Annotation of html5/workers/Overview.html, revision 1.260
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 67:
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1.82 ihickson 143:
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1.260 ! ihickson 182:
1.218 ihickson 183: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><div class="head">
1.115 ihickson 184: <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 185: <h1>Web Workers</h1>
1.260 ! ihickson 186: <h2 class="no-num no-toc" id="editor-s-draft-9-august-2010">Editor's Draft 9 August 2010</h2>
1.218 ihickson 187: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 188: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 189: <dt>Latest Editor's Draft:</dt>
1.260 ! ihickson 190: <dd><a class="latest-link" href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 191: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 192: <dt>Previous Versions:</dt>
1.113 ihickson 193: <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 194: <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 195: <!-- :ZZZ -->
1.81 ihickson 196: <dt>Editors:</dt>
1.115 ihickson 197: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 198: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
1.234 ihickson 199: © 2010 <a href="http://www.w3.org/"><abbr title="World Wide
1.155 ihickson 200: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 201: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
202: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
203: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
204: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
205: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 206: use</a> rules apply.</p>
1.201 ihickson 207:
1.254 ihickson 208:
1.252 ihickson 209: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.255 ihickson 210: <p class="alt">The bulk of the text of this specification is also
1.254 ihickson 211: 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
212: reuse of the specification text.</p>
1.252 ihickson 213: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
214:
1.254 ihickson 215:
1.155 ihickson 216: </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 217: authors to spawn background workers running scripts in parallel to
218: their main page. This allows for thread-like operation with
1.212 ihickson 219: 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 220: time of its publication. Other documents may supersede this
221: document. A list of current W3C publications and the most recently
222: formally published revision of this technical report can be found in
1.115 ihickson 223: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.201 ihickson 224: 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 225: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 226: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 227: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 228:
229: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 230: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
231: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 232: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 233:
1.155 ihickson 234: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 235: stable. <strong>Implementors who are not taking part in the
236: discussions are likely to find the specification changing out from
237: under them in incompatible ways.</strong> Vendors interested in
238: implementing this specification before it eventually reaches the
239: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 240: 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 241: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
242: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 243: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 244: 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 245: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 246: 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 247: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
248: <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>
249: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
250: <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 251: </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 252: Working Group</a> is the W3C working group responsible for this
253: specification's progress along the W3C Recommendation track.
1.260 ! ihickson 254: This specification is the 9 August 2010 Editor's Draft.
1.155 ihickson 255: </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
256: 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 257: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 258: 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 259: 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 260: any patent disclosures</a> made in connection with the deliverables
261: of the group; that page also includes instructions for disclosing a
262: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 263: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
264: 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 265: 6 of the W3C Patent Policy</a>.<h2 class="no-num no-toc" id="contents">Table of Contents</h2>
1.81 ihickson 266: <!--begin-toc-->
1.115 ihickson 267: <ol class="toc">
268: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 269: <ol>
1.115 ihickson 270: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
271: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 272: <ol>
1.115 ihickson 273: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
274: <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>
275: <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 276: <li><a href="#shared-workers-introduction"><span class="secno">1.2.4 </span>Shared workers introduction</a></li>
277: <li><a href="#shared-state-using-a-shared-worker"><span class="secno">1.2.5 </span>Shared state using a shared worker</a></li>
278: <li><a href="#delegation"><span class="secno">1.2.6 </span>Delegation</a></li>
279: <li><a href="#providing-libraries"><span class="secno">1.2.7 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 280: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 281: <ol>
1.148 ihickson 282: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
283: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
284: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
285: <ol>
286: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 287: <ol>
1.148 ihickson 288: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
289: <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>
290: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> inteface</a></ol></li>
1.160 ihickson 291: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.186 ihickson 292: <li><a href="#the-event-loop"><span class="secno">4.3 </span>The event loop</a></li>
293: <li><a href="#the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</a></li>
294: <li><a href="#processing-model"><span class="secno">4.5 </span>Processing model</a></li>
295: <li><a href="#runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</a></li>
296: <li><a href="#creating-workers"><span class="secno">4.7 </span>Creating workers</a>
1.81 ihickson 297: <ol>
1.186 ihickson 298: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
299: <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>
300: <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 301: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 302: <ol>
1.148 ihickson 303: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
1.210 ihickson 304: <li><a href="#the-workernavigator-object"><span class="secno">5.2 </span>The <code>WorkerNavigator</code> object</a></li>
1.148 ihickson 305: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
306: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
307: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 308: <li><a class="no-num" href="#references">References</a></li>
309: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 310: <!--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
311: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 312: scripts that respond to clicks or other user interactions, and
313: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 314: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 315: relatively heavy-weight, and are not intended to be used in large
316: numbers. For example, it would be inappropriate to launch one worker
317: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 318: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
319: 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
320: 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
321: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
322: (naïvely) compute prime numbers, and progressively displays the
323: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 324: <html>
325: <head>
326: <title>Worker example: One-core computation</title>
327: </head>
328: <body>
329: <p>The highest prime number discovered so far is: <output id="result"></output></p>
330: <script>
1.50 ihickson 331: var worker = new Worker('worker.js');
332: worker.onmessage = function (event) {
1.54 ihickson 333: document.getElementById('result').textContent = event.data;
1.29 ihickson 334: };
1.81 ihickson 335: </script>
336: </body>
1.155 ihickson 337: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 338: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 339: representing that worker, which is used to communicate with the
1.177 ihickson 340: 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 341: search: while (true) {
342: n += 1;
343: for (var i = 2; i <= Math.sqrt(n); i += 1)
344: if (n % i == 0)
345: continue search;
346: // found a prime!
1.50 ihickson 347: postMessage(n);
1.155 ihickson 348: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 349: 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 350: 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 351: task is to listen for notifications from the server, and, when
352: appropriate, either add or remove data from the client-side
1.155 ihickson 353: database.<p>Since no communication occurs between the worker and the main
354: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 355: new Worker('worker.js');
1.155 ihickson 356: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 357: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 358: server.onmessage = function (event) {
359: // data is in the format "command key value"
1.54 ihickson 360: var data = event.data.split(' ');
1.31 ihickson 361: switch (data[0]) {
362: case '+':
363: database.transaction(function(tx) {
364: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
365: });
366: case '-':
367: database.transaction(function(tx) {
368: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
369: });
370: }
1.155 ihickson 371: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 372: mechanism and opens the local database (which, we presume, has been
373: created earlier). The worker then just listens for messages from the
374: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 375: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 376: this example online</a>. (This example will not actually function,
377: since the server does not actually exist and the database is not
1.155 ihickson 378: 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 379: fetching stock updates for at regular intervals, and one for
1.155 ihickson 380: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 381: <html>
382: <head>
383: <title>Worker example: Stock ticker</title>
384: <script>
1.33 ihickson 385: // TICKER
386: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 387: var ticker = new Worker('ticker.js');
1.33 ihickson 388:
389: // SEARCHER
1.50 ihickson 390: var searcher = new Worker('searcher.js');
1.33 ihickson 391: function search(query) {
1.50 ihickson 392: searcher.postMessage(query);
1.33 ihickson 393: }
394:
395: // SYMBOL SELECTION UI
396: function select(newSymbol) {
397: symbol = newSymbol;
1.50 ihickson 398: ticker.postMessage(symbol);
1.33 ihickson 399: }
1.81 ihickson 400: </script>
401: </head>
1.122 ihickson 402: <body onload="search('')">
1.81 ihickson 403: <p><output id="symbol"></output> <output id="value"></output></p>
404: <script>
1.50 ihickson 405: ticker.onmessage = function (event) {
1.54 ihickson 406: var data = event.data.split(' ');
1.33 ihickson 407: document.getElementById('symbol').textContent = data[0];
408: document.getElementById('value').textContent = data[1];
409: };
1.50 ihickson 410: ticker.postMessage(symbol);
1.81 ihickson 411: </script>
1.122 ihickson 412: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 413: <ul id="results"></ul>
414: <script>
1.50 ihickson 415: searcher.onmessage = function (event) {
1.54 ihickson 416: var data = event.data.split(' ');
1.33 ihickson 417: var results = document.getElementById('results');
418: while (results.hasChildNodes()) // clear previous results
419: results.removeChild(results.firstChild);
420: for (var i = 0; i < data.length; i += 1) {
421: // add a list item with a button for each result
422: var li = document.createElement('li');
423: var button = document.createElement('button');
424: button.value = data[i];
425: button.type = 'button';
426: button.onclick = function () { select(this.value); };
427: button.textContent = data[i];
428: li.appendChild(button);
429: results.appendChild(li);
430: }
431: };
1.81 ihickson 432: </script>
433: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
434: </body>
1.155 ihickson 435: </html></pre><p>The two workers use a common library for performing the actual
436: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 437: try {
438: var xhr = new XMLHttpRequest();
439: xhr.open('GET', url, false);
440: xhr.send();
441: return xhr.responseText;
442: } catch (e) {
443: return ''; // turn all errors into empty results
444: }
1.155 ihickson 445: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 446: var timer;
447: var symbol;
448: function update() {
1.50 ihickson 449: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 450: timer = setTimeout(update, 10000);
451: }
1.50 ihickson 452: onmessage = function (event) {
1.33 ihickson 453: if (timer)
454: clearTimeout(timer);
1.54 ihickson 455: symbol = event.data;
1.33 ihickson 456: update();
1.155 ihickson 457: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 458: onmessage = function (event) {
1.54 ihickson 459: postMessage(get('search.cgi?' + event.data));
1.238 ihickson 460: };</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
461: example. Shared workers use slightly different APIs, since each
462: worker can have multiple connections.<p>This first example shows how you connect to a worker and how a
463: worker can send a message back to the page when it connects to
1.239 ihickson 464: it. Received messages are displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
465: <title>Shared workers: demo 1</title>
466: <pre id="log">Log:</pre>
467: <script>
468: var worker = new SharedWorker('test.js');
469: var log = document.getElementById('log');
470: worker.port.onmessage = function(e) { // note: not worker.onmessage!
