Installing Jess

Jess is available in both the Linux Lab (in /usr/apps/Jess71p2) and the Windows Lab (in c:\program files\jess71p2). It is also available through Eclipse in the windows lab (linux lab coming soon).

These instructions are for installing it on your own computer.

Installation

First, you will need an up to date installation of Java. You may already have java installed. Try running the command java -version from a command prompt. As of this writing, the latest version is 1.6.0_23, but you don't necessarily need the latest version. If you don't have any version, you can download the latest JDK from http://www.oracle.com/technetwork/java/javase/downloads/index.html. Make sure to get the JDK, not the JRE.

Next, download Jess 7.1p2. (You must be logged in to download this file.) Extract the contents of the zip file to somewhere you'll be able to find it again later, such as /usr/local/jess71p2 or ~/jess71p2 on Linux or OS X, or c:\program files\jess71p2 on Windows.

If you use the Eclipse IDE, you can install the Jess Developer's Environment at this time. To install the JessDE, simply exit Eclipse, unzip all the files from Jess71p2/eclipse/ into the top-level Eclipse installation directory. Confirm that a directory named plugins/gov.sandia.jess_7.1.0 exists under your Eclipse installation directory, and then restart Eclipse.

Environment Variables

In order to function properly, Jess requires some environment variables to be set properly: PATH, JAVA_HOME, and JESS_HOME.

PATH should contain the full path to the java executable (as well as any other paths for software you've installed in nonstandard locations). If you want to run Jess from any directory other than the one in which it's installed, the path to Jess's bin directory should be in here also. In Windows, multiple paths should be separated by a semicolon (;). In OS X and Linux, they should be separated by a colon (:).

JAVA_HOME should contain the full path to the JDK's top level – something like /usr/java/latest, c:\program files\java\jdk1.6.0_23, or /Library/Java/Home.

JESS_HOME should contain the full path to your Jess installation – /usr/local/jess71p2 or c:\program\files\jess71p2, for example.

For Windows and Linux, PATH should probably contain both JAVA_HOME and JESS_HOME, with /bin appended to each. For OS X, java should already be in the PATH, so you should just need to add the path to Jess.

Here's how to set those:

Windows XP

  1. Start → Control Panel → System → Advanced
  2. Click on Environment Variables, under System Variables, find PATH, and click on it.
  3. In the Edit window, modify PATH by adding the desired path(s) to the value for PATH. If you do not have the item PATH, you may select to add a new variable and add PATH as the name and the desired path (c:\program files\java\jdk1.6.0_23\bin;c:\program files\jess71p2\bin) as the value.
  4. Close the window.
  5. Open a new command prompt and see if the commands java -version or jess work.

Windows Vista/7

  1. Right click “My Computer” icon
  2. Choose “Properties” from context menu
  3. Click “Advanced” tab (“Advanced system settings” link in Vista)
  4. In the Edit window, modify PATH by adding the desired path(s) to the value for PATH. If you do not have the item PATH, you may select to add a new variable and add PATH as the name and the desired path (c:\program files\java\jdk1.6.0_23\bin;c:\program files\jess71p2\bin) as the value.
  5. Close the window.
  6. Open a new command prompt and see if the commands java -version or jess work.

Linux / OS X

  1. If the commands java -version and jess work, then the PATH is already set correctly.
  2. If the path is not already set correctly, edit the file ~/.bashrc in your favorite text editor.
  3. Add these lines to the bottom of the file:
    JAVA_HOME=/usr/java/latest
    JESS_HOME=/usr/local/jess71p2
    PATH=${JAVA_HOME}/bin:${JESS_HOME}/bin:${PATH}
    export JAVA_HOME JESS_HOME PATH

    Make sure to use the actual paths you installed into, if the ones above are not correct.

  4. Save the file and log out, then back in.
  5. See if the commands from the first step work now.

Testing

See the Jess documentation for more details.

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