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The Java XAPI

Posted by iandees on 26 January 2011 in English.

I recently released the first version of a mostly-complete Java implementation of the XAPI server. The source code is available on my GitHub with a readme describing generally how to get it set up.

Running this database with a full-planet requires some large, fast disks. The database is roughly 350GB and is slowly increasing:

CPU and memory usage are useful for the initial import (indexing especially), but any subsequent queries will be limited by the disk speed.

Feel free to use it! Serge W. created an XAPI UI framework that I set up at http://openstreetmap.us/uixapi/xapi.html to build the XAPI query URLs.

At the moment, the Java XAPI seems to have a problem returning relations and doesn't implement child element predicates or special tags. If you find other problems, please file a bug.

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Discussion

په 26 January 2011 په 15:13 باندې د Firefishy تبصره

Stats for xapi.osm.org for 25 Jan 2011:
tags:
@user= - 27 queries from 12 IP addresses.
@uid= - 3 queries from 2 IP address.
@changeset - 1 query

په 26 January 2011 په 16:00 باندې د Harry Wood تبصره

You didn't actually mention the base URL for your new service: http://openstreetmap.us/xapi/api/0.6/

It works! Example: All the libraries in London : http://openstreetmap.us/xapi/api/0.6/*[amenity=library][bbox=-0.57,51.24,0.31,51.75]

Great work!

په 26 January 2011 په 16:24 باندې د Tom Chance تبصره

Great, I'll give it a go.

په 26 January 2011 په 16:37 باندې د Maarten Deen تبصره

Looks promising. But the performance with large bboxes isn't there yet.
Harry Wood's example works for me, I can also download banks in a 0.2x0.2 bbox, but trying to get banks for the whole of the Netherlands does not work yet. I get a "504 Gateway Time-out" message.
My test URL: http://openstreetmap.us/xapi/api/0.6/*[amenity=bank][bbox=2.5,50.7,7.2,53.6]

په 26 January 2011 په 16:42 باندې د iandees تبصره

The machine restarted itself at 16:00UTC or so, which lines itself up with your request fairly well.

But yes, large bounding box queries are mildly slow -- I don't remember them being particularly fast on the other system, though.

په 26 January 2011 په 16:48 باندې د Tom Chance تبصره

I get the same message trying to download all power generators in the UK.

http://openstreetmap.us/xapi/api/0.6/*[power=generator][-6.5,49.68,2.67,61.31]

Just London works fine:
http://openstreetmap.us/xapi/api/0.6/*[power=generator][bbox=-0.5
1,51.20,0.35,51.80]

په 26 January 2011 په 16:53 باندې د iandees تبصره

It bounced a few more times and is down hard now. There appear to be some ECC memory errors, but I put fresh memory in a while back. Looks to be a bad motherboard. Thanks for the stress test, everyone!

په 27 January 2011 په 23:13 باندې د Geonick تبصره

Is this XAPI UI really reflect the syntax of XAPI? Currently there is only one tag predicate. Isn't it possible to query more than one, like

http://openstreetmap.us/xapi/api/0.6/*[amenity=parking][capacity:disabled=*][bbox=-0.57,51.24,0.31,51.75]

Actually, even the OSM wiki leaves this question open:
osm.wiki/Xapi#Predicates

It would be nice anyhow that the wiki page get's enhanced with a real syntax definition.

په 28 January 2011 په 01:24 باندې د iandees تبصره

@Geonick: yes, this really does follow the XAPI query syntax. You can indeed supply multiple tag predicates. It will eventually be possible to include multiple bounding box predicates, but at the moment I only allow one.

په 9 March 2011 په 21:01 باندې د Katzman تبصره

Two things:
- so the possibility to enter multiple tags is not implemented yet, right?
- is it possible to do non-case sensitive search on the values, such as icao=lklt would return any combination of LKLT, lklt, LKlt, LkLt, etc.?

Thanks!

