Annotation of html5/workers/Overview.html, revision 1.250
1.242 ihickson 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"><!-- when publishing, change bits marked ZZZ --><html lang="en-US-x-Hixie"><title>Web Workers</title><style type="text/css">
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1.82 ihickson 143:
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1.218 ihickson 182: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><div class="head">
1.115 ihickson 183: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
1.54 ihickson 184: <h1>Web Workers</h1>
1.196 ihickson 185:
1.250 ! ihickson 186: <h2 class="no-num no-toc" id="editor-s-draft-11-may-2010">Editor's Draft 11 May 2010</h2>
1.218 ihickson 187: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 188: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 189: <dt>Latest Editor's Draft:</dt>
1.115 ihickson 190: <dd><a href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 191: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 192: <dt>Previous Versions:</dt>
1.113 ihickson 193: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20090423/">http://www.w3.org/TR/2009/WD-workers-20090423/</a>
1.198 ihickson 194: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20091029/">http://www.w3.org/TR/2009/WD-workers-20091029/</a></dd>
1.117 ihickson 195: <!-- :ZZZ -->
1.81 ihickson 196: <dt>Editors:</dt>
1.115 ihickson 197: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 198: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
1.234 ihickson 199: © 2010 <a href="http://www.w3.org/"><abbr title="World Wide
1.155 ihickson 200: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 201: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
202: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
203: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
204: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
205: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 206: use</a> rules apply.</p>
1.201 ihickson 207:
1.155 ihickson 208: </div><hr class="top"><h2 class="no-num no-toc" id="abstract">Abstract</h2><p>This specification defines an API that allows Web application
1.81 ihickson 209: authors to spawn background workers running scripts in parallel to
210: their main page. This allows for thread-like operation with
1.212 ihickson 211: message-passing as the coordination mechanism.<h2 class="no-num no-toc" id="status-of-this-document">Status of This document</h2><!-- intro boilerplate (required) --><p><em>This section describes the status of this document at the
1.81 ihickson 212: time of its publication. Other documents may supersede this
213: document. A list of current W3C publications and the most recently
214: formally published revision of this technical report can be found in
1.115 ihickson 215: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.201 ihickson 216: at http://www.w3.org/TR/.</em></p><!-- where to send feedback (required) --><p>If you wish to make comments regarding this document, please send
1.115 ihickson 217: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 218: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 219: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 220:
221: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 222: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
223: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 224: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 225:
1.155 ihickson 226: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 227: stable. <strong>Implementors who are not taking part in the
228: discussions are likely to find the specification changing out from
229: under them in incompatible ways.</strong> Vendors interested in
230: implementing this specification before it eventually reaches the
231: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 232: mailing lists and take part in the discussions.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- version history or list of changes (required) --><p>The latest stable version of the editor's draft of this
1.115 ihickson 233: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
234: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 235: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 236: unfinished text in the process of being prepared) is available <a href="http://www.whatwg.org/specs/web-workers/current-work/">on the
1.81 ihickson 237: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 238: following locations:</p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><ul><li>Twitter messages (non-editorial changes only): <a href="http://twitter.com/WHATWG">http://twitter.com/WHATWG</a></li>
1.115 ihickson 239: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
240: <li>Commit-Watchers mailing list: <a href="http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org">http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></li>
241: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
242: <li>CVS log: <a href="http://dev.w3.org/cvsweb/html5/workers/Overview.html">http://dev.w3.org/cvsweb/html5/workers/Overview.html</a></li>
1.155 ihickson 243: </ul><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- status of document, group responsible (required) --><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Apps
1.81 ihickson 244: Working Group</a> is the W3C working group responsible for this
245: specification's progress along the W3C Recommendation track.
1.196 ihickson 246:
1.250 ! ihickson 247: This specification is the 11 May 2010 Editor's Draft.
1.155 ihickson 248: </p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- relationship to other work (required) --><p>This specification is also being produced by the <a href="http://www.whatwg.org/">WHATWG</a>. The two specifications are
249: identical from the table of contents onwards.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- context and rationale (required) --><p>This specification is intended to specify a part of the Web
1.81 ihickson 250: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 251: document primarily to ease the cognitive load on reviewers.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- required patent boilerplate --><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5
1.115 ihickson 252: February 2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/42538/status" rel="disclosure">public list of
1.81 ihickson 253: any patent disclosures</a> made in connection with the deliverables
254: of the group; that page also includes instructions for disclosing a
255: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 256: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
257: Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
1.214 ihickson 258: 6 of the W3C Patent Policy</a>.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- This text will be moved back to under the copyright in the header if this is not resolved by April 2010 --><p class="alt">The <a href="http://www.whatwg.org/specs/web-workers/current-work/">WHATWG
259: version</a> of this specification is available under a license that
260: permits reuse of the specification text.</p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><h2 class="no-num no-toc" id="contents">Table of Contents</h2>
1.81 ihickson 261: <!--begin-toc-->
1.115 ihickson 262: <ol class="toc">
263: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 264: <ol>
1.115 ihickson 265: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
266: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 267: <ol>
1.115 ihickson 268: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
269: <li><a href="#a-worker-for-updating-a-client-side-database"><span class="secno">1.2.2 </span>A worker for updating a client-side database</a></li>
270: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.3 </span>Worker used for background I/O</a></li>
1.238 ihickson 271: <li><a href="#shared-workers-introduction"><span class="secno">1.2.4 </span>Shared workers introduction</a></li>
272: <li><a href="#shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</a></li>
273: <li><a href="#delegation"><span class="secno">1.2.6 </span>Delegation</a></li>
274: <li><a href="#providing-libraries"><span class="secno">1.2.7 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 275: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 276: <ol>
1.148 ihickson 277: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
278: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
279: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
280: <ol>
281: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 282: <ol>
1.148 ihickson 283: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
284: <li><a href="#dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.1.2 </span>Dedicated workers and the <code>DedicatedWorkerGlobalScope</code> interface</a></li>
285: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> inteface</a></ol></li>
1.160 ihickson 286: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.186 ihickson 287: <li><a href="#the-event-loop"><span class="secno">4.3 </span>The event loop</a></li>
288: <li><a href="#the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</a></li>
289: <li><a href="#processing-model"><span class="secno">4.5 </span>Processing model</a></li>
290: <li><a href="#runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</a></li>
291: <li><a href="#creating-workers"><span class="secno">4.7 </span>Creating workers</a>
1.81 ihickson 292: <ol>
1.186 ihickson 293: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
294: <li><a href="#dedicated-workers-and-the-worker-interface"><span class="secno">4.7.2 </span>Dedicated workers and the <code>Worker</code> interface</a></li>
295: <li><a href="#shared-workers-and-the-sharedworker-interface"><span class="secno">4.7.3 </span>Shared workers and the <code>SharedWorker</code> interface</a></ol></ol></li>
1.148 ihickson 296: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 297: <ol>
1.148 ihickson 298: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
1.210 ihickson 299: <li><a href="#the-workernavigator-object"><span class="secno">5.2 </span>The <code>WorkerNavigator</code> object</a></li>
1.148 ihickson 300: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
301: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
302: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 303: <li><a class="no-num" href="#references">References</a></li>
304: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 305: <!--end-toc--><hr><h2 id="introduction"><span class="secno">1 </span>Introduction</h2><h3 id="scope"><span class="secno">1.1 </span>Scope</h3><p><i>This section is non-normative.</i><p>This specification defines an API for running scripts in the
306: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 307: scripts that respond to clicks or other user interactions, and
308: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 309: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 310: relatively heavy-weight, and are not intended to be used in large
311: numbers. For example, it would be inappropriate to launch one worker
312: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 313: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
314: start-up performance cost, and a high per-instance memory cost.<h3 id="tutorial"><span class="secno">1.2 </span>Tutorial</h3><p><i>This section is non-normative.</i><p>There are a variety of uses that workers can be put to. The
315: following subsections show various examples of this use.<h4 id="a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</h4><p><i>This section is non-normative.</i><p>The simplest use of workers is for performing a computationally
316: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
317: (naïvely) compute prime numbers, and progressively displays the
318: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 319: <html>
320: <head>
321: <title>Worker example: One-core computation</title>
322: </head>
323: <body>
324: <p>The highest prime number discovered so far is: <output id="result"></output></p>
325: <script>
1.50 ihickson 326: var worker = new Worker('worker.js');
327: worker.onmessage = function (event) {
1.54 ihickson 328: document.getElementById('result').textContent = event.data;
1.29 ihickson 329: };
1.81 ihickson 330: </script>
331: </body>
1.155 ihickson 332: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 333: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 334: representing that worker, which is used to communicate with the
1.177 ihickson 335: worker. That object's <code title="handler-Worker-onmessage"><a href="#handler-worker-onmessage">onmessage</a></code> event handler allows the code to receive messages from the worker.<p>The worker itself is as follows:<pre>var n = 1;
1.29 ihickson 336: search: while (true) {
337: n += 1;
338: for (var i = 2; i <= Math.sqrt(n); i += 1)
339: if (n % i == 0)
340: continue search;
341: // found a prime!
