This is an R package that allows users to create Java objects, invoke
their methods and execute Omegahat expressions from the R language.
This uses the embedded Omegahat interpreter to provide the Java
access.
Installation:
============
To install this R package, you can execute the command
R INSTALL Java_0.51.tar.gz
or
R INSTALL Java
The configure script attempts to locate the necessary tools,
libraries, etc. on your system. It finds the Java installation
in the following way.
a) if you set the environment variable JAVA_HOME, it uses this
to locate the java executable as ${JAVA_HOME}/bin/java,
or
b) if searches through the shell's path to find java and takes
the first one.
This requires Java 1.2, and also works for Java 1.3. Currently, this is
known to work for the
a) JDK 1.2 and 1.3 from Blackdown for Linux (http://www.blackdown.org),
b) JDK 1.2 and 1.3 from Sun for Solaris (SunOS 5.6 and 5.7).
c) JDK 1.3 from IBM for Linux (http://www.ibm.com/java/jdk)
In the near future, we will attempt to support this on Windows.
These are the only JDK implementations we have tried at this point.
Please let us know if you have success or problems with other implementations and
other platforms. Send mail to omega-devel@www.omegahat.org.
We have encountered problems (i.e. crashes) under Blackdown's JDK1.2
for Linux when the graphics thread is created (i.e. when we create a
GUI). This does not appear to happen under Solaris (JDK 1.3) or with
the IBM JDK 1.3.
Check:
=====
The R CMD check is conceptually at odds with an inter-system
interface such as this. First of all, one has to configure
and initialize the JVM before running any of the examples.
Secondly, the Java classpath for the examples may be different
than for regular use. And finally, some of the examples are
interactive in the form a GUI and will not return control
until the user clicks on a button.
Thus, don't run R CMD check (unless you have the appropriate
startup file that initializes the JVM approriately.)
Documentation:
=============
The documentation for this package is very much a work in progress.
There are help files for each of the functions.
There is also a collection of documents that are installed in the
Docs/ directory of the package. As the documentation evolves,
updates will be available from
http://www.omegahat.org/RSJava
Example R scripts are installed in the examples/ directory.
Bugs:
=====
Please report bugs to the omega-bugs@www.omegahat.org
list or use the Web-based bug reporting form at
http://www.omegahat.org/omegahat-bugs
Future plans:
============
The underlying Omegahat mechanism has a smart mechanism for allowing R
functions and closures to implement Java interface classes. It does
this by dynamically compiling and loading Java classes that make
callbacks to the R engine. As more people use this package and the
need for conversion are understood, this automatic conversion
mechanism will be activated.