Re: VisAD Applets not redrawing after returning to page.

• To: visad-list@xxxxxxxxxxxxx, "David Nguyen" <dave@xxxxxxxxxxxxxx>
• Subject: Re: VisAD Applets not redrawing after returning to page.
• From: Curtis Rueden <curtis@xxxxxxxxxxxxx>
• Date: Mon, 04 Mar 2002 13:03:15 -0600

Hi David,

This is a known issue with VisAD applets.  Unfortunately, I do not
know of any workarounds for the problem.  You can use Javascript to
instruct the browser to open the applet in a separate browser window,
but the problem will still occur if the user closes that window and
reopens it later.

As I said in a previous email to the list:
   http://www.unidata.ucar.edu/cgi-bin/mfs/89/2860

>Unfortunately, I have not found a solution to this problem. I noticed
>the following things while experimenting:
>
>1) If you go to the Java Plug-in Console in IE, and press 'X' to clear
>   the class loader cache, then reload the applet, it works again.
>
>2) If you refresh the applet web page a few times, after a few tries
>   it will display properly again.
>
>Based on the above, my guess is that the problem stems from the Java
>Plug-in class loader, although I have no idea if any work-arounds are
>possible.

So, there is something strange about the interaction between the Java
Plug-in's class loader and VisAD that's causing the behavior.

-Curtis

At 11:41 PM 3/3/2002, you wrote:
>Hi All,
>
>I am having some trouble with using VisAD in applets. It seems to work
>fine when I first load the application, but if I visit another page and
>return later (via the back button) the visualization does not return.
>The VisAD display component, however, is there.
>
>I have posted a small demonstration on my website. It is a slightly
>modified version of Ugo Taddei's first program in his tutorial. I have
>modified it slightly so that it will run as an applet. When you first
>visit the page, it works fine. Then if you visit another page, say
>www.yahoo.com, hit the back button, the display does not work the second
>time.
>
>The applet can be accessed at www.davenguyen.net/3dscivis/visadapplet. I
>have also attached a copy of the modified code.
>
>I am not sure if this is a java issue: am I not completing something
>properly, or if this may have something to do with VisAD. Can someone
>point me in the right direction?
>
>Thanks in advance,
>
>--------------------
>David Nguyen
>Computer Engineering
>Northwestern University
>dave@xxxxxxxxxxxxxx

• References:
  • VisAD Applets not redrawing after returning to page.
    • From: David Nguyen