Annotation of html5/workers/Overview.html, revision 1.240
1.155 ihickson 1: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!-- when publishing, change bits marked ZZZ --><html lang="en-US-x-Hixie"><title>Web Workers</title><style type="text/css">
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1.218 ihickson 192: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><div class="head">
1.115 ihickson 193: <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 194: <h1>Web Workers</h1>
1.196 ihickson 195:
1.238 ihickson 196: <h2 class="no-num no-toc" id="editor-s-draft-25-march-2010">Editor's Draft 25 March 2010</h2>
1.218 ihickson 197: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 198: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 199: <dt>Latest Editor's Draft:</dt>
1.115 ihickson 200: <dd><a href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 201: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 202: <dt>Previous Versions:</dt>
1.113 ihickson 203: <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 204: <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 205: <!-- :ZZZ -->
1.81 ihickson 206: <dt>Editors:</dt>
1.115 ihickson 207: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 208: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
1.234 ihickson 209: © 2010 <a href="http://www.w3.org/"><abbr title="World Wide
1.155 ihickson 210: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 211: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
212: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
213: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
214: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
215: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 216: use</a> rules apply.</p>
1.201 ihickson 217:
1.155 ihickson 218: </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 219: authors to spawn background workers running scripts in parallel to
220: their main page. This allows for thread-like operation with
1.212 ihickson 221: 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 222: time of its publication. Other documents may supersede this
223: document. A list of current W3C publications and the most recently
224: formally published revision of this technical report can be found in
1.115 ihickson 225: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.201 ihickson 226: at http://www.w3.org/TR/.</em></p><!-- where to send feedback (required) --><p>If you wish to make comments regarding this document, please send
1.115 ihickson 227: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 228: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 229: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 230:
231: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 232: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
233: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 234: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 235:
1.155 ihickson 236: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 237: stable. <strong>Implementors who are not taking part in the
238: discussions are likely to find the specification changing out from
239: under them in incompatible ways.</strong> Vendors interested in
240: implementing this specification before it eventually reaches the
241: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 242: 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 243: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
244: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 245: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 246: 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 247: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 248: 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 249: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
250: <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>
251: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
252: <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 253: </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 254: Working Group</a> is the W3C working group responsible for this
255: specification's progress along the W3C Recommendation track.
1.196 ihickson 256:
1.238 ihickson 257: This specification is the 25 March 2010 Editor's Draft.
1.155 ihickson 258: </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
259: 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 260: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 261: 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 262: 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 263: any patent disclosures</a> made in connection with the deliverables
264: of the group; that page also includes instructions for disclosing a
265: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 266: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
267: Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
1.214 ihickson 268: 6 of the W3C Patent Policy</a>.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- This text will be moved back to under the copyright in the header if this is not resolved by April 2010 --><p class="alt">The <a href="http://www.whatwg.org/specs/web-workers/current-work/">WHATWG
269: version</a> of this specification is available under a license that
270: permits reuse of the specification text.</p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><h2 class="no-num no-toc" id="contents">Table of Contents</h2>
1.81 ihickson 271: <!--begin-toc-->
1.115 ihickson 272: <ol class="toc">
273: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 274: <ol>
1.115 ihickson 275: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
276: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 277: <ol>
1.115 ihickson 278: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
279: <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>
280: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.3 </span>Worker used for background I/O</a></li>
1.238 ihickson 281: <li><a href="#shared-workers-introduction"><span class="secno">1.2.4 </span>Shared workers introduction</a></li>
282: <li><a href="#shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</a></li>
283: <li><a href="#delegation"><span class="secno">1.2.6 </span>Delegation</a></li>
284: <li><a href="#providing-libraries"><span class="secno">1.2.7 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 285: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 286: <ol>
1.148 ihickson 287: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
288: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
289: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
290: <ol>
291: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 292: <ol>
1.148 ihickson 293: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
294: <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>
295: <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 296: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.186 ihickson 297: <li><a href="#the-event-loop"><span class="secno">4.3 </span>The event loop</a></li>
298: <li><a href="#the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</a></li>
299: <li><a href="#processing-model"><span class="secno">4.5 </span>Processing model</a></li>
300: <li><a href="#runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</a></li>
301: <li><a href="#creating-workers"><span class="secno">4.7 </span>Creating workers</a>
1.81 ihickson 302: <ol>
1.186 ihickson 303: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
304: <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>
305: <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 306: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 307: <ol>
1.148 ihickson 308: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
1.210 ihickson 309: <li><a href="#the-workernavigator-object"><span class="secno">5.2 </span>The <code>WorkerNavigator</code> object</a></li>
1.148 ihickson 310: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
311: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
312: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 313: <li><a class="no-num" href="#references">References</a></li>
314: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 315: <!--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
316: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 317: scripts that respond to clicks or other user interactions, and
318: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 319: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 320: relatively heavy-weight, and are not intended to be used in large
321: numbers. For example, it would be inappropriate to launch one worker
322: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 323: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
324: 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
325: 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
326: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
327: (naïvely) compute prime numbers, and progressively displays the
328: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 329: <html>
330: <head>
331: <title>Worker example: One-core computation</title>
332: </head>
333: <body>
334: <p>The highest prime number discovered so far is: <output id="result"></output></p>
335: <script>
1.50 ihickson 336: var worker = new Worker('worker.js');
337: worker.onmessage = function (event) {
1.54 ihickson 338: document.getElementById('result').textContent = event.data;
1.29 ihickson 339: };
1.81 ihickson 340: </script>
341: </body>
1.155 ihickson 342: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 343: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 344: representing that worker, which is used to communicate with the
1.177 ihickson 345: 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 346: search: while (true) {
347: n += 1;
348: for (var i = 2; i <= Math.sqrt(n); i += 1)
349: if (n % i == 0)
350: continue search;
351: // found a prime!
1.50 ihickson 352: postMessage(n);
1.155 ihickson 353: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 354: 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 355: 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 356: task is to listen for notifications from the server, and, when
357: appropriate, either add or remove data from the client-side
1.155 ihickson 358: database.<p>Since no communication occurs between the worker and the main
359: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 360: new Worker('worker.js');
1.155 ihickson 361: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 362: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 363: server.onmessage = function (event) {
364: // data is in the format "command key value"
1.54 ihickson 365: var data = event.data.split(' ');
1.31 ihickson 366: switch (data[0]) {
367: case '+':
368: database.transaction(function(tx) {
369: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
370: });
371: case '-':
372: database.transaction(function(tx) {
373: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
374: });
375: }
1.155 ihickson 376: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 377: mechanism and opens the local database (which, we presume, has been
378: created earlier). The worker then just listens for messages from the
379: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 380: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 381: this example online</a>. (This example will not actually function,
382: since the server does not actually exist and the database is not
1.155 ihickson 383: 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 384: fetching stock updates for at regular intervals, and one for
1.155 ihickson 385: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 386: <html>
387: <head>
388: <title>Worker example: Stock ticker</title>
389: <script>
1.33 ihickson 390: // TICKER
391: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 392: var ticker = new Worker('ticker.js');
1.33 ihickson 393:
394: // SEARCHER
1.50 ihickson 395: var searcher = new Worker('searcher.js');
1.33 ihickson 396: function search(query) {
1.50 ihickson 397: searcher.postMessage(query);
1.33 ihickson 398: }
399:
400: // SYMBOL SELECTION UI
401: function select(newSymbol) {
402: symbol = newSymbol;
1.50 ihickson 403: ticker.postMessage(symbol);
1.33 ihickson 404: }
1.81 ihickson 405: </script>
406: </head>
1.122 ihickson 407: <body onload="search('')">
1.81 ihickson 408: <p><output id="symbol"></output> <output id="value"></output></p>
409: <script>
1.50 ihickson 410: ticker.onmessage = function (event) {
1.54 ihickson 411: var data = event.data.split(' ');
1.33 ihickson 412: document.getElementById('symbol').textContent = data[0];
413: document.getElementById('value').textContent = data[1];
414: };
1.50 ihickson 415: ticker.postMessage(symbol);
1.81 ihickson 416: </script>
1.122 ihickson 417: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 418: <ul id="results"></ul>
419: <script>
1.50 ihickson 420: searcher.onmessage = function (event) {
1.54 ihickson 421: var data = event.data.split(' ');
1.33 ihickson 422: var results = document.getElementById('results');
423: while (results.hasChildNodes()) // clear previous results
424: results.removeChild(results.firstChild);
425: for (var i = 0; i < data.length; i += 1) {
426: // add a list item with a button for each result
427: var li = document.createElement('li');
428: var button = document.createElement('button');
429: button.value = data[i];
430: button.type = 'button';
431: button.onclick = function () { select(this.value); };
432: button.textContent = data[i];
433: li.appendChild(button);
434: results.appendChild(li);
435: }
436: };
1.81 ihickson 437: </script>
438: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
439: </body>
1.155 ihickson 440: </html></pre><p>The two workers use a common library for performing the actual
441: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 442: try {
443: var xhr = new XMLHttpRequest();
444: xhr.open('GET', url, false);
445: xhr.send();
446: return xhr.responseText;
447: } catch (e) {
448: return ''; // turn all errors into empty results
449: }
1.155 ihickson 450: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 451: var timer;
452: var symbol;
453: function update() {
1.50 ihickson 454: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 455: timer = setTimeout(update, 10000);
456: }
1.50 ihickson 457: onmessage = function (event) {
1.33 ihickson 458: if (timer)
459: clearTimeout(timer);
1.54 ihickson 460: symbol = event.data;
1.33 ihickson 461: update();
1.155 ihickson 462: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 463: onmessage = function (event) {
1.54 ihickson 464: postMessage(get('search.cgi?' + event.data));
1.238 ihickson 465: };</pre><p><a href="http://www.whatwg.org/demos/workers/stocks/page.html">View this example online</a>.<h4 id="shared-workers-introduction"><span class="secno">1.2.4 </span>Shared workers introduction</h4><p><i>This section is non-normative.</i><p>This section introduces shared workers using a Hello World
466: example. Shared workers use slightly different APIs, since each
467: worker can have multiple connections.<p>This first example shows how you connect to a worker and how a
468: worker can send a message back to the page when it connects to
1.239 ihickson 469: it. Received messages are displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
470: <title>Shared workers: demo 1</title>
471: <pre id="log">Log:</pre>
472: <script>
473: var worker = new SharedWorker('test.js');
474: var log = document.getElementById('log');
475: worker.port.onmessage = function(e) { // note: not worker.onmessage!
