Annotation of html5/workers/Overview.html, revision 1.156
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1.155 ihickson 166: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><!-- ZZZ ED vs WD --><div class="head">
1.115 ihickson 167: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
1.54 ihickson 168: <h1>Web Workers</h1>
1.109 ihickson 169: <!--ZZZ:-->
1.117 ihickson 170: <!--<h2 class="no-num no-toc">W3C Working Draft 23 April 2009</h2>-->
1.156 ! ihickson 171: <h2 class="no-num no-toc" id="editor-s-draft-date-1-january-1970">Editor's Draft 17 August 2009</h2>
1.109 ihickson 172: <!--:ZZZ-->
1.155 ihickson 173: <dl><!-- ZZZ: update the month/day (twice), (un)comment out
1.117 ihickson 174: <dt>This Version:</dt>
1.115 ihickson 175: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20090423/">http://www.w3.org/TR/2009/WD-workers-20090423/</a></dd>
1.155 ihickson 176: :ZZZ --><dt>Latest Published Version:</dt>
1.115 ihickson 177: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 178: <dt>Latest Editor's Draft:</dt>
1.115 ihickson 179: <dd><a href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 180: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 181: <dt>Previous Versions:</dt>
1.113 ihickson 182: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20090423/">http://www.w3.org/TR/2009/WD-workers-20090423/</a>
1.117 ihickson 183: <!-- :ZZZ -->
1.81 ihickson 184: <dt>Editors:</dt>
1.115 ihickson 185: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 186: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
187: © 2009 <a href="http://www.w3.org/"><abbr title="World Wide
188: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 189: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
190: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
191: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
192: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
193: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 194: use</a> rules apply.</p>
1.155 ihickson 195: </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 196: authors to spawn background workers running scripts in parallel to
197: their main page. This allows for thread-like operation with
1.155 ihickson 198: message-passing as the coordination mechanism.<h2 class="no-num no-toc" id="status-of-this-document">Status of this document</h2><!-- intro boilerplate (required) --><p><em>This section describes the status of this document at the
1.81 ihickson 199: time of its publication. Other documents may supersede this
200: document. A list of current W3C publications and the most recently
201: formally published revision of this technical report can be found in
1.115 ihickson 202: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.155 ihickson 203: at http://www.w3.org/TR/.</em></p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- XXX this section will be moved back to just below the copyright
1.116 ihickson 204: notice in the header by October 2009 unless the spec as a whole has
1.155 ihickson 205: been transitioned to a more permissive license by that time. --><!-- XXX when moving this text, add: class="alt copyright" --><p>The <a href="http://www.whatwg.org/specs/web-workers/current-work/">WHATWG
1.116 ihickson 206: version</a> of this specification is available under a license that
1.155 ihickson 207: permits reuse of the specification text.</p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- where to send feedback (required) --><p>If you wish to make comments regarding this document, please send
1.115 ihickson 208: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 209: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 210: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 211:
212: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 213: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
214: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 215: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 216:
1.155 ihickson 217: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 218: stable. <strong>Implementors who are not taking part in the
219: discussions are likely to find the specification changing out from
220: under them in incompatible ways.</strong> Vendors interested in
221: implementing this specification before it eventually reaches the
222: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 223: mailing lists and take part in the discussions.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- version history or list of changes (required) --><p>The latest stable version of the editor's draft of this
1.115 ihickson 224: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
225: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 226: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 227: unfinished text in the process of being prepared) is available <a href="http://www.whatwg.org/specs/web-workers/current-work/">on the
1.81 ihickson 228: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 229: following locations:</p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><ul><li>Twitter messages (non-editorial changes only): <a href="http://twitter.com/WHATWG">http://twitter.com/WHATWG</a></li>
1.115 ihickson 230: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
231: <li>Commit-Watchers mailing list: <a href="http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org">http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></li>
232: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
233: <li>CVS log: <a href="http://dev.w3.org/cvsweb/html5/workers/Overview.html">http://dev.w3.org/cvsweb/html5/workers/Overview.html</a></li>
1.155 ihickson 234: </ul><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- status of document, group responsible (required) --><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Apps
1.81 ihickson 235: Working Group</a> is the W3C working group responsible for this
236: specification's progress along the W3C Recommendation track.
237: <!--ZZZ:-->
1.117 ihickson 238: <!--This specification is the 23 April 2009 Working Draft.-->
1.156 ! ihickson 239: This specification is the 17 August 2009 Editor's Draft.
1.81 ihickson 240: <!--:ZZZ-->
1.155 ihickson 241: </p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- relationship to other work (required) --><p>This specification is also being produced by the <a href="http://www.whatwg.org/">WHATWG</a>. The two specifications are
242: identical from the table of contents onwards.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- context and rationale (required) --><p>This specification is intended to specify a part of the Web
1.81 ihickson 243: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 244: document primarily to ease the cognitive load on reviewers.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- required patent boilerplate --><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5
1.115 ihickson 245: 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 246: any patent disclosures</a> made in connection with the deliverables
247: of the group; that page also includes instructions for disclosing a
248: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 249: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
250: Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
1.155 ihickson 251: 6 of the W3C Patent Policy</a>.<h2 class="no-num no-toc" id="contents">Table of contents</h2>
1.81 ihickson 252: <!--begin-toc-->
1.115 ihickson 253: <ol class="toc">
254: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 255: <ol>
1.115 ihickson 256: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
257: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 258: <ol>
1.115 ihickson 259: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
260: <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>
261: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.3 </span>Worker used for background I/O</a></li>
262: <li><a href="#shared-workers"><span class="secno">1.2.4 </span>Shared workers</a></li>
263: <li><a href="#delegation"><span class="secno">1.2.5 </span>Delegation</a></li>
264: <li><a href="#providing-libraries"><span class="secno">1.2.6 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 265: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 266: <ol>
1.148 ihickson 267: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
268: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
269: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
270: <ol>
271: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 272: <ol>
1.148 ihickson 273: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
274: <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>
275: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> inteface</a></ol></li>
276: <li><a href="#base-urls-and-origins-of-workers"><span class="secno">4.2 </span>Base URLs and origins of workers</a></li>
277: <li><a href="#decoding-scripts"><span class="secno">4.3 </span>Decoding scripts</a></li>
278: <li><a href="#the-event-loop"><span class="secno">4.4 </span>The event loop</a></li>
279: <li><a href="#the-worker-s-lifetime"><span class="secno">4.5 </span>The worker's lifetime</a></li>
280: <li><a href="#processing-model"><span class="secno">4.6 </span>Processing model</a></li>
281: <li><a href="#runtime-script-errors"><span class="secno">4.7 </span>Runtime script errors</a></li>
282: <li><a href="#creating-workers"><span class="secno">4.8 </span>Creating workers</a>
1.81 ihickson 283: <ol>
1.148 ihickson 284: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.8.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
285: <li><a href="#dedicated-workers-and-the-worker-interface"><span class="secno">4.8.2 </span>Dedicated workers and the <code>Worker</code> interface</a></li>
286: <li><a href="#shared-workers-and-the-sharedworker-interface"><span class="secno">4.8.3 </span>Shared workers and the <code>SharedWorker</code> interface</a></ol></ol></li>
287: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 288: <ol>
1.148 ihickson 289: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
290: <li><a href="#the-navigator-object"><span class="secno">5.2 </span>The <code title="worker-Navigator">Navigator</code> object</a></li>
291: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
292: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
293: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 294: <li><a class="no-num" href="#references">References</a></li>
295: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 296: <!--end-toc--><hr><h2 id="introduction"><span class="secno">1 </span>Introduction</h2><h3 id="scope"><span class="secno">1.1 </span>Scope</h3><p><i>This section is non-normative.</i><p>This specification defines an API for running scripts in the
297: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 298: scripts that respond to clicks or other user interactions, and
299: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 300: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 301: relatively heavy-weight, and are not intended to be used in large
302: numbers. For example, it would be inappropriate to launch one worker
303: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 304: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
305: 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
306: 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
307: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
308: (naïvely) compute prime numbers, and progressively displays the
309: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 310: <html>
311: <head>
312: <title>Worker example: One-core computation</title>
313: </head>
314: <body>
315: <p>The highest prime number discovered so far is: <output id="result"></output></p>
316: <script>
1.50 ihickson 317: var worker = new Worker('worker.js');
318: worker.onmessage = function (event) {
1.54 ihickson 319: document.getElementById('result').textContent = event.data;
1.29 ihickson 320: };
1.81 ihickson 321: </script>
322: </body>
1.155 ihickson 323: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 324: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 325: representing that worker, which is used to communicate with the
1.115 ihickson 326: worker. That object's <code title="handler-Worker-onmessage"><a href="#handler-worker-onmessage">onmessage</a></code> event handler
1.155 ihickson 327: attribute allows the code to receive messages from the worker.<p>The worker itself is as follows:<pre>var n = 1;
1.29 ihickson 328: search: while (true) {
329: n += 1;
330: for (var i = 2; i <= Math.sqrt(n); i += 1)
331: if (n % i == 0)
332: continue search;
333: // found a prime!