471: log.textContent += '\n' + e.data;
472: }
473: </script>
474: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
475: var port = e.ports[0];
476: port.postMessage('Hello World!');
477: }
1.259 ihickson 478: </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 479: first, messages are received using <code title="">addEventListener()</code> instead of an <span title="event
480: handler IDL attributes">event handler IDL attribute</span>, and
481: second, a message is sent <em>to</em> the worker, causing the worker
482: to send another message in return. Received messages are again
1.239 ihickson 483: displayed in a log.<p>Here is the HTML page:<pre><!DOCTYPE HTML>
1.240 ihickson 484: <title>Shared workers: demo 2</title>
1.239 ihickson 485: <pre id="log">Log:</pre>
486: <script>
487: var worker = new SharedWorker('test.js');
488: var log = document.getElementById('log');
1.240 ihickson 489: worker.port.addEventListener('message', function(e) {
1.239 ihickson 490: log.textContent += '\n' + e.data;
1.240 ihickson 491: }, false);
492: worker.port.start(); // note: need this when using addEventListener
493: worker.port.postMessage('ping');
1.239 ihickson 494: </script>
495: </pre><p>Here is the JavaScript worker:<pre>onconnect = function(e) {
496: var port = e.ports[0];
497: port.postMessage('Hello World!');
1.240 ihickson 498: port.onmessage = function(e) {
499: port.postMessage('pong'); // not e.ports[0].postMessage!
500: // e.target.postMessage('pong'); would work also
501: }
1.239 ihickson 502: }
1.259 ihickson 503: </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 504: connect to the same worker; in this case, the second page is merely
505: in an <code>iframe</code> on the first page, but the same principle
506: would apply to an entirely separate page in a separate
1.239 ihickson 507: <span>top-level browsing context</span>.<p>Here is the outer HTML page:<pre><!DOCTYPE HTML>
508: <title>Shared workers: demo 3</title>
509: <pre id="log">Log:</pre>
510: <script>
511: var worker = new SharedWorker('test.js');
512: var log = document.getElementById('log');
513: worker.port.addEventListener('message', function(e) {
514: log.textContent += '\n' + e.data;
515: }, false);
516: worker.port.start();
517: worker.port.postMessage('ping');
518: </script>
519: <iframe src="inner.html"></iframe>
520: </pre><p>Here is the inner HTML page:<pre><!DOCTYPE HTML>
521: <title>Shared workers: demo 3 inner frame</title>
522: <pre id=log>Inner log:</pre>
523: <script>
524: var worker = new SharedWorker('test.js');
525: var log = document.getElementById('log');
526: worker.port.onmessage = function(e) {
527: log.textContent += '\n' + e.data;
528: }
529: </script>
530: </pre><p>Here is the JavaScript worker:<pre>var count = 0;
531: onconnect = function(e) {
532: count += 1;
533: var port = e.ports[0];
534: port.postMessage('Hello World! You are connection #' + count);
535: port.onmessage = function(e) {
536: port.postMessage('pong');
537: }
538: }
1.259 ihickson 539: </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 540: are all viewing the same map. All the windows share the same map
541: information, with a single worker coordinating all the viewers. Each
542: viewer can move around independently, but if they set any data on
1.155 ihickson 543: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
544: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 545: <html>
546: <head>
547: <title>Workers example: Multiviewer</title>
548: <script>
1.36 ihickson 549: function openViewer() {
550: window.open('viewer.html');
551: }
1.81 ihickson 552: </script>
553: </head>
554: <body>
555: <p><button type=button onclick="openViewer()">Open a new
556: viewer</button></p>
557: <p>Each viewer opens in a new window. You can have as many viewers
558: as you like, they all view the same data.</p>
559: </body>
1.155 ihickson 560: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 561: <html>
562: <head>
563: <title>Workers example: Multiviewer viewer</title>
564: <script>
1.50 ihickson 565: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 566:
567: // CONFIGURATION
568: function configure(event) {
1.54 ihickson 569: if (event.data.substr(0, 4) != 'cfg ') return;
570: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 571: // update display to mention our name is name
572: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
573: // no longer need this listener
1.43 ihickson 574: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 575: }
1.53 ihickson 576: worker.port.addEventListener('message', configure, false);
1.36 ihickson 577:
578: // MAP
579: function paintMap(event) {
1.54 ihickson 580: if (event.data.substr(0, 4) != 'map ') return;
581: var data = event.data.substr(4).split(',');
1.36 ihickson 582: // display tiles data[0] .. data[8]
583: var canvas = document.getElementById('map');
584: var context = canvas.getContext('2d');
585: for (var y = 0; y < 3; y += 1) {
586: for (var x = 0; x < 3; x += 1) {
587: var tile = data[y * 3 + x];
588: if (tile == '0')
589: context.fillStyle = 'green';
590: else
591: context.fillStyle = 'maroon';
592: fillRect(x * 50, y * 50, 50, 50);
593: }
594: }
595: }
1.53 ihickson 596: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 597:
598: // PUBLIC CHAT
599: function updatePublicChat(event) {
1.54 ihickson 600: if (event.data.substr(0, 4) != 'txt ') return;
601: var name = event.data.substr(4).split(' ', 1);
602: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 603: // display "<name> message" in public chat
1.36 ihickson 604: var dialog = document.getElementById('public');
605: var dt = document.createElement('dt');
606: dt.textContent = name;
607: dialog.appendChild(dt);
608: var dd = document.createElement('dd');
609: dd.textContent = message;
610: dialog.appendChild(dd);
611: }
1.53 ihickson 612: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 613:
614: // PRIVATE CHAT
615: function startPrivateChat(event) {
1.54 ihickson 616: if (event.data.substr(0, 4) != 'msg ') return;
617: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 618: var port = event.ports[0];
1.36 ihickson 619: // display a private chat UI
620: var ul = document.getElementById('private');
621: var li = document.createElement('li');
622: var h3 = document.createElement('h3');
623: h3.textContent = 'Private chat with ' + name;
624: li.appendChild(h3);
625: var dialog = document.createElement('dialog');
626: var addMessage = function(name, message) {
627: var dt = document.createElement('dt');
628: dt.textContent = name;
629: dialog.appendChild(dt);
630: var dd = document.createElement('dd');
631: dd.textContent = message;
632: dialog.appendChild(dd);
633: };
634: port.onmessage = function (event) {
1.54 ihickson 635: addMessage(name, event.data);
1.36 ihickson 636: };
637: li.appendChild(dialog);
638: var form = document.createElement('form');
639: var p = document.createElement('p');
640: var input = document.createElement('input');
641: input.size = 50;
642: p.appendChild(input);
643: p.appendChild(document.createTextNode(' '));
644: var button = document.createElement('button');
645: button.textContent = 'Post';
646: p.appendChild(button);
647: form.onsubmit = function () {
648: port.postMessage(input.value);
649: addMessage('me', input.value);
650: input.value = '';
651: return false;
652: };
653: form.appendChild(p);
654: li.appendChild(form);
655: }
1.53 ihickson 656: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 657:
658: worker.port.start();
1.81 ihickson 659: </script>
660: </head>
661: <body>
662: <h1>Viewer</h1>
663: <h2>Map</h2>
664: <p><canvas id="map" height=150 width=150></canvas></p>
665: <p>
666: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
667: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
668: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
669: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
670: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
671: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
672: </p>
673: <h2>Public Chat</h2>
674: <dialog id="public"></dialog>
675: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
676: <p>
677: <input type="text" name="message" size="50">
678: <button>Post</button>
679: </p>
680: </form>
681: <h2>Private Chat</h2>
682: <ul id="private"></ul>
683: </body>
684: </html>
1.155 ihickson 685: </pre><p>There are several key things worth noting about the way the
686: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 687: processing function, the code here attaches multiple event
688: listeners, each one performing a quick check to see if it is
689: relevant for the message. In this example it doesn't make much
690: difference, but if multiple authors wanted to collaborate using a
691: single port to communicate with a worker, it would allow for
692: independent code instead of changes having to all be made to a
1.155 ihickson 693: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 694: unregister specific listeners when you are done with them, as is
695: done with the <code title="">configure()</code> method in this
1.155 ihickson 696: example.<p>Finally, the worker:<pre>
697: var nextName = 0;
1.36 ihickson 698: function getNextName() {
699: // this could use more friendly names
700: // but for now just return a number
701: return nextName++;
702: }
703:
704: var map = [
705: [0, 0, 0, 0, 0, 0, 0],
706: [1, 1, 0, 1, 0, 1, 1],
707: [0, 1, 0, 1, 0, 0, 0],
708: [0, 1, 0, 1, 0, 1, 1],
709: [0, 0, 0, 1, 0, 0, 0],
710: [1, 0, 0, 1, 1, 1, 1],
711: [1, 1, 0, 1, 1, 0, 1],
712: ];
713:
714: function wrapX(x) {
715: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 716: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 717: return x;
718: }
719:
720: function wrapY(y) {
721: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 722: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 723: return y;
724: }
725:
1.50 ihickson 726: function sendMapData(callback) {
1.36 ihickson 727: var data = '';
728: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
729: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
730: if (data != '')
731: data += ',';
732: data += map[y][x];
733: }
734: }
1.50 ihickson 735: callback('map ' + data);
1.36 ihickson 736: }
737:
738: var viewers = {};
739: onconnect = function (event) {
1.84 ihickson 740: event.ports[0]._name = getNextName();
741: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
742: viewers[event.ports[0]._name] = event.port._data;
743: event.ports[0].postMessage('cfg ' + name);
744: event.ports[0].onmessage = getMessage;
745: sendMapData(event.ports[0].postMessage);
1.36 ihickson 746: };
747:
748: function getMessage(event) {
1.54 ihickson 749: switch (event.data.substr(0, 4)) {
1.36 ihickson 750: case 'mov ':
1.54 ihickson 751: var direction = event.data.substr(4);
1.36 ihickson 752: var dx = 0;
753: var dy = 0;
754: switch (direction) {
755: case 'up': dy = -1; break;
756: case 'down': dy = 1; break;
757: case 'left': dx = -1; break;
758: case 'right': dx = 1; break;
759: }
760: event.target._data.x = wrapX(event.target._data.x + dx);