476: log.textContent += '\n' + e.data;
477: }
478: </script>
479: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
480: var port = e.ports[0];
481: port.postMessage('Hello World!');
482: }
483: </pre><hr><p>This second example extends the first one by changing two things:
1.238 ihickson 484: first, messages are received using <code title="">addEventListener()</code> instead of an <span title="event
485: handler IDL attributes">event handler IDL attribute</span>, and
486: second, a message is sent <em>to</em> the worker, causing the worker
487: to send another message in return. Received messages are again
1.239 ihickson 488: displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
1.240 ! ihickson 489: <title>Shared workers: demo 2</title>
1.239 ihickson 490: <pre id="log">Log:</pre>
491: <script>
492: var worker = new SharedWorker('test.js');
493: var log = document.getElementById('log');
1.240 ! ihickson 494: worker.port.addEventListener('message', function(e) {
1.239 ihickson 495: log.textContent += '\n' + e.data;
1.240 ! ihickson 496: }, false);
! 497: worker.port.start(); // note: need this when using addEventListener
! 498: worker.port.postMessage('ping');
1.239 ihickson 499: </script>
500: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
501: var port = e.ports[0];
502: port.postMessage('Hello World!');
1.240 ! ihickson 503: port.onmessage = function(e) {
! 504: port.postMessage('pong'); // not e.ports[0].postMessage!
! 505: // e.target.postMessage('pong'); would work also
! 506: }
1.239 ihickson 507: }
508: </pre><hr><p>Finally, the example is extended to show how two pages can
1.238 ihickson 509: connect to the same worker; in this case, the second page is merely
510: in an <code>iframe</code> on the first page, but the same principle
511: would apply to an entirely separate page in a separate
1.239 ihickson 512: <span>top-level browsing context</span>.<p>Here is the outer HTML page:<pre><!DOCTYPE HTML>
513: <title>Shared workers: demo 3</title>
514: <pre id="log">Log:</pre>
515: <script>
516: var worker = new SharedWorker('test.js');
517: var log = document.getElementById('log');
518: worker.port.addEventListener('message', function(e) {
519: log.textContent += '\n' + e.data;
520: }, false);
521: worker.port.start();
522: worker.port.postMessage('ping');
523: </script>
524: <iframe src="inner.html"></iframe>
525: </pre><p>Here is the inner HTML page:<pre><!DOCTYPE HTML>
526: <title>Shared workers: demo 3 inner frame</title>
527: <pre id=log>Inner log:</pre>
528: <script>
529: var worker = new SharedWorker('test.js');
530: var log = document.getElementById('log');
531: worker.port.onmessage = function(e) {
532: log.textContent += '\n' + e.data;
533: }
534: </script>
535: </pre><p>Here is the JavaScript worker:<pre>var count = 0;
536: onconnect = function(e) {
537: count += 1;
538: var port = e.ports[0];
539: port.postMessage('Hello World! You are connection #' + count);
540: port.onmessage = function(e) {
541: port.postMessage('pong');
542: }
543: }
544: </pre><h4 id="shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</h4><p><i>This section is non-normative.</i><p>In this example, multiple windows (viewers) can be opened that
1.81 ihickson 545: are all viewing the same map. All the windows share the same map
546: information, with a single worker coordinating all the viewers. Each
547: viewer can move around independently, but if they set any data on
1.155 ihickson 548: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
549: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 550: <html>
551: <head>
552: <title>Workers example: Multiviewer</title>
553: <script>
1.36 ihickson 554: function openViewer() {
555: window.open('viewer.html');
556: }
1.81 ihickson 557: </script>
558: </head>
559: <body>
560: <p><button type=button onclick="openViewer()">Open a new
561: viewer</button></p>
562: <p>Each viewer opens in a new window. You can have as many viewers
563: as you like, they all view the same data.</p>
564: </body>
1.155 ihickson 565: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 566: <html>
567: <head>
568: <title>Workers example: Multiviewer viewer</title>
569: <script>
1.50 ihickson 570: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 571:
572: // CONFIGURATION
573: function configure(event) {
1.54 ihickson 574: if (event.data.substr(0, 4) != 'cfg ') return;
575: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 576: // update display to mention our name is name
577: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
578: // no longer need this listener
1.43 ihickson 579: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 580: }
1.53 ihickson 581: worker.port.addEventListener('message', configure, false);
1.36 ihickson 582:
583: // MAP
584: function paintMap(event) {
1.54 ihickson 585: if (event.data.substr(0, 4) != 'map ') return;
586: var data = event.data.substr(4).split(',');
1.36 ihickson 587: // display tiles data[0] .. data[8]
588: var canvas = document.getElementById('map');
589: var context = canvas.getContext('2d');
590: for (var y = 0; y < 3; y += 1) {
591: for (var x = 0; x < 3; x += 1) {
592: var tile = data[y * 3 + x];
593: if (tile == '0')
594: context.fillStyle = 'green';
595: else
596: context.fillStyle = 'maroon';
597: fillRect(x * 50, y * 50, 50, 50);
598: }
599: }
600: }
1.53 ihickson 601: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 602:
603: // PUBLIC CHAT
604: function updatePublicChat(event) {
1.54 ihickson 605: if (event.data.substr(0, 4) != 'txt ') return;
606: var name = event.data.substr(4).split(' ', 1);
607: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 608: // display "<name> message" in public chat
1.36 ihickson 609: var dialog = document.getElementById('public');
610: var dt = document.createElement('dt');
611: dt.textContent = name;
612: dialog.appendChild(dt);
613: var dd = document.createElement('dd');
614: dd.textContent = message;
615: dialog.appendChild(dd);
616: }
1.53 ihickson 617: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 618:
619: // PRIVATE CHAT
620: function startPrivateChat(event) {
1.54 ihickson 621: if (event.data.substr(0, 4) != 'msg ') return;
622: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 623: var port = event.ports[0];
1.36 ihickson 624: // display a private chat UI
625: var ul = document.getElementById('private');
626: var li = document.createElement('li');
627: var h3 = document.createElement('h3');
628: h3.textContent = 'Private chat with ' + name;
629: li.appendChild(h3);
630: var dialog = document.createElement('dialog');
631: var addMessage = function(name, message) {
632: var dt = document.createElement('dt');
633: dt.textContent = name;
634: dialog.appendChild(dt);
635: var dd = document.createElement('dd');
636: dd.textContent = message;
637: dialog.appendChild(dd);
638: };
639: port.onmessage = function (event) {
1.54 ihickson 640: addMessage(name, event.data);
1.36 ihickson 641: };
642: li.appendChild(dialog);
643: var form = document.createElement('form');
644: var p = document.createElement('p');
645: var input = document.createElement('input');
646: input.size = 50;
647: p.appendChild(input);
648: p.appendChild(document.createTextNode(' '));
649: var button = document.createElement('button');
650: button.textContent = 'Post';
651: p.appendChild(button);
652: form.onsubmit = function () {
653: port.postMessage(input.value);
654: addMessage('me', input.value);
655: input.value = '';
656: return false;
657: };
658: form.appendChild(p);
659: li.appendChild(form);
660: }
1.53 ihickson 661: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 662:
663: worker.port.start();
1.81 ihickson 664: </script>
665: </head>
666: <body>
667: <h1>Viewer</h1>
668: <h2>Map</h2>
669: <p><canvas id="map" height=150 width=150></canvas></p>
670: <p>
671: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
672: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
673: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
674: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
675: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
676: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
677: </p>
678: <h2>Public Chat</h2>
679: <dialog id="public"></dialog>
680: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
681: <p>
682: <input type="text" name="message" size="50">
683: <button>Post</button>
684: </p>
685: </form>
686: <h2>Private Chat</h2>
687: <ul id="private"></ul>
688: </body>
689: </html>
1.155 ihickson 690: </pre><p>There are several key things worth noting about the way the
691: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 692: processing function, the code here attaches multiple event
693: listeners, each one performing a quick check to see if it is
694: relevant for the message. In this example it doesn't make much
695: difference, but if multiple authors wanted to collaborate using a
696: single port to communicate with a worker, it would allow for
697: independent code instead of changes having to all be made to a
1.155 ihickson 698: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 699: unregister specific listeners when you are done with them, as is
700: done with the <code title="">configure()</code> method in this
1.155 ihickson 701: example.<p>Finally, the worker:<pre>
702: var nextName = 0;
1.36 ihickson 703: function getNextName() {
704: // this could use more friendly names
705: // but for now just return a number
706: return nextName++;
707: }
708:
709: var map = [
710: [0, 0, 0, 0, 0, 0, 0],
711: [1, 1, 0, 1, 0, 1, 1],
712: [0, 1, 0, 1, 0, 0, 0],
713: [0, 1, 0, 1, 0, 1, 1],
714: [0, 0, 0, 1, 0, 0, 0],
715: [1, 0, 0, 1, 1, 1, 1],
716: [1, 1, 0, 1, 1, 0, 1],
717: ];
718:
719: function wrapX(x) {
720: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 721: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 722: return x;
723: }
724:
725: function wrapY(y) {
726: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 727: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 728: return y;
729: }
730:
1.50 ihickson 731: function sendMapData(callback) {
1.36 ihickson 732: var data = '';
733: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
734: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
735: if (data != '')
736: data += ',';
737: data += map[y][x];
738: }
739: }
1.50 ihickson 740: callback('map ' + data);
1.36 ihickson 741: }
742:
743: var viewers = {};
744: onconnect = function (event) {
1.84 ihickson 745: event.ports[0]._name = getNextName();
746: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
747: viewers[event.ports[0]._name] = event.port._data;
748: event.ports[0].postMessage('cfg ' + name);
749: event.ports[0].onmessage = getMessage;
750: sendMapData(event.ports[0].postMessage);
1.36 ihickson 751: };
752:
753: function getMessage(event) {
1.54 ihickson 754: switch (event.data.substr(0, 4)) {
1.36 ihickson 755: case 'mov ':
1.54 ihickson 756: var direction = event.data.substr(4);
1.36 ihickson 757: var dx = 0;
758: var dy = 0;
759: switch (direction) {
760: case 'up': dy = -1; break;
761: case 'down': dy = 1; break;
762: case 'left': dx = -1; break;
763: case 'right': dx = 1; break;
764: }
765: event.target._data.x = wrapX(event.target._data.x + dx);
766: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 767: sendMapData(event.target.postMessage);
1.36 ihickson 768: break;
