Annotation of html5/workers/Overview.html, revision 1.206
1.155 ihickson 1: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!-- when publishing, change bits marked ZZZ --><html lang="en-US-x-Hixie"><title>Web Workers</title><style type="text/css">
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1.198 ihickson 168: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><div class="head">
1.115 ihickson 169: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
1.54 ihickson 170: <h1>Web Workers</h1>
1.196 ihickson 171:
1.206 ! ihickson 172: <h2 class="no-num no-toc" id="editor-s-draft-6-december-2009">Editor's Draft 6 December 2009</h2>
1.198 ihickson 173: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 174: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 175: <dt>Latest Editor's Draft:</dt>
1.115 ihickson 176: <dd><a href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.117 ihickson 177: <!-- ZZZ: add the new version after it has shipped-->
1.2 ihickson 178: <dt>Previous Versions:</dt>
1.113 ihickson 179: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20090423/">http://www.w3.org/TR/2009/WD-workers-20090423/</a>
1.198 ihickson 180: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20091029/">http://www.w3.org/TR/2009/WD-workers-20091029/</a></dd>
1.117 ihickson 181: <!-- :ZZZ -->
1.81 ihickson 182: <dt>Editors:</dt>
1.115 ihickson 183: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 184: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
185: © 2009 <a href="http://www.w3.org/"><abbr title="World Wide
186: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.115 ihickson 187: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr title="European Research
188: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
189: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
190: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
191: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 192: use</a> rules apply.</p>
1.201 ihickson 193:
194: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
195: <p class="alt copyright">The <a href="http://www.whatwg.org/specs/web-workers/current-work/">WHATWG
196: version</a> of this specification is available under a license that
197: permits reuse of the specification text.</p>
198: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
199:
1.155 ihickson 200: </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 201: authors to spawn background workers running scripts in parallel to
202: their main page. This allows for thread-like operation with
1.155 ihickson 203: 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 204: time of its publication. Other documents may supersede this
205: document. A list of current W3C publications and the most recently
206: formally published revision of this technical report can be found in
1.115 ihickson 207: the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
1.201 ihickson 208: 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 209: them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>
1.90 ihickson 210: (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.115 ihickson 211: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>)
1.81 ihickson 212:
213: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.115 ihickson 214: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
215: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.110 ihickson 216: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.1 ihickson 217:
1.155 ihickson 218: All feedback is welcome.</p><!-- stability (required) --><p>Implementors should be aware that this specification is not
1.81 ihickson 219: stable. <strong>Implementors who are not taking part in the
220: discussions are likely to find the specification changing out from
221: under them in incompatible ways.</strong> Vendors interested in
222: implementing this specification before it eventually reaches the
223: Candidate Recommendation stage should join the aforementioned
1.155 ihickson 224: mailing lists and take part in the discussions.</p><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- version history or list of changes (required) --><p>The latest stable version of the editor's draft of this
1.115 ihickson 225: specification is always available on <a href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
226: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG Subversion
1.81 ihickson 227: repository</a>. The latest editor's working copy (which may contain
1.115 ihickson 228: unfinished text in the process of being prepared) is available <a href="http://www.whatwg.org/specs/web-workers/current-work/">on the
1.81 ihickson 229: WHATWG site</a>. Detailed change history can be obtained from the
1.155 ihickson 230: following locations:</p><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><ul><li>Twitter messages (non-editorial changes only): <a href="http://twitter.com/WHATWG">http://twitter.com/WHATWG</a></li>
1.115 ihickson 231: <li>Interactive Web interface: <a href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a></li>
232: <li>Commit-Watchers mailing list: <a href="http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org">http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></li>
233: <li>Subversion interface: <a href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a></li>
234: <li>CVS log: <a href="http://dev.w3.org/cvsweb/html5/workers/Overview.html">http://dev.w3.org/cvsweb/html5/workers/Overview.html</a></li>
1.155 ihickson 235: </ul><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- status of document, group responsible (required) --><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Apps
1.81 ihickson 236: Working Group</a> is the W3C working group responsible for this
237: specification's progress along the W3C Recommendation track.
1.196 ihickson 238:
1.206 ! ihickson 239: This specification is the 6 December 2009 Editor's Draft.
1.155 ihickson 240: </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
241: 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 242: platform closely related to HTML5. It is defined in a separate
1.155 ihickson 243: 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 244: 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 245: any patent disclosures</a> made in connection with the deliverables
246: of the group; that page also includes instructions for disclosing a
247: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 248: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
249: Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
1.155 ihickson 250: 6 of the W3C Patent Policy</a>.<h2 class="no-num no-toc" id="contents">Table of contents</h2>
1.81 ihickson 251: <!--begin-toc-->
1.115 ihickson 252: <ol class="toc">
253: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 254: <ol>
1.115 ihickson 255: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
256: <li><a href="#tutorial"><span class="secno">1.2 </span>Tutorial</a>
1.81 ihickson 257: <ol>
1.115 ihickson 258: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
259: <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>
260: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.3 </span>Worker used for background I/O</a></li>
261: <li><a href="#shared-workers"><span class="secno">1.2.4 </span>Shared workers</a></li>
262: <li><a href="#delegation"><span class="secno">1.2.5 </span>Delegation</a></li>
263: <li><a href="#providing-libraries"><span class="secno">1.2.6 </span>Providing libraries</a></ol></ol></li>
1.148 ihickson 264: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 265: <ol>
1.148 ihickson 266: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
267: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
268: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
269: <ol>
270: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 271: <ol>
1.148 ihickson 272: <li><a href="#the-workerglobalscope-abstract-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></li>
273: <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>
274: <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 275: <li><a href="#origins-of-workers"><span class="secno">4.2 </span>Origins of workers</a></li>
1.186 ihickson 276: <li><a href="#the-event-loop"><span class="secno">4.3 </span>The event loop</a></li>
277: <li><a href="#the-worker-s-lifetime"><span class="secno">4.4 </span>The worker's lifetime</a></li>
278: <li><a href="#processing-model"><span class="secno">4.5 </span>Processing model</a></li>
279: <li><a href="#runtime-script-errors"><span class="secno">4.6 </span>Runtime script errors</a></li>
280: <li><a href="#creating-workers"><span class="secno">4.7 </span>Creating workers</a>
1.81 ihickson 281: <ol>
1.186 ihickson 282: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
283: <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>
284: <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 285: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 286: <ol>
1.148 ihickson 287: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
288: <li><a href="#the-navigator-object"><span class="secno">5.2 </span>The <code title="worker-Navigator">Navigator</code> object</a></li>
289: <li><a href="#apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</a></li>
290: <li><a href="#interface-objects-and-constructors"><span class="secno">5.4 </span>Interface objects and constructors</a></li>
291: <li><a href="#worker-locations"><span class="secno">5.5 </span>Worker locations</a></ol></li>
1.115 ihickson 292: <li><a class="no-num" href="#references">References</a></li>
293: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.155 ihickson 294: <!--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
295: background independently of any user interface scripts.<p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 296: scripts that respond to clicks or other user interactions, and
297: allows long tasks to be executed without yielding to keep the page
1.155 ihickson 298: responsive.<p>Workers (as these background scripts are called herein) are
1.81 ihickson 299: relatively heavy-weight, and are not intended to be used in large
300: numbers. For example, it would be inappropriate to launch one worker
301: for each pixel of a four megapixel image. The examples below show
1.155 ihickson 302: some appropriate uses of workers.<p>Generally, workers are expected to be long-lived, have a high
303: 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
304: 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
305: expensive task without interrupting the user interface.<p>In this example, the main document spawns a worker to
306: (naïvely) compute prime numbers, and progressively displays the
307: most recently found prime number.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 308: <html>
309: <head>
310: <title>Worker example: One-core computation</title>
311: </head>
312: <body>
313: <p>The highest prime number discovered so far is: <output id="result"></output></p>
314: <script>
1.50 ihickson 315: var worker = new Worker('worker.js');
316: worker.onmessage = function (event) {
1.54 ihickson 317: document.getElementById('result').textContent = event.data;
1.29 ihickson 318: };
1.81 ihickson 319: </script>
320: </body>
1.155 ihickson 321: </html></pre><p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 322: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 323: representing that worker, which is used to communicate with the
1.177 ihickson 324: 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 325: search: while (true) {
326: n += 1;
327: for (var i = 2; i <= Math.sqrt(n); i += 1)
328: if (n % i == 0)
329: continue search;
330: // found a prime!
