Annotation of html5/workers/Overview.html, revision 1.176
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1.82 ihickson 66:
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1.155 ihickson 167: </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 168: <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 169: <h1>Web Workers</h1>
1.109 ihickson 170: <!--ZZZ:-->
1.117 ihickson 171: <!--<h2 class="no-num no-toc">W3C Working Draft 23 April 2009</h2>-->
1.176 ! ihickson 172: <h2 class="no-num no-toc" id="editor-s-draft-28-september-2009">Editor's Draft 28 September 2009</h2>
1.109 ihickson 173: <!--:ZZZ-->
1.155 ihickson 174: <dl><!-- ZZZ: update the month/day (twice), (un)comment out
1.117 ihickson 175: <dt>This Version:</dt>
1.115 ihickson 176: <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 177: :ZZZ --><dt>Latest Published Version:</dt>
1.115 ihickson 178: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 179: <dt>Latest Editor's Draft:</dt>
1.115 ihickson 180: <dd><a href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 181: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 182: <dt>Previous Versions:</dt>
1.113 ihickson 183: <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 184: <!-- :ZZZ -->
1.81 ihickson 185: <dt>Editors:</dt>
1.115 ihickson 186: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 187: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
188: © 2009 <a href="http://www.w3.org/"><abbr title="World Wide
189: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 190: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
191: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
192: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
193: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
194: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 195: use</a> rules apply.</p>
1.155 ihickson 196: </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 197: authors to spawn background workers running scripts in parallel to
198: their main page. This allows for thread-like operation with
1.155 ihickson 199: 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 200: time of its publication. Other documents may supersede this
201: document. A list of current W3C publications and the most recently
202: formally published revision of this technical report can be found in
1.115 ihickson 203: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.155 ihickson 204: 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 205: notice in the header by October 2009 unless the spec as a whole has
1.155 ihickson 206: 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 207: version</a> of this specification is available under a license that
1.155 ihickson 208: 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 209: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 210: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 211: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 212:
213: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 214: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
215: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 216: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 217:
1.155 ihickson 218: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 219: stable. <strong>Implementors who are not taking part in the
220: discussions are likely to find the specification changing out from
221: under them in incompatible ways.</strong> Vendors interested in
222: implementing this specification before it eventually reaches the
223: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 224: 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 225: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
226: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 227: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 228: 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 229: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 230: 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 231: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
232: <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>
233: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
234: <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 235: </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 236: Working Group</a> is the W3C working group responsible for this
237: specification's progress along the W3C Recommendation track.
238: <!--ZZZ:-->
1.117 ihickson 239: <!--This specification is the 23 April 2009 Working Draft.-->
1.176 ! ihickson 240: This specification is the 28 September 2009 Editor's Draft.
1.81 ihickson 241: <!--:ZZZ-->
1.155 ihickson 242: </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
243: 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 244: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 245: 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 246: 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 247: any patent disclosures</a> made in connection with the deliverables
248: of the group; that page also includes instructions for disclosing a
249: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 250: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
251: 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 252: 6 of the W3C Patent Policy</a>.<h2 class="no-num no-toc" id="contents">Table of contents</h2>
1.81 ihickson 253: <!--begin-toc-->
1.115 ihickson 254: <ol class="toc">
255: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 256: <ol>
1.115 ihickson 257: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
258: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 259: <ol>
1.115 ihickson 260: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
261: <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>
262: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.3 </span>Worker used for background I/O</a></li>
263: <li><a href="#shared-workers"><span class="secno">1.2.4 </span>Shared workers</a></li>
264: <li><a href="#delegation"><span class="secno">1.2.5 </span>Delegation</a></li>
265: <li><a href="#providing-libraries"><span class="secno">1.2.6 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 266: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 267: <ol>
1.148 ihickson 268: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
269: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
270: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
271: <ol>
272: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 273: <ol>
1.148 ihickson 274: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
275: <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>
276: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> inteface</a></ol></li>
1.160 ihickson 277: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.148 ihickson 278: <li><a href="#decoding-scripts"><span class="secno">4.3 </span>Decoding scripts</a></li>
279: <li><a href="#the-event-loop"><span class="secno">4.4 </span>The event loop</a></li>
280: <li><a href="#the-worker-s-lifetime"><span class="secno">4.5 </span>The worker's lifetime</a></li>
281: <li><a href="#processing-model"><span class="secno">4.6 </span>Processing model</a></li>
282: <li><a href="#runtime-script-errors"><span class="secno">4.7 </span>Runtime script errors</a></li>
283: <li><a href="#creating-workers"><span class="secno">4.8 </span>Creating workers</a>
1.81 ihickson 284: <ol>
1.148 ihickson 285: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.8.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
286: <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>
287: <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>
288: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 289: <ol>
1.148 ihickson 290: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
291: <li><a href="#the-navigator-object"><span class="secno">5.2 </span>The <code title="worker-Navigator">Navigator</code> object</a></li>
292: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
293: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
294: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 295: <li><a class="no-num" href="#references">References</a></li>
296: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 297: <!--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
298: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 299: scripts that respond to clicks or other user interactions, and
300: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 301: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 302: relatively heavy-weight, and are not intended to be used in large
303: numbers. For example, it would be inappropriate to launch one worker
304: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 305: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
306: 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
307: 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
308: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
309: (naïvely) compute prime numbers, and progressively displays the
310: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 311: <html>
312: <head>
313: <title>Worker example: One-core computation</title>
314: </head>
315: <body>
316: <p>The highest prime number discovered so far is: <output id="result"></output></p>
317: <script>
1.50 ihickson 318: var worker = new Worker('worker.js');
319: worker.onmessage = function (event) {
1.54 ihickson 320: document.getElementById('result').textContent = event.data;
1.29 ihickson 321: };
1.81 ihickson 322: </script>
323: </body>
1.155 ihickson 324: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 325: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 326: representing that worker, which is used to communicate with the
1.115 ihickson 327: worker. That object's <code title="handler-Worker-onmessage"><a href="#handler-worker-onmessage">onmessage</a></code> event handler
1.155 ihickson 328: attribute allows the code to receive messages from the worker.<p>The worker itself is as follows:<pre>var n = 1;
1.29 ihickson 329: search: while (true) {
330: n += 1;
331: for (var i = 2; i <= Math.sqrt(n); i += 1)
332: if (n % i == 0)
333: continue search;
334: // found a prime!