1.50 ihickson 334: postMessage(n);
1.155 ihickson 335: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 336: number. To send a message back to the page, the <code title="dom-DedicatedWorkerGlobalScope-postMessage"><a href="#dom-dedicatedworkerglobalscope-postmessage">postMessage()</a></code>
1.155 ihickson 337: 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 338: task is to listen for notifications from the server, and, when
339: appropriate, either add or remove data from the client-side
1.155 ihickson 340: database.<p>Since no communication occurs between the worker and the main
341: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 342: new Worker('worker.js');
1.155 ihickson 343: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 344: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 345: server.onmessage = function (event) {
346: // data is in the format "command key value"
1.54 ihickson 347: var data = event.data.split(' ');
1.31 ihickson 348: switch (data[0]) {
349: case '+':
350: database.transaction(function(tx) {
351: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
352: });
353: case '-':
354: database.transaction(function(tx) {
355: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
356: });
357: }
1.155 ihickson 358: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 359: mechanism and opens the local database (which, we presume, has been
360: created earlier). The worker then just listens for messages from the
361: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 362: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 363: this example online</a>. (This example will not actually function,
364: since the server does not actually exist and the database is not
1.155 ihickson 365: 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 366: fetching stock updates for at regular intervals, and one for
1.155 ihickson 367: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 368: <html>
369: <head>
370: <title>Worker example: Stock ticker</title>
371: <script>
1.33 ihickson 372: // TICKER
373: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 374: var ticker = new Worker('ticker.js');
1.33 ihickson 375:
376: // SEARCHER
1.50 ihickson 377: var searcher = new Worker('searcher.js');
1.33 ihickson 378: function search(query) {
1.50 ihickson 379: searcher.postMessage(query);
1.33 ihickson 380: }
381:
382: // SYMBOL SELECTION UI
383: function select(newSymbol) {
384: symbol = newSymbol;
1.50 ihickson 385: ticker.postMessage(symbol);
1.33 ihickson 386: }
1.81 ihickson 387: </script>
388: </head>
1.122 ihickson 389: <body onload="search('')">
1.81 ihickson 390: <p><output id="symbol"></output> <output id="value"></output></p>
391: <script>
1.50 ihickson 392: ticker.onmessage = function (event) {
1.54 ihickson 393: var data = event.data.split(' ');
1.33 ihickson 394: document.getElementById('symbol').textContent = data[0];
395: document.getElementById('value').textContent = data[1];
396: };
1.50 ihickson 397: ticker.postMessage(symbol);
1.81 ihickson 398: </script>
1.122 ihickson 399: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 400: <ul id="results"></ul>
401: <script>
1.50 ihickson 402: searcher.onmessage = function (event) {
1.54 ihickson 403: var data = event.data.split(' ');
1.33 ihickson 404: var results = document.getElementById('results');
405: while (results.hasChildNodes()) // clear previous results
406: results.removeChild(results.firstChild);
407: for (var i = 0; i < data.length; i += 1) {
408: // add a list item with a button for each result
409: var li = document.createElement('li');
410: var button = document.createElement('button');
411: button.value = data[i];
412: button.type = 'button';
413: button.onclick = function () { select(this.value); };
414: button.textContent = data[i];
415: li.appendChild(button);
416: results.appendChild(li);
417: }
418: };
1.81 ihickson 419: </script>
420: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
421: </body>
1.155 ihickson 422: </html></pre><p>The two workers use a common library for performing the actual
423: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 424: try {
425: var xhr = new XMLHttpRequest();
426: xhr.open('GET', url, false);
427: xhr.send();
428: return xhr.responseText;
429: } catch (e) {
430: return ''; // turn all errors into empty results
431: }
1.155 ihickson 432: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 433: var timer;
434: var symbol;
435: function update() {
1.50 ihickson 436: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 437: timer = setTimeout(update, 10000);
438: }
1.50 ihickson 439: onmessage = function (event) {
1.33 ihickson 440: if (timer)
441: clearTimeout(timer);
1.54 ihickson 442: symbol = event.data;
1.33 ihickson 443: update();
1.155 ihickson 444: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 445: onmessage = function (event) {
1.54 ihickson 446: postMessage(get('search.cgi?' + event.data));
1.155 ihickson 447: };</pre><p><a href="http://www.whatwg.org/demos/workers/stocks/page.html">View this example online</a>.<h4 id="shared-workers"><span class="secno">1.2.4 </span>Shared workers</h4><p><i>This section is non-normative.</i><p>In this example, multiple windows (viewers) can be opened that
1.81 ihickson 448: are all viewing the same map. All the windows share the same map
449: information, with a single worker coordinating all the viewers. Each
450: viewer can move around independently, but if they set any data on
1.155 ihickson 451: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
452: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 453: <html>
454: <head>
455: <title>Workers example: Multiviewer</title>
456: <script>
1.36 ihickson 457: function openViewer() {
458: window.open('viewer.html');
459: }
1.81 ihickson 460: </script>
461: </head>
462: <body>
463: <p><button type=button onclick="openViewer()">Open a new
464: viewer</button></p>
465: <p>Each viewer opens in a new window. You can have as many viewers
466: as you like, they all view the same data.</p>
467: </body>
1.155 ihickson 468: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 469: <html>
470: <head>
471: <title>Workers example: Multiviewer viewer</title>
472: <script>
1.50 ihickson 473: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 474:
475: // CONFIGURATION
476: function configure(event) {
1.54 ihickson 477: if (event.data.substr(0, 4) != 'cfg ') return;
478: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 479: // update display to mention our name is name
480: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
481: // no longer need this listener
1.43 ihickson 482: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 483: }
1.53 ihickson 484: worker.port.addEventListener('message', configure, false);
1.36 ihickson 485:
486: // MAP
487: function paintMap(event) {
1.54 ihickson 488: if (event.data.substr(0, 4) != 'map ') return;
489: var data = event.data.substr(4).split(',');
1.36 ihickson 490: // display tiles data[0] .. data[8]
491: var canvas = document.getElementById('map');
492: var context = canvas.getContext('2d');
493: for (var y = 0; y < 3; y += 1) {
494: for (var x = 0; x < 3; x += 1) {
495: var tile = data[y * 3 + x];
496: if (tile == '0')
497: context.fillStyle = 'green';
498: else
499: context.fillStyle = 'maroon';
500: fillRect(x * 50, y * 50, 50, 50);
501: }
502: }
503: }
1.53 ihickson 504: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 505:
506: // PUBLIC CHAT
507: function updatePublicChat(event) {
1.54 ihickson 508: if (event.data.substr(0, 4) != 'txt ') return;
509: var name = event.data.substr(4).split(' ', 1);
510: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 511: // display "<name> message" in public chat
1.36 ihickson 512: var dialog = document.getElementById('public');
513: var dt = document.createElement('dt');
514: dt.textContent = name;
515: dialog.appendChild(dt);
516: var dd = document.createElement('dd');
517: dd.textContent = message;
518: dialog.appendChild(dd);
519: }
1.53 ihickson 520: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 521:
522: // PRIVATE CHAT
523: function startPrivateChat(event) {
1.54 ihickson 524: if (event.data.substr(0, 4) != 'msg ') return;
525: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 526: var port = event.ports[0];
1.36 ihickson 527: // display a private chat UI
528: var ul = document.getElementById('private');
529: var li = document.createElement('li');
530: var h3 = document.createElement('h3');
531: h3.textContent = 'Private chat with ' + name;
532: li.appendChild(h3);
533: var dialog = document.createElement('dialog');
534: var addMessage = function(name, message) {
535: var dt = document.createElement('dt');
536: dt.textContent = name;
537: dialog.appendChild(dt);
538: var dd = document.createElement('dd');
539: dd.textContent = message;
540: dialog.appendChild(dd);
541: };
542: port.onmessage = function (event) {
1.54 ihickson 543: addMessage(name, event.data);
1.36 ihickson 544: };
545: li.appendChild(dialog);
546: var form = document.createElement('form');
547: var p = document.createElement('p');
548: var input = document.createElement('input');
549: input.size = 50;
550: p.appendChild(input);
551: p.appendChild(document.createTextNode(' '));
552: var button = document.createElement('button');
553: button.textContent = 'Post';
554: p.appendChild(button);
555: form.onsubmit = function () {
556: port.postMessage(input.value);
557: addMessage('me', input.value);
558: input.value = '';
559: return false;
560: };
561: form.appendChild(p);
562: li.appendChild(form);
563: }
1.53 ihickson 564: worker.port.addEventListener('message', startPrivateChat, false);
1.81 ihickson 565: </script>
566: </head>
567: <body>
568: <h1>Viewer</h1>
569: <h2>Map</h2>
570: <p><canvas id="map" height=150 width=150></canvas></p>
571: <p>
572: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
573: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
574: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
575: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
576: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
577: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
578: </p>
579: <h2>Public Chat</h2>
580: <dialog id="public"></dialog>
581: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
582: <p>
583: <input type="text" name="message" size="50">
584: <button>Post</button>
585: </p>
586: </form>
587: <h2>Private Chat</h2>
588: <ul id="private"></ul>
589: </body>
590: </html>
1.155 ihickson 591: </pre><p>There are several key things worth noting about the way the
592: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 593: processing function, the code here attaches multiple event
594: listeners, each one performing a quick check to see if it is
595: relevant for the message. In this example it doesn't make much
596: difference, but if multiple authors wanted to collaborate using a
597: single port to communicate with a worker, it would allow for
598: independent code instead of changes having to all be made to a
1.155 ihickson 599: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 600: unregister specific listeners when you are done with them, as is
601: done with the <code title="">configure()</code> method in this
1.155 ihickson 602: example.<p>Finally, the worker:<pre>
603: var nextName = 0;
1.36 ihickson 604: function getNextName() {
605: // this could use more friendly names
606: // but for now just return a number
607: return nextName++;
608: }
609:
610: var map = [
611: [0, 0, 0, 0, 0, 0, 0],
612: [1, 1, 0, 1, 0, 1, 1],
613: [0, 1, 0, 1, 0, 0, 0],
614: [0, 1, 0, 1, 0, 1, 1],
615: [0, 0, 0, 1, 0, 0, 0],
616: [1, 0, 0, 1, 1, 1, 1],
617: [1, 1, 0, 1, 1, 0, 1],
618: ];
619:
620: function wrapX(x) {
621: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 622: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 623: return x;
624: }
625:
626: function wrapY(y) {
627: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 628: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 629: return y;
630: }
631:
1.50 ihickson 632: function sendMapData(callback) {
1.36 ihickson 633: var data = '';
634: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
635: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
