Annotation of html5/workers/Overview.html, revision 1.270
1.242 ihickson 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"><!-- when publishing, change bits marked ZZZ --><html lang="en-US-x-Hixie"><title>Web Workers</title><style type="text/css">
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1.82 ihickson 76:
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1.82 ihickson 146:
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1.260 ihickson 185:
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1.266 ihickson 190:
1.218 ihickson 191: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><div class="head">
1.115 ihickson 192: <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 193: <h1>Web Workers</h1>
1.270 ! ihickson 194: <h2 class="no-num no-toc" id="editor-s-draft-7-december-2010">Editor's Draft 7 December 2010</h2>
1.218 ihickson 195: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 196: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 197: <dt>Latest Editor's Draft:</dt>
1.260 ihickson 198: <dd><a class="latest-link" href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 199: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 200: <dt>Previous Versions:</dt>
1.113 ihickson 201: <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 202: <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 203: <!-- :ZZZ -->
1.81 ihickson 204: <dt>Editors:</dt>
1.115 ihickson 205: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 206: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
1.234 ihickson 207: © 2010 <a href="http://www.w3.org/"><abbr title="World Wide
1.155 ihickson 208: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 209: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
210: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
211: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
212: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
213: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 214: use</a> rules apply.</p>
1.201 ihickson 215:
1.254 ihickson 216:
1.252 ihickson 217: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.255 ihickson 218: <p class="alt">The bulk of the text of this specification is also
1.254 ihickson 219: available in the WHATWG <a href="http://www.whatwg.org/specs/web-apps/current-work/complete.html#workers">Web Applications 1.0</a> specification, under a license that permits
220: reuse of the specification text.</p>
1.252 ihickson 221: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
222:
1.254 ihickson 223:
1.155 ihickson 224: </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 225: authors to spawn background workers running scripts in parallel to
226: their main page. This allows for thread-like operation with
1.212 ihickson 227: 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 228: time of its publication. Other documents may supersede this
229: document. A list of current W3C publications and the most recently
230: formally published revision of this technical report can be found in
1.115 ihickson 231: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.201 ihickson 232: 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 233: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 234: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 235: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 236:
237: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 238: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
239: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 240: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 241:
1.155 ihickson 242: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 243: stable. <strong>Implementors who are not taking part in the
244: discussions are likely to find the specification changing out from
245: under them in incompatible ways.</strong> Vendors interested in
246: implementing this specification before it eventually reaches the
247: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 248: 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 249: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
250: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 251: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 252: 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 253: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 254: 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 255: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
256: <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>
257: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
258: <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>
1.258 ihickson 259: </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 Applications
1.81 ihickson 260: Working Group</a> is the W3C working group responsible for this
261: specification's progress along the W3C Recommendation track.
1.270 ! ihickson 262: This specification is the 7 December 2010 Editor's Draft.
1.155 ihickson 263: </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
264: 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 265: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 266: 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 267: 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 268: any patent disclosures</a> made in connection with the deliverables
269: of the group; that page also includes instructions for disclosing a
270: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 271: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
272: Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
1.252 ihickson 273: 6 of the W3C Patent Policy</a>.<h2 class="no-num no-toc" id="contents">Table of Contents</h2>
1.81 ihickson 274: <!--begin-toc-->
1.115 ihickson 275: <ol class="toc">
276: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 277: <ol>
1.115 ihickson 278: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
279: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 280: <ol>
1.115 ihickson 281: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
282: <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>
283: <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 284: <li><a href="#shared-workers-introduction"><span class="secno">1.2.4 </span>Shared workers introduction</a></li>
285: <li><a href="#shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</a></li>
286: <li><a href="#delegation"><span class="secno">1.2.6 </span>Delegation</a></li>
287: <li><a href="#providing-libraries"><span class="secno">1.2.7 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 288: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 289: <ol>
1.148 ihickson 290: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
291: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
292: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
293: <ol>
294: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 295: <ol>
1.148 ihickson 296: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
297: <li><a href="#dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.1.2 </span>Dedicated workers and the <code>DedicatedWorkerGlobalScope</code> interface</a></li>
1.270 ! ihickson 298: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> interface</a></ol></li>
1.160 ihickson 299: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.186 ihickson 300: <li><a href="#the-event-loop"><span class="secno">4.3 </span>The event loop</a></li>
301: <li><a href="#the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</a></li>
302: <li><a href="#processing-model"><span class="secno">4.5 </span>Processing model</a></li>
303: <li><a href="#runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</a></li>
304: <li><a href="#creating-workers"><span class="secno">4.7 </span>Creating workers</a>
1.81 ihickson 305: <ol>
1.186 ihickson 306: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
307: <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>
308: <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 309: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 310: <ol>
1.148 ihickson 311: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
1.210 ihickson 312: <li><a href="#the-workernavigator-object"><span class="secno">5.2 </span>The <code>WorkerNavigator</code> object</a></li>
1.148 ihickson 313: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
314: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
315: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 316: <li><a class="no-num" href="#references">References</a></li>
317: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 318: <!--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
319: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 320: scripts that respond to clicks or other user interactions, and
321: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 322: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 323: relatively heavy-weight, and are not intended to be used in large
324: numbers. For example, it would be inappropriate to launch one worker
325: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 326: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
327: 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
328: 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
329: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
330: (naïvely) compute prime numbers, and progressively displays the
331: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 332: <html>
333: <head>
334: <title>Worker example: One-core computation</title>
335: </head>
336: <body>
337: <p>The highest prime number discovered so far is: <output id="result"></output></p>
338: <script>
1.50 ihickson 339: var worker = new Worker('worker.js');
340: worker.onmessage = function (event) {
1.54 ihickson 341: document.getElementById('result').textContent = event.data;
1.29 ihickson 342: };
1.81 ihickson 343: </script>
344: </body>
1.155 ihickson 345: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 346: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 347: representing that worker, which is used to communicate with the
1.177 ihickson 348: 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 349: search: while (true) {
350: n += 1;
351: for (var i = 2; i <= Math.sqrt(n); i += 1)
352: if (n % i == 0)
353: continue search;
354: // found a prime!