1.50 ihickson 335: postMessage(n);
1.155 ihickson 336: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 337: 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 338: 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 339: task is to listen for notifications from the server, and, when
340: appropriate, either add or remove data from the client-side
1.155 ihickson 341: database.<p>Since no communication occurs between the worker and the main
342: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 343: new Worker('worker.js');
1.155 ihickson 344: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 345: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 346: server.onmessage = function (event) {
347: // data is in the format "command key value"
1.54 ihickson 348: var data = event.data.split(' ');
1.31 ihickson 349: switch (data[0]) {
350: case '+':
351: database.transaction(function(tx) {
352: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
353: });
354: case '-':
355: database.transaction(function(tx) {
356: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
357: });
358: }
1.155 ihickson 359: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 360: mechanism and opens the local database (which, we presume, has been
361: created earlier). The worker then just listens for messages from the
362: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 363: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 364: this example online</a>. (This example will not actually function,
365: since the server does not actually exist and the database is not
1.155 ihickson 366: 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 367: fetching stock updates for at regular intervals, and one for
1.155 ihickson 368: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 369: <html>
370: <head>
371: <title>Worker example: Stock ticker</title>
372: <script>
1.33 ihickson 373: // TICKER
374: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 375: var ticker = new Worker('ticker.js');
1.33 ihickson 376:
377: // SEARCHER
1.50 ihickson 378: var searcher = new Worker('searcher.js');
1.33 ihickson 379: function search(query) {
1.50 ihickson 380: searcher.postMessage(query);
1.33 ihickson 381: }
382:
383: // SYMBOL SELECTION UI
384: function select(newSymbol) {
385: symbol = newSymbol;
1.50 ihickson 386: ticker.postMessage(symbol);
1.33 ihickson 387: }
1.81 ihickson 388: </script>
389: </head>
1.122 ihickson 390: <body onload="search('')">
1.81 ihickson 391: <p><output id="symbol"></output> <output id="value"></output></p>
392: <script>
1.50 ihickson 393: ticker.onmessage = function (event) {
1.54 ihickson 394: var data = event.data.split(' ');
1.33 ihickson 395: document.getElementById('symbol').textContent = data[0];
396: document.getElementById('value').textContent = data[1];
397: };
1.50 ihickson 398: ticker.postMessage(symbol);
1.81 ihickson 399: </script>
1.122 ihickson 400: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 401: <ul id="results"></ul>
402: <script>
1.50 ihickson 403: searcher.onmessage = function (event) {
1.54 ihickson 404: var data = event.data.split(' ');
1.33 ihickson 405: var results = document.getElementById('results');
406: while (results.hasChildNodes()) // clear previous results
407: results.removeChild(results.firstChild);
408: for (var i = 0; i < data.length; i += 1) {
409: // add a list item with a button for each result
410: var li = document.createElement('li');
411: var button = document.createElement('button');
412: button.value = data[i];
413: button.type = 'button';
414: button.onclick = function () { select(this.value); };
415: button.textContent = data[i];
416: li.appendChild(button);
417: results.appendChild(li);
418: }
419: };
1.81 ihickson 420: </script>
421: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
422: </body>
1.155 ihickson 423: </html></pre><p>The two workers use a common library for performing the actual
424: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 425: try {
426: var xhr = new XMLHttpRequest();
427: xhr.open('GET', url, false);
428: xhr.send();
429: return xhr.responseText;
430: } catch (e) {
431: return ''; // turn all errors into empty results
432: }
1.155 ihickson 433: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 434: var timer;
435: var symbol;
436: function update() {
1.50 ihickson 437: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 438: timer = setTimeout(update, 10000);
439: }
1.50 ihickson 440: onmessage = function (event) {
1.33 ihickson 441: if (timer)
442: clearTimeout(timer);
1.54 ihickson 443: symbol = event.data;
1.33 ihickson 444: update();
1.155 ihickson 445: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 446: onmessage = function (event) {
1.54 ihickson 447: postMessage(get('search.cgi?' + event.data));
1.155 ihickson 448: };</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 449: are all viewing the same map. All the windows share the same map
450: information, with a single worker coordinating all the viewers. Each
451: viewer can move around independently, but if they set any data on
1.155 ihickson 452: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
453: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 454: <html>
455: <head>
456: <title>Workers example: Multiviewer</title>
457: <script>
1.36 ihickson 458: function openViewer() {
459: window.open('viewer.html');
460: }
1.81 ihickson 461: </script>
462: </head>
463: <body>
464: <p><button type=button onclick="openViewer()">Open a new
465: viewer</button></p>
466: <p>Each viewer opens in a new window. You can have as many viewers
467: as you like, they all view the same data.</p>
468: </body>
1.155 ihickson 469: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 470: <html>
471: <head>
472: <title>Workers example: Multiviewer viewer</title>
473: <script>
1.50 ihickson 474: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 475:
476: // CONFIGURATION
477: function configure(event) {
1.54 ihickson 478: if (event.data.substr(0, 4) != 'cfg ') return;
479: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 480: // update display to mention our name is name
481: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
482: // no longer need this listener
1.43 ihickson 483: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 484: }
1.53 ihickson 485: worker.port.addEventListener('message', configure, false);
1.36 ihickson 486:
487: // MAP
488: function paintMap(event) {
1.54 ihickson 489: if (event.data.substr(0, 4) != 'map ') return;
490: var data = event.data.substr(4).split(',');
1.36 ihickson 491: // display tiles data[0] .. data[8]
492: var canvas = document.getElementById('map');
493: var context = canvas.getContext('2d');
494: for (var y = 0; y < 3; y += 1) {
495: for (var x = 0; x < 3; x += 1) {
496: var tile = data[y * 3 + x];
497: if (tile == '0')
498: context.fillStyle = 'green';
499: else
500: context.fillStyle = 'maroon';
501: fillRect(x * 50, y * 50, 50, 50);
502: }
503: }
504: }
1.53 ihickson 505: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 506:
507: // PUBLIC CHAT
508: function updatePublicChat(event) {
1.54 ihickson 509: if (event.data.substr(0, 4) != 'txt ') return;
510: var name = event.data.substr(4).split(' ', 1);
511: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 512: // display "<name> message" in public chat
1.36 ihickson 513: var dialog = document.getElementById('public');
514: var dt = document.createElement('dt');
515: dt.textContent = name;
516: dialog.appendChild(dt);
517: var dd = document.createElement('dd');
518: dd.textContent = message;
519: dialog.appendChild(dd);
520: }
1.53 ihickson 521: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 522:
523: // PRIVATE CHAT
524: function startPrivateChat(event) {
1.54 ihickson 525: if (event.data.substr(0, 4) != 'msg ') return;
526: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 527: var port = event.ports[0];
1.36 ihickson 528: // display a private chat UI
529: var ul = document.getElementById('private');
530: var li = document.createElement('li');
531: var h3 = document.createElement('h3');
532: h3.textContent = 'Private chat with ' + name;
533: li.appendChild(h3);
534: var dialog = document.createElement('dialog');
535: var addMessage = function(name, message) {
536: var dt = document.createElement('dt');
537: dt.textContent = name;
538: dialog.appendChild(dt);
539: var dd = document.createElement('dd');
540: dd.textContent = message;
541: dialog.appendChild(dd);
542: };
543: port.onmessage = function (event) {
1.54 ihickson 544: addMessage(name, event.data);
1.36 ihickson 545: };
546: li.appendChild(dialog);
547: var form = document.createElement('form');
548: var p = document.createElement('p');
549: var input = document.createElement('input');
550: input.size = 50;
551: p.appendChild(input);
552: p.appendChild(document.createTextNode(' '));
553: var button = document.createElement('button');
554: button.textContent = 'Post';
555: p.appendChild(button);
556: form.onsubmit = function () {
557: port.postMessage(input.value);
558: addMessage('me', input.value);
559: input.value = '';
560: return false;
561: };
562: form.appendChild(p);
563: li.appendChild(form);
564: }
1.53 ihickson 565: worker.port.addEventListener('message', startPrivateChat, false);
1.81 ihickson 566: </script>
567: </head>
568: <body>
569: <h1>Viewer</h1>
570: <h2>Map</h2>
571: <p><canvas id="map" height=150 width=150></canvas></p>
572: <p>
573: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
574: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
575: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
576: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
577: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
578: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
579: </p>
580: <h2>Public Chat</h2>
581: <dialog id="public"></dialog>
582: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
583: <p>
584: <input type="text" name="message" size="50">
585: <button>Post</button>
586: </p>
587: </form>
588: <h2>Private Chat</h2>
589: <ul id="private"></ul>
590: </body>
591: </html>
1.155 ihickson 592: </pre><p>There are several key things worth noting about the way the
593: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 594: processing function, the code here attaches multiple event
595: listeners, each one performing a quick check to see if it is
596: relevant for the message. In this example it doesn't make much
597: difference, but if multiple authors wanted to collaborate using a
598: single port to communicate with a worker, it would allow for
599: independent code instead of changes having to all be made to a
1.155 ihickson 600: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 601: unregister specific listeners when you are done with them, as is
602: done with the <code title="">configure()</code> method in this
1.155 ihickson 603: example.<p>Finally, the worker:<pre>
604: var nextName = 0;
1.36 ihickson 605: function getNextName() {
606: // this could use more friendly names
607: // but for now just return a number
608: return nextName++;
609: }
610:
611: var map = [
612: [0, 0, 0, 0, 0, 0, 0],
613: [1, 1, 0, 1, 0, 1, 1],
614: [0, 1, 0, 1, 0, 0, 0],
615: [0, 1, 0, 1, 0, 1, 1],
616: [0, 0, 0, 1, 0, 0, 0],
617: [1, 0, 0, 1, 1, 1, 1],
618: [1, 1, 0, 1, 1, 0, 1],
619: ];
620:
621: function wrapX(x) {
622: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 623: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 624: return x;
625: }
626:
627: function wrapY(y) {
628: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 629: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 630: return y;
631: }
632:
1.50 ihickson 633: function sendMapData(callback) {
1.36 ihickson 634: var data = '';
635: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
636: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
637: if (data != '')
638: data += ',';
639: data += map[y][x];
640: }
641: }
1.50 ihickson 642: callback('map ' + data);
1.36 ihickson 643: }
644:
645: var viewers = {};
646: onconnect = function (event) {
1.84 ihickson 647: event.ports[0]._name = getNextName();
648: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
649: viewers[event.ports[0]._name] = event.port._data;
650: event.ports[0].postMessage('cfg ' + name);
651: event.ports[0].onmessage = getMessage;
652: sendMapData(event.ports[0].postMessage);
1.36 ihickson 653: };
654:
655: function getMessage(event) {
1.54 ihickson 656: switch (event.data.substr(0, 4)) {
1.36 ihickson 657: case 'mov ':
1.54 ihickson 658: var direction = event.data.substr(4);
1.36 ihickson 659: var dx = 0;
660: var dy = 0;
661: switch (direction) {
662: case 'up': dy = -1; break;
663: case 'down': dy = 1; break;
664: case 'left': dx = -1; break;
665: case 'right': dx = 1; break;
666: }
667: event.target._data.x = wrapX(event.target._data.x + dx);
668: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 669: sendMapData(event.target.postMessage);
1.36 ihickson 670: break;
671: case 'set ':
1.54 ihickson 672: var value = event.data.substr(4);
1.36 ihickson 673: map[event.target._data.y][event.target._data.x] = value;
674: for (var viewer in viewers)
1.50 ihickson 675: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 676: break;
677: case 'txt ':
678: var name = event.target._name;
1.54 ihickson 679: var message = event.data.substr(4);
1.36 ihickson 680: for (var viewer in viewers)
681: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
682: break;
683: case 'msg ':
684: var party1 = event._data;
1.54 ihickson 685: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 686: if (party2) {
687: var channel = new MessageChannel();
1.84 ihickson 688: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
689: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 690: }
691: break;
692: }
1.155 ihickson 693: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 694: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 695: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 696: "msg" message from one viewer naming another viewer, it sets up a
697: direct connection between the two, so that the two viewers can
698: communicate directly without the worker having to proxy all the
1.155 ihickson 699: 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 700: performance is to split computationally expensive tasks amongst
701: multiple workers. In this example, a computationally expensive task
702: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 703: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 704: <html>
705: <head>
706: <title>Worker example: One-core computation</title>
707: </head>
708: <body>
709: <p>The highest prime number discovered so far is: <output id="result"></output></p>
710: <script>
1.50 ihickson 711: var worker = new Worker('worker.js');
712: worker.onmessage = function (event) {
1.54 ihickson 713: document.getElementById('result').textContent = event.data;
1.40 ihickson 714: };
1.81 ihickson 715: </script>
716: </body>
1.155 ihickson 717: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 718: var num_workers = 10;
719: var items_per_worker = 1000000;
720:
721: // start the workers
722: var result = 0;
723: var pending_workers = num_workers;
724: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 725: var worker = new Worker('core.js');
726: worker.postMessage(i * items_per_worker);
727: worker.postMessage((i+1) * items_per_worker);
728: worker.onmessage = storeResult;
1.40 ihickson 729: }
730:
731: // handle the results
732: function storeResult(event) {
1.54 ihickson 733: result += 1*event.data;
1.40 ihickson 734: pending_workers -= 1;
735: if (pending_workers <= 0)
1.50 ihickson 736: postMessage(result); // finished!