1.50 ihickson 331: postMessage(n);
1.155 ihickson 332: }</pre><p>The bulk of this code is simply an unoptimized search for a prime
1.115 ihickson 333: 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 334: 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 335: task is to listen for notifications from the server, and, when
336: appropriate, either add or remove data from the client-side
1.155 ihickson 337: database.<p>Since no communication occurs between the worker and the main
338: page, the main page can start the worker by just doing:<pre><script>
1.50 ihickson 339: new Worker('worker.js');
1.155 ihickson 340: </script></pre><p>The worker itself is as follows:<pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ihickson 341: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 342: server.onmessage = function (event) {
343: // data is in the format "command key value"
1.54 ihickson 344: var data = event.data.split(' ');
1.31 ihickson 345: switch (data[0]) {
346: case '+':
347: database.transaction(function(tx) {
348: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
349: });
350: case '-':
351: database.transaction(function(tx) {
352: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
353: });
354: }
1.155 ihickson 355: };</pre><p>This connects to the server using the <code>WebSocket</code>
1.81 ihickson 356: mechanism and opens the local database (which, we presume, has been
357: created earlier). The worker then just listens for messages from the
358: server and acts on them as appropriate, forever (or until the main
1.155 ihickson 359: page is closed).<p><a href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
1.81 ihickson 360: this example online</a>. (This example will not actually function,
361: since the server does not actually exist and the database is not
1.155 ihickson 362: 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 363: fetching stock updates for at regular intervals, and one for
1.155 ihickson 364: fetching performing search queries that the user requests.<p>The main page is as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 365: <html>
366: <head>
367: <title>Worker example: Stock ticker</title>
368: <script>
1.33 ihickson 369: // TICKER
370: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 371: var ticker = new Worker('ticker.js');
1.33 ihickson 372:
373: // SEARCHER
1.50 ihickson 374: var searcher = new Worker('searcher.js');
1.33 ihickson 375: function search(query) {
1.50 ihickson 376: searcher.postMessage(query);
1.33 ihickson 377: }
378:
379: // SYMBOL SELECTION UI
380: function select(newSymbol) {
381: symbol = newSymbol;
1.50 ihickson 382: ticker.postMessage(symbol);
1.33 ihickson 383: }
1.81 ihickson 384: </script>
385: </head>
1.122 ihickson 386: <body onload="search('')">
1.81 ihickson 387: <p><output id="symbol"></output> <output id="value"></output></p>
388: <script>
1.50 ihickson 389: ticker.onmessage = function (event) {
1.54 ihickson 390: var data = event.data.split(' ');
1.33 ihickson 391: document.getElementById('symbol').textContent = data[0];
392: document.getElementById('value').textContent = data[1];
393: };
1.50 ihickson 394: ticker.postMessage(symbol);
1.81 ihickson 395: </script>
1.122 ihickson 396: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 397: <ul id="results"></ul>
398: <script>
1.50 ihickson 399: searcher.onmessage = function (event) {
1.54 ihickson 400: var data = event.data.split(' ');
1.33 ihickson 401: var results = document.getElementById('results');
402: while (results.hasChildNodes()) // clear previous results
403: results.removeChild(results.firstChild);
404: for (var i = 0; i < data.length; i += 1) {
405: // add a list item with a button for each result
406: var li = document.createElement('li');
407: var button = document.createElement('button');
408: button.value = data[i];
409: button.type = 'button';
410: button.onclick = function () { select(this.value); };
411: button.textContent = data[i];
412: li.appendChild(button);
413: results.appendChild(li);
414: }
415: };
1.81 ihickson 416: </script>
417: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
418: </body>
1.155 ihickson 419: </html></pre><p>The two workers use a common library for performing the actual
420: network calls. This library is as follows:<pre>function get(url) {
1.50 ihickson 421: try {
422: var xhr = new XMLHttpRequest();
423: xhr.open('GET', url, false);
424: xhr.send();
425: return xhr.responseText;
426: } catch (e) {
427: return ''; // turn all errors into empty results
428: }
1.155 ihickson 429: }</pre><p>The stock updater worker is as follows:<pre>importScripts('io.js');
1.33 ihickson 430: var timer;
431: var symbol;
432: function update() {
1.50 ihickson 433: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 434: timer = setTimeout(update, 10000);
435: }
1.50 ihickson 436: onmessage = function (event) {
1.33 ihickson 437: if (timer)
438: clearTimeout(timer);
1.54 ihickson 439: symbol = event.data;
1.33 ihickson 440: update();
1.155 ihickson 441: };</pre><p>The search query worker is as follows:<pre>importScripts('io.js');
1.50 ihickson 442: onmessage = function (event) {
1.54 ihickson 443: postMessage(get('search.cgi?' + event.data));
1.155 ihickson 444: };</pre><p><a href="http://www.whatwg.org/demos/workers/stocks/page.html">View this example online</a>.<h4 id="shared-workers"><span class="secno">1.2.4 </span>Shared workers</h4><p><i>This section is non-normative.</i><p>In this example, multiple windows (viewers) can be opened that
1.81 ihickson 445: are all viewing the same map. All the windows share the same map
446: information, with a single worker coordinating all the viewers. Each
447: viewer can move around independently, but if they set any data on
1.155 ihickson 448: the map, all the viewers are updated.<p>The main page isn't interesting, it merely provides a way to open
449: the viewers:<pre><!DOCTYPE HTML>
1.81 ihickson 450: <html>
451: <head>
452: <title>Workers example: Multiviewer</title>
453: <script>
1.36 ihickson 454: function openViewer() {
455: window.open('viewer.html');
456: }
1.81 ihickson 457: </script>
458: </head>
459: <body>
460: <p><button type=button onclick="openViewer()">Open a new
461: viewer</button></p>
462: <p>Each viewer opens in a new window. You can have as many viewers
463: as you like, they all view the same data.</p>
464: </body>
1.155 ihickson 465: </html></pre><p>The viewer is more involved:<pre><!DOCTYPE HTML>
1.81 ihickson 466: <html>
467: <head>
468: <title>Workers example: Multiviewer viewer</title>
469: <script>
1.50 ihickson 470: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 471:
472: // CONFIGURATION
473: function configure(event) {
1.54 ihickson 474: if (event.data.substr(0, 4) != 'cfg ') return;
475: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 476: // update display to mention our name is name
477: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
478: // no longer need this listener
1.43 ihickson 479: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 480: }
1.53 ihickson 481: worker.port.addEventListener('message', configure, false);
1.36 ihickson 482:
483: // MAP
484: function paintMap(event) {
1.54 ihickson 485: if (event.data.substr(0, 4) != 'map ') return;
486: var data = event.data.substr(4).split(',');
1.36 ihickson 487: // display tiles data[0] .. data[8]
488: var canvas = document.getElementById('map');
489: var context = canvas.getContext('2d');
490: for (var y = 0; y < 3; y += 1) {
491: for (var x = 0; x < 3; x += 1) {
492: var tile = data[y * 3 + x];
493: if (tile == '0')
494: context.fillStyle = 'green';
495: else
496: context.fillStyle = 'maroon';
497: fillRect(x * 50, y * 50, 50, 50);
498: }
499: }
500: }
1.53 ihickson 501: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 502:
503: // PUBLIC CHAT
504: function updatePublicChat(event) {
1.54 ihickson 505: if (event.data.substr(0, 4) != 'txt ') return;
506: var name = event.data.substr(4).split(' ', 1);
507: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 508: // display "<name> message" in public chat
1.36 ihickson 509: var dialog = document.getElementById('public');
510: var dt = document.createElement('dt');
511: dt.textContent = name;
512: dialog.appendChild(dt);
513: var dd = document.createElement('dd');
514: dd.textContent = message;
515: dialog.appendChild(dd);
516: }
1.53 ihickson 517: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 518:
519: // PRIVATE CHAT
520: function startPrivateChat(event) {