1.50 ihickson 342: postMessage(n);
1.155 ihickson 343: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 344: number. To send a message back to the page, the <code title="dom-DedicatedWorkerGlobalScope-postMessage"><a href="#dom-dedicatedworkerglobalscope-postmessage">postMessage()</a></code>
1.155 ihickson 345: method is used to post a message when a prime is found.<p><a href="http://www.whatwg.org/demos/workers/primes/page.html">View this example online</a>.<h4 id="a-worker-for-updating-a-client-side-database"><span class="secno">1.2.2 </span>A worker for updating a client-side database</h4><p><i>This section is non-normative.</i><p>In this example, the main document spawns a worker whose only
1.81 ihickson 346: task is to listen for notifications from the server, and, when
347: appropriate, either add or remove data from the client-side
1.155 ihickson 348: database.<p>Since no communication occurs between the worker and the main
349: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 350: new Worker('worker.js');
1.155 ihickson 351: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 352: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 353: server.onmessage = function (event) {
354: // data is in the format "command key value"
1.54 ihickson 355: var data = event.data.split(' ');
1.31 ihickson 356: switch (data[0]) {
357: case '+':
358: database.transaction(function(tx) {
359: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
360: });
361: case '-':
362: database.transaction(function(tx) {
363: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
364: });
365: }
1.155 ihickson 366: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 367: mechanism and opens the local database (which, we presume, has been
368: created earlier). The worker then just listens for messages from the
369: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 370: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 371: this example online</a>. (This example will not actually function,
372: since the server does not actually exist and the database is not
1.155 ihickson 373: created by this sample code.)<h4 id="worker-used-for-background-i-o"><span class="secno">1.2.3 </span>Worker used for background I/O</h4><p><i>This section is non-normative.</i><p>In this example, the main document uses two workers, one for
1.81 ihickson 374: fetching stock updates for at regular intervals, and one for
1.155 ihickson 375: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 376: <html>
377: <head>
378: <title>Worker example: Stock ticker</title>
379: <script>
1.33 ihickson 380: // TICKER
381: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 382: var ticker = new Worker('ticker.js');
1.33 ihickson 383:
384: // SEARCHER
1.50 ihickson 385: var searcher = new Worker('searcher.js');
1.33 ihickson 386: function search(query) {
1.50 ihickson 387: searcher.postMessage(query);
1.33 ihickson 388: }
389:
390: // SYMBOL SELECTION UI
391: function select(newSymbol) {
392: symbol = newSymbol;
1.50 ihickson 393: ticker.postMessage(symbol);
1.33 ihickson 394: }
1.81 ihickson 395: </script>
396: </head>
1.122 ihickson 397: <body onload="search('')">
1.81 ihickson 398: <p><output id="symbol"></output> <output id="value"></output></p>
399: <script>
1.50 ihickson 400: ticker.onmessage = function (event) {
1.54 ihickson 401: var data = event.data.split(' ');
1.33 ihickson 402: document.getElementById('symbol').textContent = data[0];
403: document.getElementById('value').textContent = data[1];
404: };
1.50 ihickson 405: ticker.postMessage(symbol);
1.81 ihickson 406: </script>
1.122 ihickson 407: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 408: <ul id="results"></ul>
409: <script>
1.50 ihickson 410: searcher.onmessage = function (event) {
1.54 ihickson 411: var data = event.data.split(' ');
1.33 ihickson 412: var results = document.getElementById('results');
413: while (results.hasChildNodes()) // clear previous results
414: results.removeChild(results.firstChild);
415: for (var i = 0; i < data.length; i += 1) {
416: // add a list item with a button for each result
417: var li = document.createElement('li');
418: var button = document.createElement('button');
419: button.value = data[i];
420: button.type = 'button';
421: button.onclick = function () { select(this.value); };
422: button.textContent = data[i];
423: li.appendChild(button);
424: results.appendChild(li);
425: }
426: };
1.81 ihickson 427: </script>
428: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
429: </body>
1.155 ihickson 430: </html></pre><p>The two workers use a common library for performing the actual
431: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 432: try {
433: var xhr = new XMLHttpRequest();
434: xhr.open('GET', url, false);
435: xhr.send();
436: return xhr.responseText;
437: } catch (e) {
438: return ''; // turn all errors into empty results
439: }
1.155 ihickson 440: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 441: var timer;
442: var symbol;
443: function update() {
1.50 ihickson 444: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 445: timer = setTimeout(update, 10000);
446: }
1.50 ihickson 447: onmessage = function (event) {
1.33 ihickson 448: if (timer)
449: clearTimeout(timer);
1.54 ihickson 450: symbol = event.data;
1.33 ihickson 451: update();
1.155 ihickson 452: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 453: onmessage = function (event) {
1.54 ihickson 454: postMessage(get('search.cgi?' + event.data));
1.238 ihickson 455: };</pre><p><a href="http://www.whatwg.org/demos/workers/stocks/page.html">View this example online</a>.<h4 id="shared-workers-introduction"><span class="secno">1.2.4 </span>Shared workers introduction</h4><p><i>This section is non-normative.</i><p>This section introduces shared workers using a Hello World
456: example. Shared workers use slightly different APIs, since each
457: worker can have multiple connections.<p>This first example shows how you connect to a worker and how a
458: worker can send a message back to the page when it connects to
1.239 ihickson 459: it. Received messages are displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
460: <title>Shared workers: demo 1</title>
461: <pre id="log">Log:</pre>
462: <script>
463: var worker = new SharedWorker('test.js');
464: var log = document.getElementById('log');
465: worker.port.onmessage = function(e) { // note: not worker.onmessage!
466: log.textContent += '\n' + e.data;
467: }
468: </script>
469: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
470: var port = e.ports[0];
471: port.postMessage('Hello World!');
472: }
1.245 ihickson 473: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/001.html">View this example online</a>.<hr><p>This second example extends the first one by changing two things:
1.238 ihickson 474: first, messages are received using <code title="">addEventListener()</code> instead of an <span title="event
475: handler IDL attributes">event handler IDL attribute</span>, and
476: second, a message is sent <em>to</em> the worker, causing the worker
477: to send another message in return. Received messages are again
1.239 ihickson 478: displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
1.240 ihickson 479: <title>Shared workers: demo 2</title>
1.239 ihickson 480: <pre id="log">Log:</pre>
481: <script>
482: var worker = new SharedWorker('test.js');
483: var log = document.getElementById('log');
1.240 ihickson 484: worker.port.addEventListener('message', function(e) {
1.239 ihickson 485: log.textContent += '\n' + e.data;
1.240 ihickson 486: }, false);
487: worker.port.start(); // note: need this when using addEventListener
488: worker.port.postMessage('ping');
1.239 ihickson 489: </script>
490: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
491: var port = e.ports[0];
492: port.postMessage('Hello World!');
1.240 ihickson 493: port.onmessage = function(e) {
494: port.postMessage('pong'); // not e.ports[0].postMessage!
495: // e.target.postMessage('pong'); would work also
496: }
1.239 ihickson 497: }
1.245 ihickson 498: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/002.html">View this example online</a>.<hr><p>Finally, the example is extended to show how two pages can
1.238 ihickson 499: connect to the same worker; in this case, the second page is merely
500: in an <code>iframe</code> on the first page, but the same principle
501: would apply to an entirely separate page in a separate
1.239 ihickson 502: <span>top-level browsing context</span>.<p>Here is the outer HTML page:<pre><!DOCTYPE HTML>
503: <title>Shared workers: demo 3</title>
504: <pre id="log">Log:</pre>
505: <script>
506: var worker = new SharedWorker('test.js');
507: var log = document.getElementById('log');
508: worker.port.addEventListener('message', function(e) {
509: log.textContent += '\n' + e.data;
510: }, false);
511: worker.port.start();
512: worker.port.postMessage('ping');
513: </script>
514: <iframe src="inner.html"></iframe>
515: </pre><p>Here is the inner HTML page:<pre><!DOCTYPE HTML>
516: <title>Shared workers: demo 3 inner frame</title>
517: <pre id=log>Inner log:</pre>
518: <script>
519: var worker = new SharedWorker('test.js');
520: var log = document.getElementById('log');
521: worker.port.onmessage = function(e) {
522: log.textContent += '\n' + e.data;
523: }
524: </script>
525: </pre><p>Here is the JavaScript worker:<pre>var count = 0;
526: onconnect = function(e) {
527: count += 1;
528: var port = e.ports[0];
529: port.postMessage('Hello World! You are connection #' + count);
530: port.onmessage = function(e) {
531: port.postMessage('pong');
532: }
533: }
1.245 ihickson 534: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/003.html">View this example online</a>.<h4 id="shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</h4><p><i>This section is non-normative.</i><p>In this example, multiple windows (viewers) can be opened that
1.81 ihickson 535: are all viewing the same map. All the windows share the same map
536: information, with a single worker coordinating all the viewers. Each
537: viewer can move around independently, but if they set any data on
1.155 ihickson 538: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
539: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 540: <html>
541: <head>
542: <title>Workers example: Multiviewer</title>
543: <script>
1.36 ihickson 544: function openViewer() {
545: window.open('viewer.html');
546: }
1.81 ihickson 547: </script>
548: </head>
549: <body>
550: <p><button type=button onclick="openViewer()">Open a new
551: viewer</button></p>
552: <p>Each viewer opens in a new window. You can have as many viewers
553: as you like, they all view the same data.</p>
554: </body>
1.155 ihickson 555: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 556: <html>
557: <head>
558: <title>Workers example: Multiviewer viewer</title>
559: <script>
1.50 ihickson 560: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 561:
562: // CONFIGURATION
563: function configure(event) {
1.54 ihickson 564: if (event.data.substr(0, 4) != 'cfg ') return;
565: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 566: // update display to mention our name is name
567: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
568: // no longer need this listener
1.43 ihickson 569: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 570: }
1.53 ihickson 571: worker.port.addEventListener('message', configure, false);
1.36 ihickson 572:
573: // MAP
574: function paintMap(event) {
1.54 ihickson 575: if (event.data.substr(0, 4) != 'map ') return;
576: var data = event.data.substr(4).split(',');
1.36 ihickson 577: // display tiles data[0] .. data[8]
578: var canvas = document.getElementById('map');
579: var context = canvas.getContext('2d');
580: for (var y = 0; y < 3; y += 1) {
581: for (var x = 0; x < 3; x += 1) {
582: var tile = data[y * 3 + x];
583: if (tile == '0')
584: context.fillStyle = 'green';
585: else
586: context.fillStyle = 'maroon';
587: fillRect(x * 50, y * 50, 50, 50);
588: }
589: }
590: }
1.53 ihickson 591: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 592:
593: // PUBLIC CHAT
594: function updatePublicChat(event) {
1.54 ihickson 595: if (event.data.substr(0, 4) != 'txt ') return;
596: var name = event.data.substr(4).split(' ', 1);
597: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 598: // display "<name> message" in public chat
1.36 ihickson 599: var dialog = document.getElementById('public');
600: var dt = document.createElement('dt');
601: dt.textContent = name;
602: dialog.appendChild(dt);
603: var dd = document.createElement('dd');
604: dd.textContent = message;
605: dialog.appendChild(dd);
606: }
1.53 ihickson 607: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 608:
609: // PRIVATE CHAT
610: function startPrivateChat(event) {
1.54 ihickson 611: if (event.data.substr(0, 4) != 'msg ') return;
612: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 613: var port = event.ports[0];
1.36 ihickson 614: // display a private chat UI
615: var ul = document.getElementById('private');
616: var li = document.createElement('li');
617: var h3 = document.createElement('h3');
618: h3.textContent = 'Private chat with ' + name;
619: li.appendChild(h3);
620: var dialog = document.createElement('dialog');
621: var addMessage = function(name, message) {
622: var dt = document.createElement('dt');
