[izpack-devel] Re: Pack File Size

Hal Vaughan hal at thresholddigital.com
Wed May 10 11:05:26 CEST 2006

I'm responding on the user list, but also sending it to the devel list 
because I really should have posted this to the devel list in the first 
place.  This is the 2nd time this week I typed in the list address on 
IzPack. (I wonder if it has to do with the all-nighters I've had to do 

On Wednesday 10 May 2006 04:05, Bartz, Klaus wrote:
> Hi Hal,
> you know, I do not use the web install feature, but I assume that
> I am the last who has made something at packaging.
> I have created a "normal" (non splited) installation three times.
> File size of jar files are allways the same. MD5 are not identically.
> A look with a hexeditor shows the diffs. There is an dir like
> entry for each contained file in the jar file where one byte differs
> also the time stamp shown by winzip will be identically.
> Additional there is a difference in the time stamp of
> meta-inf/Manifest.mf which will be generated by ant on the fly.
> Result will be that it is not possible to use a MD5 of jar files to
> detect that they contains the same.
> Generell this is a point of maintenance. You can do a little bit of
> maintenance with IzPack, but real maintenance is more.
> I am thinking about it since a long time because in fact we need it.
> But it is a complicated theme which needs a discussion and a design
> infront of implementation. May be we should begin a thread on the
> iszpack-devel mailing list.

The differences are only one or two bytes in length.  I won't have time 
to check the time stamp for a while, but I guess I'll just have to 
assume it will always be the same length.  It is possible, but 
unlikely, that the length of differences could be a result of the 
encryption stream I'm using, but then it should only effect the pack 
I'm encrypting.

I don't know if my situation is unique, but I have to prepare a separate 
install for each of my clients, since one pack includes individualized 
passwords for each client.  That means each time I get a new client, I 
have to create a new web install and standard install, upload the web 
install and put the standard install on a CD.  Since I have two large 
packs, that means it takes a long time to upload.  What I was thinking 
about doing was uploading the two big packs, using symlinks so I had 
only one copy of each big pack, and not uploading a new copy until 
something in the pack changed.

At this point I think I'm going to be using rdiff to upload a patch file 
containing only the differences.


> Cheers
> Klaus
> >-----Original Message-----
> >From: izpack-users-admin at berlios.de
> >[mailto:izpack-users-admin at berlios.de]On Behalf Of Hal Vaughan
> >Sent: Tuesday, May 09, 2006 7:52 PM
> >To: izpack-users at berlios.de
> >Subject: [izpack-users] Pack File Size
> >
> >
> >I've been doing some test compiles and working with pack files and
> > the install.jar that IzPack creates.  I will have to make my web
> > install available on my web site (obviously), and that means I will
> > have to upload it to the site.  There are two packs in each install
> > that are big (they are OpenOffice for Linux and Windows).  It takes
> > about 30 minutes to upload one of these files using scp.
> >
> >To avoid unnecessary uploads, I figured I could check the MD5
> >sum of the
> >file on my website with the MD5 sum of the file I've created.  If
> > they match, I'm re-creating what I had and there's no reason to
> > upload. That way I can change around packs and only have to upload
> > the ones I don't alter (the uploading is an automatic script).
> >
> >While experimenting with creating the install.jar file, I've
> >found that
> >even when I do NOT change a thing on the files that are included,
> > the length of the file changes.  I don't see why this should
> > happen.
> >
> >What is included in the Install.jar file or the individual packs
> > that would change the length?  Why is it I can create the same
> > install 3 different times and get 3 different file lengths?  (Once
> > I saw the different file lengths, I didn't even bother to check the
> > MD5 sums.)
> >
> >I'd like to know what causes this because I may want to alter it in
> > my copy of IzPack.
> >
> >Thanks for any info on what might make the same install compile
> >differently each time I do it.
> >
> >Hal
> >_______________________________________________
> >izpack-users mailing list
> >izpack-users at lists.berlios.de
> >http://lists.berlios.de/mailman/listinfo/izpack-users
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