1.54 ihickson 521: if (event.data.substr(0, 4) != 'msg ') return;
522: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 523: var port = event.ports[0];
1.36 ihickson 524: // display a private chat UI
525: var ul = document.getElementById('private');
526: var li = document.createElement('li');
527: var h3 = document.createElement('h3');
528: h3.textContent = 'Private chat with ' + name;
529: li.appendChild(h3);
530: var dialog = document.createElement('dialog');
531: var addMessage = function(name, message) {
532: var dt = document.createElement('dt');
533: dt.textContent = name;
534: dialog.appendChild(dt);
535: var dd = document.createElement('dd');
536: dd.textContent = message;
537: dialog.appendChild(dd);
538: };
539: port.onmessage = function (event) {
1.54 ihickson 540: addMessage(name, event.data);
1.36 ihickson 541: };
542: li.appendChild(dialog);
543: var form = document.createElement('form');
544: var p = document.createElement('p');
545: var input = document.createElement('input');
546: input.size = 50;
547: p.appendChild(input);
548: p.appendChild(document.createTextNode(' '));
549: var button = document.createElement('button');
550: button.textContent = 'Post';
551: p.appendChild(button);
552: form.onsubmit = function () {
553: port.postMessage(input.value);
554: addMessage('me', input.value);
555: input.value = '';
556: return false;
557: };
558: form.appendChild(p);
559: li.appendChild(form);
560: }
1.53 ihickson 561: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 562:
563: worker.port.start();
1.81 ihickson 564: </script>
565: </head>
566: <body>
567: <h1>Viewer</h1>
568: <h2>Map</h2>
569: <p><canvas id="map" height=150 width=150></canvas></p>
570: <p>
571: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
572: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
573: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
574: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
575: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
576: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
577: </p>
578: <h2>Public Chat</h2>
579: <dialog id="public"></dialog>
580: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
581: <p>
582: <input type="text" name="message" size="50">
583: <button>Post</button>
584: </p>
585: </form>
586: <h2>Private Chat</h2>
587: <ul id="private"></ul>
588: </body>
589: </html>
1.155 ihickson 590: </pre><p>There are several key things worth noting about the way the
591: viewer is written.<p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 592: processing function, the code here attaches multiple event
593: listeners, each one performing a quick check to see if it is
594: relevant for the message. In this example it doesn't make much
595: difference, but if multiple authors wanted to collaborate using a
596: single port to communicate with a worker, it would allow for
597: independent code instead of changes having to all be made to a
1.155 ihickson 598: single event handling function.<p>Registering event listeners in this way also allows you to
1.81 ihickson 599: unregister specific listeners when you are done with them, as is
600: done with the <code title="">configure()</code> method in this
1.155 ihickson 601: example.<p>Finally, the worker:<pre>
602: var nextName = 0;
1.36 ihickson 603: function getNextName() {
604: // this could use more friendly names
605: // but for now just return a number
606: return nextName++;
607: }
608:
609: var map = [
610: [0, 0, 0, 0, 0, 0, 0],
611: [1, 1, 0, 1, 0, 1, 1],
612: [0, 1, 0, 1, 0, 0, 0],
613: [0, 1, 0, 1, 0, 1, 1],
614: [0, 0, 0, 1, 0, 0, 0],
615: [1, 0, 0, 1, 1, 1, 1],
616: [1, 1, 0, 1, 1, 0, 1],
617: ];
618:
619: function wrapX(x) {
620: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 621: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 622: return x;
623: }
624:
625: function wrapY(y) {
626: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 627: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 628: return y;
629: }
630:
1.50 ihickson 631: function sendMapData(callback) {
1.36 ihickson 632: var data = '';
633: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
634: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
635: if (data != '')
636: data += ',';
637: data += map[y][x];
638: }
639: }
1.50 ihickson 640: callback('map ' + data);
1.36 ihickson 641: }
642:
643: var viewers = {};
644: onconnect = function (event) {
1.84 ihickson 645: event.ports[0]._name = getNextName();
646: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
647: viewers[event.ports[0]._name] = event.port._data;
648: event.ports[0].postMessage('cfg ' + name);
649: event.ports[0].onmessage = getMessage;
650: sendMapData(event.ports[0].postMessage);
1.36 ihickson 651: };
652:
653: function getMessage(event) {
1.54 ihickson 654: switch (event.data.substr(0, 4)) {
1.36 ihickson 655: case 'mov ':
1.54 ihickson 656: var direction = event.data.substr(4);
1.36 ihickson 657: var dx = 0;
658: var dy = 0;
659: switch (direction) {
660: case 'up': dy = -1; break;
661: case 'down': dy = 1; break;
662: case 'left': dx = -1; break;
663: case 'right': dx = 1; break;
664: }
665: event.target._data.x = wrapX(event.target._data.x + dx);
666: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 667: sendMapData(event.target.postMessage);
1.36 ihickson 668: break;
669: case 'set ':
1.54 ihickson 670: var value = event.data.substr(4);
1.36 ihickson 671: map[event.target._data.y][event.target._data.x] = value;
672: for (var viewer in viewers)
1.50 ihickson 673: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 674: break;
675: case 'txt ':
676: var name = event.target._name;
1.54 ihickson 677: var message = event.data.substr(4);
1.36 ihickson 678: for (var viewer in viewers)
679: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
680: break;
681: case 'msg ':
682: var party1 = event._data;
1.54 ihickson 683: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 684: if (party2) {
685: var channel = new MessageChannel();
1.84 ihickson 686: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
687: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 688: }
689: break;
690: }
1.155 ihickson 691: }</pre><p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 692: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.155 ihickson 693: event listener to listen for multiple connections.<p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 694: "msg" message from one viewer naming another viewer, it sets up a
695: direct connection between the two, so that the two viewers can
696: communicate directly without the worker having to proxy all the
1.155 ihickson 697: messages.<p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View this example online</a>.<h4 id="delegation"><span class="secno">1.2.5 </span>Delegation</h4><p><i>This section is non-normative.</i><p>With multicore CPUs becoming prevalent, one way to obtain better
1.81 ihickson 698: performance is to split computationally expensive tasks amongst
699: multiple workers. In this example, a computationally expensive task
700: that is to be performed for every number from 1 to 10,000,000 is
1.155 ihickson 701: farmed out to ten subworkers.<p>The main page is as follows, it just reports the result:<pre><!DOCTYPE HTML>
1.81 ihickson 702: <html>
703: <head>
1.203 ihickson 704: <title>Worker example: Multicore computation</title>
1.81 ihickson 705: </head>
706: <body>
1.203 ihickson 707: <p>Result: <output id="result"></output></p>
1.81 ihickson 708: <script>
1.50 ihickson 709: var worker = new Worker('worker.js');
710: worker.onmessage = function (event) {
1.54 ihickson 711: document.getElementById('result').textContent = event.data;
1.40 ihickson 712: };
1.81 ihickson 713: </script>
714: </body>
1.155 ihickson 715: </html></pre><p>The worker itself is as follows:<pre>// settings
1.40 ihickson 716: var num_workers = 10;
717: var items_per_worker = 1000000;
718:
719: // start the workers
720: var result = 0;
721: var pending_workers = num_workers;
722: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 723: var worker = new Worker('core.js');
724: worker.postMessage(i * items_per_worker);
725: worker.postMessage((i+1) * items_per_worker);
726: worker.onmessage = storeResult;
1.40 ihickson 727: }
728:
729: // handle the results
730: function storeResult(event) {
1.54 ihickson 731: result += 1*event.data;
1.40 ihickson 732: pending_workers -= 1;
733: if (pending_workers <= 0)
1.50 ihickson 734: postMessage(result); // finished!