1.50 ihickson 355: postMessage(n);
1.155 ihickson 356: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 357: 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 358: 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 359: task is to listen for notifications from the server, and, when
360: appropriate, either add or remove data from the client-side
1.155 ihickson 361: database.<p>Since no communication occurs between the worker and the main
362: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 363: new Worker('worker.js');
1.155 ihickson 364: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 365: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 366: server.onmessage = function (event) {
367: // data is in the format "command key value"
1.54 ihickson 368: var data = event.data.split(' ');
1.31 ihickson 369: switch (data[0]) {
370: case '+':
371: database.transaction(function(tx) {
372: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
373: });
374: case '-':
375: database.transaction(function(tx) {
376: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
377: });
378: }
1.155 ihickson 379: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 380: mechanism and opens the local database (which, we presume, has been
381: created earlier). The worker then just listens for messages from the
382: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 383: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 384: this example online</a>. (This example will not actually function,
385: since the server does not actually exist and the database is not
1.155 ihickson 386: 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 387: fetching stock updates for at regular intervals, and one for
1.155 ihickson 388: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 389: <html>
390: <head>
391: <title>Worker example: Stock ticker</title>
392: <script>
1.33 ihickson 393: // TICKER
394: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 395: var ticker = new Worker('ticker.js');
1.33 ihickson 396:
397: // SEARCHER
1.50 ihickson 398: var searcher = new Worker('searcher.js');
1.33 ihickson 399: function search(query) {
1.50 ihickson 400: searcher.postMessage(query);
1.33 ihickson 401: }
402:
403: // SYMBOL SELECTION UI
404: function select(newSymbol) {
405: symbol = newSymbol;
1.50 ihickson 406: ticker.postMessage(symbol);
1.33 ihickson 407: }
1.81 ihickson 408: </script>
409: </head>
1.122 ihickson 410: <body onload="search('')">
1.81 ihickson 411: <p><output id="symbol"></output> <output id="value"></output></p>
412: <script>
1.50 ihickson 413: ticker.onmessage = function (event) {
1.54 ihickson 414: var data = event.data.split(' ');
1.33 ihickson 415: document.getElementById('symbol').textContent = data[0];
416: document.getElementById('value').textContent = data[1];
417: };
1.50 ihickson 418: ticker.postMessage(symbol);
1.81 ihickson 419: </script>
1.122 ihickson 420: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 421: <ul id="results"></ul>
422: <script>
1.50 ihickson 423: searcher.onmessage = function (event) {
1.54 ihickson 424: var data = event.data.split(' ');
1.33 ihickson 425: var results = document.getElementById('results');
426: while (results.hasChildNodes()) // clear previous results
427: results.removeChild(results.firstChild);
428: for (var i = 0; i < data.length; i += 1) {
429: // add a list item with a button for each result
430: var li = document.createElement('li');
431: var button = document.createElement('button');
432: button.value = data[i];
433: button.type = 'button';
434: button.onclick = function () { select(this.value); };
435: button.textContent = data[i];
436: li.appendChild(button);
437: results.appendChild(li);
438: }
439: };
1.81 ihickson 440: </script>
441: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
442: </body>
1.155 ihickson 443: </html></pre><p>The two workers use a common library for performing the actual
444: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 445: try {
446: var xhr = new XMLHttpRequest();
447: xhr.open('GET', url, false);
448: xhr.send();
449: return xhr.responseText;
450: } catch (e) {
451: return ''; // turn all errors into empty results
452: }
1.155 ihickson 453: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 454: var timer;
455: var symbol;
456: function update() {
1.50 ihickson 457: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 458: timer = setTimeout(update, 10000);
459: }
1.50 ihickson 460: onmessage = function (event) {
1.33 ihickson 461: if (timer)
462: clearTimeout(timer);
1.54 ihickson 463: symbol = event.data;
1.33 ihickson 464: update();
1.155 ihickson 465: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 466: onmessage = function (event) {
1.54 ihickson 467: postMessage(get('search.cgi?' + event.data));
1.238 ihickson 468: };</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
469: example. Shared workers use slightly different APIs, since each
470: worker can have multiple connections.<p>This first example shows how you connect to a worker and how a
471: worker can send a message back to the page when it connects to
1.239 ihickson 472: it. Received messages are displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
473: <title>Shared workers: demo 1</title>
474: <pre id="log">Log:</pre>
475: <script>
476: var worker = new SharedWorker('test.js');
477: var log = document.getElementById('log');
478: worker.port.onmessage = function(e) { // note: not worker.onmessage!
479: log.textContent += '\n' + e.data;
480: }
481: </script>
482: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
483: var port = e.ports[0];
484: port.postMessage('Hello World!');
485: }
1.259 ihickson 486: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/001/test.html">View this example online</a>.<hr><p>This second example extends the first one by changing two things:
1.238 ihickson 487: first, messages are received using <code title="">addEventListener()</code> instead of an <span title="event
488: handler IDL attributes">event handler IDL attribute</span>, and
489: second, a message is sent <em>to</em> the worker, causing the worker
490: to send another message in return. Received messages are again
1.239 ihickson 491: displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
1.240 ihickson 492: <title>Shared workers: demo 2</title>
1.239 ihickson 493: <pre id="log">Log:</pre>
494: <script>
495: var worker = new SharedWorker('test.js');
496: var log = document.getElementById('log');
1.240 ihickson 497: worker.port.addEventListener('message', function(e) {
1.239 ihickson 498: log.textContent += '\n' + e.data;
1.240 ihickson 499: }, false);
500: worker.port.start(); // note: need this when using addEventListener
501: worker.port.postMessage('ping');
1.239 ihickson 502: </script>
503: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
504: var port = e.ports[0];
505: port.postMessage('Hello World!');
1.240 ihickson 506: port.onmessage = function(e) {
507: port.postMessage('pong'); // not e.ports[0].postMessage!
508: // e.target.postMessage('pong'); would work also
509: }
1.239 ihickson 510: }
1.259 ihickson 511: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/002/test.html">View this example online</a>.<hr><p>Finally, the example is extended to show how two pages can
1.238 ihickson 512: connect to the same worker; in this case, the second page is merely
513: in an <code>iframe</code> on the first page, but the same principle
514: would apply to an entirely separate page in a separate
1.239 ihickson 515: <span>top-level browsing context</span>.<p>Here is the outer HTML page:<pre><!DOCTYPE HTML>
516: <title>Shared workers: demo 3</title>
517: <pre id="log">Log:</pre>
518: <script>
519: var worker = new SharedWorker('test.js');
520: var log = document.getElementById('log');
521: worker.port.addEventListener('message', function(e) {
522: log.textContent += '\n' + e.data;
523: }, false);
524: worker.port.start();
525: worker.port.postMessage('ping');
526: </script>
527: <iframe src="inner.html"></iframe>
528: </pre><p>Here is the inner HTML page:<pre><!DOCTYPE HTML>
529: <title>Shared workers: demo 3 inner frame</title>
530: <pre id=log>Inner log:</pre>
531: <script>
532: var worker = new SharedWorker('test.js');
533: var log = document.getElementById('log');
534: worker.port.onmessage = function(e) {
535: log.textContent += '\n' + e.data;
536: }
537: </script>
538: </pre><p>Here is the JavaScript worker:<pre>var count = 0;
539: onconnect = function(e) {
540: count += 1;
541: var port = e.ports[0];
542: port.postMessage('Hello World! You are connection #' + count);
543: port.onmessage = function(e) {
544: port.postMessage('pong');
545: }
546: }
1.259 ihickson 547: </pre><p><a href="http://www.whatwg.org/demos/workers/shared/003/test.html">View this example online</a>.<h4 id="shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</h4><p><i>This section is non-normative.</i><p>In this example, multiple windows (viewers) can be opened that
1.81 ihickson 548: are all viewing the same map. All the windows share the same map
549: information, with a single worker coordinating all the viewers. Each
550: viewer can move around independently, but if they set any data on
1.155 ihickson 551: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
552: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 553: <html>
554: <head>
555: <title>Workers example: Multiviewer</title>
556: <script>
1.36 ihickson 557: function openViewer() {
558: window.open('viewer.html');
559: }
1.81 ihickson 560: </script>
561: </head>
562: <body>
563: <p><button type=button onclick="openViewer()">Open a new
564: viewer</button></p>
565: <p>Each viewer opens in a new window. You can have as many viewers
566: as you like, they all view the same data.</p>
567: </body>
1.155 ihickson 568: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 569: <html>
570: <head>
571: <title>Workers example: Multiviewer viewer</title>