769: case 'set ':
1.54 ihickson 770: var value = event.data.substr(4);
1.36 ihickson 771: map[event.target._data.y][event.target._data.x] = value;
772: for (var viewer in viewers)
1.50 ihickson 773: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 774: break;
775: case 'txt ':
776: var name = event.target._name;
1.54 ihickson 777: var message = event.data.substr(4);
1.36 ihickson 778: for (var viewer in viewers)
779: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
780: break;
781: case 'msg ':
782: var party1 = event._data;
1.54 ihickson 783: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 784: if (party2) {
785: var channel = new MessageChannel();
1.84 ihickson 786: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
787: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 788: }
789: break;
790: }
1.155 ihickson 791: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 792: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 793: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 794: "msg" message from one viewer naming another viewer, it sets up a
795: direct connection between the two, so that the two viewers can
796: communicate directly without the worker having to proxy all the
1.238 ihickson 797: messages.<p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View this example online</a>.<h4 id="delegation"><span class="secno">1.2.6 </span>Delegation</h4><p><i>This section is non-normative.</i><p>With multicore CPUs becoming prevalent, one way to obtain better
1.81 ihickson 798: performance is to split computationally expensive tasks amongst
799: multiple workers. In this example, a computationally expensive task
800: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 801: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 802: <html>
803: <head>
1.203 ihickson 804: <title>Worker example: Multicore computation</title>
1.81 ihickson 805: </head>
806: <body>
1.203 ihickson 807: <p>Result: <output id="result"></output></p>
1.81 ihickson 808: <script>
1.50 ihickson 809: var worker = new Worker('worker.js');
810: worker.onmessage = function (event) {
1.54 ihickson 811: document.getElementById('result').textContent = event.data;
1.40 ihickson 812: };
1.81 ihickson 813: </script>
814: </body>
1.155 ihickson 815: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 816: var num_workers = 10;
817: var items_per_worker = 1000000;
818:
819: // start the workers
820: var result = 0;
821: var pending_workers = num_workers;
822: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 823: var worker = new Worker('core.js');
824: worker.postMessage(i * items_per_worker);
825: worker.postMessage((i+1) * items_per_worker);
826: worker.onmessage = storeResult;
1.40 ihickson 827: }
828:
829: // handle the results
830: function storeResult(event) {
1.54 ihickson 831: result += 1*event.data;
1.40 ihickson 832: pending_workers -= 1;
833: if (pending_workers <= 0)
1.50 ihickson 834: postMessage(result); // finished!
1.155 ihickson 835: }</pre><p>It consists of a loop to start the subworkers, and then a handler
836: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 837: onmessage = getStart;
1.40 ihickson 838: function getStart(event) {
1.54 ihickson 839: start = 1*event.data;
1.40 ihickson 840: onmessage = getEnd;
841: }
842:
843: var end;
844: function getEnd(event) {
1.54 ihickson 845: end = 1*event.data;
1.40 ihickson 846: onmessage = null;
1.66 ihickson 847: work();
1.40 ihickson 848: }
849:
1.66 ihickson 850: function work() {
1.40 ihickson 851: var result = 0;
852: for (var i = start; i < end; i += 1) {
853: // perform some complex calculation here
854: result += 1;
855: }
1.50 ihickson 856: postMessage(result);
857: close();
1.155 ihickson 858: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 859: for the range of numbers thus specified, and then report the result
1.238 ihickson 860: back to the parent.<p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.<h4 id="providing-libraries"><span class="secno">1.2.7 </span>Providing libraries</h4><p><i>This section is non-normative.</i><p>Suppose that a cryptography library is made available that
1.155 ihickson 861: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 862:
863: <dd>Takes a port, on which it will send two messages, first the
864: public key and then the private key.</dd>
865:
866: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
867:
868: <dd>Takes a port, to which any number of messages can be sent, the
869: first giving the public key, and the remainder giving the
870: plaintext, each of which is encrypted and then sent on that same
871: channel as the cyphertext. The user can close the port when it is
872: done encrypting content.</dd>
873:
874: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
875:
876: <dd>Takes a port, to which any number of messages can be sent, the
877: first giving the private key, and the remainder giving the
878: cyphertext, each of which is decrypted and then sent on that same
879: channel as the plaintext. The user can close the port when it is
880: done decrypting content.</dd>
1.49 ihickson 881:
1.155 ihickson 882: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 883: if (e.data == "genkeys")
1.84 ihickson 884: genkeys(e.ports[0]);
1.54 ihickson 885: else if (e.data == "encrypt")
1.84 ihickson 886: encrypt(e.ports[0]);
1.54 ihickson 887: else if (e.data == "decrypt")
1.84 ihickson 888: decrypt(e.ports[0]);
1.49 ihickson 889: }
890:
891: function genkeys(p) {
892: var keys = _generateKeyPair();
893: p.postMessage(keys[0]);
894: p.postMessage(keys[1]);
895: }
896:
897: function encrypt(p) {
898: var key, state = 0;
899: p.onmessage = function (e) {
900: if (state == 0) {
1.54 ihickson 901: key = e.data;
1.49 ihickson 902: state = 1;
903: } else {
1.54 ihickson 904: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 905: }
906: };
907: }
908:
909: function decrypt(p) {
910: var key, state = 0;
911: p.onmessage = function (e) {
912: if (state == 0) {
1.54 ihickson 913: key = e.data;
1.49 ihickson 914: state = 1;
915: } else {
1.54 ihickson 916: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 917: }
918: };
919: }
920:
1.50 ihickson 921: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 922: if ('onmessage' in this) // dedicated worker
1.50 ihickson 923: onmessage = handleMessage;
924: else // shared worker
925: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 926:
927:
928: // the "crypto" functions:
929:
930: function _generateKeyPair() {
931: return [Math.random(), Math.random()];
932: }
933:
934: function _encrypt(k, s) {
935: return 'encrypted-' + k + ' ' + s;
936: }
937:
938: function _decrypt(k, s) {
939: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 940: }</pre><p>Note that the crypto functions here are just stubs and don't do
941: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 942: <html>
943: <head>
944: <title>Worker example: Crypto library</title>
945: <script>
1.50 ihickson 946: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 947: function getKeys() {
948: var state = 0;
1.50 ihickson 949: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 950: if (state == 0)
1.54 ihickson 951: document.getElementById('public').value = e.data;
1.49 ihickson 952: else if (state == 1)
1.54 ihickson 953: document.getElementById('private').value = e.data;
1.49 ihickson 954: state += 1;
955: };
956: }
957: function enc() {
1.50 ihickson 958: var port = cryptoLib.startConversation("encrypt");
959: port.postMessage(document.getElementById('public').value);
960: port.postMessage(document.getElementById('input').value);
961: port.onmessage = function (e) {
1.54 ihickson 962: document.getElementById('input').value = e.data;
1.50 ihickson 963: port.close();
1.49 ihickson 964: };
965: }
966: function dec() {
1.50 ihickson 967: var port = cryptoLib.startConversation("decrypt");
968: port.postMessage(document.getElementById('private').value);
969: port.postMessage(document.getElementById('input').value);
970: port.onmessage = function (e) {
1.54 ihickson 971: document.getElementById('input').value = e.data;
1.50 ihickson 972: port.close();
1.49 ihickson 973: };
974: }
1.81 ihickson 975: </script>
976: <style>
1.49 ihickson 977: textarea { display: block; }
1.81 ihickson 978: </style>
979: </head>
980: <body onload="getKeys()">
981: <fieldset>
982: <legend>Keys</legend>
983: <p><label>Public Key: <textarea id="public"></textarea></label></p>
984: <p><label>Private Key: <textarea id="private"></textarea></label></p>
985: </fieldset>
986: <p><label>Input: <textarea id="input"></textarea></label></p>
987: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
988: </body>
1.155 ihickson 989: </html></pre><p>A later version of the API, though, might want to offload all the
990: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 991: if (e.data == "genkeys")
1.84 ihickson 992: genkeys(e.ports[0]);
1.54 ihickson 993: else if (e.data == "encrypt")
1.84 ihickson 994: encrypt(e.ports[0]);
1.54 ihickson 995: else if (e.data == "decrypt")
1.84 ihickson 996: decrypt(e.ports[0]);
1.49 ihickson 997: }
998:
999: function genkeys(p) {
1.50 ihickson 1000: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 1001: generator.postMessage('', [p]);
1.49 ihickson 1002: }
1003:
1004: function encrypt(p) {
1005: p.onmessage = function (e) {
1.54 ihickson 1006: var key = e.data;
1.50 ihickson 1007: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 1008: encryptor.postMessage(key, [p]);
1.49 ihickson 1009: };
1010: }
1011:
1012: function encrypt(p) {
1013: p.onmessage = function (e) {
1.54 ihickson 1014: var key = e.data;
1.50 ihickson 1015: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 1016: decryptor.postMessage(key, [p]);
1.49 ihickson 1017: };
1018: }
1019:
1.50 ihickson 1020: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 1021: if ('onmessage' in this) // dedicated worker
1.50 ihickson 1022: onmessage = handleMessage;
1023: else // shared worker
1.84 ihickson 1024: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 1025: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 1026: var k = _generateKeyPair();
1.84 ihickson 1027: e.ports[0].postMessage(k[0]);
1028: e.ports[0].postMessage(k[1]);
1.49 ihickson 1029: close();
1030: }
1.50 ihickson 1031:
1032: function _generateKeyPair() {
1033: return [Math.random(), Math.random()];
1.155 ihickson 1034: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 1035: var key = e.data;
1.84 ihickson 1036: e.ports[0].onmessage = function (e) {
1.54 ihickson 1037: var s = e.data;
1.50 ihickson 1038: postMessage(_encrypt(key, s));
1.49 ihickson 1039: }
1.50 ihickson 1040: }
1041:
1042: function _encrypt(k, s) {
1043: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 1044: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 1045: var key = e.data;
1.84 ihickson 1046: e.ports[0].onmessage = function (e) {
1.54 ihickson 1047: var s = e.data;
1.50 ihickson 1048: postMessage(_decrypt(key, s));
1.49 ihickson 1049: }
1.50 ihickson 1050: }
1051:
1052: function _decrypt(k, s) {
1053: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 1054: }</pre><p>Notice how the users of the API don't have to even know that this
1055: is happening — the API hasn't changed; the library can
1.81 ihickson 1056: delegate to subworkers without changing its API, even though it is
