Annotation of html5/workers/Overview.html, revision 1.200
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1.198 ihickson 168: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><div class="head">
1.115 ihickson 169: <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 170: <h1>Web Workers</h1>
1.196 ihickson 171:
1.199 ihickson 172: <h2 class="no-num no-toc" id="editor-s-draft-1-december-2009">Editor's Draft 1 December 2009</h2>
1.198 ihickson 173: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 174: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 175: <dt>Latest Editor's Draft:</dt>
1.115 ihickson 176: <dd><a href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 177: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 178: <dt>Previous Versions:</dt>
1.113 ihickson 179: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20090423/">http://www.w3.org/TR/2009/WD-workers-20090423/</a>
1.198 ihickson 180: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20091029/">http://www.w3.org/TR/2009/WD-workers-20091029/</a></dd>
1.117 ihickson 181: <!-- :ZZZ -->
1.81 ihickson 182: <dt>Editors:</dt>
1.115 ihickson 183: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 184: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
185: © 2009 <a href="http://www.w3.org/"><abbr title="World Wide
186: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 187: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
188: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
189: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
190: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
191: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 192: use</a> rules apply.</p>
1.155 ihickson 193: </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 194: authors to spawn background workers running scripts in parallel to
195: their main page. This allows for thread-like operation with
1.155 ihickson 196: 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 197: time of its publication. Other documents may supersede this
198: document. A list of current W3C publications and the most recently
199: formally published revision of this technical report can be found in
1.115 ihickson 200: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.155 ihickson 201: 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 202: notice in the header by October 2009 unless the spec as a whole has
1.155 ihickson 203: 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 204: version</a> of this specification is available under a license that
1.155 ihickson 205: 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 206: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 207: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 208: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 209:
210: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 211: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
212: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 213: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 214:
1.155 ihickson 215: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 216: stable. <strong>Implementors who are not taking part in the
217: discussions are likely to find the specification changing out from
218: under them in incompatible ways.</strong> Vendors interested in
219: implementing this specification before it eventually reaches the
220: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 221: 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 222: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
223: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 224: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 225: 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 226: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 227: 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 228: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
229: <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>
230: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
231: <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 232: </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 233: Working Group</a> is the W3C working group responsible for this
234: specification's progress along the W3C Recommendation track.
1.196 ihickson 235:
1.199 ihickson 236: This specification is the 1 December 2009 Editor's Draft.
1.155 ihickson 237: </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
238: 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 239: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 240: 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 241: 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 242: any patent disclosures</a> made in connection with the deliverables
243: of the group; that page also includes instructions for disclosing a
244: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 245: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
246: 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 247: 6 of the W3C Patent Policy</a>.<h2 class="no-num no-toc" id="contents">Table of contents</h2>
1.81 ihickson 248: <!--begin-toc-->
1.115 ihickson 249: <ol class="toc">
250: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 251: <ol>
1.115 ihickson 252: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
253: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 254: <ol>
1.115 ihickson 255: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
256: <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>
257: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.3 </span>Worker used for background I/O</a></li>
258: <li><a href="#shared-workers"><span class="secno">1.2.4 </span>Shared workers</a></li>
259: <li><a href="#delegation"><span class="secno">1.2.5 </span>Delegation</a></li>
260: <li><a href="#providing-libraries"><span class="secno">1.2.6 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 261: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 262: <ol>
1.148 ihickson 263: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
264: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
265: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
266: <ol>
267: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 268: <ol>
1.148 ihickson 269: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
270: <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>
271: <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 272: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.186 ihickson 273: <li><a href="#the-event-loop"><span class="secno">4.3 </span>The event loop</a></li>
274: <li><a href="#the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</a></li>
275: <li><a href="#processing-model"><span class="secno">4.5 </span>Processing model</a></li>
276: <li><a href="#runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</a></li>
277: <li><a href="#creating-workers"><span class="secno">4.7 </span>Creating workers</a>
1.81 ihickson 278: <ol>
1.186 ihickson 279: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
280: <li><a href="#dedicated-workers-and-the-worker-interface"><span class="secno">4.7.2 </span>Dedicated workers and the <code>Worker</code> interface</a></li>
281: <li><a href="#shared-workers-and-the-sharedworker-interface"><span class="secno">4.7.3 </span>Shared workers and the <code>SharedWorker</code> interface</a></ol></ol></li>
1.148 ihickson 282: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 283: <ol>
1.148 ihickson 284: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
285: <li><a href="#the-navigator-object"><span class="secno">5.2 </span>The <code title="worker-Navigator">Navigator</code> object</a></li>
286: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
287: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
288: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 289: <li><a class="no-num" href="#references">References</a></li>
290: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 291: <!--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
292: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 293: scripts that respond to clicks or other user interactions, and
294: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 295: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 296: relatively heavy-weight, and are not intended to be used in large
297: numbers. For example, it would be inappropriate to launch one worker
298: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 299: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
300: 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
301: 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
302: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
303: (naïvely) compute prime numbers, and progressively displays the
304: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 305: <html>
306: <head>
307: <title>Worker example: One-core computation</title>
308: </head>
309: <body>
310: <p>The highest prime number discovered so far is: <output id="result"></output></p>
311: <script>
1.50 ihickson 312: var worker = new Worker('worker.js');
313: worker.onmessage = function (event) {
1.54 ihickson 314: document.getElementById('result').textContent = event.data;
1.29 ihickson 315: };
1.81 ihickson 316: </script>
317: </body>
1.155 ihickson 318: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 319: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 320: representing that worker, which is used to communicate with the
1.177 ihickson 321: worker. That object's <code title="handler-Worker-onmessage"><a href="#handler-worker-onmessage">onmessage</a></code> event handler allows the code to receive messages from the worker.<p>The worker itself is as follows:<pre>var n = 1;
1.29 ihickson 322: search: while (true) {
323: n += 1;
324: for (var i = 2; i <= Math.sqrt(n); i += 1)
325: if (n % i == 0)
326: continue search;
327: // found a prime!