572: <script>
1.50 ihickson 573: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 574:
575: // CONFIGURATION
576: function configure(event) {
1.54 ihickson 577: if (event.data.substr(0, 4) != 'cfg ') return;
578: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 579: // update display to mention our name is name
580: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
581: // no longer need this listener
1.43 ihickson 582: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 583: }
1.53 ihickson 584: worker.port.addEventListener('message', configure, false);
1.36 ihickson 585:
586: // MAP
587: function paintMap(event) {
1.54 ihickson 588: if (event.data.substr(0, 4) != 'map ') return;
589: var data = event.data.substr(4).split(',');
1.36 ihickson 590: // display tiles data[0] .. data[8]
591: var canvas = document.getElementById('map');
592: var context = canvas.getContext('2d');
593: for (var y = 0; y < 3; y += 1) {
594: for (var x = 0; x < 3; x += 1) {
595: var tile = data[y * 3 + x];
596: if (tile == '0')
597: context.fillStyle = 'green';
598: else
599: context.fillStyle = 'maroon';
600: fillRect(x * 50, y * 50, 50, 50);
601: }
602: }
603: }
1.53 ihickson 604: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 605:
606: // PUBLIC CHAT
607: function updatePublicChat(event) {
1.54 ihickson 608: if (event.data.substr(0, 4) != 'txt ') return;
609: var name = event.data.substr(4).split(' ', 1);
610: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 611: // display "<name> message" in public chat
1.36 ihickson 612: var dialog = document.getElementById('public');
613: var dt = document.createElement('dt');
614: dt.textContent = name;
615: dialog.appendChild(dt);
616: var dd = document.createElement('dd');
617: dd.textContent = message;
618: dialog.appendChild(dd);
619: }
1.53 ihickson 620: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 621:
622: // PRIVATE CHAT
623: function startPrivateChat(event) {
1.54 ihickson 624: if (event.data.substr(0, 4) != 'msg ') return;
625: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 626: var port = event.ports[0];
1.36 ihickson 627: // display a private chat UI
628: var ul = document.getElementById('private');
629: var li = document.createElement('li');
630: var h3 = document.createElement('h3');
631: h3.textContent = 'Private chat with ' + name;
632: li.appendChild(h3);
633: var dialog = document.createElement('dialog');
634: var addMessage = function(name, message) {
635: var dt = document.createElement('dt');
636: dt.textContent = name;
637: dialog.appendChild(dt);
638: var dd = document.createElement('dd');
639: dd.textContent = message;
640: dialog.appendChild(dd);
641: };
642: port.onmessage = function (event) {
1.54 ihickson 643: addMessage(name, event.data);
1.36 ihickson 644: };
645: li.appendChild(dialog);
646: var form = document.createElement('form');
647: var p = document.createElement('p');
648: var input = document.createElement('input');
649: input.size = 50;
650: p.appendChild(input);
651: p.appendChild(document.createTextNode(' '));
652: var button = document.createElement('button');
653: button.textContent = 'Post';
654: p.appendChild(button);
655: form.onsubmit = function () {
656: port.postMessage(input.value);
657: addMessage('me', input.value);
658: input.value = '';
659: return false;
660: };
661: form.appendChild(p);
662: li.appendChild(form);
663: }
1.53 ihickson 664: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 665:
666: worker.port.start();
1.81 ihickson 667: </script>
668: </head>
669: <body>
670: <h1>Viewer</h1>
671: <h2>Map</h2>
672: <p><canvas id="map" height=150 width=150></canvas></p>
673: <p>
674: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
675: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
676: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
677: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
678: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
679: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
680: </p>
681: <h2>Public Chat</h2>
682: <dialog id="public"></dialog>
683: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
684: <p>
685: <input type="text" name="message" size="50">
686: <button>Post</button>
687: </p>
688: </form>
689: <h2>Private Chat</h2>
690: <ul id="private"></ul>
691: </body>
692: </html>
1.155 ihickson 693: </pre><p>There are several key things worth noting about the way the
694: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 695: processing function, the code here attaches multiple event
696: listeners, each one performing a quick check to see if it is
697: relevant for the message. In this example it doesn't make much
698: difference, but if multiple authors wanted to collaborate using a
699: single port to communicate with a worker, it would allow for
700: independent code instead of changes having to all be made to a
1.155 ihickson 701: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 702: unregister specific listeners when you are done with them, as is
703: done with the <code title="">configure()</code> method in this
1.155 ihickson 704: example.<p>Finally, the worker:<pre>
705: var nextName = 0;
1.36 ihickson 706: function getNextName() {
707: // this could use more friendly names
708: // but for now just return a number
709: return nextName++;
710: }
711:
712: var map = [
713: [0, 0, 0, 0, 0, 0, 0],
714: [1, 1, 0, 1, 0, 1, 1],
715: [0, 1, 0, 1, 0, 0, 0],
716: [0, 1, 0, 1, 0, 1, 1],
717: [0, 0, 0, 1, 0, 0, 0],
718: [1, 0, 0, 1, 1, 1, 1],
719: [1, 1, 0, 1, 1, 0, 1],
720: ];
721:
722: function wrapX(x) {
723: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 724: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 725: return x;
726: }
727:
728: function wrapY(y) {
729: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 730: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 731: return y;
732: }
733:
1.50 ihickson 734: function sendMapData(callback) {
1.36 ihickson 735: var data = '';
736: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
737: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
738: if (data != '')
739: data += ',';
740: data += map[y][x];
741: }
742: }
1.50 ihickson 743: callback('map ' + data);
1.36 ihickson 744: }
745:
746: var viewers = {};
747: onconnect = function (event) {
1.84 ihickson 748: event.ports[0]._name = getNextName();
749: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
750: viewers[event.ports[0]._name] = event.port._data;
751: event.ports[0].postMessage('cfg ' + name);
752: event.ports[0].onmessage = getMessage;
753: sendMapData(event.ports[0].postMessage);
1.36 ihickson 754: };
755:
756: function getMessage(event) {
1.54 ihickson 757: switch (event.data.substr(0, 4)) {
1.36 ihickson 758: case 'mov ':
1.54 ihickson 759: var direction = event.data.substr(4);
1.36 ihickson 760: var dx = 0;
761: var dy = 0;
762: switch (direction) {
763: case 'up': dy = -1; break;
764: case 'down': dy = 1; break;
765: case 'left': dx = -1; break;
766: case 'right': dx = 1; break;
767: }
768: event.target._data.x = wrapX(event.target._data.x + dx);
769: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 770: sendMapData(event.target.postMessage);
1.36 ihickson 771: break;
772: case 'set ':
1.54 ihickson 773: var value = event.data.substr(4);
1.36 ihickson 774: map[event.target._data.y][event.target._data.x] = value;
775: for (var viewer in viewers)
1.50 ihickson 776: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 777: break;
778: case 'txt ':
779: var name = event.target._name;
1.54 ihickson 780: var message = event.data.substr(4);
1.36 ihickson 781: for (var viewer in viewers)
782: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
783: break;
784: case 'msg ':
785: var party1 = event._data;
1.54 ihickson 786: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 787: if (party2) {
788: var channel = new MessageChannel();
1.84 ihickson 789: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
790: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 791: }
792: break;
793: }
1.155 ihickson 794: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 795: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 796: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 797: "msg" message from one viewer naming another viewer, it sets up a
798: direct connection between the two, so that the two viewers can
799: communicate directly without the worker having to proxy all the
1.238 ihickson 800: 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 801: performance is to split computationally expensive tasks amongst
802: multiple workers. In this example, a computationally expensive task
803: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 804: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 805: <html>
806: <head>
1.203 ihickson 807: <title>Worker example: Multicore computation</title>
1.81 ihickson 808: </head>
809: <body>
1.203 ihickson 810: <p>Result: <output id="result"></output></p>
1.81 ihickson 811: <script>
1.50 ihickson 812: var worker = new Worker('worker.js');
813: worker.onmessage = function (event) {
1.54 ihickson 814: document.getElementById('result').textContent = event.data;
1.40 ihickson 815: };
1.81 ihickson 816: </script>
817: </body>
1.155 ihickson 818: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 819: var num_workers = 10;
820: var items_per_worker = 1000000;
821:
822: // start the workers
823: var result = 0;
824: var pending_workers = num_workers;
825: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 826: var worker = new Worker('core.js');
827: worker.postMessage(i * items_per_worker);
828: worker.postMessage((i+1) * items_per_worker);
829: worker.onmessage = storeResult;
1.40 ihickson 830: }
831:
832: // handle the results
833: function storeResult(event) {
1.54 ihickson 834: result += 1*event.data;
1.40 ihickson 835: pending_workers -= 1;
836: if (pending_workers <= 0)
1.50 ihickson 837: postMessage(result); // finished!