1.155 ihickson 737: }</pre><p>It consists of a loop to start the subworkers, and then a handler
738: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 739: onmessage = getStart;
1.40 ihickson 740: function getStart(event) {
1.54 ihickson 741: start = 1*event.data;
1.40 ihickson 742: onmessage = getEnd;
743: }
744:
745: var end;
746: function getEnd(event) {
1.54 ihickson 747: end = 1*event.data;
1.40 ihickson 748: onmessage = null;
1.66 ihickson 749: work();
1.40 ihickson 750: }
751:
1.66 ihickson 752: function work() {
1.40 ihickson 753: var result = 0;
754: for (var i = start; i < end; i += 1) {
755: // perform some complex calculation here
756: result += 1;
757: }
1.50 ihickson 758: postMessage(result);
759: close();
1.155 ihickson 760: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 761: for the range of numbers thus specified, and then report the result
1.155 ihickson 762: 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
763: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 764:
765: <dd>Takes a port, on which it will send two messages, first the
766: public key and then the private key.</dd>
767:
768: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
769:
770: <dd>Takes a port, to which any number of messages can be sent, the
771: first giving the public key, and the remainder giving the
772: plaintext, each of which is encrypted and then sent on that same
773: channel as the cyphertext. The user can close the port when it is
774: done encrypting content.</dd>
775:
776: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
777:
778: <dd>Takes a port, to which any number of messages can be sent, the
779: first giving the private key, and the remainder giving the
780: cyphertext, each of which is decrypted and then sent on that same
781: channel as the plaintext. The user can close the port when it is
782: done decrypting content.</dd>
1.49 ihickson 783:
1.155 ihickson 784: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 785: if (e.data == "genkeys")
1.84 ihickson 786: genkeys(e.ports[0]);
1.54 ihickson 787: else if (e.data == "encrypt")
1.84 ihickson 788: encrypt(e.ports[0]);
1.54 ihickson 789: else if (e.data == "decrypt")
1.84 ihickson 790: decrypt(e.ports[0]);
1.49 ihickson 791: }
792:
793: function genkeys(p) {
794: var keys = _generateKeyPair();
795: p.postMessage(keys[0]);
796: p.postMessage(keys[1]);
797: }
798:
799: function encrypt(p) {
800: var key, state = 0;
801: p.onmessage = function (e) {
802: if (state == 0) {
1.54 ihickson 803: key = e.data;
1.49 ihickson 804: state = 1;
805: } else {
1.54 ihickson 806: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 807: }
808: };
809: }
810:
811: function decrypt(p) {
812: var key, state = 0;
813: p.onmessage = function (e) {
814: if (state == 0) {
1.54 ihickson 815: key = e.data;
1.49 ihickson 816: state = 1;
817: } else {
1.54 ihickson 818: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 819: }
820: };
821: }
822:
1.50 ihickson 823: // support being used as a shared worker as well as a dedicated worker
824: if (this.onmessage) // dedicated worker
825: onmessage = handleMessage;
826: else // shared worker
827: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 828:
829:
830: // the "crypto" functions:
831:
832: function _generateKeyPair() {
833: return [Math.random(), Math.random()];
834: }
835:
836: function _encrypt(k, s) {
837: return 'encrypted-' + k + ' ' + s;
838: }
839:
840: function _decrypt(k, s) {
841: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 842: }</pre><p>Note that the crypto functions here are just stubs and don't do
843: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 844: <html>
845: <head>
846: <title>Worker example: Crypto library</title>
847: <script>
1.50 ihickson 848: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 849: function getKeys() {
850: var state = 0;
1.50 ihickson 851: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 852: if (state == 0)
1.54 ihickson 853: document.getElementById('public').value = e.data;
1.49 ihickson 854: else if (state == 1)
1.54 ihickson 855: document.getElementById('private').value = e.data;
1.49 ihickson 856: state += 1;
857: };
858: }
859: function enc() {
1.50 ihickson 860: var port = cryptoLib.startConversation("encrypt");
861: port.postMessage(document.getElementById('public').value);
862: port.postMessage(document.getElementById('input').value);
863: port.onmessage = function (e) {
1.54 ihickson 864: document.getElementById('input').value = e.data;
1.50 ihickson 865: port.close();
1.49 ihickson 866: };
867: }
868: function dec() {
1.50 ihickson 869: var port = cryptoLib.startConversation("decrypt");
870: port.postMessage(document.getElementById('private').value);
871: port.postMessage(document.getElementById('input').value);
872: port.onmessage = function (e) {
1.54 ihickson 873: document.getElementById('input').value = e.data;
1.50 ihickson 874: port.close();
1.49 ihickson 875: };
876: }
1.81 ihickson 877: </script>
878: <style>
1.49 ihickson 879: textarea { display: block; }
1.81 ihickson 880: </style>
881: </head>
882: <body onload="getKeys()">
883: <fieldset>
884: <legend>Keys</legend>
885: <p><label>Public Key: <textarea id="public"></textarea></label></p>
886: <p><label>Private Key: <textarea id="private"></textarea></label></p>
887: </fieldset>
888: <p><label>Input: <textarea id="input"></textarea></label></p>
889: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
890: </body>
1.155 ihickson 891: </html></pre><p>A later version of the API, though, might want to offload all the
892: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 893: if (e.data == "genkeys")
1.84 ihickson 894: genkeys(e.ports[0]);
1.54 ihickson 895: else if (e.data == "encrypt")
1.84 ihickson 896: encrypt(e.ports[0]);
1.54 ihickson 897: else if (e.data == "decrypt")
1.84 ihickson 898: decrypt(e.ports[0]);
1.49 ihickson 899: }
900:
901: function genkeys(p) {
1.50 ihickson 902: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 903: generator.postMessage('', [p]);
1.49 ihickson 904: }
905:
906: function encrypt(p) {
907: p.onmessage = function (e) {
1.54 ihickson 908: var key = e.data;
1.50 ihickson 909: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 910: encryptor.postMessage(key, [p]);
1.49 ihickson 911: };
912: }
913:
914: function encrypt(p) {
915: p.onmessage = function (e) {
1.54 ihickson 916: var key = e.data;
1.50 ihickson 917: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 918: decryptor.postMessage(key, [p]);
1.49 ihickson 919: };
920: }
921:
1.50 ihickson 922: // support being used as a shared worker as well as a dedicated worker
923: if (this.onmessage) // dedicated worker
924: onmessage = handleMessage;
925: else // shared worker
1.84 ihickson 926: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 927: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 928: var k = _generateKeyPair();
1.84 ihickson 929: e.ports[0].postMessage(k[0]);
930: e.ports[0].postMessage(k[1]);
1.49 ihickson 931: close();
932: }
1.50 ihickson 933:
934: function _generateKeyPair() {
935: return [Math.random(), Math.random()];
1.155 ihickson 936: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 937: var key = e.data;
1.84 ihickson 938: e.ports[0].onmessage = function (e) {
1.54 ihickson 939: var s = e.data;
1.50 ihickson 940: postMessage(_encrypt(key, s));
1.49 ihickson 941: }
1.50 ihickson 942: }
943:
944: function _encrypt(k, s) {
945: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 946: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 947: var key = e.data;
1.84 ihickson 948: e.ports[0].onmessage = function (e) {
1.54 ihickson 949: var s = e.data;
1.50 ihickson 950: postMessage(_decrypt(key, s));
1.49 ihickson 951: }
1.50 ihickson 952: }
953:
954: function _decrypt(k, s) {
955: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 956: }</pre><p>Notice how the users of the API don't have to even know that this
957: is happening — the API hasn't changed; the library can
1.81 ihickson 958: delegate to subworkers without changing its API, even though it is
1.155 ihickson 959: 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 960: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 961: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 962: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
963: "OPTIONAL" in the normative parts of this document are to be
964: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 965: 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 966: (such as "strip any leading space characters" or "return false and
967: abort these steps") are to be interpreted with the meaning of the
968: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 969: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 970: attributes, methods or objects. Such requirements are to be
1.155 ihickson 971: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 972: may be implemented in any manner, so long as the end result is
973: equivalent. (In particular, the algorithms defined in this
974: specification are intended to be easy to follow, and not intended to
1.155 ihickson 975: be performant.)<p>The only conformance class defined by this specification is user
976: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 977: otherwise unconstrained inputs, e.g. to prevent denial of service
978: attacks, to guard against running out of memory, or to work around
1.155 ihickson 979: platform-specific limitations.<h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3><p>This specification relies on several other underlying
980: specifications.<dl><dt>HTML5</dt>
1.49 ihickson 981:
1.81 ihickson 982: <dd>
1.49 ihickson 983:
1.81 ihickson 984: <p>Many fundamental concepts from HTML5 are used by this
1.152 ihickson 985: specification. <a href="#refsHTML5">[HTML5]</a></p>
1.49 ihickson 986:
1.81 ihickson 987: </dd>
1.1 ihickson 988:
1.81 ihickson 989: <dt>WebIDL</dt>
1.1 ihickson 990:
991: <dd>
992:
1.81 ihickson 993: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 994: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 995:
1.81 ihickson 996: </dd>
1.1 ihickson 997:
1.155 ihickson 998: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 999: <code title="">Foo</code> is actually an interface, is sometimes
1000: used instead of the more accurate "an object implementing the
1.155 ihickson 1001: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1002: scripts in Web applications, and does not necessarily imply the
1003: existence of an actual <code>Document</code> object or of any other
1004: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 1005: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1006: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1007: <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 1008: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1009: 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 1010: workers. Dedicated workers, once created, and are linked to their
