Major updates to OWS and the Pyramid model

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Folks, I have checked into GitHub a lot of stuff that needed updating for quite some time.  The ga_ows application now “officially” supports WMS – as in there’s documentation on how to use it now.  WMS has been modified significantly to be in line with the way WFS works.  There are numerous speed and efficiency improvements in GeoDjango’s WMS implementation.  Other big news is that there is now Celery support for WMS’s rendering step, meaning that you can do a number of cool things, including:

  • Render WMS tiles on a cluster
  • Pre-cache WMS requests that are common
  • Use the WMS renderer to populate a Pyramid instance (requires manual coding) instead of using gdal_retile.
The (reasonably) complete list of changes:
ga_ows:
  • Simplify the creation of WMS instances and put them more in line with other Django Generic Views (tutorials on this will come in due time)
  • Added documentation: ga_ows.rendering.styler, ga_ows.rendering.palettes, ga_ows.rendering.geodjango_cairo_renderer, ga_ows.views.wms. ga_ows.utils
  • Removed ga_ows.views.wmsconfig
  • Added support for caching via a WMSCache class
  • Added support for caching by default into the GeoDjangoWMSAdapter class
  • Added support for a new keyword parameter to WMS, “fresh”, which is a boolean parameter when set to true will force the rendering of a new image and refresh the cache at the same time.
  • Added “name” and “required_fields” keyword argument to the styler.Stylesheet constructor. “required_fields” gives the query engine hints as to how to make the query more efficient for rendering.
  • Added “simplify” keyword argument to GeoDjangoWMSAdapter.  Simplify is false by default. Given “true” it uses GEOS simplify to reduce geometry complexity for rendering LineString and Polygon objects
  • Added tastyhacks.py to allow GeoDjango models to expose RESTful APIs that return GeoJSON instead of plain JSON.
ga_pyramid
  • Updated to support GetCapabilities
  • Removed “application” and “cls” parameters from the Pyramid’s WMSAdapter class.
New documentation can be found at:
  • http://www2.renci.org/~jeff/docs/ga_dynamic_models
  • http://www2.renci.org/~jeff/docs/ga_ows
  • http://www2.renci.org/~jeff/docs/ga_irods
I will attempt to get some tutorials up for using WMS in the next two weeks.