1.50 ihickson 328: postMessage(n);
1.155 ihickson 329: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 330: 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 331: 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 332: task is to listen for notifications from the server, and, when
333: appropriate, either add or remove data from the client-side
1.155 ihickson 334: database.<p>Since no communication occurs between the worker and the main
335: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 336: new Worker('worker.js');
1.155 ihickson 337: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 338: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 339: server.onmessage = function (event) {
340: // data is in the format "command key value"
1.54 ihickson 341: var data = event.data.split(' ');
1.31 ihickson 342: switch (data[0]) {
343: case '+':
344: database.transaction(function(tx) {
345: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
346: });
347: case '-':
348: database.transaction(function(tx) {
349: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
350: });
351: }
1.155 ihickson 352: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 353: mechanism and opens the local database (which, we presume, has been
354: created earlier). The worker then just listens for messages from the
355: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 356: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 357: this example online</a>. (This example will not actually function,
358: since the server does not actually exist and the database is not
1.155 ihickson 359: 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 360: fetching stock updates for at regular intervals, and one for
1.155 ihickson 361: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 362: <html>
363: <head>
364: <title>Worker example: Stock ticker</title>
365: <script>
1.33 ihickson 366: // TICKER
367: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 368: var ticker = new Worker('ticker.js');
1.33 ihickson 369:
370: // SEARCHER
1.50 ihickson 371: var searcher = new Worker('searcher.js');
1.33 ihickson 372: function search(query) {
1.50 ihickson 373: searcher.postMessage(query);
1.33 ihickson 374: }
375:
376: // SYMBOL SELECTION UI
377: function select(newSymbol) {
378: symbol = newSymbol;
1.50 ihickson 379: ticker.postMessage(symbol);
1.33 ihickson 380: }
1.81 ihickson 381: </script>
382: </head>
1.122 ihickson 383: <body onload="search('')">
1.81 ihickson 384: <p><output id="symbol"></output> <output id="value"></output></p>
385: <script>
1.50 ihickson 386: ticker.onmessage = function (event) {
1.54 ihickson 387: var data = event.data.split(' ');
1.33 ihickson 388: document.getElementById('symbol').textContent = data[0];
389: document.getElementById('value').textContent = data[1];
390: };
1.50 ihickson 391: ticker.postMessage(symbol);
1.81 ihickson 392: </script>
1.122 ihickson 393: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 394: <ul id="results"></ul>
395: <script>
1.50 ihickson 396: searcher.onmessage = function (event) {
1.54 ihickson 397: var data = event.data.split(' ');
1.33 ihickson 398: var results = document.getElementById('results');
399: while (results.hasChildNodes()) // clear previous results
400: results.removeChild(results.firstChild);
401: for (var i = 0; i < data.length; i += 1) {
402: // add a list item with a button for each result
403: var li = document.createElement('li');
404: var button = document.createElement('button');
405: button.value = data[i];
406: button.type = 'button';
407: button.onclick = function () { select(this.value); };
408: button.textContent = data[i];
409: li.appendChild(button);
410: results.appendChild(li);
411: }
412: };
1.81 ihickson 413: </script>
414: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
415: </body>
1.155 ihickson 416: </html></pre><p>The two workers use a common library for performing the actual
417: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 418: try {
419: var xhr = new XMLHttpRequest();
420: xhr.open('GET', url, false);
421: xhr.send();
422: return xhr.responseText;
423: } catch (e) {
424: return ''; // turn all errors into empty results
425: }
1.155 ihickson 426: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 427: var timer;
428: var symbol;
429: function update() {
1.50 ihickson 430: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 431: timer = setTimeout(update, 10000);
432: }
1.50 ihickson 433: onmessage = function (event) {
1.33 ihickson 434: if (timer)
435: clearTimeout(timer);
1.54 ihickson 436: symbol = event.data;
1.33 ihickson 437: update();
1.155 ihickson 438: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 439: onmessage = function (event) {
1.54 ihickson 440: postMessage(get('search.cgi?' + event.data));
1.155 ihickson 441: };</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 442: are all viewing the same map. All the windows share the same map
443: information, with a single worker coordinating all the viewers. Each
444: viewer can move around independently, but if they set any data on
1.155 ihickson 445: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
446: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 447: <html>
448: <head>
449: <title>Workers example: Multiviewer</title>
450: <script>
1.36 ihickson 451: function openViewer() {
452: window.open('viewer.html');
453: }
1.81 ihickson 454: </script>
455: </head>
456: <body>
457: <p><button type=button onclick="openViewer()">Open a new
458: viewer</button></p>
459: <p>Each viewer opens in a new window. You can have as many viewers
460: as you like, they all view the same data.</p>
461: </body>
1.155 ihickson 462: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 463: <html>
464: <head>
465: <title>Workers example: Multiviewer viewer</title>
466: <script>
1.50 ihickson 467: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 468:
469: // CONFIGURATION
470: function configure(event) {
1.54 ihickson 471: if (event.data.substr(0, 4) != 'cfg ') return;
472: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 473: // update display to mention our name is name
474: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
475: // no longer need this listener
1.43 ihickson 476: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 477: }
1.53 ihickson 478: worker.port.addEventListener('message', configure, false);
1.36 ihickson 479:
480: // MAP
481: function paintMap(event) {
1.54 ihickson 482: if (event.data.substr(0, 4) != 'map ') return;
483: var data = event.data.substr(4).split(',');
1.36 ihickson 484: // display tiles data[0] .. data[8]
485: var canvas = document.getElementById('map');
486: var context = canvas.getContext('2d');
487: for (var y = 0; y < 3; y += 1) {
488: for (var x = 0; x < 3; x += 1) {
489: var tile = data[y * 3 + x];
490: if (tile == '0')
491: context.fillStyle = 'green';
492: else
493: context.fillStyle = 'maroon';
494: fillRect(x * 50, y * 50, 50, 50);
495: }
496: }
497: }
1.53 ihickson 498: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 499:
500: // PUBLIC CHAT
501: function updatePublicChat(event) {
1.54 ihickson 502: if (event.data.substr(0, 4) != 'txt ') return;
503: var name = event.data.substr(4).split(' ', 1);
504: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 505: // display "<name> message" in public chat
1.36 ihickson 506: var dialog = document.getElementById('public');
507: var dt = document.createElement('dt');
508: dt.textContent = name;
509: dialog.appendChild(dt);
510: var dd = document.createElement('dd');
511: dd.textContent = message;
512: dialog.appendChild(dd);
513: }
1.53 ihickson 514: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 515:
516: // PRIVATE CHAT
517: function startPrivateChat(event) {
1.54 ihickson 518: if (event.data.substr(0, 4) != 'msg ') return;
519: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 520: var port = event.ports[0];
1.36 ihickson 521: // display a private chat UI
522: var ul = document.getElementById('private');
523: var li = document.createElement('li');
524: var h3 = document.createElement('h3');
525: h3.textContent = 'Private chat with ' + name;
526: li.appendChild(h3);
527: var dialog = document.createElement('dialog');
528: var addMessage = function(name, message) {
529: var dt = document.createElement('dt');
530: dt.textContent = name;
531: dialog.appendChild(dt);
532: var dd = document.createElement('dd');
533: dd.textContent = message;
534: dialog.appendChild(dd);
535: };
536: port.onmessage = function (event) {
1.54 ihickson 537: addMessage(name, event.data);
1.36 ihickson 538: };
539: li.appendChild(dialog);
540: var form = document.createElement('form');
541: var p = document.createElement('p');
542: var input = document.createElement('input');
543: input.size = 50;
544: p.appendChild(input);
545: p.appendChild(document.createTextNode(' '));
546: var button = document.createElement('button');
547: button.textContent = 'Post';
548: p.appendChild(button);
549: form.onsubmit = function () {
550: port.postMessage(input.value);
551: addMessage('me', input.value);
552: input.value = '';
553: return false;
554: };
555: form.appendChild(p);
556: li.appendChild(form);
557: }
1.53 ihickson 558: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 559:
560: worker.port.start();
1.81 ihickson 561: </script>
562: </head>
563: <body>
564: <h1>Viewer</h1>
565: <h2>Map</h2>
566: <p><canvas id="map" height=150 width=150></canvas></p>
567: <p>
568: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
569: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
570: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
571: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
572: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
573: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
574: </p>
575: <h2>Public Chat</h2>
576: <dialog id="public"></dialog>
577: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
578: <p>
579: <input type="text" name="message" size="50">
580: <button>Post</button>
581: </p>
582: </form>
583: <h2>Private Chat</h2>
584: <ul id="private"></ul>
585: </body>
586: </html>
1.155 ihickson 587: </pre><p>There are several key things worth noting about the way the
588: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 589: processing function, the code here attaches multiple event
590: listeners, each one performing a quick check to see if it is
591: relevant for the message. In this example it doesn't make much
592: difference, but if multiple authors wanted to collaborate using a
593: single port to communicate with a worker, it would allow for
594: independent code instead of changes having to all be made to a
1.155 ihickson 595: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 596: unregister specific listeners when you are done with them, as is
597: done with the <code title="">configure()</code> method in this
1.155 ihickson 598: example.<p>Finally, the worker:<pre>
599: var nextName = 0;
1.36 ihickson 600: function getNextName() {
601: // this could use more friendly names
602: // but for now just return a number
603: return nextName++;
604: }
605:
606: var map = [
607: [0, 0, 0, 0, 0, 0, 0],
608: [1, 1, 0, 1, 0, 1, 1],
609: [0, 1, 0, 1, 0, 0, 0],
610: [0, 1, 0, 1, 0, 1, 1],
611: [0, 0, 0, 1, 0, 0, 0],
612: [1, 0, 0, 1, 1, 1, 1],
613: [1, 1, 0, 1, 1, 0, 1],
614: ];
615:
616: function wrapX(x) {
617: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 618: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 619: return x;
620: }
621:
622: function wrapY(y) {
623: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 624: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 625: return y;
626: }
627:
1.50 ihickson 628: function sendMapData(callback) {
1.36 ihickson 629: var data = '';
630: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
631: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
632: if (data != '')
633: data += ',';
634: data += map[y][x];
635: }
636: }
1.50 ihickson 637: callback('map ' + data);
1.36 ihickson 638: }
639:
640: var viewers = {};
641: onconnect = function (event) {
1.84 ihickson 642: event.ports[0]._name = getNextName();
643: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
644: viewers[event.ports[0]._name] = event.port._data;
645: event.ports[0].postMessage('cfg ' + name);
646: event.ports[0].onmessage = getMessage;
647: sendMapData(event.ports[0].postMessage);
1.36 ihickson 648: };
649:
650: function getMessage(event) {
1.54 ihickson 651: switch (event.data.substr(0, 4)) {
1.36 ihickson 652: case 'mov ':
1.54 ihickson 653: var direction = event.data.substr(4);
1.36 ihickson 654: var dx = 0;
655: var dy = 0;
656: switch (direction) {
657: case 'up': dy = -1; break;
658: case 'down': dy = 1; break;
659: case 'left': dx = -1; break;
660: case 'right': dx = 1; break;
661: }
662: event.target._data.x = wrapX(event.target._data.x + dx);
663: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 664: sendMapData(event.target.postMessage);
1.36 ihickson 665: break;
666: case 'set ':
1.54 ihickson 667: var value = event.data.substr(4);
1.36 ihickson 668: map[event.target._data.y][event.target._data.x] = value;
669: for (var viewer in viewers)
1.50 ihickson 670: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 671: break;
672: case 'txt ':
673: var name = event.target._name;
1.54 ihickson 674: var message = event.data.substr(4);
1.36 ihickson 675: for (var viewer in viewers)
676: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
677: break;
678: case 'msg ':
679: var party1 = event._data;
1.54 ihickson 680: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 681: if (party2) {
682: var channel = new MessageChannel();
1.84 ihickson 683: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
684: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 685: }
686: break;
687: }
1.155 ihickson 688: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 689: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 690: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 691: "msg" message from one viewer naming another viewer, it sets up a
692: direct connection between the two, so that the two viewers can
693: communicate directly without the worker having to proxy all the
1.155 ihickson 694: 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 695: performance is to split computationally expensive tasks amongst
696: multiple workers. In this example, a computationally expensive task
697: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 698: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 699: <html>
700: <head>
701: <title>Worker example: One-core computation</title>
702: </head>
703: <body>
704: <p>The highest prime number discovered so far is: <output id="result"></output></p>
705: <script>
1.50 ihickson 706: var worker = new Worker('worker.js');
707: worker.onmessage = function (event) {
1.54 ihickson 708: document.getElementById('result').textContent = event.data;
1.40 ihickson 709: };
1.81 ihickson 710: </script>
711: </body>
1.155 ihickson 712: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 713: var num_workers = 10;
714: var items_per_worker = 1000000;
715:
716: // start the workers
717: var result = 0;
718: var pending_workers = num_workers;
719: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 720: var worker = new Worker('core.js');
721: worker.postMessage(i * items_per_worker);
722: worker.postMessage((i+1) * items_per_worker);
723: worker.onmessage = storeResult;
1.40 ihickson 724: }
725:
726: // handle the results
727: function storeResult(event) {
1.54 ihickson 728: result += 1*event.data;
1.40 ihickson 729: pending_workers -= 1;
730: if (pending_workers <= 0)
1.50 ihickson 731: postMessage(result); // finished!
