[OSM-dev] Call to mobile developers: OSM binary file format

Chris Browet cbro at semperpax.com
Fri Aug 8 09:48:03 BST 2008


>
>
> A binary XML format would be better to parse for an XML processor. But OSM
> data is pretty structured. The point is that for line transfers a pretty
> efficient format can be choosen that is totally unparsible by embedded
> devices.


The actual transfer is pretty much irrelevant here. The goal is to have a
format which RENDER fast.

Actually, the very notion of "parsing" should be avoided when doing mobile:
1) what takes milliseconds on a desktop can become seconds on mobile
2) parsing more-or-less presuppose loading everything in memory, which is
not doable on a device with < 128 Mb ram.

So the data should be "pre-parsed" and randomly accessible from storage to
be able to handle gigas of data. Only indexes could reside in memory for
efficiency.

>
> Since the subject suggest mobile developers; they might only be interested
> in a derrivative format that even *not* includes some information, and has
> a high focus on routing. Now I was always teached that if something
> focusses on one thing it will need to make compromises.


As for myself, I prefer to keep all information because I'm not focused on
routing as others. But I suppose compromise will have to be made.

- Chris -
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