1011: creator; but message ports can be used to communicate from a
1012: dedicated worker to multiple other browsing contexts or
1013: workers. Shared workers, on the other hand, are named, and once
1014: created any script running in the same <span>origin</span> can
1.155 ihickson 1015: 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 1016: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1017: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1018:
1019: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1020: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1021: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1022: };
1.172 ihickson 1023: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
1024: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <span>EventTarget</span>;</pre><p>The <dfn id="dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self"><code>self</code></dfn> attribute
1.155 ihickson 1025: 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 1026: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1027: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1028: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1029: 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 1030: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1031: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1032: have been added to the <span>event loop</span>'s <span title="task
1033: queue">task queues</span>.</p>
1034:
1035: <!-- v2-onclose
1036: <li><p><span>Queue a task</span> to <span>fire a simple
1.115 ihickson 1037: event</span> called <code title="event-close">close</code> at the
1.123 ihickson 1038: <code>WorkerGlobalScope</code> object.</p></li>
1039: -->
1.81 ihickson 1040:
1.115 ihickson 1041: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1042: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1043: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1044:
1.124 ihickson 1045: <li><p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1.123 ihickson 1046: ports</a>.</li>
1.81 ihickson 1047:
1.155 ihickson 1048: </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>)
1.163 ihickson 1049: that must be supported, as IDL attributes, by objects implementing
1.155 ihickson 1050: 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>
1051: <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>
1052: </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 1053: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.174 ihickson 1054: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.77 ihickson 1055: <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1056: attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1057: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1058: had an implicit <code>MessagePort</code> associated with them. This
1059: port is part of a channel that is set up when the worker is created,
1060: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1061: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1062: 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 1063: and <dfn
1064: title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
1.81 ihickson 1065: method<!--s (startConversation)--> on
1.115 ihickson 1066: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.81 ihickson 1067: invoked, it<!--/they (startConversation)--> immediately invoked the
1068: method of the same name on the port, with the same arguments, and
1.155 ihickson 1069: returned the same return value.<p>The following are the <span>event handler attributes</span> (and
1.123 ihickson 1070: their corresponding <span title="event handler event type">event
1.163 ihickson 1071: handler event types</span>) that must be supported, as IDL
1.123 ihickson 1072: attributes, by objects implementing the
1.155 ihickson 1073: <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>
1074: <tbody><tr><td><dfn id="handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1075: </table><p>For the purposes of the <span>offline application cache</span>
1.101 ihickson 1076: networking model, a dedicated worker is an extension of the
1.155 ihickson 1077: <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 1078: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1079: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1080: readonly attribute <span>ApplicationCache</span> <a href="#dom-sharedworkerglobalscope-applicationcache" title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</a>;
1.144 ihickson 1081: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1082: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1083: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1084: attribute must return the value it was assigned when the
1.115 ihickson 1085: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1086: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1087: that can be used to obtain a reference to the worker using the
1.155 ihickson 1088: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handler attributes</span> (and
1.123 ihickson 1089: their corresponding <span title="event handler event type">event
1.163 ihickson 1090: handler event types</span>) that must be supported, as IDL
1.123 ihickson 1091: attributes, by objects implementing the
1.155 ihickson 1092: <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>
1093: <tbody><tr><td><dfn id="handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect"><code>onconnect</code></dfn> <td> <code title="event-connect">connect</code>
1094: </table><p>For the purposes of the <span>offline application cache</span>
1.101 ihickson 1095: networking model, a shared worker is its own <span>cache
1.115 ihickson 1096: host</span>. The <a href="#run-a-worker">run a worker</a> algorithm takes care of
1.155 ihickson 1097: 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 1098: attribute returns the <code>ApplicationCache</code> object for the
1.101 ihickson 1099: worker.</p><!-- normative conf criteria is in the appcache section
1.160 ihickson 1100: --><h3 id="origins-of-workers"><span class="secno">4.2 </span>Origins of workers</h3><p>Both the <span>origin</span> and <span>effective script
1.81 ihickson 1101: origin</span> of scripts running in workers are the
1102: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1103: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.155 ihickson 1104: 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
1105: obtain its source in Unicode, it must run the following steps:<ol><li>
1.85 ihickson 1106:
1107: <p>Let <var title="">character encoding</var> be <i title="">unknown</i>.</p>
1108:
1109: </li>
1110:
1111: <li>
1112:
1113: <p>For each of the rows in the following table, starting with the
1114: first one and going down, if the resource has as many or more
1115: bytes available than the number of bytes in the first column, and
1116: the first bytes of the resource match the bytes given in the first
1117: column, then let <var title="">character encoding</var> be the
1118: encoding given in the cell in the second column of that row:</p>
1119:
1120: <!-- this table is present in several forms in this file; keep them in sync -->
1.155 ihickson 1121: <table><thead><tr><th>Bytes in Hexadecimal
1.85 ihickson 1122: <th>Encoding
1.155 ihickson 1123: <tbody><!-- nobody uses this
1.85 ihickson 1124: <tr>
1125: <td>00 00 FE FF
1126: <td>UTF-32BE
1127: <tr>
1128: <td>FF FE 00 00
1129: <td>UTF-32LE
1.155 ihickson 1130: --><tr><td>FE FF
1.85 ihickson 1131: <td>UTF-16BE
1.155 ihickson 1132: <tr><td>FF FE
1.85 ihickson 1133: <td>UTF-16LE
1.155 ihickson 1134: <tr><td>EF BB BF
1.85 ihickson 1135: <td>UTF-8
1136: <!-- nobody uses this
1137: <tr>
1138: <td>DD 73 66 73
1139: <td>UTF-EBCDIC
1140: -->
1.155 ihickson 1141: </table><p class="note">This step looks for Unicode Byte Order Marks
1.85 ihickson 1142: (BOMs).</p>
1143:
1144: </li>
1145:
1146: <li>
1147:
1148: <p>If <var title="">character encoding</var> is still <i title="">unknown</i>, apply the <span>algorithm for extracting an
1.115 ihickson 1149: encoding from a Content-Type</span> to the resource's <span title="Content-Type">Content Type metadata</span>; if this returns
1.85 ihickson 1150: an encoding, and the user agent supports that encoding, then let
1151: <var title="">character encoding</var> be that encoding.</p>
1152:
1153: </li>
1154:
1155: <li>
1156:
1157: <p>If <var title="">character encoding</var> is still <i title="">unknown</i>, then let <var title="">character
1158: encoding</var> be UTF-8.</p>
1159:
1160: </li>
1161:
1162: <li>
1163:
1164: <p>Convert the resource to Unicode using the character encoding
1165: given by <var title="">character encoding</var>.</p>
1166:
1167: <p>Return the text that is so obtained.</p>
1168:
1169: </li>
1170:
1.155 ihickson 1171: </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 1172: loop</span> distinct from those defined for <span title="unit of
1173: related similar-origin browsing contexts">units of related
1174: similar-origin browsing contexts</span>. This <span>event
1175: loop</span> has no associated <span>browsing context</span>, and its
1176: <span title="task queue">task queues</span> only have events,
1177: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1178: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1179: <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 1180: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1181: 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 1182: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1183: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1184: already on the queue are unaffected except where otherwise
1.115 ihickson 1185: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1186: timers stop firing, notifications for all pending asynchronous
1.155 ihickson 1187: 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
1188: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1189: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1190: consists of all the <code>MessagePort</code> objects that are
1191: entangled with another port and that have one (but only one) port
1192: owned by <var title="">worker global scope</var>. This list includes
1193: <!--all the <code>MessagePort</code> objects that are in events
1.68 ihickson 1194: pending in the <span>event loop</span>, as well as (commented out
1195: because in practice it makes no difference either way as far as I
1196: can tell, and it would be hard to strictly implement since these
1.81 ihickson 1197: ports might not yet be across the thread boundary)--> the implicit
