java_visualize

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java_visualize: visualization for java David Pritchard ([email protected]), created May 2013

This is the frontend for a Java visualizer. It is based on "Online Python Tutor", a Python visualizer by Philip Guo. Try it at these mirrors (as of time of writing):

  http://cscircles.cemc.uwaterloo.ca/java_visualize/ (Java 8)
  http://www.cs.princeton.edu/~cos126/java_visualize/ (Java 7)

The Online Python Tutor repo contains both a frontend and backend. For Java wre readapt the frontend (so this repo contains OnlinePythonTutor as a subrepo) and replace the backend (it is in the java_jail repo mentioned below, since it runs in a sandbox).

INSTALLATION

Install these on your server first: https://github.com/cemc/safeexec https://github.com/daveagp/java_jail This requires root access. See the instructions therein for details. It is best to install these in locations that are not served to users by your web server.

Next, in some folder accessible to your web server, run

git clone --recursive https://github.com/daveagp/java_visualize

It's recursive because it includes two submodules. Because of this, to update, use the pair of commands git pull; git submodule update

At this point, visiting http://your.website/url/to/java_visualize/ should give you a beautiful (but non-working) frontend, and http://your.website/url/to/java_visualize/java_safe_ram_maketrace.php should give you a "Couldn't find jv-config.json" error.

Next, copy jv-config.example.json to jv-config.json. Now visiting http://your.website/url/to/java_visualize/java_safe_ram_maketrace.php should give you a "http mangling" error.

Finally, edit jv-config.json to indicate where you installed safeexec and java_jail. (Just those first two entries need to be changed right now.)

Now, try the visualizer out!

THE "C++ VISUALIZER" See cpp_visualizer.txt.

FAQ -- click on "Click for FAQ" on the visualizer page

MORE INFO -- index.html is a modified version of visualize.html -- jv-frontend.js is a modified version of opt-frontend.js -- java_safe_ram_maketrace.php connects the frontend to the backend -- config.* is used for configuration stuff specific to your server -- pytutor-customizations.{js,css} overrides some behaviour of OPT -- example-code is a directory full of example Java files to visualize

Note that in the entire frontend, only the two .php files are 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.

If you use a database, you'll be putting a DB password in jv-config.json. Please check that http://your.website/url/to/java_visualize/jv-config.json is inaccessible; .htaccess tries to do this, but you should confirm it works.

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

The other files are released under the GNU Affero General Public License, versions 3 or later. See LICENSE or visit: http://www.gnu.org/licenses/agpl.html