Annotation of html5/workers/Overview.html, revision 1.284
1.281 ihickson 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"><html lang="en-US-x-Hixie"><title>Web Workers</title><style type="text/css">
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1.82 ihickson 146:
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1.260 ihickson 185:
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1.268 ihickson 189: fieldset p { margin: 0.5em 0; }
1.266 ihickson 190:
1.271 ihickson 191: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><script type="text/javascript">
192: function getCookie(name) {
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1.283 ihickson 209: </script><div class="head" id="head">
1.115 ihickson 210: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
1.271 ihickson 211:
1.54 ihickson 212: <h1>Web Workers</h1>
1.281 ihickson 213:
1.284 ! ihickson 214: <h2 class="no-num no-toc" id="editor-s-draft-12-may-2011">Editor's Draft 12 May 2011</h2>
1.218 ihickson 215: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 216: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 217: <dt>Latest Editor's Draft:</dt>
1.260 ihickson 218: <dd><a class="latest-link" href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.284 ! ihickson 219:
1.2 ihickson 220: <dt>Previous Versions:</dt>
1.279 ihickson 221: <dd><a href="http://www.w3.org/TR/2011/WD-workers-20110310/">http://www.w3.org/TR/2011/WD-workers-20110310/</a></dd>
222: <dd><a href="http://www.w3.org/TR/2011/WD-workers-20110208/">http://www.w3.org/TR/2011/WD-workers-20110208/</a></dd>
1.198 ihickson 223: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20091029/">http://www.w3.org/TR/2009/WD-workers-20091029/</a></dd>
1.279 ihickson 224: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20090423/">http://www.w3.org/TR/2009/WD-workers-20090423/</a></dd>
1.117 ihickson 225: <!-- :ZZZ -->
1.271 ihickson 226: <dt>Editor:</dt>
1.115 ihickson 227: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 228: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
1.234 ihickson 229: © 2010 <a href="http://www.w3.org/"><abbr title="World Wide
1.155 ihickson 230: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 231: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
232: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
233: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
234: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
235: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 236: use</a> rules apply.</p>
1.201 ihickson 237:
1.254 ihickson 238:
1.252 ihickson 239: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.255 ihickson 240: <p class="alt">The bulk of the text of this specification is also
1.254 ihickson 241: available in the WHATWG <a href="http://www.whatwg.org/specs/web-apps/current-work/complete.html#workers">Web Applications 1.0</a> specification, under a license that permits
242: reuse of the specification text.</p>
1.252 ihickson 243: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
244:
1.254 ihickson 245:
1.155 ihickson 246: </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 247: authors to spawn background workers running scripts in parallel to
248: their main page. This allows for thread-like operation with
1.281 ihickson 249: message-passing as the coordination mechanism.<h2 class="no-num no-toc" id="status-of-this-document">Status of This document</h2><p><em>This section describes the status of this document at the
1.81 ihickson 250: time of its publication. Other documents may supersede this
251: document. A list of current W3C publications and the most recently
252: formally published revision of this technical report can be found in
1.115 ihickson 253: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.281 ihickson 254: at http://www.w3.org/TR/.</em></p><p>If you wish to make comments regarding this document in a manner
1.271 ihickson 255: that is tracked by the W3C, please submit them via using <a href="http://www.w3.org/Bugs/Public/enter_bug.cgi?product=HTML%20WG">our
256: public bug database</a>. If you do not have an account then you can
257: enter feedback using this form:<form action="http://www.whatwg.org/specs/web-apps/current-work/file-spam.cgi" method="post">
258: <fieldset><legend>Feedback Comments</legend>
259: <input name="id" type="hidden" value="top"><input name="component" type="hidden" value="Web Workers (editor: Ian Hickson)"><input name="response" type="hidden" value="html"><p><label for="feedbackBox">Please enter your feedback, carefully
260: indicating the title of the section for which you are submitting
261: feedback, quoting the text that's wrong today if appropriate. If
262: you're suggesting a new feature, it's really important to say
263: <em>what</em> the problem you're trying to solve is. That's more
264: important than the solution, in fact.</label></p>
265: <p><textarea cols="79" id="feedbackBox" name="text" rows="10"></textarea></p>
266: <p class="note">Please don't use section numbers as these tend to
267: change rapidly and make your feedback harder to understand.</p>
268: <script type="text/javascript">
269: function checkFeedbackForm(form) {
1.277 ihickson 270: if (form.elements.text.value.match(/^ *</)) {
271: alert('Please don\'t start your feedback with an angle bracket, instead explain what topic your feedback is about first.');
272: return true;
273: } else if (form.elements.text.value.match(/ [^ ]+ [^ ]+ [^ ]+ [^ ]+ /)) {
274: if (form.elements.text.value.match(/^Please enter your feedback, carefully/)) {
275: alert('Please enter your feedback, explaining what is wrong, and without repeating the instructions. Thanks!');
276: return true;
277: } else if (form.elements.text.value.match(/ [^ ]+ [^ ]+ [^ ]+ [^ ]+ /)) {
1.271 ihickson 278: form.action = "http://www.whatwg.org/specs/web-apps/current-work/file-bug.cgi";
279: return true;
280: } else {
281: alert('Please include significantly more detail about exactly what problem you are trying to solve.');
282: return false;
283: }
284: }
285: </script><p>
1.277 ihickson 286: <input onclick="return checkFeedbackForm(form)" type="submit" value="Submit feedback"><small>(Note: Your IP address and user agent will be publicly recorded for spam prevention purposes.)</small>
1.271 ihickson 287: </p>
288: </fieldset></form><p>You can also e-mail feedback to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a> (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
289: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>),
1.115 ihickson 290: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
291: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.281 ihickson 292: All feedback is welcome.</p><p>Implementors should be aware that this specification is not
1.81 ihickson 293: stable. <strong>Implementors who are not taking part in the
294: discussions are likely to find the specification changing out from
295: under them in incompatible ways.</strong> Vendors interested in
296: implementing this specification before it eventually reaches the
297: Candidate Recommendation stage should join the aforementioned
1.271 ihickson 298: mailing lists and take part in the discussions.<div id="multipage-common">
1.281 ihickson 299: </div><p>The latest
1.271 ihickson 300: stable version of the editor's draft of this specification is always
301: available on <a href="http://dev.w3.org/html5/workers/">the W3C CVS server</a>
302: and in the <a href="http://svn.whatwg.org/webapps/">WHATWG
303: Subversion repository</a>. The <a href="http://www.whatwg.org/specs/web-apps/current-work/complete.html">latest
304: editor's working copy</a> (which may contain unfinished text in the
305: process of being prepared) contains the latest draft text of this
306: specification (amongst others). For more details, please see the <a href="http://wiki.whatwg.org/wiki/FAQ#What_are_the_various_versions_of_the_spec.3F">WHATWG
307: FAQ</a>.<p>Notifications of changes to this specification are sent along
308: with notifications of changes to related specifications using the
309: following mechanisms:<dl><dt>E-mail notifications of changes</dt>
310: <dd>Commit-Watchers mailing list (complete source diffs): <a href="http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org">http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></dd>
311: <dt>Browsable version-control record of all changes:</dt>
312: <dd>CVSWeb interface with side-by-side diffs: <a href="http://dev.w3.org/cvsweb/html5/">http://dev.w3.org/cvsweb/html5/</a></dd>
313: <dd>Annotated summary with unified diffs: <a href="http://html5.org/tools/web-apps-tracker">http://html5.org/tools/web-apps-tracker</a></dd>
314: <dd>Raw Subversion interface: <code>svn checkout http://svn.whatwg.org/webapps/</code></dd>
315: </dl><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Applications
1.81 ihickson 316: Working Group</a> is the W3C working group responsible for this
317: specification's progress along the W3C Recommendation track.
1.284 ! ihickson 318: This specification is the 12 May 2011 Editor's Draft.