1.155 ihickson 1198: <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 1199: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1200: 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 1201: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1202: 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 1203: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1204: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1205: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1206: <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 1207: documents">add <var title="">d</var> to <var title="">q</var>'s
1208: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.155 ihickson 1209: <code>Document</code>s</span></a>.</p><!-- suggestions welcome
1210: on making this sentence into understandable English --><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1211: Document">discarded</span>, it must be removed from the list of
1212: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.155 ihickson 1213: whose list contains that <code>Document</code>.<p>Given a <span>script's global scope</span> <var title="">o</var>
1.123 ihickson 1214: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1215: <code>Document</code> objects to add</dfn> depends on the type of
1216: <var title="">o</var>. If <var title="">o</var> is a
1217: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1218: nested worker), then the relevant <code>Document</code>s are the
1219: <code>Document</code>s that are in <var title="">o</var>'s own list
1220: 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
1221: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1222: <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 1223: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1224: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1225: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1226: timers, database transactions, or network connections, or its list
1.124 ihickson 1227: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1228: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1229: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1230: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1231: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1232: <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 1233: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.155 ihickson 1234: <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
1.176 ! ihickson 1235: <span>URL</span> <var title="">url</var>, a browsing context <var title="">owner browsing context</var>, an origin <var title="">owner
! 1236: origin</var>, and with global scope <var title="">worker global
! 1237: scope</var>, it must run the following steps:<ol><li>
1.81 ihickson 1238:
1239: <p>Create a completely separate and parallel execution environment
1240: (i.e. a separate thread or process or equivalent construct), and
1.106 ihickson 1241: run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1242:
1243: </li>
1.4 ihickson 1244:
1.101 ihickson 1245: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1246: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1247: shared worker), and there are any <span title="relevant application
1248: cache">relevant application caches</span> that are identified by a
1249: 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 1250: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1251: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1252: cache</span> of those that match.</li>
1253:
1.4 ihickson 1254: <li>
1.52 ihickson 1255:
1.176 ! ihickson 1256: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>.</p>
! 1257: <!-- not http-origin privacy sensitive -->
1.81 ihickson 1258:
1.129 ihickson 1259: <p>If the attempt fails, or if the attempt involves any redirects
1260: 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
1261: origin</span> as the original <var title="">url</var>), then for
1262: each <code><a href="#worker">Worker</a></code> or <code><a href="#sharedworker">SharedWorker</a></code> object
1263: associated with <var title="">worker global scope</var>,
1264: <span>queue a task</span> to <span>fire a simple event</span>
1265: called <code title="event-error">error</code> at that
1266: object. Abort these steps.</p>
1.7 ihickson 1267:
1.115 ihickson 1268: <p>If the attempt succeeds, then <a href="#decode-a-script-resource" title="decode a script
1.85 ihickson 1269: resource">decode the script resource</a> to obtain its <var title="">source</var>.</p>
1.81 ihickson 1270:
1.68 ihickson 1271: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1272:
1.115 ihickson 1273: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1274: type of the script is ignored. Unlike with <code>script</code>
1275: elements, there is no way to override the type. It's always
1.170 ihickson 1276: assumed to be JavaScript.</p>
1.81 ihickson 1277:
1278: </li>
1.7 ihickson 1279:
1280: <li>
1.68 ihickson 1281:
1.115 ihickson 1282: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1283: created, as follows.</p>
1284:
1285: <p>Create a new <span>script execution environment</span>
1286: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1287:
1.68 ihickson 1288: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1289: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1290: entry-points</span>; set the <i>initial code entry-point</i> to
1291: the entry-point for any executable code to be immediately run.</p>
1292:
1293: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1294:
1295: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1296:
1.83 ihickson 1297: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1298: UTF-8. (This is just used for encoding non-ASCII characters in the
1299: query component of URLs.)</p>
1.68 ihickson 1300:
1301: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1302:
1.81 ihickson 1303: </li>
1.4 ihickson 1304:
1305: <li>
1.81 ihickson 1306:
1307: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1308: worker such that no sooner than it stops being either a
1309: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1310: worker</a>, and no later than it stops being a
1311: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1312: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1313: to true<!-- v2-onclose and <span title="queue a task">a task is
1314: queued</span> to <span>fire a simple event</span> called <code
1315: title="event-close">close</code> at <var title="">worker global
1316: scope</var>-->.</p>
1.81 ihickson 1317:
1318: </li>
1.9 ihickson 1319:
1320: <li>
1.7 ihickson 1321:
1.81 ihickson 1322: <p><strong>Suspending workers</strong>: Start monitoring the
1323: worker, such that whenever <var title="">worker global
1.115 ihickson 1324: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1325: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1326: agent suspends execution of script in that worker until such time
1.115 ihickson 1327: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1328: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1329: worker</a>.</p>
1.4 ihickson 1330:
1.81 ihickson 1331: </li>
1.68 ihickson 1332:
1333: <li>
1.4 ihickson 1334:
1.81 ihickson 1335: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1336: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1337: entry-point</i>, and let that run until it either returns, fails
1338: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1339: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1340: algorithms defined below.</p>
1341:
1.149 ihickson 1342: <!-- v2-onclose
1343: <p class="note">If the script gets aborted by the "<span>kill a
1344: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1345: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1346: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1347: for the <code title="message-close">close</code> event. The
1.149 ihickson 1348: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1349: events.</p>
1.149 ihickson 1350: -->
1.4 ihickson 1351:
1.81 ihickson 1352: </li>
1.4 ihickson 1353:
1.95 ihickson 1354: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1355: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1356: a dedicated worker), then enable the <span>port message
1357: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1358:
1.4 ihickson 1359: <li>
1.68 ihickson 1360:
1.115 ihickson 1361: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1362: 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 1363: to true.</p>
1.43 ihickson 1364:
1.81 ihickson 1365: </li>
1.4 ihickson 1366:
1367: <li>
1368:
1.81 ihickson 1369: <p>Run the oldest task on one of the <span>event loop</span>'s
1370: <span title="task queue">task queues</span>, if any. The user
1371: agent may pick any <span>task queue</span>.</p>
1372:
1.115 ihickson 1373: <p class="note">The handling of events or the execution of
1374: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1375: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1376: defined below.</p>
1.8 ihickson 1377:
1.81 ihickson 1378: </li>
1.4 ihickson 1379:
1380: <li>
1381:
1.81 ihickson 1382: <p>Remove the task run in the previous step, if any, from its
1383: <span>task queue</span>.</p>
1.4 ihickson 1384:
1.81 ihickson 1385: </li>
1.4 ihickson 1386:
1387: <li>
1.8 ihickson 1388:
1.81 ihickson 1389: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1390: <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 1391: to false, then jump back to the step above labeled <i>event
1392: loop</i>.</p>
1.8 ihickson 1393:
1.81 ihickson 1394: </li>
1.8 ihickson 1395:
1396: <li>
1.71 ihickson 1397:
1.123 ihickson 1398: <p>If there are any outstanding transactions that have callbacks
1399: that involve <span title="concept-script">scripts</span> whose
1400: <span title="script's global object">global object</span> is the
1401: <var title="">worker global scope</var>, roll them back (without
1402: invoking any of the callbacks).</p>
1.50 ihickson 1403:
1.123 ihickson 1404: </li>
1405:
1406: <li>
1407:
1408: <p>Empty the <var title="">worker global scope</var>'s <span>list
1409: of active timeouts</span> and its <span>list of active
1410: intervals</span>.</p>
1.50 ihickson 1411:
1.81 ihickson 1412: </li>
1.50 ihickson 1413:
1.123 ihickson 1414: <!-- v2-onclose
1.81 ihickson 1415: <li>
1.50 ihickson 1416:
1.123 ihickson 1417: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1418: object associated with <var title="">worker global scope</var>,
1419: <span>queue a task</span> to <span>fire a simple event</span>
1.115 ihickson 1420: called <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1421:
1.81 ihickson 1422: </li>
1.123 ihickson 1423: -->
1.155 ihickson 1424: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1425: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1426: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1427: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1428: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1429: false, <span>queue a task</span> to <span>fire a simple