1.155 ihickson 732: }</pre><p>It consists of a loop to start the subworkers, and then a handler
733: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 734: onmessage = getStart;
1.40 ihickson 735: function getStart(event) {
1.54 ihickson 736: start = 1*event.data;
1.40 ihickson 737: onmessage = getEnd;
738: }
739:
740: var end;
741: function getEnd(event) {
1.54 ihickson 742: end = 1*event.data;
1.40 ihickson 743: onmessage = null;
1.66 ihickson 744: work();
1.40 ihickson 745: }
746:
1.66 ihickson 747: function work() {
1.40 ihickson 748: var result = 0;
749: for (var i = start; i < end; i += 1) {
750: // perform some complex calculation here
751: result += 1;
752: }
1.50 ihickson 753: postMessage(result);
754: close();
1.155 ihickson 755: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 756: for the range of numbers thus specified, and then report the result
1.155 ihickson 757: 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
758: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 759:
760: <dd>Takes a port, on which it will send two messages, first the
761: public key and then the private key.</dd>
762:
763: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
764:
765: <dd>Takes a port, to which any number of messages can be sent, the
766: first giving the public key, and the remainder giving the
767: plaintext, each of which is encrypted and then sent on that same
768: channel as the cyphertext. The user can close the port when it is
769: done encrypting content.</dd>
770:
771: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
772:
773: <dd>Takes a port, to which any number of messages can be sent, the
774: first giving the private key, and the remainder giving the
775: cyphertext, each of which is decrypted and then sent on that same
776: channel as the plaintext. The user can close the port when it is
777: done decrypting content.</dd>
1.49 ihickson 778:
1.155 ihickson 779: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 780: if (e.data == "genkeys")
1.84 ihickson 781: genkeys(e.ports[0]);
1.54 ihickson 782: else if (e.data == "encrypt")
1.84 ihickson 783: encrypt(e.ports[0]);
1.54 ihickson 784: else if (e.data == "decrypt")
1.84 ihickson 785: decrypt(e.ports[0]);
1.49 ihickson 786: }
787:
788: function genkeys(p) {
789: var keys = _generateKeyPair();
790: p.postMessage(keys[0]);
791: p.postMessage(keys[1]);
792: }
793:
794: function encrypt(p) {
795: var key, state = 0;
796: p.onmessage = function (e) {
797: if (state == 0) {
1.54 ihickson 798: key = e.data;
1.49 ihickson 799: state = 1;
800: } else {
1.54 ihickson 801: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 802: }
803: };
804: }
805:
806: function decrypt(p) {
807: var key, state = 0;
808: p.onmessage = function (e) {
809: if (state == 0) {
1.54 ihickson 810: key = e.data;
1.49 ihickson 811: state = 1;
812: } else {
1.54 ihickson 813: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 814: }
815: };
816: }
817:
1.50 ihickson 818: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 819: if ('onmessage' in this) // dedicated worker
1.50 ihickson 820: onmessage = handleMessage;
821: else // shared worker
822: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 823:
824:
825: // the "crypto" functions:
826:
827: function _generateKeyPair() {
828: return [Math.random(), Math.random()];
829: }
830:
831: function _encrypt(k, s) {
832: return 'encrypted-' + k + ' ' + s;
833: }
834:
835: function _decrypt(k, s) {
836: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 837: }</pre><p>Note that the crypto functions here are just stubs and don't do
838: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 839: <html>
840: <head>
841: <title>Worker example: Crypto library</title>
842: <script>
1.50 ihickson 843: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 844: function getKeys() {
845: var state = 0;
1.50 ihickson 846: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 847: if (state == 0)
1.54 ihickson 848: document.getElementById('public').value = e.data;
1.49 ihickson 849: else if (state == 1)
1.54 ihickson 850: document.getElementById('private').value = e.data;
1.49 ihickson 851: state += 1;
852: };
853: }
854: function enc() {
1.50 ihickson 855: var port = cryptoLib.startConversation("encrypt");
856: port.postMessage(document.getElementById('public').value);
857: port.postMessage(document.getElementById('input').value);
858: port.onmessage = function (e) {
1.54 ihickson 859: document.getElementById('input').value = e.data;
1.50 ihickson 860: port.close();
1.49 ihickson 861: };
862: }
863: function dec() {
1.50 ihickson 864: var port = cryptoLib.startConversation("decrypt");
865: port.postMessage(document.getElementById('private').value);
866: port.postMessage(document.getElementById('input').value);
867: port.onmessage = function (e) {
1.54 ihickson 868: document.getElementById('input').value = e.data;
1.50 ihickson 869: port.close();
1.49 ihickson 870: };
871: }
1.81 ihickson 872: </script>
873: <style>
1.49 ihickson 874: textarea { display: block; }
1.81 ihickson 875: </style>
876: </head>
877: <body onload="getKeys()">
878: <fieldset>
879: <legend>Keys</legend>
880: <p><label>Public Key: <textarea id="public"></textarea></label></p>
881: <p><label>Private Key: <textarea id="private"></textarea></label></p>
882: </fieldset>
883: <p><label>Input: <textarea id="input"></textarea></label></p>
884: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
885: </body>
1.155 ihickson 886: </html></pre><p>A later version of the API, though, might want to offload all the
887: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 888: if (e.data == "genkeys")
1.84 ihickson 889: genkeys(e.ports[0]);
1.54 ihickson 890: else if (e.data == "encrypt")
1.84 ihickson 891: encrypt(e.ports[0]);
1.54 ihickson 892: else if (e.data == "decrypt")
1.84 ihickson 893: decrypt(e.ports[0]);
1.49 ihickson 894: }
895:
896: function genkeys(p) {
1.50 ihickson 897: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 898: generator.postMessage('', [p]);
1.49 ihickson 899: }
900:
901: function encrypt(p) {
902: p.onmessage = function (e) {
1.54 ihickson 903: var key = e.data;
1.50 ihickson 904: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 905: encryptor.postMessage(key, [p]);
1.49 ihickson 906: };
907: }
908:
909: function encrypt(p) {
910: p.onmessage = function (e) {
1.54 ihickson 911: var key = e.data;
1.50 ihickson 912: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 913: decryptor.postMessage(key, [p]);
1.49 ihickson 914: };
915: }
916:
1.50 ihickson 917: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 918: if ('onmessage' in this) // dedicated worker
1.50 ihickson 919: onmessage = handleMessage;
920: else // shared worker
1.84 ihickson 921: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 922: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 923: var k = _generateKeyPair();
1.84 ihickson 924: e.ports[0].postMessage(k[0]);
925: e.ports[0].postMessage(k[1]);
1.49 ihickson 926: close();
927: }
1.50 ihickson 928:
929: function _generateKeyPair() {
930: return [Math.random(), Math.random()];
1.155 ihickson 931: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 932: var key = e.data;
1.84 ihickson 933: e.ports[0].onmessage = function (e) {
1.54 ihickson 934: var s = e.data;
1.50 ihickson 935: postMessage(_encrypt(key, s));
1.49 ihickson 936: }
1.50 ihickson 937: }
938:
939: function _encrypt(k, s) {
940: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 941: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 942: var key = e.data;
1.84 ihickson 943: e.ports[0].onmessage = function (e) {
1.54 ihickson 944: var s = e.data;
1.50 ihickson 945: postMessage(_decrypt(key, s));
1.49 ihickson 946: }
1.50 ihickson 947: }
948:
949: function _decrypt(k, s) {
950: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 951: }</pre><p>Notice how the users of the API don't have to even know that this
952: is happening — the API hasn't changed; the library can
1.81 ihickson 953: delegate to subworkers without changing its API, even though it is
1.155 ihickson 954: 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 955: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 956: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 957: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
958: "OPTIONAL" in the normative parts of this document are to be
959: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 960: 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 961: (such as "strip any leading space characters" or "return false and
962: abort these steps") are to be interpreted with the meaning of the
963: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 964: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 965: attributes, methods or objects. Such requirements are to be
1.155 ihickson 966: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 967: may be implemented in any manner, so long as the end result is
968: equivalent. (In particular, the algorithms defined in this
969: specification are intended to be easy to follow, and not intended to
1.155 ihickson 970: be performant.)<p>The only conformance class defined by this specification is user
971: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 972: otherwise unconstrained inputs, e.g. to prevent denial of service
973: attacks, to guard against running out of memory, or to work around
1.155 ihickson 974: platform-specific limitations.<h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3><p>This specification relies on several other underlying
975: specifications.<dl><dt>HTML5</dt>
1.49 ihickson 976:
1.81 ihickson 977: <dd>
1.49 ihickson 978:
1.81 ihickson 979: <p>Many fundamental concepts from HTML5 are used by this
1.152 ihickson 980: specification. <a href="#refsHTML5">[HTML5]</a></p>
1.49 ihickson 981:
1.81 ihickson 982: </dd>
1.1 ihickson 983:
1.81 ihickson 984: <dt>WebIDL</dt>
1.1 ihickson 985:
986: <dd>
987:
1.81 ihickson 988: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 989: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 990:
1.81 ihickson 991: </dd>
1.1 ihickson 992:
1.155 ihickson 993: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 994: <code title="">Foo</code> is actually an interface, is sometimes
995: used instead of the more accurate "an object implementing the
1.155 ihickson 996: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 997: scripts in Web applications, and does not necessarily imply the
998: existence of an actual <code>Document</code> object or of any other
