Data Compression within Jade Apps

[ConvertFromOldNGs]

by Harvey Taylor >> Mon, 12 Feb 2001 20:05:56 GMT

Has anyone has used data compression tools (such as PKWARE Data Compression Libraries) from within a Jade app?
If so, I would appreciate hearing from you

Harvey Taylor
Cardinal Healthcare

[ConvertFromOldNGs]

by Kevin Luck >> Mon, 12 Feb 2001 21:35:17 GMT

Just as a simple trial of the new command line add-on for Winzip 8.0.
I believe you need to have a registered copy of Winzip 8.0 to use this.

Cheers, Kevin

The Announcement blurb is copied below:-

--- WinZip Command Line Support Add-On Now Available ---

We are pleased to announce the release of the WinZip Command Line
Support Add-On. This add-on is available at no extra cost to all registered WinZip users and can be used on a trial basis along with evaluation copies of WinZip.

The add-on is available from

http://www.winzip.com/wzcline.htm

The WinZip Command Line Support Add-On requires WinZip 8.0 and Windows 95, Windows 98, Windows NT, or Windows 2000. If you are using an
earlier registered version of WinZip, please download and install the free upgrade to WinZip 8.0 from:

http://www.winzip.com/upgrade.htm

If you are using an earlier evaluation version of WinZip, please
download the current evaluation version from

http://www.winzip.com/download.htm

--- WinZip Command Line Support Add-On Features ---

The WinZip Command Line Support Add-On provides a command line interface that gives you the power of WinZip without the usual WinZip graphical user interface. The add-on allows you to use WinZip directly from the command prompt, batch files, and many application and system programming languages. An extensive set of command line options gives you pinpoint control over WinZip's actions.

The WinZip Command Line Support Add-On is ideal for quick zipping and unzipping from the command line and for automating repetitive tasks.



"Harvey Taylor" <htaylor@cardinal.co.nz> wrote in message news:bc0hz9SlAHA.270@news.jadeworld.com...
Has anyone has used data compression tools (such as PKWARE Data Compression
Libraries) from within a Jade app?
If so, I would appreciate hearing from you

Harvey Taylor
Cardinal Healthcare

[ConvertFromOldNGs]

by Krull >> Mon, 12 Feb 2001 22:33:48 GMT

Harvey,

Are you planning to compress data for storage in the database or do you need to compress external data?

The Binary and String compress/decompress methods provided in the JADE RootSchema use a PKWARE compression library under the covers.

[ConvertFromOldNGs]

by Carl Ranson >> Mon, 12 Feb 2001 22:55:44 GMT

slightly off topic....

I found a really clear explanation of huffman coding once....its actually deceptivly simple.

For those of you who are interested its at http://swww.ee.uwa.edu.au/~plsd210/ds/huffman.html
Includes a javascript animation that demonstrates the algorithm.

Cheers,
CR

[ConvertFromOldNGs]

by Wilfred Verkley >> Tue, 13 Feb 2001 21:26:51 GMT

Thats an interesting link.

According to this paper then, the maximum compression using this scheme is 1/8. Also, it would be fairly bad for compressing files where there is a even distribution of all the possible ascii values.

Im guessing zip uses a mixture of compression techniques, run-length encoding etc???

Wilfred.

[ConvertFromOldNGs]

by Carl Ranson >> Wed, 14 Feb 2001 1:42:02 GMT

Yes, im sure it does. There was also one I found that explaind LZH really well too, but I've lost the link. What suprised me is how simple these algorithms are.

I put off learning about this stuff for ages, cos it all seemed like complex voodo magic (dat powerful mojo). Shows the value of a clear explanation, eh?

CR

[ConvertFromOldNGs]

by Richard Mitchell >> Wed, 14 Feb 2001 22:13:32 GMT

Don't know if this helps, but in our JADE Systems Manager application I use the JADE compress and uncompress methods for compressing values for transmission via TCP.

I also use PKZIP25.EXE for file compression. PKZIP25.EXE is the commandline version of PKZIP. I run PKZIP25.EXE one of two ways : (1) by building a shell script (.bat or .cmd file) and running that using the Windows ShellExecute API, or (2) using a recently-added entry point in karma.dll which allows me to run a child process directly and capture the standard output for logging purposes.

Richard Mitchell
JADE Systems Group
JADE Direct