[OSM-dev] OSM XML declaration, JOSM, Osmosis et al.
Roland Olbricht
roland.olbricht at gmx.de
Thu Sep 22 05:37:57 BST 2011
> Is Overpass so geared for tools that don't care about
> uid/date/version/visible etc?
Actually, yes. Note that these tools include map rendering, routing, location
based search and probably every other tool that consumes the data. The data
model is: the state of the Planet database (or an excerpt) at a fixed point in
time, which makes perfectly sense.
Even keeping a database up to date would be possible without meta data: It
suffices to know the timestamp of the patches as a whole, not of every
individual element, despite the behaviour of possibly picky tools.
The old XAPI had mainly been suffering from a permanent shortage of hardware
resources. You now get a switch to download data three times faster if you
omit data that you discard anyway later - if you render a map, do routing, or
a lot of other useful things. This would even lower the burden on the still
hardware-constrained Overpass API server. A lot of users encounter that useful
but some can't make sense of the error messages somewhere later in the tool
chain. I can't and I won't rewrite every tool, but I can happily write in the
header whatever the tools expect. I simply asking for a consensus for the
things to write in the header.
Discussing the usefulness of the current history model is a different
question. As I got never an answer to an earlier post on that topic,
http://lists.openstreetmap.org/pipermail/talk/2011-September/060027.html
I assume that history is only a minor concern to most users.
Cheers,
Roland
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