ActiveX for ZIP/UNZIP

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by CarlRanson >> Wed, 15 May 2002 23:25:37 GMT

hi all,

Anyone used an active X library to add zip/unzip functionality to a Jade system?

recommendations? (preferably freeware).

CR

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by MITCHELL1 >> Thu, 16 May 2002 0:10:17 GMT

Haven't used ActiveX but we use PKZIP CommandLine 4.0 in the JADE Systems Manager, initiated either by ShellExecuted script or karma.dll call 'emCreateProcess'. But that may not be what you want to do.

--
Richard W Mitchell
Senior Software Engineer
Systems Management Development Centre
Jade Software Corporation Ltd
mailto: rmitchell@jade.co.nz

JADE Group trading as a division of Aoraki Corporation Ltd.
Visit our web site at www.cardinal.co.nz and news.jadeworld.com

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by cnwjhp1 >> Thu, 23 May 2002 8:01:21 GMT

We also use 'emCreateProcess' to run WinZip by command line. If you don't specifically need zip format, the compress method is much easier. -- jp

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by allistar >> Fri, 24 May 2002 1:30:41 GMT

On Thu, 23 May 2002 8:01:21 GMT, jporter@jade.co.nz (cnwjhp1) wrote:

As mentioned, if you don't need a "standard" compression format (like
zip or rar) there are other ways of doing it. We have had that need
for deployment software and decided to "roll our own" compression routines (in C++). The advantage is that you know exactly the type of data you are likely to be compressing, so you can bias the compression algorithm to favour that kind of data.

Regards,
Allistar. ------------------------------------------------------------------
Allistar Melville
Software Developer
Auckland, NEW ZEALAND

Greentree International,
Developer of Greentree Financial Software. ------------------------------------------------------------------

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by cdshearer >> Thu, 16 May 2002 1:12:58 GMT

Doesn't some of the internal compression stuff in JADE use zip libraries under the covers? Perhaps you can get a these and read/write to/from zip files?

Craig

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by MITCHELL1 >> Fri, 17 May 2002 0:16:53 GMT

Craig is correct : yes, depending on what you want to do, you could use the ::compress method of String or Binary. However this doesn't produce a file that you can use PKUNZIP or WinZip to expand.
--
Richard W Mitchell
Senior Software Engineer
Systems Management Development Centre
Jade Software Corporation Ltd
mailto: rmitchell@jade.co.nz

JADE Group trading as a division of Aoraki Corporation Ltd.
Visit our web site at www.cardinal.co.nz and news.jadeworld.com

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by CarlRanson >> Tue, 28 May 2002 1:58:47 GMT

For those that are interested, I found an especially good explanation of Huffman encoding at http://ciips.ee.uwa.edu.au/~morris/Year ... ffman.html

There is an applet that demonstrates the method quite clearly.
CR

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by allistar >> Sun, 2 Jun 2002 22:19:06 GMT

You'll find details of LZW compression on the net as well, which from
my tests compresses data a LOT better that huffman. Just don't expect
to be able to use it in the USA or some EU countries (Unisys still
have a patent on it will will last for anther couple of years). We
find that LZW compresses text much better that Huffman, and also
performs pretty well on binaries as well. An option is to huffman compress already LZW compressed data, you'll be able to squeeze a few more % out, although it will be slower.

Allistar. ------------------------------------------------------------------
Allistar Melville
Software Developer
Auckland, NEW ZEALAND

Greentree International,
Developer of Greentree Financial Software. ------------------------------------------------------------------