999: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 1000: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1001: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1002: <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 1003: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1004: 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 1005: workers. Dedicated workers, once created, and are linked to their
1006: creator; but message ports can be used to communicate from a
1007: dedicated worker to multiple other browsing contexts or
1008: workers. Shared workers, on the other hand, are named, and once
1009: created any script running in the same <span>origin</span> can
1.155 ihickson 1010: 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 1011: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1012: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1013:
1014: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1015: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1016: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1017: };
1.172 ihickson 1018: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
1019: <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 1020: 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 1021: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1022: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1023: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1024: 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 1025: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1026: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1027: have been added to the <span>event loop</span>'s <span title="task
1028: queue">task queues</span>.</p>
1029:
1030: <!-- v2-onclose
1031: <li><p><span>Queue a task</span> to <span>fire a simple
1.179 ihickson 1032: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1033: <code>WorkerGlobalScope</code> object.</p></li>
1034: -->
1.81 ihickson 1035:
1.115 ihickson 1036: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1037: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1038: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1039:
1.124 ihickson 1040: <li><p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1.123 ihickson 1041: ports</a>.</li>
1.81 ihickson 1042:
1.177 ihickson 1043: </ol><p>The following are the <span>event handlers</span> (and their
1044: corresponding <span title="event handler event type">event handler
1045: event types</span>) that must be supported, as IDL attributes, by
1046: objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1047: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1048: <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>
1049: </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 1050: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.174 ihickson 1051: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.77 ihickson 1052: <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1053: attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1054: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1055: had an implicit <code>MessagePort</code> associated with them. This
1056: port is part of a channel that is set up when the worker is created,
1057: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1058: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1059: 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 1060: and <dfn
1061: title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
1.81 ihickson 1062: method<!--s (startConversation)--> on
1.115 ihickson 1063: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.81 ihickson 1064: invoked, it<!--/they (startConversation)--> immediately invoked the
1065: method of the same name on the port, with the same arguments, and
1.177 ihickson 1066: returned the same return value.<p>The following are the <span>event handlers</span> (and their
1067: corresponding <span title="event handler event type">event handler
1068: event types</span>) that must be supported, as IDL attributes, by
1069: objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1070: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1071: <tbody><tr><td><dfn id="handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1.191 ihickson 1072: </table><p>For the purposes of the <span>application cache</span> networking
1073: model, a dedicated worker is an extension of the <span>cache
1074: 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 1075: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1076: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1077: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.144 ihickson 1078: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1079: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1080: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1081: attribute must return the value it was assigned when the
1.115 ihickson 1082: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1083: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1084: that can be used to obtain a reference to the worker using the
1.177 ihickson 1085: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handlers</span> (and their
1086: corresponding <span title="event handler event type">event handler
1087: event types</span>) that must be supported, as IDL attributes, by
1088: objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1089: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1090: <tbody><tr><td><dfn id="handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect"><code>onconnect</code></dfn> <td> <code title="event-connect">connect</code>
1.191 ihickson 1091: </table><p>For the purposes of the <span>application cache</span> networking
1092: model, a shared worker is its own <span>cache host</span>. The
1093: <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1094: worker with an <span>application cache</span>.<p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
1.123 ihickson 1095: attribute returns the <code>ApplicationCache</code> object for the
1.101 ihickson 1096: worker.</p><!-- normative conf criteria is in the appcache section
1.160 ihickson 1097: --><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 1098: origin</span> of scripts running in workers are the
1099: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1100: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.186 ihickson 1101: represents.<h3 id="the-event-loop"><span class="secno">4.3 </span>The event loop</h3><p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object has an <span>event
1.128 ihickson 1102: loop</span> distinct from those defined for <span title="unit of
1103: related similar-origin browsing contexts">units of related
1104: similar-origin browsing contexts</span>. This <span>event
1105: loop</span> has no associated <span>browsing context</span>, and its
1106: <span title="task queue">task queues</span> only have events,
1107: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1108: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1109: <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 1110: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1111: 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 1112: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1113: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1114: already on the queue are unaffected except where otherwise
1.115 ihickson 1115: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1116: timers stop firing, notifications for all pending asynchronous
1.186 ihickson 1117: operations are dropped, etc.<h3 id="the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</h3><p>Workers communicate with other workers and with <span title="browsing context">browsing contexts</span> through <span title="channel messaging">message channels</span> and their
1.155 ihickson 1118: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1119: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1120: consists of all the <code>MessagePort</code> objects that are
1121: entangled with another port and that have one (but only one) port
1122: owned by <var title="">worker global scope</var>. This list includes
1123: <!--all the <code>MessagePort</code> objects that are in events
1.68 ihickson 1124: pending in the <span>event loop</span>, as well as (commented out
1125: because in practice it makes no difference either way as far as I
1126: can tell, and it would be hard to strictly implement since these
1.81 ihickson 1127: ports might not yet be across the thread boundary)--> the implicit
1.155 ihickson 1128: <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 1129: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1130: 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 1131: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1132: 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 1133: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1134: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1135: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1136: <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 1137: documents">add <var title="">d</var> to <var title="">q</var>'s
1138: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.155 ihickson 1139: <code>Document</code>s</span></a>.</p><!-- suggestions welcome
1140: on making this sentence into understandable English --><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1141: Document">discarded</span>, it must be removed from the list of
1142: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.192 ihickson 1143: whose list contains that <code>Document</code>.<p>Given a <span>script's global object</span> <var title="">o</var>
1.123 ihickson 1144: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1145: <code>Document</code> objects to add</dfn> depends on the type of
1146: <var title="">o</var>. If <var title="">o</var> is a
1147: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1148: nested worker), then the relevant <code>Document</code>s are the
1149: <code>Document</code>s that are in <var title="">o</var>'s own list
1150: 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
1151: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1152: <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 1153: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1154: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1155: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1156: timers, database transactions, or network connections, or its list
1.124 ihickson 1157: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1158: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1159: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1160: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1161: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1162: <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 1163: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.186 ihickson 1164: <a href="#permissible-worker">permissible worker</a>.<h3 id="processing-model"><span class="secno">4.5 </span>Processing model</h3><p>When a user agent is to <dfn id="run-a-worker">run a worker</dfn> for a script with
