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The Purpose of di_Library

   Di_Library is designed as a set of drop-in replacements for the basic
   xBase user input/output commands.  Such replacements are intended to
   allow for easy porting of existing xBase terminal-based applications to
   World Wide Web CGI applications.  In addition to close equivalents of
   xBase input/output commands, di_Library contains (or will contain) a
   collection of functions for HTML specific features, CGI control, and
   device manipulation.  The specific intended strength of di_Library is
   that it allows the use of identical functions for input/output from/to
   both the terminal and a web-browser.  Common source code, and even in
   many cases a common executable, can be used to interface whatever user
   input/output device is used to access common underlying business logic.
   In the future, di_Library might include access to more device types in
   addition to the screen and a web-browser.  The Norton Guide you are
   currently viewing contains the documentation for di_Library version 0.1
   (alpha).

   Di_Library is written entirely in Clipper 5.3.  Full source code
   accompanies each distribution of the library.  While I do not expect any
   difficulty in compiling and using di_Library for other xBase
   environments and compilers than Clipper 5.3, no warranty is made or
   expressed as to such compatibility.  In addition, no warranty is made or
   expressed as to the suitability or usability of di_Library for any
   purpose.

di_Library vs. other libraries

   Other libraries created to assist in creating xBase CGI server apps have
   a somewhat different focus than di_Library.  I know of two such products
   currently:  FiveWeb and Webtools.  Both of these libraries are directed
   at developers who wish to create new CGI applications in xBase.  They
   provide HTML-centric output functions to allow the use a web-browser as
   an interface to xBase applications.  Although di_Library can also be
   used for the creation of new CGI applications using familiar xBase
   structures, its strength lies in the retro-fitting or "dual-fitting" of
   legacy xBase applications.  Rather than design user input/output
   functions which are specific to HTML, di_Library creates functions
   closely matching the syntax of existing xBase commands, but with an
   underlying device-independence.  A di_Library developer wishing to put
   existing applications on to the Web needs not rewrite all the user
   interface actions from scratch, as with other libraries, but simply
   search for individual @SAY's, @GET's and so on, and replace them with
   syntactically similar di_Library functions.  After such replacement, the
   source code (and the executable!) retain the ability to function
   unchanged as terminal-based applications.  See the Examples sections, as
   well as the DEMO.EXE module for examples of how this can work.