1.281 ihickson 319: </p><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 320: 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 321: any patent disclosures</a> made in connection with the deliverables
322: of the group; that page also includes instructions for disclosing a
323: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 324: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
325: Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
1.252 ihickson 326: 6 of the W3C Patent Policy</a>.<h2 class="no-num no-toc" id="contents">Table of Contents</h2>
1.115 ihickson 327: <ol class="toc">
328: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 329: <ol>
1.115 ihickson 330: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
331: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 332: <ol>
1.115 ihickson 333: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
334: <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>
335: <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 336: <li><a href="#shared-workers-introduction"><span class="secno">1.2.4 </span>Shared workers introduction</a></li>
337: <li><a href="#shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</a></li>
1.275 ihickson 338: <li><a href="#delegation"><span class="secno">1.2.6 </span>Delegation</a></ol></ol></li>
1.148 ihickson 339: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 340: <ol>
1.148 ihickson 341: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
342: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
343: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
344: <ol>
345: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 346: <ol>
1.148 ihickson 347: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
348: <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>
1.270 ihickson 349: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> interface</a></ol></li>
1.160 ihickson 350: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.186 ihickson 351: <li><a href="#the-event-loop"><span class="secno">4.3 </span>The event loop</a></li>
352: <li><a href="#the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</a></li>
353: <li><a href="#processing-model"><span class="secno">4.5 </span>Processing model</a></li>
354: <li><a href="#runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</a></li>
355: <li><a href="#creating-workers"><span class="secno">4.7 </span>Creating workers</a>
1.81 ihickson 356: <ol>
1.186 ihickson 357: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
358: <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>
359: <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 360: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 361: <ol>
1.148 ihickson 362: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
1.210 ihickson 363: <li><a href="#the-workernavigator-object"><span class="secno">5.2 </span>The <code>WorkerNavigator</code> object</a></li>
1.272 ihickson 364: <li><a href="#interface-objects-and-constructors"><span class="secno">5.3 </span>Interface objects and constructors</a></li>
365: <li><a href="#worker-locations"><span class="secno">5.4 </span>Worker locations</a></ol></li>
1.115 ihickson 366: <li><a class="no-num" href="#references">References</a></li>
367: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.281 ihickson 368: <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
1.155 ihickson 369: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 370: scripts that respond to clicks or other user interactions, and
371: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 372: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 373: relatively heavy-weight, and are not intended to be used in large
374: numbers. For example, it would be inappropriate to launch one worker
375: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 376: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
377: 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
378: 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
379: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
380: (naïvely) compute prime numbers, and progressively displays the
381: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 382: <html>
383: <head>
384: <title>Worker example: One-core computation</title>
385: </head>
386: <body>
387: <p>The highest prime number discovered so far is: <output id="result"></output></p>
388: <script>
1.50 ihickson 389: var worker = new Worker('worker.js');
390: worker.onmessage = function (event) {
1.54 ihickson 391: document.getElementById('result').textContent = event.data;
1.29 ihickson 392: };
1.81 ihickson 393: </script>
394: </body>
1.155 ihickson 395: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 396: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 397: representing that worker, which is used to communicate with the
1.177 ihickson 398: 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 399: search: while (true) {
400: n += 1;
401: for (var i = 2; i <= Math.sqrt(n); i += 1)
402: if (n % i == 0)
403: continue search;
404: // found a prime!
1.50 ihickson 405: postMessage(n);
1.155 ihickson 406: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.278 ihickson 407: number. To send a message back to the page, the <code title="dom-DedicatedWorkerGlobalScope-send">send()</code>
1.155 ihickson 408: 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 409: task is to listen for notifications from the server, and, when
410: appropriate, either add or remove data from the client-side
1.155 ihickson 411: database.<p>Since no communication occurs between the worker and the main
412: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 413: new Worker('worker.js');
1.155 ihickson 414: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 415: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 416: server.onmessage = function (event) {
417: // data is in the format "command key value"
1.54 ihickson 418: var data = event.data.split(' ');
1.31 ihickson 419: switch (data[0]) {
420: case '+':
421: database.transaction(function(tx) {
422: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
423: });
424: case '-':
425: database.transaction(function(tx) {
426: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
427: });
428: }
1.155 ihickson 429: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 430: mechanism and opens the local database (which, we presume, has been
431: created earlier). The worker then just listens for messages from the
432: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 433: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 434: this example online</a>. (This example will not actually function,
435: since the server does not actually exist and the database is not
1.155 ihickson 436: 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 437: fetching stock updates for at regular intervals, and one for
1.155 ihickson 438: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 439: <html>
440: <head>
441: <title>Worker example: Stock ticker</title>
442: <script>
1.33 ihickson 443: // TICKER
444: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 445: var ticker = new Worker('ticker.js');
1.33 ihickson 446:
447: // SEARCHER
1.50 ihickson 448: var searcher = new Worker('searcher.js');
1.33 ihickson 449: function search(query) {
1.50 ihickson 450: searcher.postMessage(query);
1.33 ihickson 451: }
452:
453: // SYMBOL SELECTION UI
454: function select(newSymbol) {
455: symbol = newSymbol;
1.50 ihickson 456: ticker.postMessage(symbol);
1.33 ihickson 457: }
1.81 ihickson 458: </script>
459: </head>
1.122 ihickson 460: <body onload="search('')">
1.81 ihickson 461: <p><output id="symbol"></output> <output id="value"></output></p>
462: <script>
1.50 ihickson 463: ticker.onmessage = function (event) {
1.54 ihickson 464: var data = event.data.split(' ');
1.33 ihickson 465: document.getElementById('symbol').textContent = data[0];
466: document.getElementById('value').textContent = data[1];
467: };
1.50 ihickson 468: ticker.postMessage(symbol);
1.81 ihickson 469: </script>
1.122 ihickson 470: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 471: <ul id="results"></ul>
472: <script>
1.50 ihickson 473: searcher.onmessage = function (event) {
1.54 ihickson 474: var data = event.data.split(' ');
1.33 ihickson 475: var results = document.getElementById('results');
476: while (results.hasChildNodes()) // clear previous results
477: results.removeChild(results.firstChild);
478: for (var i = 0; i < data.length; i += 1) {
479: // add a list item with a button for each result
480: var li = document.createElement('li');
481: var button = document.createElement('button');
482: button.value = data[i];
483: button.type = 'button';
484: button.onclick = function () { select(this.value); };
485: button.textContent = data[i];
486: li.appendChild(button);
487: results.appendChild(li);
488: }
489: };
1.81 ihickson 490: </script>
491: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
492: </body>
1.155 ihickson 493: </html></pre><p>The two workers use a common library for performing the actual
494: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 495: try {
496: var xhr = new XMLHttpRequest();
497: xhr.open('GET', url, false);
498: xhr.send();
499: return xhr.responseText;
500: } catch (e) {
501: return ''; // turn all errors into empty results
502: }
1.155 ihickson 503: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 504: var timer;
505: var symbol;
506: function update() {
1.50 ihickson 507: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 508: timer = setTimeout(update, 10000);
509: }
1.50 ihickson 510: onmessage = function (event) {
1.33 ihickson 511: if (timer)
512: clearTimeout(timer);
1.54 ihickson 513: symbol = event.data;
1.33 ihickson 514: update();
1.155 ihickson 515: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 516: onmessage = function (event) {
1.54 ihickson 517: postMessage(get('search.cgi?' + event.data));
1.238 ihickson 518: };</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
519: example. Shared workers use slightly different APIs, since each
520: worker can have multiple connections.<p>This first example shows how you connect to a worker and how a
521: worker can send a message back to the page when it connects to
1.239 ihickson 522: it. Received messages are displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
523: <title>Shared workers: demo 1</title>
524: <pre id="log">Log:</pre>
525: <script>
526: var worker = new SharedWorker('test.js');
527: var log = document.getElementById('log');
528: worker.port.onmessage = function(e) { // note: not worker.onmessage!