1.176 ihickson 1165: <span>URL</span> <var title="">url</var>, a browsing context <var title="">owner browsing context</var>, an origin <var title="">owner
1166: origin</var>, and with global scope <var title="">worker global
1167: scope</var>, it must run the following steps:<ol><li>
1.81 ihickson 1168:
1169: <p>Create a completely separate and parallel execution environment
1170: (i.e. a separate thread or process or equivalent construct), and
1.106 ihickson 1171: run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1172:
1173: </li>
1.4 ihickson 1174:
1.101 ihickson 1175: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1176: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1177: shared worker), and there are any <span title="relevant application
1178: cache">relevant application caches</span> that are identified by a
1179: 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 1180: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1181: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1182: cache</span> of those that match.</li>
1183:
1.4 ihickson 1184: <li>
1.52 ihickson 1185:
1.176 ihickson 1186: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>.</p>
1187: <!-- not http-origin privacy sensitive -->
1.81 ihickson 1188:
1.129 ihickson 1189: <p>If the attempt fails, or if the attempt involves any redirects
1190: 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
1191: origin</span> as the original <var title="">url</var>), then for
1192: each <code><a href="#worker">Worker</a></code> or <code><a href="#sharedworker">SharedWorker</a></code> object
1193: associated with <var title="">worker global scope</var>,
1194: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1195: named <code title="event-error">error</code> at that
1.129 ihickson 1196: object. Abort these steps.</p>
1.7 ihickson 1197:
1.186 ihickson 1198: <p>If the attempt succeeds, then convert the script resource to
1199: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.81 ihickson 1200:
1.68 ihickson 1201: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1202:
1.115 ihickson 1203: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1204: type of the script is ignored. Unlike with <code>script</code>
1205: elements, there is no way to override the type. It's always
1.170 ihickson 1206: assumed to be JavaScript.</p>
1.81 ihickson 1207:
1208: </li>
1.7 ihickson 1209:
1210: <li>
1.68 ihickson 1211:
1.115 ihickson 1212: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1213: created, as follows.</p>
1214:
1215: <p>Create a new <span>script execution environment</span>
1216: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1217:
1.68 ihickson 1218: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1219: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1220: entry-points</span>; set the <i>initial code entry-point</i> to
1221: the entry-point for any executable code to be immediately run.</p>
1222:
1223: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1224:
1225: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1226:
1.83 ihickson 1227: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1228: UTF-8. (This is just used for encoding non-ASCII characters in the
1229: query component of URLs.)</p>
1.68 ihickson 1230:
1231: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1232:
1.81 ihickson 1233: </li>
1.4 ihickson 1234:
1235: <li>
1.81 ihickson 1236:
1237: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1238: worker such that no sooner than it stops being either a
1239: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1240: worker</a>, and no later than it stops being a
1241: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1242: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1243: to true<!-- v2-onclose and <span title="queue a task">a task is
1.179 ihickson 1244: queued</span> to <span>fire a simple event</span> named <code
1.123 ihickson 1245: title="event-close">close</code> at <var title="">worker global
1246: scope</var>-->.</p>
1.81 ihickson 1247:
1248: </li>
1.9 ihickson 1249:
1250: <li>
1.7 ihickson 1251:
1.81 ihickson 1252: <p><strong>Suspending workers</strong>: Start monitoring the
1253: worker, such that whenever <var title="">worker global
1.115 ihickson 1254: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1255: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1256: agent suspends execution of script in that worker until such time
1.115 ihickson 1257: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1258: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1259: worker</a>.</p>
1.4 ihickson 1260:
1.81 ihickson 1261: </li>
1.68 ihickson 1262:
1263: <li>
1.4 ihickson 1264:
1.81 ihickson 1265: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1266: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1267: entry-point</i>, and let that run until it either returns, fails
1268: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1269: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1270: algorithms defined below.</p>
1271:
1.149 ihickson 1272: <!-- v2-onclose
1273: <p class="note">If the script gets aborted by the "<span>kill a
1274: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1275: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1276: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1277: for the <code title="message-close">close</code> event. The
1.149 ihickson 1278: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1279: events.</p>
1.149 ihickson 1280: -->
1.4 ihickson 1281:
1.81 ihickson 1282: </li>
1.4 ihickson 1283:
1.95 ihickson 1284: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1285: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1286: a dedicated worker), then enable the <span>port message
1287: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1288:
1.4 ihickson 1289: <li>
1.68 ihickson 1290:
1.115 ihickson 1291: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1292: 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 1293: to true.</p>
1.43 ihickson 1294:
1.81 ihickson 1295: </li>
1.4 ihickson 1296:
1297: <li>
1298:
1.81 ihickson 1299: <p>Run the oldest task on one of the <span>event loop</span>'s
1300: <span title="task queue">task queues</span>, if any. The user
1301: agent may pick any <span>task queue</span>.</p>
1302:
1.115 ihickson 1303: <p class="note">The handling of events or the execution of
1304: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1305: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1306: defined below.</p>
1.8 ihickson 1307:
1.81 ihickson 1308: </li>
1.4 ihickson 1309:
1310: <li>
1311:
1.81 ihickson 1312: <p>Remove the task run in the previous step, if any, from its
1313: <span>task queue</span>.</p>
1.4 ihickson 1314:
1.81 ihickson 1315: </li>
1.4 ihickson 1316:
1317: <li>
1.8 ihickson 1318:
1.81 ihickson 1319: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1320: <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 1321: to false, then jump back to the step above labeled <i>event
1322: loop</i>.</p>
1.8 ihickson 1323:
1.81 ihickson 1324: </li>
1.8 ihickson 1325:
1326: <li>
1.71 ihickson 1327:
1.123 ihickson 1328: <p>If there are any outstanding transactions that have callbacks
1329: that involve <span title="concept-script">scripts</span> whose
1330: <span title="script's global object">global object</span> is the
1331: <var title="">worker global scope</var>, roll them back (without
1332: invoking any of the callbacks).</p>
1.50 ihickson 1333:
1.123 ihickson 1334: </li>
1335:
1336: <li>
1337:
1338: <p>Empty the <var title="">worker global scope</var>'s <span>list
1339: of active timeouts</span> and its <span>list of active
1340: intervals</span>.</p>
1.50 ihickson 1341:
1.81 ihickson 1342: </li>
1.50 ihickson 1343:
1.123 ihickson 1344: <!-- v2-onclose
1.81 ihickson 1345: <li>
1.50 ihickson 1346:
1.123 ihickson 1347: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1348: object associated with <var title="">worker global scope</var>,
1349: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1350: named <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1351:
1.81 ihickson 1352: </li>
1.123 ihickson 1353: -->
1.155 ihickson 1354: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1355: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1356: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1357: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1358: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1359: false, <span>queue a task</span> to <span>fire a simple
1.179 ihickson 1360: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1361: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1362: --><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 1363: true.</li>
1364:
1.123 ihickson 1365: <!-- v2-onclose
1366: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1367: a worker</span>" processing model defined above immediately starts
1368: running event listeners registered for the <code
1369: title="event-close">close</code> event, this time should not be
1370: zero — the idea is that the <code
1371: title="event-close">close</code> event can be used to clean up
1372: when shutting down unexpectedly.</p></li>
1373: -->
1.81 ihickson 1374:
1.115 ihickson 1375: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1376: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1377: queue">task queues</span><!-- v2-onclose other than the <code
1378: title="event-close">close</code> event that this algorithm just
1379: added-->, discard them without processing them.</li>
1.81 ihickson 1380:
1.123 ihickson 1381: <!-- v2-onclose
1.115 ihickson 1382: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1383: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1384: the script currently running in the worker.</p></li>
1385: -->
1.81 ihickson 1386:
1387: <li><p>Wait a user-agent-defined amount of time.</li>
1388:
1.123 ihickson 1389: <li><p>Abort the script currently running in the worker<!--
1390: v2-onclose (if any script is running, then it will be a handler for
1391: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1392:
1.155 ihickson 1393: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1394: processing model on a worker at any time, e.g. in response to user