761: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 762: sendMapData(event.target.postMessage);
1.36 ihickson 763: break;
764: case 'set ':
1.54 ihickson 765: var value = event.data.substr(4);
1.36 ihickson 766: map[event.target._data.y][event.target._data.x] = value;
767: for (var viewer in viewers)
1.50 ihickson 768: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 769: break;
770: case 'txt ':
771: var name = event.target._name;
1.54 ihickson 772: var message = event.data.substr(4);
1.36 ihickson 773: for (var viewer in viewers)
774: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
775: break;
776: case 'msg ':
777: var party1 = event._data;
1.54 ihickson 778: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 779: if (party2) {
780: var channel = new MessageChannel();
1.84 ihickson 781: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
782: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 783: }
784: break;
785: }
1.155 ihickson 786: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 787: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 788: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 789: "msg" message from one viewer naming another viewer, it sets up a
790: direct connection between the two, so that the two viewers can
791: communicate directly without the worker having to proxy all the
1.238 ihickson 792: 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 793: performance is to split computationally expensive tasks amongst
794: multiple workers. In this example, a computationally expensive task
795: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 796: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 797: <html>
798: <head>
1.203 ihickson 799: <title>Worker example: Multicore computation</title>
1.81 ihickson 800: </head>
801: <body>
1.203 ihickson 802: <p>Result: <output id="result"></output></p>
1.81 ihickson 803: <script>
1.50 ihickson 804: var worker = new Worker('worker.js');
805: worker.onmessage = function (event) {
1.54 ihickson 806: document.getElementById('result').textContent = event.data;
1.40 ihickson 807: };
1.81 ihickson 808: </script>
809: </body>
1.155 ihickson 810: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 811: var num_workers = 10;
812: var items_per_worker = 1000000;
813:
814: // start the workers
815: var result = 0;
816: var pending_workers = num_workers;
817: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 818: var worker = new Worker('core.js');
819: worker.postMessage(i * items_per_worker);
820: worker.postMessage((i+1) * items_per_worker);
821: worker.onmessage = storeResult;
1.40 ihickson 822: }
823:
824: // handle the results
825: function storeResult(event) {
1.54 ihickson 826: result += 1*event.data;
1.40 ihickson 827: pending_workers -= 1;
828: if (pending_workers <= 0)
1.50 ihickson 829: postMessage(result); // finished!
1.155 ihickson 830: }</pre><p>It consists of a loop to start the subworkers, and then a handler
831: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 832: onmessage = getStart;
1.40 ihickson 833: function getStart(event) {
1.54 ihickson 834: start = 1*event.data;
1.40 ihickson 835: onmessage = getEnd;
836: }
837:
838: var end;
839: function getEnd(event) {
1.54 ihickson 840: end = 1*event.data;
1.40 ihickson 841: onmessage = null;
1.66 ihickson 842: work();
1.40 ihickson 843: }
844:
1.66 ihickson 845: function work() {
1.40 ihickson 846: var result = 0;
847: for (var i = start; i < end; i += 1) {
848: // perform some complex calculation here
849: result += 1;
850: }
1.50 ihickson 851: postMessage(result);
852: close();
1.155 ihickson 853: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 854: for the range of numbers thus specified, and then report the result
1.238 ihickson 855: 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 856: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 857:
858: <dd>Takes a port, on which it will send two messages, first the
859: public key and then the private key.</dd>
860:
861: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
862:
863: <dd>Takes a port, to which any number of messages can be sent, the
864: first giving the public key, and the remainder giving the
865: plaintext, each of which is encrypted and then sent on that same
866: channel as the cyphertext. The user can close the port when it is
867: done encrypting content.</dd>
868:
869: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
870:
871: <dd>Takes a port, to which any number of messages can be sent, the
872: first giving the private key, and the remainder giving the
873: cyphertext, each of which is decrypted and then sent on that same
874: channel as the plaintext. The user can close the port when it is
875: done decrypting content.</dd>
1.49 ihickson 876:
1.155 ihickson 877: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 878: if (e.data == "genkeys")
1.84 ihickson 879: genkeys(e.ports[0]);
1.54 ihickson 880: else if (e.data == "encrypt")
1.84 ihickson 881: encrypt(e.ports[0]);
1.54 ihickson 882: else if (e.data == "decrypt")
1.84 ihickson 883: decrypt(e.ports[0]);
1.49 ihickson 884: }
885:
886: function genkeys(p) {
887: var keys = _generateKeyPair();
888: p.postMessage(keys[0]);
889: p.postMessage(keys[1]);
890: }
891:
892: function encrypt(p) {
893: var key, state = 0;
894: p.onmessage = function (e) {
895: if (state == 0) {
1.54 ihickson 896: key = e.data;
1.49 ihickson 897: state = 1;
898: } else {
1.54 ihickson 899: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 900: }
901: };
902: }
903:
904: function decrypt(p) {
905: var key, state = 0;
906: p.onmessage = function (e) {
907: if (state == 0) {
1.54 ihickson 908: key = e.data;
1.49 ihickson 909: state = 1;
910: } else {
1.54 ihickson 911: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 912: }
913: };
914: }
915:
1.50 ihickson 916: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 917: if ('onmessage' in this) // dedicated worker
1.50 ihickson 918: onmessage = handleMessage;
919: else // shared worker
920: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 921:
922:
923: // the "crypto" functions:
924:
925: function _generateKeyPair() {
926: return [Math.random(), Math.random()];
927: }
928:
929: function _encrypt(k, s) {
930: return 'encrypted-' + k + ' ' + s;
931: }
932:
933: function _decrypt(k, s) {
934: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 935: }</pre><p>Note that the crypto functions here are just stubs and don't do
936: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 937: <html>
938: <head>
939: <title>Worker example: Crypto library</title>
940: <script>
1.50 ihickson 941: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 942: function getKeys() {
943: var state = 0;
1.50 ihickson 944: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 945: if (state == 0)
1.54 ihickson 946: document.getElementById('public').value = e.data;
1.49 ihickson 947: else if (state == 1)
1.54 ihickson 948: document.getElementById('private').value = e.data;
1.49 ihickson 949: state += 1;
950: };
951: }
952: function enc() {
1.50 ihickson 953: var port = cryptoLib.startConversation("encrypt");
954: port.postMessage(document.getElementById('public').value);
955: port.postMessage(document.getElementById('input').value);
956: port.onmessage = function (e) {
1.54 ihickson 957: document.getElementById('input').value = e.data;
1.50 ihickson 958: port.close();
1.49 ihickson 959: };
960: }
961: function dec() {
1.50 ihickson 962: var port = cryptoLib.startConversation("decrypt");
963: port.postMessage(document.getElementById('private').value);
964: port.postMessage(document.getElementById('input').value);
965: port.onmessage = function (e) {
1.54 ihickson 966: document.getElementById('input').value = e.data;
1.50 ihickson 967: port.close();
1.49 ihickson 968: };
969: }
1.81 ihickson 970: </script>
971: <style>
1.49 ihickson 972: textarea { display: block; }
1.81 ihickson 973: </style>
974: </head>
975: <body onload="getKeys()">
976: <fieldset>
977: <legend>Keys</legend>
978: <p><label>Public Key: <textarea id="public"></textarea></label></p>
979: <p><label>Private Key: <textarea id="private"></textarea></label></p>
980: </fieldset>
981: <p><label>Input: <textarea id="input"></textarea></label></p>
982: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
983: </body>
1.155 ihickson 984: </html></pre><p>A later version of the API, though, might want to offload all the
985: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 986: if (e.data == "genkeys")
1.84 ihickson 987: genkeys(e.ports[0]);
1.54 ihickson 988: else if (e.data == "encrypt")
1.84 ihickson 989: encrypt(e.ports[0]);
1.54 ihickson 990: else if (e.data == "decrypt")
1.84 ihickson 991: decrypt(e.ports[0]);
1.49 ihickson 992: }
993:
994: function genkeys(p) {
1.50 ihickson 995: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 996: generator.postMessage('', [p]);
1.49 ihickson 997: }
998:
999: function encrypt(p) {
1000: p.onmessage = function (e) {
1.54 ihickson 1001: var key = e.data;
1.50 ihickson 1002: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 1003: encryptor.postMessage(key, [p]);
1.49 ihickson 1004: };
1005: }
1006:
1007: function encrypt(p) {
1008: p.onmessage = function (e) {
1.54 ihickson 1009: var key = e.data;
1.50 ihickson 1010: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 1011: decryptor.postMessage(key, [p]);
1.49 ihickson 1012: };
1013: }
1014:
1.50 ihickson 1015: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 1016: if ('onmessage' in this) // dedicated worker
1.50 ihickson 1017: onmessage = handleMessage;
1018: else // shared worker
1.84 ihickson 1019: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 1020: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 1021: var k = _generateKeyPair();
1.84 ihickson 1022: e.ports[0].postMessage(k[0]);
1023: e.ports[0].postMessage(k[1]);
1.49 ihickson 1024: close();
1025: }
1.50 ihickson 1026:
1027: function _generateKeyPair() {
1028: return [Math.random(), Math.random()];
1.155 ihickson 1029: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 1030: var key = e.data;
1.84 ihickson 1031: e.ports[0].onmessage = function (e) {
1.54 ihickson 1032: var s = e.data;
1.50 ihickson 1033: postMessage(_encrypt(key, s));
1.49 ihickson 1034: }
1.50 ihickson 1035: }
1036:
1037: function _encrypt(k, s) {
1038: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 1039: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 1040: var key = e.data;
1.84 ihickson 1041: e.ports[0].onmessage = function (e) {
1.54 ihickson 1042: var s = e.data;
1.50 ihickson 1043: postMessage(_decrypt(key, s));
1.49 ihickson 1044: }
1.50 ihickson 1045: }
1046:
1047: function _decrypt(k, s) {
1048: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 1049: }</pre><p>Notice how the users of the API don't have to even know that this
1050: is happening — the API hasn't changed; the library can
1.81 ihickson 1051: delegate to subworkers without changing its API, even though it is
