[fusion-users] MapGuide HTTP tiles with Fusion?

[Jason Birch]

Cool.  

This would really help in working around MapGuide's single-threaded
raster provider... but also would allow me to maintain a single base map
that is used by multiple overlays; way less storage, etc, etc.  Hmm.
Ideally, the appdef would allow me to define base maps that would be
available to all "themes". 

I wonder if the tile cache root URL would be better specified at the
appdef map level rather than in the config.

The reason I think this is that:

 - in some cases you'd want multiple hosts (tile1, tile2, tile3) to work
around HTTP connection restrictions

 - you may want to pull tiles from different http sources from the same
Fusion instance.

I guess you could store the LoadMap map properties in the AppDef too for
HTTP-based MapGuide base maps.  If you're compiling, it'll get converted
to JSON anyway :)

In my use case, selection and maptips would not be performed on the base
layer, just on overlays.
 
Jason


-----Original Message-----
From: Mike Adair [mailto:madair at dmsolutions.ca] 
Sent: March-06-09 11:05 AM
To: Zac Spitzer
Cc: Jason Birch; fusion-users at lists.osgeo.org
Subject: Re: [fusion-users] MapGuide HTTP tiles with Fusion?

Once the OpenLayers MapGuide layer includes the patches for #1622 and 
#1756, then yes in theory using tiled base layers would be possible.  I 
will update Fusion trunk with that patch included eventually.  I did 
some quick tests to see what would be involved.

I tried setting a regular MG tiled layer as the base layer with a MG 
overlay placed on top of that and it works in theory (I ran into some 
visibility issues that I will look into) but it is definitely possible 
to do.

Setting an http cache as the base layer (alone or combined with others) 
isn't currently supported but worth doing in my opinion.  However there 
are a few issues to be decided:

- Fusion will still require a LoadMap call to get the parameters for the

map (extent, scales, layers, etc.).  This can either use the existing 
LoadMap call using the tiled MapDefinition resource, but this still 
requires an instance of MapGuide to be available.  There are other 
server calls that would require a MapGuide instance (e.g. selection, 
maptips) so this may not be a big issue.  The alternative is to have a 
static json file which is similar to the LoadMap response that can be 
used to describe the map.

- the tile cache root URL needs to be specified somewhere, I'm thinking 
that config.json is probably the best place for that.

Comments?

Mike