1395: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1396: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1397: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1398: 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 1399: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1400: "<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 1401: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1402: true.</li>
1403:
1.115 ihickson 1404: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1405: queued in the <span>event loop</span>'s <span title="task
1406: queue">task queues</span>, discard them without processing
1407: them.</li>
1408:
1409: <li><p>Abort the script currently running in the worker.</li>
1410:
1.115 ihickson 1411: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1412: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1413: worker is a dedicated worker), then empty the <span>port message
1414: queue</span> of the port that the worker's implicit port is
1415: entangled with.</li>
1416:
1.155 ihickson 1417: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.186 ihickson 1418: <span>DOM manipulation task source</span>.<h3 id="runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</h3><p>Whenever an uncaught runtime script error occurs in one of the
1.143 ihickson 1419: worker's scripts, if the error did not occur while handling a
1420: previous script error, the user agent must <span>report the
1421: 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 1422: 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 1423: the error occurred while handling a previous script error, the error
1.155 ihickson 1424: 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 1425: the error occurred while handling a previous script error, the user
1.123 ihickson 1426: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1427: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1428: 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 1429: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1430: 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 1431: 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 1432: appropriately. The default action of this event depends on whether
1.115 ihickson 1433: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1434: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1435: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1436: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1437: <em>that</em> worker. Otherwise, then the error should be reported
1.155 ihickson 1438: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1439: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : Event {
1.147 ihickson 1440: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1441: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1442: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1443: void <a href="#dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent">initErrorEvent</a>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString messageArg, in DOMString filenameArg, in unsigned long linenoArg);
1.155 ihickson 1444: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.190 ihickson 1445: method must initialize the event in a manner analogous to the
1446: similarly-named method in the DOM Events interfaces. <a href="#refsDOMEVENTS">[DOMEVENTS]</a><p>The <dfn id="dom-errorevent-message" title="dom-ErrorEvent-message"><code>message</code></dfn>
1.155 ihickson 1447: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1448: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1449: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1450: attribute represents the line number where the error occurred in the
1.186 ihickson 1451: script.<h3 id="creating-workers"><span class="secno">4.7 </span>Creating workers</h3><h4 id="the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code><a href="#abstractworker">AbstractWorker</a></code> abstract interface</h4><pre class="idl">interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1452: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1453: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.172 ihickson 1454: };
1.177 ihickson 1455: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handlers</span> (and their
1456: corresponding <span title="event handler event type">event handler
1457: event types</span>) that must be supported, as IDL attributes, by
1458: objects implementing the <code><a href="#abstractworker">AbstractWorker</a></code> interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1459: <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 1460: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.186 ihickson 1461: </table><h4 id="dedicated-workers-and-the-worker-interface"><span class="secno">4.7.2 </span>Dedicated workers and the <code><a href="#worker">Worker</a></code> interface</h4><pre class="idl">[<a href="#dom-worker" title="dom-Worker">Constructor</a>(in DOMString scriptURL)]
1.115 ihickson 1462: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1463: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1464:
1.174 ihickson 1465: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1466: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1467: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1468: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1469: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1470: algorithm to be run on the worker with with the object is
1.155 ihickson 1471: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1472: <code>MessagePort</code> associated with them. This port is part of
1473: a channel that is set up when the worker is created, but it is not
1474: exposed. This object must never be garbage collected before the
1.155 ihickson 1475: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1476: 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 1477: and <dfn
1478: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1479: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1480: must act as if, when invoked, it<!--/they (startConversation)-->
1481: immediately invoked the method of the same name on the port, with
1.177 ihickson 1482: the same arguments, and returned the same return value.<p>The following are the <span>event handlers</span> (and their
1483: corresponding <span title="event handler event type">event handler
1484: event types</span>) that must be supported, as IDL attributes, by
1485: objects implementing the <code><a href="#worker">Worker</a></code> interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1486: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1487: </table><hr><p>When the <dfn id="dom-worker" title="dom-Worker"><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
1488: 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 1489: script</span>'s <span title="script's base URL">base URL</span>,
1490: when the method is invoked.</li>
1.9 ihickson 1491:
1.81 ihickson 1492: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1493: exception.</li>
1.9 ihickson 1494:
1.167 ihickson 1495: <li>
1496:
1497: <p>If the <span>origin</span> of the resulting <span>absolute
1498: URL</span> is not the <span title="same origin">same</span> as the
1.176 ihickson 1499: origin of the <span>first script</span>, then throw a
1.182 ihickson 1500: <code>SECURITY_ERR</code> exception.</p>
1.167 ihickson 1501:
1502: <p class="note">Thus, scripts must be external files with the same
1503: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1504: URL, and a <code>http:</code> page couldn't start workers using
1505: scripts with <code>http:</code> URLs.</p>
1506:
1507: </li>
1.9 ihickson 1508:
1.185 ihickson 1509: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1510: object. Let <var title="">worker global scope</var> be this new
1511: object.</li>
1.9 ihickson 1512:
1.115 ihickson 1513: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1514: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1515:
1.185 ihickson 1516: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1517: owned by the <span title="script's global object">global
1518: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1519: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1520: port</var>.</li>
1.9 ihickson 1521:
1.81 ihickson 1522: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1523:
1.185 ihickson 1524: <li><p><span>Create a new <code>MessagePort</code> object</span>
1525: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1526:
1.81 ihickson 1527: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1528:
1.81 ihickson 1529: <li><p><span>Entangle</span> <var title="">outside port</var> and
1530: <var title="">inside port</var>.</li>
1.50 ihickson 1531:
1.81 ihickson 1532: <li><p>Return <var title="">worker</var>, and run the following
1533: steps asynchronously.</li>
1.50 ihickson 1534:
1.126 ihickson 1535: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.81 ihickson 1536: queue</span>.</li>
1.50 ihickson 1537:
1.126 ihickson 1538: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1539: queue</span>.</li>
1.50 ihickson 1540:
1541: <li>
1.51 ihickson 1542:
1.123 ihickson 1543: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1544: <code>Document</code> objects to add</a> given the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.123 ihickson 1545: constructor.</p>
1546:
1547: </li>
1548:
1549: <li>
1550:
1551: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1552: <var title="">worker global scope</var>'s list of <span>the
1553: worker's <code>Document</code>s</span></a> the
1554: <code>Document</code> objects in <var title="">docs</var>.</p>
1555:
1556: </li>
1557:
1558: <li>
1559:
1.192 ihickson 1560: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1561: of the <span title="concept-script">script</span> that invoked the
1562: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1563: are creating a nested worker), add <var title="">worker global
1564: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 1565: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object that is the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.124 ihickson 1566: constructor.</p>
1567:
1568: </li>
1569:
1570: <li>
1571:
1.115 ihickson 1572: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 1573: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 1574: script that invoked the method as the <var title="">owner browsing
1.176 ihickson 1575: context</var>, with the <span>origin</span> of the <span>first
1576: script</span> as the <var title="">owner origin</var>, and with
1577: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1578:
1.81 ihickson 1579: </li>
1.4 ihickson 1580:
1.155 ihickson 1581: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1582: object</span> is either a <code>Window</code> object or an object