1.155 ihickson 1052: 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 1053: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 1054: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 1055: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
1056: "OPTIONAL" in the normative parts of this document are to be
1057: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 1058: 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 1059: (such as "strip any leading space characters" or "return false and
1060: abort these steps") are to be interpreted with the meaning of the
1061: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 1062: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 1063: attributes, methods or objects. Such requirements are to be
1.155 ihickson 1064: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 1065: may be implemented in any manner, so long as the end result is
1066: equivalent. (In particular, the algorithms defined in this
1067: specification are intended to be easy to follow, and not intended to
1.155 ihickson 1068: be performant.)<p>The only conformance class defined by this specification is user
1069: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 1070: otherwise unconstrained inputs, e.g. to prevent denial of service
1071: attacks, to guard against running out of memory, or to work around
1.229 ihickson 1072: platform-specific limitations.<p>When support for a feature is disabled (e.g. as an emergency
1073: measure to mitigate a security problem, or to aid in development, or
1074: for performance reasons), user agents must act as if they had no
1075: support for the feature whatsoever, and as if the feature was not
1076: mentioned in this specification. For example, if a particular
1077: feature is accessed via an attribute in a Web IDL interface, the
1078: attribute itself would be omitted from the objects that implement
1079: that interface — leaving the attribute on the object but
1080: 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 1081: specifications.<dl><dt>HTML</dt>
1.49 ihickson 1082:
1.81 ihickson 1083: <dd>
1.49 ihickson 1084:
1.226 ihickson 1085: <p>Many fundamental concepts from HTML are used by this
1086: specification. <a href="#refsHTML">[HTML]</a></p>
1.49 ihickson 1087:
1.81 ihickson 1088: </dd>
1.1 ihickson 1089:
1.81 ihickson 1090: <dt>WebIDL</dt>
1.1 ihickson 1091:
1092: <dd>
1093:
1.81 ihickson 1094: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 1095: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 1096:
1.81 ihickson 1097: </dd>
1.1 ihickson 1098:
1.155 ihickson 1099: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 1100: <code title="">Foo</code> is actually an interface, is sometimes
1101: used instead of the more accurate "an object implementing the
1.155 ihickson 1102: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1103: scripts in Web applications, and does not necessarily imply the
1104: existence of an actual <code>Document</code> object or of any other
1105: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 1106: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1107: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1108: <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 1109: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1110: 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 1111: workers. Dedicated workers, once created, and are linked to their
1112: creator; but message ports can be used to communicate from a
1113: dedicated worker to multiple other browsing contexts or
1114: workers. Shared workers, on the other hand, are named, and once
1115: created any script running in the same <span>origin</span> can
1.155 ihickson 1116: 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 1117: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1118: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1119:
1120: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1121: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1122: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1123: };
1.172 ihickson 1124: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
1125: <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 1126: 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 1127: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1128: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1129: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1130: 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 1131: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1132: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1133: have been added to the <span>event loop</span>'s <span title="task
1134: queue">task queues</span>.</p>
1135:
1136: <!-- v2-onclose
1137: <li><p><span>Queue a task</span> to <span>fire a simple
1.179 ihickson 1138: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1139: <code>WorkerGlobalScope</code> object.</p></li>
1140: -->
1.81 ihickson 1141:
1.115 ihickson 1142: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1143: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1144: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1145:
1.177 ihickson 1146: </ol><p>The following are the <span>event handlers</span> (and their
1147: corresponding <span title="event handler event type">event handler
1148: event types</span>) that must be supported, as IDL attributes, by
1149: objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1150: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1151: <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 1152: </table><hr><p>The <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface must not exist if
1153: the interface's <span>relevant namespace object</span> is a
1154: <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 1155: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.174 ihickson 1156: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.77 ihickson 1157: <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1158: attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1159: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1160: had an implicit <code>MessagePort</code> associated with them. This
1161: port is part of a channel that is set up when the worker is created,
1162: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1163: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1164: 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 1165: and <dfn
1166: title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
1.81 ihickson 1167: method<!--s (startConversation)--> on
1.115 ihickson 1168: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.81 ihickson 1169: invoked, it<!--/they (startConversation)--> immediately invoked the
1170: method of the same name on the port, with the same arguments, and
1.177 ihickson 1171: returned the same return value.<p>The following are the <span>event handlers</span> (and their
1172: corresponding <span title="event handler event type">event handler
1173: event types</span>) that must be supported, as IDL attributes, by
1174: objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1175: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1176: <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 1177: </table><p>For the purposes of the <span>application cache</span> networking
1178: model, a dedicated worker is an extension of the <span>cache
1179: host</span> from which it was created.<h4 id="shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> inteface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1180: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1181: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1182: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.144 ihickson 1183: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1184: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1185: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1186: attribute must return the value it was assigned when the
1.115 ihickson 1187: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1188: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1189: that can be used to obtain a reference to the worker using the
1.177 ihickson 1190: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handlers</span> (and their
1191: corresponding <span title="event handler event type">event handler
1192: event types</span>) that must be supported, as IDL attributes, by
1193: objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1194: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1195: <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 1196: </table><p>For the purposes of the <span>application cache</span> networking
1197: model, a shared worker is its own <span>cache host</span>. The
1198: <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1199: worker with an <span>application cache</span>.<p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
1.123 ihickson 1200: attribute returns the <code>ApplicationCache</code> object for the
1.101 ihickson 1201: worker.</p><!-- normative conf criteria is in the appcache section
1.160 ihickson 1202: --><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 1203: origin</span> of scripts running in workers are the
1204: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1205: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.186 ihickson 1206: 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 1207: loop</span> distinct from those defined for <span title="unit of
1208: related similar-origin browsing contexts">units of related
1209: similar-origin browsing contexts</span>. This <span>event
1210: loop</span> has no associated <span>browsing context</span>, and its
1211: <span title="task queue">task queues</span> only have events,
1212: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1213: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1214: <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 1215: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1216: 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 1217: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1218: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1219: already on the queue are unaffected except where otherwise
1.115 ihickson 1220: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1221: timers stop firing, notifications for all pending asynchronous
1.186 ihickson 1222: 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 1223: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1224: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1225: consists of all the <code>MessagePort</code> objects that are
1226: entangled with another port and that have one (but only one) port
1227: owned by <var title="">worker global scope</var>. This list includes
1228: <!--all the <code>MessagePort</code> objects that are in events
1.68 ihickson 1229: pending in the <span>event loop</span>, as well as (commented out
1230: because in practice it makes no difference either way as far as I
1231: can tell, and it would be hard to strictly implement since these