636: if (data != '')
637: data += ',';
638: data += map[y][x];
639: }
640: }
1.50 ihickson 641: callback('map ' + data);
1.36 ihickson 642: }
643:
644: var viewers = {};
645: onconnect = function (event) {
1.84 ihickson 646: event.ports[0]._name = getNextName();
647: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
648: viewers[event.ports[0]._name] = event.port._data;
649: event.ports[0].postMessage('cfg ' + name);
650: event.ports[0].onmessage = getMessage;
651: sendMapData(event.ports[0].postMessage);
1.36 ihickson 652: };
653:
654: function getMessage(event) {
1.54 ihickson 655: switch (event.data.substr(0, 4)) {
1.36 ihickson 656: case 'mov ':
1.54 ihickson 657: var direction = event.data.substr(4);
1.36 ihickson 658: var dx = 0;
659: var dy = 0;
660: switch (direction) {
661: case 'up': dy = -1; break;
662: case 'down': dy = 1; break;
663: case 'left': dx = -1; break;
664: case 'right': dx = 1; break;
665: }
666: event.target._data.x = wrapX(event.target._data.x + dx);
667: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 668: sendMapData(event.target.postMessage);
1.36 ihickson 669: break;
670: case 'set ':
1.54 ihickson 671: var value = event.data.substr(4);
1.36 ihickson 672: map[event.target._data.y][event.target._data.x] = value;
673: for (var viewer in viewers)
1.50 ihickson 674: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 675: break;
676: case 'txt ':
677: var name = event.target._name;
1.54 ihickson 678: var message = event.data.substr(4);
1.36 ihickson 679: for (var viewer in viewers)
680: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
681: break;
682: case 'msg ':
683: var party1 = event._data;
1.54 ihickson 684: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 685: if (party2) {
686: var channel = new MessageChannel();
1.84 ihickson 687: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
688: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 689: }
690: break;
691: }
1.155 ihickson 692: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 693: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 694: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 695: "msg" message from one viewer naming another viewer, it sets up a
696: direct connection between the two, so that the two viewers can
697: communicate directly without the worker having to proxy all the
1.155 ihickson 698: messages.<p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View this example online</a>.<h4 id="delegation"><span class="secno">1.2.5 </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 699: performance is to split computationally expensive tasks amongst
700: multiple workers. In this example, a computationally expensive task
701: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 702: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 703: <html>
704: <head>
705: <title>Worker example: One-core computation</title>
706: </head>
707: <body>
708: <p>The highest prime number discovered so far is: <output id="result"></output></p>
709: <script>
1.50 ihickson 710: var worker = new Worker('worker.js');
711: worker.onmessage = function (event) {
1.54 ihickson 712: document.getElementById('result').textContent = event.data;
1.40 ihickson 713: };
1.81 ihickson 714: </script>
715: </body>
1.155 ihickson 716: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 717: var num_workers = 10;
718: var items_per_worker = 1000000;
719:
720: // start the workers
721: var result = 0;
722: var pending_workers = num_workers;
723: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 724: var worker = new Worker('core.js');
725: worker.postMessage(i * items_per_worker);
726: worker.postMessage((i+1) * items_per_worker);
727: worker.onmessage = storeResult;
1.40 ihickson 728: }
729:
730: // handle the results
731: function storeResult(event) {
1.54 ihickson 732: result += 1*event.data;
1.40 ihickson 733: pending_workers -= 1;
734: if (pending_workers <= 0)
1.50 ihickson 735: postMessage(result); // finished!
1.155 ihickson 736: }</pre><p>It consists of a loop to start the subworkers, and then a handler
737: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 738: onmessage = getStart;
1.40 ihickson 739: function getStart(event) {
1.54 ihickson 740: start = 1*event.data;
1.40 ihickson 741: onmessage = getEnd;
742: }
743:
744: var end;
745: function getEnd(event) {
1.54 ihickson 746: end = 1*event.data;
1.40 ihickson 747: onmessage = null;
1.66 ihickson 748: work();
1.40 ihickson 749: }
750:
1.66 ihickson 751: function work() {
1.40 ihickson 752: var result = 0;
753: for (var i = start; i < end; i += 1) {
754: // perform some complex calculation here
755: result += 1;
756: }
1.50 ihickson 757: postMessage(result);
758: close();
1.155 ihickson 759: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 760: for the range of numbers thus specified, and then report the result
1.155 ihickson 761: back to the parent.<p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.<h4 id="providing-libraries"><span class="secno">1.2.6 </span>Providing libraries</h4><p><i>This section is non-normative.</i><p>Suppose that a cryptography library is made available that
762: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 763:
764: <dd>Takes a port, on which it will send two messages, first the
765: public key and then the private key.</dd>
766:
767: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
768:
769: <dd>Takes a port, to which any number of messages can be sent, the
770: first giving the public key, and the remainder giving the
771: plaintext, each of which is encrypted and then sent on that same
772: channel as the cyphertext. The user can close the port when it is
773: done encrypting content.</dd>
774:
775: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
776:
777: <dd>Takes a port, to which any number of messages can be sent, the
778: first giving the private key, and the remainder giving the
779: cyphertext, each of which is decrypted and then sent on that same
780: channel as the plaintext. The user can close the port when it is
781: done decrypting content.</dd>
1.49 ihickson 782:
1.155 ihickson 783: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 784: if (e.data == "genkeys")
1.84 ihickson 785: genkeys(e.ports[0]);
1.54 ihickson 786: else if (e.data == "encrypt")
1.84 ihickson 787: encrypt(e.ports[0]);
1.54 ihickson 788: else if (e.data == "decrypt")
1.84 ihickson 789: decrypt(e.ports[0]);
1.49 ihickson 790: }
791:
792: function genkeys(p) {
793: var keys = _generateKeyPair();
794: p.postMessage(keys[0]);
795: p.postMessage(keys[1]);
796: }
797:
798: function encrypt(p) {
799: var key, state = 0;
800: p.onmessage = function (e) {
801: if (state == 0) {
1.54 ihickson 802: key = e.data;
1.49 ihickson 803: state = 1;
804: } else {
1.54 ihickson 805: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 806: }
807: };
808: }
809:
810: function decrypt(p) {
811: var key, state = 0;
812: p.onmessage = function (e) {
813: if (state == 0) {
1.54 ihickson 814: key = e.data;
1.49 ihickson 815: state = 1;
816: } else {
1.54 ihickson 817: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 818: }
819: };
820: }
821:
1.50 ihickson 822: // support being used as a shared worker as well as a dedicated worker
823: if (this.onmessage) // dedicated worker
824: onmessage = handleMessage;
825: else // shared worker
826: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 827:
828:
829: // the "crypto" functions:
830:
831: function _generateKeyPair() {
832: return [Math.random(), Math.random()];
833: }
834:
835: function _encrypt(k, s) {
836: return 'encrypted-' + k + ' ' + s;
837: }
838:
839: function _decrypt(k, s) {
840: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 841: }</pre><p>Note that the crypto functions here are just stubs and don't do
842: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 843: <html>
844: <head>
845: <title>Worker example: Crypto library</title>
846: <script>
1.50 ihickson 847: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 848: function getKeys() {
849: var state = 0;
1.50 ihickson 850: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 851: if (state == 0)
1.54 ihickson 852: document.getElementById('public').value = e.data;
1.49 ihickson 853: else if (state == 1)
1.54 ihickson 854: document.getElementById('private').value = e.data;
1.49 ihickson 855: state += 1;
856: };
857: }
858: function enc() {
1.50 ihickson 859: var port = cryptoLib.startConversation("encrypt");
860: port.postMessage(document.getElementById('public').value);
861: port.postMessage(document.getElementById('input').value);
862: port.onmessage = function (e) {
1.54 ihickson 863: document.getElementById('input').value = e.data;
1.50 ihickson 864: port.close();
1.49 ihickson 865: };
866: }
867: function dec() {
1.50 ihickson 868: var port = cryptoLib.startConversation("decrypt");
869: port.postMessage(document.getElementById('private').value);
870: port.postMessage(document.getElementById('input').value);
871: port.onmessage = function (e) {
1.54 ihickson 872: document.getElementById('input').value = e.data;
1.50 ihickson 873: port.close();
1.49 ihickson 874: };
875: }
1.81 ihickson 876: </script>
877: <style>
1.49 ihickson 878: textarea { display: block; }
1.81 ihickson 879: </style>
880: </head>
881: <body onload="getKeys()">
882: <fieldset>
883: <legend>Keys</legend>
884: <p><label>Public Key: <textarea id="public"></textarea></label></p>
885: <p><label>Private Key: <textarea id="private"></textarea></label></p>
886: </fieldset>
887: <p><label>Input: <textarea id="input"></textarea></label></p>
888: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
889: </body>
1.155 ihickson 890: </html></pre><p>A later version of the API, though, might want to offload all the
891: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 892: if (e.data == "genkeys")
1.84 ihickson 893: genkeys(e.ports[0]);
1.54 ihickson 894: else if (e.data == "encrypt")
1.84 ihickson 895: encrypt(e.ports[0]);
1.54 ihickson 896: else if (e.data == "decrypt")
1.84 ihickson 897: decrypt(e.ports[0]);
1.49 ihickson 898: }
899:
900: function genkeys(p) {
1.50 ihickson 901: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 902: generator.postMessage('', [p]);
1.49 ihickson 903: }
904:
905: function encrypt(p) {
906: p.onmessage = function (e) {
1.54 ihickson 907: var key = e.data;
1.50 ihickson 908: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 909: encryptor.postMessage(key, [p]);
1.49 ihickson 910: };
911: }
912:
913: function encrypt(p) {
914: p.onmessage = function (e) {
1.54 ihickson 915: var key = e.data;
1.50 ihickson 916: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 917: decryptor.postMessage(key, [p]);
1.49 ihickson 918: };
919: }
920:
1.50 ihickson 921: // support being used as a shared worker as well as a dedicated worker
922: if (this.onmessage) // dedicated worker
923: onmessage = handleMessage;
924: else // shared worker
1.84 ihickson 925: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 926: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 927: var k = _generateKeyPair();
1.84 ihickson 928: e.ports[0].postMessage(k[0]);
929: e.ports[0].postMessage(k[1]);
1.49 ihickson 930: close();
931: }
1.50 ihickson 932:
933: function _generateKeyPair() {
934: return [Math.random(), Math.random()];
1.155 ihickson 935: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 936: var key = e.data;
1.84 ihickson 937: e.ports[0].onmessage = function (e) {
1.54 ihickson 938: var s = e.data;
1.50 ihickson 939: postMessage(_encrypt(key, s));
1.49 ihickson 940: }
1.50 ihickson 941: }
942:
943: function _encrypt(k, s) {
944: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 945: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 946: var key = e.data;
1.84 ihickson 947: e.ports[0].onmessage = function (e) {
1.54 ihickson 948: var s = e.data;
1.50 ihickson 949: postMessage(_decrypt(key, s));
1.49 ihickson 950: }
1.50 ihickson 951: }
952:
953: function _decrypt(k, s) {
954: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 955: }</pre><p>Notice how the users of the API don't have to even know that this
956: is happening — the API hasn't changed; the library can
1.81 ihickson 957: delegate to subworkers without changing its API, even though it is