623: dt.textContent = name;
624: dialog.appendChild(dt);
625: var dd = document.createElement('dd');
626: dd.textContent = message;
627: dialog.appendChild(dd);
628: };
629: port.onmessage = function (event) {
1.54 ihickson 630: addMessage(name, event.data);
1.36 ihickson 631: };
632: li.appendChild(dialog);
633: var form = document.createElement('form');
634: var p = document.createElement('p');
635: var input = document.createElement('input');
636: input.size = 50;
637: p.appendChild(input);
638: p.appendChild(document.createTextNode(' '));
639: var button = document.createElement('button');
640: button.textContent = 'Post';
641: p.appendChild(button);
642: form.onsubmit = function () {
643: port.postMessage(input.value);
644: addMessage('me', input.value);
645: input.value = '';
646: return false;
647: };
648: form.appendChild(p);
649: li.appendChild(form);
650: }
1.53 ihickson 651: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 652:
653: worker.port.start();
1.81 ihickson 654: </script>
655: </head>
656: <body>
657: <h1>Viewer</h1>
658: <h2>Map</h2>
659: <p><canvas id="map" height=150 width=150></canvas></p>
660: <p>
661: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
662: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
663: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
664: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
665: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
666: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
667: </p>
668: <h2>Public Chat</h2>
669: <dialog id="public"></dialog>
670: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
671: <p>
672: <input type="text" name="message" size="50">
673: <button>Post</button>
674: </p>
675: </form>
676: <h2>Private Chat</h2>
677: <ul id="private"></ul>
678: </body>
679: </html>
1.155 ihickson 680: </pre><p>There are several key things worth noting about the way the
681: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 682: processing function, the code here attaches multiple event
683: listeners, each one performing a quick check to see if it is
684: relevant for the message. In this example it doesn't make much
685: difference, but if multiple authors wanted to collaborate using a
686: single port to communicate with a worker, it would allow for
687: independent code instead of changes having to all be made to a
1.155 ihickson 688: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 689: unregister specific listeners when you are done with them, as is
690: done with the <code title="">configure()</code> method in this
1.155 ihickson 691: example.<p>Finally, the worker:<pre>
692: var nextName = 0;
1.36 ihickson 693: function getNextName() {
694: // this could use more friendly names
695: // but for now just return a number
696: return nextName++;
697: }
698:
699: var map = [
700: [0, 0, 0, 0, 0, 0, 0],
701: [1, 1, 0, 1, 0, 1, 1],
702: [0, 1, 0, 1, 0, 0, 0],
703: [0, 1, 0, 1, 0, 1, 1],
704: [0, 0, 0, 1, 0, 0, 0],
705: [1, 0, 0, 1, 1, 1, 1],
706: [1, 1, 0, 1, 1, 0, 1],
707: ];
708:
709: function wrapX(x) {
710: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 711: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 712: return x;
713: }
714:
715: function wrapY(y) {
716: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 717: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 718: return y;
719: }
720:
1.50 ihickson 721: function sendMapData(callback) {
1.36 ihickson 722: var data = '';
723: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
724: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
725: if (data != '')
726: data += ',';
727: data += map[y][x];
728: }
729: }
1.50 ihickson 730: callback('map ' + data);
1.36 ihickson 731: }
732:
733: var viewers = {};
734: onconnect = function (event) {
1.84 ihickson 735: event.ports[0]._name = getNextName();
736: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
737: viewers[event.ports[0]._name] = event.port._data;
738: event.ports[0].postMessage('cfg ' + name);
739: event.ports[0].onmessage = getMessage;
740: sendMapData(event.ports[0].postMessage);
1.36 ihickson 741: };
742:
743: function getMessage(event) {
1.54 ihickson 744: switch (event.data.substr(0, 4)) {
1.36 ihickson 745: case 'mov ':
1.54 ihickson 746: var direction = event.data.substr(4);
1.36 ihickson 747: var dx = 0;
748: var dy = 0;
749: switch (direction) {
750: case 'up': dy = -1; break;
751: case 'down': dy = 1; break;
752: case 'left': dx = -1; break;
753: case 'right': dx = 1; break;
754: }
755: event.target._data.x = wrapX(event.target._data.x + dx);
756: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 757: sendMapData(event.target.postMessage);
1.36 ihickson 758: break;
759: case 'set ':
1.54 ihickson 760: var value = event.data.substr(4);
1.36 ihickson 761: map[event.target._data.y][event.target._data.x] = value;
762: for (var viewer in viewers)
1.50 ihickson 763: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 764: break;
765: case 'txt ':
766: var name = event.target._name;
1.54 ihickson 767: var message = event.data.substr(4);
1.36 ihickson 768: for (var viewer in viewers)
769: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
770: break;
771: case 'msg ':
772: var party1 = event._data;
1.54 ihickson 773: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 774: if (party2) {
775: var channel = new MessageChannel();
1.84 ihickson 776: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
777: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 778: }
779: break;
780: }
1.155 ihickson 781: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 782: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 783: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 784: "msg" message from one viewer naming another viewer, it sets up a
785: direct connection between the two, so that the two viewers can
786: communicate directly without the worker having to proxy all the
1.238 ihickson 787: messages.<p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View this example online</a>.<h4 id="delegation"><span class="secno">1.2.6 </span>Delegation</h4><p><i>This section is non-normative.</i><p>With multicore CPUs becoming prevalent, one way to obtain better
1.81 ihickson 788: performance is to split computationally expensive tasks amongst
789: multiple workers. In this example, a computationally expensive task
790: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 791: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 792: <html>
793: <head>
1.203 ihickson 794: <title>Worker example: Multicore computation</title>
1.81 ihickson 795: </head>
796: <body>
1.203 ihickson 797: <p>Result: <output id="result"></output></p>
1.81 ihickson 798: <script>
1.50 ihickson 799: var worker = new Worker('worker.js');
800: worker.onmessage = function (event) {
1.54 ihickson 801: document.getElementById('result').textContent = event.data;
1.40 ihickson 802: };
1.81 ihickson 803: </script>
804: </body>
1.155 ihickson 805: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 806: var num_workers = 10;
807: var items_per_worker = 1000000;
808:
809: // start the workers
810: var result = 0;
811: var pending_workers = num_workers;
812: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 813: var worker = new Worker('core.js');
814: worker.postMessage(i * items_per_worker);
815: worker.postMessage((i+1) * items_per_worker);
816: worker.onmessage = storeResult;
1.40 ihickson 817: }
818:
819: // handle the results
820: function storeResult(event) {
1.54 ihickson 821: result += 1*event.data;
1.40 ihickson 822: pending_workers -= 1;
823: if (pending_workers <= 0)
1.50 ihickson 824: postMessage(result); // finished!
1.155 ihickson 825: }</pre><p>It consists of a loop to start the subworkers, and then a handler
826: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 827: onmessage = getStart;
1.40 ihickson 828: function getStart(event) {
1.54 ihickson 829: start = 1*event.data;
1.40 ihickson 830: onmessage = getEnd;
831: }
832:
833: var end;
834: function getEnd(event) {
1.54 ihickson 835: end = 1*event.data;
1.40 ihickson 836: onmessage = null;
1.66 ihickson 837: work();
1.40 ihickson 838: }
839:
1.66 ihickson 840: function work() {
1.40 ihickson 841: var result = 0;
842: for (var i = start; i < end; i += 1) {
843: // perform some complex calculation here
844: result += 1;
845: }
1.50 ihickson 846: postMessage(result);
847: close();
1.155 ihickson 848: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 849: for the range of numbers thus specified, and then report the result
1.238 ihickson 850: back to the parent.<p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.<h4 id="providing-libraries"><span class="secno">1.2.7 </span>Providing libraries</h4><p><i>This section is non-normative.</i><p>Suppose that a cryptography library is made available that
1.155 ihickson 851: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 852:
853: <dd>Takes a port, on which it will send two messages, first the
854: public key and then the private key.</dd>
855:
856: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
857:
858: <dd>Takes a port, to which any number of messages can be sent, the
859: first giving the public key, and the remainder giving the
860: plaintext, each of which is encrypted and then sent on that same
861: channel as the cyphertext. The user can close the port when it is
862: done encrypting content.</dd>
863:
864: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
865:
866: <dd>Takes a port, to which any number of messages can be sent, the
867: first giving the private key, and the remainder giving the
868: cyphertext, each of which is decrypted and then sent on that same
869: channel as the plaintext. The user can close the port when it is
870: done decrypting content.</dd>
1.49 ihickson 871:
1.155 ihickson 872: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 873: if (e.data == "genkeys")
1.84 ihickson 874: genkeys(e.ports[0]);
1.54 ihickson 875: else if (e.data == "encrypt")
1.84 ihickson 876: encrypt(e.ports[0]);
1.54 ihickson 877: else if (e.data == "decrypt")
1.84 ihickson 878: decrypt(e.ports[0]);
1.49 ihickson 879: }
880:
881: function genkeys(p) {
882: var keys = _generateKeyPair();
883: p.postMessage(keys[0]);
884: p.postMessage(keys[1]);
885: }
886:
887: function encrypt(p) {
888: var key, state = 0;
889: p.onmessage = function (e) {
890: if (state == 0) {
1.54 ihickson 891: key = e.data;
1.49 ihickson 892: state = 1;
893: } else {
1.54 ihickson 894: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 895: }
896: };
897: }
898:
899: function decrypt(p) {
900: var key, state = 0;
901: p.onmessage = function (e) {
902: if (state == 0) {
1.54 ihickson 903: key = e.data;
1.49 ihickson 904: state = 1;
905: } else {
1.54 ihickson 906: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 907: }
908: };
909: }
910:
1.50 ihickson 911: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 912: if ('onmessage' in this) // dedicated worker
1.50 ihickson 913: onmessage = handleMessage;
914: else // shared worker
915: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 916:
917:
918: // the "crypto" functions:
919:
920: function _generateKeyPair() {
921: return [Math.random(), Math.random()];
922: }
923:
924: function _encrypt(k, s) {
925: return 'encrypted-' + k + ' ' + s;
926: }
927:
928: function _decrypt(k, s) {
929: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 930: }</pre><p>Note that the crypto functions here are just stubs and don't do
931: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 932: <html>
933: <head>
934: <title>Worker example: Crypto library</title>
935: <script>
1.50 ihickson 936: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 937: function getKeys() {
938: var state = 0;
1.50 ihickson 939: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 940: if (state == 0)
1.54 ihickson 941: document.getElementById('public').value = e.data;
1.49 ihickson 942: else if (state == 1)
1.54 ihickson 943: document.getElementById('private').value = e.data;
1.49 ihickson 944: state += 1;
945: };
946: }
947: function enc() {
1.50 ihickson 948: var port = cryptoLib.startConversation("encrypt");
949: port.postMessage(document.getElementById('public').value);
950: port.postMessage(document.getElementById('input').value);
951: port.onmessage = function (e) {
1.54 ihickson 952: document.getElementById('input').value = e.data;
1.50 ihickson 953: port.close();
1.49 ihickson 954: };
955: }
956: function dec() {
1.50 ihickson 957: var port = cryptoLib.startConversation("decrypt");
958: port.postMessage(document.getElementById('private').value);
959: port.postMessage(document.getElementById('input').value);
960: port.onmessage = function (e) {
1.54 ihickson 961: document.getElementById('input').value = e.data;
1.50 ihickson 962: port.close();
1.49 ihickson 963: };
964: }
1.81 ihickson 965: </script>
966: <style>
1.49 ihickson 967: textarea { display: block; }
1.81 ihickson 968: </style>
969: </head>
970: <body onload="getKeys()">
971: <fieldset>
972: <legend>Keys</legend>
973: <p><label>Public Key: <textarea id="public"></textarea></label></p>
974: <p><label>Private Key: <textarea id="private"></textarea></label></p>
975: </fieldset>
976: <p><label>Input: <textarea id="input"></textarea></label></p>
977: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
978: </body>