529: log.textContent += '\n' + e.data;
530: }
531: </script>
532: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
533: var port = e.ports[0];
534: port.postMessage('Hello World!');
535: }
1.259 ihickson 536: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/001/test.html">View this example online</a>.<hr><p>This second example extends the first one by changing two things:
1.238 ihickson 537: first, messages are received using <code title="">addEventListener()</code> instead of an <span title="event
538: handler IDL attributes">event handler IDL attribute</span>, and
539: second, a message is sent <em>to</em> the worker, causing the worker
540: to send another message in return. Received messages are again
1.239 ihickson 541: displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
1.240 ihickson 542: <title>Shared workers: demo 2</title>
1.239 ihickson 543: <pre id="log">Log:</pre>
544: <script>
545: var worker = new SharedWorker('test.js');
546: var log = document.getElementById('log');
1.240 ihickson 547: worker.port.addEventListener('message', function(e) {
1.239 ihickson 548: log.textContent += '\n' + e.data;
1.240 ihickson 549: }, false);
550: worker.port.start(); // note: need this when using addEventListener
551: worker.port.postMessage('ping');
1.239 ihickson 552: </script>
553: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
554: var port = e.ports[0];
555: port.postMessage('Hello World!');
1.240 ihickson 556: port.onmessage = function(e) {
557: port.postMessage('pong'); // not e.ports[0].postMessage!
558: // e.target.postMessage('pong'); would work also
559: }
1.239 ihickson 560: }
1.259 ihickson 561: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/002/test.html">View this example online</a>.<hr><p>Finally, the example is extended to show how two pages can
1.238 ihickson 562: connect to the same worker; in this case, the second page is merely
563: in an <code>iframe</code> on the first page, but the same principle
564: would apply to an entirely separate page in a separate
1.239 ihickson 565: <span>top-level browsing context</span>.<p>Here is the outer HTML page:<pre><!DOCTYPE HTML>
566: <title>Shared workers: demo 3</title>
567: <pre id="log">Log:</pre>
568: <script>
569: var worker = new SharedWorker('test.js');
570: var log = document.getElementById('log');
571: worker.port.addEventListener('message', function(e) {
572: log.textContent += '\n' + e.data;
573: }, false);
574: worker.port.start();
575: worker.port.postMessage('ping');
576: </script>
577: <iframe src="inner.html"></iframe>
578: </pre><p>Here is the inner HTML page:<pre><!DOCTYPE HTML>
579: <title>Shared workers: demo 3 inner frame</title>
580: <pre id=log>Inner log:</pre>
581: <script>
582: var worker = new SharedWorker('test.js');
583: var log = document.getElementById('log');
584: worker.port.onmessage = function(e) {
585: log.textContent += '\n' + e.data;
586: }
587: </script>
588: </pre><p>Here is the JavaScript worker:<pre>var count = 0;
589: onconnect = function(e) {
590: count += 1;
591: var port = e.ports[0];
592: port.postMessage('Hello World! You are connection #' + count);
593: port.onmessage = function(e) {
594: port.postMessage('pong');
595: }
596: }
1.259 ihickson 597: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/003/test.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 598: are all viewing the same map. All the windows share the same map
599: information, with a single worker coordinating all the viewers. Each
600: viewer can move around independently, but if they set any data on
1.155 ihickson 601: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
602: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 603: <html>
604: <head>
605: <title>Workers example: Multiviewer</title>
606: <script>
1.36 ihickson 607: function openViewer() {
608: window.open('viewer.html');
609: }
1.81 ihickson 610: </script>
611: </head>
612: <body>
613: <p><button type=button onclick="openViewer()">Open a new
614: viewer</button></p>
615: <p>Each viewer opens in a new window. You can have as many viewers
616: as you like, they all view the same data.</p>
617: </body>
1.155 ihickson 618: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 619: <html>
620: <head>
621: <title>Workers example: Multiviewer viewer</title>
622: <script>
1.50 ihickson 623: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 624:
625: // CONFIGURATION
626: function configure(event) {
1.54 ihickson 627: if (event.data.substr(0, 4) != 'cfg ') return;
628: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 629: // update display to mention our name is name
630: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
631: // no longer need this listener
1.43 ihickson 632: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 633: }
1.53 ihickson 634: worker.port.addEventListener('message', configure, false);
1.36 ihickson 635:
636: // MAP
637: function paintMap(event) {
1.54 ihickson 638: if (event.data.substr(0, 4) != 'map ') return;
639: var data = event.data.substr(4).split(',');
1.36 ihickson 640: // display tiles data[0] .. data[8]
641: var canvas = document.getElementById('map');
642: var context = canvas.getContext('2d');
643: for (var y = 0; y < 3; y += 1) {
644: for (var x = 0; x < 3; x += 1) {
645: var tile = data[y * 3 + x];
646: if (tile == '0')
647: context.fillStyle = 'green';
648: else
649: context.fillStyle = 'maroon';
650: fillRect(x * 50, y * 50, 50, 50);
651: }
652: }
653: }
1.53 ihickson 654: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 655:
656: // PUBLIC CHAT
657: function updatePublicChat(event) {
1.54 ihickson 658: if (event.data.substr(0, 4) != 'txt ') return;
659: var name = event.data.substr(4).split(' ', 1);
660: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 661: // display "<name> message" in public chat
1.36 ihickson 662: var dialog = document.getElementById('public');
663: var dt = document.createElement('dt');
664: dt.textContent = name;
665: dialog.appendChild(dt);
666: var dd = document.createElement('dd');
667: dd.textContent = message;
668: dialog.appendChild(dd);
669: }
1.53 ihickson 670: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 671:
672: // PRIVATE CHAT
673: function startPrivateChat(event) {
1.54 ihickson 674: if (event.data.substr(0, 4) != 'msg ') return;
675: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 676: var port = event.ports[0];
1.36 ihickson 677: // display a private chat UI
678: var ul = document.getElementById('private');
679: var li = document.createElement('li');
680: var h3 = document.createElement('h3');
681: h3.textContent = 'Private chat with ' + name;
682: li.appendChild(h3);
683: var dialog = document.createElement('dialog');
684: var addMessage = function(name, message) {
685: var dt = document.createElement('dt');
686: dt.textContent = name;
687: dialog.appendChild(dt);
688: var dd = document.createElement('dd');
689: dd.textContent = message;
690: dialog.appendChild(dd);
691: };
692: port.onmessage = function (event) {
1.54 ihickson 693: addMessage(name, event.data);
1.36 ihickson 694: };
695: li.appendChild(dialog);
696: var form = document.createElement('form');
697: var p = document.createElement('p');
698: var input = document.createElement('input');
699: input.size = 50;
700: p.appendChild(input);
701: p.appendChild(document.createTextNode(' '));
702: var button = document.createElement('button');
703: button.textContent = 'Post';
704: p.appendChild(button);
705: form.onsubmit = function () {
706: port.postMessage(input.value);
707: addMessage('me', input.value);
708: input.value = '';
709: return false;
710: };
711: form.appendChild(p);
712: li.appendChild(form);
713: }
1.53 ihickson 714: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 715:
716: worker.port.start();
1.81 ihickson 717: </script>
718: </head>
719: <body>
720: <h1>Viewer</h1>
721: <h2>Map</h2>
722: <p><canvas id="map" height=150 width=150></canvas></p>
723: <p>
724: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
725: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
726: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
727: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
728: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
729: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
730: </p>
731: <h2>Public Chat</h2>
732: <dialog id="public"></dialog>
733: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
734: <p>
735: <input type="text" name="message" size="50">
736: <button>Post</button>
737: </p>
738: </form>
739: <h2>Private Chat</h2>
740: <ul id="private"></ul>
741: </body>
742: </html>
1.155 ihickson 743: </pre><p>There are several key things worth noting about the way the
744: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 745: processing function, the code here attaches multiple event
746: listeners, each one performing a quick check to see if it is
747: relevant for the message. In this example it doesn't make much
748: difference, but if multiple authors wanted to collaborate using a
749: single port to communicate with a worker, it would allow for
750: independent code instead of changes having to all be made to a
1.155 ihickson 751: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 752: unregister specific listeners when you are done with them, as is
753: done with the <code title="">configure()</code> method in this
1.155 ihickson 754: example.<p>Finally, the worker:<pre>
755: var nextName = 0;
1.36 ihickson 756: function getNextName() {
757: // this could use more friendly names
758: // but for now just return a number
759: return nextName++;
760: }
761:
762: var map = [
763: [0, 0, 0, 0, 0, 0, 0],
764: [1, 1, 0, 1, 0, 1, 1],
765: [0, 1, 0, 1, 0, 0, 0],
766: [0, 1, 0, 1, 0, 1, 1],
767: [0, 0, 0, 1, 0, 0, 0],
768: [1, 0, 0, 1, 1, 1, 1],
769: [1, 1, 0, 1, 1, 0, 1],
770: ];
771:
772: function wrapX(x) {
773: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 774: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 775: return x;
