[OSM-dev] Mobile binary protocol

Adam Boardman osm-dev at adamboardman.co.uk
Tue Mar 18 14:07:15 GMT 2008


> If you do not need to issue write requests to the server, then it would 
> unnecessarily clog the one big bottleneck we have (the central server). 

Adding writes is a distinct possiblity. There is no reason not to permit 
editing on mobile devices, or by non-mobile devices using the Osm 
Binary Format, the amount of memory used by a bmap api call will be much 
less, saving resources at both ends.

> If you can manage to download stuff from elsewhere

The PHPProxy code supports (thanks to Paul Fox) using the osmxapi so 
those who install that can currently choose where they get the data 
from.

It should be a free choice for app writers whether their app uses the 
main api, osmxapi or a caching proxy. We should have binary support 
within all three.

The caching proxy used by WhereAmI caches the OBF data for one week 
(v0.09 onwards, before that it was 8 hours), in a future version it will 
support downloading delta's between previous and this weeks versions to 
provide updates. When WhereAmI supports editing this will be a special 
mode that you flip into at a high zoom level, which will then request an 
upto the minute delta against what is already downloaded, and provide 
changes back. I think WhereAmI will always work through a proxy to 
enable the caching of what clients have downloaded, so main API support 
is not esential, but would be nice and would avoid unneeded bandwidth 
(and XML creation/parseing time) between the API and the proxy server.

What other apps do is upto other app writers...

Cheers,

Adam.




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