Steve,
we use this feature in Fusion via mapscript to save the result of a
spatial or attribute query and then via the CGI (via OpenLayers by
merging new params queryfile=) to draw the query when rendering the
map. It is a *very* convenient and seemingly lightweight (at least in
coding terms) mechanism to draw query results. We don't need to
modify the map file as a result of a query and we don't need to use
mapscript to draw the map (since everything else is on the client for
requesting the map).
We could change this to use another mechanism - when a fusion app
starts, the requested mapfile is copied to a session so we can modify
if necessary (add/remove layers, reorder etc). This means that as a
result of a query, we could add layers that point to temporary shape
files that contain copies of selected features. While this might give
us a bit more control over presentation of the query results, it might
also be problematic for selecting features like points with specific
symbols coming from different layers etc ... I guess we would copy
every layer that had a query result to new layer and modify the styles
but that could get very complex to manage.
One of the requested features for Fusion (MapServer) is to modify the
selection (add features, remove features). We can do this in
MapGuide. Managing things in shapefiles would at least give us an
option to implement this kind of thing, but it would be quite heavy
handed I think.
Overall I would argue to keep it unless you know of a reasonably
simple way to replicate this functionality with mapscript and not
requiring mapscript to draw the map every time (which was what we did
in Chameleon!).
Cheers
Paul
On 13-Mar-09, at 1:04 AM, Steve Lime wrote:
Hi all: Consider this a survey of sorts. I'm wondering how many of
you make use of saving queries, either via the CGI or MapScript.
It's an old feature that isn't terribly useful and I'm trying to
understand the pain the community might incur if they go away in
6.0. If you didn't know they existed or how you might use them then
it's safe to say you don't need 'em.
Steve
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Paul Spencer
Chief Technology Officer
DM Solutions Group Inc
http://research.dmsolutions.ca/
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