1.155 ihickson 958: accepting data using message channels.<p><a href="http://www.whatwg.org/demos/workers/crypto/page.html">View this example online</a>.<h2 id="conformance-requirements"><span class="secno">2 </span>Conformance requirements</h2><p>All diagrams, examples, and notes in this specification are
1.81 ihickson 959: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 960: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 961: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
962: "OPTIONAL" in the normative parts of this document are to be
963: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 964: 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 965: (such as "strip any leading space characters" or "return false and
966: abort these steps") are to be interpreted with the meaning of the
967: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 968: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 969: attributes, methods or objects. Such requirements are to be
1.155 ihickson 970: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 971: may be implemented in any manner, so long as the end result is
972: equivalent. (In particular, the algorithms defined in this
973: specification are intended to be easy to follow, and not intended to
1.155 ihickson 974: be performant.)<p>The only conformance class defined by this specification is user
975: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 976: otherwise unconstrained inputs, e.g. to prevent denial of service
977: attacks, to guard against running out of memory, or to work around
1.155 ihickson 978: platform-specific limitations.<h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3><p>This specification relies on several other underlying
979: specifications.<dl><dt>HTML5</dt>
1.49 ihickson 980:
1.81 ihickson 981: <dd>
1.49 ihickson 982:
1.81 ihickson 983: <p>Many fundamental concepts from HTML5 are used by this
1.152 ihickson 984: specification. <a href="#refsHTML5">[HTML5]</a></p>
1.49 ihickson 985:
1.81 ihickson 986: </dd>
1.1 ihickson 987:
1.81 ihickson 988: <dt>WebIDL</dt>
1.1 ihickson 989:
990: <dd>
991:
1.81 ihickson 992: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 993: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 994:
1.81 ihickson 995: </dd>
1.1 ihickson 996:
1.155 ihickson 997: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 998: <code title="">Foo</code> is actually an interface, is sometimes
999: used instead of the more accurate "an object implementing the
1.155 ihickson 1000: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1001: scripts in Web applications, and does not necessarily imply the
1002: existence of an actual <code>Document</code> object or of any other
1003: <code>Node</code> objects as defined in the DOM Core
1.155 ihickson 1004: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>A DOM attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1005: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1006: <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 1007: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1008: 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 1009: workers. Dedicated workers, once created, and are linked to their
1010: creator; but message ports can be used to communicate from a
1011: dedicated worker to multiple other browsing contexts or
1012: workers. Shared workers, on the other hand, are named, and once
1013: created any script running in the same <span>origin</span> can
1.155 ihickson 1014: 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 1015: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1016: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1017:
1018: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1019: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1020: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1021: };
1.155 ihickson 1022: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;</pre><p>Objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface
1023: must also implement the <code>EventTarget</code> interface.<p>The <dfn id="dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self"><code>self</code></dfn> attribute
1024: 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 1025: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1026: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1027: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1028: 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 1029: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1030: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1031: have been added to the <span>event loop</span>'s <span title="task
1032: queue">task queues</span>.</p>
1033:
1034: <!-- v2-onclose
1035: <li><p><span>Queue a task</span> to <span>fire a simple
1.115 ihickson 1036: event</span> called <code title="event-close">close</code> at the
1.123 ihickson 1037: <code>WorkerGlobalScope</code> object.</p></li>
1038: -->
1.81 ihickson 1039:
1.115 ihickson 1040: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1041: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1042: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1043:
1.124 ihickson 1044: <li><p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1.123 ihickson 1045: ports</a>.</li>
1.81 ihickson 1046:
1.155 ihickson 1047: </ol><p>The following are the <span>event handler attributes</span> (and their corresponding <span title="event handler event type">event handler event types</span>)
1.102 ihickson 1048: that must be supported, as DOM attributes, by objects implementing
1.155 ihickson 1049: the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface:<table><thead><tr><th><span title="event handler attributes">event handler attribute</span> <th><span>Event handler event type</span>
1050: <tbody><!-- v2-onclose <tr><td><dfn title="handler-WorkerGlobalScope-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> --><tr><td><dfn id="handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1051: </table><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 1052: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1053: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, optional in <span>MessagePortArray</span> ports);<!--
1.77 ihickson 1054: <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1055: attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1056: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1057: had an implicit <code>MessagePort</code> associated with them. This
1058: port is part of a channel that is set up when the worker is created,
1059: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1060: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1061: at the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>The <dfn id="dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage"><code>postMessage()</code></dfn><!--
1.64 ihickson 1062: and <dfn
1063: title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
1.81 ihickson 1064: method<!--s (startConversation)--> on
1.115 ihickson 1065: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.81 ihickson 1066: invoked, it<!--/they (startConversation)--> immediately invoked the
1067: method of the same name on the port, with the same arguments, and
1.155 ihickson 1068: returned the same return value.<p>The following are the <span>event handler attributes</span> (and
1.123 ihickson 1069: their corresponding <span title="event handler event type">event
1070: handler event types</span>) that must be supported, as DOM
1071: attributes, by objects implementing the
1.155 ihickson 1072: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> interface:<table><thead><tr><th><span title="event handler attributes">event handler attribute</span> <th><span>Event handler event type</span>
1073: <tbody><tr><td><dfn id="handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1074: </table><p>For the purposes of the <span>offline application cache</span>
1.101 ihickson 1075: networking model, a dedicated worker is an extension of the
1.155 ihickson 1076: <span>cache host</span> from which it was created.<h4 id="shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> inteface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1077: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1078: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1079: readonly attribute <span>ApplicationCache</span> <a href="#dom-sharedworkerglobalscope-applicationcache" title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</a>;
1.144 ihickson 1080: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1081: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1082: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1083: attribute must return the value it was assigned when the
1.115 ihickson 1084: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1085: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1086: that can be used to obtain a reference to the worker using the
1.155 ihickson 1087: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handler attributes</span> (and
1.123 ihickson 1088: their corresponding <span title="event handler event type">event
1089: handler event types</span>) that must be supported, as DOM
1090: attributes, by objects implementing the
1.155 ihickson 1091: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> interface:<table><thead><tr><th><span title="event handler attributes">event handler attribute</span> <th><span>Event handler event type</span>
1092: <tbody><tr><td><dfn id="handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect"><code>onconnect</code></dfn> <td> <code title="event-connect">connect</code>
1093: </table><p>For the purposes of the <span>offline application cache</span>
1.101 ihickson 1094: networking model, a shared worker is its own <span>cache
1.115 ihickson 1095: host</span>. The <a href="#run-a-worker">run a worker</a> algorithm takes care of
1.155 ihickson 1096: associating the worker with an <span>application cache</span>.<p class="note">The <dfn id="dom-sharedworkerglobalscope-applicationcache" title="dom-SharedWorkerGlobalScope-applicationCache"><code>applicationCache</code></dfn>
1.123 ihickson 1097: attribute returns the <code>ApplicationCache</code> object for the
1.101 ihickson 1098: worker.</p><!-- normative conf criteria is in the appcache section
1.155 ihickson 1099: --><h3 id="base-urls-and-origins-of-workers"><span class="secno">4.2 </span>Base URLs and origins of workers</h3><p>Both the <span>origin</span> and <span>effective script
1.81 ihickson 1100: origin</span> of scripts running in workers are the
1101: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1102: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.155 ihickson 1103: represents.<h3 id="decoding-scripts"><span class="secno">4.3 </span>Decoding scripts</h3><p>When a user agent is to <dfn id="decode-a-script-resource">decode a script resource</dfn> to
1104: obtain its source in Unicode, it must run the following steps:<ol><li>
1.85 ihickson 1105:
1106: <p>Let <var title="">character encoding</var> be <i title="">unknown</i>.</p>
1107:
1108: </li>
1109:
1110: <li>
1111:
1112: <p>For each of the rows in the following table, starting with the
1113: first one and going down, if the resource has as many or more
1114: bytes available than the number of bytes in the first column, and
1115: the first bytes of the resource match the bytes given in the first
1116: column, then let <var title="">character encoding</var> be the
1117: encoding given in the cell in the second column of that row:</p>
1118:
1119: <!-- this table is present in several forms in this file; keep them in sync -->
1.155 ihickson 1120: <table><thead><tr><th>Bytes in Hexadecimal
1.85 ihickson 1121: <th>Encoding
1.155 ihickson 1122: <tbody><!-- nobody uses this
1.85 ihickson 1123: <tr>
1124: <td>00 00 FE FF
1125: <td>UTF-32BE
1126: <tr>
1127: <td>FF FE 00 00
1128: <td>UTF-32LE
1.155 ihickson 1129: --><tr><td>FE FF
1.85 ihickson 1130: <td>UTF-16BE
1.155 ihickson 1131: <tr><td>FF FE
1.85 ihickson 1132: <td>UTF-16LE
1.155 ihickson 1133: <tr><td>EF BB BF
1.85 ihickson 1134: <td>UTF-8
1135: <!-- nobody uses this
1136: <tr>
1137: <td>DD 73 66 73
1138: <td>UTF-EBCDIC
1139: -->