1.155 ihickson 838: }</pre><p>It consists of a loop to start the subworkers, and then a handler
839: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 840: onmessage = getStart;
1.40 ihickson 841: function getStart(event) {
1.54 ihickson 842: start = 1*event.data;
1.40 ihickson 843: onmessage = getEnd;
844: }
845:
846: var end;
847: function getEnd(event) {
1.54 ihickson 848: end = 1*event.data;
1.40 ihickson 849: onmessage = null;
1.66 ihickson 850: work();
1.40 ihickson 851: }
852:
1.66 ihickson 853: function work() {
1.40 ihickson 854: var result = 0;
855: for (var i = start; i < end; i += 1) {
856: // perform some complex calculation here
857: result += 1;
858: }
1.50 ihickson 859: postMessage(result);
860: close();
1.155 ihickson 861: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 862: for the range of numbers thus specified, and then report the result
1.238 ihickson 863: 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 864: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 865:
866: <dd>Takes a port, on which it will send two messages, first the
867: public key and then the private key.</dd>
868:
869: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
870:
871: <dd>Takes a port, to which any number of messages can be sent, the
872: first giving the public key, and the remainder giving the
873: plaintext, each of which is encrypted and then sent on that same
874: channel as the cyphertext. The user can close the port when it is
875: done encrypting content.</dd>
876:
877: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
878:
879: <dd>Takes a port, to which any number of messages can be sent, the
880: first giving the private key, and the remainder giving the
881: cyphertext, each of which is decrypted and then sent on that same
882: channel as the plaintext. The user can close the port when it is
883: done decrypting content.</dd>
1.49 ihickson 884:
1.155 ihickson 885: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 886: if (e.data == "genkeys")
1.84 ihickson 887: genkeys(e.ports[0]);
1.54 ihickson 888: else if (e.data == "encrypt")
1.84 ihickson 889: encrypt(e.ports[0]);
1.54 ihickson 890: else if (e.data == "decrypt")
1.84 ihickson 891: decrypt(e.ports[0]);
1.49 ihickson 892: }
893:
894: function genkeys(p) {
895: var keys = _generateKeyPair();
896: p.postMessage(keys[0]);
897: p.postMessage(keys[1]);
898: }
899:
900: function encrypt(p) {
901: var key, state = 0;
902: p.onmessage = function (e) {
903: if (state == 0) {
1.54 ihickson 904: key = e.data;
1.49 ihickson 905: state = 1;
906: } else {
1.54 ihickson 907: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 908: }
909: };
910: }
911:
912: function decrypt(p) {
913: var key, state = 0;
914: p.onmessage = function (e) {
915: if (state == 0) {
1.54 ihickson 916: key = e.data;
1.49 ihickson 917: state = 1;
918: } else {
1.54 ihickson 919: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 920: }
921: };
922: }
923:
1.50 ihickson 924: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 925: if ('onmessage' in this) // dedicated worker
1.50 ihickson 926: onmessage = handleMessage;
927: else // shared worker
928: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 929:
930:
931: // the "crypto" functions:
932:
933: function _generateKeyPair() {
934: return [Math.random(), Math.random()];
935: }
936:
937: function _encrypt(k, s) {
938: return 'encrypted-' + k + ' ' + s;
939: }
940:
941: function _decrypt(k, s) {
942: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 943: }</pre><p>Note that the crypto functions here are just stubs and don't do
944: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 945: <html>
946: <head>
947: <title>Worker example: Crypto library</title>
948: <script>
1.50 ihickson 949: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 950: function getKeys() {
951: var state = 0;
1.50 ihickson 952: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 953: if (state == 0)
1.54 ihickson 954: document.getElementById('public').value = e.data;
1.49 ihickson 955: else if (state == 1)
1.54 ihickson 956: document.getElementById('private').value = e.data;
1.49 ihickson 957: state += 1;
958: };
959: }
960: function enc() {
1.50 ihickson 961: var port = cryptoLib.startConversation("encrypt");
962: port.postMessage(document.getElementById('public').value);
963: port.postMessage(document.getElementById('input').value);
964: port.onmessage = function (e) {
1.54 ihickson 965: document.getElementById('input').value = e.data;
1.50 ihickson 966: port.close();
1.49 ihickson 967: };
968: }
969: function dec() {
1.50 ihickson 970: var port = cryptoLib.startConversation("decrypt");
971: port.postMessage(document.getElementById('private').value);
972: port.postMessage(document.getElementById('input').value);
973: port.onmessage = function (e) {
1.54 ihickson 974: document.getElementById('input').value = e.data;
1.50 ihickson 975: port.close();
1.49 ihickson 976: };
977: }
1.81 ihickson 978: </script>
979: <style>
1.49 ihickson 980: textarea { display: block; }
1.81 ihickson 981: </style>
982: </head>
983: <body onload="getKeys()">
984: <fieldset>
985: <legend>Keys</legend>
986: <p><label>Public Key: <textarea id="public"></textarea></label></p>
987: <p><label>Private Key: <textarea id="private"></textarea></label></p>
988: </fieldset>
989: <p><label>Input: <textarea id="input"></textarea></label></p>
990: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
991: </body>
1.155 ihickson 992: </html></pre><p>A later version of the API, though, might want to offload all the
993: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 994: if (e.data == "genkeys")
1.84 ihickson 995: genkeys(e.ports[0]);
1.54 ihickson 996: else if (e.data == "encrypt")
1.84 ihickson 997: encrypt(e.ports[0]);
1.54 ihickson 998: else if (e.data == "decrypt")
1.84 ihickson 999: decrypt(e.ports[0]);
1.49 ihickson 1000: }
1001:
1002: function genkeys(p) {
1.50 ihickson 1003: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 1004: generator.postMessage('', [p]);
1.49 ihickson 1005: }
1006:
1007: function encrypt(p) {
1008: p.onmessage = function (e) {
1.54 ihickson 1009: var key = e.data;
1.50 ihickson 1010: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 1011: encryptor.postMessage(key, [p]);
1.49 ihickson 1012: };
1013: }
1014:
1015: function encrypt(p) {
1016: p.onmessage = function (e) {
1.54 ihickson 1017: var key = e.data;
1.50 ihickson 1018: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 1019: decryptor.postMessage(key, [p]);
1.49 ihickson 1020: };
1021: }
1022:
1.50 ihickson 1023: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 1024: if ('onmessage' in this) // dedicated worker
1.50 ihickson 1025: onmessage = handleMessage;
1026: else // shared worker
1.84 ihickson 1027: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 1028: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 1029: var k = _generateKeyPair();
1.84 ihickson 1030: e.ports[0].postMessage(k[0]);
1031: e.ports[0].postMessage(k[1]);
1.49 ihickson 1032: close();
1033: }
1.50 ihickson 1034:
1035: function _generateKeyPair() {
1036: return [Math.random(), Math.random()];
1.155 ihickson 1037: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 1038: var key = e.data;
1.84 ihickson 1039: e.ports[0].onmessage = function (e) {
1.54 ihickson 1040: var s = e.data;
1.50 ihickson 1041: postMessage(_encrypt(key, s));
1.49 ihickson 1042: }
1.50 ihickson 1043: }
1044:
1045: function _encrypt(k, s) {
1046: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 1047: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 1048: var key = e.data;
1.84 ihickson 1049: e.ports[0].onmessage = function (e) {
1.54 ihickson 1050: var s = e.data;
1.50 ihickson 1051: postMessage(_decrypt(key, s));
1.49 ihickson 1052: }
1.50 ihickson 1053: }
1054:
1055: function _decrypt(k, s) {
1056: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 1057: }</pre><p>Notice how the users of the API don't have to even know that this
1058: is happening — the API hasn't changed; the library can
1.81 ihickson 1059: delegate to subworkers without changing its API, even though it is
1.155 ihickson 1060: 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 1061: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 1062: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 1063: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
1064: "OPTIONAL" in the normative parts of this document are to be
1065: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 1066: 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 1067: (such as "strip any leading space characters" or "return false and
1068: abort these steps") are to be interpreted with the meaning of the
1069: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 1070: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 1071: attributes, methods or objects. Such requirements are to be
1.155 ihickson 1072: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 1073: may be implemented in any manner, so long as the end result is
1074: equivalent. (In particular, the algorithms defined in this
1075: specification are intended to be easy to follow, and not intended to
1.155 ihickson 1076: be performant.)<p>The only conformance class defined by this specification is user
1077: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 1078: otherwise unconstrained inputs, e.g. to prevent denial of service
1079: attacks, to guard against running out of memory, or to work around
1.229 ihickson 1080: platform-specific limitations.<p>When support for a feature is disabled (e.g. as an emergency
1081: measure to mitigate a security problem, or to aid in development, or
1082: for performance reasons), user agents must act as if they had no
1083: support for the feature whatsoever, and as if the feature was not
1084: mentioned in this specification. For example, if a particular
1085: feature is accessed via an attribute in a Web IDL interface, the
1086: attribute itself would be omitted from the objects that implement
1087: that interface — leaving the attribute on the object but
1088: 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 1089: specifications.<dl><dt>HTML</dt>
1.49 ihickson 1090:
1.81 ihickson 1091: <dd>
1.49 ihickson 1092:
1.226 ihickson 1093: <p>Many fundamental concepts from HTML are used by this
1094: specification. <a href="#refsHTML">[HTML]</a></p>
1.49 ihickson 1095:
1.81 ihickson 1096: </dd>
1.1 ihickson 1097:
1.81 ihickson 1098: <dt>WebIDL</dt>
1.1 ihickson 1099:
1100: <dd>
1101:
1.81 ihickson 1102: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 1103: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 1104:
1.81 ihickson 1105: </dd>
1.1 ihickson 1106:
1.155 ihickson 1107: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 1108: <code title="">Foo</code> is actually an interface, is sometimes
1109: used instead of the more accurate "an object implementing the
1.155 ihickson 1110: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1111: scripts in Web applications, and does not necessarily imply the
1112: existence of an actual <code>Document</code> object or of any other
