[OSM-dev] OWL / API hacking this weekend
Paweł Paprota
ppawel at fastmail.fm
Wed Oct 24 11:13:50 GMT 2012
Hi,
Just as a heads-up - for the past week or so I've been doing some OWL
resurrecting myself and I hope to launch a demo instance in a day or two.
Current status:
* I tried to work with the C++ part of OWL, failed.
* I rewrote the database operations part as an Osmosis plugin[1]. As a
result, the C++ part of OWL is not needed anymore (or will not be needed
when there is full feature parity - soon).
* Database schema is a bit different for now[2]:
- Pgsnapshot (PostGIS) schema is used as a foundation instead of apidb
schema - this is mostly because of the fact that I wanted to have change
and changeset geometry in the database + there are couple of bonuses
like hstore instead of separate tables for tags.
- Row for single change now contains more information - old/new tags,
old/new geometry.
- There is geometry at the changeset level - this aggregates geometries
of all changes for a given changeset. That way bounding box query can
operate on 16 million rows (changesets) instead of 5-8 billion rows
(changes).
- Changes are currently not assigned to tiles as in original OWL - it is
not clear whether this is needed anymore - OWL could simply operate on
bboxes. Should be discussed more.
Immediate TODO:
* I am working[3] on the owl_viewer (Rails app) component to make it
compatible with the new schema. I will start with Ian's branch which has
Rails 3.x code in it and add simple Rails model - Changeset and Change.
* Find out if Matt wants me to call this thing OWL... as you can see,
there are major changes compared to the original code. I'm willing to
work towards a common vision for OWL and contribute to OWL instead of
spinning it into a separate project. So I would love to hear from Matt
and Ian what should be done to get this merged into upstream OWL.
Future TODO:
* Incorporate excellent functionality of the osm-watch software[4] in
some way - watching for changes in specific objects or objects with
specific tags (e.g. changes in schools in Berlin).
* Many more ...
[1] https://github.com/ppawel/osmosis/tree/changedb-plugin
[2]
https://github.com/ppawel/osmosis/blob/changedb-plugin/package/script/changedb_schema.sql
[3] https://github.com/ppawel/openstreetmap-watch-list
[4] https://github.com/cstenac/osm-watch
Paweł
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