1.186 ihickson 1583: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<h4 id="shared-workers-and-the-sharedworker-interface"><span class="secno">4.7.3 </span>Shared workers and the <code><a href="#sharedworker">SharedWorker</a></code> interface</h4><pre class="idl">[<a href="#dom-sharedworker" title="dom-SharedWorker">Constructor</a>(in DOMString scriptURL, in optional DOMString name)]
1.115 ihickson 1584: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1585: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1586: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1587: attribute must return the value it was assigned by the object's
1588: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1589: 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 1590: constructor is invoked, the user agent must run the following
1.155 ihickson 1591: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1592:
1593: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1594: exception.</li>
1595:
1.159 ihickson 1596: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1597: resulting <span>absolute URL</span>.</li>
1598:
1599: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1600: argument, or the empty string if the second argument was
1601: omitted.</li>
1.159 ihickson 1602:
1.167 ihickson 1603: <li>
1604:
1605: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1606: not the <span title="same origin">same</span> as the origin of the
1.182 ihickson 1607: <span>first script</span>, then throw a <code>SECURITY_ERR</code>
1608: exception.</p>
1.167 ihickson 1609:
1610: <p class="note">Thus, scripts must be external files with the same
1611: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1612: URL, and a <code>http:</code> page couldn't start workers using
1613: scripts with <code>http:</code> URLs.</p>
1614:
1615: </li>
1.9 ihickson 1616:
1617: <li>
1618:
1.123 ihickson 1619: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1620: <code>Document</code> objects to add</a> given the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.123 ihickson 1621: constructor.</p>
1622:
1623: </li>
1624:
1625: <li>
1626:
1.50 ihickson 1627: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1628:
1.155 ihickson 1629: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1630: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1631: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1632:
1.185 ihickson 1633: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1634: owned by the <span title="script's global object">global
1635: object</span> of the script that invoked the method. Let this be
1.123 ihickson 1636: the <var title="">outside port</var>.</li>
1.81 ihickson 1637:
1.115 ihickson 1638: <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 1639:
1.164 ihickson 1640: <li><p>Let <var title="">worker global scope</var> be
1641: null.</li>
1642:
1643: <li><p>If <var title="">name</var> is not the empty string and
1644: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1645: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1646: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1647: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1648: represents an <span>absolute URL</span> with the <span>same
1649: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1650: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1651:
1652: <li><p>Otherwise, if <var title="">name</var> is the empty string
1653: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1654: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1655: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1656: is exactly equal to <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1657: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1658:
1.9 ihickson 1659: <li>
1660:
1.164 ihickson 1661: <p>If <var title="">worker global scope</var> is not null, then
1662: run these steps:</p>
1.81 ihickson 1663:
1.164 ihickson 1664: <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 1665: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1666: exactly equal to <var title="">scriptURL</var>, then throw a
1667: <code>URL_MISMATCH_ERR</code> exception and abort all these
1668: steps.</li>
1.81 ihickson 1669:
1670: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1671:
1.185 ihickson 1672: <li><p><span>Create a new <code>MessagePort</code>
1673: object</span> owned by <var title="">worker global
1674: scope</var>. Let this be the <var title="">inside
1675: port</var>.</li>
1.81 ihickson 1676:
1677: <li><p><span>Entangle</span> <var title="">outside port</var>
1678: and <var title="">inside port</var>.</li>
1679:
1680: <li><p>Return <var title="">worker</var> and perform the next
1681: step asynchronously.</li>
1.9 ihickson 1682:
1.81 ihickson 1683: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1684: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1685: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1686: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1687: value is an array containing only the newly created port, and
1688: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1689:
1.123 ihickson 1690: <li>
1691:
1692: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1693: <var title="">worker global scope</var>'s list of <span>the
1694: worker's <code>Document</code>s</span></a> the
1695: <code>Document</code> objects in <var title="">docs</var>.</p>
1696:
1697: </li>
1698:
1.124 ihickson 1699: <li>
1700:
1.192 ihickson 1701: <p>If the <span title="script's global object">global
1702: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1703: that invoked the constructor is a
1704: <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
1705: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1706: object that is the <span title="script's global object">global
1707: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1708: that invoked the constructor.</p>
1709:
1710: </li>
1711:
1.81 ihickson 1712: <li><p>Abort all these steps.</li>
1.9 ihickson 1713:
1.155 ihickson 1714: </ol></li>
1.9 ihickson 1715:
1.185 ihickson 1716: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1717: object. Let <var title="">worker global scope</var> be this new
1718: object.</li>
1.9 ihickson 1719:
1.81 ihickson 1720: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1721:
1.115 ihickson 1722: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1723: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1724:
1.185 ihickson 1725: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.81 ihickson 1726: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1727:
1.81 ihickson 1728: <li><p><span>Entangle</span> <var title="">outside port</var> and
1729: <var title="">inside port</var>.</li>
1.9 ihickson 1730:
1.155 ihickson 1731: </ol></li>
1.28 ihickson 1732:
1.123 ihickson 1733: <li><p>Return <var title="">worker</var> and perform the remaining
1734: steps asynchronously.</li>
1.18 ihickson 1735:
1.81 ihickson 1736: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1737: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1738: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1739: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1740: is an array containing only the newly created port, and <span>queue
1741: a task</span> to dispatch the event at <var title="">worker global
1742: scope</var>.</li>
1.26 ihickson 1743:
1744: <li>
1.46 ihickson 1745:
1.123 ihickson 1746: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1747: <var title="">worker global scope</var>'s list of <span>the
1748: worker's <code>Document</code>s</span></a> the
1749: <code>Document</code> objects in <var title="">docs</var>.</p>
1750:
1751: </li>
1752:
1753: <li>
1754:
1.192 ihickson 1755: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1756: of the <span title="concept-script">script</span> that invoked the
1757: 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
1758: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1759: object that is the <span title="script's global object">global
1760: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1761: that invoked the constructor.</p>
1762:
1763: </li>
1764:
1765: <li>
1766:
1.159 ihickson 1767: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 1768: with the <span>script's browsing context</span> of the script that
1.159 ihickson 1769: invoked the method as the <var title="">owner browsing
1.176 ihickson 1770: context</var>, with the <span>origin</span> of the <span>first
1771: script</span> as the <var title="">owner origin</var>, and with
1772: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1773:
1.60 ihickson 1774: </li>
1.81 ihickson 1775:
1.155 ihickson 1776: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1777: object</span> is either a <code>Window</code> object or an object
1.155 ihickson 1778: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1779: <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 1780: interface <dfn id="workerutils">WorkerUtils</dfn> {
1781: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.115 ihickson 1782: 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 1783: };
1.184 ihickson 1784: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1785: objects, etc) are not available to workers in this version of this
1.155 ihickson 1786: 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 1787: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1788: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1789: anything. Abort these steps.</li>
1790:
1791: <li><p><span title="resolve a url">Resolve</span> each
1792: argument.</li>
1793:
1794: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1795: exception.</li>
1796:
1797: <!--
1.67 ihickson 1798: <li><p>If any of the resulting <span title="absolute URL">absolute
1799: URLs</span> have an <span>origin</span> that is not the <span
1800: title="same origin">same</span> as the origin of the script that
1.182 ihickson 1801: invoked the method, then throw a <code>SECURITY_ERR</code>
1802: exception.</p></li>
1.67 ihickson 1803: -->
1.26 ihickson 1804:
1805: <li>
1.81 ihickson 1806:
1.45 ihickson 1807: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 1808: resulting <span title="absolute URL">absolute URLs</span>, from
1.176 ihickson 1809: the <span>first script</span>'s <span>origin</span>.</p> <!-- not
1810: http-origin privacy sensitive -->
1.81 ihickson 1811:
1812: </li>
1.26 ihickson 1813:
1814: <li>
1815:
1.81 ihickson 1816: <p>For each argument in turn, in the order given, starting with
1817: the first one, run these substeps:</p>
1.26 ihickson 1818:
1.155 ihickson 1819: <ol><li>
1.26 ihickson 1820:
1.81 ihickson 1821: <p>Wait for the fetching attempt for the corresponding resource
