Re: java callbackks

From: Andrew Harrison <>
Date: Wed, 21 Dec 2005 11:05:24 +0000

Hi Matthias,

I know, but I *really* want to avoid that.



On 21 Dec 2005, at 10:04, Matthias Berth wrote:

> Hi,
> 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
> Matthias
> 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 - 10:58:09 EST

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