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RemoteDocumentMessaging: Difference between revisions

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<pre>
<pre>
partial interface Window {
[Constructor(DOMString name)]
     MessagePort connectTo(DOMString target);
interface BroadcastChannel : EventTarget {
     void postMessage(any message);
    void close();
 
    attribute EventHandler onmessage;
};
};
</pre>
</pre>
The <code>connectTo</code> method opens a message port to a browsing context with name <code>target</code> within the caller's origin (although not necessarily within the caller's unit of related browsing contexts).
# Create a new MessagePort object owned by the global object of the incumbent script. Let this be the outside port.
# Return the outside port and continue executing the following steps asynchronously.


==Examples==
==Examples==


===Listener===
<pre>
// The channel name, "deep-thoughts", is scoped to the current origin.
var channel = new BroadcastChannel("deep-thoughts");


<pre>
channel.addEventListener("message", function(message) {
window.addEventListener("connect", function(message) {
   // Do something interesting with |message|, which is a MessageEvent.
   // message.source is a MessagePort we can use to talk to the remote message, just like in a shared worker.
  var remote = message.source;
  remote.postMessage("Welcome!");
  // You can call remote.addEventListener("message", ... ) to continue communicating with the remote window.
}, false);
}, false);


// Naming your window makes you discoverable by other documents in your origin.
// Send a message to each other BroadcastChannel instance with the same channel
window.name = "the-listener";
// name in the same origin.
channel.postMessage("I think, therefore I am.");
</pre>
</pre>


===Sender===
==Notes==
 
<pre>
var port = window.connectTo("the-listener");


port.addEventListener("message", function(message) {
You can already accomplish this through localStorage as that broadcasts storage events: http://bens.me.uk/2013/localstorage-inter-window-messaging Something that does not involve synchronous IO would probably be better though.
  if (message.data == "Welcome!")
    alert("Success!);
}, false);
 
port.start();
</pre>


[[Category:Proposals]]
[[Category:Proposals]]

Latest revision as of 03:20, 23 June 2013

Overview

This document describes a proposal for discovering and communicating with "remote" documents. In particular, this proposal lets a web page communicate with another document even if the web page does not have a direct script connection to that document.

Use Cases

The user opens the same word processing document hosted by a document editing web site in two different browser windows. The document editing web site wants to ensure that edits in one window a reflected in the other window without needing to round-trip through the server (e.g., because the user is offline). Unfortunately, the documents are in different units of related browsing contexts, which means the two documents cannot form a direct script connection. Using remote document messaging, the two documents can discover each other and update each other about edits performed by the user.

Specification

[Constructor(DOMString name)]
interface BroadcastChannel : EventTarget {
    void postMessage(any message);
    void close();

    attribute EventHandler onmessage;
};

Examples

// The channel name, "deep-thoughts", is scoped to the current origin.
var channel = new BroadcastChannel("deep-thoughts");

channel.addEventListener("message", function(message) {
  // Do something interesting with |message|, which is a MessageEvent.
}, false);

// Send a message to each other BroadcastChannel instance with the same channel
// name in the same origin.
channel.postMessage("I think, therefore I am.");

Notes

You can already accomplish this through localStorage as that broadcasts storage events: http://bens.me.uk/2013/localstorage-inter-window-messaging Something that does not involve synchronous IO would probably be better though.

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