Mostly, you are splitting up your line by whitespace, and split is a good tool for that job. But ... this variable length field you speak of throws a monkey wrench in the gears. Here is a regex that should do the trick: 
use strict;
use warnings;
use Data::Dumper;

my $str = 'May 16 11:17:12 system app: [id:id:id] Message [Class] [Pri
+ority:] {TCP} 111.1.1.64:1863 -> 222.2.2.155:55527';

# no need to use $1 $2 etc. when you can name them ;)
my ($mon,$day,$time,$app,$id,$msg,$proto,@ip) = 
   $str =~ /           # example match
      (\S+)\s+         # May
      (\S+)\s+         # 16
      (\S+)\s+         # 11:17:12
      ([^:]+):\s+      # system app
      (\S+)\s+         # [id:id:id]
      ([^\{]+)         # Message [Class] [Priority]
      (\{[^\}]+\})\s+  # {TCP}
      (\S+)            # 111.1.1.64:1863
      \s+\-\>\s+       #   (skip ->)
      (\S+)            # 222.2.2.155:55527
   /x;

print "$mon, $day, $time, $app, $id, $msg, $proto, @ip\n";

[download]
The important concept to take away from this is negation: (\S+) matches anything but whitespace, ([^:]+) matches anything up to a colon. I stored the two IP addresses in an array, your mileage will vary. Also, (update here) any complex regex such as this one should use the x modifier so it can be segmented and commented.

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

In reply to (jeffa) Re: Variable Length Parsing by jeffa
in thread Variable Length Parsing by ACiD

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