GRIDL README
=============
19 July 2000 hsh@cs.umd.edu


This readme file provides an overview of the GRIDL package, in its
current form as of 19 July 2000. The descriptions found within this
file are based on my informal read-throughs of the code. As I was not
the original author of any of GRIDL, my comments are based on reading
the code and do not account for any experience gained during the
initial design. In other words, please take everything that is said
here with a grain of salt.

This version of GRIDL is somewhat "cleaner" than earlier versions - we 
have eliminated the dependencies on some external libraries,
re-organized the packages, and renamed the code hierarchy to conform
to Java standards (package "edu.umd.cs.gridl.*").

However, there is still a good deal of code that may be cryptic,
obscure, bizarre, or simply unused. A more extensive revision of GRIDL 
is under consideration: a rewrite would hopefully address some of
these problems. 

It is assumed that the reader is sufficiently comfortable with Java to 
set classpaths appropriately. Basic makefiles are provided to help
with compiling.

Files:
------

This package contains the code for GRIDL, under the edu/umd/cs/
hierarchy. An example data files is given in demo.txt, and the html
file in the top-level of the package can be used to invoke the 
applet. 

Packages
---------

GRIDL has 6 packages:
        
        controller: contains the main Applet code and an additional
                class used to start things going.
        
        database: code for AVLTree data structures and supporting
                classes.

        model:  Code for reading data model from text file, one line
                at a time, and creating resources.
                
        hieraxis:  Creation and management of the Hieraxis, along with 
                related support classes.
                
        ui:     Management of the main interface, includinge the GRID
                of points   
        
        util: Utility code, including a HashSet and a GraphLayout.

Most of these packages contain their own README files which provide
in-depth description of the classes involved. A general design README
can be found in /edu/umd/cs/gridl, containing a description of some of 
the control flow of the program.

The images under /edu/umd/cs/gridl contains GIF files that are used in 
various places in the code.
        
Data Structures
---------------

The current version of GRIDL assumes that all data is stored in a
single flat file, with fields separated by whitespace. The first line
of the file contains the names of the fields, with the type of each
field given in the second line. Each subsequent line contains a single 
record.

To Be Done
----------

- clean up code and redesign where appropriate.

- Replace flat file and AVL tree model - with entire database read
into memory at start-up - with a generic data model that could be
implemented through subclasses providing hooks to SQL, XML, etc.

- Fix text handling on labels of Hieraxis. Improve performance and
space utilization.