1.155 ihickson 735: }</pre><p>It consists of a loop to start the subworkers, and then a handler
736: that waits for all the subworkers to respond.<p>The subworkers are implemented as follows:<pre>var start;
1.41 ihickson 737: onmessage = getStart;
1.40 ihickson 738: function getStart(event) {
1.54 ihickson 739: start = 1*event.data;
1.40 ihickson 740: onmessage = getEnd;
741: }
742:
743: var end;
744: function getEnd(event) {
1.54 ihickson 745: end = 1*event.data;
1.40 ihickson 746: onmessage = null;
1.66 ihickson 747: work();
1.40 ihickson 748: }
749:
1.66 ihickson 750: function work() {
1.40 ihickson 751: var result = 0;
752: for (var i = start; i < end; i += 1) {
753: // perform some complex calculation here
754: result += 1;
755: }
1.50 ihickson 756: postMessage(result);
757: close();
1.155 ihickson 758: }</pre><p>They receive two numbers in two events, perform the computation
1.81 ihickson 759: for the range of numbers thus specified, and then report the result
1.155 ihickson 760: back to the parent.<p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.<h4 id="providing-libraries"><span class="secno">1.2.6 </span>Providing libraries</h4><p><i>This section is non-normative.</i><p>Suppose that a cryptography library is made available that
761: provides three tasks:<dl><dt>Generate a public/private key pair</dt>
1.81 ihickson 762:
763: <dd>Takes a port, on which it will send two messages, first the
764: public key and then the private key.</dd>
765:
766: <dt>Given a plaintext and a public key, return the corresponding cyphertext</dt>
767:
768: <dd>Takes a port, to which any number of messages can be sent, the
769: first giving the public key, and the remainder giving the
770: plaintext, each of which is encrypted and then sent on that same
771: channel as the cyphertext. The user can close the port when it is
772: done encrypting content.</dd>
773:
774: <dt>Given a cyphertext and a private key, return the corresponding plaintext</dt>
775:
776: <dd>Takes a port, to which any number of messages can be sent, the
777: first giving the private key, and the remainder giving the
778: cyphertext, each of which is decrypted and then sent on that same
779: channel as the plaintext. The user can close the port when it is
780: done decrypting content.</dd>
1.49 ihickson 781:
1.155 ihickson 782: </dl><p>The library itself is as follows:<pre>function handleMessage(e) {
1.54 ihickson 783: if (e.data == "genkeys")
1.84 ihickson 784: genkeys(e.ports[0]);
1.54 ihickson 785: else if (e.data == "encrypt")
1.84 ihickson 786: encrypt(e.ports[0]);
1.54 ihickson 787: else if (e.data == "decrypt")
1.84 ihickson 788: decrypt(e.ports[0]);
1.49 ihickson 789: }
790:
791: function genkeys(p) {
792: var keys = _generateKeyPair();
793: p.postMessage(keys[0]);
794: p.postMessage(keys[1]);
795: }
796:
797: function encrypt(p) {
798: var key, state = 0;
799: p.onmessage = function (e) {
800: if (state == 0) {
1.54 ihickson 801: key = e.data;
1.49 ihickson 802: state = 1;
803: } else {
1.54 ihickson 804: p.postMessage(_encrypt(key, e.data));
1.49 ihickson 805: }
806: };
807: }
808:
809: function decrypt(p) {
810: var key, state = 0;
811: p.onmessage = function (e) {
812: if (state == 0) {
1.54 ihickson 813: key = e.data;
1.49 ihickson 814: state = 1;
815: } else {
1.54 ihickson 816: p.postMessage(_decrypt(key, e.data));
1.49 ihickson 817: }
818: };
819: }
820:
1.50 ihickson 821: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 822: if ('onmessage' in this) // dedicated worker
1.50 ihickson 823: onmessage = handleMessage;
824: else // shared worker
825: onconnect = function (e) { e.port.onmessage = handleMessage; }
1.49 ihickson 826:
827:
828: // the "crypto" functions:
829:
830: function _generateKeyPair() {
831: return [Math.random(), Math.random()];
832: }
833:
834: function _encrypt(k, s) {
835: return 'encrypted-' + k + ' ' + s;
836: }
837:
838: function _decrypt(k, s) {
839: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 840: }</pre><p>Note that the crypto functions here are just stubs and don't do
841: real cryptography.<p>This library could be used as follows:<pre><!DOCTYPE HTML>
1.81 ihickson 842: <html>
843: <head>
844: <title>Worker example: Crypto library</title>
845: <script>
1.50 ihickson 846: var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
1.49 ihickson 847: function getKeys() {
848: var state = 0;
1.50 ihickson 849: cryptoLib.startConversation("genkeys").onmessage = function (e) {
1.49 ihickson 850: if (state == 0)
1.54 ihickson 851: document.getElementById('public').value = e.data;
1.49 ihickson 852: else if (state == 1)
1.54 ihickson 853: document.getElementById('private').value = e.data;
1.49 ihickson 854: state += 1;
855: };
856: }
857: function enc() {
1.50 ihickson 858: var port = cryptoLib.startConversation("encrypt");
859: port.postMessage(document.getElementById('public').value);
860: port.postMessage(document.getElementById('input').value);
861: port.onmessage = function (e) {
1.54 ihickson 862: document.getElementById('input').value = e.data;
1.50 ihickson 863: port.close();
1.49 ihickson 864: };
865: }
866: function dec() {
1.50 ihickson 867: var port = cryptoLib.startConversation("decrypt");
868: port.postMessage(document.getElementById('private').value);
869: port.postMessage(document.getElementById('input').value);
870: port.onmessage = function (e) {
1.54 ihickson 871: document.getElementById('input').value = e.data;
1.50 ihickson 872: port.close();
1.49 ihickson 873: };
874: }
1.81 ihickson 875: </script>
876: <style>
1.49 ihickson 877: textarea { display: block; }
1.81 ihickson 878: </style>
879: </head>
880: <body onload="getKeys()">
881: <fieldset>
882: <legend>Keys</legend>
883: <p><label>Public Key: <textarea id="public"></textarea></label></p>
884: <p><label>Private Key: <textarea id="private"></textarea></label></p>
885: </fieldset>
886: <p><label>Input: <textarea id="input"></textarea></label></p>
887: <p><button onclick="enc()">Encrypt</button> <button onclick="dec()">Decrypt</button></p>
888: </body>
1.155 ihickson 889: </html></pre><p>A later version of the API, though, might want to offload all the
890: crypto work onto subworkers. This could be done as follows:<pre>function handleMessage(e) {
1.54 ihickson 891: if (e.data == "genkeys")
1.84 ihickson 892: genkeys(e.ports[0]);
1.54 ihickson 893: else if (e.data == "encrypt")
1.84 ihickson 894: encrypt(e.ports[0]);
1.54 ihickson 895: else if (e.data == "decrypt")
1.84 ihickson 896: decrypt(e.ports[0]);
1.49 ihickson 897: }
898:
899: function genkeys(p) {
1.50 ihickson 900: var generator = new Worker('libcrypto-v2-generator.js');
1.84 ihickson 901: generator.postMessage('', [p]);
1.49 ihickson 902: }
903:
904: function encrypt(p) {
905: p.onmessage = function (e) {
1.54 ihickson 906: var key = e.data;
1.50 ihickson 907: var encryptor = new Worker('libcrypto-v2-encryptor.js');
1.84 ihickson 908: encryptor.postMessage(key, [p]);
1.49 ihickson 909: };
910: }
911:
912: function encrypt(p) {
913: p.onmessage = function (e) {
1.54 ihickson 914: var key = e.data;
1.50 ihickson 915: var decryptor = new Worker('libcrypto-v2-decryptor.js');
1.84 ihickson 916: decryptor.postMessage(key, [p]);
1.49 ihickson 917: };
918: }
919:
1.50 ihickson 920: // support being used as a shared worker as well as a dedicated worker
1.195 ihickson 921: if ('onmessage' in this) // dedicated worker
1.50 ihickson 922: onmessage = handleMessage;
923: else // shared worker
1.84 ihickson 924: onconnect = function (e) { e.ports[0].onmessage = handleMessage };
1.155 ihickson 925: </pre><p>The little subworkers would then be as follows.<p>For generating key pairs:<pre>onmessage = function (e) {
1.50 ihickson 926: var k = _generateKeyPair();
1.84 ihickson 927: e.ports[0].postMessage(k[0]);
928: e.ports[0].postMessage(k[1]);
1.49 ihickson 929: close();
930: }
1.50 ihickson 931:
932: function _generateKeyPair() {
933: return [Math.random(), Math.random()];
1.155 ihickson 934: }</pre><p>For encrypting:<pre>onmessage = function (e) {
1.54 ihickson 935: var key = e.data;
1.84 ihickson 936: e.ports[0].onmessage = function (e) {
1.54 ihickson 937: var s = e.data;
1.50 ihickson 938: postMessage(_encrypt(key, s));
1.49 ihickson 939: }
1.50 ihickson 940: }
941:
942: function _encrypt(k, s) {
943: return 'encrypted-' + k + ' ' + s;
1.155 ihickson 944: }</pre><p>For decrypting:<pre>onmessage = function (e) {
1.54 ihickson 945: var key = e.data;
1.84 ihickson 946: e.ports[0].onmessage = function (e) {
1.54 ihickson 947: var s = e.data;
1.50 ihickson 948: postMessage(_decrypt(key, s));
1.49 ihickson 949: }
1.50 ihickson 950: }
951:
952: function _decrypt(k, s) {
953: return s.substr(s.indexOf(' ')+1);
1.155 ihickson 954: }</pre><p>Notice how the users of the API don't have to even know that this
955: is happening — the API hasn't changed; the library can
1.81 ihickson 956: delegate to subworkers without changing its API, even though it is
1.155 ihickson 957: 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 958: non-normative, as are all sections explicitly marked non-normative.