1.155 ihickson 979: </html></pre><p>A later version of the API, though, might want to offload all the
980: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 981: if (e.data == "genkeys")
1.84 ihickson 982: genkeys(e.ports[0]);
1.54 ihickson 983: else if (e.data == "encrypt")
1.84 ihickson 984: encrypt(e.ports[0]);
1.54 ihickson 985: else if (e.data == "decrypt")
1.84 ihickson 986: decrypt(e.ports[0]);
1.49 ihickson 987: }
988:
989: function genkeys(p) {
1.50 ihickson 990: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 991: generator.postMessage('', [p]);
1.49 ihickson 992: }
993:
994: function encrypt(p) {
995: p.onmessage = function (e) {
1.54 ihickson 996: var key = e.data;
1.50 ihickson 997: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 998: encryptor.postMessage(key, [p]);
1.49 ihickson 999: };
1000: }
1001:
1002: function encrypt(p) {
1003: p.onmessage = function (e) {
1.54 ihickson 1004: var key = e.data;
1.50 ihickson 1005: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 1006: decryptor.postMessage(key, [p]);
1.49 ihickson 1007: };
1008: }
1009:
1.50 ihickson 1010: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 1011: if ('onmessage' in this) // dedicated worker
1.50 ihickson 1012: onmessage = handleMessage;
1013: else // shared worker
1.84 ihickson 1014: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 1015: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 1016: var k = _generateKeyPair();
1.84 ihickson 1017: e.ports[0].postMessage(k[0]);
1018: e.ports[0].postMessage(k[1]);
1.49 ihickson 1019: close();
1020: }
1.50 ihickson 1021:
1022: function _generateKeyPair() {
1023: return [Math.random(), Math.random()];
1.155 ihickson 1024: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 1025: var key = e.data;
1.84 ihickson 1026: e.ports[0].onmessage = function (e) {
1.54 ihickson 1027: var s = e.data;
1.50 ihickson 1028: postMessage(_encrypt(key, s));
1.49 ihickson 1029: }
1.50 ihickson 1030: }
1031:
1032: function _encrypt(k, s) {
1033: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 1034: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 1035: var key = e.data;
1.84 ihickson 1036: e.ports[0].onmessage = function (e) {
1.54 ihickson 1037: var s = e.data;
1.50 ihickson 1038: postMessage(_decrypt(key, s));
1.49 ihickson 1039: }
1.50 ihickson 1040: }
1041:
1042: function _decrypt(k, s) {
1043: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 1044: }</pre><p>Notice how the users of the API don't have to even know that this
1045: is happening — the API hasn't changed; the library can
1.81 ihickson 1046: delegate to subworkers without changing its API, even though it is
1.155 ihickson 1047: accepting data using message channels.<p><a href="http://www.whatwg.org/demos/workers/crypto/page.html">View this example online</a>.<h2 id="conformance-requirements"><span class="secno">2 </span>Conformance requirements</h2><p>All diagrams, examples, and notes in this specification are
1.81 ihickson 1048: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 1049: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 1050: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
1051: "OPTIONAL" in the normative parts of this document are to be
1052: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 1053: not appear in all uppercase letters in this specification. <a href="#refsRFC2119">[RFC2119]</a><p>Requirements phrased in the imperative as part of algorithms
1.81 ihickson 1054: (such as "strip any leading space characters" or "return false and
1055: abort these steps") are to be interpreted with the meaning of the
1056: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 1057: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 1058: attributes, methods or objects. Such requirements are to be
1.155 ihickson 1059: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 1060: may be implemented in any manner, so long as the end result is
1061: equivalent. (In particular, the algorithms defined in this
1062: specification are intended to be easy to follow, and not intended to
1.155 ihickson 1063: be performant.)<p>The only conformance class defined by this specification is user
1064: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 1065: otherwise unconstrained inputs, e.g. to prevent denial of service
1066: attacks, to guard against running out of memory, or to work around
1.229 ihickson 1067: platform-specific limitations.<p>When support for a feature is disabled (e.g. as an emergency
1068: measure to mitigate a security problem, or to aid in development, or
1069: for performance reasons), user agents must act as if they had no
1070: support for the feature whatsoever, and as if the feature was not
1071: mentioned in this specification. For example, if a particular
1072: feature is accessed via an attribute in a Web IDL interface, the
1073: attribute itself would be omitted from the objects that implement
1074: that interface — leaving the attribute on the object but
1075: making it return null or throw an exception is insufficient.<h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3><p>This specification relies on several other underlying
1.226 ihickson 1076: specifications.<dl><dt>HTML</dt>
1.49 ihickson 1077:
1.81 ihickson 1078: <dd>
1.49 ihickson 1079:
1.226 ihickson 1080: <p>Many fundamental concepts from HTML are used by this
1081: specification. <a href="#refsHTML">[HTML]</a></p>
1.49 ihickson 1082:
1.81 ihickson 1083: </dd>
1.1 ihickson 1084:
1.81 ihickson 1085: <dt>WebIDL</dt>
1.1 ihickson 1086:
1087: <dd>
1088:
1.81 ihickson 1089: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 1090: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 1091:
1.81 ihickson 1092: </dd>
1.1 ihickson 1093:
1.155 ihickson 1094: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 1095: <code title="">Foo</code> is actually an interface, is sometimes
1096: used instead of the more accurate "an object implementing the
1.155 ihickson 1097: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1098: scripts in Web applications, and does not necessarily imply the
1099: existence of an actual <code>Document</code> object or of any other
1100: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 1101: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1102: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1103: <em>setting</em> when a new value is assigned to it.<p>The term "JavaScript" is used to refer to ECMA262, rather than
1.103 ihickson 1104: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1105: widely known. <a href="#refsECMA262">[ECMA262]</a><h2 id="infrastructure"><span class="secno">4 </span>Infrastructure</h2><p>There are two kinds of workers; dedicated workers, and shared
1.81 ihickson 1106: workers. Dedicated workers, once created, and are linked to their
1107: creator; but message ports can be used to communicate from a
1108: dedicated worker to multiple other browsing contexts or
1109: workers. Shared workers, on the other hand, are named, and once
1110: created any script running in the same <span>origin</span> can
1.155 ihickson 1111: obtain a reference to that worker and communicate with it.<h3 id="the-global-scope"><span class="secno">4.1 </span>The global scope</h3><p>The global scope is the "inside" of a worker.<h4 id="the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> abstract interface</h4><pre class="idl">interface <dfn id="workerglobalscope">WorkerGlobalScope</dfn> {
1.115 ihickson 1112: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1113: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1114:
1115: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1116: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1117: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1118: };
1.172 ihickson 1119: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
1120: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <span>EventTarget</span>;</pre><p>The <dfn id="dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self"><code>self</code></dfn> attribute
1.155 ihickson 1121: must return the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.<p>The <dfn id="dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location"><code>location</code></dfn>
1.115 ihickson 1122: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1123: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1124: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1125: that was used to initialize the worker, after any redirects.<hr><p>When a script invokes the <dfn id="dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close"><code>close()</code></dfn>
1.123 ihickson 1126: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1127: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1128: have been added to the <span>event loop</span>'s <span title="task
1129: queue">task queues</span>.</p>
1130:
1131: <!-- v2-onclose
1132: <li><p><span>Queue a task</span> to <span>fire a simple
1.179 ihickson 1133: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1134: <code>WorkerGlobalScope</code> object.</p></li>
1135: -->
1.81 ihickson 1136:
1.115 ihickson 1137: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1138: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1139: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1140:
1.177 ihickson 1141: </ol><p>The following are the <span>event handlers</span> (and their
1142: corresponding <span title="event handler event type">event handler
1143: event types</span>) that must be supported, as IDL attributes, by
1144: objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1145: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1146: <tbody><!-- v2-onclose <tr><td><dfn title="handler-WorkerGlobalScope-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> --><tr><td><dfn id="handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.209 ihickson 1147: </table><hr><p>The <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface must not exist if
1148: the interface's <span>relevant namespace object</span> is a
1149: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h4 id="dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.1.2 </span>Dedicated workers and the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> interface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1150: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.174 ihickson 1151: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.77 ihickson 1152: <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1153: attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1154: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1155: had an implicit <code>MessagePort</code> associated with them. This
1156: port is part of a channel that is set up when the worker is created,
1157: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1158: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1159: at the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>The <dfn id="dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage"><code>postMessage()</code></dfn><!--
1.64 ihickson 1160: and <dfn
1161: title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
1.81 ihickson 1162: method<!--s (startConversation)--> on
1.115 ihickson 1163: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.81 ihickson 1164: invoked, it<!--/they (startConversation)--> immediately invoked the
1165: method of the same name on the port, with the same arguments, and
1.177 ihickson 1166: returned the same return value.<p>The following are the <span>event handlers</span> (and their
1167: corresponding <span title="event handler event type">event handler
1168: event types</span>) that must be supported, as IDL attributes, by
1169: objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1170: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1171: <tbody><tr><td><dfn id="handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1.191 ihickson 1172: </table><p>For the purposes of the <span>application cache</span> networking
1173: model, a dedicated worker is an extension of the <span>cache
1174: host</span> from which it was created.<h4 id="shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> inteface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1175: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1176: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1177: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.144 ihickson 1178: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1179: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1180: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1181: attribute must return the value it was assigned when the
1.115 ihickson 1182: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1183: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1184: that can be used to obtain a reference to the worker using the
1.177 ihickson 1185: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handlers</span> (and their
1186: corresponding <span title="event handler event type">event handler
1187: event types</span>) that must be supported, as IDL attributes, by
1188: objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1189: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1190: <tbody><tr><td><dfn id="handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect"><code>onconnect</code></dfn> <td> <code title="event-connect">connect</code>