1.155 ihickson 1057: 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 1058: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 1059: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 1060: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
1061: "OPTIONAL" in the normative parts of this document are to be
1062: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 1063: 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 1064: (such as "strip any leading space characters" or "return false and
1065: abort these steps") are to be interpreted with the meaning of the
1066: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 1067: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 1068: attributes, methods or objects. Such requirements are to be
1.155 ihickson 1069: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 1070: may be implemented in any manner, so long as the end result is
1071: equivalent. (In particular, the algorithms defined in this
1072: specification are intended to be easy to follow, and not intended to
1.155 ihickson 1073: be performant.)<p>The only conformance class defined by this specification is user
1074: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 1075: otherwise unconstrained inputs, e.g. to prevent denial of service
1076: attacks, to guard against running out of memory, or to work around
1.229 ihickson 1077: platform-specific limitations.<p>When support for a feature is disabled (e.g. as an emergency
1078: measure to mitigate a security problem, or to aid in development, or
1079: for performance reasons), user agents must act as if they had no
1080: support for the feature whatsoever, and as if the feature was not
1081: mentioned in this specification. For example, if a particular
1082: feature is accessed via an attribute in a Web IDL interface, the
1083: attribute itself would be omitted from the objects that implement
1084: that interface — leaving the attribute on the object but
1085: making it return null or throw an exception is insufficient.<h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3><p>This specification relies on several other underlying
1.226 ihickson 1086: specifications.<dl><dt>HTML</dt>
1.49 ihickson 1087:
1.81 ihickson 1088: <dd>
1.49 ihickson 1089:
1.226 ihickson 1090: <p>Many fundamental concepts from HTML are used by this
1091: specification. <a href="#refsHTML">[HTML]</a></p>
1.49 ihickson 1092:
1.81 ihickson 1093: </dd>
1.1 ihickson 1094:
1.81 ihickson 1095: <dt>WebIDL</dt>
1.1 ihickson 1096:
1097: <dd>
1098:
1.81 ihickson 1099: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 1100: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 1101:
1.81 ihickson 1102: </dd>
1.1 ihickson 1103:
1.155 ihickson 1104: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 1105: <code title="">Foo</code> is actually an interface, is sometimes
1106: used instead of the more accurate "an object implementing the
1.155 ihickson 1107: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1108: scripts in Web applications, and does not necessarily imply the
1109: existence of an actual <code>Document</code> object or of any other
1110: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 1111: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1112: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1113: <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 1114: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1115: 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 1116: workers. Dedicated workers, once created, and are linked to their
1117: creator; but message ports can be used to communicate from a
1118: dedicated worker to multiple other browsing contexts or
1119: workers. Shared workers, on the other hand, are named, and once
1120: created any script running in the same <span>origin</span> can
1.155 ihickson 1121: 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 1122: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1123: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1124:
1125: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1126: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1127: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1128: };
1.172 ihickson 1129: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
1130: <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 1131: 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 1132: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1133: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1134: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1135: 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 1136: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1137: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1138: have been added to the <span>event loop</span>'s <span title="task
1139: queue">task queues</span>.</p>
1140:
1141: <!-- v2-onclose
1142: <li><p><span>Queue a task</span> to <span>fire a simple
1.179 ihickson 1143: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1144: <code>WorkerGlobalScope</code> object.</p></li>
1145: -->
1.81 ihickson 1146:
1.115 ihickson 1147: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1148: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1149: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1150:
1.124 ihickson 1151: <li><p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1.123 ihickson 1152: ports</a>.</li>
1.81 ihickson 1153:
1.177 ihickson 1154: </ol><p>The following are the <span>event handlers</span> (and their
1155: corresponding <span title="event handler event type">event handler
1156: event types</span>) that must be supported, as IDL attributes, by
1157: objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1158: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1159: <tbody><!-- v2-onclose <tr><td><dfn title="handler-WorkerGlobalScope-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> --><tr><td><dfn id="handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.209 ihickson 1160: </table><hr><p>The <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface must not exist if
1161: the interface's <span>relevant namespace object</span> is a
1162: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h4 id="dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.1.2 </span>Dedicated workers and the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> interface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1163: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.174 ihickson 1164: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.77 ihickson 1165: <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1166: attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1167: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1168: had an implicit <code>MessagePort</code> associated with them. This
1169: port is part of a channel that is set up when the worker is created,
1170: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1171: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1172: 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 1173: and <dfn
1174: title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
1.81 ihickson 1175: method<!--s (startConversation)--> on
1.115 ihickson 1176: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.81 ihickson 1177: invoked, it<!--/they (startConversation)--> immediately invoked the
1178: method of the same name on the port, with the same arguments, and
1.177 ihickson 1179: returned the same return value.<p>The following are the <span>event handlers</span> (and their
1180: corresponding <span title="event handler event type">event handler
1181: event types</span>) that must be supported, as IDL attributes, by
1182: objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1183: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1184: <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 1185: </table><p>For the purposes of the <span>application cache</span> networking
1186: model, a dedicated worker is an extension of the <span>cache
1187: 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 1188: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1189: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1190: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.144 ihickson 1191: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1192: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1193: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1194: attribute must return the value it was assigned when the
1.115 ihickson 1195: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1196: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1197: that can be used to obtain a reference to the worker using the
1.177 ihickson 1198: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handlers</span> (and their
1199: corresponding <span title="event handler event type">event handler
1200: event types</span>) that must be supported, as IDL attributes, by
1201: objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1202: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1203: <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 1204: </table><p>For the purposes of the <span>application cache</span> networking
1205: model, a shared worker is its own <span>cache host</span>. The
1206: <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1207: worker with an <span>application cache</span>.<p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
1.123 ihickson 1208: attribute returns the <code>ApplicationCache</code> object for the
1.101 ihickson 1209: worker.</p><!-- normative conf criteria is in the appcache section
1.160 ihickson 1210: --><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 1211: origin</span> of scripts running in workers are the
1212: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1213: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.186 ihickson 1214: 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 1215: loop</span> distinct from those defined for <span title="unit of
1216: related similar-origin browsing contexts">units of related
1217: similar-origin browsing contexts</span>. This <span>event
1218: loop</span> has no associated <span>browsing context</span>, and its
1219: <span title="task queue">task queues</span> only have events,
1220: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1221: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1222: <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 1223: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1224: 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 1225: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1226: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1227: already on the queue are unaffected except where otherwise
1.115 ihickson 1228: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1229: timers stop firing, notifications for all pending asynchronous
1.186 ihickson 1230: 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 1231: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1232: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1233: consists of all the <code>MessagePort</code> objects that are
1234: entangled with another port and that have one (but only one) port
1235: owned by <var title="">worker global scope</var>. This list includes
1236: <!--all the <code>MessagePort</code> objects that are in events
