[OpenLayers-Users] Implementing a layer for a proprietary WMS-like service

[christopher.schmidt at nokia.com]

On Aug 3, 2010, at 9:42 AM, ext Franz Buchinger wrote:

> Hi Bart,
> 
> yes, I've set these options. I noticed that these multiple requests only happen when I set transitionEffect: 'resize'. 

This is basically expected. The transition effect creates multiple tiles, and since
creating images is generally considered to be 'cheap' in OpenLayers -- since 
images should be served from cache -- we just create more tiles, rather than
copying existing ones in any way.

So this is by design; if you don't like the design, you'll need to do some 
more coding to fix it :)

-- Chris

> I'm using OpenLayers 2.9.1.
> 
> Franz
> 
> 
> 
> 2010/8/3 Bart van den Eijnden (OSGIS) <bartvde at osgis.nl>
> Hi Franz,
> 
> and have you verified you only have a single tile?
> 
> Do you have singleTile: true, ratio: 1 and buffer: 0 in your layer options?
> 
> Best regards,
> Bart
> 
> >  Hi Bart,
> >
> > I'm almost done with my layer implementation. The only problem: my
> > getURLasync() Method gets triggered far too often (about 3x per pan/zoom
> > action).
> >
> > How can I make sure that getURLasync is only triggered once per map
> > action?
> >
> > Franz
> >
> > 2010/8/3 Bart van den Eijnden (OSGIS) <bartvde at osgis.nl>
> >
> >> Hi Franz,
> >>
> >> check out OpenLayers.Tile.Image.
> >>
> >> Best regards,
> >> Bart
> >>
> >> > Hi Bart,
> >> >
> >> > thanks for the fast and helpful response!
> >> >
> >> > One question though: which class actually invokes the methods
> >> > OpenLayers.Layer.ArcIMS.getUrl and OpenLayers.Layer.getUrlAsync?
> >> >
> >> > They seem to be overriden methods, but i couldn't find them in
> >> > OpenLayers.Layer.Grid or OpenLayers.Layer.HTTPRequest.
> >> >
> >> > kind regards,
> >> >
> >> > Franz
> >> >
> >> > 2010/8/3 Bart van den Eijnden (OSGIS) <bartvde at osgis.nl>
> >> >
> >> >> Hi,
> >> >>
> >> >> I would advise you to look at OpenLayers.Layer.ArcIMS which uses a
> >> >> similar
> >> >> approach.
> >> >>
> >> >> Best regards,
> >> >> Bart
> >> >>
> >> >> > Hi,
> >> >> >
> >> >> > I'm a frontend developer and was programming a web viewer for a
> >> >> > proprietary,
> >> >> > WMS-like map service.
> >> >> > I discovered Openlayers one month ago and I'm really fascinated by
> >> its
> >> >> > awesome capabilities, so I decided to integrate our map service in
> >> >> > OpenLayers.
> >> >> >
> >> >> > Here is a short description how the map service works:
> >> >> >
> >> >> > The client sends an AJAX request containing the current map bounds,
> >> >> the
> >> >> > map
> >> >> > id and the pixel size of the map.
> >> >> >
> >> >>
> >> map=22&px=1720&py=833&left=2504400&right=2544000&top=5699500&bottom=5669500&type=0
> >> >> >
> >> >> > The server responds with the generated map image (url) and the
> >> >> corrected
> >> >> > bounds:
> >> >> > <MapProperties>
> >> >> >   <mapLeft>2493227.6110444176</mapLeft>
> >> >> >   <mapTop>5699500</mapTop>
> >> >> >   <mapRight>2555172.3889555824</mapRight>
> >> >> >   <mapBottom>5669500</mapBottom>
> >> >> >   <mapType>0</mapType>
> >> >> >   <overviewMap>22</overviewMap>
> >> >> >   <url>
> >> >> http://localhost/cgmCache/41600065-c3d2-4934-9feb-78a32f6668c8.png
> >> >> > </url>
> >> >> > </MapProperties>
> >> >> >
> >> >> > The maps are always single-tiled.
> >> >> >
> >> >> > My first approach was to write a ProprietaryMapLayer, that executes
> >> >> the
> >> >> > map
> >> >> > request and creates an ImageLayer with the result url and its
> >> bounds.
> >> >> > When the ImageLayer is moved, a new request is performed, the
> >> current
> >> >> > ImageLayer is destroyed and a new one generated. The disadvantage:
> >> >> there
> >> >> > are
> >> >> > now 2 layers representing one map, which leads to confusion in the
> >> >> layer
> >> >> > switcher control.
> >> >> >
> >> >> > I read over the code of Layer.WMS, which inherits from Layer.Grid
> >> and
> >> >> also
> >> >> > makes use of Tile.Image, but it's difficult to derive a solution
> >> from
> >> >> it,
> >> >> > since all the request/response handling is already integrated into
> >> the
> >> >> > layer. Furthermore, WMS simply responds with tile images, whereas I
> >> >> have
> >> >> > to
> >> >> > deal with an xml response.
> >> >> >
> >> >> > Any ideas how I could implement my layer?
> >> >> >
> >> >> > kind regards,
> >> >> >
> >> >> > Franz
> >> >> > _______________________________________________
> >> >> > Users mailing list
> >> >> > Users at openlayers.org
> >> >> > http://openlayers.org/mailman/listinfo/users
> >> >> >
> >> >>
> >> >>
> >> >> --
> >> >> Looking for flexible support on OpenLayers or GeoExt? Please check
> >> out
> >> >> http://www.osgis.nl/support.html
> >> >>
> >> >> Bart van den Eijnden
> >> >> OSGIS
> >> >> bartvde at osgis.nl
> >> >>
> >> >>
> >> >
> >>
> >>
> >> --
> >> Looking for flexible support on OpenLayers or GeoExt? Please check out
> >> http://www.osgis.nl/support.html
> >>
> >> Bart van den Eijnden
> >> OSGIS
> >> bartvde at osgis.nl
> >>
> >>
> >
> 
> 
> --
> Looking for flexible support on OpenLayers or GeoExt? Please check out
> http://www.osgis.nl/support.html
> 
> Bart van den Eijnden
> OSGIS
> bartvde at osgis.nl
> 
> 
> <ATT00001..txt>