په 9 March 2011 په 21:03 باندې د iandees تبصره

@Katzman:

1. It is possible to enter multiple tag predicates:

[amenity=foo|bar] := "amenity"="foo" OR "amenity"="bar"
[amenity|leisure=foo] := "amenity"="foo" OR "leisure"="foo"
[amenity=foo][area=bar] := "amenity"="foo" AND "area"="bar"

2. Not at this time.

په 21 March 2011 په 19:34 باندې د Arminus تبصره

Very nice ! Any updates on the relation problem ?

په 31 March 2011 په 17:45 باندې د Tilo تبصره

Is the jxapi down at the moment?

I want to prevent denied download requests before the request is sent. How is it handled, if a bbox is too large? like this?
[bbox=West,South,East,North]
if difference(West,East)*difference(South,North) > 10 --> denied
if difference(West,East)*difference(South,North) <= 10 --> accepted

Is it planned to allow larger bboxes than 10 sqaredegrees in future?

Thanks!

په 31 March 2011 په 17:48 باندې د Tilo تبصره

[bbox=West,South,East,North]
if difference(West,East)*difference(South,North) > 10 --- denied
if difference(West,East)*difference(South,North) <= 10 --- accepted

په 31 March 2011 په 17:51 باندې د iandees تبصره

@Tilo: No, the jxapi is/was not down. It was getting inundated with duplicate requests so the process queue was very long. I restarted postgres to clean out the queue.

I compute the sum of the areas of the requested bounding box(es) and compare that to 10. If larger, 500. If less, let it through.

There are no plans to do areas larger than 10 square degrees. As you can see already the hardware has a hard enough time keeping up.

په 31 March 2011 په 17:51 باندې د Tilo تبصره

damn,
the third line was supposed to look like this (now, in words):
if difference(West,East)*difference(South,North) is less or equal 10 then accepted

په 31 March 2011 په 17:59 باندې د Tilo تبصره

Great! thanks a lot.

په 1 April 2011 په 04:36 باندې د Tilo تبصره

I just tested a little smaller request than 10 square degrees with the request below (9.8 sqdeg) and ran into an Error. see the message below from http://jxapi.openstreetmap.org/xapi/admin/stats

ERROR way[boundary=administrative][bbox=8,48,10,52.9] 144 30 mins 32.909 secs

What is wrong with the request? Is there another reason for denial than the bounding box?

Thanks

په 1 April 2011 په 05:12 باندې د Tilo تبصره

this worked:
way[boundary=administrative][bbox=8,48,10,52] (221655 elements)

but this didn't:
way[bbox=8,48,10,52]

???

په 5 April 2011 په 09:44 باندې د malcolmh تبصره

Bounding boxes that straddle 180 E/W are rejected. I assume this is because West > East. Is this a bug or a feature?

په 5 April 2011 په 10:47 باندې د iandees تبصره

This is not a good place to make bug reports. Do that here: https://github.com/iandees/xapi-servlet/issues

په 12 April 2011 په 20:05 باندې د iandees تبصره

********THIS IS NOT A GOOD PLACE TO MAKE BUG REPORTS************. Do that here: https://github.com/iandees/xapi-servlet/issues

په 17 April 2011 په 12:36 باندې د Langlaeufer تبصره

sorry, I do not like to register there!

په 27 April 2011 په 06:59 باندې د Bryce C Nesbitt تبصره

Great! Thanks for making progress brining xapi back to life!
It would be nice if the status page at http://jxapi.openstreetmap.org/xapi/admin/stats gave details on the ERROR, rather than simply saying ERROR.

په 28 April 2011 په 02:51 باندې د Tilo تبصره

I agree with Bryce on both!

about 14 days ago this request: *[bbox=8.173,49.815,9.173,50.554] worked fine.
size 523 MB

Yesterday in the afternoon and today (at night) I always got an error. I tried 5 times each. Neither the bbox limitation of 10 sqare degrees (less than 2 sqdeg here) nor the syntax should be a problem in this request. What are the other limitations which cause an error?

Have new limitations been implemented between apr,14 and apr,28?

په 28 April 2011 په 02:52 باندې د iandees تبصره

********THIS IS NOT A GOOD PLACE TO MAKE BUG REPORTS************. Do that here: https://github.com/iandees/xapi-servlet/issues

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