[mapserver-users] ScaleHint

[Rob Atkinson]

Yep - ignoring this functionality will definitely make the software less than
safe to deploy.

Well behaved clients will respect the scale-hint. The mapserver should, IMHO,
generate an error if the scale hint is exceeded - its not quite as strong as
that but it really ought to be mandatory behaviour.

Rob Atkinson

Doug Nebert wrote:

> Paul Ramsey wrote:
> >
> > I have started exploring the WMS capability somewhat... I was wondering
> > why the WMS does not provide a ScaleHint for layers which have
> > explicitly defined min and max scales? What will the MapServer WMS do if
> > a client does  GetMap on a layer using an extent which violates the
> > maxscale? I am thinking in terms of writing a client which knows nothing
> > about the WMS except there is a service there: in order to properly
> > request scale-restricted layers, the ScaleHint is vital. Otherwise the
> > client could request every contour in the province, when in fact
> > contours should only be requested at a close-in zoom level.
> > Thanks for the info,
> > Paul
> >
>
> Gee. I could use this functionality, too. The server already has the
> capability of recognizing MAXSCALE and MINSCALE in the .map files.
> It seems these could easily be coordinated, such that these
> properties could be exported to the capabilities statement and thus
> would be respected if provided in the .map file. So I think this
> is an easy thing to do if you don't treat scalehint as pure metadata
> but is derived from MINSCALE MAXSCALE.
>
> Doug.
>
> > PS - Doesn't requiring the 'map' parameter violate the WMS spec? (I
> > recognize the difficulty, however -- what is a service description
> > absent a map file? Perhaps a simple wrapper example could be bundled.)
>
> --
> Douglas D. Nebert
> Geospatial Data Clearinghouse Coordinator
> FGDC/GSDI Secretariat   Phone: +1 703 648 4151  Fax: +1 703 648-5755
> Pager Messaging:        http://clearinghouse3.fgdc.gov/dougmsg.html
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