Changes between Initial Version and Version 1 of OwsNotes/DataServicesProposal

26/04/07 09:50:20 (14 years ago)



  • OwsNotes/DataServicesProposal

    v1 v1  
     1OwsNotes / !DataServicesProposal 
     3= Service Proposals = 
     5== Implementing a CSML-API service == 
     7A minimal CSML API must be able to do the following with a CSMLDataset 
     8 1. Serve the CSMLFeatureCollection element. 
     9 1. Expose the CSML affordances associated one of its CSMLFeatures. 
     10 1. Serve the output of CSML affordances as a CSMLDataset + associated 
     11    data files.  This will be called a CSMLBundle. 
     13Optionally it would also be useful to: 
     14 1. Serve parts of the CSMLFeatureCollection for efficient querying of  
     15    properties such as grid axes and units. 
     17OwsNotes/OgcServicesReview discusses how the different OGC services could be used to 
     18expose CSML affordances.  Based on that page and the premises above we could 
     19implement a CSML-API service as a combination of WFS and WPS services: 
     21=== A Basic WFS service === 
     23This would serve CSMLFeatureCollections.  Querying parts of the 
     24CSMLFeatureCollection structure would be suppored using XLINK property 
     25queries.  A nice additional feature would be to allow delivery of 
     26features as JSON for easier AJAX client integration. 
     28=== A WPS-affordance service (WPSa) === 
     30CSML affordances would be implemented as WPS processes.  Each process 
     31would produce a CSMLBundle output.  We would need to decide whether 
     32affordance operations block until complete or whether the WPS store 
     33function must be implemented.  WPS-store adds more flexibility and 
     34better response but requires cache control. 
     36== Implementing visualisation services == 
     38We want to: 
     39 1. Plot geospatial data as lat/lon horizontal slices. 
     40 1. Overlay one feature upon another. 
     41 1. Produce both "quick-look" and "publication-quality" images. 
     43Work on the IPCC DDC provides a good prototype for what is possible. 
     44We could again implement a pair of OGC services. 
     46=== A WMS service === 
     48The IPCC DDC already serves CSML GridSeries features through a WMS. 
     49More work is required to make this code more generic (in particular 
     50mapping the WMS and CSML data models).  Other features that can 
     51usefully be viewed as a projection in lat/lon could be renderred to 
     52images and served via WMS, for instance trajectories.  Tools such as 
     53OpenLayers can then be easily configured to overlay WMS sources. 
     55=== A WPS-vis service (WPSv) === 
     57Publication quality plots and plots that aren't lat/lon projections 
     58(e.g. timeseries) would be serves as a WPS.  The IPCC DDC currently 
     59implements this as a custom request on the WMS server.  A WPS could 
     60support queueing of requests that might take a long time 
     61(e.g. animations) using WPS-store.  Overlays could also supported with 
     62more coding time (but also see OwsNotes/CrossSiteIssues).