1.155 ihickson 959: Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
1.81 ihickson 960: NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
961: "OPTIONAL" in the normative parts of this document are to be
962: interpreted as described in RFC2119. For readability, these words do
1.155 ihickson 963: 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 964: (such as "strip any leading space characters" or "return false and
965: abort these steps") are to be interpreted with the meaning of the
966: key word ("must", "should", "may", etc) used in introducing the
1.155 ihickson 967: algorithm.<p>Some conformance requirements are phrased as requirements on
1.81 ihickson 968: attributes, methods or objects. Such requirements are to be
1.155 ihickson 969: interpreted as requirements on user agents.<p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 970: may be implemented in any manner, so long as the end result is
971: equivalent. (In particular, the algorithms defined in this
972: specification are intended to be easy to follow, and not intended to
1.155 ihickson 973: be performant.)<p>The only conformance class defined by this specification is user
974: agents.<p>User agents may impose implementation-specific limits on
1.81 ihickson 975: otherwise unconstrained inputs, e.g. to prevent denial of service
976: attacks, to guard against running out of memory, or to work around
1.155 ihickson 977: platform-specific limitations.<h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3><p>This specification relies on several other underlying
978: specifications.<dl><dt>HTML5</dt>
1.49 ihickson 979:
1.81 ihickson 980: <dd>
1.49 ihickson 981:
1.81 ihickson 982: <p>Many fundamental concepts from HTML5 are used by this
1.152 ihickson 983: specification. <a href="#refsHTML5">[HTML5]</a></p>
1.49 ihickson 984:
1.81 ihickson 985: </dd>
1.1 ihickson 986:
1.81 ihickson 987: <dt>WebIDL</dt>
1.1 ihickson 988:
989: <dd>
990:
1.81 ihickson 991: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 992: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 993:
1.81 ihickson 994: </dd>
1.1 ihickson 995:
1.155 ihickson 996: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2><p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 997: <code title="">Foo</code> is actually an interface, is sometimes
998: used instead of the more accurate "an object implementing the
1.155 ihickson 999: interface <code title="">Foo</code>".<p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1000: scripts in Web applications, and does not necessarily imply the
1001: existence of an actual <code>Document</code> object or of any other
1002: <code>Node</code> objects as defined in the DOM Core
1.171 ihickson 1003: specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1004: being retrieved (e.g. by author script), and is said to be
1.155 ihickson 1005: <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 1006: the official term ECMAScript, since the term JavaScript is more
1.155 ihickson 1007: 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 1008: workers. Dedicated workers, once created, and are linked to their
1009: creator; but message ports can be used to communicate from a
1010: dedicated worker to multiple other browsing contexts or
1011: workers. Shared workers, on the other hand, are named, and once
1012: created any script running in the same <span>origin</span> can
1.155 ihickson 1013: 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 1014: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1015: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1016:
1017: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.144 ihickson 1018: <!-- v2-onclose attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
1019: --> attribute <span>Function</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.150 ihickson 1020: };
1.172 ihickson 1021: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;
1022: <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 1023: 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 1024: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1025: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1026: created. It represents the <span>absolute URL</span> of the script
1.155 ihickson 1027: 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 1028: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.155 ihickson 1029: must run the following steps (atomically):<ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1030: have been added to the <span>event loop</span>'s <span title="task
1031: queue">task queues</span>.</p>
1032:
1033: <!-- v2-onclose
1034: <li><p><span>Queue a task</span> to <span>fire a simple
1.179 ihickson 1035: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1036: <code>WorkerGlobalScope</code> object.</p></li>
1037: -->
1.81 ihickson 1038:
1.115 ihickson 1039: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1040: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1041: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1042:
1.124 ihickson 1043: <li><p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1.123 ihickson 1044: ports</a>.</li>
1.81 ihickson 1045:
1.177 ihickson 1046: </ol><p>The following are the <span>event handlers</span> (and their
1047: corresponding <span title="event handler event type">event handler
1048: event types</span>) that must be supported, as IDL attributes, by
1049: objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1050: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1051: <tbody><!-- v2-onclose <tr><td><dfn title="handler-WorkerGlobalScope-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> --><tr><td><dfn id="handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1052: </table><h4 id="dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.1.2 </span>Dedicated workers and the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> interface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1053: interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.174 ihickson 1054: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.77 ihickson 1055: <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1056: attribute <span>Function</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.155 ihickson 1057: };</pre><p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.81 ihickson 1058: had an implicit <code>MessagePort</code> associated with them. This
1059: port is part of a channel that is set up when the worker is created,
1060: but it is not exposed. This object must never be garbage collected
1.155 ihickson 1061: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>All messages received by that port must immediately be retargeted
1062: at the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.<p>The <dfn id="dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage"><code>postMessage()</code></dfn><!--
1.64 ihickson 1063: and <dfn
1064: title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
1.81 ihickson 1065: method<!--s (startConversation)--> on
1.115 ihickson 1066: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.81 ihickson 1067: invoked, it<!--/they (startConversation)--> immediately invoked the
1068: method of the same name on the port, with the same arguments, and
1.177 ihickson 1069: returned the same return value.<p>The following are the <span>event handlers</span> (and their
1070: corresponding <span title="event handler event type">event handler
1071: event types</span>) that must be supported, as IDL attributes, by
1072: objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1073: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1074: <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 1075: </table><p>For the purposes of the <span>application cache</span> networking
1076: model, a dedicated worker is an extension of the <span>cache
1077: host</span> from which it was created.<h4 id="shared-workers-and-the-sharedworkerglobalscope-inteface"><span class="secno">4.1.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> inteface</h4><pre class="idl">[Supplemental, NoInterfaceObject]
1.150 ihickson 1078: interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1079: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1080: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.144 ihickson 1081: attribute <span>Function</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.155 ihickson 1082: };</pre><p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1083: their global object for each connection.<p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1084: attribute must return the value it was assigned when the
1.115 ihickson 1085: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1086: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1087: that can be used to obtain a reference to the worker using the
1.177 ihickson 1088: <code><a href="#sharedworker">SharedWorker</a></code> constructor.<p>The following are the <span>event handlers</span> (and their
1089: corresponding <span title="event handler event type">event handler