1.115 ihickson 1430: event</span> called <code title="event-close">close</code> at the
1.123 ihickson 1431: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1432: --><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 1433: true.</li>
1434:
1.123 ihickson 1435: <!-- v2-onclose
1436: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1437: a worker</span>" processing model defined above immediately starts
1438: running event listeners registered for the <code
1439: title="event-close">close</code> event, this time should not be
1440: zero — the idea is that the <code
1441: title="event-close">close</code> event can be used to clean up
1442: when shutting down unexpectedly.</p></li>
1443: -->
1.81 ihickson 1444:
1.115 ihickson 1445: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1446: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1447: queue">task queues</span><!-- v2-onclose other than the <code
1448: title="event-close">close</code> event that this algorithm just
1449: added-->, discard them without processing them.</li>
1.81 ihickson 1450:
1.123 ihickson 1451: <!-- v2-onclose
1.115 ihickson 1452: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1453: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1454: the script currently running in the worker.</p></li>
1455: -->
1.81 ihickson 1456:
1457: <li><p>Wait a user-agent-defined amount of time.</li>
1458:
1.123 ihickson 1459: <li><p>Abort the script currently running in the worker<!--
1460: v2-onclose (if any script is running, then it will be a handler for
1461: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1462:
1.155 ihickson 1463: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1464: processing model on a worker at any time, e.g. in response to user
1465: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1466: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1467: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1468: 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 1469: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1470: "<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 1471: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1472: true.</li>
1473:
1.115 ihickson 1474: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1475: queued in the <span>event loop</span>'s <span title="task
1476: queue">task queues</span>, discard them without processing
1477: them.</li>
1478:
1479: <li><p>Abort the script currently running in the worker.</li>
1480:
1.115 ihickson 1481: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1482: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1483: worker is a dedicated worker), then empty the <span>port message
1484: queue</span> of the port that the worker's implicit port is
1485: entangled with.</li>
1486:
1.155 ihickson 1487: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1488: <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 1489: worker's scripts, if the error did not occur while handling a
1490: previous script error, the user agent must <span>report the
1491: 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 1492: 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 1493: the error occurred while handling a previous script error, the error
1.155 ihickson 1494: 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 1495: the error occurred while handling a previous script error, the user
1.123 ihickson 1496: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1497: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1498: 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 1499: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1500: 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 1501: 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 1502: appropriately. The default action of this event depends on whether
1.115 ihickson 1503: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1504: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1505: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1506: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1507: <em>that</em> worker. Otherwise, then the error should be reported
1.155 ihickson 1508: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1509: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : Event {
1.147 ihickson 1510: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1511: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1512: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1513: 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);
1514: 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 1515: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.115 ihickson 1516: and <dfn id="dom-errorevent-initerroreventns" title="dom-ErrorEvent-initErrorEventNS"><code>initErrorEventNS()</code></dfn>
1.81 ihickson 1517: methods must initialize the event in a manner analogous to the
1.155 ihickson 1518: 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>
1519: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1520: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1521: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1522: attribute represents the line number where the error occurred in the
1.155 ihickson 1523: 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 1524: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1525: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.172 ihickson 1526: };
1527: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handler attributes</span> (and their corresponding <span title="event handler event type">event handler event types</span>)
1.163 ihickson 1528: that must be supported, as IDL attributes, by objects implementing
1.155 ihickson 1529: 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>
1530: <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 1531: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.155 ihickson 1532: </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 1533: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1534: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1535:
1.174 ihickson 1536: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1537: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1538: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1539: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1540: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1541: algorithm to be run on the worker with with the object is
1.155 ihickson 1542: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1543: <code>MessagePort</code> associated with them. This port is part of
1544: a channel that is set up when the worker is created, but it is not
1545: exposed. This object must never be garbage collected before the
1.155 ihickson 1546: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1547: 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 1548: and <dfn
1549: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1550: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1551: must act as if, when invoked, it<!--/they (startConversation)-->
1552: immediately invoked the method of the same name on the port, with
1.155 ihickson 1553: 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>)
1.163 ihickson 1554: that must be supported, as IDL attributes, by objects implementing
1.155 ihickson 1555: 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>
1556: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1557: </table><hr><p>When the <dfn id="dom-worker" title="dom-Worker"><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
1558: 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 1559: script</span>'s <span title="script's base URL">base URL</span>,
1560: when the method is invoked.</li>
1.9 ihickson 1561:
1.81 ihickson 1562: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1563: exception.</li>
1.9 ihickson 1564:
1.167 ihickson 1565: <li>
1566:
1567: <p>If the <span>origin</span> of the resulting <span>absolute
1568: URL</span> is not the <span title="same origin">same</span> as the
1.176 ! ihickson 1569: origin of the <span>first script</span>, then throw a
! 1570: <span>security exception</span>.</p>
1.167 ihickson 1571:
1572: <p class="note">Thus, scripts must be external files with the same
1573: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1574: URL, and a <code>http:</code> page couldn't start workers using
1575: scripts with <code>http:</code> URLs.</p>
1576:
1577: </li>
1.9 ihickson 1578:
1.115 ihickson 1579: <li><p><span>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1.81 ihickson 1580: object</span>. Let <var title="">worker global scope</var> be this
1581: new object.</li>
1.9 ihickson 1582:
1.115 ihickson 1583: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1584: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1585:
1.81 ihickson 1586: <li><p><span>Create a <code>MessagePort</code> object</span> owned
1.123 ihickson 1587: by the <span title="script's global scope">global scope</span> of
1588: the <span title="concept-script">script</span> that invoked the
1589: constructor. Let this be the <var title="">outside
1.81 ihickson 1590: port</var>.</li>
1.9 ihickson 1591:
1.81 ihickson 1592: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1593:
1.81 ihickson 1594: <li><p><span>Create a <code>MessagePort</code> object</span> owned
1595: by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1596:
1.81 ihickson 1597: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1598:
1.81 ihickson 1599: <li><p><span>Entangle</span> <var title="">outside port</var> and
1600: <var title="">inside port</var>.</li>
1.50 ihickson 1601:
1.81 ihickson 1602: <li><p>Return <var title="">worker</var>, and run the following
1603: steps asynchronously.</li>
1.50 ihickson 1604:
1.126 ihickson 1605: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.81 ihickson 1606: queue</span>.</li>
1.50 ihickson 1607:
1.126 ihickson 1608: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1609: queue</span>.</li>
1.50 ihickson 1610:
1611: <li>
1.51 ihickson 1612:
1.123 ihickson 1613: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1614: <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
1615: constructor.</p>
1616:
1617: </li>
1618:
1619: <li>
1620:
1621: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1622: <var title="">worker global scope</var>'s list of <span>the
1623: worker's <code>Document</code>s</span></a> the
1624: <code>Document</code> objects in <var title="">docs</var>.</p>
1625:
1626: </li>
1627:
1628: <li>
1629:
1.124 ihickson 1630: <p>If the <span title="script's global scope">global scope</span>
