OGC and google style tiling

Steven M. Ottens steven.ottens at geodan.nl
Wed Apr 12 04:07:21 EDT 2006

Hi all,

For those who don't know: I'm one of the lead developers on the EduGIS
project, a site which aims to introduce highschool students to GIS. The
site contains a webmapping part, which combined with so called
'lesson-modules' can be used inside the classroom.
We aim to be able to have at least 200 students access the site at one
time. Since it's being used inside the classroom it means that a lot of
students will do more or less the same thing at the same time (following
the tasks in the lesson-modules). This causes quite some stress on the
server. Since it's a free site we have limited budget and cannot put a
google-style server park behind it ;(

Right now we've got apache to serverside cache the umn mapserver output.
This obviously works only for those images that are requested twice
(like the first mapimage). Right now about 30 students can work at the
same time without it becoming unworkable slow. Since serverside caching
works, the next logical step to boost performance would be using tiles
like google.
>From what I know, tiling breaks OGC compatibility, right?
We're using Mapbuilder as client and we prefer to keep using it, since
it's turning into a rather featureful client on the EduGIS site. But the
question arises how to implement tiling inside WMC/OWS-context without
breaking OGC too much.
Also I'm interested in the used algorithms to get tiling working.


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