1113: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 1114: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1115: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1116: <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 1117: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1118: 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 1119: workers. Dedicated workers, once created, and are linked to their
1120: creator; but message ports can be used to communicate from a
1121: dedicated worker to multiple other browsing contexts or
1122: workers. Shared workers, on the other hand, are named, and once
1123: created any script running in the same <span>origin</span> can
1.155 ihickson 1124: 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 1125: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1126: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1127:
1128: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1129: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1130: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1131: };
1.172 ihickson 1132: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
1133: <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 1134: 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 1135: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1136: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1137: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1138: 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 1139: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1140: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1141: have been added to the <span>event loop</span>'s <span title="task
1142: queue">task queues</span>.</p>
1143:
1144: <!-- v2-onclose
1145: <li><p><span>Queue a task</span> to <span>fire a simple
1.179 ihickson 1146: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1147: <code>WorkerGlobalScope</code> object.</p></li>
1148: -->
1.81 ihickson 1149:
1.115 ihickson 1150: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1151: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1152: true. (This prevents any further tasks from being queued.)</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
1.270 ! ihickson 1187: host</span> from which it was created.<h4 id="shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.1.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> interface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 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:
1.256 ihickson 1302: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>,
1303: with the <i>synchronous flag</i> set and the <i>force same-origin
1304: flag</i> set.</p> <!-- not http-origin privacy sensitive (looking
1305: forward to CORS) -->
1306:
1307: <p>If the attempt fails, then for each <code><a href="#worker">Worker</a></code> or
1308: <code><a href="#sharedworker">SharedWorker</a></code> object associated with <var title="">worker global scope</var>, <span>queue a task</span> to
1309: <span>fire a simple event</span> named <code title="event-error">error</code> at that object. Abort these
1310: steps.</p>
1.7 ihickson 1311:
1.264 ihickson 1312: <p>If the attempt succeeds, then let <var title="">source</var> be
1313: the script resource <span>decoded as UTF-8, with error
1314: handling</span>.
1315:
1316: <a href="#refsHTML">[HTML]</a>
1317:
1318: </p>
1.81 ihickson 1319:
1.68 ihickson 1320: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1321:
1.115 ihickson 1322: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1323: type of the script is ignored. Unlike with <code>script</code>
1324: elements, there is no way to override the type. It's always
1.170 ihickson 1325: assumed to be JavaScript.</p>
1.81 ihickson 1326:
1327: </li>
1.7 ihickson 1328:
1329: <li>
1.68 ihickson 1330:
1.115 ihickson 1331: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1332: created, as follows.</p>
1333:
1334: <p>Create a new <span>script execution environment</span>
1335: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1336:
1.68 ihickson 1337: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1338: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1339: entry-points</span>; set the <i>initial code entry-point</i> to
1340: the entry-point for any executable code to be immediately run.</p>
1341:
1342: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1343:
1344: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1345:
1.232 ihickson 1346: <p>Set the <span>script's document</span> to <var title="">owner
1347: document</var>.</p>
1348:
1.83 ihickson 1349: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1350: UTF-8. (This is just used for encoding non-ASCII characters in the
1351: query component of URLs.)</p>
1.68 ihickson 1352:
1353: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1354:
1.81 ihickson 1355: </li>
1.4 ihickson 1356:
1357: <li>
1.81 ihickson 1358:
1359: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1360: worker such that no sooner than it stops being either a
1361: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1362: worker</a>, and no later than it stops being a
1363: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1364: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1365: to true<!-- v2-onclose and <span title="queue a task">a task is
1.179 ihickson 1366: queued</span> to <span>fire a simple event</span> named <code
1.123 ihickson 1367: title="event-close">close</code> at <var title="">worker global
1368: scope</var>-->.</p>
1.81 ihickson 1369:
1370: </li>
1.9 ihickson 1371:
1372: <li>
1.7 ihickson 1373:
1.81 ihickson 1374: <p><strong>Suspending workers</strong>: Start monitoring the
1375: worker, such that whenever <var title="">worker global
1.115 ihickson 1376: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1377: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1378: agent suspends execution of script in that worker until such time
1.115 ihickson 1379: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1380: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1381: worker</a>.</p>
1.4 ihickson 1382:
1.81 ihickson 1383: </li>
1.68 ihickson 1384:
1385: <li>
1.4 ihickson 1386:
1.81 ihickson 1387: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1388: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1389: entry-point</i>, and let that run until it either returns, fails
1390: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1391: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1392: algorithms defined below.</p>
1393:
1.149 ihickson 1394: <!-- v2-onclose
1395: <p class="note">If the script gets aborted by the "<span>kill a
1396: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1397: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1398: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1399: for the <code title="message-close">close</code> event. The
1.149 ihickson 1400: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1401: events.</p>
1.149 ihickson 1402: -->
1.4 ihickson 1403:
1.81 ihickson 1404: </li>
1.4 ihickson 1405:
1.95 ihickson 1406: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1407: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1408: a dedicated worker), then enable the <span>port message
1409: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1410:
1.4 ihickson 1411: <li>
1.68 ihickson 1412:
1.115 ihickson 1413: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1414: 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 1415: to true.</p>
1.43 ihickson 1416:
1.81 ihickson 1417: </li>
1.4 ihickson 1418:
1419: <li>
1420:
1.81 ihickson 1421: <p>Run the oldest task on one of the <span>event loop</span>'s
1422: <span title="task queue">task queues</span>, if any. The user
1423: agent may pick any <span>task queue</span>.</p>
1424:
1.115 ihickson 1425: <p class="note">The handling of events or the execution of
1426: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1427: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1428: defined below.</p>
1.8 ihickson 1429:
1.81 ihickson 1430: </li>
1.4 ihickson 1431:
1432: <li>
1433:
1.248 ihickson 1434: <p>If the <span>storage mutex</span> is now owned by the worker's
1435: <span>event loop</span>, release it so that it is once again
1436: free.</p>
1437:
1438: </li>
1439:
1440: <li>
1441:
1442: <p>Remove the task just run in the earlier step, if any, from its
1.81 ihickson 1443: <span>task queue</span>.</p>
1.4 ihickson 1444:
1.81 ihickson 1445: </li>
1.4 ihickson 1446:
1447: <li>
1.8 ihickson 1448:
1.81 ihickson 1449: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1450: <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 1451: to false, then jump back to the step above labeled <i>event
1452: loop</i>.</p>
1.8 ihickson 1453:
1.81 ihickson 1454: </li>
1.8 ihickson 1455:
1456: <li>
1.71 ihickson 1457:
1.123 ihickson 1458: <p>If there are any outstanding transactions that have callbacks
1459: that involve <span title="concept-script">scripts</span> whose
1460: <span title="script's global object">global object</span> is the
1461: <var title="">worker global scope</var>, roll them back (without
1.258 ihickson 1462: invoking any of the callbacks). <a href="#refsWEBSQL">[WEBSQL]</a></p>
1.50 ihickson 1463:
1.123 ihickson 1464: </li>
1465:
1466: <li>
1467:
1468: <p>Empty the <var title="">worker global scope</var>'s <span>list
1469: of active timeouts</span> and its <span>list of active
1470: intervals</span>.</p>
1.50 ihickson 1471:
1.81 ihickson 1472: </li>
1.50 ihickson 1473:
1.247 ihickson 1474: <li>
1475:
1476: <p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1477: ports</a>.</p>
1478:
1479: </li>
1480:
1.123 ihickson 1481: <!-- v2-onclose
1.81 ihickson 1482: <li>
1.50 ihickson 1483:
1.123 ihickson 1484: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1485: object associated with <var title="">worker global scope</var>,
1486: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1487: named <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1488:
1.81 ihickson 1489: </li>
1.123 ihickson 1490: -->
1.155 ihickson 1491: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1492: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1493: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1494: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1495: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1496: false, <span>queue a task</span> to <span>fire a simple
1.179 ihickson 1497: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1498: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1499: --><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 1500: true.</li>
1501:
1.123 ihickson 1502: <!-- v2-onclose
1503: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1504: a worker</span>" processing model defined above immediately starts
1505: running event listeners registered for the <code
1506: title="event-close">close</code> event, this time should not be
1507: zero — the idea is that the <code
1508: title="event-close">close</code> event can be used to clean up
1509: when shutting down unexpectedly.</p></li>
1510: -->
1.81 ihickson 1511:
1.115 ihickson 1512: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1513: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1514: queue">task queues</span><!-- v2-onclose other than the <code