1.68 ihickson 1237: pending in the <span>event loop</span>, as well as (commented out
1238: because in practice it makes no difference either way as far as I
1239: can tell, and it would be hard to strictly implement since these
1.81 ihickson 1240: ports might not yet be across the thread boundary)--> the implicit
1.155 ihickson 1241: <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 1242: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1243: 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 1244: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1245: 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 1246: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1247: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1248: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1249: <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 1250: documents">add <var title="">d</var> to <var title="">q</var>'s
1251: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.155 ihickson 1252: <code>Document</code>s</span></a>.</p><!-- suggestions welcome
1253: on making this sentence into understandable English --><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1254: Document">discarded</span>, it must be removed from the list of
1255: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.192 ihickson 1256: whose list contains that <code>Document</code>.<p>Given a <span>script's global object</span> <var title="">o</var>
1.123 ihickson 1257: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1258: <code>Document</code> objects to add</dfn> depends on the type of
1259: <var title="">o</var>. If <var title="">o</var> is a
1260: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1261: nested worker), then the relevant <code>Document</code>s are the
1262: <code>Document</code>s that are in <var title="">o</var>'s own list
1263: 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
1264: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1265: <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 1266: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1267: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1268: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1269: timers, database transactions, or network connections, or its list
1.124 ihickson 1270: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1271: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1272: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1273: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1274: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1275: <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 1276: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.186 ihickson 1277: <a href="#permissible-worker">permissible worker</a>.<h3 id="processing-model"><span class="secno">4.5 </span>Processing model</h3><p>When a user agent is to <dfn id="run-a-worker">run a worker</dfn> for a script with
1.232 ihickson 1278: <span>URL</span> <var title="">url</var>, a <span>browsing
1279: context</span> <var title="">owner browsing context</var>, a
1280: <code>Document</code> <var title="">owner document</var>, an
1281: <span>origin</span> <var title="">owner origin</var>, and with
1282: global scope <var title="">worker global scope</var>, it must run
1283: the following steps:<ol><li>
1.81 ihickson 1284:
1285: <p>Create a completely separate and parallel execution environment
1286: (i.e. a separate thread or process or equivalent construct), and
1.106 ihickson 1287: run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1288:
1289: </li>
1.4 ihickson 1290:
1.101 ihickson 1291: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1292: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1293: shared worker), and there are any <span title="relevant application
1294: cache">relevant application caches</span> that are identified by a
1295: 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 1296: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1297: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1298: cache</span> of those that match.</li>
1299:
1.4 ihickson 1300: <li>
1.52 ihickson 1301:
1.176 ihickson 1302: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>.</p>
1303: <!-- not http-origin privacy sensitive -->
1.81 ihickson 1304:
1.129 ihickson 1305: <p>If the attempt fails, or if the attempt involves any redirects
1306: 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
1307: origin</span> as the original <var title="">url</var>), then for
1308: each <code><a href="#worker">Worker</a></code> or <code><a href="#sharedworker">SharedWorker</a></code> object
1309: associated with <var title="">worker global scope</var>,
1310: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1311: named <code title="event-error">error</code> at that
1.129 ihickson 1312: object. Abort these steps.</p>
1.7 ihickson 1313:
1.186 ihickson 1314: <p>If the attempt succeeds, then convert the script resource to
1315: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.81 ihickson 1316:
1.68 ihickson 1317: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1318:
1.115 ihickson 1319: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1320: type of the script is ignored. Unlike with <code>script</code>
1321: elements, there is no way to override the type. It's always
1.170 ihickson 1322: assumed to be JavaScript.</p>
1.81 ihickson 1323:
1324: </li>
1.7 ihickson 1325:
1326: <li>
1.68 ihickson 1327:
1.115 ihickson 1328: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1329: created, as follows.</p>
1330:
1331: <p>Create a new <span>script execution environment</span>
1332: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1333:
1.68 ihickson 1334: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1335: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1336: entry-points</span>; set the <i>initial code entry-point</i> to
1337: the entry-point for any executable code to be immediately run.</p>
1338:
1339: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1340:
1341: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1342:
1.232 ihickson 1343: <p>Set the <span>script's document</span> to <var title="">owner
1344: document</var>.</p>
1345:
1.83 ihickson 1346: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1347: UTF-8. (This is just used for encoding non-ASCII characters in the
1348: query component of URLs.)</p>
1.68 ihickson 1349:
1350: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1351:
1.81 ihickson 1352: </li>
1.4 ihickson 1353:
1354: <li>
1.81 ihickson 1355:
1356: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1357: worker such that no sooner than it stops being either a
1358: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1359: worker</a>, and no later than it stops being a
1360: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1361: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1362: to true<!-- v2-onclose and <span title="queue a task">a task is
1.179 ihickson 1363: queued</span> to <span>fire a simple event</span> named <code
1.123 ihickson 1364: title="event-close">close</code> at <var title="">worker global
1365: scope</var>-->.</p>
1.81 ihickson 1366:
1367: </li>
1.9 ihickson 1368:
1369: <li>
1.7 ihickson 1370:
1.81 ihickson 1371: <p><strong>Suspending workers</strong>: Start monitoring the
1372: worker, such that whenever <var title="">worker global
1.115 ihickson 1373: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1374: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1375: agent suspends execution of script in that worker until such time
1.115 ihickson 1376: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1377: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1378: worker</a>.</p>
1.4 ihickson 1379:
1.81 ihickson 1380: </li>
1.68 ihickson 1381:
1382: <li>
1.4 ihickson 1383:
1.81 ihickson 1384: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1385: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1386: entry-point</i>, and let that run until it either returns, fails
1387: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1388: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1389: algorithms defined below.</p>
1390:
1.149 ihickson 1391: <!-- v2-onclose
1392: <p class="note">If the script gets aborted by the "<span>kill a
1393: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1394: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1395: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1396: for the <code title="message-close">close</code> event. The
1.149 ihickson 1397: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1398: events.</p>
1.149 ihickson 1399: -->
1.4 ihickson 1400:
1.81 ihickson 1401: </li>
1.4 ihickson 1402:
1.95 ihickson 1403: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1404: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1405: a dedicated worker), then enable the <span>port message
1406: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1407:
1.4 ihickson 1408: <li>
1.68 ihickson 1409:
1.115 ihickson 1410: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1411: 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 1412: to true.</p>
1.43 ihickson 1413:
1.81 ihickson 1414: </li>
1.4 ihickson 1415:
1416: <li>
1417:
1.81 ihickson 1418: <p>Run the oldest task on one of the <span>event loop</span>'s
1419: <span title="task queue">task queues</span>, if any. The user
1420: agent may pick any <span>task queue</span>.</p>
1421:
1.115 ihickson 1422: <p class="note">The handling of events or the execution of
1423: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1424: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1425: defined below.</p>
1.8 ihickson 1426:
1.81 ihickson 1427: </li>
1.4 ihickson 1428:
1429: <li>
1430:
1.81 ihickson 1431: <p>Remove the task run in the previous step, if any, from its
1432: <span>task queue</span>.</p>
1.4 ihickson 1433:
1.81 ihickson 1434: </li>
1.4 ihickson 1435:
1436: <li>
1.8 ihickson 1437:
1.81 ihickson 1438: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1439: <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 1440: to false, then jump back to the step above labeled <i>event
1441: loop</i>.</p>
1.8 ihickson 1442:
1.81 ihickson 1443: </li>
1.8 ihickson 1444:
1445: <li>
1.71 ihickson 1446:
1.123 ihickson 1447: <p>If there are any outstanding transactions that have callbacks
1448: that involve <span title="concept-script">scripts</span> whose
1449: <span title="script's global object">global object</span> is the
1450: <var title="">worker global scope</var>, roll them back (without
1451: invoking any of the callbacks).</p>
1.50 ihickson 1452:
1.123 ihickson 1453: </li>
1454:
1455: <li>
1456:
1457: <p>Empty the <var title="">worker global scope</var>'s <span>list
1458: of active timeouts</span> and its <span>list of active
1459: intervals</span>.</p>
1.50 ihickson 1460:
1.81 ihickson 1461: </li>
1.50 ihickson 1462:
1.123 ihickson 1463: <!-- v2-onclose
1.81 ihickson 1464: <li>
1.50 ihickson 1465:
1.123 ihickson 1466: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1467: object associated with <var title="">worker global scope</var>,
1468: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1469: named <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1470:
1.81 ihickson 1471: </li>
1.123 ihickson 1472: -->
