Using the KGS Go Server on OS X 10.8 Mountain Lion

by Carson Reynolds

On my computer at least the “Play Go Now” link on KGS doesn’t work. The quick workaround is to click the CGoban3 link on KGS and then double click on the downloaded cgoban.jnlp file. This should prompt you to enable Web Start applications. If you click “Enable” then you should see the CGoban3 Main Window, which has a “Play on KGS” button and from there you can log in (or click Guest if you are just getting started).

However, this easy method doesn’t make a permanent application for later use. Below are some better instructions that will install CGoban3 in Applications. You’ll first need to start /Applications/Utilities/Terminal. Next you’ll have to allow Java Web Start applications. To turn it on you need to access the Java Preferences. So, first run the following command:

# Open Java Preferences
/Applications/Utilities/Java\ Preferences.app/Contents/MacOS/Java\ Preferences
# Make sure Enable applet plug-in and 
# Web Start applications is checked.
# Close the Java Preferences window.

After you’ve enabled Java Web Start you can next launch javaws from the Terminal with a link to the KGS Application. This will prompt you to save CGoban.app:

# Launch CGoban with Java Web Start
javaws http://files.gokgs.com/javaBin/cgoban.jnlp
# You may briefly see a Downloading application progress bar.
# A file dialog appears chose the folder /Applications.
# Click "Save" to put "CGoban 3.app" 
# into the Applications folder.

After you’ve saved the Application, CGoban will launch and show the main window. As with before you can log in or get started as a guest. Have fun.

The overly curious among you might wonder what would happen if you directly try to run javaws before enabling Web Start:

javaws http://files.gokgs.com/javaBin/cgoban.jnlp

The first time OS X will prompt you to enable Web Start and even if you click enable it will dump you back at the prompt with an error message stating:

No Java runtime present, requesting install.
Unable to locate a Java Runtime to invoke.

But the second time javaws will actually work as expected, since Web Start is now enabled. Incidentally, if you run into trouble it is also worth mentioning that you can reset the local Java cache and thereby delete old or broken copies of CGoban (among other things). To do this, first look under the Java Preferences > Network tab next click the “Delete Files…” button. Anyhow, I hope this helps other Go players on the Mac get KGS up and running to their satisfaction.

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