1631: of the <span title="concept-script">script</span> that invoked the
1632: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1633: are creating a nested worker), add <var title="">worker global
1634: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1635: <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
1636: constructor.</p>
1637:
1638: </li>
1639:
1640: <li>
1641:
1.115 ihickson 1642: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.81 ihickson 1643: URL</span>, with the <span>script browsing context</span> of the
1644: script that invoked the method as the <var title="">owner browsing
1.176 ! ihickson 1645: context</var>, with the <span>origin</span> of the <span>first
! 1646: script</span> as the <var title="">owner origin</var>, and with
! 1647: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1648:
1.81 ihickson 1649: </li>
1.4 ihickson 1650:
1.155 ihickson 1651: </ol><p>This constructor must be visible when the <span>script's global
1.135 ihickson 1652: scope</span> is either a <code>Window</code> object or an object
1.174 ihickson 1653: 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 optional DOMString name)]
1.115 ihickson 1654: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1655: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1656: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1657: attribute must return the value it was assigned by the object's
1658: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1659: 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 1660: constructor is invoked, the user agent must run the following
1.155 ihickson 1661: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1662:
1663: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1664: exception.</li>
1665:
1.159 ihickson 1666: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1667: resulting <span>absolute URL</span>.</li>
1668:
1669: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1670: argument, or the empty string if the second argument was
1671: omitted.</li>
1.159 ihickson 1672:
1.167 ihickson 1673: <li>
1674:
1675: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1676: not the <span title="same origin">same</span> as the origin of the
1.176 ! ihickson 1677: <span>first script</span>, then throw a <span>security
1.167 ihickson 1678: exception</span>.</p>
1679:
1680: <p class="note">Thus, scripts must be external files with the same
1681: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1682: URL, and a <code>http:</code> page couldn't start workers using
1683: scripts with <code>http:</code> URLs.</p>
1684:
1685: </li>
1.9 ihickson 1686:
1687: <li>
1688:
1.123 ihickson 1689: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1690: <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
1691: constructor.</p>
1692:
1693: </li>
1694:
1695: <li>
1696:
1.50 ihickson 1697: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1698:
1.155 ihickson 1699: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1700: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1701: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1702:
1.123 ihickson 1703: <li><p><span>Create a <code>MessagePort</code> object</span>
1704: owned by the <span title="script's global scope">global
1705: scope</span> of the script that invoked the method. Let this be
1706: the <var title="">outside port</var>.</li>
1.81 ihickson 1707:
1.115 ihickson 1708: <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 1709:
1.164 ihickson 1710: <li><p>Let <var title="">worker global scope</var> be
1711: null.</li>
1712:
1713: <li><p>If <var title="">name</var> is not the empty string and
1714: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1715: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1716: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1717: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1718: represents an <span>absolute URL</span> with the <span>same
1719: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1720: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1721:
1722: <li><p>Otherwise, if <var title="">name</var> is the empty string
1723: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1724: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1725: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1726: is exactly equal to <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1727: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1728:
1.9 ihickson 1729: <li>
1730:
1.164 ihickson 1731: <p>If <var title="">worker global scope</var> is not null, then
1732: run these steps:</p>
1.81 ihickson 1733:
1.164 ihickson 1734: <ol><li><p>If <var title="">worker global scope</var>'s <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code>
1.81 ihickson 1735: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1736: exactly equal to <var title="">scriptURL</var>, then throw a
1737: <code>URL_MISMATCH_ERR</code> exception and abort all these
1738: steps.</li>
1.81 ihickson 1739:
1740: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1741:
1742: <li><p><span>Create a <code>MessagePort</code> object</span>
1743: owned by <var title="">worker global scope</var>. Let this
1744: be the <var title="">inside port</var>.</li>
1745:
1746: <li><p><span>Entangle</span> <var title="">outside port</var>
1747: and <var title="">inside port</var>.</li>
1748:
1749: <li><p>Return <var title="">worker</var> and perform the next
1750: step asynchronously.</li>
1.9 ihickson 1751:
1.81 ihickson 1752: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1753: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1754: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1755: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1756: value is an array containing only the newly created port, and
1757: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1758:
1.123 ihickson 1759: <li>
1760:
1761: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1762: <var title="">worker global scope</var>'s list of <span>the
1763: worker's <code>Document</code>s</span></a> the
1764: <code>Document</code> objects in <var title="">docs</var>.</p>
1765:
1766: </li>
1767:
1.124 ihickson 1768: <li>
1769:
1770: <p>If the <span title="script's global scope">global
1771: scope</span> of the <span title="concept-script">script</span>
1772: that invoked the constructor is a
1773: <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
1774: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1775: object that is the <span title="script's global scope">global
1776: scope</span> of the <span title="concept-script">script</span>
1777: that invoked the constructor.</p>
1778:
1779: </li>
1780:
1.81 ihickson 1781: <li><p>Abort all these steps.</li>
1.9 ihickson 1782:
1.155 ihickson 1783: </ol></li>
1.9 ihickson 1784:
1.115 ihickson 1785: <li><p><span>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1.81 ihickson 1786: object</span>. Let <var title="">worker global scope</var> be
1787: this new object.</li>
1.9 ihickson 1788:
1.81 ihickson 1789: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1790:
1.115 ihickson 1791: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1792: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1793:
1.81 ihickson 1794: <li><p><span>Create a <code>MessagePort</code> object</span>
1795: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1796:
1.81 ihickson 1797: <li><p><span>Entangle</span> <var title="">outside port</var> and
1798: <var title="">inside port</var>.</li>
1.9 ihickson 1799:
1.155 ihickson 1800: </ol></li>
1.28 ihickson 1801:
1.123 ihickson 1802: <li><p>Return <var title="">worker</var> and perform the remaining
1803: steps asynchronously.</li>
1.18 ihickson 1804:
1.81 ihickson 1805: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1806: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1807: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1808: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1809: is an array containing only the newly created port, and <span>queue
1810: a task</span> to dispatch the event at <var title="">worker global
1811: scope</var>.</li>
1.26 ihickson 1812:
1813: <li>
1.46 ihickson 1814:
1.123 ihickson 1815: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1816: <var title="">worker global scope</var>'s list of <span>the
1817: worker's <code>Document</code>s</span></a> the
1818: <code>Document</code> objects in <var title="">docs</var>.</p>
1819:
1820: </li>
1821:
1822: <li>
1823:
1.124 ihickson 1824: <p>If the <span title="script's global scope">global scope</span>
1825: of the <span title="concept-script">script</span> that invoked the
1826: 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
1827: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1828: object that is the <span title="script's global scope">global
1829: scope</span> of the <span title="concept-script">script</span>
1830: that invoked the constructor.</p>
1831:
1832: </li>
1833:
1834: <li>
1835:
1.159 ihickson 1836: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1837: with the <span>script browsing context</span> of the script that
1838: invoked the method as the <var title="">owner browsing
1.176 ! ihickson 1839: context</var>, with the <span>origin</span> of the <span>first
! 1840: script</span> as the <var title="">owner origin</var>, and with
! 1841: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1842:
1.60 ihickson 1843: </li>
1.81 ihickson 1844:
1.155 ihickson 1845: </ol><p>This constructor must be visible when the <span>script's global
1.135 ihickson 1846: scope</span> is either a <code>Window</code> object or an object
1.155 ihickson 1847: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1848: <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 1849: interface <dfn id="workerutils">WorkerUtils</dfn> {
1850: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.115 ihickson 1851: 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 1852: };
1.172 ihickson 1853: <a href="#workerutils">WorkerUtils</a> implement <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1854: objects, etc) are not available to workers in this version of this
1.155 ihickson 1855: 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 1856: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1857: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1858: anything. Abort these steps.</li>
1859:
1860: <li><p><span title="resolve a url">Resolve</span> each
1861: argument.</li>
1862:
1863: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1864: exception.</li>
1865:
1866: <!--
1.67 ihickson 1867: <li><p>If any of the resulting <span title="absolute URL">absolute
1868: URLs</span> have an <span>origin</span> that is not the <span
1869: title="same origin">same</span> as the origin of the script that
1870: invoked the method, then throw a <span>security
