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69 include many of these and they could be added rather easy. However, more thought
should be given to exactly what should be included in the context of remodeling over the web.
15.2.2 Filter Capabilities
During the OWS-3 testbed, we attempted to execute the Data Aggregation Service against a particular dataset and it eventually failed. This appeared to be due to the fact
that we were accessing a WFS that served a set of world wide features e.g. all the roads in the world. This quickly and clearly identified the fact that the DAS should be
enhanced to include a mechanism of defining an area of interest or spatial filter to limit the returned feature to only the instances within the interest area. In addition, the
possibility exist for additional filters outside of spatial filters could also be implemented.
15.3 Implementation Comments
15.3.1 Intergraph Corporation
Since the DAS endpoint is published to look like a WFS, we use the existing WFS access capabilities within the GeoMedia client to bind and retrieve the mapped data See the
section detailing the WFS interfaces.
In addition, the client provides an interface that allows the user to populate fields with the endpoints of the Mapping Definition File and the WFS URLs to be mapped and
aggregated. Then the user selects a button that makes a SetMappingFile request to the DAS and configures the DAS with the supplied information.
15.4 Recommendations
15.4.1 Mapping Definition Enhancements
Additional work needs to be done to enhance the capabilities defined in the Mapping Definition File. It is understood that it is possible to define the capabilities to map
schemas so they are so complex that it make them difficult to use. However, during the OWS3 testbed there were some use cases identified that the current mapping definition
and DAS service were unable to handle due to current limitations. Some of these included the following:
1. Ability to map enumerated values such as codelists. 2. Apply functions to the remapping to perform such operations as converting from
feet to meters. This process should take the time to plan what operations make sense for the DAS to
perform and then attempt to model a schema for the mapping definition and publish a specification defining the mapping definition separate from the service.
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15.4.2 Data Aggregation Service Configuration
Currently, the Data Aggregation Service can be configured by the user through an extended and hidden request known as “SetMappingFile”. This request tells the Data
Aggregation Service that until otherwise requested, use the information in this SetMappingFile request. The request contains the name of the mapping definition file
and the WFS endpoints to be used by the service.
Although this solution worked for the testbed, it does not seem consistent. If the DAS is truly an extension of a WFS, then the current WFS specification requests should be
extended to include the SetMappingFile request or extend current requests GetCapabilities, DescribeFeatureType, GetFeature to allow optional parameters to
inform a DAS of the endpoints to use. However, if this should be its own service then a separate specification should be written and defined.
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16 GeoVideo Service GVS
A GeoVideo Service provides an integrated client access to live or archived video data and associated technical and geospatial metadata. This section documents the process of
accessing a geovideo services from an Integrated Client.
16.1 Connecting to a GeoVideo Service
