Re: inter-applet communication problems

From:

Eric Capps <no@thanks.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 06 Aug 2006 12:26:49 -0500

Message-ID:

<eb58ou$o8d$1@geraldo.cc.utexas.edu>

I've rearranged your reply a bit for clarity.

Andrew Thompson wrote:
>> ...It is possible to call those
>> JavaScript commands from a second applet in the same page
>
> Wait a second. Lets make sure we're all
> of the same understanding here.
>
> While there are a number of ways to load a second
> applet, there is only one applet element in that HTML.

Ahhhhhh, okay. In the source of the test page you see one applet tag,
referencing the JmolControl applet (my applet). You also see a series of
JavaScript commands. The jmolApplet(300) command results eventually in a
function call that, among other things, writes the second applet tag to
the page. So, at the time you click the "test" button, there are
actually two applets in the HTML.

The bottom line: it is possible to call methods in the Jmol applet from
JavaScript (the Jmol-new.js file).

It would be nice to see an URL where I can confirm
that for myself..

The jmol-new.js contains several such methods. I believe this is also
just a standard ability of JavaScript. For my JmolControl applet for
example, you can see that the "test" function has the attribute
onclick="document.JmolControl.testMethod()", which I believe is
essentially a JavaScript call to a Java method. There's a bit on that
here:
http://java.sun.com/j2se/1.5.0/docs/guide/plugin/developer_guide/js_java.html

But since you're the one helping me, I'm going to guess you already knew
that. As for Jmol in particular, consider the following piece of code
from Jmol-new.js:

function jmolReplaceAtomCoords(coords, targetSuffix){
   _jmolCheckBrowser();
   var applet=_jmolGetApplet(targetSuffix);
   if (applet)
     applet.getProperty('jmolViewer').replaceAtomCoords(coords);
}

This calls the getProperty(String) method of the JmolApplet class (which
returns internal Jmol classes that you can then call the methods of).

....(what I have
been doing!)

Without the 'working example', and without a clear
understanding of what you are trying to do (as
we determined earlier), it is still tricky for me to know
what should happen in your example, or what it
looks like when it fails (note that when I first visited the
page, there was no model onscreen - then I clicked
the link to the source file, and when I returned - 'hey
presto' ..the model appeared)

That was due to poor coding on my part. I have changed the test page,
the model should now load when the visible applet (Jmol) does, and I
have removed the "got window" alert, as that should never be a problem..
What should happen: Jmol and the model loads. Click test. The method
testMethod() of JmolControl.java is called. The following alerts occur,
in order:

test method called
got applet
applet is of type: JmolApplet (any other type is a problem)
applet is instance of JmolApplet, attempting typecast
succesfully typecast

For me, this always stops before the "succesfully typecast" alert. The
error occurs during typecasting, on this line in JmolControl.java:

JmolApplet ja = (JmolApplet)a;

...So, shouldn't it be possible to bypass the JavaScript
altogether and call methods from the Jmol applet from the second applet?

I need to become clear on this 'second applet' yet.

Can you set up a test with HTML that includes both applets?

Again, both applets make it to the page. My applet, JmolControl, is the
<applet> tag you can see in the HTML. The Jmol applet tag is written via
javascript.

I don't think the Jmol-new.js has much to do with this, but if you like
I can highlight parts of it that may be significant and upload them on
that test page.

This email is very long!

Important note - this is not email, it is a post to a usenet
newsgroup. Email generally
- does not get archived by news servers,
- is not publicly searchable
- does not contribute to the bandwidth of subscribers to this group ;)

..and that makes me aware that we are still x-posting
this to both c.l.j.p. and c.l.j.h. I have set follow-ups to
c.l.j.programmer only.

Noted! I realize this may seem like a giant problem, but what I am
trying to do is really quite simple (I'm amazed I've been having this
much trouble with it) if you can look past the mountains of JavaScript
and get to the important parts, something I will help you do as much as
possible.

-Eric

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