[CM Dev] Enhancing server performance with multi-tile requests

[Jaak Laineste]

Hi,
 This is perfectly valid point. We have solved it with the Mgmaps lib SDK
and CloudMade tiles this way, that we set up own "tile streaming" server to
AWS EC2, so it has superfast connection to CM tile server, and I am doing
the tile proxying there just like you describe. I must admit that I got also
some inspiration from the google's mobile maps app :). 

 You can compare different map reading options, direct 64x64 tiles or the
multi-tile requests (we call it "streamed") with on-line web runner demo at
http://www.nutiteq.com/libsamples.html#BasicMapperapplication . Start the
app from web (it starts microemulator automatically), you see performance
with default map, which is CM 64-pixel individual tiles. Select Menu >
Change map > select CloudMade streaming (via Nutiteq) and see speed then.
Difference is quite big, to say the least. Not worse than with google maps
mobile.

 In terms of Lib SDK Java code the multi-tile map is selected like
following: 
mapItem.setMap(new
NutiteqStreamedMap("http://aws.nutiteq.ee/mapstream.php?cmkey=YOUR-CLOUDMADE
-KEY&", "CloudMade", 64, 0, 19));

 The streaming script supports also parameter s for CM style number (default
s=1), so you can define base URL as
"http://aws.nutiteq.ee/mapstream.php?cmkey=YOUR-KEY&s=2&" for mobile tiles.
However, this proxy is for development (and demos) only, and unsupported. 

 We have also public document describing of the streaming API from J2ME Lib
SDK point of view at
http://www.nutiteq.com/system/files/MGMaps%20server%20API%20specification_01
1208_v3_0.pdf

 Of course it would be even nicer if CloudMade had own streaming API for
mobile tiles, so I would not need to keep own server up :)

/Jaak Laineste
Nutiteq



> I have been experimenting with a mobile Jave ME app that displays 64x64
> tiles read from the CloudMade server at tile.cloudmade.com .
> I noticed that Google Maps for mobile phones performs much better than
> my app on the same phone, and decided to investigate why.
> 
> So I wrote a quick & dirty server benchmarking application to compare
> performance of the Google Maps server for mobile apps (the one that
> serves 64x64 tiles) and the CloudMade server.
> 
> When requesting one tile at a time, they perform about the same.
> 
> BUT here's the catch : Google Maps has an API that allows to ask for
> _several_ tiles in one request.
> When requesting tiles by sets of 20, I got a substantial performance
> increase as shown below :
> 
> CloudMade, 1 tile per request : 1.9 tiles per sec
> Google Maps, 1 tile per request : 2.1 tiles per sec
> Google Maps, 20 tiles per request : 13.8 tiles per sec <=== pretty good
> !!
> 
> So I'm thinking, wouldn't it be worth a try to make the CloudMade
> server
> accept multi-tile requests ?
> 
> Though not familiar with the internals of the server, I have the
> impression that this would not be too complicated
> to implement- the way they do it at Google is, you POST specially
> formatted binary
> request saying N (number of tiles), and then N times (zoom, x, y).
> 
> If it works, this would allow mobile apps to update their maps much
> faster, because as it stands it take several seconds for
> the map to be displayed completely, whereas the Google Maps application
> updates almost in real time as you scroll.
> 
> (I hope I'm not coming across as dissing CloudMade vs Google Maps,
> because that is not at all my intention, I'm just
> exploring the limits of what's possible with a Java phone and a GPRS
> connection).
> 
> Anyway- maybe you guys have already thought about this, but I didn't
> find anything in the mailing list archive (though, granted, I
> didn't read ALL of it). And, I'll be glad to help if I can...
> 
> Nick.
> 
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