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===============
osm@spline Xapi
===============
Aim
============
We like to rewrite some parts of the XApi needed for our own application. Our
aim is not get a full implementation of the Xapi, but to answer only specific
requests, at low latency. For this subset of Xapi we want completly cover the
original api.
Requests
=============
This is a list of example requests, we want to optimize.
* xapi.spline.de/api/0.6/node[amenity=*]
* xapi.spline.de/api/0.6/node[highway=busstop]
* xapi.spline.de/api/0.6/node[bbox=-6,50,2,61]
* xapi.spline.de/api/0.6/node[amenity=hospital][bbox=-6,50,2,61]
a more formal description
-------------------------
We serve the node endpoint, but no others. We implment the tag based filtering,
for only one tag and a bounding box.
Dabase setup
=============
We use postgres 9.* with postgis 1.5. Postgres 9.0 is used becaus we need some
functions on hstores and postgis 1.5 is used for fancy geometry things.
To setup a database you first need a runing postgres 9.0 instance. I hope you know
how to do this.
Use
createdb osm
to create a database with name osm. Use
createlang plpgsql osm
to add plpgsql to your database. If you want to create a database user do so:
createuser <username>
Add hstore support for your database:
psql -d osm < /share/contrib/hstore.sql
Add postgis support for your database:
psql -d osm < /share/contrib/postgis-1.5/postgis.sql
Just do:
psql -d osm < /share/contrib/postgis-1.5/spatial_ref_sys.sql
Create the actual schema for osm data. For this step you need osmosis. If your
osmosis build is correct there should be a directory named pacakge/scripts where
you run:
psql -d osm < pgsql_simple_schema_0.6.sql
psql -d osm < pgsql_simple_schema_0.6_linestring.sql
Optional/stil to test:
psql -d osm < pgsql_simple_schema_0.6_action.sql
psql -d osm < pgsql_simple_schema_0.6_bbox.sql
For documentation on the schema read pgsql_simple.txt.
Import data from xml with:
osmosis --read-xml file="planet.osm.bz2" --wp host="localhost" password="TopSecretPassword" user="insertUserNameHere" database="osm"
Before or after import you may want to create a index or two. Examples below:
CREATE INDEX idx_nodes_tags ON nodes USING GIN(tags);
CREATE INDEX idx_nodes_tags ON nodes USING GIST(tags);
CREATE INDEX idx_ways_tags ON ways USING GIN(tags);
CREATE INDEX idx_ways_tags ON ways USING GIST(tags);
database shema (out dated)
================
We keep data in a highly specioaliced shema, that allows us to prevent tables
growing to big. And supports our requests at maximum speed.
| CREATE TABLE <tagname>:<tagvalue> (
| {bigint id}
| {longitude float4},
| {latitude float4},
| {object varchar}
| ) PRIMARY KEY id;
Implmentation
=============
Teilprobleme:
..............
1. Database import
mögliche Technologien:
* Osmosis- plugin
* selbst in python (Protobuf consumer, async pgsql schreiber)
2. Web API
..............
mögliche Technologien:
* node.js
|
