README-Datei für ebaywatch.pl aus dem Perl-Snapshot im Linux-Magazin 01/04:

Das Ebay-Skript ebaywatch.pl macht dem Jabber-Server zu schaffen. Es handelt
sich um einen Bug auf der Server-Seite, daher ist die Zeile
                                                                                
  $c->PresenceSend();                                                           

auskommentiert (s. Zeilen 108-110). Das tut der Funktion keinen Abbruch,
erspart aber den Jabber-Leuten einigen Ärger.

Hier die Mail des Jabber-Admins, der auf das Problem aufmerksam machte:

>>>>>>>>>>>>>>>>>

I am an admin on jabber.org, and have noticed a few of our users using
[ebaywatch.pl]. While it's a great use of technology glue (something Perl is
wonderful at), there is one issue in your script which is causing issues.

Your script uses the same jabberID for authenticating and for sending
messages. This is fine normally, however, your script also sends presence.
Which is SHOULD NOT do.. In order to send messages, your client connection does
not need to send presence, it just needs to authenticate. This is causing some
strange offline msg bounce loops with our current xdb backend (which we are
fixing). What happens is this:

1) your script logs authenticates
2) your script sends presence (bad!)
3) the jabber server starts sending you offline messages.
4) your script sends a message to the same userid.
5) the jabber server notices that the resource 'ebaywatcher' is the only
   resource online.
6) the jabber server sends the msg back to your script.
7) Meanwhile, the script logs off.
8) The server realizes that /ebaywatcher is no longer online, so it
   bounces the msg back to offline.

Note that this has a few side effects:
- lots of bouncing madness because the server tries to send
  ebaywatcher the msg.                                                                         
- the user can loose offline msgs since ebaywatcher just drops them.

I would appreciate it if you simply removed the:

$c->PresenceSend();

line of code from your script, and notify your users. This slight change
will cause it to be a much better netizen on the jabber network.

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