776: }
777:
778: function wrapY(y) {
779: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 780: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 781: return y;
782: }
783:
1.50 ihickson 784: function sendMapData(callback) {
1.36 ihickson 785: var data = '';
786: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
787: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
788: if (data != '')
789: data += ',';
790: data += map[y][x];
791: }
792: }
1.50 ihickson 793: callback('map ' + data);
1.36 ihickson 794: }
795:
796: var viewers = {};
797: onconnect = function (event) {
1.84 ihickson 798: event.ports[0]._name = getNextName();
799: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
800: viewers[event.ports[0]._name] = event.port._data;
801: event.ports[0].postMessage('cfg ' + name);
802: event.ports[0].onmessage = getMessage;
803: sendMapData(event.ports[0].postMessage);
1.36 ihickson 804: };
805:
806: function getMessage(event) {
1.54 ihickson 807: switch (event.data.substr(0, 4)) {
1.36 ihickson 808: case 'mov ':
1.54 ihickson 809: var direction = event.data.substr(4);
1.36 ihickson 810: var dx = 0;
811: var dy = 0;
812: switch (direction) {
813: case 'up': dy = -1; break;
814: case 'down': dy = 1; break;
815: case 'left': dx = -1; break;
816: case 'right': dx = 1; break;
817: }
818: event.target._data.x = wrapX(event.target._data.x + dx);
819: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 820: sendMapData(event.target.postMessage);
1.36 ihickson 821: break;
822: case 'set ':
1.54 ihickson 823: var value = event.data.substr(4);
1.36 ihickson 824: map[event.target._data.y][event.target._data.x] = value;
825: for (var viewer in viewers)
1.50 ihickson 826: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 827: break;
828: case 'txt ':
829: var name = event.target._name;
1.54 ihickson 830: var message = event.data.substr(4);
1.36 ihickson 831: for (var viewer in viewers)
832: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
833: break;
834: case 'msg ':
835: var party1 = event._data;
1.54 ihickson 836: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 837: if (party2) {
838: var channel = new MessageChannel();
1.84 ihickson 839: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
840: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 841: }
842: break;
843: }
1.155 ihickson 844: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 845: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 846: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 847: "msg" message from one viewer naming another viewer, it sets up a
848: direct connection between the two, so that the two viewers can
849: communicate directly without the worker having to proxy all the
1.238 ihickson 850: 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 851: performance is to split computationally expensive tasks amongst
852: multiple workers. In this example, a computationally expensive task
853: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 854: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 855: <html>
856: <head>
1.203 ihickson 857: <title>Worker example: Multicore computation</title>
1.81 ihickson 858: </head>
859: <body>
1.203 ihickson 860: <p>Result: <output id="result"></output></p>
1.81 ihickson 861: <script>
1.50 ihickson 862: var worker = new Worker('worker.js');
863: worker.onmessage = function (event) {
1.54 ihickson 864: document.getElementById('result').textContent = event.data;
1.40 ihickson 865: };
1.81 ihickson 866: </script>
867: </body>
1.155 ihickson 868: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 869: var num_workers = 10;
870: var items_per_worker = 1000000;
871:
872: // start the workers
873: var result = 0;
874: var pending_workers = num_workers;
875: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 876: var worker = new Worker('core.js');
877: worker.postMessage(i * items_per_worker);
878: worker.postMessage((i+1) * items_per_worker);
879: worker.onmessage = storeResult;
1.40 ihickson 880: }
881:
882: // handle the results
883: function storeResult(event) {
1.54 ihickson 884: result += 1*event.data;
1.40 ihickson 885: pending_workers -= 1;
886: if (pending_workers <= 0)
1.50 ihickson 887: postMessage(result); // finished!
1.155 ihickson 888: }</pre><p>It consists of a loop to start the subworkers, and then a handler
889: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 890: onmessage = getStart;
1.40 ihickson 891: function getStart(event) {
1.54 ihickson 892: start = 1*event.data;
1.40 ihickson 893: onmessage = getEnd;
894: }
895:
896: var end;
897: function getEnd(event) {
1.54 ihickson 898: end = 1*event.data;
1.40 ihickson 899: onmessage = null;
1.66 ihickson 900: work();
1.40 ihickson 901: }
902:
1.66 ihickson 903: function work() {
1.40 ihickson 904: var result = 0;
905: for (var i = start; i < end; i += 1) {
906: // perform some complex calculation here
907: result += 1;
908: }
1.50 ihickson 909: postMessage(result);
910: close();
1.155 ihickson 911: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 912: for the range of numbers thus specified, and then report the result
1.281 ihickson 913: back to the parent.<p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.</p><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 914: non-normative, as are all sections explicitly marked non-normative.
1.281 ihickson 915: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
1.81 ihickson 916: "OPTIONAL" in the normative parts of this document are to be
917: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 918: 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 919: (such as "strip any leading space characters" or "return false and
920: abort these steps") are to be interpreted with the meaning of the
921: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 922: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 923: attributes, methods or objects. Such requirements are to be
1.155 ihickson 924: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 925: may be implemented in any manner, so long as the end result is
926: equivalent. (In particular, the algorithms defined in this
927: specification are intended to be easy to follow, and not intended to
1.155 ihickson 928: be performant.)<p>The only conformance class defined by this specification is user
929: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 930: otherwise unconstrained inputs, e.g. to prevent denial of service
931: attacks, to guard against running out of memory, or to work around
1.229 ihickson 932: platform-specific limitations.<p>When support for a feature is disabled (e.g. as an emergency
933: measure to mitigate a security problem, or to aid in development, or
934: for performance reasons), user agents must act as if they had no
935: support for the feature whatsoever, and as if the feature was not
936: mentioned in this specification. For example, if a particular
937: feature is accessed via an attribute in a Web IDL interface, the
938: attribute itself would be omitted from the objects that implement
939: that interface — leaving the attribute on the object but
940: 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 941: specifications.<dl><dt>HTML</dt>
1.49 ihickson 942:
1.81 ihickson 943: <dd>
1.49 ihickson 944:
1.226 ihickson 945: <p>Many fundamental concepts from HTML are used by this
946: specification. <a href="#refsHTML">[HTML]</a></p>
1.49 ihickson 947:
1.81 ihickson 948: </dd>
1.1 ihickson 949:
1.81 ihickson 950: <dt>WebIDL</dt>
1.1 ihickson 951:
952: <dd>
953:
1.81 ihickson 954: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 955: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 956:
1.81 ihickson 957: </dd>
1.1 ihickson 958:
1.155 ihickson 959: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 960: <code title="">Foo</code> is actually an interface, is sometimes
961: used instead of the more accurate "an object implementing the
1.155 ihickson 962: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 963: scripts in Web applications, and does not necessarily imply the
964: existence of an actual <code>Document</code> object or of any other
965: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 966: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 967: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 968: <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 969: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 970: 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 971: workers. Dedicated workers, once created, and are linked to their
972: creator; but message ports can be used to communicate from a
973: dedicated worker to multiple other browsing contexts or
974: workers. Shared workers, on the other hand, are named, and once
975: created any script running in the same <span>origin</span> can
1.155 ihickson 976: 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 977: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
978: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
979:
980: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.281 ihickson 981: attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 982: };
1.172 ihickson 983: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
984: <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 985: 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 986: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
987: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 988: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 989: 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 990: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 991: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 992: have been added to the <span>event loop</span>'s <span title="task
993: queue">task queues</span>.</p>
994:
1.81 ihickson 995:
1.115 ihickson 996: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