1.81 ihickson 1232: ports might not yet be across the thread boundary)--> the implicit
1.155 ihickson 1233: <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 1234: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1235: 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 1236: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1237: 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 1238: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1239: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1240: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1241: <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 1242: documents">add <var title="">d</var> to <var title="">q</var>'s
1243: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.155 ihickson 1244: <code>Document</code>s</span></a>.</p><!-- suggestions welcome
1245: on making this sentence into understandable English --><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1246: Document">discarded</span>, it must be removed from the list of
1247: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.192 ihickson 1248: whose list contains that <code>Document</code>.<p>Given a <span>script's global object</span> <var title="">o</var>
1.123 ihickson 1249: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1250: <code>Document</code> objects to add</dfn> depends on the type of
1251: <var title="">o</var>. If <var title="">o</var> is a
1252: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1253: nested worker), then the relevant <code>Document</code>s are the
1254: <code>Document</code>s that are in <var title="">o</var>'s own list
1255: 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
1256: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1257: <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 1258: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1259: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1260: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1261: timers, database transactions, or network connections, or its list
1.124 ihickson 1262: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1263: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1264: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1265: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1266: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1267: <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 1268: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.186 ihickson 1269: <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 1270: <span>URL</span> <var title="">url</var>, a <span>browsing
1271: context</span> <var title="">owner browsing context</var>, a
1272: <code>Document</code> <var title="">owner document</var>, an
1273: <span>origin</span> <var title="">owner origin</var>, and with
1274: global scope <var title="">worker global scope</var>, it must run
1275: the following steps:<ol><li>
1.81 ihickson 1276:
1277: <p>Create a completely separate and parallel execution environment
1278: (i.e. a separate thread or process or equivalent construct), and
1.106 ihickson 1279: run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1280:
1281: </li>
1.4 ihickson 1282:
1.101 ihickson 1283: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1284: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1285: shared worker), and there are any <span title="relevant application
1286: cache">relevant application caches</span> that are identified by a
1287: 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 1288: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1289: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1290: cache</span> of those that match.</li>
1291:
1.4 ihickson 1292: <li>
1.52 ihickson 1293:
1.256 ihickson 1294: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>,
1295: with the <i>synchronous flag</i> set and the <i>force same-origin
1296: flag</i> set.</p> <!-- not http-origin privacy sensitive (looking
1297: forward to CORS) -->
1298:
1299: <p>If the attempt fails, then for each <code><a href="#worker">Worker</a></code> or
1300: <code><a href="#sharedworker">SharedWorker</a></code> object associated with <var title="">worker global scope</var>, <span>queue a task</span> to
1301: <span>fire a simple event</span> named <code title="event-error">error</code> at that object. Abort these
1302: steps.</p>
1.7 ihickson 1303:
1.186 ihickson 1304: <p>If the attempt succeeds, then convert the script resource to
1305: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.81 ihickson 1306:
1.68 ihickson 1307: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1308:
1.115 ihickson 1309: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1310: type of the script is ignored. Unlike with <code>script</code>
1311: elements, there is no way to override the type. It's always
1.170 ihickson 1312: assumed to be JavaScript.</p>
1.81 ihickson 1313:
1314: </li>
1.7 ihickson 1315:
1316: <li>
1.68 ihickson 1317:
1.115 ihickson 1318: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1319: created, as follows.</p>
1320:
1321: <p>Create a new <span>script execution environment</span>
1322: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1323:
1.68 ihickson 1324: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1325: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1326: entry-points</span>; set the <i>initial code entry-point</i> to
1327: the entry-point for any executable code to be immediately run.</p>
1328:
1329: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1330:
1331: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1332:
1.232 ihickson 1333: <p>Set the <span>script's document</span> to <var title="">owner
1334: document</var>.</p>
1335:
1.83 ihickson 1336: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1337: UTF-8. (This is just used for encoding non-ASCII characters in the
1338: query component of URLs.)</p>
1.68 ihickson 1339:
1340: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1341:
1.81 ihickson 1342: </li>
1.4 ihickson 1343:
1344: <li>
1.81 ihickson 1345:
1346: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1347: worker such that no sooner than it stops being either a
1348: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1349: worker</a>, and no later than it stops being a
1350: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1351: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1352: to true<!-- v2-onclose and <span title="queue a task">a task is
1.179 ihickson 1353: queued</span> to <span>fire a simple event</span> named <code
1.123 ihickson 1354: title="event-close">close</code> at <var title="">worker global
1355: scope</var>-->.</p>
1.81 ihickson 1356:
1357: </li>
1.9 ihickson 1358:
1359: <li>
1.7 ihickson 1360:
1.81 ihickson 1361: <p><strong>Suspending workers</strong>: Start monitoring the
1362: worker, such that whenever <var title="">worker global
1.115 ihickson 1363: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1364: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1365: agent suspends execution of script in that worker until such time
1.115 ihickson 1366: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1367: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1368: worker</a>.</p>
1.4 ihickson 1369:
1.81 ihickson 1370: </li>
1.68 ihickson 1371:
1372: <li>
1.4 ihickson 1373:
1.81 ihickson 1374: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1375: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1376: entry-point</i>, and let that run until it either returns, fails
1377: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1378: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1379: algorithms defined below.</p>
1380:
1.149 ihickson 1381: <!-- v2-onclose
1382: <p class="note">If the script gets aborted by the "<span>kill a
1383: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1384: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1385: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1386: for the <code title="message-close">close</code> event. The
1.149 ihickson 1387: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1388: events.</p>
1.149 ihickson 1389: -->
1.4 ihickson 1390:
1.81 ihickson 1391: </li>
1.4 ihickson 1392:
1.95 ihickson 1393: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1394: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1395: a dedicated worker), then enable the <span>port message
1396: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1397:
1.4 ihickson 1398: <li>
1.68 ihickson 1399:
1.115 ihickson 1400: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1401: 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 1402: to true.</p>
1.43 ihickson 1403:
1.81 ihickson 1404: </li>
1.4 ihickson 1405:
1406: <li>
1407:
1.81 ihickson 1408: <p>Run the oldest task on one of the <span>event loop</span>'s
1409: <span title="task queue">task queues</span>, if any. The user
1410: agent may pick any <span>task queue</span>.</p>
1411:
1.115 ihickson 1412: <p class="note">The handling of events or the execution of
1413: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1414: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1415: defined below.</p>
1.8 ihickson 1416:
1.81 ihickson 1417: </li>
1.4 ihickson 1418:
1419: <li>
1420:
1.248 ihickson 1421: <p>If the <span>storage mutex</span> is now owned by the worker's
1422: <span>event loop</span>, release it so that it is once again
1423: free.</p>
1424:
1425: </li>
1426:
1427: <li>
1428:
1429: <p>Remove the task just run in the earlier step, if any, from its
1.81 ihickson 1430: <span>task queue</span>.</p>
1.4 ihickson 1431:
1.81 ihickson 1432: </li>
1.4 ihickson 1433:
1434: <li>
1.8 ihickson 1435:
1.81 ihickson 1436: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1437: <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 1438: to false, then jump back to the step above labeled <i>event
1439: loop</i>.</p>
1.8 ihickson 1440:
1.81 ihickson 1441: </li>
1.8 ihickson 1442:
1443: <li>
1.71 ihickson 1444:
1.123 ihickson 1445: <p>If there are any outstanding transactions that have callbacks
1446: that involve <span title="concept-script">scripts</span> whose
1447: <span title="script's global object">global object</span> is the
1448: <var title="">worker global scope</var>, roll them back (without
1.258 ihickson 1449: invoking any of the callbacks). <a href="#refsWEBSQL">[WEBSQL]</a></p>
1.50 ihickson 1450:
1.123 ihickson 1451: </li>
1452:
1453: <li>
1454:
1455: <p>Empty the <var title="">worker global scope</var>'s <span>list
1456: of active timeouts</span> and its <span>list of active
1457: intervals</span>.</p>
1.50 ihickson 1458:
1.81 ihickson 1459: </li>
1.50 ihickson 1460:
1.247 ihickson 1461: <li>
1462:
1463: <p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1464: ports</a>.</p>
1465:
1466: </li>
1467:
1.123 ihickson 1468: <!-- v2-onclose
1.81 ihickson 1469: <li>
1.50 ihickson 1470:
1.123 ihickson 1471: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1472: object associated with <var title="">worker global scope</var>,
