Monday, November 27, 2017

Note on using the interactive Java applications in this blog

Java issues

In the years since I started this blog, security issues regarding Java applets and Java Webstart have led to severe restrictions on their use.  That means it might be difficult to get these applications running in your browser.  If you encounter difficulties here is some advice to solve them:

  1. If you don't have a recent version of Java installed on your computer, you can get the latest version here.
  2. For running applets, I recommend using the Mozilla Firefox browsers.  Chrome doesn't like applets at all. 
  3. Instead of trying to activate the Webstart links directly, copy the linked file (ends with ".jnlp")  onto your computer and attempt to run it there directly.
    1. On a Mac, you cannot double-click on the downloaded jnlp (webstart) files to run them.
    2.  Instead activate the right-click context menu.
    3.  Then select "Open with... -> Java Web Start.app" menu item.  Otherwise it complains that they are from an "unknown developer" and refuses to run them.
  4. In the Java Control Panel (accessible in System Preferences on a Mac and I-don't-know-where on Windows and Linux) you might need to make the following changes:
    1. Select the "Security" tab.
    2. Add the site "http://page.math.tu-berlin.de/" into the Exception Site List. 
    3. Add the site "https://page.math.tu-berlin.de/" into the Exception Site List. 
    4. Set the security level to "High" instead of "Very High" (the two choices that remain).
  5. When starting up the Webstart, it may complain that the Java version asked for in the .jnlp file (1.5+ or 1.6+) doesn't match the installed one (which is now 1.8.x).  Just click on the option to use the installed version.
  6. It may ask whether you are sure you want to run the application. These warnings may have various reasons. You will need to trust me that none of them represent any danger. Possible reasons include:
    1. Because the application developer is unknown.
    2. Because the certificate will expire soon.
    3. Because the application asks for all permissions when it runs on your computer.
  7. The loading process may take awhile, especially the first time.  Be patient.
  8. As a last resort try clearing out the Java cache. 
    1. Go to the Java Control Panel (see above).
    2. Select the "General" tab.
    3. Under "Temporary Internet Files" click on the "View..." button.
    4. Select "Resources" from the ComboBox menu.
    5. Select all resources (click in the list and then type ctrl-a), then select click on the big red X button at the upper left of the window.
Good luck.  I'll gratefully post any more specific directions you may have discovered for your configuration.


Webstart Directions

Once you do manage to get the webstarts working, you still may have to initialize them properly.  Each has a property file which controls how the initialization takes place, but this file cannot properly be opened by the webstart process, hence here are the manual instructions for getting the app properly configured:
  1. Select the menu item "Window->Left Slot" (only if it's not already selected).  This brings up the application-specific control panel, without which the application is quite crippled.
  2. Deselect the menu item "Window->Right Slot" (only if it's already selected).  This navigation panel is generally not needed for the casual user and takes up valuable real estate.
  3. Select the menu item "Camera->Zoom tool".  Now you can zoom in and out of the 3D window using by scrolling with the mouse (or the equivalent motion on a touch pad, etc.).

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