997: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 998: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 999:
1.177 ihickson 1000: </ol><p>The following are the <span>event handlers</span> (and their
1001: corresponding <span title="event handler event type">event handler
1002: event types</span>) that must be supported, as IDL attributes, by
1003: objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1004: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.281 ihickson 1005: <tbody><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 1006: </table><hr><p>The <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface must not exist if
1007: the interface's <span>relevant namespace object</span> is a
1008: <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 1009: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.281 ihickson 1010: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports); attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1011: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1012: had an implicit <code>MessagePort</code> associated with them. This
1013: port is part of a channel that is set up when the worker is created,
1014: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1015: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1.281 ihickson 1016: 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> method on
1.115 ihickson 1017: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.281 ihickson 1018: invoked, it immediately invoked the
1.81 ihickson 1019: method of the same name on the port, with the same arguments, and
1.177 ihickson 1020: returned the same return value.<p>The following are the <span>event handlers</span> (and their
1021: corresponding <span title="event handler event type">event handler
1022: event types</span>) that must be supported, as IDL attributes, by
1023: objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1024: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1025: <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 1026: </table><p>For the purposes of the <span>application cache</span> networking
1027: model, a dedicated worker is an extension of the <span>cache
1.270 ihickson 1028: host</span> from which it was created.<h4 id="shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.1.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> interface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1029: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1030: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1031: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.144 ihickson 1032: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1033: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1034: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1035: attribute must return the value it was assigned when the
1.115 ihickson 1036: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1037: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1038: that can be used to obtain a reference to the worker using the
1.177 ihickson 1039: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handlers</span> (and their
1040: corresponding <span title="event handler event type">event handler
1041: event types</span>) that must be supported, as IDL attributes, by
1042: objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1043: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1044: <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 1045: </table><p>For the purposes of the <span>application cache</span> networking
1046: model, a shared worker is its own <span>cache host</span>. The
1047: <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1048: worker with an <span>application cache</span>.<p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
1.123 ihickson 1049: attribute returns the <code>ApplicationCache</code> object for the
1.281 ihickson 1050: worker.</p><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 1051: origin</span> of scripts running in workers are the
1052: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1053: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.186 ihickson 1054: 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 1055: loop</span> distinct from those defined for <span title="unit of
1056: related similar-origin browsing contexts">units of related
1057: similar-origin browsing contexts</span>. This <span>event
1058: loop</span> has no associated <span>browsing context</span>, and its
1059: <span title="task queue">task queues</span> only have events,
1060: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1061: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1062: <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 1063: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1064: 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 1065: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1066: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1067: already on the queue are unaffected except where otherwise
1.115 ihickson 1068: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1069: timers stop firing, notifications for all pending asynchronous
1.186 ihickson 1070: 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 1071: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1072: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1073: consists of all the <code>MessagePort</code> objects that are
1074: entangled with another port and that have one (but only one) port
1075: owned by <var title="">worker global scope</var>. This list includes
1.281 ihickson 1076: the implicit
1.155 ihickson 1077: <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 1078: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1079: 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 1080: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1081: 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 1082: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1083: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1084: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1085: <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 1086: documents">add <var title="">d</var> to <var title="">q</var>'s
1087: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.281 ihickson 1088: <code>Document</code>s</span></a>.</p><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1089: Document">discarded</span>, it must be removed from the list of
1090: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.192 ihickson 1091: whose list contains that <code>Document</code>.<p>Given a <span>script's global object</span> <var title="">o</var>
1.123 ihickson 1092: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1093: <code>Document</code> objects to add</dfn> depends on the type of
1094: <var title="">o</var>. If <var title="">o</var> is a
1095: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1096: nested worker), then the relevant <code>Document</code>s are the
1097: <code>Document</code>s that are in <var title="">o</var>'s own list
1098: 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
1099: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1100: <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 1101: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1102: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1103: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1104: timers, database transactions, or network connections, or its list
1.124 ihickson 1105: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1106: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1107: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1108: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1109: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1110: <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 1111: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.186 ihickson 1112: <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 1113: <span>URL</span> <var title="">url</var>, a <span>browsing
1114: context</span> <var title="">owner browsing context</var>, a
1115: <code>Document</code> <var title="">owner document</var>, an
1116: <span>origin</span> <var title="">owner origin</var>, and with
1117: global scope <var title="">worker global scope</var>, it must run
1118: the following steps:<ol><li>
1.81 ihickson 1119:
1.274 ihickson 1120: <p>Create a separate parallel execution environment (i.e. a
1121: separate thread or process or equivalent construct), and run the
1122: rest of these steps asynchronously in that context.</p>
1.81 ihickson 1123:
1124: </li>
1.4 ihickson 1125:
1.101 ihickson 1126: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1127: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1128: shared worker), and there are any <span title="relevant application
1129: cache">relevant application caches</span> that are identified by a
1130: 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 1131: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1132: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1133: cache</span> of those that match.</li>
1134:
1.4 ihickson 1135: <li>
1.52 ihickson 1136:
1.256 ihickson 1137: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>,
1138: with the <i>synchronous flag</i> set and the <i>force same-origin
1.281 ihickson 1139: flag</i> set.</p>
1.256 ihickson 1140: <p>If the attempt fails, then for each <code><a href="#worker">Worker</a></code> or
1141: <code><a href="#sharedworker">SharedWorker</a></code> object associated with <var title="">worker global scope</var>, <span>queue a task</span> to
1142: <span>fire a simple event</span> named <code title="event-error">error</code> at that object. Abort these
1143: steps.</p>
1.7 ihickson 1144:
1.264 ihickson 1145: <p>If the attempt succeeds, then let <var title="">source</var> be
1146: the script resource <span>decoded as UTF-8, with error
1147: handling</span>.