1.155 ihickson 1473: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1474: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1475: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1476: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1477: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1478: false, <span>queue a task</span> to <span>fire a simple
1.179 ihickson 1479: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1480: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1481: --><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 1482: true.</li>
1483:
1.123 ihickson 1484: <!-- v2-onclose
1485: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1486: a worker</span>" processing model defined above immediately starts
1487: running event listeners registered for the <code
1488: title="event-close">close</code> event, this time should not be
1489: zero — the idea is that the <code
1490: title="event-close">close</code> event can be used to clean up
1491: when shutting down unexpectedly.</p></li>
1492: -->
1.81 ihickson 1493:
1.115 ihickson 1494: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1495: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1496: queue">task queues</span><!-- v2-onclose other than the <code
1497: title="event-close">close</code> event that this algorithm just
1498: added-->, discard them without processing them.</li>
1.81 ihickson 1499:
1.123 ihickson 1500: <!-- v2-onclose
1.115 ihickson 1501: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1502: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1503: the script currently running in the worker.</p></li>
1504: -->
1.81 ihickson 1505:
1506: <li><p>Wait a user-agent-defined amount of time.</li>
1507:
1.123 ihickson 1508: <li><p>Abort the script currently running in the worker<!--
1509: v2-onclose (if any script is running, then it will be a handler for
1510: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1511:
1.155 ihickson 1512: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1513: processing model on a worker at any time, e.g. in response to user
1514: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1515: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1516: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1517: 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 1518: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1519: "<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 1520: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1521: true.</li>
1522:
1.115 ihickson 1523: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1524: queued in the <span>event loop</span>'s <span title="task
1525: queue">task queues</span>, discard them without processing
1526: them.</li>
1527:
1528: <li><p>Abort the script currently running in the worker.</li>
1529:
1.115 ihickson 1530: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1531: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1532: worker is a dedicated worker), then empty the <span>port message
1533: queue</span> of the port that the worker's implicit port is
1534: entangled with.</li>
1535:
1.155 ihickson 1536: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.186 ihickson 1537: <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 1538: worker's scripts, if the error did not occur while handling a
1539: previous script error, the user agent must <span>report the
1540: error</span> using the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code title="handler-WorkerGlobalScope-onerror"><a href="#handler-workerglobalscope-onerror">onerror</a></code>
1.205 ihickson 1541: attribute.
1542:
1.226 ihickson 1543: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1544:
1545: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1546: the error occurred while handling a previous script error, the error
1.215 ihickson 1547: may be reported to the user.
1.205 ihickson 1548:
1.226 ihickson 1549: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1550:
1551: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1552: the error occurred while handling a previous script error, the user
1.123 ihickson 1553: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1554: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1555: 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 1556: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1557: 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 1558: 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 1559: appropriately. The default action of this event depends on whether
1.115 ihickson 1560: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1561: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1562: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1563: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1.215 ihickson 1564: <em>that</em> worker. Otherwise, then the error may be reported
1.155 ihickson 1565: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1.233 ihickson 1566: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : <span>Event</span> {
1.147 ihickson 1567: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1568: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1569: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1570: 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 1571: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.190 ihickson 1572: method must initialize the event in a manner analogous to the
1573: 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 1574: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1575: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1576: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1577: attribute represents the line number where the error occurred in the
1.208 ihickson 1578: script.<h3 id="creating-workers"><span class="secno">4.7 </span>Creating workers</h3><h4 id="the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code><a href="#abstractworker">AbstractWorker</a></code> abstract interface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1579: interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1580: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1581: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.172 ihickson 1582: };
1.177 ihickson 1583: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handlers</span> (and their
1584: corresponding <span title="event handler event type">event handler
1585: event types</span>) that must be supported, as IDL attributes, by
1586: 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 1587: <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 1588: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.186 ihickson 1589: </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 1590: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1591: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1592:
1.174 ihickson 1593: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1594: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1595: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1596: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1597: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1598: algorithm to be run on the worker with with the object is
1.155 ihickson 1599: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1600: <code>MessagePort</code> associated with them. This port is part of
1601: a channel that is set up when the worker is created, but it is not
1602: exposed. This object must never be garbage collected before the
1.155 ihickson 1603: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1604: 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 1605: and <dfn
1606: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1607: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1608: must act as if, when invoked, it<!--/they (startConversation)-->
1609: immediately invoked the method of the same name on the port, with
1.177 ihickson 1610: the same arguments, and returned the same return value.<p>The following are the <span>event handlers</span> (and their
1611: corresponding <span title="event handler event type">event handler
1612: event types</span>) that must be supported, as IDL attributes, by
1613: 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 1614: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1615: </table><hr><p>When the <dfn id="dom-worker" title="dom-Worker"><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
1.216 ihickson 1616: user agent must run the following steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument relative to the <span>entry
1.133 ihickson 1617: script</span>'s <span title="script's base URL">base URL</span>,
1618: when the method is invoked.</li>
1.9 ihickson 1619:
1.81 ihickson 1620: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1621: exception.</li>
1.9 ihickson 1622:
1.167 ihickson 1623: <li>
1624:
1625: <p>If the <span>origin</span> of the resulting <span>absolute
1626: URL</span> is not the <span title="same origin">same</span> as the
1.216 ihickson 1627: origin of the <span>entry script</span>, then throw a
1.182 ihickson 1628: <code>SECURITY_ERR</code> exception.</p>
1.167 ihickson 1629:
1630: <p class="note">Thus, scripts must be external files with the same
1631: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1632: URL, and a <code>http:</code> page couldn't start workers using
1633: scripts with <code>http:</code> URLs.</p>
1634:
1635: </li>
1.9 ihickson 1636:
1.185 ihickson 1637: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1638: object. Let <var title="">worker global scope</var> be this new
1639: object.</li>
1.9 ihickson 1640:
1.115 ihickson 1641: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1642: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1643:
1.185 ihickson 1644: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1645: owned by the <span title="script's global object">global
1646: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1647: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1648: port</var>.</li>
1.9 ihickson 1649:
1.81 ihickson 1650: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1651:
1.185 ihickson 1652: <li><p><span>Create a new <code>MessagePort</code> object</span>
1653: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1654:
1.81 ihickson 1655: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1656:
1.81 ihickson 1657: <li><p><span>Entangle</span> <var title="">outside port</var> and
1658: <var title="">inside port</var>.</li>
1.50 ihickson 1659:
1.81 ihickson 1660: <li><p>Return <var title="">worker</var>, and run the following
1661: steps asynchronously.</li>
1.50 ihickson 1662:
1.204 ihickson 1663: <!-- (this is done by the "run a worker" algorithm)
1.126 ihickson 1664: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.204 ihickson 1665: queue</span>.</p></li>
1666: -->
1.50 ihickson 1667:
1.126 ihickson 1668: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1669: queue</span>.</li>
1.50 ihickson 1670:
1671: <li>
1.51 ihickson 1672:
1.123 ihickson 1673: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1674: <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 1675: constructor.</p>
1676:
1677: </li>
1678:
1679: <li>
1680:
1681: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1682: <var title="">worker global scope</var>'s list of <span>the
