XpkMaster

Contents

• My personal home page
• general information
• distribution
• xpk supporting programs
• sub libraries
• why use xpk
• What the xpk system consists of
• File format and overriding
• Beta testing (for beta testers only!)

Description
XPK is an interfacing standard between application programs and packer libraries. Every XPK application program can pack data with any XPK packer.

Distributability
XPK is copyrighted, but freely distributable for non-commercial use. Some parts of XPK have a different legal status, ie. PD, GPL or shareware.

The author
Starting with version 3.10 I (Dirk St�cker) am the programmer of xpkmaster.library. I continue the work of Urban Dominik M�ller and Christian von Roques with their permission!

The distribution

• xpk_User.lha
  This is the main part of the xpk distribution. In this archive are all the files you really need.
• xpk_Crypt.lha
  This part of the xpk distribution consists of all the cryptographic libraries. It may be illegal to export these libraries from the USA, therefore they are in a seperate archive, which shouldn't be made internationally available from the USA. We do not yet know of any restrictions to the import or export of this archive from other countries.
• xpk_Develop.lha
  In this archive are all files, which are needed to create own xpk applications.
• xpk_Source.lha
  In this part of the xpk distribution are sources to a lot of xpk stuff.

Xpk supporting programs

• XpkArchive System: (2.0) [FILE] - [README]
  xpkarchive.library handles archive creation like LhA or Zoo.
  Author: Matthias Meixner (meixner@rbg.informatik.th-darmstadt.de)
• XFH: (1.40) [FILE] - [README]
  XFH-Handler is a DOS handler which uses xpkmaster.library to provide transparent access to compressed files in a given directory or partition. All compression/decompression is done automatically by the handler when files are read or written. Compression is optional and may be switched at any time, allowing for fine control over storage of data. The compression method may be changed at will. Decompression is always automatic, you don't have to care about which compressor was used to create the files.
  Author: Matthias Scheler (tron@lyssa.pb.owl.de)
• XPKatana: (1.2) [FILE] - [README]
  Full-featured GUI for XPK, allows (un)packing, features a complete ARexx port, supports batch jobs, etc... Also supports FileID.library for filetype identification, and xfdmaster.library for alien packer decrunching, making it possible to repack most alien packing formats into a regular XPK format.
  Author: Eric Sauvageau (sauvae00@libertel.montreal.qc.ca)
• XPK-KNIGHT: (1.05) [FILE] - [README]
  XPK-KNIGHT is a free configurable, easy graphic user interface for comfortable usage of most of the important functions whithin the xpkmaster.library and its correspondending XPK packers.
  Author: Alexander Grossberger (nobody@betei.franken.de)
• Xit: (1.0) [HOMEPAGE] - [FILE] - [README]
  Xit is a AppIcon/AppWindow programming for packing and unpacking data with xpk. It was made as a replacement for xDrop, but has some more features. The GUI is created using MUI. Author: Laurent Kemp� (lkempe@nucleus.fr [home], lkempe@assisi.fr [work])
• XpkCybPrefs: (1.0) [FILE] - [README]
  XpkCybPrefs is an alternative to XpkMasterPrefs. It provides a transparent "intelligent" packing, according to the filetype (by simply setting "USER" as xpk packer and configuring once for all, you get everything working). Some features: Size conditions, "Multipacking" (trying multiple packers on data, keeping the best or fastest-decrunching etc... one!!), report-window with full info, user-choice requester ETC ETC... (100% user-configurable) Author: Alexis Nasr (nasr@hol.fr)

sub libraries

• BLFH [FILE] - [README]
  An encryption library that uses the Blowfish algorithm by Bruce Schneider. Four working modes available (ECB, OFB, CFB, CBC).
  Author: Dirk Pauli (dpauli@aix520.informatik.uni-leipzig.de)

Motivation

• Many programs that should offer data compression (e.g. HD backup utilities) do not.
• Many programs that offer data compression use old, slow, inefficient or inappropriate algorithm.
• All programs that offer data compression offer just one algorithm, you are stuck with that one.
• Many good packers are not used by any application program and have no good user interface.
• The installation of most packers requires AmigaShell knowledge (putting LhA in the path so that Directory Opus can find it)
• The decompression of all files packed with existing packers requires knowledge about the packer used for compression.
• Many compression programs can not deal with files that are larger than available memory.
• The existing compression programs are either slow or have a low compression factor.
• There is no way to support upcoming hardware compression cards in already existing applications yet.
• For none of the current compression programs exists a real decompressing file handler that uses no dirty tricks to decompress files on the fly.

Overview

The xpk standard is to data compression what xpr is to file transmission. It consists of three layers:

• Level 2 - xpkarchive.library The application/xpk interface for archives
  Offers archiving functions like "add this file to that archive" or "show me the contents of that archive".
• Level 1 - xpkmaster.library The application/xpk interface for files
  Offers functions like "Compress this file to that chunk of memory using that algorithm". All combinations permitted: Mem to mem, file to file, mem to file, decompression and compression. Asynchronous packing possible. Very convenient tag based caller interface. Determines automatically out which sub library to use for decompression. Returns detailed error messages.
• Level 0 - xpk sub libraries The xpk/packer interface
  All level 0 libraries offer the same functions. They're very small. Typical calls are: "Tell me what you can", "Compress this chunk of memory to another chunk of memory", and "Decompress this chunk of memory to another chunk of memory". These libs are very limited, their functionality is expanded by xpkmaster.library. No one would want to talk to a sub library directly.

In addition, there is an optional standard xpk file format.

All parts of the xpk standard are implemented in shared libraries. There is one master library for archive level access, one master library for file level access, and one library for each compression algorithm.

Xpk File format:
Offers checksums, chunks (important when Seek()s on a compressed file become necessary) and automatic handling by the xpkmaster.library. This means that any new packer that can only pack mem to mem has its own file format immediately. And most important: The name of the packer library is contained in the file. Therefore, copying a new sub library to LIBS: is all you have to do to install a new packer (easily done in installation scripts); xpkmaster.library recognizes the new file type immediately. No changes to xpkmaster.library or the application programs necessary. In case the xpk file format is not used, the introduction of a new packer requires a change the xpkmaster.library.

Overriding:
It is planned, that libraries of a lower level can offer higher level functions. They should be able to override the automatic functionality expansion by the higher level library. xpkmaster.library, for example, enforces the use of the xpk standard file format. It should be possible to override this by a sub library. Therefore an new library interface will be created, the xex libraries.

If you have any comment, problems, suggestions or WWW addresses concerning XPK, mail me at stoecker@rcs.urz.tu-dresden.de.

This page is too on my home server. If you have problems try there again.

This page was times accessed since 30.01.97. Information about last update you can see in source of the HTML file.