1.155 ihickson 1140: </table><p class="note">This step looks for Unicode Byte Order Marks
1.85 ihickson 1141: (BOMs).</p>
1142:
1143: </li>
1144:
1145: <li>
1146:
1147: <p>If <var title="">character encoding</var> is still <i title="">unknown</i>, apply the <span>algorithm for extracting an
1.115 ihickson 1148: encoding from a Content-Type</span> to the resource's <span title="Content-Type">Content Type metadata</span>; if this returns
1.85 ihickson 1149: an encoding, and the user agent supports that encoding, then let
1150: <var title="">character encoding</var> be that encoding.</p>
1151:
1152: </li>
1153:
1154: <li>
1155:
1156: <p>If <var title="">character encoding</var> is still <i title="">unknown</i>, then let <var title="">character
1157: encoding</var> be UTF-8.</p>
1158:
1159: </li>
1160:
1161: <li>
1162:
1163: <p>Convert the resource to Unicode using the character encoding
1164: given by <var title="">character encoding</var>.</p>
1165:
1166: <p>Return the text that is so obtained.</p>
1167:
1168: </li>
1169:
1.155 ihickson 1170: </ol><h3 id="the-event-loop"><span class="secno">4.4 </span>The event loop</h3><p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object has an <span>event
1.128 ihickson 1171: loop</span> distinct from those defined for <span title="unit of
1172: related similar-origin browsing contexts">units of related
1173: similar-origin browsing contexts</span>. This <span>event
1174: loop</span> has no associated <span>browsing context</span>, and its
1175: <span title="task queue">task queues</span> only have events,
1176: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1177: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1178: <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 1179: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1180: 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 1181: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1182: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.81 ihickson 1183: already on the queue are unaffected unless otherwise
1.115 ihickson 1184: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1185: timers stop firing, notifications for all pending asynchronous
1.155 ihickson 1186: operations are dropped, etc.<h3 id="the-worker-s-lifetime"><span class="secno">4.5 </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
1187: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1188: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1189: consists of all the <code>MessagePort</code> objects that are
1190: entangled with another port and that have one (but only one) port
1191: owned by <var title="">worker global scope</var>. This list includes
1192: <!--all the <code>MessagePort</code> objects that are in events
1.68 ihickson 1193: pending in the <span>event loop</span>, as well as (commented out
1194: because in practice it makes no difference either way as far as I
1195: can tell, and it would be hard to strictly implement since these
1.81 ihickson 1196: ports might not yet be across the thread boundary)--> the implicit
1.155 ihickson 1197: <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 1198: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1199: 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 1200: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1201: 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 1202: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1203: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1204: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1205: <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 1206: documents">add <var title="">d</var> to <var title="">q</var>'s
1207: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.155 ihickson 1208: <code>Document</code>s</span></a>.</p><!-- suggestions welcome
1209: on making this sentence into understandable English --><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1210: Document">discarded</span>, it must be removed from the list of
1211: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.155 ihickson 1212: whose list contains that <code>Document</code>.<p>Given a <span>script's global scope</span> <var title="">o</var>
1.123 ihickson 1213: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1214: <code>Document</code> objects to add</dfn> depends on the type of
1215: <var title="">o</var>. If <var title="">o</var> is a
1216: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1217: nested worker), then the relevant <code>Document</code>s are the
1218: <code>Document</code>s that are in <var title="">o</var>'s own list
1219: 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
1220: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1221: <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 1222: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1223: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1224: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1225: timers, database transactions, or network connections, or its list
1.124 ihickson 1226: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1227: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1228: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1229: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1230: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1231: <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 1232: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.155 ihickson 1233: <a href="#permissible-worker">permissible worker</a>.<h3 id="processing-model"><span class="secno">4.6 </span>Processing model</h3><p>When a user agent is to <dfn id="run-a-worker">run a worker</dfn> for a script with
1.81 ihickson 1234: <span>URL</span> <var title="">url</var>, a browsing context <var title="">owner browsing context</var>, and with global scope <var title="">worker global scope</var>, it must run the following
1.155 ihickson 1235: steps:<ol><li>
1.81 ihickson 1236:
1237: <p>Create a completely separate and parallel execution environment
1238: (i.e. a separate thread or process or equivalent construct), and
1.106 ihickson 1239: run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1240:
1241: </li>
1.4 ihickson 1242:
1.101 ihickson 1243: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1244: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1245: shared worker), and there are any <span title="relevant application
1246: cache">relevant application caches</span> that are identified by a
1247: 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 1248: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1249: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1250: cache</span> of those that match.</li>
1251:
1.4 ihickson 1252: <li>
1.52 ihickson 1253:
1.81 ihickson 1254: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>.</p>
1255:
1.129 ihickson 1256: <p>If the attempt fails, or if the attempt involves any redirects
1257: to URIs that do not have the <span>same origin</span> as <var title="">url</var> (even if the final URI is at the <span>same
1258: origin</span> as the original <var title="">url</var>), then for
1259: each <code><a href="#worker">Worker</a></code> or <code><a href="#sharedworker">SharedWorker</a></code> object
1260: associated with <var title="">worker global scope</var>,
1261: <span>queue a task</span> to <span>fire a simple event</span>
1262: called <code title="event-error">error</code> at that
1263: object. Abort these steps.</p>
1.7 ihickson 1264:
1.115 ihickson 1265: <p>If the attempt succeeds, then <a href="#decode-a-script-resource" title="decode a script
1.85 ihickson 1266: resource">decode the script resource</a> to obtain its <var title="">source</var>.</p>
1.81 ihickson 1267:
1.68 ihickson 1268: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1269:
1.115 ihickson 1270: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1271: type of the script is ignored. Unlike with <code>script</code>
1272: elements, there is no way to override the type. It's always
1273: assumed to be JavaScript.</p> <!-- XXX people will complain about
1.7 ihickson 1274: this. I guess we might want to examine the MIME type... -->
1.81 ihickson 1275:
1276: </li>
1.7 ihickson 1277:
1278: <li>
1.68 ihickson 1279:
1.115 ihickson 1280: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1281: created, as follows.</p>
1282:
1283: <p>Create a new <span>script execution environment</span>
1284: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1285:
1.68 ihickson 1286: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1287: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1288: entry-points</span>; set the <i>initial code entry-point</i> to
1289: the entry-point for any executable code to be immediately run.</p>
1290:
1291: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1292:
1293: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1294:
1.83 ihickson 1295: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1296: UTF-8. (This is just used for encoding non-ASCII characters in the
1297: query component of URLs.)</p>
1.68 ihickson 1298:
1299: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1300:
1.81 ihickson 1301: </li>
1.4 ihickson 1302:
1303: <li>
1.81 ihickson 1304:
1305: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1306: worker such that no sooner than it stops being either a
1307: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1308: worker</a>, and no later than it stops being a
1309: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1310: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1311: to true<!-- v2-onclose and <span title="queue a task">a task is
1312: queued</span> to <span>fire a simple event</span> called <code
1313: title="event-close">close</code> at <var title="">worker global
1314: scope</var>-->.</p>
1.81 ihickson 1315:
1316: </li>
1.9 ihickson 1317:
1318: <li>
1.7 ihickson 1319:
1.81 ihickson 1320: <p><strong>Suspending workers</strong>: Start monitoring the
1321: worker, such that whenever <var title="">worker global
1.115 ihickson 1322: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1323: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1324: agent suspends execution of script in that worker until such time
1.115 ihickson 1325: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1326: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1327: worker</a>.</p>
1.4 ihickson 1328:
1.81 ihickson 1329: </li>
1.68 ihickson 1330:
1331: <li>
1.4 ihickson 1332:
1.81 ihickson 1333: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1334: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1335: entry-point</i>, and let that run until it either returns, fails
1336: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1337: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1338: algorithms defined below.</p>
1339:
1.149 ihickson 1340: <!-- v2-onclose
1341: <p class="note">If the script gets aborted by the "<span>kill a
1342: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1343: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1344: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1345: for the <code title="message-close">close</code> event. The
1.149 ihickson 1346: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1347: events.</p>
1.149 ihickson 1348: -->
1.4 ihickson 1349:
1.81 ihickson 1350: </li>
1.4 ihickson 1351:
1.95 ihickson 1352: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1353: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1354: a dedicated worker), then enable the <span>port message
1355: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1356:
1.4 ihickson 1357: <li>
1.68 ihickson 1358:
1.115 ihickson 1359: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1360: 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 1361: to true.</p>
1.43 ihickson 1362:
1.81 ihickson 1363: </li>
1.4 ihickson 1364:
1365: <li>
1366:
1.81 ihickson 1367: <p>Run the oldest task on one of the <span>event loop</span>'s
1368: <span title="task queue">task queues</span>, if any. The user
1369: agent may pick any <span>task queue</span>.</p>
1370:
1.115 ihickson 1371: <p class="note">The handling of events or the execution of
