Kai Lautaportti

The fourth (and my first) Snowsprint was held in Bregenzerwald, Austria during 27.03. - 3.2.2007. Altogether 56 developers attended the sprint from 14 different countries who worked on a variety of topics including calendering, multimedia, KSS, GIS, REST, textmate extensions, and caching.

The Gasthaus Hirschen where the sprint was held at proved to be everything one could hope for and the great common room was just the right environment for a week of intensive brain storming and coding.

My goals for the sprint were to learn more about the upcoming Plone 3.0 and to continue on the work on the next major version of PrimaGIS. In earlier sprints in Dublin and Seattle we had already refactored the Cartographic Objects for Zope (ZCO) and PrimaGIS using the Component Architecture of Zope 3 and now it was turn to work on the Plone UI for PrimaGIS.

I had decided to use Zope 3 technologies as much as I could, which meant I would be using Zope schemas and formlib for all forms in PrimaGIS. I also wanted to learn how to implement custom schema fields and widgets using formlib. This all turned out to work quite well, although the Zope2 publisher and security mechanism required to do some acquisition trickery to make everything play nicely together.

One exciting new feature of Plone 3.0 is the KSS (Kinetic Style Sheets) framework (found in the plone.kss and plone.app.kss packages), which makes it extremely simple to do cool AJAX style programming without having to touch Javascript at all. I took part in the KSS tutorial given by Godefroid Chapelle and Balázs Reé which helped to get started working with KSS really fast. This turned out especially useful in implementing the custom formlib widgets.

In addition to the UI work I also worked on an experimental Web Map Service (WMS) server implementation for PrimaGIS. In Zope 3 terms, this simply meant that I needed to implement a view for the primagis.map.Map object that implements the WMS specification. The immediate benefit of implementing WMS server support is that then PrimaGIS maps may be reused by any standards compliant mapping client totally independent of Zope and Plone.

For PrimaGIS itself the WMS support means that, for example, it’s now possible to chain multiple PrimaGIS maps together so that one PrimaGIS instance is able to use the data provided by another. Another cool thing was that we can now provide alternate UIs for the PrimaGIS maps. As an experiment I integrated the Open Layers Javascript UI into PrimaGIS which worked right out of the box. All this code is still very experimental and in the future we will need push most of it into OWSLib and have PrimaGIS use that to implement WMS support.

I will post more detailed entries on how the Plone 3 version of PrimaGIS works and how it differs from the current version. For now you can check out the code at the following branches:

http://svn.gispython.org/svn/zope/ZCO/branches/zco3
http://svn.gispython.org/svn/zope/PrimaGIS/branches/primagis-plone-3.0

or alternatively use the primagis.buildout system to build a development instance (using the --develop switch) which contains the latest code.

Many thanks to Lovely Systems for hosting a great sprint. See you next year!

This entry was posted on Tuesday, February 6th, 2007 at 19:36 and is filed under primagis, plone, zope. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.