Referate FOSSGIS 2010

Sourcepole war an der deutschsprachigen FOSSGIS-Konferenz 2010 in Osnabrück gleich mit drei Vorträgen vertreten.

Die Präsentationsunterlagen können hier heruntergeladen werden:

• GIS mit Ruby on Rails
• Performance und Verfügbarkeit von WMS-Servern
• SpatiaLite, das Shapefile der Zukunft?

Die detaiilierte Anleitung für den WMS-Performance Test kann im OSGEO-Wiki nachgelesen werden.

Besten Dank für das sehr positive Feedback!

Occassionaly we’ve been seeing messages like:

spam acl condition: error reading from spamd socket: Connection reset by peer

in /var/log/exim4/paniclog

But lately the problem has become much more persistent. I found out, that there’s some arsehole spammer sending us 500K spams every ca. 70 minutes. From /var/log/mail.log:

Jul 17 08:52:32 mail spamd[477]: spamd: identified spam (7.9/5.0) for spamd:1004 in 288.5 seconds, 505669 bytes.

Now since spamassassin would take that long (nearly 5 minutes!!!) to find out whether that mail is a spam or not, exim would simply timeout it’s connection to spamassassin and the result was the message seen above.

What I did was to use sa-compile to compile the SA rules to “native code” and to enable “Rule2XSBody”, which on Debian lives in /etc/spamassassin/v320.pre.

This seems to make SA quite a lot faster and to use less CPU.

If this won’t help we could also restrict the maximum size of messages to scan.

Yours Tomáš Pospíšek

Die internationale Open Source GIS-Konferenez FOSS4G findet dieses Jahr vom 6.-9. September 2010 in Barcelona statt.

Sourcepole ist mit drei Vorträgen vertreten:

• Comparison of Open Source Virtual Globes
• Performance and statistical analysis of WMS servers
• SpatiaLite, the Shapefile of the future?

Zusätzlich unterstützen wir den QGIS-Workshop und nehmen mit dem QGIS-Mapserver an WMS Performance Shootout teil.

Since I found Michel de Boer’s explanation of many of the fundamental SIP concepts in his 2005 dutch presentation of the Twinkle SIP phone very short and easy to follow - contrary to a lot of other material about SIP out there - I’ve translated it to english.

Here it is: Twinkle - a SIP softphone for Linux

Well, sometimes one wonders why people write tools that wheight a megabyte, when it’s easy to stick together one or two tools with a script and have the same thing.

Here’s a ruby script that generates a ping latency graph (target is google):

#!/usr/bin/ruby
#
# based on
#   http://oss.oetiker.ch/rrdtool/prog/rrdruby.en.html example
# with help of the tutorial
#   http://oss.oetiker.ch/rrdtool/tut/rrdtutorial.en.html
# and the docu
#   http://oss.oetiker.ch/rrdtool/doc/rrdcreate.en.html
# 
# placed in the public domain by Tomáš Pospíšek

require "RRD"

$rrd    = `mktemp /tmp/tmp.XXXXXXXX`.chomp
$grafik = `mktemp /tmp/tmp.XXXXXXXX`.chomp
$start  = 0

def now()
  Time.now.to_i
end

def create()
  $start=now()
  RRD.create(
    $rrd,
    "--start", "#{$start - 1}",
    "--step", "#{1}",       # every 1s
    "DS:pinglatency:GAUGE:10:0:200", # 10s of missing data are OK, min=0, max=200 (ping time)
    "RRA:AVERAGE:0.5:1:#{60*30}") # 60 seconds * 30 minutes
  puts "RRD database created #{$rrd} at #{$start}"
  puts "Your graph is at #{$grafik}"
end

def ping_latency
   `ping -c 1 -n -w 1 google.com` =~ /.* time=(\d+)/
  # 64 bytes from 74.125.43.147: icmp_seq=1 ttl=52 time=31.6 ms
  return $1
end

def update()
  puts "updating #{$rrd} with #{now()}:#{ping_latency()}"
  RRD.update($rrd, "#{now()}:#{ping_latency()}")
end

def generate_gfx()
  # puts "generating graph #{$grafik}"
  RRD.graph(
   "#{$grafik}",
    "--title", " Ping latency to Google",
    "--x-grid", "SECOND:10:MINUTE:1:MINUTE:2:0:%X",
    "--start", $start.to_s,
#    "--end", # -> now
    "--interlace",
    "--imgformat", "PNG",
    "--width=450",
    "DEF:pinglatency=#{$rrd}:pinglatency:AVERAGE",
    "AREA:pinglatency#00b6e4:ms")
end

#main
create()
while(true)
  update()
  generate_gfx()
  sleep 1
end

It generates a graph like this:

Das erste deutschsprachige QGIS User Meeting in Bern war mit rund 80 Teilnehmern ein grosser Erfolg.

Die Folien der Präsentation des OpenLayers-Plugin sind hier erhältlich.

Die gesammelten Präsentation werden auf der QGIS-Homepage veröffentlicht.