1090: event types</span>) that must be supported, as IDL attributes, by
1091: objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1092: interface:<table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1093: <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 1094: </table><p>For the purposes of the <span>application cache</span> networking
1095: model, a shared worker is its own <span>cache host</span>. The
1096: <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1097: worker with an <span>application cache</span>.<p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
1.123 ihickson 1098: attribute returns the <code>ApplicationCache</code> object for the
1.101 ihickson 1099: worker.</p><!-- normative conf criteria is in the appcache section
1.160 ihickson 1100: --><h3 id="origins-of-workers"><span class="secno">4.2 </span>Origins of workers</h3><p>Both the <span>origin</span> and <span>effective script
1.81 ihickson 1101: origin</span> of scripts running in workers are the
1102: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1103: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.186 ihickson 1104: 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 1105: loop</span> distinct from those defined for <span title="unit of
1106: related similar-origin browsing contexts">units of related
1107: similar-origin browsing contexts</span>. This <span>event
1108: loop</span> has no associated <span>browsing context</span>, and its
1109: <span title="task queue">task queues</span> only have events,
1110: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1111: <span title="event loop">event loops</span> is defined below in the
1.155 ihickson 1112: <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 1113: initially be false, but which can get set to true by the algorithms
1.155 ihickson 1114: 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 1115: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1116: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1117: already on the queue are unaffected except where otherwise
1.115 ihickson 1118: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1119: timers stop firing, notifications for all pending asynchronous
1.186 ihickson 1120: 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 1121: <code>MessagePort</code> objects.<p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1122: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.81 ihickson 1123: consists of all the <code>MessagePort</code> objects that are
1124: entangled with another port and that have one (but only one) port
1125: owned by <var title="">worker global scope</var>. This list includes
1126: <!--all the <code>MessagePort</code> objects that are in events
1.68 ihickson 1127: pending in the <span>event loop</span>, as well as (commented out
1128: because in practice it makes no difference either way as far as I
1129: can tell, and it would be hard to strictly implement since these
1.81 ihickson 1130: ports might not yet be across the thread boundary)--> the implicit
1.155 ihickson 1131: <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 1132: worker's workers</dfn>. Initially this list is empty; it is
1.155 ihickson 1133: 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 1134: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.155 ihickson 1135: 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 1136: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.124 ihickson 1137: worker in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list
1138: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> does not contain
1139: <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 1140: documents">add <var title="">d</var> to <var title="">q</var>'s
1141: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.155 ihickson 1142: <code>Document</code>s</span></a>.</p><!-- suggestions welcome
1143: on making this sentence into understandable English --><p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1144: Document">discarded</span>, it must be removed from the list of
1145: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.192 ihickson 1146: whose list contains that <code>Document</code>.<p>Given a <span>script's global object</span> <var title="">o</var>
1.123 ihickson 1147: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1148: <code>Document</code> objects to add</dfn> depends on the type of
1149: <var title="">o</var>. If <var title="">o</var> is a
1150: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1151: nested worker), then the relevant <code>Document</code>s are the
1152: <code>Document</code>s that are in <var title="">o</var>'s own list
1153: 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
1154: <code>Document</code> is just the <code>Document</code> that is the
1.155 ihickson 1155: <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 1156: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.155 ihickson 1157: empty.<p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1158: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1159: timers, database transactions, or network connections, or its list
1.124 ihickson 1160: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1161: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1162: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.155 ihickson 1163: shared worker).<p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1164: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.155 ihickson 1165: <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 1166: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.186 ihickson 1167: <a href="#permissible-worker">permissible worker</a>.<h3 id="processing-model"><span class="secno">4.5 </span>Processing model</h3><p>When a user agent is to <dfn id="run-a-worker">run a worker</dfn> for a script with
1.176 ihickson 1168: <span>URL</span> <var title="">url</var>, a browsing context <var title="">owner browsing context</var>, an origin <var title="">owner
1169: origin</var>, and with global scope <var title="">worker global
1170: scope</var>, it must run the following steps:<ol><li>
1.81 ihickson 1171:
1172: <p>Create a completely separate and parallel execution environment
1173: (i.e. a separate thread or process or equivalent construct), and
1.106 ihickson 1174: run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1175:
1176: </li>
1.4 ihickson 1177:
1.101 ihickson 1178: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1179: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1180: shared worker), and there are any <span title="relevant application
1181: cache">relevant application caches</span> that are identified by a
1182: 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 1183: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1184: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1185: cache</span> of those that match.</li>
1186:
1.4 ihickson 1187: <li>
1.52 ihickson 1188:
1.176 ihickson 1189: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>.</p>
1190: <!-- not http-origin privacy sensitive -->
1.81 ihickson 1191:
1.129 ihickson 1192: <p>If the attempt fails, or if the attempt involves any redirects
1193: to URIs that do not have the <span>same origin</span> as <var title="">url</var> (even if the final URI is at the <span>same
1194: origin</span> as the original <var title="">url</var>), then for
1195: each <code><a href="#worker">Worker</a></code> or <code><a href="#sharedworker">SharedWorker</a></code> object
1196: associated with <var title="">worker global scope</var>,
1197: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1198: named <code title="event-error">error</code> at that
1.129 ihickson 1199: object. Abort these steps.</p>
1.7 ihickson 1200:
1.186 ihickson 1201: <p>If the attempt succeeds, then convert the script resource to
1202: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.81 ihickson 1203:
1.68 ihickson 1204: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1205:
1.115 ihickson 1206: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1207: type of the script is ignored. Unlike with <code>script</code>
1208: elements, there is no way to override the type. It's always
1.170 ihickson 1209: assumed to be JavaScript.</p>
1.81 ihickson 1210:
1211: </li>
1.7 ihickson 1212:
1213: <li>
1.68 ihickson 1214:
1.115 ihickson 1215: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1216: created, as follows.</p>
1217:
1218: <p>Create a new <span>script execution environment</span>
1219: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1220:
1.68 ihickson 1221: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1222: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1223: entry-points</span>; set the <i>initial code entry-point</i> to
1224: the entry-point for any executable code to be immediately run.</p>
1225:
1226: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1227:
1228: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1229:
