[izpack-users] Using Compression in Packs

Bartz, Klaus Klaus.Bartz at coi.de
Thu May 4 11:39:52 CEST 2006

last year I have implemented the compressor stuff.
At default we use the "normal" deflate compression of a jar file.
Our server installation will be compressed from ~700 MB to ~350 MB.
If nothing compresses, there is something wrong.

I have also seen at implementation time, that bzip2 is not much
better as deflate; 3 - 5 %. I do not know why. May be this is related
to the point that IzPack often used for java appls which contains
already comprest jar files.

I had played a little bit with LZMA (7zip); it was ~ 25 % better as deflate.
But up to know I have had no time to write a filter output stream 
which compresses with LZMA. 
The java impl of LZMA self is not filter output stream orientated.
In the current design of pack compression we cannot use the 7zip
classes. May be it will be possible to write a wrapper around the classes
which wrappes it to an filter output stream. LZMA will be sometimes
very slow (much slower as bzip2) at encoding...
If some one will do the work - to write an encoder as filter output stream
and an decoder as filter input stream using 
interface com.izforge.izpack.compressor.PackCompressor
as integration wrapper - I will be very happy.

Never heard of a compression which is reproducable 60% better as deflate.
Means not only for special cases used; e.g. CCITT T.6 is better as deflate, 
(can be more than 60 %) if you compress a BW image without noise, but at 
halftone images CCITT T.6 will compress nothing. And an exe you cannot compress
with CCITT T.6.
Will be very nice if some one can send me the sources or a link to the
description of the (non patent) algorithm.

On the other hand, it is possible that I have made a mistake at
implementation. Please look into package com.izforge.izpack.compressor.
There are the related classes. 



>-----Original Message-----
>From: izpack-users-admin at berlios.de
>[mailto:izpack-users-admin at berlios.de]On Behalf Of "Schröder Frank, HH"
>Sent: Thursday, May 04, 2006 10:50 AM
>To: 'izpack-users at berlios.de'
>Subject: AW: [izpack-users] Using Compression in Packs
>Hi Hal,
>I wrote a similar mail a few weeks ago (see below).
>If you have the time to analyze and fix the problem or need some
>support (I'm not an expert in this field, too) send me your ideas.
>best regards
>Frank Schröder
>FJA Hamburg
>Süderstr. 77
>20099 Hamburg
>Tel  040 / 236005-51
>Fax 040 / 236005-56
>mailto:frank.schroeder at fja.com
>Von:	Schröder Frank, HH
>Gesendet:	Montag, 10. April 2006 16:06
>An:	'izpack-users at lists.berlios.de'
>Betreff:	how to use compression?
>is there anyone who knows how to use the different compressors 
>in IzPack?
>I played around with "raw" and "bzip2" and different levels, 
>for example
>compile ... -c bzip2 -l 9
>but I saw no (significant) influence on the installers size 
>(only on the
>time to build it).
>For the application I want to pack, IzPack produces an 170 MB Jar. 
>(with InstallShield I got an 60 MB exe!)
>> -----Ursprüngliche Nachricht-----
>> Von: izpack-users-admin at berlios.de 
>> [mailto:izpack-users-admin at berlios.de] Im Auftrag von Hal Vaughan
>> Gesendet: Dienstag, 2. Mai 2006 20:24
>> An: izpack-users at berlios.de
>> Betreff: [izpack-users] Using Compression in Packs
>> When I was working on finding a way to integrate encrypting packs I 
>> remember looking over some of the jar handling routines for 
>input and 
>> output.  I haven't done a lot with jars and IO is not one of 
>> my strong 
>> points, but it appears to me that there is no compression 
>used at all 
>> in creating packs or the entire install jar file.  Is this a 
>> deliberate 
>> decision and is there a reason for it?
>> Would there be any interest in making a small change to add 
>> compression?
>> Would there be interest in the ability of the developer to pick a 
>> desired level of compression?
>> I started thinking about this when realizing that one of the 
>> 4 packs I 
>> need for my program is 91 MB and another one I haven't quite 
>> with will likely be even larger.  It took over half an hour 
>to upload 
>> this 91MB pack to my web site in a test run today.  After 
>> dealing with 
>> that I would much rather wait longer for the pack or jar file to be 
>> created and have a smaller file than to have such a large pack.
>> Thanks!
>> Hal
>> _______________________________________________
>> izpack-users mailing list
>> izpack-users at lists.berlios.de 
>> http://lists.berlios.de/mailman/listinfo/izpac> k-users
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