1372: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1373: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1374: defined below.</p>
1.8 ihickson 1375:
1.81 ihickson 1376: </li>
1.4 ihickson 1377:
1378: <li>
1379:
1.81 ihickson 1380: <p>Remove the task run in the previous step, if any, from its
1381: <span>task queue</span>.</p>
1.4 ihickson 1382:
1.81 ihickson 1383: </li>
1.4 ihickson 1384:
1385: <li>
1.8 ihickson 1386:
1.81 ihickson 1387: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1388: <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 1389: to false, then jump back to the step above labeled <i>event
1390: loop</i>.</p>
1.8 ihickson 1391:
1.81 ihickson 1392: </li>
1.8 ihickson 1393:
1394: <li>
1.71 ihickson 1395:
1.123 ihickson 1396: <p>If there are any outstanding transactions that have callbacks
1397: that involve <span title="concept-script">scripts</span> whose
1398: <span title="script's global object">global object</span> is the
1399: <var title="">worker global scope</var>, roll them back (without
1400: invoking any of the callbacks).</p>
1.50 ihickson 1401:
1.123 ihickson 1402: </li>
1403:
1404: <li>
1405:
1406: <p>Empty the <var title="">worker global scope</var>'s <span>list
1407: of active timeouts</span> and its <span>list of active
1408: intervals</span>.</p>
1.50 ihickson 1409:
1.81 ihickson 1410: </li>
1.50 ihickson 1411:
1.123 ihickson 1412: <!-- v2-onclose
1.81 ihickson 1413: <li>
1.50 ihickson 1414:
1.123 ihickson 1415: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1416: object associated with <var title="">worker global scope</var>,
1417: <span>queue a task</span> to <span>fire a simple event</span>
1.115 ihickson 1418: called <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1419:
1.81 ihickson 1420: </li>
1.123 ihickson 1421: -->
1.155 ihickson 1422: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1423: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1424: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1425: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1426: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1427: false, <span>queue a task</span> to <span>fire a simple
1.115 ihickson 1428: event</span> called <code title="event-close">close</code> at the
1.123 ihickson 1429: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1430: --><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 1431: true.</li>
1432:
1.123 ihickson 1433: <!-- v2-onclose
1434: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1435: a worker</span>" processing model defined above immediately starts
1436: running event listeners registered for the <code
1437: title="event-close">close</code> event, this time should not be
1438: zero — the idea is that the <code
1439: title="event-close">close</code> event can be used to clean up
1440: when shutting down unexpectedly.</p></li>
1441: -->
1.81 ihickson 1442:
1.115 ihickson 1443: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1444: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1445: queue">task queues</span><!-- v2-onclose other than the <code
1446: title="event-close">close</code> event that this algorithm just
1447: added-->, discard them without processing them.</li>
1.81 ihickson 1448:
1.123 ihickson 1449: <!-- v2-onclose
1.115 ihickson 1450: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1451: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1452: the script currently running in the worker.</p></li>
1453: -->
1.81 ihickson 1454:
1455: <li><p>Wait a user-agent-defined amount of time.</li>
1456:
1.123 ihickson 1457: <li><p>Abort the script currently running in the worker<!--
1458: v2-onclose (if any script is running, then it will be a handler for
1459: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1460:
1.155 ihickson 1461: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1462: processing model on a worker at any time, e.g. in response to user
1463: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1464: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1465: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1466: 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 1467: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1468: "<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 1469: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1470: true.</li>
1471:
1.115 ihickson 1472: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1473: queued in the <span>event loop</span>'s <span title="task
1474: queue">task queues</span>, discard them without processing
1475: them.</li>
1476:
1477: <li><p>Abort the script currently running in the worker.</li>
1478:
1.115 ihickson 1479: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1480: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1481: worker is a dedicated worker), then empty the <span>port message
1482: queue</span> of the port that the worker's implicit port is
1483: entangled with.</li>
1484:
1.155 ihickson 1485: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1486: <span>DOM manipulation task source</span>.<h3 id="runtime-script-errors"><span class="secno">4.7 </span>Runtime script errors</h3><p>Whenever an uncaught runtime script error occurs in one of the
1.143 ihickson 1487: worker's scripts, if the error did not occur while handling a
1488: previous script error, the user agent must <span>report the
1489: 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>
1.155 ihickson 1490: attribute. <a href="#refsHTML5">[HTML5]</a><p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1491: the error occurred while handling a previous script error, the error
1.155 ihickson 1492: should be reported to the user. <a href="#refsHTML5">[HTML5]</a><p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1493: the error occurred while handling a previous script error, the user
1.123 ihickson 1494: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1495: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1496: 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 1497: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1498: 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 1499: 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 1500: appropriately. The default action of this event depends on whether
1.115 ihickson 1501: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1502: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1503: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1504: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1505: <em>that</em> worker. Otherwise, then the error should be reported
1.155 ihickson 1506: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1507: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : Event {
1.147 ihickson 1508: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1509: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1510: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1511: 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);
1512: void <a href="#dom-errorevent-initerroreventns" title="dom-ErrorEvent-initErrorEventNS">initErrorEventNS</a>(in DOMString namespaceURIArg, in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString messageArg, in DOMString filenameArg, in unsigned long linenoArg);
1.155 ihickson 1513: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.115 ihickson 1514: and <dfn id="dom-errorevent-initerroreventns" title="dom-ErrorEvent-initErrorEventNS"><code>initErrorEventNS()</code></dfn>
1.81 ihickson 1515: methods must initialize the event in a manner analogous to the
1.155 ihickson 1516: similarly-named methods 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>
1517: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1518: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1519: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1520: attribute represents the line number where the error occurred in the
1.155 ihickson 1521: script.<h3 id="creating-workers"><span class="secno">4.8 </span>Creating workers</h3><h4 id="the-abstractworker-abstract-interface"><span class="secno">4.8.1 </span>The <code><a href="#abstractworker">AbstractWorker</a></code> abstract interface</h4><pre class="idl">interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1522: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1523: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.155 ihickson 1524: };</pre><p>Objects implementing the <code><a href="#abstractworker">AbstractWorker</a></code> interface
1525: must also implement the <code>EventTarget</code> interface.<p>The following are the <span>event handler attributes</span> (and their corresponding <span title="event handler event type">event handler event types</span>)
1.102 ihickson 1526: that must be supported, as DOM attributes, by objects implementing
1.155 ihickson 1527: the <code><a href="#abstractworker">AbstractWorker</a></code> interface:<table><thead><tr><th><span title="event handler attributes">event handler attribute</span> <th><span>Event handler event type</span>
1528: <tbody><tr><td><dfn id="handler-abstractworker-onerror" title="handler-AbstractWorker-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.123 ihickson 1529: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.155 ihickson 1530: </table><h4 id="dedicated-workers-and-the-worker-interface"><span class="secno">4.8.2 </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 1531: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1532: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1533:
1.150 ihickson 1534: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, optional in <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1535: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1536: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1537: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1538: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1539: algorithm to be run on the worker with with the object is
1.155 ihickson 1540: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1541: <code>MessagePort</code> associated with them. This port is part of
1542: a channel that is set up when the worker is created, but it is not
1543: exposed. This object must never be garbage collected before the
1.155 ihickson 1544: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1545: at the <code><a href="#worker">Worker</a></code> object.<p>The <dfn id="dom-worker-postmessage" title="dom-Worker-postMessage"><code>postMessage()</code></dfn><!--
1.64 ihickson 1546: and <dfn
1547: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1548: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1549: must act as if, when invoked, it<!--/they (startConversation)-->
1550: immediately invoked the method of the same name on the port, with
1.155 ihickson 1551: the same arguments, and returned the same return value.<p>The following are the <span>event handler attributes</span> (and their corresponding <span title="event handler event type">event handler event types</span>)
1.102 ihickson 1552: that must be supported, as DOM attributes, by objects implementing
1.155 ihickson 1553: the <code><a href="#worker">Worker</a></code> interface:<table><thead><tr><th><span title="event handler attributes">event handler attribute</span> <th><span>Event handler event type</span>
1554: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1555: </table><hr><p>When the <dfn id="dom-worker" title="dom-Worker"><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
1556: 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>first
1.133 ihickson 1557: script</span>'s <span title="script's base URL">base URL</span>,
1558: when the method is invoked.</li>
1.9 ihickson 1559:
1.81 ihickson 1560: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1561: exception.</li>
1.9 ihickson 1562:
1.81 ihickson 1563: <li><p>If the <span>origin</span> of the resulting <span>absolute
1564: URL</span> is not the <span title="same origin">same</span> as the
1.123 ihickson 1565: origin of the <span title="concept-script">script</span> that
1566: invoked the constructor, then throw a <span>security
1567: exception</span>.</li>
1.9 ihickson 1568:
1.115 ihickson 1569: <li><p><span>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1.81 ihickson 1570: object</span>. Let <var title="">worker global scope</var> be this
