[mapguide-internals] Tile maps...

[Paul Spencer]

inline ...

On 14-Sep-07, at 10:48 PM, Jason Birch wrote:

>
> Yes, I was thinking about this, but was also thinking that managing  
> selections on two maps might be a bit annoying to deal with :)  As  
> long as Paul's doing it I guess I don't have much to complain  
> about...  That was a guarantee for the first integration, right  
> Paul? :)

er ... maybe not.

>
> I think that with any serious tiling implementation, a requirement  
> would be to be able to hit multiple hosts for the tiles in round- 
> robin for a single user, even if the hosts are all answered by the  
> same server.  The two-active-connections limit that most users face  
> really slows down tile maps if they're fetching all of the tiles  
> from a single host.  Especially when one of those pipes is being  
> held up by an active JS script.

OpenLayers has the ability to set multiple tile sources per tiled  
layer already, we just need to find a way to expose that in the  
application definition, probably as an Extension to a <Map>.

>
> Personally, I would like to see the tiling stuff re-implemented as  
> a rest-based filter / error handler on top of Apache/IIS/etc.  This  
> would allow the straight files to be served natively/statically  
> with incredible performance if they exist (with no map agent  
> getting in the way), and would allow the map agent to only deal  
> with requests that haven't already generated images.  It would also  
> provide better utilization of distributed caching, with CTAGs,  
> expiry headers, and the like all being there by default or easily  
> configurable in the web server.
>
>> From Paul's comments, I guess it would be possible to have an  
>> internal MapGuide WMS service consumed by something like  
>> TileCache, and then published out to Fusion from there... if it's  
>> possible to restrict WMS to a single host.  My problem with this  
>> is that my most common layer is probably the parcel base, and I'll  
>> need maptips, etc...
>
> I guess I could publish the visible base as a tileset, and then  
> publish an invisible layer on top of it for maptips and selection?   
> Unless invisible polygons are optimised out of the selection process?
>
> Jason
>
> ________________________________
>
> From: mapguide-internals-bounces at lists.osgeo.org on behalf of  
> Trevor Wekel
> Sent: Fri 2007-09-14 4:35 PM
> To: MapGuide Internals Mail List
> Subject: RE: [mapguide-internals] Tile maps...
>
>
>
> Hi Jason,
>
> A possible enhancement would be to define two map definitions for a
> "map".  The first definition would define the overlay/dynamic  
> layers and
> the second definition would be used only for the tiles.  I think they
> are separate layers in the new client framework so it may be  
> possible to
> implement.
>
> There would be some other implementation details like selection and
> query that would have to be worked out.  You may need to hit two  
> maps to
> find the selected/queried object.  This could be a little tricky but I
> don't think it would be impossible.  I suspect all the maps would also
> have to use the same coordinate system.
>
> Version 1.2.0 of the GETTILEIMAGE operation takes the resource id  
> of the
> map definition, the base map layer group name, the tile row and column
> and the scale index.  Authentication can be specified using  
> sessionid or
> username/password.
>
> A further enhancement to the "two layer" / "two map" approach would be
> to code up two different URLs for the overlay/dynamic and tiled  
> layers.
> This would allow us offload the base tiles to a completely separate
> server and web extensions.
>
> Thanks,
> Trevor
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org
> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason
> Birch
> Sent: Friday, September 14, 2007 4:38 PM
> To: MapGuide Internals Mail List
> Subject: [mapguide-internals] Tile maps...
>
> Hi all,
>
> I've been thinking (not a good sign) about how tile maps are  
> implemented
> in MapGuide.  I'm seeing some real limitations on how useful this is
> going to be for me because of the association of tile sets with  
> specific
> maps.
>
> With the new Fusion framework, I intend to have several dozen maps
> (themes), each using one of three tile set definitions.  With the
> current inclusion of tile groups in map definitions, this means that
> I'll have to have separate copies of these tile groups for each one of
> my maps.
>
> I would really like to see some way of abstracting tile groups from  
> map
> definitions.  Either through a new resource type that defines the tile
> group, or by allowing tiled maps to be referenced from regular maps,
> rather than redefined in each one.
>
> Thoughts?
>
> Jason
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|Paul Spencer                          pspencer at dmsolutions.ca    |
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|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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