ZIP code module without DLL dependencies???

[The Frog]

Hi Everyone,

I am trying to find a solution for handling zipped data without the
need to ship / install any DLL files with the database. Does anybody
know of code to handle ZIP files that does not require any external
references? If I can ship it 'built-in' as either a class module or
standard module then that would be perfect.

Any help would be greatly appreciated.

Cheers

The Frog

[Chuck Grimsby]

On Thu, 29 Nov 2007 00:59:26 -0800 (PST), The Frog
<Mr************ @googlemail.com wrote:

>I have already secured the
payload. I am really just looking for a way to crush a file to its
smallest possible size before transmission.
Any ideas?

Sorry for the day's delay in replying. I was searching my archives.
I half-remember playing with some code that duplicated the LZH
compression scheme, but I can't seem to find any in a format I can
still open. The files I have are (I think) in the old Pro basic 7
format, that I didn't save as text. (I don't think I have a computer
that will still run that old programming language, darn it!)

You might want to spend some time at Planet Source Code or some other
site like that to see if they have any thing you can use.

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[Stuart McCall]

"Chuck Grimsby" <c.*******@worl dnet.att.net.in validwrote in message
news:sm******** *************** *********@4ax.c om...

The files I have are (I think) in the old Pro basic 7
format, that I didn't save as text. (I don't think I have a computer
that will still run that old programming language, darn it!)

If you mean Microsoft Basic 7 Pro, I do. If you'd like to mail them over
I'll see if I can send you the text version. Remove 'un' from my addy to get
my real address. Might not be instant - I may have to play with the m/c to
boot it. For one thing the CMOS battery will be dead by now, but I have the
hard drive parameters, so I ought to be good to go.

[The Frog]

Hi Guys,

Thanks for getting back to me. I have managed to locate the source
code claiming to be a powerbasic implementation of the ZIP Deflate
algorithm. I will send you a copy via email.

If I can reverse engineer it into a VBA implementation I will. I just
have to get the time to sit down quietly and do it. I will then post
the resultant code here in this newsgroup so we dont ever lose it :-)

Thankyou both for your help with this. I appreciate the guidance.

Cheers

The Frog

[Chuck Grimsby]

On Sat, 1 Dec 2007 00:49:09 -0000, "Stuart McCall"
<sm*****@myunre albox.comwrote:

>"Chuck Grimsby" <c.*******@worl dnet.att.net.in validwrote in message
news:sm******* *************** **********@4ax. com...

>The files I have are (I think) in the old Pro basic 7
format, that I didn't save as text. (I don't think I have a computer
that will still run that old programming language, darn it!)

If you mean Microsoft Basic 7 Pro, I do. If you'd like to mail them over
I'll see if I can send you the text version. Remove 'un' from my addy to get
my real address. Might not be instant - I may have to play with the m/c to
boot it. For one thing the CMOS battery will be dead by now, but I have the
hard drive parameters, so I ought to be good to go.

Actually, I found a computer in my "collection " that could run BC7 (it
even still had windows 3.11 on it!), but the file isn't a BC7 file.
Nor a GW Basic file. It may be GFA Basic. I think I still have the
disks for that... If it's Pure Basic, or Real Basic, I'll have to dig
a bit deeper into the archives.

'Course it may be some other language... Hmmm... I wonder if it's
VB3? This could get interesting!
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[The Frog]

Hi Chuck,

I might just have to go through the whole lot on paper. I might even
try and locate an old dot matrix printer for the 'feel' of the
situation... I think there is an old Star NL-10 alround here
somewhere...

I figure that as long as I can follow the individual steps required to
make the thing work then I can probably reverse engineer it into a VBA
version. My interest is really the compression more than anything
else, so the 'file' stuff is secondary to my purposes but would be
good to have in there. I'll see what I can come out with over the
weekend.

By the way, do you know of any implementations (again DLL-less) in VBA
for doing error correction routines such as Reed Solomon? I started to
have a bit of a dig through and have found some C code to do the job
of encoding, but not for decoding. Adding Forward error correction
(FEC) capabilities would potentially be the last of the hurdles I have
to overcocme. I thought that since it has been around so long someone
might have done it in pure VB / VBA but I cannot locate anything
easily on Google. Do you know of anything?

Cheers

The Frog

[Chuck Grimsby]

On Wed, 5 Dec 2007 01:41:16 -0800 (PST), The Frog
<Mr************ @googlemail.com wrote:

>Hi Chuck,
I might just have to go through the whole lot on paper. I might even
try and locate an old dot matrix printer for the 'feel' of the
situation... I think there is an old Star NL-10 alround here
somewhere...
I figure that as long as I can follow the individual steps required to
make the thing work then I can probably reverse engineer it into a VBA
version. My interest is really the compression more than anything
else, so the 'file' stuff is secondary to my purposes but would be
good to have in there. I'll see what I can come out with over the
weekend.
By the way, do you know of any implementations (again DLL-less) in VBA
for doing error correction routines such as Reed Solomon? I started to
have a bit of a dig through and have found some C code to do the job
of encoding, but not for decoding. Adding Forward error correction
(FEC) capabilities would potentially be the last of the hurdles I have
to overcocme. I thought that since it has been around so long someone
might have done it in pure VB / VBA but I cannot locate anything
easily on Google. Do you know of anything?