1571: new object.</li>
1.9 ihickson 1572:
1.115 ihickson 1573: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1574: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1575:
1.81 ihickson 1576: <li><p><span>Create a <code>MessagePort</code> object</span> owned
1.123 ihickson 1577: by the <span title="script's global scope">global scope</span> of
1578: the <span title="concept-script">script</span> that invoked the
1579: constructor. Let this be the <var title="">outside
1.81 ihickson 1580: port</var>.</li>
1.9 ihickson 1581:
1.81 ihickson 1582: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1583:
1.81 ihickson 1584: <li><p><span>Create a <code>MessagePort</code> object</span> owned
1585: by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1586:
1.81 ihickson 1587: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1588:
1.81 ihickson 1589: <li><p><span>Entangle</span> <var title="">outside port</var> and
1590: <var title="">inside port</var>.</li>
1.50 ihickson 1591:
1.81 ihickson 1592: <li><p>Return <var title="">worker</var>, and run the following
1593: steps asynchronously.</li>
1.50 ihickson 1594:
1.126 ihickson 1595: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.81 ihickson 1596: queue</span>.</li>
1.50 ihickson 1597:
1.126 ihickson 1598: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1599: queue</span>.</li>
1.50 ihickson 1600:
1601: <li>
1.51 ihickson 1602:
1.123 ihickson 1603: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1604: <code>Document</code> objects to add</a> given the <span title="script's global scope">global scope</span> of the <span title="concept-script">script</span> that invoked the
1605: constructor.</p>
1606:
1607: </li>
1608:
1609: <li>
1610:
1611: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1612: <var title="">worker global scope</var>'s list of <span>the
1613: worker's <code>Document</code>s</span></a> the
1614: <code>Document</code> objects in <var title="">docs</var>.</p>
1615:
1616: </li>
1617:
1618: <li>
1619:
1.124 ihickson 1620: <p>If the <span title="script's global scope">global scope</span>
1621: of the <span title="concept-script">script</span> that invoked the
1622: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1623: are creating a nested worker), add <var title="">worker global
1624: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1625: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object that is the <span title="script's global scope">global scope</span> of the <span title="concept-script">script</span> that invoked the
1626: constructor.</p>
1627:
1628: </li>
1629:
1630: <li>
1631:
1.115 ihickson 1632: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.81 ihickson 1633: URL</span>, with the <span>script browsing context</span> of the
1634: script that invoked the method as the <var title="">owner browsing
1635: context</var>, and with <var title="">worker global scope</var> as
1636: the global scope.</p>
1.9 ihickson 1637:
1.81 ihickson 1638: </li>
1.4 ihickson 1639:
1.155 ihickson 1640: </ol><p>This constructor must be visible when the <span>script's global
1.135 ihickson 1641: scope</span> is either a <code>Window</code> object or an object
1.155 ihickson 1642: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<h4 id="shared-workers-and-the-sharedworker-interface"><span class="secno">4.8.3 </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 DOMString name)]
1.115 ihickson 1643: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1644: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1645: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1646: attribute must return the value it was assigned by the object's
1647: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1648: 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 1649: constructor is invoked, the user agent must run the following
1.155 ihickson 1650: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1651:
1652: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1653: exception.</li>
1654:
1655: <li><p>If the <span>origin</span> of the resulting <span>absolute
1656: URL</span> is not the <span title="same origin">same</span> as the
1657: origin of the script that invoked the constructor, then throw a
1658: <span>security exception</span>.</li>
1.9 ihickson 1659:
1660: <li>
1661:
1.123 ihickson 1662: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1663: <code>Document</code> objects to add</a> given the <span title="script's global scope">global scope</span> of the <span title="concept-script">script</span> that invoked the
1664: constructor.</p>
1665:
1666: </li>
1667:
1668: <li>
1669:
1.50 ihickson 1670: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1671:
1.155 ihickson 1672: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1673: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1674: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1675:
1.123 ihickson 1676: <li><p><span>Create a <code>MessagePort</code> object</span>
1677: owned by the <span title="script's global scope">global
1678: scope</span> of the script that invoked the method. Let this be
1679: the <var title="">outside port</var>.</li>
1.81 ihickson 1680:
1.115 ihickson 1681: <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 1682:
1.9 ihickson 1683: <li>
1684:
1.115 ihickson 1685: <p>If there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1686: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1687: flag is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1.81 ihickson 1688: exactly equal to the <var title="">name</var> argument, and
1.115 ihickson 1689: whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.81 ihickson 1690: represents an <span>absolute URL</span> that has the <span>same
1691: origin</span> as the resulting <span>absolute URL</span>, then
1692: run these substeps:</p>
1693:
1.155 ihickson 1694: <ol><li><p>Let <var title="">worker global scope</var> be that
1.115 ihickson 1695: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1.81 ihickson 1696:
1.115 ihickson 1697: <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 1698: attribute represents an <span>absolute URL</span> that is not
1699: exactly equal to the resulting <span>absolute URL</span>, then
1700: throw a <code>URL_MISMATCH_ERR</code> exception and abort all
1.127 ihickson 1701: these steps.</li>
1.81 ihickson 1702:
1703: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1704:
1705: <li><p><span>Create a <code>MessagePort</code> object</span>
1706: owned by <var title="">worker global scope</var>. Let this
1707: be the <var title="">inside port</var>.</li>
1708:
1709: <li><p><span>Entangle</span> <var title="">outside port</var>
1710: and <var title="">inside port</var>.</li>
1711:
1712: <li><p>Return <var title="">worker</var> and perform the next
1713: step asynchronously.</li>
1.9 ihickson 1714:
1.81 ihickson 1715: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1716: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1717: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1718: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1719: value is an array containing only the newly created port, and
1720: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1721:
1.123 ihickson 1722: <li>
1723:
1724: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1725: <var title="">worker global scope</var>'s list of <span>the
1726: worker's <code>Document</code>s</span></a> the
1727: <code>Document</code> objects in <var title="">docs</var>.</p>
1728:
1729: </li>
1730:
1.124 ihickson 1731: <li>
1732:
1733: <p>If the <span title="script's global scope">global
1734: scope</span> of the <span title="concept-script">script</span>
1735: that invoked the constructor is a
1736: <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
1737: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1738: object that is the <span title="script's global scope">global
1739: scope</span> of the <span title="concept-script">script</span>
1740: that invoked the constructor.</p>
1741:
1742: </li>
1743:
1.81 ihickson 1744: <li><p>Abort all these steps.</li>
1.9 ihickson 1745:
1.155 ihickson 1746: </ol></li>
1.9 ihickson 1747:
1.115 ihickson 1748: <li><p><span>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1.81 ihickson 1749: object</span>. Let <var title="">worker global scope</var> be
1750: this new object.</li>
1.9 ihickson 1751:
1.81 ihickson 1752: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1753:
1.115 ihickson 1754: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1755: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1756:
1.81 ihickson 1757: <li><p><span>Create a <code>MessagePort</code> object</span>
1758: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1759:
1.81 ihickson 1760: <li><p><span>Entangle</span> <var title="">outside port</var> and
1761: <var title="">inside port</var>.</li>
1.9 ihickson 1762:
1.155 ihickson 1763: </ol></li>
1.28 ihickson 1764:
1.123 ihickson 1765: <li><p>Return <var title="">worker</var> and perform the remaining
1766: steps asynchronously.</li>
1.18 ihickson 1767:
1.81 ihickson 1768: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1769: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1770: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1771: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1772: is an array containing only the newly created port, and <span>queue
1773: a task</span> to dispatch the event at <var title="">worker global
1774: scope</var>.</li>
1.26 ihickson 1775:
1776: <li>
1.46 ihickson 1777:
1.123 ihickson 1778: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1779: <var title="">worker global scope</var>'s list of <span>the
1780: worker's <code>Document</code>s</span></a> the
1781: <code>Document</code> objects in <var title="">docs</var>.</p>
1782:
1783: </li>
1784:
1785: <li>
1786:
1.124 ihickson 1787: <p>If the <span title="script's global scope">global scope</span>
1788: of the <span title="concept-script">script</span> that invoked the
1789: 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
1790: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1791: object that is the <span title="script's global scope">global
1792: scope</span> of the <span title="concept-script">script</span>
1793: that invoked the constructor.</p>
1794:
1795: </li>
1796:
1797: <li>
1798:
1.115 ihickson 1799: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.81 ihickson 1800: URL</span>, with the <span>script browsing context</span> of the
1801: script that invoked the method as the <var title="">owner browsing
1802: context</var>, and with <var title="">worker global scope</var> as
1803: the global scope.</p>
1.26 ihickson 1804:
1.60 ihickson 1805: </li>
1.81 ihickson 1806:
1.155 ihickson 1807: </ol><p>This constructor must be visible when the <span>script's global
1.135 ihickson 1808: scope</span> is either a <code>Window</code> object or an object
1.155 ihickson 1809: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1810: <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 1811: interface <dfn id="workerutils">WorkerUtils</dfn> {
1812: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.115 ihickson 1813: readonly attribute <a href="#worker-navigator" title="worker-Navigator">Navigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 1814: };
1.155 ihickson 1815: // implemented by <a href="#workerglobalscope">WorkerGlobalScope</a></pre><p>Objects that implement the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.115 ihickson 1816: interface must also implement the <code><a href="#workerutils">WorkerUtils</a></code>
1.155 ihickson 1817: interface.<p>Objects that implement the <code><a href="#workerutils">WorkerUtils</a></code> interface
1.81 ihickson 1818: must also implement the <code>WindowTimers</code> interface. (This
1819: interface provides the <code title="">setTimeout()</code> method and
1.155 ihickson 1820: its friends.)</p><!-- XXX ref --><!-- XXX ApplicationCache --><!-- XXX debugging: void log(in DOMString s); // log to console --><hr><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1821: objects, etc) are not available to workers in this version of this
