On Nov 30, 2009, at 8:31 PM, Darin Fisher wrote:
>
>
> On Mon, Nov 30, 2009 at 7:55 PM, Maciej Stachowiak <m...@apple.com> wrote:
>
> On Nov 30, 2009, at 6:16 PM, Drew Wilson wrote:
>
>> Following up, I think this highlights the distinct set of use cases that
>> shared workers and shared script address:
>>
>> SharedWorkers are a great platform for when you have a single database that
>> is shared across multiple instances of your web app, and you want to
>> coordinate updates to that database. I can imagine sharing a single
>> connection to the server, etc via SharedWorkers.
>>
>> SharedScripts are a good platform for when you want to share data/code (for
>> example, the immense body of Javascript used to implement the Gmail UI)
>> across multiple windows. I can't speak to whether passing a hidden iframe
>> between windows as was suggested in the other thread would address this use
>> case sufficiently.
>
> Would it be fair to say the goal for SharedScript is just to share code and
> data (to reduce memory use of multiple instances of GMail), and not network
> connections, timers, or other APIs based on async callbacks (assuming those
> either remain per-Window or are in the SharedWorker)? If so, then it would
> pretty much completely be handled by sharing of some arbitrary JavaScript
> object, possibly arranged by SharedWorker.
>
> Sharing an out-of-document HTMLIFrameElement would almost even account for
> timers and the like, except that currently in WebKit a frame's Window does
> not exist and its contents are not loaded if the frame is not rendered.
>
> XHRs also don't work after the frame has been unloaded.
I think my primary concern is that the use of _Shared_ or _Global_ in the name
implies behaviour similar to that of SharedWorker, which is not guaranteed,
likewise origin based object lifetime can trivially result in differences in
behaviour between browser (which when coupled with the naming issue) could
easily become a headache for developers.
It seems that what is really wanted is a Worker context that isn't actually a
separate thread, so avoiding the need for postMessage, and have it be
explicitly instantiated so as to avoid any browser-architecture derived
behavioural differences. eg.
var mySharedContext = new SharableScriptContext("script to load here?");
mySharedContext.onload = function() {
doStuff();
}
// or should it be
// mySharedContext.src = "script to load here?"
Later on:
function doSomethingCoolThatNeedsANewWindow() {
var win = window.open(...);
win.onload = function() {
win.functionThatTakesScriptContext(mySharedContext);
}
}
// Note handling the passing of the shared context is entirely developer
defined -- eg. the only spec behaviour is the 'new SharableScriptContext'
everything else is whatever the developers wants
// Note 2: I am truly awful at naming things so these names are mostly chosen
to clarify unambiguously-ish what i believe the goal is
The downside is that it requires manually passing the context to new windows,
the plus side is that it doesn't provide (or imply) behaviour that may be
('necessarily') different between UAs.
--Oliver
>
> -Darin
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