1148:
1149: <a href="#refsHTML">[HTML]</a>
1150:
1151: </p>
1.81 ihickson 1152:
1.68 ihickson 1153: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1154:
1.115 ihickson 1155: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1156: type of the script is ignored. Unlike with <code>script</code>
1157: elements, there is no way to override the type. It's always
1.170 ihickson 1158: assumed to be JavaScript.</p>
1.81 ihickson 1159:
1160: </li>
1.7 ihickson 1161:
1162: <li>
1.68 ihickson 1163:
1.115 ihickson 1164: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1165: created, as follows.</p>
1166:
1167: <p>Create a new <span>script execution environment</span>
1168: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1169:
1.68 ihickson 1170: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1171: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1172: entry-points</span>; set the <i>initial code entry-point</i> to
1173: the entry-point for any executable code to be immediately run.</p>
1174:
1175: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1176:
1177: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1178:
1.232 ihickson 1179: <p>Set the <span>script's document</span> to <var title="">owner
1180: document</var>.</p>
1181:
1.83 ihickson 1182: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1183: UTF-8. (This is just used for encoding non-ASCII characters in the
1184: query component of URLs.)</p>
1.68 ihickson 1185:
1186: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1187:
1.81 ihickson 1188: </li>
1.4 ihickson 1189:
1190: <li>
1.81 ihickson 1191:
1192: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1193: worker such that no sooner than it stops being either a
1194: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1195: worker</a>, and no later than it stops being a
1196: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1197: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1.281 ihickson 1198: to true.</p>
1.81 ihickson 1199:
1200: </li>
1.9 ihickson 1201:
1202: <li>
1.7 ihickson 1203:
1.81 ihickson 1204: <p><strong>Suspending workers</strong>: Start monitoring the
1205: worker, such that whenever <var title="">worker global
1.115 ihickson 1206: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1207: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1208: agent suspends execution of script in that worker until such time
1.115 ihickson 1209: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1210: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1211: worker</a>.</p>
1.4 ihickson 1212:
1.81 ihickson 1213: </li>
1.68 ihickson 1214:
1215: <li>
1.4 ihickson 1216:
1.81 ihickson 1217: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1218: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1219: entry-point</i>, and let that run until it either returns, fails
1220: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1221: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1222: algorithms defined below.</p>
1223:
1.4 ihickson 1224:
1.81 ihickson 1225: </li>
1.4 ihickson 1226:
1.95 ihickson 1227: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1228: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1229: a dedicated worker), then enable the <span>port message
1230: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1231:
1.4 ihickson 1232: <li>
1.68 ihickson 1233:
1.115 ihickson 1234: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1235: 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 1236: to true.</p>
1.43 ihickson 1237:
1.81 ihickson 1238: </li>
1.4 ihickson 1239:
1240: <li>
1241:
1.81 ihickson 1242: <p>Run the oldest task on one of the <span>event loop</span>'s
1243: <span title="task queue">task queues</span>, if any. The user
1244: agent may pick any <span>task queue</span>.</p>
1245:
1.115 ihickson 1246: <p class="note">The handling of events or the execution of
1247: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1248: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1249: defined below.</p>
1.8 ihickson 1250:
1.81 ihickson 1251: </li>
1.4 ihickson 1252:
1253: <li>
1254:
1.248 ihickson 1255: <p>If the <span>storage mutex</span> is now owned by the worker's
1256: <span>event loop</span>, release it so that it is once again
1257: free.</p>
1258:
1259: </li>
1260:
1261: <li>
1262:
1263: <p>Remove the task just run in the earlier step, if any, from its
1.81 ihickson 1264: <span>task queue</span>.</p>
1.4 ihickson 1265:
1.81 ihickson 1266: </li>
1.4 ihickson 1267:
1268: <li>
1.8 ihickson 1269:
1.81 ihickson 1270: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1271: <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 1272: to false, then jump back to the step above labeled <i>event
1273: loop</i>.</p>
1.8 ihickson 1274:
1.81 ihickson 1275: </li>
1.8 ihickson 1276:
1277: <li>
1.71 ihickson 1278:
1.123 ihickson 1279: <p>Empty the <var title="">worker global scope</var>'s <span>list
1280: of active timeouts</span> and its <span>list of active
1281: intervals</span>.</p>
1.50 ihickson 1282:
1.81 ihickson 1283: </li>
1.50 ihickson 1284:
1.247 ihickson 1285: <li>
1286:
1287: <p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1288: ports</a>.</p>
1289:
1290: </li>
1291:
1.155 ihickson 1292: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1293: run the following steps in parallel with the worker's main loop (the
1.281 ihickson 1294: "<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 <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1295: true.</li>
1296:
1297:
1.115 ihickson 1298: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1299: queued in the <span>event loop</span>'s <span title="task
1.281 ihickson 1300: queue">task queues</span>, discard them without processing them.</li>
1301:
1.81 ihickson 1302:
1303: <li><p>Wait a user-agent-defined amount of time.</li>
1304:
1.281 ihickson 1305: <li><p>Abort the script currently running in the worker.</li>
1.81 ihickson 1306:
1.155 ihickson 1307: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1308: processing model on a worker at any time, e.g. in response to user
1309: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1310: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1311: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1312: 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 1313: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1314: "<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 1315: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1316: true.</li>
1317:
1.115 ihickson 1318: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1319: queued in the <span>event loop</span>'s <span title="task
1320: queue">task queues</span>, discard them without processing
1321: them.</li>
1322:
1323: <li><p>Abort the script currently running in the worker.</li>
1324:
1.115 ihickson 1325: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1326: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1327: worker is a dedicated worker), then empty the <span>port message
1328: queue</span> of the port that the worker's implicit port is
1329: entangled with.</li>
1330:
1.155 ihickson 1331: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.186 ihickson 1332: <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 1333: worker's scripts, if the error did not occur while handling a
1334: previous script error, the user agent must <span>report the
1335: 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 1336: attribute.
1337:
1.226 ihickson 1338: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1339:
1340: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1341: the error occurred while handling a previous script error, the error
1.215 ihickson 1342: may be reported to the user.
1.205 ihickson 1343:
1.226 ihickson 1344: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1345:
1346: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1347: the error occurred while handling a previous script error, the user
1.123 ihickson 1348: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1349: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1350: 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 1351: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1352: 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 1353: 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 1354: appropriately. The default action of this event depends on whether
1.115 ihickson 1355: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1356: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1357: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1358: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1.215 ihickson 1359: <em>that</em> worker. Otherwise, then the error may be reported
1.155 ihickson 1360: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1.233 ihickson 1361: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : <span>Event</span> {
1.147 ihickson 1362: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1363: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1364: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1365: 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 1366: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.190 ihickson 1367: method must initialize the event in a manner analogous to the
1368: 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 1369: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1370: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1371: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1372: attribute represents the line number where the error occurred in the
1.208 ihickson 1373: 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]
1374: interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1375: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1.172 ihickson 1376: };
1.177 ihickson 1377: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handlers</span> (and their
1378: corresponding <span title="event handler event type">event handler
1379: event types</span>) that must be supported, as IDL attributes, by
1380: 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 1381: <tbody><tr><td><dfn id="handler-abstractworker-onerror" title="handler-AbstractWorker-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.186 ihickson 1382: </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 1383: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1384: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1385:
1.281 ihickson 1386: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports); attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1387: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1388: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1389: algorithm to be run on the worker with with the object is
1.155 ihickson 1390: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1391: <code>MessagePort</code> associated with them. This port is part of
1392: a channel that is set up when the worker is created, but it is not
1393: exposed. This object must never be garbage collected before the
1.155 ihickson 1394: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1.281 ihickson 1395: 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> method on <code><a href="#worker">Worker</a></code> objects
1396: must act as if, when invoked, it
1.81 ihickson 1397: immediately invoked the method of the same name on the port, with
1.177 ihickson 1398: the same arguments, and returned the same return value.<p>The following are the <span>event handlers</span> (and their
1399: corresponding <span title="event handler event type">event handler
1400: event types</span>) that must be supported, as IDL attributes, by
1401: 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 1402: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1403: </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 1404: 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 1405: script</span>'s <span title="script's base URL">base URL</span>,
1406: when the method is invoked.</li>
1.9 ihickson 1407:
1.81 ihickson 1408: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1409: exception.</li>
1.9 ihickson 1410:
1.167 ihickson 1411: <li>
1412:
1413: <p>If the <span>origin</span> of the resulting <span>absolute
1414: URL</span> is not the <span title="same origin">same</span> as the
1.216 ihickson 1415: origin of the <span>entry script</span>, then throw a
1.182 ihickson 1416: <code>SECURITY_ERR</code> exception.</p>
1.167 ihickson 1417:
1418: <p class="note">Thus, scripts must be external files with the same
1.269 ihickson 1419: scheme as the original page: you can't load a script from a <span title="data protocol"><code title="">data:</code> URL</span> or
1420: <span title="javascript protocol"><code title="">javascript:</code> URL</span>, and an <code>http:</code>
1421: page couldn't start workers using scripts with <code>http:</code>
1422: URLs.</p>
1.167 ihickson 1423:
1424: </li>
1.9 ihickson 1425:
1.185 ihickson 1426: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1427: object. Let <var title="">worker global scope</var> be this new
1428: object.</li>
1.9 ihickson 1429:
1.115 ihickson 1430: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1431: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1432:
1.185 ihickson 1433: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1434: owned by the <span title="script's global object">global
