Re: java callbackks

From: Matthias Berth <>
Date: Wed, 21 Dec 2005 11:04:33 +0100


if everything else fails, you can still run a tiny http server on the
java side and have javascript poll that for incoming messages :-). Just
my $0.02


Andrew Harrison schrieb:
> David,
> Thanks for your prompt response!
> My extension aims at making Firefox a peer in a P2P sense. So I need to
> get arbitrary messages received by the back-end Java peer into Firefox.
> This will be queries for resources/uris (I've mentioned this before -
> PiggyBank data) received from the P2P network, but a simple chat window
> is my current proof-of-concept. So I don't know when the messages will
> arrive. I'm just wondering if I can cobble something together with JNI
> but that's going to be messy because currently I get Java using your
> sly technique from JS, but JNI needs to go (in my experience) via the
> Java plug-in. Not quite sure how these different access methods to the
> JVM would affect things...hmmm
> cheers,
> Andrew
> On 20 Dec 2005, at 20:54, David Huynh wrote:
>> Andrew,
>> Unfortunately I think you're trying the impossible, at least at the
>> moment, because I have tried for the same thing and failed twice
>> before (on Windows). Perhaps with more native support for Java in
>> Firefox, we can hope to have callbacks.
>> If you can tell me more specifically why you need the Java backend to
>> send messages back to the frontend, perhaps I can suggest a user
>> interface solution that does not require the callback.
>> David
>> Andrew Harrison wrote:
>>> Hi,
>>> I apologise in advance for sending this message to this list because
>>> it's not a PiggyBank question. But there are few places that have as
>>> much expertise with Firefox and Java. And I'm stuck...
>>> So I'm trying to add a JS Object that is invoked from XUL as a
>>> listener to a back-end Java class, in order for the Java class to
>>> send messages into Firefox. The Java class has a method:
>>> void addJSListener(JSObject jsobject);
>>> The JS Object calls on the Javascript-Java 'bridge' component in the
>>> extension to invoke this Java method, giving itself as a parameter
>>> ('this'). But when the component arrives in Java it's null - the
>>> JSObject.toString() returns 'null'. If I try and print the JSObject
>>> parameter I get a null pointer exception. If I invoke a method on
>>> the JSObject like eval or call I don't get an exception, but nothing
>>> happens, which is frustrating.
>>> Most of the documentation I can find on JSObject presumes the Java
>>> side object is an Applet, which mine isn't.
>>> So the question is, am I trying to do the impossible (i.e. use
>>> JSObject not from an Applet)? Also I'm using a Mac (with Firefox
>>> 1.5)- could this be an issue? Or am I just missing something stupid?
>>> Optimistically thanks in advance,
>>> Andrew
Received on Wed Dec 21 2005 - 09:57:40 EST

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