[mapserver-users] A Question of Group

Lime, Steve D (DNR) Steve.Lime at state.mn.us
Wed Mar 3 12:26:01 PST 2010


Version 5.6 introduces an XML mapfile schema and stylesheet. So (in theory) one could manage a mapfile in XML and transform it for use. We intend to allow more direct use somehow although that hasn't been decided. At the code sprint an on-the-fly transformation was tested successfully. Other options include just-in-time conversion from XML to .map (via XSLT) or native XML parsing. We'll see...

On a side note, developers here played with using HTML legends to create output suitable for use with the YUI collapsible menu widgets. In the end we gave up and instead worked up a PHP/MapScript-based solution. The script works off a mapfile and a bit of embedded metadata to produce a JSON legend object. That object is passed in turn to a legend widget that is based on YUI. The legend is somewhat framework agnostic and we've hooked it up to dbox (where it started) and more recently OpenLayers. With an XML mapfile one could probably to the JSON production independent of MapScript or entirely on the client although that's probably sharing too much information.

Steve
________________________________________
From: mapserver-users-bounces at lists.osgeo.org [mapserver-users-bounces at lists.osgeo.org] On Behalf Of Bill Thoen [bthoen at gisnet.com]
Sent: Wednesday, March 03, 2010 1:47 PM
To: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] A Question of Group

Bob Basques wrote:
>
> Bill,
>
>
> This is a shameless plug for GeoMoose functionality, it was prompted
> by your comments below however, so I don't feel too bad  :c)
>
>
Grab every opportunity that sets you up for a pitch! Although I'm
actually not unhappy with HTML Legends --I've found workarounds for
things I don't like-- but it would have been nice to have known in
advance where it runs out of steam or just doesn't go, so I'd know
whether I would reach the point of implementing kludges before or after
I reached my goal.

GeoMoose sounds pretty good and seems to solve my problems 1-2-3... But
before I go try it out now instead of later and spend a lot of time I
can't spare contemplating a software switch and testing its capabilities
for possible use in a project with a tight  deadline,  can you highlight
for me the top two or three areas where the hard, cold ground rises up
to meet it (i.e. where it falls on its face)? I'm not looking for what's
broken, but more along the lines of what it is NOT designed for, so I
don't make th e mistake of trying to use in a situation where it will
not do well.

> *  Each layer (or group of layers) is controlled via it's own mapfile,
> while this might seem cumbersome to manage, it does allow for separate
> and integrated management of data layers by many data custodians,
> which is what GeoMoose was originally designed for, many data
> custodians doing their own thing.  It's also very good for automation
> purposes in general.
>
>
One of the both strong points and weak points in the FOSS mapping
software I've seen so far is its almost universal core dependence on
mapfiles or templates as the driving mechanism. These are powerful in
that the are easily modified, human and machine readable and you can
record layer "states" and mix and match the "objects" later on as you
like to create alternate configurations. But where they're a weak point
is when you want to provide a warm 'n fuzzy front end for User B. Goode.
Templates are difficult to work with at that point. They're based on the
1950s-60s notion of batch programming in which the programmer decides
where the process starts and ends. So when you try to build an
interactive, user-driven interface on top of this, the bugs and
shortcomings you tend to run into are usually rooted in a sort of
schizophrenia between the two paradigms. Has anyone here considered
breaking down the rigidity of the mapfile architecture by writing them
in XML or JSON formats so they can be more easily manipulated by an
application?

- Bill Thoen

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