1.191 ihickson 1191: </table><p>For the purposes of the <span>application cache</span> networking
1192: model, a shared worker is its own <span>cache host</span>. The
1193: <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1194: worker with an <span>application cache</span>.<p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
1.123 ihickson 1195: attribute returns the <code>ApplicationCache</code> object for the
1.101 ihickson 1196: worker.</p><!-- normative conf criteria is in the appcache section
1.160 ihickson 1197: --><h3 id="origins-of-workers"><span class="secno">4.2 </span>Origins of workers</h3><p>Both the <span>origin</span> and <span>effective script
1.81 ihickson 1198: origin</span> of scripts running in workers are the
1199: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1200: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.186 ihickson 1201: represents.<h3 id="the-event-loop"><span class="secno">4.3 </span>The event loop</h3><p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object has an <span>event
1.128 ihickson 1202: loop</span> distinct from those defined for <span title="unit of
1203: related similar-origin browsing contexts">units of related
1204: similar-origin browsing contexts</span>. This <span>event
1205: loop</span> has no associated <span>browsing context</span>, and its
1206: <span title="task queue">task queues</span> only have events,
1207: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1208: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1209: <a href="#run-a-worker">run a worker</a> algorithm.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object also has a <dfn id="dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</dfn> flag, which must
1.81 ihickson 1210: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1211: in the processing model section below.<p>Once the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set to
1.81 ihickson 1212: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1213: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1214: already on the queue are unaffected except where otherwise
1.115 ihickson 1215: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1216: timers stop firing, notifications for all pending asynchronous
1.186 ihickson 1217: operations are dropped, etc.<h3 id="the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</h3><p>Workers communicate with other workers and with <span title="browsing context">browsing contexts</span> through <span title="channel messaging">message channels</span> and their
1.155 ihickson 1218: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1219: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1220: consists of all the <code>MessagePort</code> objects that are
1221: entangled with another port and that have one (but only one) port
1222: owned by <var title="">worker global scope</var>. This list includes
1223: <!--all the <code>MessagePort</code> objects that are in events
1.68 ihickson 1224: pending in the <span>event loop</span>, as well as (commented out
1225: because in practice it makes no difference either way as far as I
1226: can tell, and it would be hard to strictly implement since these
1.81 ihickson 1227: ports might not yet be across the thread boundary)--> the implicit
1.155 ihickson 1228: <code>MessagePort</code> in the case of <a href="#dedicatedworkerglobalscope" title="DedicatedWorkerGlobalScope">dedicated workers</a>.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> also has a list of <dfn id="the-worker-s-workers">the
1.124 ihickson 1229: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1230: populated when the worker creates or obtains further workers.<p>Finally, each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> also has a list of
1.124 ihickson 1231: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1232: is empty; it is populated when the worker is created.<p>Whenever a <code>Document</code> <var title="">d</var> is <dfn id="add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">added to the
1.123 ihickson 1233: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1234: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1235: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1236: <var title="">d</var>, <a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's
1.123 ihickson 1237: documents">add <var title="">d</var> to <var title="">q</var>'s
1238: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.155 ihickson 1239: <code>Document</code>s</span></a>.</p><!-- suggestions welcome
1240: on making this sentence into understandable English --><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1241: Document">discarded</span>, it must be removed from the list of
1242: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.192 ihickson 1243: whose list contains that <code>Document</code>.<p>Given a <span>script's global object</span> <var title="">o</var>
1.123 ihickson 1244: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1245: <code>Document</code> objects to add</dfn> depends on the type of
1246: <var title="">o</var>. If <var title="">o</var> is a
1247: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1248: nested worker), then the relevant <code>Document</code>s are the
1249: <code>Document</code>s that are in <var title="">o</var>'s own list
1250: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a>. Otherwise, <var title="">o</var> is a <code>Window</code> object, and the relevant
1251: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1252: <span>active document</span> of the <code>Window</code> object <var title="">o</var>.<hr><p>A worker is said to be a <dfn id="permissible-worker">permissible worker</dfn> if its
1.123 ihickson 1253: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1254: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1255: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1256: timers, database transactions, or network connections, or its list
1.124 ihickson 1257: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1258: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1259: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1260: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1261: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1262: <code>Document</code>s</a> are <span>fully active</span>.<p>A worker is said to be a <dfn id="suspendable-worker">suspendable worker</dfn> if it is
1.123 ihickson 1263: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.186 ihickson 1264: <a href="#permissible-worker">permissible worker</a>.<h3 id="processing-model"><span class="secno">4.5 </span>Processing model</h3><p>When a user agent is to <dfn id="run-a-worker">run a worker</dfn> for a script with
1.232 ihickson 1265: <span>URL</span> <var title="">url</var>, a <span>browsing
1266: context</span> <var title="">owner browsing context</var>, a
1267: <code>Document</code> <var title="">owner document</var>, an
1268: <span>origin</span> <var title="">owner origin</var>, and with
1269: global scope <var title="">worker global scope</var>, it must run
1270: the following steps:<ol><li>
1.81 ihickson 1271:
1272: <p>Create a completely separate and parallel execution environment
1273: (i.e. a separate thread or process or equivalent construct), and
1.106 ihickson 1274: run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1275:
1276: </li>
1.4 ihickson 1277:
1.101 ihickson 1278: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1279: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1280: shared worker), and there are any <span title="relevant application
1281: cache">relevant application caches</span> that are identified by a
1282: manifest URL with the <span>same origin</span> as <var title="">url</var> and that have <var title="">url</var> as one of
1.115 ihickson 1283: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1284: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1285: cache</span> of those that match.</li>
1286:
1.4 ihickson 1287: <li>
1.52 ihickson 1288:
1.176 ihickson 1289: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>.</p>
1290: <!-- not http-origin privacy sensitive -->
1.81 ihickson 1291:
1.129 ihickson 1292: <p>If the attempt fails, or if the attempt involves any redirects
1293: to URIs that do not have the <span>same origin</span> as <var title="">url</var> (even if the final URI is at the <span>same
1294: origin</span> as the original <var title="">url</var>), then for
1295: each <code><a href="#worker">Worker</a></code> or <code><a href="#sharedworker">SharedWorker</a></code> object
1296: associated with <var title="">worker global scope</var>,
1297: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1298: named <code title="event-error">error</code> at that
1.129 ihickson 1299: object. Abort these steps.</p>
1.7 ihickson 1300:
1.186 ihickson 1301: <p>If the attempt succeeds, then convert the script resource to
1302: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.81 ihickson 1303:
1.68 ihickson 1304: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1305:
1.115 ihickson 1306: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1307: type of the script is ignored. Unlike with <code>script</code>
1308: elements, there is no way to override the type. It's always
1.170 ihickson 1309: assumed to be JavaScript.</p>
1.81 ihickson 1310:
1311: </li>
1.7 ihickson 1312:
1313: <li>
1.68 ihickson 1314:
1.115 ihickson 1315: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1316: created, as follows.</p>
1317:
1318: <p>Create a new <span>script execution environment</span>
1319: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1320:
1.68 ihickson 1321: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1322: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1323: entry-points</span>; set the <i>initial code entry-point</i> to
1324: the entry-point for any executable code to be immediately run.</p>
1325:
1326: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1327:
1328: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1329:
1.232 ihickson 1330: <p>Set the <span>script's document</span> to <var title="">owner
1331: document</var>.</p>
1332:
1.83 ihickson 1333: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1334: UTF-8. (This is just used for encoding non-ASCII characters in the
1335: query component of URLs.)</p>
1.68 ihickson 1336:
1337: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1338:
1.81 ihickson 1339: </li>
1.4 ihickson 1340:
1341: <li>
1.81 ihickson 1342:
1343: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1344: worker such that no sooner than it stops being either a
1345: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1346: worker</a>, and no later than it stops being a
1347: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1348: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1349: to true<!-- v2-onclose and <span title="queue a task">a task is
1.179 ihickson 1350: queued</span> to <span>fire a simple event</span> named <code
1.123 ihickson 1351: title="event-close">close</code> at <var title="">worker global
1352: scope</var>-->.</p>
1.81 ihickson 1353:
1354: </li>
1.9 ihickson 1355:
1356: <li>
1.7 ihickson 1357:
1.81 ihickson 1358: <p><strong>Suspending workers</strong>: Start monitoring the
1359: worker, such that whenever <var title="">worker global
1.115 ihickson 1360: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1361: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1362: agent suspends execution of script in that worker until such time
1.115 ihickson 1363: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1364: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1365: worker</a>.</p>
1.4 ihickson 1366:
1.81 ihickson 1367: </li>
1.68 ihickson 1368:
1369: <li>
1.4 ihickson 1370:
1.81 ihickson 1371: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1372: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1373: entry-point</i>, and let that run until it either returns, fails
1374: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1375: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1376: algorithms defined below.</p>
1377:
1.149 ihickson 1378: <!-- v2-onclose
1379: <p class="note">If the script gets aborted by the "<span>kill a
1380: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1381: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1382: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1383: for the <code title="message-close">close</code> event. The
1.149 ihickson 1384: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1385: events.</p>
1.149 ihickson 1386: -->
1.4 ihickson 1387:
1.81 ihickson 1388: </li>
1.4 ihickson 1389:
1.95 ihickson 1390: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1391: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1392: a dedicated worker), then enable the <span>port message
1393: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1394:
1.4 ihickson 1395: <li>
1.68 ihickson 1396:
1.115 ihickson 1397: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1398: loop</span>'s <span title="task queue">task queues</span> or <var title="">worker global scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1.81 ihickson 1399: to true.</p>
1.43 ihickson 1400:
1.81 ihickson 1401: </li>