1.155 ihickson 1822: 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 1823: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1824: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1825: anything. Abort these steps.</li>
1826:
1827: <li><p><span title="resolve a url">Resolve</span> each
1828: argument.</li>
1829:
1830: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1831: exception.</li>
1832:
1833: <!--
1.67 ihickson 1834: <li><p>If any of the resulting <span title="absolute URL">absolute
1835: URLs</span> have an <span>origin</span> that is not the <span
1836: title="same origin">same</span> as the origin of the script that
1837: invoked the method, then throw a <span>security
1838: exception</span>.</p></li>
1839: -->
1.26 ihickson 1840:
1841: <li>
1.81 ihickson 1842:
1.45 ihickson 1843: <p>Attempt to <span>fetch</span> each resource identified by the
1.81 ihickson 1844: resulting <span title="absolute URLs">absolute URL</span>.</p>
1845:
1846: </li>
1.26 ihickson 1847:
1848: <li>
1849:
1.81 ihickson 1850: <p>For each argument in turn, in the order given, starting with
1851: the first one, run these substeps:</p>
1.26 ihickson 1852:
1.155 ihickson 1853: <ol><li>
1.26 ihickson 1854:
1.81 ihickson 1855: <p>Wait for the fetching attempt for the corresponding resource
1856: to complete.</p>
1.60 ihickson 1857:
1.81 ihickson 1858: <p>If the fetching attempt failed, throw a
1859: <code>NETWORK_ERR</code> exception and abort all these
1860: steps.</p>
1.45 ihickson 1861:
1.115 ihickson 1862: <p>If the attempt succeeds, then <a href="#decode-a-script-resource" title="decode a script
1.85 ihickson 1863: resource">decode the script resource</a> to obtain its <var title="">source</var>.</p>
1864:
1865: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1866:
1.115 ihickson 1867: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1868: always assumed to be JavaScript, regardless of the MIME
1869: type.</p> <!-- XXX -->
1.61 ihickson 1870:
1.81 ihickson 1871: </li>
1.26 ihickson 1872:
1.81 ihickson 1873: <li>
1.26 ihickson 1874:
1.81 ihickson 1875: <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
1876: same global object, browsing context, character encoding, base
1.115 ihickson 1877: URL, and script group as the <span title="concept-script">script</span> that was created by the
1878: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1879:
1.115 ihickson 1880: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1881: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1882: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1883: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1884:
1.81 ihickson 1885: <p>If it failed to parse, then throw a
1886: <code>SyntaxError</code><!-- XXX ref? --> exception and abort
1887: all these steps.</p>
1.63 ihickson 1888:
1.81 ihickson 1889: <p>If an exception was raised or if the script was prematurely
1890: aborted, then abort all these steps, letting the exception or
1891: aborting continue to be processed by the script that called the
1.115 ihickson 1892: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 1893: method.</p>
1894:
1.115 ihickson 1895: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 1896: worker</a>" algorithms abort the script then abort all these
1897: steps.</p>
1898:
1899: </li>
1900:
1.155 ihickson 1901: </ol></li>
1.152 ihickson 1902:
1.155 ihickson 1903: </ol><h3 id="the-navigator-object"><span class="secno">5.2 </span>The <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> object</h3><p>The <dfn id="dom-worker-navigator" title="dom-worker-navigator"><code>navigator</code></dfn> attribute
1.115 ihickson 1904: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1905: the <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> interface, which
1.93 ihickson 1906: represents the identity and state of the user agent (the
1.155 ihickson 1907: client):<pre class="idl">interface <dfn id="worker-navigator" title="worker-Navigator">Navigator</dfn> {};
1.150 ihickson 1908: <a href="#worker-navigator" title="worker-Navigator">Navigator</a> implements <span>NavigatorID</span>;
1.155 ihickson 1909: <a href="#worker-navigator" title="worker-Navigator">Navigator</a> implements <span>NavigatorOnLine</span>;</pre><p>Objects implementing the <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> interface also implement
1.150 ihickson 1910: the <code>NavigatorID</code> and <code>NavigatorOnLine</code>
1.155 ihickson 1911: interfaces. <a href="#refsHTML5">[HTML5]</a><p class="note">The <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code>
1.93 ihickson 1912: interface defined in this specification is different than the one
1.155 ihickson 1913: defined in the HTML specification.<h3 id="apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</h3><p>The <code title="dom-opendatabase">openDatabase()</code> and
1.115 ihickson 1914: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.155 ihickson 1915: methods are defined in the Web Database specification. <a href="#refsWEBDATABASE">[WEBDATABASE]</a><h3 id="interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</h3><p>There must be no interface objects and constructors available in
1.81 ihickson 1916: the global scope of scripts whose <span>script execution
1.115 ihickson 1917: context</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 1918: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 1919: constructors defined by the XMLHttpRequest specifications, except
1920: that the <span>document response entity body</span> must always be
1.152 ihickson 1921: null. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 1922:
1923: <li><p>The <code>WebSocket</code> interface object and
1.152 ihickson 1924: constructor. <a href="#refsWEBSOCKET">[WEBSOCKET]</a></li>
1.81 ihickson 1925:
1.119 ihickson 1926: <li><p>The <code>EventSource</code> interface object and
1.152 ihickson 1927: constructor. <a href="#refsEVENTSOURCE">[EVENTSOURCE]</a></li>
1.119 ihickson 1928:
1.81 ihickson 1929: <li><p>The <code>MessageChannel</code> interface object and
1.152 ihickson 1930: constructor. <a href="#refsHTML5">[HTML5]</a></li>
1.81 ihickson 1931:
1.115 ihickson 1932: <li><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> and <code title="dom-SharedWorker"><a href="#dom-sharedworker">SharedWorker(<var title="">url</var>)</a></code> constructors.</li>
1.81 ihickson 1933:
1.155 ihickson 1934: </ul><h3 id="worker-locations"><span class="secno">5.5 </span>Worker locations</h3><pre class="idl">interface <dfn id="workerlocation">WorkerLocation</dfn> {
1.115 ihickson 1935: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
1936: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
1937: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
1938: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
1939: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
1940: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
1941: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
1942: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 1943: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
1944: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 1945: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 1946: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.115 ihickson 1947: of <span>URL decomposition attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1948: <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>,
1949: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
1950: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
1951: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
1.81 ihickson 1952: follow the rules given for URL decomposition attributes, with the
1.115 ihickson 1953: <span title="concept-uda-input">input</span> being the
1.81 ihickson 1954: <span>absolute URL</span> that the object represents (same as the
1.115 ihickson 1955: <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and
1956: the <span title="concept-uda-setter">common setter action</span>
1.155 ihickson 1957: being a no-op, since the attributes are defined to be readonly. <a href="#refsHTML5">[HTML5]</a><h2 class="no-num" id="references">References</h2><p>All references are normative unless marked "Non-normative".<dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.153 ihickson 1958: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
1959: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
1960: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1961: S. Byrnes. W3C, April 2004.</dd>
1962: <!--
1963: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
1964: DOM Core</a></cite>, S. Pieters. W3C, June 2009.</dd>
1965: -->
1966:
1.152 ihickson 1967: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
1968: <!--
1969: <dd><cite><a
1970: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
1971: Model (DOM) Level 3 Events Specification</a></cite>,
1972: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C, December
1973: 2007.</dd>
1974: -->
1975: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
1976: Object Model (DOM) Level 3 Events Specification</a></cite>,
1977: D. Schepers. W3C, July 2009.</dd>
1978:
1979: <dt id="refsECMA262">[ECMA262]</dt>
1980: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1981: Language Specification</a></cite>. ECMA, December 1999.</dd>
1982:
1983: <dt id="refsEVENTSOURCE">[EVENTSOURCE]</dt>
1984: <!--
1985: <dd><cite><a href="http://www.w3.org/TR/eventsource/">Server-Sent
1986: Events</a></cite>, I. Hickson. W3C, April 2009.</dd>
1987: -->
1988: <dd><cite><a href="http://dev.w3.org/html5/eventsource/">Server-Sent
1989: Events</a></cite>, I. Hickson. W3C, July 2009.</dd>
1990:
1991: <dt id="refsHTML5">[HTML5]</dt>
1992: <!--
1993: <dd><cite><a href="http://www.w3.org/TR/html5/">HTML 5</a></cite>,
1994: I. Hickson, D. Hyatt. W3C, April 2009.</dd>
1995: <dd><cite><a href="http://www.w3.org/html/wg/html5/">HTML
1996: 5</a></cite>, I. Hickson, D. Hyatt. W3C, August 2009.</dd>
1997: -->
1998: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML
1999: 5</a></cite>, I. Hickson. WHATWG, August 2009.</dd>
2000:
1.154 ihickson 2001: <dt id="refsRFC2119">[RFC2119]</dt>
2002: <dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
2003: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF, March
2004: 1997.</dd>
2005:
1.152 ihickson 2006: <dt id="refsWEBDATABASE">[WEBDATABASE]</dt>
2007: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web
2008: Database</a></cite>, I. Hickson. W3C, July
2009: 2009.</dd>
2010:
1.154 ihickson 2011: <dt id="refsWEBIDL">[WEBIDL]</dt>
2012: <!--
2013: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
2014: IDL</a></cite>, C. McCormack. W3C, December 2008.</dd>
2015: -->
2016: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
2017: IDL</a></cite>, C. McCormack. W3C, July 2009.</dd>
2018:
1.152 ihickson 2019: <dt id="refsWEBSOCKET">[WEBSOCKET]</dt>
2020: <!--
2021: <dd><cite><a href="http://www.w3.org/TR/websockets/">The Web Sockets
2022: API</a></cite>, I. Hickson. W3C, April
2023: 2009.</dd>
2024: -->
2025: <dd><cite><a href="http://dev.w3.org/html5/websockets/">The Web Sockets
2026: API</a></cite>, I. Hickson. W3C, August
2027: 2009.</dd>
2028:
2029: <dt id="refsXHR">[XHR]</dt>
2030: <!--
2031: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
2032: Object</a></cite>, A. van Kesteren. W3C, April
2033: 2008.</dd>
2034: -->
2035: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest/"><code>XMLHttpRequest</code></a></cite>,
2036: A. van Kesteren. W3C, June 2009.</dd>
2037:
1.155 ihickson 2038: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2039:
2040: Aaron Boodman,
1.155 ihickson 2041: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2042: Anne van Kesteren,
2043: Ben Turner,
2044: Dmitry Titov,
1.96 ihickson 2045: Drew Wilson,
1.97 ihickson 2046: Jeremy Orlow,
1.81 ihickson 2047: Jonas Sicking,
2048: Justin James,
2049: Kevin Hakanson,
2050: Maciej Stachowiak,
2051: Michael Nordman,
2052: Mike Smith,
2053:
2054: and
2055:
2056: Philip Taylor
2057:
1.155 ihickson 2058: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2059: technology and whose experience has been a huge influence on this
1.155 ihickson 2060: specification.
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