[OSM-dev] Timestamp in PBF files

Frederik Ramm frederik at remote.org
Mon Dec 3 23:09:16 GMT 2012


Hi,

On 03.12.2012 22:27, Jochen Topf wrote:
> Why the "osmosis" in there? That seems rather strange to me. Either it is some
> general thing that works with all programs, then it shouldn't be named after a
> specific program. Or it is not, then it shouldn't be in a general file standard.

It is the replication technology used by Osmosis on the server side. It 
works with all programs that use the Osmosis algorithm. It doesn't work 
with every thinkable replication mechanism because those might require 
other data. Trying to invent something "future proof" seldom works.

For example, the way the directories are structured below the 
replication URL 
(http://planet.openstreetmap.org/replication/minute/000/118/578.osc.gz) 
is something specific to the way Osmosis handles its replication; a 
program that consumes these files needs knowledge about that.

If you wanted to encode some kind of generic replication information 
then you'd probably boil it down to a simple string field called 
"replication_information" and that would then contain something like 
"replication_type=osmosis sequence_number=1234 
url=http://something/replication/minute" or so.

That would be possible, but it would force every single writer/consumer 
of these files to serialize/deserialize the replication information 
string (tabs or spaces? spaces allowed after the equal sign or not? 
order significant? type=osmosis or type=Osmosis? ...) - making them 
top-level fields saves us from that.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"



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