1683: worker's <code>Document</code>s</span></a> the
1684: <code>Document</code> objects in <var title="">docs</var>.</p>
1685:
1686: </li>
1687:
1688: <li>
1689:
1.192 ihickson 1690: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1691: of the <span title="concept-script">script</span> that invoked the
1692: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1693: are creating a nested worker), add <var title="">worker global
1694: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 1695: <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 1696: constructor.</p>
1697:
1698: </li>
1699:
1700: <li>
1701:
1.115 ihickson 1702: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 1703: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 1704: script that invoked the method as the <var title="">owner browsing
1.232 ihickson 1705: context</var>, with the <span>script's document</span> of the
1706: script that invoked the method as the <var title="">owner
1707: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1708: script</span> as the <var title="">owner origin</var>, and with
1709: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1710:
1.81 ihickson 1711: </li>
1.4 ihickson 1712:
1.155 ihickson 1713: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1714: object</span> is either a <code>Window</code> object or an object
1.186 ihickson 1715: 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 1716: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1717: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1718: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1719: attribute must return the value it was assigned by the object's
1720: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1721: 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 1722: constructor is invoked, the user agent must run the following
1.155 ihickson 1723: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1724:
1725: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1726: exception.</li>
1727:
1.159 ihickson 1728: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1729: resulting <span>absolute URL</span>.</li>
1730:
1731: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1732: argument, or the empty string if the second argument was
1733: omitted.</li>
1.159 ihickson 1734:
1.167 ihickson 1735: <li>
1736:
1737: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1738: not the <span title="same origin">same</span> as the origin of the
1.216 ihickson 1739: <span>entry script</span>, then throw a <code>SECURITY_ERR</code>
1.182 ihickson 1740: exception.</p>
1.167 ihickson 1741:
1742: <p class="note">Thus, scripts must be external files with the same
1743: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1744: URL, and a <code>http:</code> page couldn't start workers using
1745: scripts with <code>http:</code> URLs.</p>
1746:
1747: </li>
1.9 ihickson 1748:
1749: <li>
1750:
1.123 ihickson 1751: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1752: <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 1753: constructor.</p>
1754:
1755: </li>
1756:
1757: <li>
1758:
1.50 ihickson 1759: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1760:
1.155 ihickson 1761: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1762: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1763: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1764:
1.185 ihickson 1765: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1766: owned by the <span title="script's global object">global
1767: object</span> of the script that invoked the method. Let this be
1.123 ihickson 1768: the <var title="">outside port</var>.</li>
1.81 ihickson 1769:
1.115 ihickson 1770: <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 1771:
1.164 ihickson 1772: <li><p>Let <var title="">worker global scope</var> be
1773: null.</li>
1774:
1775: <li><p>If <var title="">name</var> is not the empty string and
1776: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1777: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1778: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1779: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1780: represents an <span>absolute URL</span> with the <span>same
1781: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1782: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1783:
1784: <li><p>Otherwise, if <var title="">name</var> is the empty string
1785: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1786: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1787: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.237 ihickson 1788: represents an <span>absolute URL</span> that is exactly equal to
1789: <var title="">scriptURL</var>, then let <var title="">worker
1790: global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1791: object.</li>
1.164 ihickson 1792:
1.9 ihickson 1793: <li>
1794:
1.164 ihickson 1795: <p>If <var title="">worker global scope</var> is not null, then
1796: run these steps:</p>
1.81 ihickson 1797:
1.164 ihickson 1798: <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 1799: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1800: exactly equal to <var title="">scriptURL</var>, then throw a
1801: <code>URL_MISMATCH_ERR</code> exception and abort all these
1802: steps.</li>
1.81 ihickson 1803:
1804: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1805:
1.185 ihickson 1806: <li><p><span>Create a new <code>MessagePort</code>
1807: object</span> owned by <var title="">worker global
1808: scope</var>. Let this be the <var title="">inside
1809: port</var>.</li>
1.81 ihickson 1810:
1811: <li><p><span>Entangle</span> <var title="">outside port</var>
1812: and <var title="">inside port</var>.</li>
1813:
1814: <li><p>Return <var title="">worker</var> and perform the next
1815: step asynchronously.</li>
1.9 ihickson 1816:
1.81 ihickson 1817: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1818: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1819: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1820: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1821: value is an array containing only the newly created port, and
1822: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1823:
1.123 ihickson 1824: <li>
1825:
1826: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1827: <var title="">worker global scope</var>'s list of <span>the
1828: worker's <code>Document</code>s</span></a> the
1829: <code>Document</code> objects in <var title="">docs</var>.</p>
1830:
1831: </li>
1832:
1.124 ihickson 1833: <li>
1834:
1.192 ihickson 1835: <p>If the <span title="script's global object">global
1836: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1837: that invoked the constructor is a
1838: <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
1839: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1840: object that is the <span title="script's global object">global
1841: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1842: that invoked the constructor.</p>
1843:
1844: </li>
1845:
1.81 ihickson 1846: <li><p>Abort all these steps.</li>
1.9 ihickson 1847:
1.155 ihickson 1848: </ol></li>
1.9 ihickson 1849:
1.185 ihickson 1850: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1851: object. Let <var title="">worker global scope</var> be this new
1852: object.</li>
1.9 ihickson 1853:
1.81 ihickson 1854: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1855:
1.115 ihickson 1856: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1857: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1858:
1.185 ihickson 1859: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.81 ihickson 1860: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1861:
1.81 ihickson 1862: <li><p><span>Entangle</span> <var title="">outside port</var> and
1863: <var title="">inside port</var>.</li>
1.9 ihickson 1864:
1.155 ihickson 1865: </ol></li>
1.28 ihickson 1866:
1.123 ihickson 1867: <li><p>Return <var title="">worker</var> and perform the remaining
1868: steps asynchronously.</li>
1.18 ihickson 1869:
1.81 ihickson 1870: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1871: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1872: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1873: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1874: is an array containing only the newly created port, and <span>queue
1875: a task</span> to dispatch the event at <var title="">worker global
1876: scope</var>.</li>
1.26 ihickson 1877:
1878: <li>
1.46 ihickson 1879:
1.123 ihickson 1880: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1881: <var title="">worker global scope</var>'s list of <span>the
1882: worker's <code>Document</code>s</span></a> the
1883: <code>Document</code> objects in <var title="">docs</var>.</p>
1884:
1885: </li>
1886:
1887: <li>
1888:
1.192 ihickson 1889: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1890: of the <span title="concept-script">script</span> that invoked the
1891: 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
1892: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1893: object that is the <span title="script's global object">global
1894: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1895: that invoked the constructor.</p>
1896:
1897: </li>
1898:
1899: <li>
1900:
1.159 ihickson 1901: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 1902: with the <span>script's browsing context</span> of the script that
1.159 ihickson 1903: invoked the method as the <var title="">owner browsing
1.232 ihickson 1904: context</var>, with the <span>script's document</span> of the
1905: script that invoked the method as the <var title="">owner
1906: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1907: script</span> as the <var title="">owner origin</var>, and with
1908: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1909:
1.60 ihickson 1910: </li>
1.81 ihickson 1911:
1.155 ihickson 1912: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1913: object</span> is either a <code>Window</code> object or an object
1.155 ihickson 1914: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1915: <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 1916: interface <dfn id="workerutils">WorkerUtils</dfn> {
1917: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.210 ihickson 1918: readonly attribute <a href="#workernavigator">WorkerNavigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 1919: };
1.184 ihickson 1920: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1921: objects, etc) are not available to workers in this version of this
1.155 ihickson 1922: 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 1923: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1924: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1925: anything. Abort these steps.</li>
1926:
1927: <li><p><span title="resolve a url">Resolve</span> each
1928: argument.</li>
1929:
1930: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1931: exception.</li>
1932:
1933: <!--
1.67 ihickson 1934: <li><p>If any of the resulting <span title="absolute URL">absolute
1935: URLs</span> have an <span>origin</span> that is not the <span
1936: title="same origin">same</span> as the origin of the script that
1.182 ihickson 1937: invoked the method, then throw a <code>SECURITY_ERR</code>
1938: exception.</p></li>