1515: title="event-close">close</code> event that this algorithm just
1516: added-->, discard them without processing them.</li>
1.81 ihickson 1517:
1.123 ihickson 1518: <!-- v2-onclose
1.115 ihickson 1519: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1520: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1521: the script currently running in the worker.</p></li>
1522: -->
1.81 ihickson 1523:
1524: <li><p>Wait a user-agent-defined amount of time.</li>
1525:
1.123 ihickson 1526: <li><p>Abort the script currently running in the worker<!--
1527: v2-onclose (if any script is running, then it will be a handler for
1528: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1529:
1.155 ihickson 1530: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1531: processing model on a worker at any time, e.g. in response to user
1532: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1533: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1534: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1535: 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 1536: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1537: "<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 1538: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1539: true.</li>
1540:
1.115 ihickson 1541: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1542: queued in the <span>event loop</span>'s <span title="task
1543: queue">task queues</span>, discard them without processing
1544: them.</li>
1545:
1546: <li><p>Abort the script currently running in the worker.</li>
1547:
1.115 ihickson 1548: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1549: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1550: worker is a dedicated worker), then empty the <span>port message
1551: queue</span> of the port that the worker's implicit port is
1552: entangled with.</li>
1553:
1.155 ihickson 1554: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.186 ihickson 1555: <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 1556: worker's scripts, if the error did not occur while handling a
1557: previous script error, the user agent must <span>report the
1558: 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 1559: attribute.
1560:
1.226 ihickson 1561: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1562:
1563: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1564: the error occurred while handling a previous script error, the error
1.215 ihickson 1565: may be reported to the user.
1.205 ihickson 1566:
1.226 ihickson 1567: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1568:
1569: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1570: the error occurred while handling a previous script error, the user
1.123 ihickson 1571: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1572: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1573: 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 1574: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1575: 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 1576: 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 1577: appropriately. The default action of this event depends on whether
1.115 ihickson 1578: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1579: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1580: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1581: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1.215 ihickson 1582: <em>that</em> worker. Otherwise, then the error may be reported
1.155 ihickson 1583: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1.233 ihickson 1584: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : <span>Event</span> {
1.147 ihickson 1585: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1586: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1587: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1588: 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 1589: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.190 ihickson 1590: method must initialize the event in a manner analogous to the
1591: 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 1592: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1593: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1594: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1595: attribute represents the line number where the error occurred in the
1.208 ihickson 1596: 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]
1597: interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1598: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1599: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.172 ihickson 1600: };
1.177 ihickson 1601: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handlers</span> (and their
1602: corresponding <span title="event handler event type">event handler
1603: event types</span>) that must be supported, as IDL attributes, by
1604: 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 1605: <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 1606: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.186 ihickson 1607: </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 1608: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1609: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1610:
1.174 ihickson 1611: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1612: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1613: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1614: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1615: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1616: algorithm to be run on the worker with with the object is
1.155 ihickson 1617: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1618: <code>MessagePort</code> associated with them. This port is part of
1619: a channel that is set up when the worker is created, but it is not
1620: exposed. This object must never be garbage collected before the
1.155 ihickson 1621: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1622: 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 1623: and <dfn
1624: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1625: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1626: must act as if, when invoked, it<!--/they (startConversation)-->
1627: immediately invoked the method of the same name on the port, with
1.177 ihickson 1628: the same arguments, and returned the same return value.<p>The following are the <span>event handlers</span> (and their
1629: corresponding <span title="event handler event type">event handler
1630: event types</span>) that must be supported, as IDL attributes, by
1631: 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 1632: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1633: </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 1634: 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 1635: script</span>'s <span title="script's base URL">base URL</span>,
1636: when the method is invoked.</li>
1.9 ihickson 1637:
1.81 ihickson 1638: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1639: exception.</li>
1.9 ihickson 1640:
1.167 ihickson 1641: <li>
1642:
1643: <p>If the <span>origin</span> of the resulting <span>absolute
1644: URL</span> is not the <span title="same origin">same</span> as the
1.216 ihickson 1645: origin of the <span>entry script</span>, then throw a
1.182 ihickson 1646: <code>SECURITY_ERR</code> exception.</p>
1.167 ihickson 1647:
1648: <p class="note">Thus, scripts must be external files with the same
1.269 ihickson 1649: scheme as the original page: you can't load a script from a <span title="data protocol"><code title="">data:</code> URL</span> or
1650: <span title="javascript protocol"><code title="">javascript:</code> URL</span>, and an <code>http:</code>
1651: page couldn't start workers using scripts with <code>http:</code>
1652: URLs.</p>
1.167 ihickson 1653:
1654: </li>
1.9 ihickson 1655:
1.185 ihickson 1656: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1657: object. Let <var title="">worker global scope</var> be this new
1658: object.</li>
1.9 ihickson 1659:
1.115 ihickson 1660: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1661: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1662:
1.185 ihickson 1663: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1664: owned by the <span title="script's global object">global
1665: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1666: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1667: port</var>.</li>
1.9 ihickson 1668:
1.81 ihickson 1669: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1670:
1.185 ihickson 1671: <li><p><span>Create a new <code>MessagePort</code> object</span>
1672: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1673:
1.81 ihickson 1674: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1675:
1.81 ihickson 1676: <li><p><span>Entangle</span> <var title="">outside port</var> and
1677: <var title="">inside port</var>.</li>
1.50 ihickson 1678:
1.81 ihickson 1679: <li><p>Return <var title="">worker</var>, and run the following
1680: steps asynchronously.</li>
1.50 ihickson 1681:
1.204 ihickson 1682: <!-- (this is done by the "run a worker" algorithm)
1.126 ihickson 1683: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.204 ihickson 1684: queue</span>.</p></li>
1685: -->
1.50 ihickson 1686:
1.126 ihickson 1687: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1688: queue</span>.</li>
1.50 ihickson 1689:
1690: <li>
1.51 ihickson 1691:
1.123 ihickson 1692: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1693: <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 1694: constructor.</p>
1695:
1696: </li>
1697:
1698: <li>
1699:
1700: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1701: <var title="">worker global scope</var>'s list of <span>the
1702: worker's <code>Document</code>s</span></a> the
1703: <code>Document</code> objects in <var title="">docs</var>.</p>
1704:
1705: </li>
1706:
1707: <li>
1708:
1.192 ihickson 1709: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1710: of the <span title="concept-script">script</span> that invoked the
1711: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1712: are creating a nested worker), add <var title="">worker global
1713: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 1714: <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 1715: constructor.</p>
1716:
1717: </li>
1718:
1719: <li>
1720:
1.115 ihickson 1721: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 1722: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 1723: script that invoked the method as the <var title="">owner browsing
1.232 ihickson 1724: context</var>, with the <span>script's document</span> of the
1725: script that invoked the method as the <var title="">owner
1726: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1727: script</span> as the <var title="">owner origin</var>, and with
1728: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1729:
1.81 ihickson 1730: </li>
1.4 ihickson 1731:
1.155 ihickson 1732: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1733: object</span> is either a <code>Window</code> object or an object
