[Cartoweb-users] Feedback: cartoweb and thematic cartography (elections)

[Emmanuel BELO]

This Sunday (20060312) will take place communal elections in the Canton 
de Vaud (Switzerland). We have adapted cartoweb 3.2 to show online the 
results:

http://cartoweb.elections-communales.ch/index.php

It is traditional thematic cartography with following problematic:

a) feeding results to be mapped as they are officially published,
b) automatic adaptation of the class intervals on the basis of the results,
c) generation of multiple similar layers,
d) high traffic during the day of the elections,
e) short time to build the application

a) Results are imported in Open Office Calc and the sheets macro 
generates the insert commands for the database, copy-past is possible. 
The risk of typo is reduced. After database import, generation of the 
publications tables and a new mapfile.

b) The mapfile is an .map.php compiled with makemaps.php. It is possible 
to script the mapfile in php. Requests are made to the database to get 
the extent of results for a layer and to compute for each layer the 
class intervals.

c) The capabilities of cartowebs autolayers allow to generate multiple 
layers with similar thematic (for example: political party). For 12 
parties this is a great saving time functionality.

d) High traffic problematic should be solved by reducing the 
functionalities of cartoweb: there is no pan nor zoom so that images can 
be cached by cartoweb. In second place, we use 2 computers, one for the 
database and one for cartoweb. As many concurrent requests arrive, the 
load of cartoweb server increases and it could be impossible to work 
with ease in the database. As feeding the results during the operation 
is important... this was a mandatory. The structure of the relational 
database implies to use views to access data. To win some computing 
time, the views are materialized (snapshots) so that cartoweb does only 
basic select operations.

e) Wishes were prioritized and an importance/time consume balance was 
taking in regard so that this project would feed in the 2.5 weeks that i 
had before me...

Why cartoweb?
We have chosen cartoweb, because of the accessibility of this solution: 
there is no need for a plugin on the client side and it is compatible 
with many types of browsers. As it is an open source software, it is 
possible to adjust the functionalities to our needs and there is no 
license costs.

We are now waiting for the D-Day to come and I'll give you a small 
feedback after the elections.

Hoping everything goes well,

best regards,

Emmanuel BELO
-------------- next part --------------
A non-text attachment was scrubbed...
Name: emmanuel.belo.vcf
Type: text/x-vcard
Size: 337 bytes
Desc: not available
Url : http://lists.maptools.org/pipermail/cartoweb-users/attachments/20060309/b037d609/emmanuel.belo.vcf