1871: exception</span>.</p></li>
1872: -->
1.26 ihickson 1873:
1874: <li>
1.81 ihickson 1875:
1.45 ihickson 1876: <p>Attempt to <span>fetch</span> each resource identified by the
1.176 ! ihickson 1877: resulting <span title="absolute URLs">absolute URL</span>, from
! 1878: the <span>first script</span>'s <span>origin</span>.</p> <!-- not
! 1879: http-origin privacy sensitive -->
1.81 ihickson 1880:
1881: </li>
1.26 ihickson 1882:
1883: <li>
1884:
1.81 ihickson 1885: <p>For each argument in turn, in the order given, starting with
1886: the first one, run these substeps:</p>
1.26 ihickson 1887:
1.155 ihickson 1888: <ol><li>
1.26 ihickson 1889:
1.81 ihickson 1890: <p>Wait for the fetching attempt for the corresponding resource
1891: to complete.</p>
1.60 ihickson 1892:
1.81 ihickson 1893: <p>If the fetching attempt failed, throw a
1894: <code>NETWORK_ERR</code> exception and abort all these
1895: steps.</p>
1.45 ihickson 1896:
1.115 ihickson 1897: <p>If the attempt succeeds, then <a href="#decode-a-script-resource" title="decode a script
1.85 ihickson 1898: resource">decode the script resource</a> to obtain its <var title="">source</var>.</p>
1899:
1900: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1901:
1.115 ihickson 1902: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1903: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1904: type.</p>
1.61 ihickson 1905:
1.81 ihickson 1906: </li>
1.26 ihickson 1907:
1.81 ihickson 1908: <li>
1.26 ihickson 1909:
1.81 ihickson 1910: <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
1911: same global object, browsing context, character encoding, base
1.115 ihickson 1912: URL, and script group as the <span title="concept-script">script</span> that was created by the
1913: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1914:
1.115 ihickson 1915: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1916: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1917: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1918: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1919:
1.170 ihickson 1920: <p>If it failed to parse, then throw a <code>SyntaxError</code>
1921: exception and abort all these steps.</p>
1.63 ihickson 1922:
1.81 ihickson 1923: <p>If an exception was raised or if the script was prematurely
1924: aborted, then abort all these steps, letting the exception or
1925: aborting continue to be processed by the script that called the
1.115 ihickson 1926: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 1927: method.</p>
1928:
1.115 ihickson 1929: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 1930: worker</a>" algorithms abort the script then abort all these
1931: steps.</p>
1932:
1933: </li>
1934:
1.155 ihickson 1935: </ol></li>
1.152 ihickson 1936:
1.155 ihickson 1937: </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 1938: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1939: the <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> interface, which
1.93 ihickson 1940: represents the identity and state of the user agent (the
1.155 ihickson 1941: client):<pre class="idl">interface <dfn id="worker-navigator" title="worker-Navigator">Navigator</dfn> {};
1.150 ihickson 1942: <a href="#worker-navigator" title="worker-Navigator">Navigator</a> implements <span>NavigatorID</span>;
1.155 ihickson 1943: <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 1944: the <code>NavigatorID</code> and <code>NavigatorOnLine</code>
1.155 ihickson 1945: interfaces. <a href="#refsHTML5">[HTML5]</a><p class="note">The <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code>
1.93 ihickson 1946: interface defined in this specification is different than the one
1.155 ihickson 1947: 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 1948: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.155 ihickson 1949: 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 1950: the global scope of scripts whose <span>script execution
1.115 ihickson 1951: context</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 1952: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 1953: constructors defined by the XMLHttpRequest specifications, except
1954: that the <span>document response entity body</span> must always be
1.160 ihickson 1955: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
1956: <span>script's base URL</span>; the
1957: <span><code>XMLHttpRequest</code> origin</span> is the script's
1958: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 1959:
1960: <li><p>The <code>WebSocket</code> interface object and
1.152 ihickson 1961: constructor. <a href="#refsWEBSOCKET">[WEBSOCKET]</a></li>
1.81 ihickson 1962:
1.119 ihickson 1963: <li><p>The <code>EventSource</code> interface object and
1.152 ihickson 1964: constructor. <a href="#refsEVENTSOURCE">[EVENTSOURCE]</a></li>
1.119 ihickson 1965:
1.81 ihickson 1966: <li><p>The <code>MessageChannel</code> interface object and
1.152 ihickson 1967: constructor. <a href="#refsHTML5">[HTML5]</a></li>
1.81 ihickson 1968:
1.115 ihickson 1969: <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 1970:
1.155 ihickson 1971: </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 1972: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
1973: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
1974: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
1975: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
1976: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
1977: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
1978: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
1979: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 1980: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
1981: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 1982: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 1983: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 1984: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 1985: <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>,
1986: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
1987: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
1988: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
1.163 ihickson 1989: follow the rules given for URL decomposition IDL attributes, with the
1.115 ihickson 1990: <span title="concept-uda-input">input</span> being the
1.81 ihickson 1991: <span>absolute URL</span> that the object represents (same as the
1.115 ihickson 1992: <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and
1993: the <span title="concept-uda-setter">common setter action</span>
1.157 ihickson 1994: 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><!--REFS--><p>All references are normative unless marked "Non-normative".<dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.153 ihickson 1995: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
1996: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
1997: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1998: S. Byrnes. W3C, April 2004.</dd>
1999: <!--
2000: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
2001: DOM Core</a></cite>, S. Pieters. W3C, June 2009.</dd>
2002: -->
2003:
1.152 ihickson 2004: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
2005: <!--
2006: <dd><cite><a
2007: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
2008: Model (DOM) Level 3 Events Specification</a></cite>,
2009: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C, December
2010: 2007.</dd>
2011: -->
2012: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
2013: Object Model (DOM) Level 3 Events Specification</a></cite>,
2014: D. Schepers. W3C, July 2009.</dd>
2015:
2016: <dt id="refsECMA262">[ECMA262]</dt>
2017: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
2018: Language Specification</a></cite>. ECMA, December 1999.</dd>
2019:
2020: <dt id="refsEVENTSOURCE">[EVENTSOURCE]</dt>
2021: <!--
2022: <dd><cite><a href="http://www.w3.org/TR/eventsource/">Server-Sent
2023: Events</a></cite>, I. Hickson. W3C, April 2009.</dd>
2024: -->
2025: <dd><cite><a href="http://dev.w3.org/html5/eventsource/">Server-Sent
2026: Events</a></cite>, I. Hickson. W3C, July 2009.</dd>
2027:
2028: <dt id="refsHTML5">[HTML5]</dt>
2029: <!--
1.161 ihickson 2030: <dd><cite><a href="http://www.w3.org/TR/html5/">HTML5</a></cite>,
1.152 ihickson 2031: I. Hickson, D. Hyatt. W3C, April 2009.</dd>
1.161 ihickson 2032: <dd><cite><a
2033: href="http://www.w3.org/html/wg/html5/">HTML5</a></cite>,
2034: I. Hickson, D. Hyatt. W3C, August 2009.</dd>
1.152 ihickson 2035: -->
1.161 ihickson 2036: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML5</a></cite>,
2037: I. Hickson. WHATWG, August 2009.</dd>
1.152 ihickson 2038:
1.154 ihickson 2039: <dt id="refsRFC2119">[RFC2119]</dt>
2040: <dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
2041: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF, March
2042: 1997.</dd>
2043:
1.152 ihickson 2044: <dt id="refsWEBDATABASE">[WEBDATABASE]</dt>
2045: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web
2046: Database</a></cite>, I. Hickson. W3C, July
2047: 2009.</dd>
2048:
1.154 ihickson 2049: <dt id="refsWEBIDL">[WEBIDL]</dt>
2050: <!--
2051: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
2052: IDL</a></cite>, C. McCormack. W3C, December 2008.</dd>
2053: -->
2054: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
2055: IDL</a></cite>, C. McCormack. W3C, July 2009.</dd>
2056:
1.152 ihickson 2057: <dt id="refsWEBSOCKET">[WEBSOCKET]</dt>
2058: <!--
2059: <dd><cite><a href="http://www.w3.org/TR/websockets/">The Web Sockets
2060: API</a></cite>, I. Hickson. W3C, April
2061: 2009.</dd>
2062: -->
2063: <dd><cite><a href="http://dev.w3.org/html5/websockets/">The Web Sockets
2064: API</a></cite>, I. Hickson. W3C, August
2065: 2009.</dd>
2066:
2067: <dt id="refsXHR">[XHR]</dt>
2068: <!--
2069: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
2070: Object</a></cite>, A. van Kesteren. W3C, April
2071: 2008.</dd>
2072: -->
1.160 ihickson 2073: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.152 ihickson 2074: A. van Kesteren. W3C, June 2009.</dd>
2075:
1.155 ihickson 2076: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2077:
2078: Aaron Boodman,
1.155 ihickson 2079: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2080: Anne van Kesteren,
2081: Ben Turner,
2082: Dmitry Titov,
1.96 ihickson 2083: Drew Wilson,
1.97 ihickson 2084: Jeremy Orlow,
1.81 ihickson 2085: Jonas Sicking,
2086: Justin James,
2087: Kevin Hakanson,
2088: Maciej Stachowiak,
2089: Michael Nordman,
2090: Mike Smith,
2091:
2092: and
2093:
2094: Philip Taylor
2095:
1.155 ihickson 2096: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2097: technology and whose experience has been a huge influence on this
1.155 ihickson 2098: specification.
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