1.186 ihickson 1734: 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 1735: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1736: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1737: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1738: attribute must return the value it was assigned by the object's
1739: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1740: 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 1741: constructor is invoked, the user agent must run the following
1.155 ihickson 1742: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1743:
1744: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1745: exception.</li>
1746:
1.159 ihickson 1747: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1748: resulting <span>absolute URL</span>.</li>
1749:
1750: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1751: argument, or the empty string if the second argument was
1752: omitted.</li>
1.159 ihickson 1753:
1.167 ihickson 1754: <li>
1755:
1756: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1757: not the <span title="same origin">same</span> as the origin of the
1.216 ihickson 1758: <span>entry script</span>, then throw a <code>SECURITY_ERR</code>
1.182 ihickson 1759: exception.</p>
1.167 ihickson 1760:
1761: <p class="note">Thus, scripts must be external files with the same
1.269 ihickson 1762: scheme as the original page: you can't load a script from a <span title="data protocol"><code title="">data:</code> URL</span> or
1763: <span title="javascript protocol"><code title="">javascript:</code> URL</span>, and a <code>http:</code>
1764: page couldn't start workers using scripts with <code>http:</code>
1765: URLs.</p>
1.167 ihickson 1766:
1767: </li>
1.9 ihickson 1768:
1769: <li>
1770:
1.123 ihickson 1771: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1772: <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 1773: constructor.</p>
1774:
1775: </li>
1776:
1777: <li>
1778:
1.50 ihickson 1779: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1780:
1.155 ihickson 1781: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1782: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1783: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1784:
1.185 ihickson 1785: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1786: owned by the <span title="script's global object">global
1787: object</span> of the script that invoked the method. Let this be
1.123 ihickson 1788: the <var title="">outside port</var>.</li>
1.81 ihickson 1789:
1.115 ihickson 1790: <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 1791:
1.164 ihickson 1792: <li><p>Let <var title="">worker global scope</var> be
1793: null.</li>
1794:
1795: <li><p>If <var title="">name</var> is not the empty string and
1796: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1797: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1798: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1799: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1800: represents an <span>absolute URL</span> with the <span>same
1801: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1802: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1803:
1804: <li><p>Otherwise, if <var title="">name</var> is the empty string
1805: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1806: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1807: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.237 ihickson 1808: represents an <span>absolute URL</span> that is exactly equal to
1809: <var title="">scriptURL</var>, then let <var title="">worker
1810: global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1811: object.</li>
1.164 ihickson 1812:
1.9 ihickson 1813: <li>
1814:
1.164 ihickson 1815: <p>If <var title="">worker global scope</var> is not null, then
1816: run these steps:</p>
1.81 ihickson 1817:
1.164 ihickson 1818: <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 1819: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1820: exactly equal to <var title="">scriptURL</var>, then throw a
1821: <code>URL_MISMATCH_ERR</code> exception and abort all these
1822: steps.</li>
1.81 ihickson 1823:
1824: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1825:
1.185 ihickson 1826: <li><p><span>Create a new <code>MessagePort</code>
1827: object</span> owned by <var title="">worker global
1828: scope</var>. Let this be the <var title="">inside
1829: port</var>.</li>
1.81 ihickson 1830:
1831: <li><p><span>Entangle</span> <var title="">outside port</var>
1832: and <var title="">inside port</var>.</li>
1833:
1834: <li><p>Return <var title="">worker</var> and perform the next
1835: step asynchronously.</li>
1.9 ihickson 1836:
1.81 ihickson 1837: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1838: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1839: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1840: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1841: value is an array containing only the newly created port, and
1842: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1843:
1.123 ihickson 1844: <li>
1845:
1846: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1847: <var title="">worker global scope</var>'s list of <span>the
1848: worker's <code>Document</code>s</span></a> the
1849: <code>Document</code> objects in <var title="">docs</var>.</p>
1850:
1851: </li>
1852:
1.124 ihickson 1853: <li>
1854:
1.192 ihickson 1855: <p>If the <span title="script's global object">global
1856: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1857: that invoked the constructor is a
1858: <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
1859: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1860: object that is the <span title="script's global object">global
1861: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1862: that invoked the constructor.</p>
1863:
1864: </li>
1865:
1.81 ihickson 1866: <li><p>Abort all these steps.</li>
1.9 ihickson 1867:
1.155 ihickson 1868: </ol></li>
1.9 ihickson 1869:
1.185 ihickson 1870: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1871: object. Let <var title="">worker global scope</var> be this new
1872: object.</li>
1.9 ihickson 1873:
1.81 ihickson 1874: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1875:
1.115 ihickson 1876: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1877: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1878:
1.185 ihickson 1879: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.81 ihickson 1880: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1881:
1.81 ihickson 1882: <li><p><span>Entangle</span> <var title="">outside port</var> and
1883: <var title="">inside port</var>.</li>
1.9 ihickson 1884:
1.155 ihickson 1885: </ol></li>
1.28 ihickson 1886:
1.123 ihickson 1887: <li><p>Return <var title="">worker</var> and perform the remaining
1888: steps asynchronously.</li>
1.18 ihickson 1889:
1.81 ihickson 1890: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1891: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1892: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1893: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1894: is an array containing only the newly created port, and <span>queue
1895: a task</span> to dispatch the event at <var title="">worker global
1896: scope</var>.</li>
1.26 ihickson 1897:
1898: <li>
1.46 ihickson 1899:
1.123 ihickson 1900: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1901: <var title="">worker global scope</var>'s list of <span>the
1902: worker's <code>Document</code>s</span></a> the
1903: <code>Document</code> objects in <var title="">docs</var>.</p>
1904:
1905: </li>
1906:
1907: <li>
1908:
1.192 ihickson 1909: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1910: of the <span title="concept-script">script</span> that invoked the
1911: 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
1912: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1913: object that is the <span title="script's global object">global
1914: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1915: that invoked the constructor.</p>
1916:
1917: </li>
1918:
1919: <li>
1920:
1.159 ihickson 1921: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 1922: with the <span>script's browsing context</span> of the script that
1.159 ihickson 1923: invoked the method as the <var title="">owner browsing
1.232 ihickson 1924: context</var>, with the <span>script's document</span> of the
1925: script that invoked the method as the <var title="">owner
1926: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1927: script</span> as the <var title="">owner origin</var>, and with
1928: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1929:
1.60 ihickson 1930: </li>
1.81 ihickson 1931:
1.155 ihickson 1932: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1933: object</span> is either a <code>Window</code> object or an object
1.155 ihickson 1934: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1935: <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 1936: interface <dfn id="workerutils">WorkerUtils</dfn> {
1937: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.210 ihickson 1938: readonly attribute <a href="#workernavigator">WorkerNavigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 1939: };
1.184 ihickson 1940: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1941: objects, etc) are not available to workers in this version of this
1.155 ihickson 1942: 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 1943: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1944: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1945: anything. Abort these steps.</li>
1946:
1947: <li><p><span title="resolve a url">Resolve</span> each
1948: argument.</li>
1949:
1950: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1951: exception.</li>
1952:
1953: <!--
1.67 ihickson 1954: <li><p>If any of the resulting <span title="absolute URL">absolute
1955: URLs</span> have an <span>origin</span> that is not the <span
1956: title="same origin">same</span> as the origin of the script that
1.182 ihickson 1957: invoked the method, then throw a <code>SECURITY_ERR</code>
1958: exception.</p></li>
1.67 ihickson 1959: -->
1.26 ihickson 1960:
1961: <li>
1.81 ihickson 1962:
1.45 ihickson 1963: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 1964: resulting <span title="absolute URL">absolute URLs</span>, from
1.256 ihickson 1965: the <span>entry script</span>'s <span>origin</span>, with the
1966: <i>synchronous flag</i> set.</p> <!-- not http-origin privacy
1967: sensitive -->
1.81 ihickson 1968:
1969: </li>
1.26 ihickson 1970:
1971: <li>
1972:
1.81 ihickson 1973: <p>For each argument in turn, in the order given, starting with
1974: the first one, run these substeps:</p>
1.26 ihickson 1975:
1.155 ihickson 1976: <ol><li>
1.26 ihickson 1977:
1.81 ihickson 1978: <p>Wait for the fetching attempt for the corresponding resource
1979: to complete.</p>
1.60 ihickson 1980:
1.81 ihickson 1981: <p>If the fetching attempt failed, throw a
1982: <code>NETWORK_ERR</code> exception and abort all these
1983: steps.</p>
1.45 ihickson 1984:
1.264 ihickson 1985: <p>If the attempt succeeds, then let <var title="">source</var> be
1986: the script resource <span>decoded as UTF-8, with error
1987: handling</span>.