1.67 ihickson 1939: -->
1.26 ihickson 1940:
1941: <li>
1.81 ihickson 1942:
1.45 ihickson 1943: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 1944: resulting <span title="absolute URL">absolute URLs</span>, from
1.216 ihickson 1945: the <span>entry script</span>'s <span>origin</span>.</p> <!-- not
1.176 ihickson 1946: http-origin privacy sensitive -->
1.81 ihickson 1947:
1948: </li>
1.26 ihickson 1949:
1950: <li>
1951:
1.81 ihickson 1952: <p>For each argument in turn, in the order given, starting with
1953: the first one, run these substeps:</p>
1.26 ihickson 1954:
1.155 ihickson 1955: <ol><li>
1.26 ihickson 1956:
1.81 ihickson 1957: <p>Wait for the fetching attempt for the corresponding resource
1958: to complete.</p>
1.60 ihickson 1959:
1.81 ihickson 1960: <p>If the fetching attempt failed, throw a
1961: <code>NETWORK_ERR</code> exception and abort all these
1962: steps.</p>
1.45 ihickson 1963:
1.186 ihickson 1964: <p>If the attempt succeeds, then convert the script resource to
1965: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.85 ihickson 1966:
1967: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1968:
1.115 ihickson 1969: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1970: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1971: type.</p>
1.61 ihickson 1972:
1.81 ihickson 1973: </li>
1.26 ihickson 1974:
1.81 ihickson 1975: <li>
1.26 ihickson 1976:
1.81 ihickson 1977: <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 1978: same global object, browsing context, URL character encoding,
1979: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 1980: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1981:
1.115 ihickson 1982: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1983: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1984: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1985: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1986:
1.199 ihickson 1987: <p>If it failed to parse, then throw an ECMAScript
1988: <code>SyntaxError</code> exception and abort all these
1989: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 1990:
1.81 ihickson 1991: <p>If an exception was raised or if the script was prematurely
1992: aborted, then abort all these steps, letting the exception or
1993: aborting continue to be processed by the script that called the
1.115 ihickson 1994: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 1995: method.</p>
1996:
1.115 ihickson 1997: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 1998: worker</a>" algorithms abort the script then abort all these
1999: steps.</p>
2000:
2001: </li>
2002:
1.155 ihickson 2003: </ol></li>
1.152 ihickson 2004:
1.210 ihickson 2005: </ol><h3 id="the-workernavigator-object"><span class="secno">5.2 </span>The <code><a href="#workernavigator">WorkerNavigator</a></code> object</h3><p>The <dfn id="dom-worker-navigator" title="dom-worker-navigator"><code>navigator</code></dfn> attribute
1.115 ihickson 2006: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1.210 ihickson 2007: the <code><a href="#workernavigator">WorkerNavigator</a></code> interface, which represents the
2008: identity and state of the user agent (the client):<pre class="idl">interface <dfn id="workernavigator">WorkerNavigator</dfn> {};
2009: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorID</span>;
2010: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorOnLine</span>;</pre><p>Objects implementing the <code><a href="#workernavigator">WorkerNavigator</a></code> interface
2011: also implement the <code>NavigatorID</code> and
2012: <code>NavigatorOnLine</code> interfaces.
1.205 ihickson 2013:
1.226 ihickson 2014: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2015:
1.210 ihickson 2016: <p>This <code><a href="#workernavigator">WorkerNavigator</a></code> interface must not exist if the
2017: interface's <span>relevant namespace object</span> is a
2018: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h3 id="apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</h3><p>The <code title="dom-opendatabase">openDatabase()</code> and
1.115 ihickson 2019: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.200 ihickson 2020: 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 2021: the global scope of scripts whose <span>script's global
2022: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 2023: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 2024: constructors defined by the XMLHttpRequest specifications, except
2025: that the <span>document response entity body</span> must always be
1.160 ihickson 2026: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
2027: <span>script's base URL</span>; the
2028: <span><code>XMLHttpRequest</code> origin</span> is the script's
2029: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 2030:
1.205 ihickson 2031: <li><p>The interface objects and constructors defined by this
2032: specification.</li>
1.119 ihickson 2033:
1.205 ihickson 2034: <li><p>Constructors defined by specifications that explicitly say
2035: that they should be visible when the <span>script's global
2036: object</span> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>, a
2037: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>, or an object implementing the
2038: <code><a href="#workerutils">WorkerUtils</a></code> interface; the interfaces of any objects
2039: with such constructors; and the interfaces of any objects made
2040: accessible through APIs exposed by those constructors or made
2041: accessible through interfaces to be implemented by any objects that
2042: are themselves accessible to scripts whose <span>script's global
2043: object</span> implements the <code><a href="#workerutils">WorkerUtils</a></code>
2044: interface.</li>
2045:
2046: </ul><p class="note">These requirements do not override the requirements
2047: defined by the Web IDL specification, in particular concerning the
2048: visibility of interfaces annotated with the <code title="">[NoInterfaceObject]</code> extended attribute.<h3 id="worker-locations"><span class="secno">5.5 </span>Worker locations</h3><pre class="idl">interface <dfn id="workerlocation">WorkerLocation</dfn> {
1.115 ihickson 2049: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
2050: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
2051: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
2052: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
2053: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
2054: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
2055: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
2056: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 2057: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
2058: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 2059: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 2060: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 2061: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 2062: <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>,
2063: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
2064: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
2065: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
1.163 ihickson 2066: follow the rules given for URL decomposition IDL attributes, with the
1.115 ihickson 2067: <span title="concept-uda-input">input</span> being the
1.81 ihickson 2068: <span>absolute URL</span> that the object represents (same as the
1.115 ihickson 2069: <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and
2070: the <span title="concept-uda-setter">common setter action</span>
1.205 ihickson 2071: being a no-op, since the attributes are defined to be readonly.
2072:
1.226 ihickson 2073: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2074:
1.209 ihickson 2075: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface must not exist if the
2076: interface's <span>relevant namespace object</span> is a
1.226 ihickson 2077: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a><h2 class="no-num" id="references">References</h2><!--REFS--><p>All references are normative unless marked "Non-normative".</p><!-- Dates are only included for standards older than the Web,
2078: because the newer ones keep changing. --><dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.153 ihickson 2079: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
2080: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
2081: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1.226 ihickson 2082: S. Byrnes. W3C.</dd>
1.153 ihickson 2083: <!--
2084: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
1.226 ihickson 2085: DOM Core</a></cite>, S. Pieters. W3C.</dd>
1.153 ihickson 2086: -->
2087:
1.152 ihickson 2088: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
2089: <!--
2090: <dd><cite><a
2091: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
2092: Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2093: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C.</dd>
1.152 ihickson 2094: -->
2095: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
2096: Object Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2097: D. Schepers. W3C.</dd>
1.152 ihickson 2098:
2099: <dt id="refsECMA262">[ECMA262]</dt>
2100: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1.226 ihickson 2101: Language Specification</a></cite>. ECMA.</dd>
1.152 ihickson 2102:
1.226 ihickson 2103: <dt id="refsHTML">[HTML]</dt>
2104: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML</a></cite>,
2105: I. Hickson. WHATWG.</dd>
1.152 ihickson 2106:
1.154 ihickson 2107: <dt id="refsRFC2119">[RFC2119]</dt>
2108: <dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
1.226 ihickson 2109: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF.</dd>
1.154 ihickson 2110:
2111: <dt id="refsWEBIDL">[WEBIDL]</dt>
2112: <!--
2113: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
1.226 ihickson 2114: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2115: -->
2116: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
1.226 ihickson 2117: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2118:
1.230 ihickson 2119: <dt id="refsWEBSQL">[WEBSQL]</dt>
2120: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web SQL
2121: Database</a></cite>, I. Hickson. W3C.</dd>
2122:
1.152 ihickson 2123: <dt id="refsXHR">[XHR]</dt>
2124: <!--
2125: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
1.226 ihickson 2126: Object</a></cite>, A. van Kesteren. W3C.</dd>
1.152 ihickson 2127: -->
1.160 ihickson 2128: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.226 ihickson 2129: A. van Kesteren. W3C.</dd>
1.152 ihickson 2130:
1.221 ihickson 2131: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2132:
2133: Aaron Boodman,
1.155 ihickson 2134: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2135: Anne van Kesteren,
2136: Ben Turner,
2137: Dmitry Titov,
1.96 ihickson 2138: Drew Wilson,
1.97 ihickson 2139: Jeremy Orlow,
1.81 ihickson 2140: Jonas Sicking,
2141: Justin James,
2142: Kevin Hakanson,
2143: Maciej Stachowiak,
2144: Michael Nordman,
2145: Mike Smith,
2146:
2147: and
2148:
2149: Philip Taylor
2150:
1.155 ihickson 2151: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2152: technology and whose experience has been a huge influence on this
1.155 ihickson 2153: specification.
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