[mapserver-users] mapserver architecture for multi-websites on several machines

[Claude Philipona]

Thanks for your help. A few more questions:

- is OGC WMS also supported in PHP/Mapscript (source comming from the nightly 
build) or only in the cgi version?
- if yes, where how can we use the different getCapabilities, getMap, 
getFeature wiht PHP/Mapscript.
- where can i find a little more documentation or examples on how to use OGC 
WMS with Mapserver and PHP/Mapscript?


> I agree with John's opinion that using the OGC WMS (Web Map Server)
> support in MapServer should allow you to do everything you need, and
> since it builds on a commonly adopted standard it will allow you to
> eventually expand your pool of servers to servers from other vendors
> if
> needed.
> 
> As John wrote, the WMS spec includes 3 types of request: 
> 
> - getCapabilities returns an XML document with list of layers and
>   features supported by the server.
> - getMap returns an image of the map with specified layers and BBOX
> - getFeatureInfo is used for querying the map obtained from a previous
>   getMap request.
> 
> One more thing you'll need is a server application that can integrate
> layers from several remote servers and return a single map image to
> the
> client browser... this is referred to by the OGC WMT (Web Mapping
> Testbed) group as a "cascading server" (well, technically a cascading
> WMS serves maps to other WMS servers and not directly to browsers...
> so
> maybe we should just say WMS client and not cascading server).
> 
> Anyway, this is not available in MapServer yet but we will be adding
> this to Mapserver in the next few months.
> 
> Note that some people have implemented JavaScript WMS clients that
> combine the WMS maps directly in the web browser, and that might do
> the
> trick for you... perhaps those who have developed this kind of WMS
> clients can comment more.
> 
> I hope that helps,
> 
> Daniel
> 
> "Hockaday, John" wrote:
> > 
> > Hi Claudia,
> > 
> > I was hoping that someone with more experience with this type of
> subject
> > would answer your question but it seems that they haven't so I will
> give you
> > the little knowledge that I have on the subject.  Hopefully, lots of
> people
> > will get annoyed with the errors in this e-mail that I am proposing
> and they
> > will correct me for your benefit.  I for one am very interested in
> the
> > outcomes of your project as I will have to look into something similar
> soon.
> > 
> > The Open GIS came up with a standard for accessing data across the
> web.  (I
> > think that the OpenIGS is called something different now but I'm not
> sure.)
> > One of the commands is something like getimage().  I believe that
> mapserver
> > version 3.5 has the ability to handle Open GIS capabilities.  I seem
> to
> > remember earlier versions having the getimage() command but I'm not
> sure
> > about that either.
> > 
> > You could use the getimage() command to each of your mapservers and
> they
> > should return an image.  You could then build these images on top of
> each
> > other, if they are transparent, to make a final map.  GD can do this
> if
> > mapserver doesn't already have a command to do it.  You may have to
> make
> > more that one call to each map server as the order of the layers may
> be
> > important to your final map.
> > 
> > I think that there is a similar OpenGIS command to get information
> about a
> > layer from a remote map server.  It may be something like getinfo(). 
> This
> > is probably a more simpler command as it may only need information
> from one
> > mapserver.
> > 
> > I would *strongly* recommend that you use the OpenGIS standard as a
> lot of
> > work has gone into this standard and you will greatly benefit from
> their
> > detailed efforts.  I worked on a system of connecting to many map
> producing
> > servers a long time ago and it was full of problems therefore, we
> stopped
> > doing it.  Since then, the OpenGIS has addressed those problems in
> their
> > work.
> > 
> > Good luck and please keep this list aware of what you are doing.  I
> want to
> > build on your work if you don't mind me "borrowing" your
> intellectual
> > property and code.   ;--)
> > 
> > John
> > 
> > > -----Original Message-----
> > > From: Claude Philipona [SMTP:claude.philipona at camptocamp.com]
> > > Sent: Friday, July 13, 2001 8:38 PM
> > > To:   mapserver-users at lists.gis.umn.edu
> > > Subject:      [mapserver-users] mapserver architecture for
> multi-websites
> > > on several machines
> > >
> > > We are starting a project using Mapserver (PHP/MapScript) for
> building a
> > > cartographic server which could be used by different client
> web-sites on
> > > different machines. The server will propose a large set of raster
> map from
> > > 1:25'000 to 1:1'000'000. The client web-sites will be able to use
> the
> > > central
> > > mapserver to interactivly geocode any kind of information (points,
> lines,
> > > surfaces) using an applet and to visualize and to navigate thru
> the
> > > obtained
> > > geocoded objects.
> > >
> > > Each site using Mapserver is totally independent should be able to
> > > integrate the
> > > map directly (no frames).In this configuration we don't have a web
> borwser
> > > making
> > > direct request to MapServer, but rather the web server machines
> would have
> > > to
> > > make the cartogrphic request to the mapserver machine. This is a
> kind of
> > > wms.
> > >
> > > My question: What is the best solution to implement this kind of
> > > architecture?
> > > Has anybody already done such thing?
> > >
> > > My ideas were to use WDDX (Web Distributed Data Exchange,
> > > http://www.openwddx.org/faq/) to exchange the required parameters
> between
> > > the
> > > mapserver box (coordinates of the click, shapes ON,...) and the
> webserver
> > > boxes
> > > (url of the map image,...). So the Webserver (php enabled) would
> post a
> > > wddx file
> > > (containing the serailzed parameter) to the MapServerPHP-MapScript.
> After
> > > deserialization PHP/Mapscript will process the map request and
> return wddx
> > > file
> > > (containing the url of the images and other important parameter).
> > >
> > > Is it the way to go to get good performance? Is there a better way
> to do
> > > it?
> > >
> > > Other question: I was palnning to start this development using
> directly
> > > Mapserver
> > > 3.5, providing that the system will not enter in production before
> > > november. Is
> > > 3.5 stable enough? Any timesacle for the official release?
> > >
> > > Claude Philipona
> 
> -- 
> ------------------------------------------------------------
>  Daniel Morissette               morissette at dmsolutions.ca
>  DM Solutions Group              http://www.dmsolutions.ca/
> ------------------------------------------------------------
>   Don't put for tomorrow what you can do today, because if 
>       you enjoy it today you can do it again tomorrow.
> 
> 




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Claude Philipona
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