1.4 ihickson 1402:
1403: <li>
1404:
1.81 ihickson 1405: <p>Run the oldest task on one of the <span>event loop</span>'s
1406: <span title="task queue">task queues</span>, if any. The user
1407: agent may pick any <span>task queue</span>.</p>
1408:
1.115 ihickson 1409: <p class="note">The handling of events or the execution of
1410: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1411: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1412: defined below.</p>
1.8 ihickson 1413:
1.81 ihickson 1414: </li>
1.4 ihickson 1415:
1416: <li>
1417:
1.248 ihickson 1418: <p>If the <span>storage mutex</span> is now owned by the worker's
1419: <span>event loop</span>, release it so that it is once again
1420: free.</p>
1421:
1422: </li>
1423:
1424: <li>
1425:
1426: <p>Remove the task just run in the earlier step, if any, from its
1.81 ihickson 1427: <span>task queue</span>.</p>
1.4 ihickson 1428:
1.81 ihickson 1429: </li>
1.4 ihickson 1430:
1431: <li>
1.8 ihickson 1432:
1.81 ihickson 1433: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1434: <span title="task queue">task queues</span> or if <var title="">worker global scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1.81 ihickson 1435: to false, then jump back to the step above labeled <i>event
1436: loop</i>.</p>
1.8 ihickson 1437:
1.81 ihickson 1438: </li>
1.8 ihickson 1439:
1440: <li>
1.71 ihickson 1441:
1.123 ihickson 1442: <p>If there are any outstanding transactions that have callbacks
1443: that involve <span title="concept-script">scripts</span> whose
1444: <span title="script's global object">global object</span> is the
1445: <var title="">worker global scope</var>, roll them back (without
1446: invoking any of the callbacks).</p>
1.50 ihickson 1447:
1.123 ihickson 1448: </li>
1449:
1450: <li>
1451:
1452: <p>Empty the <var title="">worker global scope</var>'s <span>list
1453: of active timeouts</span> and its <span>list of active
1454: intervals</span>.</p>
1.50 ihickson 1455:
1.81 ihickson 1456: </li>
1.50 ihickson 1457:
1.247 ihickson 1458: <li>
1459:
1460: <p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1461: ports</a>.</p>
1462:
1463: </li>
1464:
1.123 ihickson 1465: <!-- v2-onclose
1.81 ihickson 1466: <li>
1.50 ihickson 1467:
1.123 ihickson 1468: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1469: object associated with <var title="">worker global scope</var>,
1470: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1471: named <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1472:
1.81 ihickson 1473: </li>
1.123 ihickson 1474: -->
1.155 ihickson 1475: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1476: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1477: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1478: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1479: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1480: false, <span>queue a task</span> to <span>fire a simple
1.179 ihickson 1481: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1482: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1483: --><li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1484: true.</li>
1485:
1.123 ihickson 1486: <!-- v2-onclose
1487: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1488: a worker</span>" processing model defined above immediately starts
1489: running event listeners registered for the <code
1490: title="event-close">close</code> event, this time should not be
1491: zero — the idea is that the <code
1492: title="event-close">close</code> event can be used to clean up
1493: when shutting down unexpectedly.</p></li>
1494: -->
1.81 ihickson 1495:
1.115 ihickson 1496: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1497: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1498: queue">task queues</span><!-- v2-onclose other than the <code
1499: title="event-close">close</code> event that this algorithm just
1500: added-->, discard them without processing them.</li>
1.81 ihickson 1501:
1.123 ihickson 1502: <!-- v2-onclose
1.115 ihickson 1503: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1504: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1505: the script currently running in the worker.</p></li>
1506: -->
1.81 ihickson 1507:
1508: <li><p>Wait a user-agent-defined amount of time.</li>
1509:
1.123 ihickson 1510: <li><p>Abort the script currently running in the worker<!--
1511: v2-onclose (if any script is running, then it will be a handler for
1512: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1513:
1.155 ihickson 1514: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1515: processing model on a worker at any time, e.g. in response to user
1516: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1517: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1518: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1519: set to true.<hr><p>When a user agent is to <dfn id="terminate-a-worker">terminate a worker</dfn> it must run
1.81 ihickson 1520: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1521: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1.115 ihickson 1522: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1523: true.</li>
1524:
1.115 ihickson 1525: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1526: queued in the <span>event loop</span>'s <span title="task
1527: queue">task queues</span>, discard them without processing
1528: them.</li>
1529:
1530: <li><p>Abort the script currently running in the worker.</li>
1531:
1.115 ihickson 1532: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1533: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1534: worker is a dedicated worker), then empty the <span>port message
1535: queue</span> of the port that the worker's implicit port is
1536: entangled with.</li>
1537:
1.155 ihickson 1538: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.186 ihickson 1539: <span>DOM manipulation task source</span>.<h3 id="runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</h3><p>Whenever an uncaught runtime script error occurs in one of the
1.143 ihickson 1540: worker's scripts, if the error did not occur while handling a
1541: previous script error, the user agent must <span>report the
1542: error</span> using the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code title="handler-WorkerGlobalScope-onerror"><a href="#handler-workerglobalscope-onerror">onerror</a></code>
1.205 ihickson 1543: attribute.
1544:
1.226 ihickson 1545: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1546:
1547: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1548: the error occurred while handling a previous script error, the error
1.215 ihickson 1549: may be reported to the user.
1.205 ihickson 1550:
1.226 ihickson 1551: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1552:
1553: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1554: the error occurred while handling a previous script error, the user
1.123 ihickson 1555: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1556: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1557: worker.<p>When the user agent is to <dfn id="fire-a-worker-error-event">fire a worker error event</dfn> at
1.118 ihickson 1558: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1559: the <code><a href="#errorevent">ErrorEvent</a></code> interface, with the name <code title="event-error">error</code>, that doesn't bubble and is
1.115 ihickson 1560: cancelable, with its <code title="dom-ErrorEvent-message"><a href="#dom-errorevent-message">message</a></code>, <code title="dom-ErrorEvent-filename"><a href="#dom-errorevent-filename">filename</a></code>, and <code title="dom-ErrorEvent-lineno"><a href="#dom-errorevent-lineno">lineno</a></code> attributes set
1.81 ihickson 1561: appropriately. The default action of this event depends on whether
1.115 ihickson 1562: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1563: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1564: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1565: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1.215 ihickson 1566: <em>that</em> worker. Otherwise, then the error may be reported
1.155 ihickson 1567: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1.233 ihickson 1568: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : <span>Event</span> {
1.147 ihickson 1569: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1570: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1571: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1572: void <a href="#dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent">initErrorEvent</a>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString messageArg, in DOMString filenameArg, in unsigned long linenoArg);
1.155 ihickson 1573: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.190 ihickson 1574: method must initialize the event in a manner analogous to the
1575: similarly-named method in the DOM Events interfaces. <a href="#refsDOMEVENTS">[DOMEVENTS]</a><p>The <dfn id="dom-errorevent-message" title="dom-ErrorEvent-message"><code>message</code></dfn>
1.155 ihickson 1576: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1577: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1578: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1579: attribute represents the line number where the error occurred in the
1.208 ihickson 1580: script.<h3 id="creating-workers"><span class="secno">4.7 </span>Creating workers</h3><h4 id="the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code><a href="#abstractworker">AbstractWorker</a></code> abstract interface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1581: interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1582: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1583: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.172 ihickson 1584: };
1.177 ihickson 1585: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handlers</span> (and their
1586: corresponding <span title="event handler event type">event handler
1587: event types</span>) that must be supported, as IDL attributes, by
1588: objects implementing the <code><a href="#abstractworker">AbstractWorker</a></code> interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1589: <tbody><tr><td><dfn id="handler-abstractworker-onerror" title="handler-AbstractWorker-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.123 ihickson 1590: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.186 ihickson 1591: </table><h4 id="dedicated-workers-and-the-worker-interface"><span class="secno">4.7.2 </span>Dedicated workers and the <code><a href="#worker">Worker</a></code> interface</h4><pre class="idl">[<a href="#dom-worker" title="dom-Worker">Constructor</a>(in DOMString scriptURL)]
1.115 ihickson 1592: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1593: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1594:
1.174 ihickson 1595: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1596: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1597: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1598: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1599: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1600: algorithm to be run on the worker with with the object is
1.155 ihickson 1601: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1602: <code>MessagePort</code> associated with them. This port is part of
1603: a channel that is set up when the worker is created, but it is not
1604: exposed. This object must never be garbage collected before the
1.155 ihickson 1605: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1606: at the <code><a href="#worker">Worker</a></code> object.<p>The <dfn id="dom-worker-postmessage" title="dom-Worker-postMessage"><code>postMessage()</code></dfn><!--
1.64 ihickson 1607: and <dfn
1608: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1609: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1610: must act as if, when invoked, it<!--/they (startConversation)-->
1611: immediately invoked the method of the same name on the port, with
1.177 ihickson 1612: the same arguments, and returned the same return value.<p>The following are the <span>event handlers</span> (and their
1613: corresponding <span title="event handler event type">event handler
1614: event types</span>) that must be supported, as IDL attributes, by
1615: objects implementing the <code><a href="#worker">Worker</a></code> interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1616: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1617: </table><hr><p>When the <dfn id="dom-worker" title="dom-Worker"><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
1.216 ihickson 1618: user agent must run the following steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument relative to the <span>entry
1.133 ihickson 1619: script</span>'s <span title="script's base URL">base URL</span>,
1620: when the method is invoked.</li>
1.9 ihickson 1621:
1.81 ihickson 1622: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1623: exception.</li>
1.9 ihickson 1624:
1.167 ihickson 1625: <li>
1626:
1627: <p>If the <span>origin</span> of the resulting <span>absolute
1628: URL</span> is not the <span title="same origin">same</span> as the
1.216 ihickson 1629: origin of the <span>entry script</span>, then throw a
1.182 ihickson 1630: <code>SECURITY_ERR</code> exception.</p>
