Re: Asynchronous i/o, Garbage Collection, Funtion Instance references

From:
=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>
Newsgroups:
comp.lang.java.programmer,comp.lang.javascript
Date:
Sun, 15 Mar 2009 21:21:02 -0400
Message-ID:
<49bda97a$0$90270$14726298@news.sunsite.dk>
Richard Maher wrote:

c) I don't want to lock up the browser EDT while I'm waiting for a Read to
complete and have previously used a single-thread and the Socket Timeout
method as a sort of delayed poll which let user events/clicks through every
"n" seconds. What I want to do this time is use the separate thread to
invoke JSObject.call() for each message received. No problem with using a
static JavaScript function (I've done so successfully with async UDP
messages) but, as there may be many messages received per message sent and
there is no restriction on additional messages/requests (or message types)
being sent before all messages/responses for a prior message have been read,
I was hoping to use closures and anonymous function instances to preserve
and pass message-specific parameters to asynchronous read-completion
routine/callback.

d) The good news is the requests will be on a single connection-oriented
Socket and will be processed on a FIFO basis, so storing parameter objects
in an JavaScript/Java Array certainly seems doable. (I'd pass a serial
number with the outgoing message and check it against what we're expecting
to read next and use push() and shift() to manage the Array)

e) I have to admit to being a bit bamboozled as to whether Java has received
the function instance by reference, and once the JS function's local
variable that passed the reference to Java has RETURNed (or that local
variable re-assigned) and nobody on the JavaScript side is left referencing
that instance of the function, that the garbage-collector might clean-up the
function even though my Applet would be expecting to call it some time in
the future.

f) Even if longevity was assured, stuffed if I know of a method that would
deserialize the function (or function reference) so that it could accompany
the outgoing message to the remote 3GL routine and come back in a reply and
be serialized into a useful form. As a procedural guy at heart, to me it
looks like a great case for malloc, pointer, free but hopefully someone can
show me the optimal OO way of achieving this.


As suggested in previous reply. Just send a string with the
function name and use eval in the response processing JS.

JS->Java->JS or JS->Java->server->Java->JS should not matter.

Arne

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