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The Iava Homepage

Updated: April 5, 2000

Table of Contents

Copyright Notice
What is Iava?
What is the difference between Java and Iava?
What can Iava be used for?
Other scripting languages for the Java platform
Installation and Usage of Iava
Version and Change History
Known Limitations and Bugs
Acknowledgements
Iava Bibliography

To download Iava as a zipped file (less than 200k), use one of  the links below. In order to obtain the
source code (which is not contained in the downloadable files below), write a short email to me.
For the source code, please mind the license.

Download Iava 0.92
This version needs JDK 1.2 or higher.
The old "com.sun.java.swing" naming scheme is not supported anymore.

For commercial use read this.

Copyright Notice and Terms of Usage for Non-Commercial Purposes

The Iava source code and binaries are copyrighted 1998/1999/2000 by  Mathias Richter. Permission for the use of this
software and the source code is granted for non-commercial use exclusively  under the following terms:
  1. This software is provided "as is". Under no circumstances may the copyright holder and author of this

  2. software be held liable for any damages or losses resulting in the use of this software.
  3. This copyright notice must always be part of all copies or redistributions of this software (source code

  4. and binaries (ie. class files, jar files, etc.).
  5. I (Mathias Richter) as owner of the copyright am provided  with information about modifications, bugs,

  6. bug fixes and uses of this software (mathias@acm.org).

What is Iava?

Iava is an interpreter that implements a subset of the JavaTM programming language.
The philosophy of Iava is to provide a scripting language that integrates seamlessly with
compiled JavaTM applications and the JavaTM platform. The motivation for using the JavaTM
language syntax is to provide the possibility to migrate scripted code into compiled
code without having to rewrite it. Thus, features of an application can be imlemented as
scripts and after they have proven useful, they can be integrated into the compiled
code by copy-paste.
By using a subset of the JavaTM syntax and semantics, adding scripting to applications
does no longer force developers to maintain two different systems with two different
languages. The border between compiled code and scripted parts of an application
becomes (almost) invisible.
 

What is the difference between JavaTM and Iava?

There are no class declarations in Iava. This means you cannot define classes,
or anonymous classes in Iava scripts. Apart from this limitation, Iava provides the
full syntax and semantics of the JavaTM programming language. Iava scripts can declare
public or private methods. Public methods can be invoked by scriptable
objects, i.e. objects embedding the Iava interpreter. Private methods are only
accessible from within scripts (using this mechanism, fpr example ActionListeners can be
created and used from within scripts, refer to the API documentation of the Scriptable
interface for details).
 

What can Iava be used for?

There are lots of good reasons for integrating scripting into an application. In practice,
a lot of examples of scripted systems come to mind: The first to name is certainly the
UNIX system (closely followed by almost every serious operating system). Other
prominent examples are Emacs and for Macintosh programmers the text editor Alpha
(based on Tcl).  Here is just a short list of those motivations that spawned the Iava project:

Other scripting languages for the JavaTM platform

There are quite a few scripting languages that provide integration with the JavaTM platform. There
exists an excellent site which summarises existing languages for the Java virtual machine.
 

Installation and Usage of Iava

Iava needs JDk1.2 or higher (or the corresponding runtime environment).
Just plug the location of the file "iava.jar" into your classpath. The Iava interpreter can be invoked
on the command line by java Iava.Iava [-p] [-w | <sourcefile.iava>].
The option -p turns on profiling to the file ./profile.txt while the option -w brings on a simple
interpreter window with a few self-explanatory features. Invokation without a source file starts
the Iava command line (tab at the end of a line serves as a line continuation).
For integrating Iava with your application to make it scripted, please refer to the API documentation.
 

Version and Change history

Version 0.3 was the first version released (to a close circle of friends).

Changes from Version 0.3 to Version 0.4

1. Changed the IavaConsole from AWT to Swing 101 and thus eliminated text selection bug from
    java.awt.TextArea. Changes to the GUI of the IavaConsole include separate windows which allow
    the observation of declared symbols and methods.
2. Added IavaRuntime scoping policy (global scope, script scope).
3. Added listener infrastructure for method declaration/method call observation and symbol
    declaration observation.

Changes from Version 0.4 to Version 0.5

1. Exceptions and Errors which occurred as part of the execution of a scripted method
    called from compiled code are now accessible. The class IError has been made
    public for that purpose and provides a method for getting the original Error or Exception
    it wraps.
2. Fixed a bug in the interpretation of primary expressions: calls using "this" as a reference
    did not work properly in verson 0.4.
3. Fixed a number of minor bugs.

Changes from Version 0.5 to Version 0.6

1. Fixed a bug in the logical operators "&&" and "||".
2. The Iava interpreter used to output errors/exceptions directly to System.out/err. This
    was impractical, because embedding classes might want to be informed about errors
    in script execution. So now, the interpreter methods "interpret" and "interpretFile" throw
    IErrors (which are derived from Error and do not have to be caught by calling code)
    which the calling code is free to catch or ignore.
3. Took out the classes IavaListener and IavaTalker of the framework.
 

Changes from Version 0.6 to Version 0.7

This was a maintenance release. The exception handling was improved in the Iava interpreter.

Changes from Version 0.7 to Version 0.8

1. Fixed the bug with non-public constructors. Now, scripts can
    work with classes with non-public-constructors which were created by compiled classes
   (e.g. Enumerations). Thanks, Scott!
2. Added a IavaAccess class which allows classes embedding Iava to
    restrict scripts from using certain classes or packages. Thanks, Tim!
3. Fixed bug with for-statements without a variant.
4. Iava and IavaRuntime can now be subclassed. Changed protection of
    methods in these classes to 'protected' where desirable.
5. IavaRuntime objects can be instantiated with their own classloader now.
   Thanks again, Scott!
6. The naming scheme "com.sun.java.swing" is not supported anymore.
 

Changes from Version 0.8 to Version 0.9

1. Re-fixed the bug with non-public constructors. Now it *really* works ;-)
2. Added some performance treats (method lookup cache, ArrayList instead
    of Vectors, etc.). Iava should run much faster now...
3. Fixed some minor errors (thanks Tiest!).
 

Changes from Version 0.9 to Version 0.91

1. Fixed a bug with the runtime stack, which would overflow under certain conditions.
2. Extended the signature of the classes of IavaRuntime and Iava. Now, the IavaRuntime
    class provides an extended set of protected methods available for subclasses. Iava provides
    possibility to exchange the runtime object for an interpreter instance. Thanks, Scott!
 

Changes from Version 0.91 to Version 0.92

1. Fixed a bug in method caching which would prevent method invocations with null values for
    parameters to be executed correctly.

Known Limitations and Bugs

The following bugs are known to me:

Unfixed as of Version 0.91: Please send me bug reports!!

Unfixed as of Version 0.7

Unfixed as of Version 0.5

Unfixed as of Version 0.4

Unfixed as of Version 0.3

Acknowledgements

I would like to thank all Iava users for helpful hints, suggestions,
bugfixes and for the positive feedback that I have been receiving.
In particular, I would like to thank Scott Boding and Tim Wright. Scott provided really
useful bugfixes while Tim suggested the restriction of script access rights. Tiest from
HTSoft has really been helpful in finding some more bugs fixed as of 0.9

Iava Bibliography

If you want a copy of these, drop me an email.

M. W. Richter, "Iava - Yet Another Interpreter for Scripting the Java Platform",
accepted for publication in Software - Practice & Experience, February 2000, Wiley.

M. W. Richter, "A Framework for Workflow-oriented Scripting in Java Applications",
Proceedings of JIT '99, Springer, 1999.