java_visualize: visualization for java
David Pritchard (daveagp@gmail.com), created May 2013

This is the frontend for a Java version of Philip Guo's Python visualizer.
Try it at: 
      http://cscircles.cemc.uwaterloo.ca/java_visualize/

Whereas the OPT repo contains both a frontend and backend, the setup
to make this work in Java consists of entirely replacing the backend,
and then tweaking the frontend only where needed.

What's inside this directory:
 -- index.html is a modified version of visualize.html 
 -- jv-frontend.js is a modified version of opt-frontend.js
 -- java_safe_maketrace.php connects the frontend to the backend
 -- example-code is a directory full of example Java files to visualize

To get the frontend to work, in this directory, you need to:
 -- replace ./OnlinePythonTutor with a symlink (or subrepo, etc)
    to the code at https://github.com/pgbovine/OnlinePythonTutor/
 -- replace ./CodeMirror3 with a symlink (or subrepo, etc)
    to the code at https://github.com/marijnh/CodeMirror

Note that in the entire frontend, only java_safe_maketrace.php is a file
written in a server-side language. Everything else we use is static,
although OnlinePythonTutor has some server-side files that this Java
version does not use.

For the backend to work the recommended way, you should do these
optional but highly recommended steps
 -- install CEMC safeexec on your system --  https://github.com/cemc/safeexec
 -- install java_jail on your system -- https://github.com/daveagp/java_jail 
 -- you have to be root to set these up
 -- you don't want these backend packages in a folder accessible by http

You will have to modify the file locations mentioned in java_safe_maketrace.php
to reflect the installation location of your java_jail and safeexec (or 
lack thereof if you are living dangerously).

====

The modified files (index.html, jv-frontend.js) retain the MIT license 
under which they were published in the OnlinePythonTutor repo. 

The other files (java_safe_maketrace.php, example-code/*) are released under 
the GNU Affero General Public License, versions 3 or later. See LICENSE
or visit: http://www.gnu.org/licenses/agpl.html