fetches the value of a property of a feature. Unfortunately it returns the value encoded in-line as a base 64 value or referenced by URL within a
ValueCollection container. There needs to be a way to signal to the server that a
multimedia property value should be streamed in its native encoding and not as part of a standard response container. To satisfy this requirement a special token named native
was defined and implemented in the CubeWerx server. This token can be used in the Accept header or as the value of the outputFormat|f parameter to let the server know that
a multimedia value should be streamed in its native binary encoding tagged with its native MIME type. Here is an example:
http:www.pvretano.comcubewerxcubeservdefaultwfs2.5.0ows11wwAccessCWFI D.WWACCESS.0.34709.BA89DFD04C0B73161F20020000photo?f=native
8 Enterprise-to-enterprise WFS-T synchronization
8.1 Introduction
The original intent in the testbed was to deploy a Geosynchronization service see OGC 10-069r3 to support enterprise-to-enterprise synchronization. However, because of the
synchronization requirement appearing at multiple levels, starting from mobile devices out in the field and scaling up to enterprise level synchronization between WFS servers, it
was decided in the OGC Testbed-11 to develop a peer-to-peer synchronization protocol to satisfy the requirement.
This clause describes the peer-to-peer sync protocol implemented in the testbed to satisfy the enterprise-to-enterprise sync use case from OGC Testbed 11.
8.2 Components
Figure 2 illustrates the components involved in the OGC Testbed-11 enterprise-to- enterprise sync experiment.
Figure 2 - Components of the Sync experiment
The experiment was performed between two WFSs; the CloudantIBM WFS and the CubeWerx WFS. Table 3 lists the product versions and endpoint of the servers.