Believe it or not, my *only* printer is a Star NX-1000. It's in the
top of the garage though... I keep it around "just in case", but I've
never found a need for it, or to even hook it up for that matter!
(It's amazing how little you find a "need" for a printer when there
isn't one available.)

As for error correction and Reed-Solomon, I can't say as I ever played
with Reed-Solomon. Simple CRC checking is all I ever used, and of
late, I've just been passing it through ImageHlp.dll and letting it do
the CRC calculations. It's been quite a while since I've had to do
any *serious* CRC calculations with data streams.

You might want to look for routines for creating pdf417 bar codes. If
memory serves, they use Reed-Solomon. ID automation might have a few
code samples. (Obviously, you shouldn't use their code directly as
I'm sure it's copyrighted.)

A search of Google Groups or planet source code should reveal quite a
few samples of CRC code as well. Just watch out for the ones that are
(supposedly) for credit cards, which also use CRC to catch keystroke
errors. Wait a minute! Here. Try this:
<http://groups.google.c om/group/comp.lang.basic .visual.misc/msg/15c6ceedfb29e45 3>

It's VB code for a 32-bit CRC, but it should work.

Oh, hey! Here's a link to some LZH code as well:
<http://groups.google.c om/group/comp.lang.basic .visual.misc/msg/c87f2a42f7c521c a>

Again, VB code, but it should import ok. Wow, 1998. I should of
searched my newsgroup archives earlier.... <Sigh>

---
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[The Frog]

Chuck you magnificent creature! That LZH stuff will work wonders. What
a great link. I was in the process of learning all about the different
possibilities for compression with different algorithms and lots of
stuff about information theory and data entropy etc.... but this
simplifies the process considerably. Seeing a practical example in VB
is a real boon. Great stuff.

The reason for the error correction code is due to the need to
transmit the data and give some level of certainty that the data can
be accurately reconstructed if it is received. Reed Solomon will be
perfect for one part of this, and CRC for another. In short I am
developing a transmission process for an app / concept I am working
on.

It basically goes like this:
1/ Dont trust the IT department and assume everything is non reliable
outside the application itself

2/ Code all necessary functions into the application itself.

3/ Application should be capable of adapting the content of itself
(within a certain framework) so that new forms, data, reports,
functions, etc can be reliably imported and / or replaced.

4/ All data in the application should follow (relatively) secure data
handling practices so that information not destined for a certain set
of eyes doesnt get seen.

5/ The application should be capable of operating completely
remotely / stand-alone so that disconnected employees can still be
kept up to date

6/ Transmission of 'updates' needs to be done in discrete 'parcels' so
that the latest versions of things can be sent when needed and not the
entire application.

7/ Transmission needs to be reliable, deliverable and secure. (Error
Correction (FEC), Compressed (eg. Deflate), Encrypted (Combination AES
and Public / Private)

8/ The application has to be able to send a 'request' or 'report' to
the 'master' so that component version control can be done.

9/ The application has to be able to work in an integrated fashion
with the users email application if possible - or else update /
control can be manually done.

10/ The application should be based in standard MS Office components,
in this case Access (97).

Why go to all this effort? Simple: My company works in the
technological stone age and the acquisition of budget to approach any
development in a more serious way simply wont be forthcoming (at least
as far as my boss and I can see). If you let accountants run a
business you no longer have a business, you just have accounting -
investing in infrastructure must therefore have benefits that the
accountants agree with and the ones here, regardless of the financial
and workload (productivity) arguments you put forward, are simply not
interested and are actively seeking to remove budget from all other
departments. So in short I am boned for money, but have the time, so
onward I will go......its better than nothing and I hope will actually
work quite well. Its a hell of a lot of work though.

After I get a chance to play with the code a bit for the LZH and
become familiar with it, I will try and expand it to handle unicode
and also maybe a binary version (or byte array version).

I have found some source code in C for the Reed Solomon coding (I love
the internet way back machine), and will play with that over the
christmas break on the bad weather days and see what I can come up
with.

In the end I am developing a process. I will post the outcome (code)
for that here, and some instructions for its use. It should be a
method of both preparing and receiving data that will be about as good
as it gets - how you transmit it would be up to you.

With all the help others have contributed here I do hope that it will
be found useful. Even if it is just for 'secure' backups of data in a
text type format.

The way I envision the 'method' to work is to first create the error
correction (Reed Solomon) output, then to compress it, then to encrypt
it, then to encrypt it (AES), then to encrypt the key with a public
key, and reverse the process (use the private key of course) to get it
back and know that it is as it should be.

Thankyou all for the help and guidance. Thankyou especially Chuck and
Stuart. I will post the finished code here sometime in the early new
year when I get back from holiday. I will use this thread.

Cheers and many many thanks

The Frog