[OSGeo-Standards] Re: [tiling] OGC Tiled WMS Discussion Paper

Sophia Parafina sophia.parafina at ionicenterprise.com
Fri Sep 7 15:25:59 EDT 2007

I've asked Carl Reed at OGC to make it available for comment.


Christopher Schmidt wrote:
> On Fri, Sep 07, 2007 at 10:47:27AM -0400, Frank Warmerdam wrote:
>> Folks,
>> I was contacted by Edric Keighan about a discussion paper that was
>> recently submitted to OGC (with Cubewerx as the editor) titled:
>>    07-057r2 OpenGIS Tiled WMS Discussion Paper
> I'm guessing this would be a continuation of OGC 07-057? The editors of
> that were not Cubewerx, but from uab.cat, if my records serve. I'd be
> interested in seeing either of the two documents, and would ask that  
>> I believe it is roughly comparible in goals to this work:
>>    http://wiki.osgeo.org/index.php/WMS_Tile_Caching
>> I believe Edric is interested in feedback on the paper and support for the
>> proposal (for those of us who are OGC members) and perhaps more importantly
>> he is interested in implementations of the specification within our projects
>> with OpenLayers being the most obvious candidate.
> OpenLayers is unlikely to add support for further tiled WMS
> specifications through the work of its current set of developers.
> Additional layers would need to be created, tested, and supported by
> some other person who would accept 'ownership' of the layer type: I've
> already avoided including some functionality in OpenLayers simply
> because no one was willing to take on the task of supporting it. 
> If some person or organization is willing to take on the task of
> supporting a layer, then in general, OpenLayers is open to the task of
> adding that functionality. However, I'm somewhat hesitant to include
> yet-another way of accessing pre-cached WMS information: especially if
> it has not taken into account the design goals of the Recommendation we
> created at the last FOSS4G, which is described at:
>   http://wiki.osgeo.org/index.php/WMS_Tiling_Client_Recommendation
> An example of things we explicitly discussed and discarded: 
>  * GetTile requests -- we wanted to stick with GetMap, and simply allow
>    for matching the map request to a tile when appropriate.
>  * Using anything other than the standard GetCapabilities for describing 
>    functionality: GetCapabilities allows for vendor extensions, and this
>    seemed the right way to pass the information back to the client
>  * Starting the tiles at the '0,0' point of the world  (Instead choosing 
>    to go for the lower left corner). Note that this is different from
>    Google's tiles, but the same as WorldWind's. 
>  * Creating any new form of requests -- it's easiest for client
>    functionality to simply extend the existing requests rather than
>    creating new formats. 
> Again, I don't know what's in the document: if someone could tell me
> more specifically how to get a copy of it, I could offer a more formal
> review from the point of view of an implementor of a tile map server.
> Thanks for the heads up, Frank. 
> Regards,

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