1435: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1436: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1437: port</var>.</li>
1.9 ihickson 1438:
1.81 ihickson 1439: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1440:
1.185 ihickson 1441: <li><p><span>Create a new <code>MessagePort</code> object</span>
1442: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1443:
1.81 ihickson 1444: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1445:
1.81 ihickson 1446: <li><p><span>Entangle</span> <var title="">outside port</var> and
1447: <var title="">inside port</var>.</li>
1.50 ihickson 1448:
1.81 ihickson 1449: <li><p>Return <var title="">worker</var>, and run the following
1450: steps asynchronously.</li>
1.50 ihickson 1451:
1452:
1.126 ihickson 1453: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1454: queue</span>.</li>
1.50 ihickson 1455:
1456: <li>
1.51 ihickson 1457:
1.123 ihickson 1458: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1459: <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 1460: constructor.</p>
1461:
1462: </li>
1463:
1464: <li>
1465:
1466: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1467: <var title="">worker global scope</var>'s list of <span>the
1468: worker's <code>Document</code>s</span></a> the
1469: <code>Document</code> objects in <var title="">docs</var>.</p>
1470:
1471: </li>
1472:
1473: <li>
1474:
1.192 ihickson 1475: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1476: of the <span title="concept-script">script</span> that invoked the
1477: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1478: are creating a nested worker), add <var title="">worker global
1479: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 1480: <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 1481: constructor.</p>
1482:
1483: </li>
1484:
1485: <li>
1486:
1.115 ihickson 1487: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 1488: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 1489: script that invoked the method as the <var title="">owner browsing
1.232 ihickson 1490: context</var>, with the <span>script's document</span> of the
1491: script that invoked the method as the <var title="">owner
1492: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1493: script</span> as the <var title="">owner origin</var>, and with
1494: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1495:
1.81 ihickson 1496: </li>
1.4 ihickson 1497:
1.155 ihickson 1498: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1499: object</span> is either a <code>Window</code> object or an object
1.186 ihickson 1500: 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 1501: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1502: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1503: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1504: attribute must return the value it was assigned by the object's
1505: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1506: 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 1507: constructor is invoked, the user agent must run the following
1.155 ihickson 1508: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1509:
1510: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1511: exception.</li>
1512:
1.159 ihickson 1513: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1514: resulting <span>absolute URL</span>.</li>
1515:
1516: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1517: argument, or the empty string if the second argument was
1518: omitted.</li>
1.159 ihickson 1519:
1.167 ihickson 1520: <li>
1521:
1522: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1523: not the <span title="same origin">same</span> as the origin of the
1.216 ihickson 1524: <span>entry script</span>, then throw a <code>SECURITY_ERR</code>
1.182 ihickson 1525: exception.</p>
1.167 ihickson 1526:
1527: <p class="note">Thus, scripts must be external files with the same
1.269 ihickson 1528: scheme as the original page: you can't load a script from a <span title="data protocol"><code title="">data:</code> URL</span> or
1529: <span title="javascript protocol"><code title="">javascript:</code> URL</span>, and a <code>http:</code>
1530: page couldn't start workers using scripts with <code>http:</code>
1531: URLs.</p>
1.167 ihickson 1532:
1533: </li>
1.9 ihickson 1534:
1535: <li>
1536:
1.123 ihickson 1537: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1538: <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 1539: constructor.</p>
1540:
1541: </li>
1542:
1543: <li>
1544:
1.50 ihickson 1545: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1546:
1.155 ihickson 1547: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1548: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1549: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1550:
1.185 ihickson 1551: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1552: owned by the <span title="script's global object">global
1553: object</span> of the script that invoked the method. Let this be
1.123 ihickson 1554: the <var title="">outside port</var>.</li>
1.81 ihickson 1555:
1.115 ihickson 1556: <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 1557:
1.164 ihickson 1558: <li><p>Let <var title="">worker global scope</var> be
1559: null.</li>
1560:
1561: <li><p>If <var title="">name</var> is not the empty string and
1562: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1563: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1564: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1565: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1566: represents an <span>absolute URL</span> with the <span>same
1567: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1568: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1569:
1570: <li><p>Otherwise, if <var title="">name</var> is the empty string
1571: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1572: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1573: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.237 ihickson 1574: represents an <span>absolute URL</span> that is exactly equal to
1575: <var title="">scriptURL</var>, then let <var title="">worker
1576: global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1577: object.</li>
1.164 ihickson 1578:
1.9 ihickson 1579: <li>
1580:
1.164 ihickson 1581: <p>If <var title="">worker global scope</var> is not null, then
1582: run these steps:</p>
1.81 ihickson 1583:
1.164 ihickson 1584: <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 1585: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1586: exactly equal to <var title="">scriptURL</var>, then throw a
1587: <code>URL_MISMATCH_ERR</code> exception and abort all these
1588: steps.</li>
1.81 ihickson 1589:
1590: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1591:
1.185 ihickson 1592: <li><p><span>Create a new <code>MessagePort</code>
1593: object</span> owned by <var title="">worker global
1594: scope</var>. Let this be the <var title="">inside
1595: port</var>.</li>
1.81 ihickson 1596:
1597: <li><p><span>Entangle</span> <var title="">outside port</var>
1598: and <var title="">inside port</var>.</li>
1599:
1600: <li><p>Return <var title="">worker</var> and perform the next
1601: step asynchronously.</li>
1.9 ihickson 1602:
1.81 ihickson 1603: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1604: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1605: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1606: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1607: value is an array containing only the newly created port, and
1608: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1609:
1.123 ihickson 1610: <li>
1611:
1612: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1613: <var title="">worker global scope</var>'s list of <span>the
1614: worker's <code>Document</code>s</span></a> the
1615: <code>Document</code> objects in <var title="">docs</var>.</p>
1616:
1617: </li>
1618:
1.124 ihickson 1619: <li>
1620:
1.192 ihickson 1621: <p>If the <span title="script's global object">global
1622: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1623: that invoked the constructor is a
1624: <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
1625: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1626: object that is the <span title="script's global object">global
1627: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1628: that invoked the constructor.</p>
1629:
1630: </li>
1631:
1.81 ihickson 1632: <li><p>Abort all these steps.</li>
1.9 ihickson 1633:
1.155 ihickson 1634: </ol></li>
1.9 ihickson 1635:
1.185 ihickson 1636: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1637: object. Let <var title="">worker global scope</var> be this new
1638: object.</li>
1.9 ihickson 1639:
1.81 ihickson 1640: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1641:
1.115 ihickson 1642: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1643: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1644:
1.185 ihickson 1645: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.81 ihickson 1646: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1647:
1.81 ihickson 1648: <li><p><span>Entangle</span> <var title="">outside port</var> and
1649: <var title="">inside port</var>.</li>
1.9 ihickson 1650:
1.155 ihickson 1651: </ol></li>
1.28 ihickson 1652:
1.123 ihickson 1653: <li><p>Return <var title="">worker</var> and perform the remaining
1654: steps asynchronously.</li>
1.18 ihickson 1655:
1.81 ihickson 1656: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1657: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1658: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1659: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1660: is an array containing only the newly created port, and <span>queue
1661: a task</span> to dispatch the event at <var title="">worker global
1662: scope</var>.</li>
1.26 ihickson 1663:
1664: <li>
1.46 ihickson 1665:
1.123 ihickson 1666: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1667: <var title="">worker global scope</var>'s list of <span>the
1668: worker's <code>Document</code>s</span></a> the
1669: <code>Document</code> objects in <var title="">docs</var>.</p>
1670:
1671: </li>
1672:
1673: <li>
1674:
1.192 ihickson 1675: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1676: of the <span title="concept-script">script</span> that invoked the
1677: 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
1678: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1679: object that is the <span title="script's global object">global
1680: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1681: that invoked the constructor.</p>
1682:
1683: </li>
1684:
1685: <li>
1686:
1.159 ihickson 1687: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 1688: with the <span>script's browsing context</span> of the script that
1.159 ihickson 1689: invoked the method as the <var title="">owner browsing
1.232 ihickson 1690: context</var>, with the <span>script's document</span> of the
1691: script that invoked the method as the <var title="">owner
1692: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1693: script</span> as the <var title="">owner origin</var>, and with
1694: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1695:
1.60 ihickson 1696: </li>
1.81 ihickson 1697:
1.155 ihickson 1698: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1699: object</span> is either a <code>Window</code> object or an object
1.155 ihickson 1700: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1701: <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 1702: interface <dfn id="workerutils">WorkerUtils</dfn> {
1703: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.210 ihickson 1704: readonly attribute <a href="#workernavigator">WorkerNavigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 1705: };
1.184 ihickson 1706: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1707: objects, etc) are not available to workers in this version of this
1.155 ihickson 1708: 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 1709: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1710: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1711: anything. Abort these steps.</li>
1712:
1713: <li><p><span title="resolve a url">Resolve</span> each
1714: argument.</li>
1715:
1716: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1717: exception.</li>
1718:
1.26 ihickson 1719:
1720: <li>
1.81 ihickson 1721:
1.45 ihickson 1722: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 1723: resulting <span title="absolute URL">absolute URLs</span>, from
1.256 ihickson 1724: the <span>entry script</span>'s <span>origin</span>, with the
1.281 ihickson 1725: <i>synchronous flag</i> set.</p>
1.81 ihickson 1726: </li>
1.26 ihickson 1727:
1728: <li>
1729:
1.81 ihickson 1730: <p>For each argument in turn, in the order given, starting with
1731: the first one, run these substeps:</p>
1.26 ihickson 1732:
1.155 ihickson 1733: <ol><li>
1.26 ihickson 1734:
1.81 ihickson 1735: <p>Wait for the fetching attempt for the corresponding resource
1736: to complete.</p>
1.60 ihickson 1737:
1.81 ihickson 1738: <p>If the fetching attempt failed, throw a
1739: <code>NETWORK_ERR</code> exception and abort all these
1740: steps.</p>
1.45 ihickson 1741:
1.264 ihickson 1742: <p>If the attempt succeeds, then let <var title="">source</var> be
1743: the script resource <span>decoded as UTF-8, with error
1744: handling</span>.
