#
# FILE .../CPAN/hp200lx-db/README
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# $VERSION= '0.09';
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# written:       1998-01-10
# latest update: 2000-01-02 22:06:11
# $Id: $
#

Purpose:

  DB.pm implements the perl package HP200LX::DB which is intended
  to provide a perl 5 interface for files in the generic database
  format of the HP 200LX palmtop computer.  The perl modules are
  intended to be used on a work station such as a Unix machine or
  a PC to read and write data records from and to a database file.

Goals and Non-Goals of this Project:

  The primary goal was to read and write complete generic database
  files, e.g. GDB, PDB or NDB files on a host computer.  The
  transfer from and to the palmtop computer, synchronization and
  reconciliation were not considered at all yet.  Also, other
  built-in applications operate on slightly different DB files,
  these are not dealt with yet.  The creation, definition and layout
  of new databases are not handled yet.

  Project Roadmap:
  1. read/write GDB, PDB, and NDB files [quite complete]
  2. a simple GUI to browse the DB files [in progress]
  3. tools to import/export data in different formats [in progress]
  4. extend the DB module for ADB and WDB files [in progress]
  5. creation of DB files including format definitions etc.
  6. dealing with encrypted DB files [in progress]

Status:

  The package and any other files are in a completely EXPERIMENTAL
  STATUS and should not be used without proper backup.  Use it at your
  own risk, no support can be provided but bug reports and suggestions
  by e-mail are welcome.  Please read the notes below first.

  Note: The package emits all sorts of diagnostic information, these
        are not errors and change from release to release, depending
        on the development progress.

  Note: The DB formats have a number of limitations, this package
        tries to enforce them but most are not dealt with properly yet.

  Note: reading ADB files is fairly complete, an extension which
        can also write and update ADB files is currently in development.

Installation:

  The usual installation strategy

    perl Makefile.PL
    make
    make test
    make install

  should produce viable modules.

  Note: Under 4Dos do not run dmake.  "command /c dmake" should work.

Limitations:

  Development has been driven by my own requirements and my needs
  are not so big, so you should not be surprised if much remains left
  to be done.  Here is a list of missing things that I'm aware of:

  + Databases can only be read or updated.  It's not possible to
    create a database from scratch.
  + Only GDB, PDB and NDB files are covered, the more special formats
    ADB and WDB need a few more hacks.  As of now, these files can
    be read but not written!
  + When storing records to the database, make sure that fieldnames
    match exactly, including blanks, case, and national characters.
  + Lines in note fields should be stored with \r\n line endings.
    This is not checked here.
  + The viewpoint table is not rebuilt by default when a database is
    updated.  This must be done explicitly on the HP 200LX after loading
    the database by starting the "SORT" dialog.
    Resorting a view point is usually done by pressing F7 and F10.
    The DB also supports a method to update view points:
      $db->refresh_viewpt (-1);
  + Databases with password protection are not handled yet correctly,
    it is however possible to read the password using the
      $db->recover_password ();
    method!

    If you didn't already know, the password protection is not
    very secure in the HP-LX!
  + Be also aware of Perl's limited TIEARRAY implementation.
    Array elements need to be accessed by index.  No push, pop,
    shift and unshift operators are available.

Examples:

  The directory "demo" contains a few code fragments, working scripts
  can be found in the "scripts" directory:
    catadb.pl           export the contents of an ADB file in various formats
    catgdb.pl           export the contents of GDB, PDB, NDB and WDB files
    txt2ndb.pl          import text paragraphs into a NDB file
    xdb.pl              Perl/Tk GUI for DB files
    leer.ndb            empty german NDB file used for txt2ndb.pl

Availability and Contact:

  This package is available from my FTP archives

    ftp://ftp.wu-wien.ac.at/pub/usr/edvz/gonter/hp200lx/
    http://falbala.wu-wien.ac.at:8684/pub/english.cgi/0/24065

  and I can be reached as Gerhard.Gonter@wu-wien.ac.at
  or g.gonter@ieee.org .
  Redistribution is permitted but it must include the README file.

Copyright:

  Copyright (c) 1998 Gerhard Gonter.  All rights reserved.
  This is free software; you can redistribute it and or modify
  it under the same terms as Perl itself.

-----------------------------------------------------------------------------

interface functions
  $db= HP200LX::DB::openDB ($fnm)     read database and return an DB object
  $db= HP200LX::DB::new ($fnm)        create database and return an DB object
  $db->saveDB ($fnm)                  save DB object as a (new) file

array tie implementation to access database data records
  tie (@dbd, HP200LX::DB, $db);       access database data in array form
  TIEARRAY                            stub to get an tie for the database
  FETCH                               retrieve a record
  STORE                               store a record
  $db->get_last_index ()              return highest index

Notes:
All database data are read from file or written back in one burst.
No attempt has been made to read data when it is accessed by the
perl application.  This only complicates matters and does not seem
to be necessary since a type HP 200LX only has about 4 MB to store.
