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Re: Transferable Objects, was: Re: Web Messaging Intents, was: Re: [DRAFT] Web Intents Task Force Charter

From: Charles Pritchard <chuck@jumis.com>
Date: Fri, 18 Nov 2011 14:42:58 -0800
Message-ID: <4EC6DF72.8050705@jumis.com>
To: Paul Kinlan <paulkinlan@google.com>
CC: timeless <timeless@gmail.com>, Greg Billock <gbillock@google.com>, WebIntents <public-web-intents@w3.org>
Thanks for exploring this complex use case. This is an edge case, and I 
appreciate you taking the time.

Here's my understanding:

The following sends an entangled port through intents. The client can 
then dispatch a Transferable ArrayBuffer.

var channel = new MessageChannel();
var intent = new Intent("http://webintents.org/transfer",
   "application/octet-stream+myprotocol", channel.port2);
channel.port1.onmessage = function (event) {
   if(event.data == "OK")
   channel.port1.postMessage("DATA", [myArrayBuffer], event.origin);
};
window.navigator.startActivity(intent);

This extra work is to ensure the ArrayBuffer is neutered:
http://www.khronos.org/registry/typedarray/specs/latest/#9.2


-Charles

On 11/18/11 1:52 PM, Paul Kinlan wrote:
> The Pseudo code you have is nearly exactly how we envisaged it.  We 
> just passed the port, then the data over the port as that could be 
> part of the lower level protocol (the 'myprotocol' bit).
>
>
> P
>
> On Fri, Nov 18, 2011 at 10:40 PM, Charles Pritchard <chuck@jumis.com 
> <mailto:chuck@jumis.com>> wrote:
>
>     Carrying this thread over to the web intents mailing list.
>
>     The current issue I'm asking about, in this thread, is how we
>     might present the postMessage transfer semantic in Web Intents.
>
>     Web Intents currently works much like postMessage(message). The
>     Transferable semantic is relatively new to Web Messaging
>     and allows the transfer of Array Buffer objects and MessagePorts.
>
>     In pseudo-code:
>
>     var intent = new Intent("http://webintents.org/transfer",
>       "application/octet-stream+myprotocol",
>      [messagePort, arrayBuffer]);
>
Received on Friday, 18 November 2011 22:43:33 UTC

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