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SOS extension for the GeoServices REST API
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SOS extension for the GeoServices REST API


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  • 1. This talk describes a project which 52°North, ATKINS, and conterra arecurrently conducting for the European Environment Agency.The general aim is to provide the environmental data of the EEA collectedfrom various data sources in a homogeneous way.As a requirement of this project, 52°North has developed an extension forthe GeoServices REST API based on ArcGIS Server 10.1. This extensionresembles the functionality of a Sensor Observation Service and embeds thisSOS functionality into the Geoservices REST API which is currentlyworking it‘s way through OGC. 1
  • 2. EEA‘s mission is to support the sustainable development and improvementof Europe‘s environment, by providing timely, targeted and reliableinformation. 2
  • 3. The EEA is a centralized European agency based in Copenhagen.It is collecting data from several environmental organizations from overall32 member states. 3
  • 4. Besides their responsibility to collect the data from the member stateorganizations, the EEA disseminates the data and derived informationproducts. The data then serves as a basis to support European decisionmakers, but also to inform the general public.In her keynote talk at the ESRI user conference 2011, EEA‘s executivedirector, Jacqueline McGlade, pointed out in-situ sensors as an increasinglyimportant data source for the EEA. 4
  • 5. Thereby, the relevant sensors are manifold contributing to different datathemes. 5
  • 6. However, this variety of data sources at the associated member stateorganizations leads to a significant problem for the EEA.This figure illustrates the current situation.The data providers offer their data in proprietary formats via FTP or HTTPaccess.To cope with this variety, the EEA has to write manually adapters for eachnew data source. To do this in a timely manner is difficult.Then, the data is imported into the existing infrastructure which is based onESRI‘s ArcGIS technology at the EEA. The data is provided to dataconsumers via application-specific interfaces. 6
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  • 8. So, instead of various data access interfaces, the EEA will promote the SOSinterface in future towards their data providing member state agencies. 8
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  • 10. This slide shows the architectural overview of the developed solution. 10
  • 11. Before the SOS Geoservices REST API is presented, here a short review ofthe general Geoservices REST API which is currently in the OGCstandardization process within the Geoservices REST SWG.This screenshot shows an excerpt of that Geoservices REST API, thedefinition of the Layer / Table resource. As you can see at the bottom, eachresource description contains the resource hierarchy figure. 11
  • 12. The SOS Geoservices REST API is aligned with the general GeoservicesREST API.We defined three types of resources offered by an SOS server:Observations, Procedures (=sensors) and Features (or features of interest).From this selection of resources, you can already see that the underlyingmodel of the SOS REST API resembles the O&M 2.0 model.In fact, you can say, that this SOS REST API implements the conceptualmodel of the SOS 2.0. 12
  • 13. The ArcGIS Server SOS Extension has been tested for a data set from theEEA which has been generated by a network of around 1500 air qualitystations all across Europe, as shown in the figure.In an example setup, 30 days of data were loaded into the database whichmeans over 1 million observations. 13
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  • 15. As an example, the important Observation resource is describe in somemore detail in the following.By accessing the Observations resource, a description of so-calledobservation offerings are returned to the client. They group observations andgive information about those observation groupings, such as temporal andspatial extent.Then, observations can be requested by using the ‚query‘ operation on theObservations resource. Those query operations are the common way offiltering on resources within the Geoservices REST API. 15
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  • 17. This query operation allows to filter on the observations resource withseveral parameters. Those parameters are basically the same as theGetObservation operation of the SOS 2.0 supports. 17
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  • 19. The returned observations are encoded in a JSON format. Here, a simplifiedexample is shown.The newly defined JSON encoding is aligned with O&M 2.0. 19
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