1822: to complete.</p>
1.60 ihickson 1823:
1.81 ihickson 1824: <p>If the fetching attempt failed, throw a
1825: <code>NETWORK_ERR</code> exception and abort all these
1826: steps.</p>
1.45 ihickson 1827:
1.186 ihickson 1828: <p>If the attempt succeeds, then convert the script resource to
1829: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.85 ihickson 1830:
1831: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1832:
1.115 ihickson 1833: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1834: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1835: type.</p>
1.61 ihickson 1836:
1.81 ihickson 1837: </li>
1.26 ihickson 1838:
1.81 ihickson 1839: <li>
1.26 ihickson 1840:
1.81 ihickson 1841: <p><span>Create a script</span>, using <var title="">source</var> as the script source and <var title="">language</var> as the scripting language, using the
1.189 ihickson 1842: same global object, browsing context, URL character encoding,
1843: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 1844: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1845:
1.115 ihickson 1846: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1847: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1848: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1849: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1850:
1.199 ihickson 1851: <p>If it failed to parse, then throw an ECMAScript
1852: <code>SyntaxError</code> exception and abort all these
1853: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 1854:
1.81 ihickson 1855: <p>If an exception was raised or if the script was prematurely
1856: aborted, then abort all these steps, letting the exception or
1857: aborting continue to be processed by the script that called the
1.115 ihickson 1858: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 1859: method.</p>
1860:
1.115 ihickson 1861: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 1862: worker</a>" algorithms abort the script then abort all these
1863: steps.</p>
1864:
1865: </li>
1866:
1.155 ihickson 1867: </ol></li>
1.152 ihickson 1868:
1.155 ihickson 1869: </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 1870: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1871: the <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> interface, which
1.93 ihickson 1872: represents the identity and state of the user agent (the
1.155 ihickson 1873: client):<pre class="idl">interface <dfn id="worker-navigator" title="worker-Navigator">Navigator</dfn> {};
1.150 ihickson 1874: <a href="#worker-navigator" title="worker-Navigator">Navigator</a> implements <span>NavigatorID</span>;
1.155 ihickson 1875: <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 1876: the <code>NavigatorID</code> and <code>NavigatorOnLine</code>
1.155 ihickson 1877: interfaces. <a href="#refsHTML5">[HTML5]</a><p class="note">The <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code>
1.93 ihickson 1878: interface defined in this specification is different than the one
1.155 ihickson 1879: 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 1880: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.200 ! ihickson 1881: methods are defined in the Web SQL Database specification. <a href="#refsWEBSQL">[WEBSQL]</a><h3 id="interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</h3><p>There must be no interface objects and constructors available in
1.192 ihickson 1882: the global scope of scripts whose <span>script's global
1883: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 1884: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 1885: constructors defined by the XMLHttpRequest specifications, except
1886: that the <span>document response entity body</span> must always be
1.160 ihickson 1887: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
1888: <span>script's base URL</span>; the
1889: <span><code>XMLHttpRequest</code> origin</span> is the script's
1890: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 1891:
1892: <li><p>The <code>WebSocket</code> interface object and
1.152 ihickson 1893: constructor. <a href="#refsWEBSOCKET">[WEBSOCKET]</a></li>
1.81 ihickson 1894:
1.119 ihickson 1895: <li><p>The <code>EventSource</code> interface object and
1.152 ihickson 1896: constructor. <a href="#refsEVENTSOURCE">[EVENTSOURCE]</a></li>
1.119 ihickson 1897:
1.81 ihickson 1898: <li><p>The <code>MessageChannel</code> interface object and
1.152 ihickson 1899: constructor. <a href="#refsHTML5">[HTML5]</a></li>
1.81 ihickson 1900:
1.183 ihickson 1901: <li><p>The <code title="dom-Worker"><a href="#dom-worker">Worker</a></code> and <code title="dom-SharedWorker"><a href="#dom-sharedworker">SharedWorker</a></code> interface objects and
1902: constructors.</li>
1.81 ihickson 1903:
1.155 ihickson 1904: </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 1905: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
1906: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
1907: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
1908: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
1909: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
1910: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
1911: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
1912: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 1913: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
1914: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 1915: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 1916: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 1917: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 1918: <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>,
1919: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
1920: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
1921: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
1.163 ihickson 1922: follow the rules given for URL decomposition IDL attributes, with the
1.115 ihickson 1923: <span title="concept-uda-input">input</span> being the
1.81 ihickson 1924: <span>absolute URL</span> that the object represents (same as the
1.115 ihickson 1925: <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and
1926: the <span title="concept-uda-setter">common setter action</span>
1.178 ihickson 1927: being a no-op, since the attributes are defined to be readonly. <a href="#refsHTML5">[HTML5]</a></p><!--START vCard--><!--START vEvent--><h2 class="no-num" id="references">References</h2><!--REFS--><!--END vCard--><!--END vEvent--><p>All references are normative unless marked "Non-normative".</p><!--START vCard--><!--START vEvent--><dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.153 ihickson 1928: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
1929: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
1930: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1931: S. Byrnes. W3C, April 2004.</dd>
1932: <!--
1933: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
1934: DOM Core</a></cite>, S. Pieters. W3C, June 2009.</dd>
1935: -->
1936:
1.152 ihickson 1937: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
1938: <!--
1939: <dd><cite><a
1940: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
1941: Model (DOM) Level 3 Events Specification</a></cite>,
1942: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C, December
1943: 2007.</dd>
1944: -->
1945: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
1946: Object Model (DOM) Level 3 Events Specification</a></cite>,
1947: D. Schepers. W3C, July 2009.</dd>
1948:
1949: <dt id="refsECMA262">[ECMA262]</dt>
1950: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1951: Language Specification</a></cite>. ECMA, December 1999.</dd>
1952:
1953: <dt id="refsEVENTSOURCE">[EVENTSOURCE]</dt>
1954: <!--
1955: <dd><cite><a href="http://www.w3.org/TR/eventsource/">Server-Sent
1956: Events</a></cite>, I. Hickson. W3C, April 2009.</dd>
1957: -->
1958: <dd><cite><a href="http://dev.w3.org/html5/eventsource/">Server-Sent
1959: Events</a></cite>, I. Hickson. W3C, July 2009.</dd>
1960:
1961: <dt id="refsHTML5">[HTML5]</dt>
1962: <!--
1.161 ihickson 1963: <dd><cite><a href="http://www.w3.org/TR/html5/">HTML5</a></cite>,
1.152 ihickson 1964: I. Hickson, D. Hyatt. W3C, April 2009.</dd>
1.161 ihickson 1965: <dd><cite><a
1966: href="http://www.w3.org/html/wg/html5/">HTML5</a></cite>,
1967: I. Hickson, D. Hyatt. W3C, August 2009.</dd>
1.152 ihickson 1968: -->
1.161 ihickson 1969: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML5</a></cite>,
1970: I. Hickson. WHATWG, August 2009.</dd>
1.152 ihickson 1971:
1.154 ihickson 1972: <dt id="refsRFC2119">[RFC2119]</dt>
1973: <dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
1974: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF, March
1975: 1997.</dd>
1976:
1.200 ! ihickson 1977: <dt id="refsWEBSQL">[WEBSQL]</dt>
! 1978: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web SQL
! 1979: Database</a></cite>, I. Hickson. W3C, July 2009.</dd>
1.152 ihickson 1980:
1.154 ihickson 1981: <dt id="refsWEBIDL">[WEBIDL]</dt>
1982: <!--
1983: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
1984: IDL</a></cite>, C. McCormack. W3C, December 2008.</dd>
1985: -->
1986: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
1987: IDL</a></cite>, C. McCormack. W3C, July 2009.</dd>
1988:
1.152 ihickson 1989: <dt id="refsWEBSOCKET">[WEBSOCKET]</dt>
1990: <!--
1991: <dd><cite><a href="http://www.w3.org/TR/websockets/">The Web Sockets
1992: API</a></cite>, I. Hickson. W3C, April
1993: 2009.</dd>
1994: -->
1995: <dd><cite><a href="http://dev.w3.org/html5/websockets/">The Web Sockets
1996: API</a></cite>, I. Hickson. W3C, August
1997: 2009.</dd>
1998:
1999: <dt id="refsXHR">[XHR]</dt>
2000: <!--
2001: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
2002: Object</a></cite>, A. van Kesteren. W3C, April
2003: 2008.</dd>
2004: -->
1.160 ihickson 2005: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.152 ihickson 2006: A. van Kesteren. W3C, June 2009.</dd>
2007:
1.178 ihickson 2008: </dl><!--END vCard--><!--END vEvent--><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2009:
2010: Aaron Boodman,
1.155 ihickson 2011: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2012: Anne van Kesteren,
2013: Ben Turner,
2014: Dmitry Titov,
1.96 ihickson 2015: Drew Wilson,
1.97 ihickson 2016: Jeremy Orlow,
1.81 ihickson 2017: Jonas Sicking,
2018: Justin James,
2019: Kevin Hakanson,
2020: Maciej Stachowiak,
2021: Michael Nordman,
2022: Mike Smith,
2023:
2024: and
2025:
2026: Philip Taylor
2027:
1.155 ihickson 2028: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2029: technology and whose experience has been a huge influence on this
1.155 ihickson 2030: specification.
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