1.167 ihickson 1631:
1632: <p class="note">Thus, scripts must be external files with the same
1633: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1634: URL, and a <code>http:</code> page couldn't start workers using
1635: scripts with <code>http:</code> URLs.</p>
1636:
1637: </li>
1.9 ihickson 1638:
1.185 ihickson 1639: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1640: object. Let <var title="">worker global scope</var> be this new
1641: object.</li>
1.9 ihickson 1642:
1.115 ihickson 1643: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1644: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1645:
1.185 ihickson 1646: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1647: owned by the <span title="script's global object">global
1648: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1649: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1650: port</var>.</li>
1.9 ihickson 1651:
1.81 ihickson 1652: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1653:
1.185 ihickson 1654: <li><p><span>Create a new <code>MessagePort</code> object</span>
1655: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1656:
1.81 ihickson 1657: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1658:
1.81 ihickson 1659: <li><p><span>Entangle</span> <var title="">outside port</var> and
1660: <var title="">inside port</var>.</li>
1.50 ihickson 1661:
1.81 ihickson 1662: <li><p>Return <var title="">worker</var>, and run the following
1663: steps asynchronously.</li>
1.50 ihickson 1664:
1.204 ihickson 1665: <!-- (this is done by the "run a worker" algorithm)
1.126 ihickson 1666: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.204 ihickson 1667: queue</span>.</p></li>
1668: -->
1.50 ihickson 1669:
1.126 ihickson 1670: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1671: queue</span>.</li>
1.50 ihickson 1672:
1673: <li>
1.51 ihickson 1674:
1.123 ihickson 1675: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1676: <code>Document</code> objects to add</a> given the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.123 ihickson 1677: constructor.</p>
1678:
1679: </li>
1680:
1681: <li>
1682:
1683: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1684: <var title="">worker global scope</var>'s list of <span>the
1685: worker's <code>Document</code>s</span></a> the
1686: <code>Document</code> objects in <var title="">docs</var>.</p>
1687:
1688: </li>
1689:
1690: <li>
1691:
1.192 ihickson 1692: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1693: of the <span title="concept-script">script</span> that invoked the
1694: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1695: are creating a nested worker), add <var title="">worker global
1696: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 1697: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object that is the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.124 ihickson 1698: constructor.</p>
1699:
1700: </li>
1701:
1702: <li>
1703:
1.115 ihickson 1704: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 1705: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 1706: script that invoked the method as the <var title="">owner browsing
1.232 ihickson 1707: context</var>, with the <span>script's document</span> of the
1708: script that invoked the method as the <var title="">owner
1709: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1710: script</span> as the <var title="">owner origin</var>, and with
1711: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1712:
1.81 ihickson 1713: </li>
1.4 ihickson 1714:
1.155 ihickson 1715: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1716: object</span> is either a <code>Window</code> object or an object
1.186 ihickson 1717: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<h4 id="shared-workers-and-the-sharedworker-interface"><span class="secno">4.7.3 </span>Shared workers and the <code><a href="#sharedworker">SharedWorker</a></code> interface</h4><pre class="idl">[<a href="#dom-sharedworker" title="dom-SharedWorker">Constructor</a>(in DOMString scriptURL, in optional DOMString name)]
1.115 ihickson 1718: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1719: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1720: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1721: attribute must return the value it was assigned by the object's
1722: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1723: communicating with the shared worker.<p>When the <dfn id="dom-sharedworker" title="dom-SharedWorker"><code>SharedWorker(<var title="">scriptURL</var>, <var title="">name</var>)</code></dfn>
1.81 ihickson 1724: constructor is invoked, the user agent must run the following
1.155 ihickson 1725: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1726:
1727: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1728: exception.</li>
1729:
1.159 ihickson 1730: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1731: resulting <span>absolute URL</span>.</li>
1732:
1733: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1734: argument, or the empty string if the second argument was
1735: omitted.</li>
1.159 ihickson 1736:
1.167 ihickson 1737: <li>
1738:
1739: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1740: not the <span title="same origin">same</span> as the origin of the
1.216 ihickson 1741: <span>entry script</span>, then throw a <code>SECURITY_ERR</code>
1.182 ihickson 1742: exception.</p>
1.167 ihickson 1743:
1744: <p class="note">Thus, scripts must be external files with the same
1745: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1746: URL, and a <code>http:</code> page couldn't start workers using
1747: scripts with <code>http:</code> URLs.</p>
1748:
1749: </li>
1.9 ihickson 1750:
1751: <li>
1752:
1.123 ihickson 1753: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1754: <code>Document</code> objects to add</a> given the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.123 ihickson 1755: constructor.</p>
1756:
1757: </li>
1758:
1759: <li>
1760:
1.50 ihickson 1761: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1762:
1.155 ihickson 1763: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1764: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1765: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1766:
1.185 ihickson 1767: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1768: owned by the <span title="script's global object">global
1769: object</span> of the script that invoked the method. Let this be
1.123 ihickson 1770: the <var title="">outside port</var>.</li>
1.81 ihickson 1771:
1.115 ihickson 1772: <li><p>Assign <var title="">outside port</var> to the <code title="dom-SharedWorker-port"><a href="#dom-sharedworker-port">port</a></code> attribute of <var title="">worker</var>.</li>
1.81 ihickson 1773:
1.164 ihickson 1774: <li><p>Let <var title="">worker global scope</var> be
1775: null.</li>
1776:
1777: <li><p>If <var title="">name</var> is not the empty string and
1778: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1779: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1780: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1781: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1782: represents an <span>absolute URL</span> with the <span>same
1783: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1784: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1785:
1786: <li><p>Otherwise, if <var title="">name</var> is the empty string
1787: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1788: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1789: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.237 ihickson 1790: represents an <span>absolute URL</span> that is exactly equal to
1791: <var title="">scriptURL</var>, then let <var title="">worker
1792: global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1793: object.</li>
1.164 ihickson 1794:
1.9 ihickson 1795: <li>
1796:
1.164 ihickson 1797: <p>If <var title="">worker global scope</var> is not null, then
1798: run these steps:</p>
1.81 ihickson 1799:
1.164 ihickson 1800: <ol><li><p>If <var title="">worker global scope</var>'s <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code>
1.81 ihickson 1801: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1802: exactly equal to <var title="">scriptURL</var>, then throw a
1803: <code>URL_MISMATCH_ERR</code> exception and abort all these
1804: steps.</li>
1.81 ihickson 1805:
1806: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1807:
1.185 ihickson 1808: <li><p><span>Create a new <code>MessagePort</code>
1809: object</span> owned by <var title="">worker global
1810: scope</var>. Let this be the <var title="">inside
1811: port</var>.</li>
1.81 ihickson 1812:
1813: <li><p><span>Entangle</span> <var title="">outside port</var>
1814: and <var title="">inside port</var>.</li>
1815:
1816: <li><p>Return <var title="">worker</var> and perform the next
1817: step asynchronously.</li>
1.9 ihickson 1818:
1.81 ihickson 1819: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1820: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1821: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1822: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1823: value is an array containing only the newly created port, and
1824: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1825:
1.123 ihickson 1826: <li>
1827:
1828: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1829: <var title="">worker global scope</var>'s list of <span>the
1830: worker's <code>Document</code>s</span></a> the
1831: <code>Document</code> objects in <var title="">docs</var>.</p>
1832:
1833: </li>
1834:
1.124 ihickson 1835: <li>
1836:
1.192 ihickson 1837: <p>If the <span title="script's global object">global
1838: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1839: that invoked the constructor is a
1840: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to the list of <a href="#the-worker-s-workers">the
1841: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1842: object that is the <span title="script's global object">global
1843: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1844: that invoked the constructor.</p>
1845:
1846: </li>
1847:
1.81 ihickson 1848: <li><p>Abort all these steps.</li>
1.9 ihickson 1849:
1.155 ihickson 1850: </ol></li>
1.9 ihickson 1851:
1.185 ihickson 1852: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1853: object. Let <var title="">worker global scope</var> be this new
1854: object.</li>
1.9 ihickson 1855:
1.81 ihickson 1856: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1857:
1.115 ihickson 1858: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1859: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1860:
1.185 ihickson 1861: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.81 ihickson 1862: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1863:
1.81 ihickson 1864: <li><p><span>Entangle</span> <var title="">outside port</var> and
1865: <var title="">inside port</var>.</li>
1.9 ihickson 1866:
1.155 ihickson 1867: </ol></li>
1.28 ihickson 1868:
1.123 ihickson 1869: <li><p>Return <var title="">worker</var> and perform the remaining
1870: steps asynchronously.</li>
1.18 ihickson 1871:
1.81 ihickson 1872: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1873: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1874: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1875: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1876: is an array containing only the newly created port, and <span>queue
1877: a task</span> to dispatch the event at <var title="">worker global
1878: scope</var>.</li>
1.26 ihickson 1879:
1880: <li>
1.46 ihickson 1881:
1.123 ihickson 1882: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1883: <var title="">worker global scope</var>'s list of <span>the
1884: worker's <code>Document</code>s</span></a> the
1885: <code>Document</code> objects in <var title="">docs</var>.</p>
1886:
1887: </li>
1888:
1889: <li>
1890:
1.192 ihickson 1891: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1892: of the <span title="concept-script">script</span> that invoked the
1893: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to the list of <a href="#the-worker-s-workers">the
1894: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1895: object that is the <span title="script's global object">global
1896: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1897: that invoked the constructor.</p>
1898:
1899: </li>
1900:
1901: <li>
1902:
1.159 ihickson 1903: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 1904: with the <span>script's browsing context</span> of the script that
1.159 ihickson 1905: invoked the method as the <var title="">owner browsing
1.232 ihickson 1906: context</var>, with the <span>script's document</span> of the
1907: script that invoked the method as the <var title="">owner
1908: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1909: script</span> as the <var title="">owner origin</var>, and with
1910: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1911:
1.60 ihickson 1912: </li>
1.81 ihickson 1913:
1.155 ihickson 1914: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1915: object</span> is either a <code>Window</code> object or an object