1745:
1746: <a href="#refsHTML">[HTML]</a>
1747:
1748: </p>
1.85 ihickson 1749:
1750: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1751:
1.115 ihickson 1752: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1753: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1754: type.</p>
1.61 ihickson 1755:
1.81 ihickson 1756: </li>
1.26 ihickson 1757:
1.81 ihickson 1758: <li>
1.26 ihickson 1759:
1.81 ihickson 1760: <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 1761: same global object, browsing context, URL character encoding,
1762: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 1763: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1764:
1.115 ihickson 1765: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1766: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1767: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1768: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1769:
1.199 ihickson 1770: <p>If it failed to parse, then throw an ECMAScript
1771: <code>SyntaxError</code> exception and abort all these
1772: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 1773:
1.81 ihickson 1774: <p>If an exception was raised or if the script was prematurely
1775: aborted, then abort all these steps, letting the exception or
1776: aborting continue to be processed by the script that called the
1.115 ihickson 1777: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 1778: method.</p>
1779:
1.115 ihickson 1780: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 1781: worker</a>" algorithms abort the script then abort all these
1782: steps.</p>
1783:
1784: </li>
1785:
1.155 ihickson 1786: </ol></li>
1.152 ihickson 1787:
1.210 ihickson 1788: </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 1789: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1.210 ihickson 1790: the <code><a href="#workernavigator">WorkerNavigator</a></code> interface, which represents the
1791: identity and state of the user agent (the client):<pre class="idl">interface <dfn id="workernavigator">WorkerNavigator</dfn> {};
1792: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorID</span>;
1793: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorOnLine</span>;</pre><p>Objects implementing the <code><a href="#workernavigator">WorkerNavigator</a></code> interface
1794: also implement the <code>NavigatorID</code> and
1795: <code>NavigatorOnLine</code> interfaces.
1.205 ihickson 1796:
1.226 ihickson 1797: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1798:
1.210 ihickson 1799: <p>This <code><a href="#workernavigator">WorkerNavigator</a></code> interface must not exist if the
1800: interface's <span>relevant namespace object</span> is a
1.272 ihickson 1801: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h3 id="interface-objects-and-constructors"><span class="secno">5.3 </span>Interface objects and constructors</h3><p>There must be no interface objects and constructors available in
1.192 ihickson 1802: the global scope of scripts whose <span>script's global
1803: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 1804: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 1805: constructors defined by the XMLHttpRequest specifications, except
1806: that the <span>document response entity body</span> must always be
1.160 ihickson 1807: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
1808: <span>script's base URL</span>; the
1809: <span><code>XMLHttpRequest</code> origin</span> is the script's
1810: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 1811:
1.205 ihickson 1812: <li><p>The interface objects and constructors defined by this
1813: specification.</li>
1.119 ihickson 1814:
1.205 ihickson 1815: <li><p>Constructors defined by specifications that explicitly say
1816: that they should be visible when the <span>script's global
1817: object</span> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>, a
1818: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>, or an object implementing the
1819: <code><a href="#workerutils">WorkerUtils</a></code> interface; the interfaces of any objects
1820: with such constructors; and the interfaces of any objects made
1821: accessible through APIs exposed by those constructors or made
1822: accessible through interfaces to be implemented by any objects that
1823: are themselves accessible to scripts whose <span>script's global
1824: object</span> implements the <code><a href="#workerutils">WorkerUtils</a></code>
1825: interface.</li>
1826:
1827: </ul><p class="note">These requirements do not override the requirements
1828: defined by the Web IDL specification, in particular concerning the
1.272 ihickson 1829: visibility of interfaces annotated with the <code title="">[NoInterfaceObject]</code> extended attribute.<h3 id="worker-locations"><span class="secno">5.4 </span>Worker locations</h3><pre class="idl">interface <dfn id="workerlocation">WorkerLocation</dfn> {
1.263 ihickson 1830: // <span>URL decomposition IDL attributes</span>
1.115 ihickson 1831: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
1832: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
1833: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
1834: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
1835: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
1836: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
1837: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
1838: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 1839: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
1840: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 1841: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 1842: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 1843: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 1844: <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>,
1845: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
1846: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
1.263 ihickson 1847: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>.
1848: These must follow the rules given for <span>URL decomposition IDL
1849: attributes</span>, with the <span title="concept-uda-input">input</span> being the <span>absolute
1850: URL</span> that the object represents (same as the <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and the
1851: <span title="concept-uda-setter">common setter action</span> being a
1852: no-op, since the attributes are defined to be readonly.
1.205 ihickson 1853:
1.226 ihickson 1854: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1855:
1.209 ihickson 1856: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface must not exist if the
1857: interface's <span>relevant namespace object</span> is a
1.281 ihickson 1858: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h2 class="no-num" id="references">References</h2><p>All references are normative unless marked "Non-normative".</p><dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.276 ihickson 1859: <dd><cite><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html">Web DOM Core</a></cite>, A. van Kesteren. W3C.</dd>
1.153 ihickson 1860:
1.152 ihickson 1861: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
1.281 ihickson 1862: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
1.152 ihickson 1863: Object Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 1864: D. Schepers. W3C.</dd>
1.152 ihickson 1865:
1866: <dt id="refsECMA262">[ECMA262]</dt>
1867: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1.226 ihickson 1868: Language Specification</a></cite>. ECMA.</dd>
1.152 ihickson 1869:
1.226 ihickson 1870: <dt id="refsHTML">[HTML]</dt>
1871: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML</a></cite>,
1872: I. Hickson. WHATWG.</dd>
1.152 ihickson 1873:
1.154 ihickson 1874: <dt id="refsRFC2119">[RFC2119]</dt>
1.265 ihickson 1875: <dd><cite><a href="http://tools.ietf.org/html/rfc2119">Key words for use in
1.226 ihickson 1876: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF.</dd>
1.154 ihickson 1877:
1878: <dt id="refsWEBIDL">[WEBIDL]</dt>
1.281 ihickson 1879: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
1.226 ihickson 1880: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 1881:
1.152 ihickson 1882: <dt id="refsXHR">[XHR]</dt>
1.281 ihickson 1883: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.226 ihickson 1884: A. van Kesteren. W3C.</dd>
1.152 ihickson 1885:
1.221 ihickson 1886: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 1887:
1888: Aaron Boodman,
1.155 ihickson 1889: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 1890: Anne van Kesteren,
1891: Ben Turner,
1892: Dmitry Titov,
1.96 ihickson 1893: Drew Wilson,
1.97 ihickson 1894: Jeremy Orlow,
1.81 ihickson 1895: Jonas Sicking,
1896: Justin James,
1897: Kevin Hakanson,
1898: Maciej Stachowiak,
1899: Michael Nordman,
1900: Mike Smith,
1901:
1902: and
1903:
1904: Philip Taylor
1905:
1.155 ihickson 1906: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 1907: technology and whose experience has been a huge influence on this
1.155 ihickson 1908: specification.
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