1988:
1989: <a href="#refsHTML">[HTML]</a>
1990:
1991: </p>
1.85 ihickson 1992:
1993: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1994:
1.115 ihickson 1995: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1996: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1997: type.</p>
1.61 ihickson 1998:
1.81 ihickson 1999: </li>
1.26 ihickson 2000:
1.81 ihickson 2001: <li>
1.26 ihickson 2002:
1.81 ihickson 2003: <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 2004: same global object, browsing context, URL character encoding,
2005: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 2006: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 2007:
1.115 ihickson 2008: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 2009: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 2010: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
2011: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 2012:
1.199 ihickson 2013: <p>If it failed to parse, then throw an ECMAScript
2014: <code>SyntaxError</code> exception and abort all these
2015: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 2016:
1.81 ihickson 2017: <p>If an exception was raised or if the script was prematurely
2018: aborted, then abort all these steps, letting the exception or
2019: aborting continue to be processed by the script that called the
1.115 ihickson 2020: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 2021: method.</p>
2022:
1.115 ihickson 2023: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 2024: worker</a>" algorithms abort the script then abort all these
2025: steps.</p>
2026:
2027: </li>
2028:
1.155 ihickson 2029: </ol></li>
1.152 ihickson 2030:
1.210 ihickson 2031: </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 2032: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1.210 ihickson 2033: the <code><a href="#workernavigator">WorkerNavigator</a></code> interface, which represents the
2034: identity and state of the user agent (the client):<pre class="idl">interface <dfn id="workernavigator">WorkerNavigator</dfn> {};
2035: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorID</span>;
2036: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorOnLine</span>;</pre><p>Objects implementing the <code><a href="#workernavigator">WorkerNavigator</a></code> interface
2037: also implement the <code>NavigatorID</code> and
2038: <code>NavigatorOnLine</code> interfaces.
1.205 ihickson 2039:
1.226 ihickson 2040: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2041:
1.210 ihickson 2042: <p>This <code><a href="#workernavigator">WorkerNavigator</a></code> interface must not exist if the
2043: interface's <span>relevant namespace object</span> is a
2044: <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 2045: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.200 ihickson 2046: 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 2047: the global scope of scripts whose <span>script's global
2048: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 2049: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 2050: constructors defined by the XMLHttpRequest specifications, except
2051: that the <span>document response entity body</span> must always be
1.160 ihickson 2052: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
2053: <span>script's base URL</span>; the
2054: <span><code>XMLHttpRequest</code> origin</span> is the script's
2055: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 2056:
1.205 ihickson 2057: <li><p>The interface objects and constructors defined by this
2058: specification.</li>
1.119 ihickson 2059:
1.205 ihickson 2060: <li><p>Constructors defined by specifications that explicitly say
2061: that they should be visible when the <span>script's global
2062: object</span> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>, a
2063: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>, or an object implementing the
2064: <code><a href="#workerutils">WorkerUtils</a></code> interface; the interfaces of any objects
2065: with such constructors; and the interfaces of any objects made
2066: accessible through APIs exposed by those constructors or made
2067: accessible through interfaces to be implemented by any objects that
2068: are themselves accessible to scripts whose <span>script's global
2069: object</span> implements the <code><a href="#workerutils">WorkerUtils</a></code>
2070: interface.</li>
2071:
2072: </ul><p class="note">These requirements do not override the requirements
2073: defined by the Web IDL specification, in particular concerning the
2074: 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> {
1.263 ihickson 2075: // <span>URL decomposition IDL attributes</span>
1.115 ihickson 2076: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
2077: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
2078: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
2079: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
2080: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
2081: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
2082: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
2083: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 2084: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
2085: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 2086: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 2087: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 2088: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 2089: <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>,
2090: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
2091: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
1.263 ihickson 2092: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>.
2093: These must follow the rules given for <span>URL decomposition IDL
2094: attributes</span>, with the <span title="concept-uda-input">input</span> being the <span>absolute
2095: URL</span> that the object represents (same as the <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and the
2096: <span title="concept-uda-setter">common setter action</span> being a
2097: no-op, since the attributes are defined to be readonly.
1.205 ihickson 2098:
1.226 ihickson 2099: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2100:
1.209 ihickson 2101: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface must not exist if the
2102: interface's <span>relevant namespace object</span> is a
1.251 ihickson 2103: <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, because the newer ones keep changing. --><dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.153 ihickson 2104: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
2105: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
2106: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1.226 ihickson 2107: S. Byrnes. W3C.</dd>
1.153 ihickson 2108: <!--
2109: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
1.226 ihickson 2110: DOM Core</a></cite>, S. Pieters. W3C.</dd>
1.153 ihickson 2111: -->
2112:
1.152 ihickson 2113: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
2114: <!--
2115: <dd><cite><a
2116: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
2117: Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2118: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C.</dd>
1.152 ihickson 2119: -->
2120: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
2121: Object Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2122: D. Schepers. W3C.</dd>
1.152 ihickson 2123:
2124: <dt id="refsECMA262">[ECMA262]</dt>
2125: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1.226 ihickson 2126: Language Specification</a></cite>. ECMA.</dd>
1.152 ihickson 2127:
1.226 ihickson 2128: <dt id="refsHTML">[HTML]</dt>
2129: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML</a></cite>,
2130: I. Hickson. WHATWG.</dd>
1.152 ihickson 2131:
1.154 ihickson 2132: <dt id="refsRFC2119">[RFC2119]</dt>
1.265 ihickson 2133: <dd><cite><a href="http://tools.ietf.org/html/rfc2119">Key words for use in
1.226 ihickson 2134: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF.</dd>
1.154 ihickson 2135:
2136: <dt id="refsWEBIDL">[WEBIDL]</dt>
2137: <!--
2138: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
1.226 ihickson 2139: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2140: -->
2141: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
1.226 ihickson 2142: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2143:
1.230 ihickson 2144: <dt id="refsWEBSQL">[WEBSQL]</dt>
2145: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web SQL
2146: Database</a></cite>, I. Hickson. W3C.</dd>
2147:
1.152 ihickson 2148: <dt id="refsXHR">[XHR]</dt>
2149: <!--
2150: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
1.226 ihickson 2151: Object</a></cite>, A. van Kesteren. W3C.</dd>
1.152 ihickson 2152: -->
1.160 ihickson 2153: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.226 ihickson 2154: A. van Kesteren. W3C.</dd>
1.152 ihickson 2155:
1.221 ihickson 2156: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2157:
2158: Aaron Boodman,
1.155 ihickson 2159: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2160: Anne van Kesteren,
2161: Ben Turner,
2162: Dmitry Titov,
1.96 ihickson 2163: Drew Wilson,
1.97 ihickson 2164: Jeremy Orlow,
1.81 ihickson 2165: Jonas Sicking,
2166: Justin James,
2167: Kevin Hakanson,
2168: Maciej Stachowiak,
2169: Michael Nordman,
2170: Mike Smith,
2171:
2172: and
2173:
2174: Philip Taylor
2175:
1.155 ihickson 2176: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2177: technology and whose experience has been a huge influence on this
1.155 ihickson 2178: specification.
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