Reference group usage Introduction

Copyright © 2011 Open Geospatial Consortium 89 • in various forms of data representations – data can be published as raw binary data, OM encoded observations, NetCDF files, image files, video streams etc. • in various processing stages – data can be published as received by the sensor, after level-1 quality checks were performed, level-2 quality checks etc. • in various storage stages – in some domains data is made accessible in some kind of immediately accessible cache but soon after a taskmission was completed the data is moved from there to a long-term data archive • via different protocols – access to data may be performed via FTP, HTTP etc. As an example, an SPS server may use some transient storage to make intermediate results available to the client in various representations using diverse access protocols. Once the next processing step is reached, this data becomes obsolete and some references in the reference groups might be removed, updated, or simply superseded by new reference groups that now point to the next level data. The SPS server would continuously update the reference groups, and clients can differentiate them from those they already know via the identifier assigned to each group by the service. Requirement http:www.opengis.netspecSPS2.0reqDescribeResultAccessreferenceGroupAggregation REQ 69. Any SPS shall aggregate references in reference groups according to Table 41. How references are used in reference groups is defined in the following clause.

7.3.8.1.2 Reference usage

SPS does not provide a direct data access operation. Instead, it provides references to the data or services hosting the data. The various options in describing the data access are outlined in Table 41. Further on, it describes the concrete semantics and usage of the ReferenceGroup properties in detail. 90 Copyright © 2011 Open Geospatial Consortium Table 41 – Service Reference Mapping Option SPS provides Used elements of DescribeResultAccessResponse Cardinality 1 a URL that contains the full request string to be sent against the data service information encoded as OWS Common Reference reference URI: Full request as sent to data service using HTTP GET 1 role URI: describes the role of this reference, in other words what the SPS provides with this reference value shall be identifier for this reference option: http:www.opengis.netspecSPS2.0referenceTyp eFullURLAccess 1 title String: Human readable title for this reference 0..1 identifier URI: unique identifier for the reference 1 abstract String with optional language code: Brief narrative description of this reference for example what it references, normally available for display to a human 0.. format mime type: defines the response format as provided by data service Table 42 provides guidance 1 metadata AbstractMetadata, at least one SPSMetadata shall be included: provides specific metadata for service references given in a DescribeResultAccessResponse – in case of SPSMetadata it identifies the specification that defines the type of servicemethod used for accessing data see Table 50. 1..