1473: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1474: named <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1475:
1.81 ihickson 1476: </li>
1.123 ihickson 1477: -->
1.155 ihickson 1478: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1479: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1480: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1481: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1482: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1483: false, <span>queue a task</span> to <span>fire a simple
1.179 ihickson 1484: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1485: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1486: --><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 1487: true.</li>
1488:
1.123 ihickson 1489: <!-- v2-onclose
1490: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1491: a worker</span>" processing model defined above immediately starts
1492: running event listeners registered for the <code
1493: title="event-close">close</code> event, this time should not be
1494: zero — the idea is that the <code
1495: title="event-close">close</code> event can be used to clean up
1496: when shutting down unexpectedly.</p></li>
1497: -->
1.81 ihickson 1498:
1.115 ihickson 1499: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1500: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1501: queue">task queues</span><!-- v2-onclose other than the <code
1502: title="event-close">close</code> event that this algorithm just
1503: added-->, discard them without processing them.</li>
1.81 ihickson 1504:
1.123 ihickson 1505: <!-- v2-onclose
1.115 ihickson 1506: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1507: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1508: the script currently running in the worker.</p></li>
1509: -->
1.81 ihickson 1510:
1511: <li><p>Wait a user-agent-defined amount of time.</li>
1512:
1.123 ihickson 1513: <li><p>Abort the script currently running in the worker<!--
1514: v2-onclose (if any script is running, then it will be a handler for
1515: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1516:
1.155 ihickson 1517: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1518: processing model on a worker at any time, e.g. in response to user
1519: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1520: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1521: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1522: 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 1523: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1524: "<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 1525: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1526: true.</li>
1527:
1.115 ihickson 1528: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1529: queued in the <span>event loop</span>'s <span title="task
1530: queue">task queues</span>, discard them without processing
1531: them.</li>
1532:
1533: <li><p>Abort the script currently running in the worker.</li>
1534:
1.115 ihickson 1535: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1536: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1537: worker is a dedicated worker), then empty the <span>port message
1538: queue</span> of the port that the worker's implicit port is
1539: entangled with.</li>
1540:
1.155 ihickson 1541: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.186 ihickson 1542: <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 1543: worker's scripts, if the error did not occur while handling a
1544: previous script error, the user agent must <span>report the
1545: 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 1546: attribute.
1547:
1.226 ihickson 1548: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1549:
1550: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1551: the error occurred while handling a previous script error, the error
1.215 ihickson 1552: may be reported to the user.
1.205 ihickson 1553:
1.226 ihickson 1554: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1555:
1556: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1557: the error occurred while handling a previous script error, the user
1.123 ihickson 1558: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1559: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1560: 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 1561: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1562: 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 1563: 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 1564: appropriately. The default action of this event depends on whether
1.115 ihickson 1565: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1566: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1567: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1568: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1.215 ihickson 1569: <em>that</em> worker. Otherwise, then the error may be reported
1.155 ihickson 1570: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1.233 ihickson 1571: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : <span>Event</span> {
1.147 ihickson 1572: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1573: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1574: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1575: 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 1576: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.190 ihickson 1577: method must initialize the event in a manner analogous to the
1578: 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 1579: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1580: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1581: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1582: attribute represents the line number where the error occurred in the
1.208 ihickson 1583: 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]
1584: interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1585: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1586: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.172 ihickson 1587: };
1.177 ihickson 1588: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handlers</span> (and their
1589: corresponding <span title="event handler event type">event handler
1590: event types</span>) that must be supported, as IDL attributes, by
1591: 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 1592: <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 1593: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.186 ihickson 1594: </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 1595: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1596: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1597:
1.174 ihickson 1598: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1599: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1600: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1601: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1602: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1603: algorithm to be run on the worker with with the object is
1.155 ihickson 1604: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1605: <code>MessagePort</code> associated with them. This port is part of
1606: a channel that is set up when the worker is created, but it is not
1607: exposed. This object must never be garbage collected before the
1.155 ihickson 1608: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1609: 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 1610: and <dfn
1611: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1612: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1613: must act as if, when invoked, it<!--/they (startConversation)-->
1614: immediately invoked the method of the same name on the port, with
1.177 ihickson 1615: the same arguments, and returned the same return value.<p>The following are the <span>event handlers</span> (and their
1616: corresponding <span title="event handler event type">event handler
1617: event types</span>) that must be supported, as IDL attributes, by
1618: 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 1619: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1620: </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 1621: 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 1622: script</span>'s <span title="script's base URL">base URL</span>,
1623: when the method is invoked.</li>
1.9 ihickson 1624:
1.81 ihickson 1625: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1626: exception.</li>
1.9 ihickson 1627:
1.167 ihickson 1628: <li>
1629:
1630: <p>If the <span>origin</span> of the resulting <span>absolute
1631: URL</span> is not the <span title="same origin">same</span> as the
1.216 ihickson 1632: origin of the <span>entry script</span>, then throw a
1.182 ihickson 1633: <code>SECURITY_ERR</code> exception.</p>
1.167 ihickson 1634:
1635: <p class="note">Thus, scripts must be external files with the same
1636: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1637: URL, and a <code>http:</code> page couldn't start workers using
1638: scripts with <code>http:</code> URLs.</p>
1639:
1640: </li>
1.9 ihickson 1641:
1.185 ihickson 1642: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1643: object. Let <var title="">worker global scope</var> be this new
1644: object.</li>
1.9 ihickson 1645:
1.115 ihickson 1646: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1647: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1648:
1.185 ihickson 1649: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1650: owned by the <span title="script's global object">global
1651: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1652: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1653: port</var>.</li>
1.9 ihickson 1654:
1.81 ihickson 1655: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1656:
1.185 ihickson 1657: <li><p><span>Create a new <code>MessagePort</code> object</span>
1658: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1659:
1.81 ihickson 1660: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1661:
1.81 ihickson 1662: <li><p><span>Entangle</span> <var title="">outside port</var> and
1663: <var title="">inside port</var>.</li>
1.50 ihickson 1664:
1.81 ihickson 1665: <li><p>Return <var title="">worker</var>, and run the following
1666: steps asynchronously.</li>
1.50 ihickson 1667:
1.204 ihickson 1668: <!-- (this is done by the "run a worker" algorithm)
1.126 ihickson 1669: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.204 ihickson 1670: queue</span>.</p></li>
1671: -->
1.50 ihickson 1672:
1.126 ihickson 1673: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1674: queue</span>.</li>
1.50 ihickson 1675:
1676: <li>
1.51 ihickson 1677:
1.123 ihickson 1678: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1679: <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 1680: constructor.</p>
1681:
1682: </li>
1683:
1684: <li>
1685:
1686: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1687: <var title="">worker global scope</var>'s list of <span>the
