[webkit-dev] GlobalScript API.

Dmitry Titov dimich at chromium.org
Tue Sep 1 16:13:55 PDT 2009

Thanks a lot Maciej!
As a note to the API described in this thread: there was a proposal in
private thread to replace the JS constructor with 4 parameters with a tag:

instead of
var globalScript = new webkitGlobalScript(name, url, loadHandler,

to have this:
<webkit-globalscript name='...', src='url', onload=...

The first tag with a specific name that provides a src or inline script or
injected with innerText would effectively supply 'initial script'. The
later-encountered tags withthe same name would have their initial script
ignored and simply connected to the same one. The tag's DOM element would be
EventTarget (for load and error) and have a 'context' property to pull the
global scope object of the script.


On Mon, Aug 31, 2009 at 7:18 PM, Maciej Stachowiak <mjs at apple.com> wrote:

> On Aug 31, 2009, at 6:09 PM, Dmitry Titov wrote:
> Hi WebKit-dev,
> I'm hoping to get your advice on Global Script proposal and how to start
> implementing it as an 'experimental API' since it's not standardized yet.
> As part of work on Workers in WebKit and Chromium, we discussed them with
> our web application folks (mostly gmail). We came to the idea that in
> addition to workers, they need a shared script context which runs on the
> same UI thread and directly scriptable.
> Our previous take (with an invisible window running all the time in the
> background) was not that fruitful but it indicated the way to go. We are
> thankful to the members of the whatwg community for the detailed threat
> analysis of 'permanently running invisible pages', it helped very much. Not
> right away but it was absorbed :-) Current proposal reflects realization
> that there is a less-powerful way to achieve the same benefits.
> I'm looking for a way to implement it as an experimental API in WebKit and
> Chromium. I'm thinking it can go the similar way as webkitNotifications -
> surrounded by ENABLE(GLOBAL_SCRIPT) and prefixed with 'webkit' to keep the
> difference.
> Here's what I think we should take a look at:
> 1) Does this proposal have a potential standards-track future? Relevant
> specific issues would be interest from other browser vendors and standards
> folks, interest from content producers, and our own degree of confidence
> that this is the right approach. Note: in some cases a prototype can be the
> best way to address concerns, however. In some cases we're willing to add
> proprietary extensions that have little hope of ever becoming a standard,
> but almost always we do this for the sake of non-browser use.
> 2) Do we have some agreement in the WebKit community that this is a good
> approach? It would be good for us to do some of our own design review, if
> this isn't going to be a standard in the foreseeable future.
> If we are optimistic about the future, then an ENABLE macro and a WebKit
> prefix would be a good way to handle things.
> I will do some detailed design review soon.
> Regards,
> Maciej
> I'd appreciate much your advice on the whole API and on the way to bring it
> into WebKit.
> Here is a link to the whatwg thread, with the proposal and use cases:
> http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-August/022113.html
> Here is an actual API:
> ---------------------------
> Page-level API
> var globalScript = new webkitGlobalScript(name, url, loadHandler,
> errorHandler);
> This returns a global scope object for the named Global Script.
> If one does not exist yet, creates a new one. The globalScript is
> sharing same process and same thread as the page running the constructor
> and is operational right away. No synchronization is necessary.
> Parameters:
> name - string identifying the global script. Scoped to the orogin.
> url  - the JS resource to load, if it was not yet loaded. If the Global
> Script is already loaded but from a different url - the error is raised.
> laodHandler - a function called asynchronously when the script is loaded
> (or if it was already loaded by another page)
> errorHandler - handler for loading errors, like violation of same-origin
> policy or network error
> The GlobalScript would create its own ScriptExecutionContext-derived
> context if it was not yet created, and start to load the script into it.
> Once the script is loaded, it is evaluated in the global scope of the Global
> Script and loadHandlers are executed. Other pages that create a Global
> Script with the same name in the same origin would get the same object back.
> The globalScript object returned from the constructor can be immediately
> used to set/retrieve properties and event handlers on it.
> API exposed to Global Script (on its global scope object)
> - Timers
> - XHR
> - Navigator
> - localStorage
> - Database
> - Workers
> -----------------------------
> Thanks,
> Dmitry
> _______________________________________________
> webkit-dev mailing list
> webkit-dev at lists.webkit.org
> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
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