How to decode LZ1 attachments

Hi,

I currently have a problem with exporting messages with attachments to DXL via the C API.

When the attachments are encoded with Huffman encoding, the DXL export functions automatically decode them so everything is fine. But when the attachments are LZ1-encoded, they remain in encoded form in the DXL.

Is there a way of either:

  1. Decoding the attachment after exporting it to DXL?

  2. Getting the DXL exporter to decode the attachment (the ideal solution)?

I understand that saving to disk will decode any attachments but this is not an option for me.

Any suggestions greatly appreciated.

Regards,

David

Subject: RE: How to decode LZ1 attachments

Sorry, LZ1 attachments are never decoded during export. There’s an NotesDXLExporter property to do this coming in version 8.

I’m not certain, but I believe this is the same LZ1 that you can read published algorithms for online, so you can probably write your own decoder.

Subject: RE: How to decode LZ1 attachments

Hi,

if you want to fall asleep :slight_smile:

http://www.research.ibm.com/journal/rd/426/craft.html

Old stuff that i have in my mail archive…

and tonight I’M falling asleep writing a procedure about the Daylight saving time…zzzzzzzz

JYR

Subject: RE: How to decode LZ1 attachments

ok, thanks for the input guys, will have to mull it over :slight_smile:

regards,

david

Subject: How to decode LZ1 attachments

Hey, I got the same problem with you, have you got any clue on decoding the lz1 encoded attachments?

Thank you!

Subject: RE: How to decode LZ1 attachments

A fast hardware data compression algorithm and some algorithmic extensionshttp://researchweb.watson.ibm.com/journal/rd/426/craft.html

This paper reports on work at IBM’s Austin and Burlington laboratories concerning fast hardware implementations of general-purpose lossless data compression algorithms, particularly for use in enhancing the data capacity of computer storage devices or systems, and transmission data rates for networking or telecommunications channels. The distinctions between lossy and lossless compression and static and adaptive compression techniques are first reviewed. Then, two main classes of adaptive Lempel-Ziv algorithm, now known as LZ1 and LZ2, are introduced. An outline of early work comparing these two types of algorithm is presented, together with some fundamental distinctions which led to the choice and development of an IBM variant of the LZ1 algorithm, ALDC, and its implementation in hardware. The encoding format for ALDC is presented, together with details of IBM’s current fast hardware CMOS compression engine designs, based on use of a content-addressable memory (CAM) array. Overall compression results are compared for ALDC and a number of other algorithms, using the CALGARY data compression benchmark file corpus. More recently, work using small hardware preprocessors to enhance the compression of ALDC on other types of data has shown promising results. Two such algorithmic extensions, BLDC and cLDC, are presented, with the results obtained on important data types for which significant improvement over ALDC alone is achieved.

JYR

Subject: thank you for your help.

It seems that there are some parameters can be tuned in the lz1 algorithm, so … still hard to decode the data.

It seems that someone has made it several years ago, I dig out a post:

http://www-10.lotus.com/ldd/nd6forum.nsf/ShowMyTopicsAllFlatweb/432a51ccf793f61b8525701a00408703?OpenDocument