1.155 ihickson 1916: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1917: <span>DOM manipulation task source</span>.<h2 id="apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</h2><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1918: interface <dfn id="workerutils">WorkerUtils</dfn> {
1919: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.210 ihickson 1920: readonly attribute <a href="#workernavigator">WorkerNavigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 1921: };
1.184 ihickson 1922: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1923: objects, etc) are not available to workers in this version of this
1.155 ihickson 1924: specification.<h3 id="importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</h3><p>When a script invokes the <dfn id="dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts"><code>importScripts(<var title="">urls</var>)</code></dfn> method on a
1.115 ihickson 1925: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1926: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1927: anything. Abort these steps.</li>
1928:
1929: <li><p><span title="resolve a url">Resolve</span> each
1930: argument.</li>
1931:
1932: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1933: exception.</li>
1934:
1935: <!--
1.67 ihickson 1936: <li><p>If any of the resulting <span title="absolute URL">absolute
1937: URLs</span> have an <span>origin</span> that is not the <span
1938: title="same origin">same</span> as the origin of the script that
1.182 ihickson 1939: invoked the method, then throw a <code>SECURITY_ERR</code>
1940: exception.</p></li>
1.67 ihickson 1941: -->
1.26 ihickson 1942:
1943: <li>
1.81 ihickson 1944:
1.45 ihickson 1945: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 1946: resulting <span title="absolute URL">absolute URLs</span>, from
1.216 ihickson 1947: the <span>entry script</span>'s <span>origin</span>.</p> <!-- not
1.176 ihickson 1948: http-origin privacy sensitive -->
1.81 ihickson 1949:
1950: </li>
1.26 ihickson 1951:
1952: <li>
1953:
1.81 ihickson 1954: <p>For each argument in turn, in the order given, starting with
1955: the first one, run these substeps:</p>
1.26 ihickson 1956:
1.155 ihickson 1957: <ol><li>
1.26 ihickson 1958:
1.81 ihickson 1959: <p>Wait for the fetching attempt for the corresponding resource
1960: to complete.</p>
1.60 ihickson 1961:
1.81 ihickson 1962: <p>If the fetching attempt failed, throw a
1963: <code>NETWORK_ERR</code> exception and abort all these
1964: steps.</p>
1.45 ihickson 1965:
1.186 ihickson 1966: <p>If the attempt succeeds, then convert the script resource to
1967: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.85 ihickson 1968:
1969: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1970:
1.115 ihickson 1971: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1972: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1973: type.</p>
1.61 ihickson 1974:
1.81 ihickson 1975: </li>
1.26 ihickson 1976:
1.81 ihickson 1977: <li>
1.26 ihickson 1978:
1.81 ihickson 1979: <p><span>Create a script</span>, using <var title="">source</var> as the script source and <var title="">language</var> as the scripting language, using the
1.189 ihickson 1980: same global object, browsing context, URL character encoding,
1981: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 1982: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1983:
1.115 ihickson 1984: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1985: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1986: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1987: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1988:
1.199 ihickson 1989: <p>If it failed to parse, then throw an ECMAScript
1990: <code>SyntaxError</code> exception and abort all these
1991: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 1992:
1.81 ihickson 1993: <p>If an exception was raised or if the script was prematurely
1994: aborted, then abort all these steps, letting the exception or
1995: aborting continue to be processed by the script that called the
1.115 ihickson 1996: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 1997: method.</p>
1998:
1.115 ihickson 1999: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 2000: worker</a>" algorithms abort the script then abort all these
2001: steps.</p>
2002:
2003: </li>
2004:
1.155 ihickson 2005: </ol></li>
1.152 ihickson 2006:
1.210 ihickson 2007: </ol><h3 id="the-workernavigator-object"><span class="secno">5.2 </span>The <code><a href="#workernavigator">WorkerNavigator</a></code> object</h3><p>The <dfn id="dom-worker-navigator" title="dom-worker-navigator"><code>navigator</code></dfn> attribute
1.115 ihickson 2008: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1.210 ihickson 2009: the <code><a href="#workernavigator">WorkerNavigator</a></code> interface, which represents the
2010: identity and state of the user agent (the client):<pre class="idl">interface <dfn id="workernavigator">WorkerNavigator</dfn> {};
2011: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorID</span>;
2012: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorOnLine</span>;</pre><p>Objects implementing the <code><a href="#workernavigator">WorkerNavigator</a></code> interface
2013: also implement the <code>NavigatorID</code> and
2014: <code>NavigatorOnLine</code> interfaces.
1.205 ihickson 2015:
1.226 ihickson 2016: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2017:
1.210 ihickson 2018: <p>This <code><a href="#workernavigator">WorkerNavigator</a></code> interface must not exist if the
2019: interface's <span>relevant namespace object</span> is a
2020: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h3 id="apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</h3><p>The <code title="dom-opendatabase">openDatabase()</code> and
1.115 ihickson 2021: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.200 ihickson 2022: methods are defined in the Web SQL Database specification. <a href="#refsWEBSQL">[WEBSQL]</a><h3 id="interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</h3><p>There must be no interface objects and constructors available in
1.192 ihickson 2023: the global scope of scripts whose <span>script's global
2024: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 2025: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 2026: constructors defined by the XMLHttpRequest specifications, except
2027: that the <span>document response entity body</span> must always be
1.160 ihickson 2028: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
2029: <span>script's base URL</span>; the
2030: <span><code>XMLHttpRequest</code> origin</span> is the script's
2031: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 2032:
1.205 ihickson 2033: <li><p>The interface objects and constructors defined by this
2034: specification.</li>
1.119 ihickson 2035:
1.205 ihickson 2036: <li><p>Constructors defined by specifications that explicitly say
2037: that they should be visible when the <span>script's global
2038: object</span> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>, a
2039: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>, or an object implementing the
2040: <code><a href="#workerutils">WorkerUtils</a></code> interface; the interfaces of any objects
2041: with such constructors; and the interfaces of any objects made
2042: accessible through APIs exposed by those constructors or made
2043: accessible through interfaces to be implemented by any objects that
2044: are themselves accessible to scripts whose <span>script's global
2045: object</span> implements the <code><a href="#workerutils">WorkerUtils</a></code>
2046: interface.</li>
2047:
2048: </ul><p class="note">These requirements do not override the requirements
2049: defined by the Web IDL specification, in particular concerning the
2050: visibility of interfaces annotated with the <code title="">[NoInterfaceObject]</code> extended attribute.<h3 id="worker-locations"><span class="secno">5.5 </span>Worker locations</h3><pre class="idl">interface <dfn id="workerlocation">WorkerLocation</dfn> {
1.115 ihickson 2051: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
2052: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
2053: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
2054: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
2055: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
2056: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
2057: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
2058: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 2059: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
2060: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 2061: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 2062: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 2063: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 2064: <dfn id="dom-workerlocation-host" title="dom-WorkerLocation-host"><code>host</code></dfn>, <dfn id="dom-workerlocation-port" title="dom-WorkerLocation-port"><code>port</code></dfn>, <dfn id="dom-workerlocation-hostname" title="dom-WorkerLocation-hostname"><code>hostname</code></dfn>,
2065: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
2066: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
2067: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
1.163 ihickson 2068: follow the rules given for URL decomposition IDL attributes, with the
1.115 ihickson 2069: <span title="concept-uda-input">input</span> being the
1.81 ihickson 2070: <span>absolute URL</span> that the object represents (same as the
1.115 ihickson 2071: <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and
2072: the <span title="concept-uda-setter">common setter action</span>
1.205 ihickson 2073: being a no-op, since the attributes are defined to be readonly.
2074:
1.226 ihickson 2075: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2076:
1.209 ihickson 2077: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface must not exist if the
2078: interface's <span>relevant namespace object</span> is a
1.226 ihickson 2079: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h2 class="no-num" id="references">References</h2><!--REFS--><p>All references are normative unless marked "Non-normative".</p><!-- Dates are only included for standards older than the Web,
2080: because the newer ones keep changing. --><dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.153 ihickson 2081: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
2082: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
2083: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1.226 ihickson 2084: S. Byrnes. W3C.</dd>
1.153 ihickson 2085: <!--
2086: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
1.226 ihickson 2087: DOM Core</a></cite>, S. Pieters. W3C.</dd>
1.153 ihickson 2088: -->
2089:
1.152 ihickson 2090: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
2091: <!--
2092: <dd><cite><a
2093: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
2094: Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2095: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C.</dd>
1.152 ihickson 2096: -->
2097: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
2098: Object Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2099: D. Schepers. W3C.</dd>
1.152 ihickson 2100:
2101: <dt id="refsECMA262">[ECMA262]</dt>
2102: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1.226 ihickson 2103: Language Specification</a></cite>. ECMA.</dd>
1.152 ihickson 2104:
1.226 ihickson 2105: <dt id="refsHTML">[HTML]</dt>
2106: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML</a></cite>,
2107: I. Hickson. WHATWG.</dd>
1.152 ihickson 2108:
1.154 ihickson 2109: <dt id="refsRFC2119">[RFC2119]</dt>
2110: <dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
1.226 ihickson 2111: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF.</dd>
1.154 ihickson 2112:
2113: <dt id="refsWEBIDL">[WEBIDL]</dt>
2114: <!--
2115: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
1.226 ihickson 2116: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2117: -->
2118: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
1.226 ihickson 2119: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2120:
1.230 ihickson 2121: <dt id="refsWEBSQL">[WEBSQL]</dt>
2122: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web SQL
2123: Database</a></cite>, I. Hickson. W3C.</dd>
2124:
1.152 ihickson 2125: <dt id="refsXHR">[XHR]</dt>
2126: <!--
2127: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
1.226 ihickson 2128: Object</a></cite>, A. van Kesteren. W3C.</dd>
1.152 ihickson 2129: -->
1.160 ihickson 2130: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.226 ihickson 2131: A. van Kesteren. W3C.</dd>
1.152 ihickson 2132:
1.221 ihickson 2133: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2134:
2135: Aaron Boodman,
1.155 ihickson 2136: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2137: Anne van Kesteren,
2138: Ben Turner,
2139: Dmitry Titov,
1.96 ihickson 2140: Drew Wilson,
1.97 ihickson 2141: Jeremy Orlow,
1.81 ihickson 2142: Jonas Sicking,
2143: Justin James,
2144: Kevin Hakanson,
2145: Maciej Stachowiak,
2146: Michael Nordman,
2147: Mike Smith,
2148:
2149: and
2150:
2151: Philip Taylor
2152:
1.155 ihickson 2153: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2154: technology and whose experience has been a huge influence on this
1.155 ihickson 2155: specification.
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