1.83 ihickson 1230: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1231: UTF-8. (This is just used for encoding non-ASCII characters in the
1232: query component of URLs.)</p>
1.68 ihickson 1233:
1234: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1235:
1.81 ihickson 1236: </li>
1.4 ihickson 1237:
1238: <li>
1.81 ihickson 1239:
1240: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1241: worker such that no sooner than it stops being either a
1242: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1243: worker</a>, and no later than it stops being a
1244: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1245: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1246: to true<!-- v2-onclose and <span title="queue a task">a task is
1.179 ihickson 1247: queued</span> to <span>fire a simple event</span> named <code
1.123 ihickson 1248: title="event-close">close</code> at <var title="">worker global
1249: scope</var>-->.</p>
1.81 ihickson 1250:
1251: </li>
1.9 ihickson 1252:
1253: <li>
1.7 ihickson 1254:
1.81 ihickson 1255: <p><strong>Suspending workers</strong>: Start monitoring the
1256: worker, such that whenever <var title="">worker global
1.115 ihickson 1257: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1258: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1259: agent suspends execution of script in that worker until such time
1.115 ihickson 1260: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1261: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1262: worker</a>.</p>
1.4 ihickson 1263:
1.81 ihickson 1264: </li>
1.68 ihickson 1265:
1266: <li>
1.4 ihickson 1267:
1.81 ihickson 1268: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1269: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1270: entry-point</i>, and let that run until it either returns, fails
1271: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1272: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1273: algorithms defined below.</p>
1274:
1.149 ihickson 1275: <!-- v2-onclose
1276: <p class="note">If the script gets aborted by the "<span>kill a
1277: worker</span>" algorithm, then that same algorithm will cause
1.115 ihickson 1278: there to only be a single <span title="concept-task">task</span>
1.81 ihickson 1279: in the <span>event loop</span> at the next step, namely the task
1.115 ihickson 1280: for the <code title="message-close">close</code> event. The
1.149 ihickson 1281: "<span>terminate a worker</span>" algorithm removes all the
1.81 ihickson 1282: events.</p>
1.149 ihickson 1283: -->
1.4 ihickson 1284:
1.81 ihickson 1285: </li>
1.4 ihickson 1286:
1.95 ihickson 1287: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1288: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1289: a dedicated worker), then enable the <span>port message
1290: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1291:
1.4 ihickson 1292: <li>
1.68 ihickson 1293:
1.115 ihickson 1294: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1295: 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 1296: to true.</p>
1.43 ihickson 1297:
1.81 ihickson 1298: </li>
1.4 ihickson 1299:
1300: <li>
1301:
1.81 ihickson 1302: <p>Run the oldest task on one of the <span>event loop</span>'s
1303: <span title="task queue">task queues</span>, if any. The user
1304: agent may pick any <span>task queue</span>.</p>
1305:
1.115 ihickson 1306: <p class="note">The handling of events or the execution of
1307: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1308: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1309: defined below.</p>
1.8 ihickson 1310:
1.81 ihickson 1311: </li>
1.4 ihickson 1312:
1313: <li>
1314:
1.81 ihickson 1315: <p>Remove the task run in the previous step, if any, from its
1316: <span>task queue</span>.</p>
1.4 ihickson 1317:
1.81 ihickson 1318: </li>
1.4 ihickson 1319:
1320: <li>
1.8 ihickson 1321:
1.81 ihickson 1322: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1323: <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 1324: to false, then jump back to the step above labeled <i>event
1325: loop</i>.</p>
1.8 ihickson 1326:
1.81 ihickson 1327: </li>
1.8 ihickson 1328:
1329: <li>
1.71 ihickson 1330:
1.123 ihickson 1331: <p>If there are any outstanding transactions that have callbacks
1332: that involve <span title="concept-script">scripts</span> whose
1333: <span title="script's global object">global object</span> is the
1334: <var title="">worker global scope</var>, roll them back (without
1335: invoking any of the callbacks).</p>
1.50 ihickson 1336:
1.123 ihickson 1337: </li>
1338:
1339: <li>
1340:
1341: <p>Empty the <var title="">worker global scope</var>'s <span>list
1342: of active timeouts</span> and its <span>list of active
1343: intervals</span>.</p>
1.50 ihickson 1344:
1.81 ihickson 1345: </li>
1.50 ihickson 1346:
1.123 ihickson 1347: <!-- v2-onclose
1.81 ihickson 1348: <li>
1.50 ihickson 1349:
1.123 ihickson 1350: <p>For each <code>Worker</code> or <code>SharedWorker</code>
1.81 ihickson 1351: object associated with <var title="">worker global scope</var>,
1352: <span>queue a task</span> to <span>fire a simple event</span>
1.179 ihickson 1353: named <code title="event-close">close</code> at that object.</p>
1.5 ihickson 1354:
1.81 ihickson 1355: </li>
1.123 ihickson 1356: -->
1.155 ihickson 1357: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1358: run the following steps in parallel with the worker's main loop (the
1.155 ihickson 1359: "<a href="#run-a-worker">run a worker</a>" processing model defined above):<ol><!-- v2-onclose
1.123 ihickson 1360: <li><p>If the worker's <code>WorkerGlobalScope</code> object's
1361: <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
1.81 ihickson 1362: false, <span>queue a task</span> to <span>fire a simple
1.179 ihickson 1363: event</span> named <code title="event-close">close</code> at the
1.123 ihickson 1364: worker's <code>WorkerGlobalScope</code> object.</p></li>
1.155 ihickson 1365: --><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 1366: true.</li>
1367:
1.123 ihickson 1368: <!-- v2-onclose
1369: <li><p>Wait a user-agent-defined amount of time. If the "<span>run
1370: a worker</span>" processing model defined above immediately starts
1371: running event listeners registered for the <code
1372: title="event-close">close</code> event, this time should not be
1373: zero — the idea is that the <code
1374: title="event-close">close</code> event can be used to clean up
1375: when shutting down unexpectedly.</p></li>
1376: -->
1.81 ihickson 1377:
1.115 ihickson 1378: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1379: queued in the <span>event loop</span>'s <span title="task
1.123 ihickson 1380: queue">task queues</span><!-- v2-onclose other than the <code
1381: title="event-close">close</code> event that this algorithm just
1382: added-->, discard them without processing them.</li>
1.81 ihickson 1383:
1.123 ihickson 1384: <!-- v2-onclose
1.115 ihickson 1385: <li><p>If the <code title="event-close">close</code> event that
1.81 ihickson 1386: this algorithm just queued hasn't yet been dispatched, then abort
1.123 ihickson 1387: the script currently running in the worker.</p></li>
1388: -->
1.81 ihickson 1389:
1390: <li><p>Wait a user-agent-defined amount of time.</li>
1391:
1.123 ihickson 1392: <li><p>Abort the script currently running in the worker<!--
1393: v2-onclose (if any script is running, then it will be a handler for
1394: the <code title="event-close">close</code> event)-->.</li>
1.81 ihickson 1395:
1.155 ihickson 1396: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1397: processing model on a worker at any time, e.g. in response to user
1398: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1399: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1400: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.155 ihickson 1401: 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 1402: the following steps in parallel with the worker's main loop (the
1.155 ihickson 1403: "<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 1404: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1405: true.</li>
1406:
1.115 ihickson 1407: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1408: queued in the <span>event loop</span>'s <span title="task
1409: queue">task queues</span>, discard them without processing
1410: them.</li>
1411:
1412: <li><p>Abort the script currently running in the worker.</li>
1413:
1.115 ihickson 1414: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1415: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1416: worker is a dedicated worker), then empty the <span>port message
1417: queue</span> of the port that the worker's implicit port is
1418: entangled with.</li>
1419:
1.155 ihickson 1420: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.186 ihickson 1421: <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 1422: worker's scripts, if the error did not occur while handling a
1423: previous script error, the user agent must <span>report the
1424: 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 1425: attribute.