1688: worker's <code>Document</code>s</span></a> the
1689: <code>Document</code> objects in <var title="">docs</var>.</p>
1690:
1691: </li>
1692:
1693: <li>
1694:
1.192 ihickson 1695: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1696: of the <span title="concept-script">script</span> that invoked the
1697: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1698: are creating a nested worker), add <var title="">worker global
1699: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 1700: <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 1701: constructor.</p>
1702:
1703: </li>
1704:
1705: <li>
1706:
1.115 ihickson 1707: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 1708: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 1709: script that invoked the method as the <var title="">owner browsing
1.232 ihickson 1710: context</var>, with the <span>script's document</span> of the
1711: script that invoked the method as the <var title="">owner
1712: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1713: script</span> as the <var title="">owner origin</var>, and with
1714: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1715:
1.81 ihickson 1716: </li>
1.4 ihickson 1717:
1.155 ihickson 1718: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1719: object</span> is either a <code>Window</code> object or an object
1.186 ihickson 1720: 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 1721: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1722: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1723: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1724: attribute must return the value it was assigned by the object's
1725: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1726: 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 1727: constructor is invoked, the user agent must run the following
1.155 ihickson 1728: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1729:
1730: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1731: exception.</li>
1732:
1.159 ihickson 1733: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1734: resulting <span>absolute URL</span>.</li>
1735:
1736: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1737: argument, or the empty string if the second argument was
1738: omitted.</li>
1.159 ihickson 1739:
1.167 ihickson 1740: <li>
1741:
1742: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1743: not the <span title="same origin">same</span> as the origin of the
1.216 ihickson 1744: <span>entry script</span>, then throw a <code>SECURITY_ERR</code>
1.182 ihickson 1745: exception.</p>
1.167 ihickson 1746:
1747: <p class="note">Thus, scripts must be external files with the same
1748: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1749: URL, and a <code>http:</code> page couldn't start workers using
1750: scripts with <code>http:</code> URLs.</p>
1751:
1752: </li>
1.9 ihickson 1753:
1754: <li>
1755:
1.123 ihickson 1756: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1757: <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 1758: constructor.</p>
1759:
1760: </li>
1761:
1762: <li>
1763:
1.50 ihickson 1764: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1765:
1.155 ihickson 1766: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1767: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1768: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1769:
1.185 ihickson 1770: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1771: owned by the <span title="script's global object">global
1772: object</span> of the script that invoked the method. Let this be
1.123 ihickson 1773: the <var title="">outside port</var>.</li>
1.81 ihickson 1774:
1.115 ihickson 1775: <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 1776:
1.164 ihickson 1777: <li><p>Let <var title="">worker global scope</var> be
1778: null.</li>
1779:
1780: <li><p>If <var title="">name</var> is not the empty string and
1781: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1782: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1783: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1784: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1785: represents an <span>absolute URL</span> with the <span>same
1786: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1787: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1788:
1789: <li><p>Otherwise, if <var title="">name</var> is the empty string
1790: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1791: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1792: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.237 ihickson 1793: represents an <span>absolute URL</span> that is exactly equal to
1794: <var title="">scriptURL</var>, then let <var title="">worker
1795: global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1796: object.</li>
1.164 ihickson 1797:
1.9 ihickson 1798: <li>
1799:
1.164 ihickson 1800: <p>If <var title="">worker global scope</var> is not null, then
1801: run these steps:</p>
1.81 ihickson 1802:
1.164 ihickson 1803: <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 1804: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1805: exactly equal to <var title="">scriptURL</var>, then throw a
1806: <code>URL_MISMATCH_ERR</code> exception and abort all these
1807: steps.</li>
1.81 ihickson 1808:
1809: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1810:
1.185 ihickson 1811: <li><p><span>Create a new <code>MessagePort</code>
1812: object</span> owned by <var title="">worker global
1813: scope</var>. Let this be the <var title="">inside
1814: port</var>.</li>
1.81 ihickson 1815:
1816: <li><p><span>Entangle</span> <var title="">outside port</var>
1817: and <var title="">inside port</var>.</li>
1818:
1819: <li><p>Return <var title="">worker</var> and perform the next
1820: step asynchronously.</li>
1.9 ihickson 1821:
1.81 ihickson 1822: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1823: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1824: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1825: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1826: value is an array containing only the newly created port, and
1827: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1828:
1.123 ihickson 1829: <li>
1830:
1831: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1832: <var title="">worker global scope</var>'s list of <span>the
1833: worker's <code>Document</code>s</span></a> the
1834: <code>Document</code> objects in <var title="">docs</var>.</p>
1835:
1836: </li>
1837:
1.124 ihickson 1838: <li>
1839:
1.192 ihickson 1840: <p>If the <span title="script's global object">global
1841: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1842: that invoked the constructor is a
1843: <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
1844: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1845: object that is the <span title="script's global object">global
1846: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1847: that invoked the constructor.</p>
1848:
1849: </li>
1850:
1.81 ihickson 1851: <li><p>Abort all these steps.</li>
1.9 ihickson 1852:
1.155 ihickson 1853: </ol></li>
1.9 ihickson 1854:
1.185 ihickson 1855: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1856: object. Let <var title="">worker global scope</var> be this new
1857: object.</li>
1.9 ihickson 1858:
1.81 ihickson 1859: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1860:
1.115 ihickson 1861: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1862: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1863:
1.185 ihickson 1864: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.81 ihickson 1865: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1866:
1.81 ihickson 1867: <li><p><span>Entangle</span> <var title="">outside port</var> and
1868: <var title="">inside port</var>.</li>
1.9 ihickson 1869:
1.155 ihickson 1870: </ol></li>
1.28 ihickson 1871:
1.123 ihickson 1872: <li><p>Return <var title="">worker</var> and perform the remaining
1873: steps asynchronously.</li>
1.18 ihickson 1874:
1.81 ihickson 1875: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1876: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1877: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1878: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1879: is an array containing only the newly created port, and <span>queue
1880: a task</span> to dispatch the event at <var title="">worker global
1881: scope</var>.</li>
1.26 ihickson 1882:
1883: <li>
1.46 ihickson 1884:
1.123 ihickson 1885: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1886: <var title="">worker global scope</var>'s list of <span>the
1887: worker's <code>Document</code>s</span></a> the
1888: <code>Document</code> objects in <var title="">docs</var>.</p>
1889:
1890: </li>
1891:
1892: <li>
1893:
1.192 ihickson 1894: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1895: of the <span title="concept-script">script</span> that invoked the
1896: 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
1897: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1898: object that is the <span title="script's global object">global
1899: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1900: that invoked the constructor.</p>
1901:
1902: </li>
1903:
1904: <li>
1905:
1.159 ihickson 1906: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 1907: with the <span>script's browsing context</span> of the script that
1.159 ihickson 1908: invoked the method as the <var title="">owner browsing
1.232 ihickson 1909: context</var>, with the <span>script's document</span> of the
1910: script that invoked the method as the <var title="">owner
1911: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 1912: script</span> as the <var title="">owner origin</var>, and with
1913: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1914:
1.60 ihickson 1915: </li>
1.81 ihickson 1916:
1.155 ihickson 1917: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1918: object</span> is either a <code>Window</code> object or an object
1.155 ihickson 1919: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1920: <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 1921: interface <dfn id="workerutils">WorkerUtils</dfn> {
1922: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.210 ihickson 1923: readonly attribute <a href="#workernavigator">WorkerNavigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 1924: };
1.184 ihickson 1925: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1926: objects, etc) are not available to workers in this version of this
1.155 ihickson 1927: 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 1928: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1929: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1930: anything. Abort these steps.</li>
1931:
1932: <li><p><span title="resolve a url">Resolve</span> each
1933: argument.</li>
1934:
1935: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1936: exception.</li>
1937:
1938: <!--
1.67 ihickson 1939: <li><p>If any of the resulting <span title="absolute URL">absolute
1940: URLs</span> have an <span>origin</span> that is not the <span
1941: title="same origin">same</span> as the origin of the script that
1.182 ihickson 1942: invoked the method, then throw a <code>SECURITY_ERR</code>
1943: exception.</p></li>
1.67 ihickson 1944: -->
1.26 ihickson 1945:
1946: <li>
1.81 ihickson 1947:
1.45 ihickson 1948: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 1949: resulting <span title="absolute URL">absolute URLs</span>, from
1.256 ihickson 1950: the <span>entry script</span>'s <span>origin</span>, with the
1951: <i>synchronous flag</i> set.</p> <!-- not http-origin privacy
1952: sensitive -->
1.81 ihickson 1953:
1954: </li>
1.26 ihickson 1955:
1956: <li>
1957:
1.81 ihickson 1958: <p>For each argument in turn, in the order given, starting with
1959: the first one, run these substeps:</p>
1.26 ihickson 1960:
1.155 ihickson 1961: <ol><li>
1.26 ihickson 1962:
1.81 ihickson 1963: <p>Wait for the fetching attempt for the corresponding resource
1964: to complete.</p>
1.60 ihickson 1965:
1.81 ihickson 1966: <p>If the fetching attempt failed, throw a
1967: <code>NETWORK_ERR</code> exception and abort all these
1968: steps.</p>
1.45 ihickson 1969:
1.186 ihickson 1970: <p>If the attempt succeeds, then convert the script resource to
1971: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.85 ihickson 1972:
1973: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1974:
1.115 ihickson 1975: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1976: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1977: type.</p>
1.61 ihickson 1978:
1.81 ihickson 1979: </li>
1.26 ihickson 1980:
1.81 ihickson 1981: <li>
1.26 ihickson 1982:
1.81 ihickson 1983: <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 1984: same global object, browsing context, URL character encoding,
1985: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 1986: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1987:
1.115 ihickson 1988: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1989: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1990: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1991: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1992:
1.199 ihickson 1993: <p>If it failed to parse, then throw an ECMAScript
1994: <code>SyntaxError</code> exception and abort all these
1995: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 1996:
1.81 ihickson 1997: <p>If an exception was raised or if the script was prematurely
1998: aborted, then abort all these steps, letting the exception or
1999: aborting continue to be processed by the script that called the
1.115 ihickson 2000: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 2001: method.</p>
2002:
1.115 ihickson 2003: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 2004: worker</a>" algorithms abort the script then abort all these
2005: steps.</p>
2006:
2007: </li>
2008:
1.155 ihickson 2009: </ol></li>
1.152 ihickson 2010:
1.210 ihickson 2011: </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 2012: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1.210 ihickson 2013: the <code><a href="#workernavigator">WorkerNavigator</a></code> interface, which represents the
2014: identity and state of the user agent (the client):<pre class="idl">interface <dfn id="workernavigator">WorkerNavigator</dfn> {};
2015: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorID</span>;
2016: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorOnLine</span>;</pre><p>Objects implementing the <code><a href="#workernavigator">WorkerNavigator</a></code> interface
2017: also implement the <code>NavigatorID</code> and
2018: <code>NavigatorOnLine</code> interfaces.
1.205 ihickson 2019:
1.226 ihickson 2020: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2021:
1.210 ihickson 2022: <p>This <code><a href="#workernavigator">WorkerNavigator</a></code> interface must not exist if the
2023: interface's <span>relevant namespace object</span> is a
2024: <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 2025: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.200 ihickson 2026: 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 2027: the global scope of scripts whose <span>script's global
2028: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 2029: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 2030: constructors defined by the XMLHttpRequest specifications, except
2031: that the <span>document response entity body</span> must always be
1.160 ihickson 2032: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
2033: <span>script's base URL</span>; the
2034: <span><code>XMLHttpRequest</code> origin</span> is the script's
2035: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 2036:
1.205 ihickson 2037: <li><p>The interface objects and constructors defined by this
2038: specification.</li>
1.119 ihickson 2039:
1.205 ihickson 2040: <li><p>Constructors defined by specifications that explicitly say
2041: that they should be visible when the <span>script's global
2042: object</span> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>, a
2043: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>, or an object implementing the
2044: <code><a href="#workerutils">WorkerUtils</a></code> interface; the interfaces of any objects
2045: with such constructors; and the interfaces of any objects made
2046: accessible through APIs exposed by those constructors or made
2047: accessible through interfaces to be implemented by any objects that
2048: are themselves accessible to scripts whose <span>script's global
2049: object</span> implements the <code><a href="#workerutils">WorkerUtils</a></code>
2050: interface.</li>
2051:
2052: </ul><p class="note">These requirements do not override the requirements
2053: defined by the Web IDL specification, in particular concerning the
2054: visibility of interfaces annotated with the <code title="">[NoInterfaceObject]</code> extended attribute.<h3 id="worker-locations"><span class="secno">5.5 </span>Worker locations</h3><pre class="idl">interface <dfn id="workerlocation">WorkerLocation</dfn> {
1.115 ihickson 2055: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
2056: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
2057: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
2058: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
2059: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
2060: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
2061: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
2062: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 2063: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
2064: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 2065: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 2066: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 2067: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 2068: <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>,
2069: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
2070: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
2071: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
1.163 ihickson 2072: follow the rules given for URL decomposition IDL attributes, with the
1.115 ihickson 2073: <span title="concept-uda-input">input</span> being the
1.81 ihickson 2074: <span>absolute URL</span> that the object represents (same as the
1.115 ihickson 2075: <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and
2076: the <span title="concept-uda-setter">common setter action</span>
1.205 ihickson 2077: being a no-op, since the attributes are defined to be readonly.
2078:
1.226 ihickson 2079: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2080:
1.209 ihickson 2081: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface must not exist if the
2082: interface's <span>relevant namespace object</span> is a
1.251 ihickson 2083: <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 2084: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
2085: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
2086: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1.226 ihickson 2087: S. Byrnes. W3C.</dd>
1.153 ihickson 2088: <!--
2089: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
1.226 ihickson 2090: DOM Core</a></cite>, S. Pieters. W3C.</dd>
1.153 ihickson 2091: -->
2092:
1.152 ihickson 2093: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
2094: <!--
2095: <dd><cite><a
2096: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
2097: Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2098: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C.</dd>
1.152 ihickson 2099: -->
2100: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
2101: Object Model (DOM) Level 3 Events Specification</a></cite>,
1.226 ihickson 2102: D. Schepers. W3C.</dd>
1.152 ihickson 2103:
2104: <dt id="refsECMA262">[ECMA262]</dt>
2105: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1.226 ihickson 2106: Language Specification</a></cite>. ECMA.</dd>
1.152 ihickson 2107:
1.226 ihickson 2108: <dt id="refsHTML">[HTML]</dt>
2109: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML</a></cite>,
2110: I. Hickson. WHATWG.</dd>
1.152 ihickson 2111:
1.154 ihickson 2112: <dt id="refsRFC2119">[RFC2119]</dt>
2113: <dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
1.226 ihickson 2114: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF.</dd>
1.154 ihickson 2115:
2116: <dt id="refsWEBIDL">[WEBIDL]</dt>
2117: <!--
2118: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
1.226 ihickson 2119: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2120: -->
2121: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
1.226 ihickson 2122: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2123:
1.230 ihickson 2124: <dt id="refsWEBSQL">[WEBSQL]</dt>
2125: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web SQL
2126: Database</a></cite>, I. Hickson. W3C.</dd>
2127:
1.152 ihickson 2128: <dt id="refsXHR">[XHR]</dt>
2129: <!--
2130: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
1.226 ihickson 2131: Object</a></cite>, A. van Kesteren. W3C.</dd>
1.152 ihickson 2132: -->
1.160 ihickson 2133: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.226 ihickson 2134: A. van Kesteren. W3C.</dd>
1.152 ihickson 2135:
1.221 ihickson 2136: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2137:
2138: Aaron Boodman,
1.155 ihickson 2139: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2140: Anne van Kesteren,
2141: Ben Turner,
2142: Dmitry Titov,
1.96 ihickson 2143: Drew Wilson,
1.97 ihickson 2144: Jeremy Orlow,
1.81 ihickson 2145: Jonas Sicking,
2146: Justin James,
2147: Kevin Hakanson,
2148: Maciej Stachowiak,
2149: Michael Nordman,
2150: Mike Smith,
2151:
2152: and
2153:
2154: Philip Taylor
2155:
1.155 ihickson 2156: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2157: technology and whose experience has been a huge influence on this
1.155 ihickson 2158: specification.
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