1426:
1427: <a href="#refsHTML5">[HTML5]</a>
1428:
1429: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1430: the error occurred while handling a previous script error, the error
1.205 ihickson 1431: should be reported to the user.
1432:
1433: <a href="#refsHTML5">[HTML5]</a>
1434:
1435: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1436: the error occurred while handling a previous script error, the user
1.123 ihickson 1437: agent must <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1438: event</a> at the <code><a href="#worker">Worker</a></code> object associated with the
1.155 ihickson 1439: 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 1440: a <code><a href="#worker">Worker</a></code> object, it must dispatch an event that uses
1441: 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 1442: 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 1443: appropriately. The default action of this event depends on whether
1.115 ihickson 1444: the <code><a href="#worker">Worker</a></code> object is itself in a worker. If it is, and
1.81 ihickson 1445: that worker is also a dedicated worker, then the user agent must
1.118 ihickson 1446: again <span>queue a task</span> to <a href="#fire-a-worker-error-event">fire a worker error
1447: event</a> at the <code><a href="#worker">Worker</a></code> object associated with
1448: <em>that</em> worker. Otherwise, then the error should be reported
1.155 ihickson 1449: to the user.<p>The <span>task source</span> for the tasks mentioned above is the
1450: <span>DOM manipulation task source</span>.<hr><pre class="idl">interface <dfn id="errorevent">ErrorEvent</dfn> : Event {
1.147 ihickson 1451: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1452: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1453: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.147 ihickson 1454: 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 1455: };</pre><p>The <dfn id="dom-errorevent-initerrorevent" title="dom-ErrorEvent-initErrorEvent"><code>initErrorEvent()</code></dfn>
1.190 ihickson 1456: method must initialize the event in a manner analogous to the
1457: 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 1458: attribute represents the error message.<p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.81 ihickson 1459: attribute represents the <span>absolute URL</span> of the script in
1.155 ihickson 1460: which the error originally occurred.<p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.132 ihickson 1461: attribute represents the line number where the error occurred in the
1.186 ihickson 1462: script.<h3 id="creating-workers"><span class="secno">4.7 </span>Creating workers</h3><h4 id="the-abstractworker-abstract-interface"><span class="secno">4.7.1 </span>The <code><a href="#abstractworker">AbstractWorker</a></code> abstract interface</h4><pre class="idl">interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.144 ihickson 1463: attribute <span>Function</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1464: <!-- v2-onclose attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
1.172 ihickson 1465: };
1.177 ihickson 1466: <a href="#abstractworker">AbstractWorker</a> implements <span>EventTarget</span>;</pre><p>The following are the <span>event handlers</span> (and their
1467: corresponding <span title="event handler event type">event handler
1468: event types</span>) that must be supported, as IDL attributes, by
1469: 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 1470: <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 1471: <!-- v2-onclose <tr><td><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> <td> <code title="event-close">close</code> -->
1.186 ihickson 1472: </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 1473: interface <dfn id="worker">Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1474: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1475:
1.174 ihickson 1476: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(in any message, in optional <span>MessagePortArray</span> ports);<!--
1.81 ihickson 1477: <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
1.144 ihickson 1478: attribute <span>Function</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.155 ihickson 1479: };</pre><p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1480: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1481: algorithm to be run on the worker with with the object is
1.155 ihickson 1482: associated.<p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.81 ihickson 1483: <code>MessagePort</code> associated with them. This port is part of
1484: a channel that is set up when the worker is created, but it is not
1485: exposed. This object must never be garbage collected before the
1.155 ihickson 1486: <code><a href="#worker">Worker</a></code> object.<p>All messages received by that port must immediately be retargeted
1487: 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 1488: and <dfn
1489: title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
1.115 ihickson 1490: method<!--s (startConversation)--> on <code><a href="#worker">Worker</a></code> objects
1.81 ihickson 1491: must act as if, when invoked, it<!--/they (startConversation)-->
1492: immediately invoked the method of the same name on the port, with
1.177 ihickson 1493: the same arguments, and returned the same return value.<p>The following are the <span>event handlers</span> (and their
1494: corresponding <span title="event handler event type">event handler
1495: event types</span>) that must be supported, as IDL attributes, by
1496: 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 1497: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1498: </table><hr><p>When the <dfn id="dom-worker" title="dom-Worker"><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
1499: user agent must run the following steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument relative to the <span>first
1.133 ihickson 1500: script</span>'s <span title="script's base URL">base URL</span>,
1501: when the method is invoked.</li>
1.9 ihickson 1502:
1.81 ihickson 1503: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1504: exception.</li>
1.9 ihickson 1505:
1.167 ihickson 1506: <li>
1507:
1508: <p>If the <span>origin</span> of the resulting <span>absolute
1509: URL</span> is not the <span title="same origin">same</span> as the
1.176 ihickson 1510: origin of the <span>first script</span>, then throw a
1.182 ihickson 1511: <code>SECURITY_ERR</code> exception.</p>
1.167 ihickson 1512:
1513: <p class="note">Thus, scripts must be external files with the same
1514: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1515: URL, and a <code>http:</code> page couldn't start workers using
1516: scripts with <code>http:</code> URLs.</p>
1517:
1518: </li>
1.9 ihickson 1519:
1.185 ihickson 1520: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1521: object. Let <var title="">worker global scope</var> be this new
1522: object.</li>
1.9 ihickson 1523:
1.115 ihickson 1524: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1525: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1526:
1.185 ihickson 1527: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1528: owned by the <span title="script's global object">global
1529: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1530: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1531: port</var>.</li>
1.9 ihickson 1532:
1.81 ihickson 1533: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1534:
1.185 ihickson 1535: <li><p><span>Create a new <code>MessagePort</code> object</span>
1536: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1537:
1.81 ihickson 1538: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 1539:
1.81 ihickson 1540: <li><p><span>Entangle</span> <var title="">outside port</var> and
1541: <var title="">inside port</var>.</li>
1.50 ihickson 1542:
1.81 ihickson 1543: <li><p>Return <var title="">worker</var>, and run the following
1544: steps asynchronously.</li>
1.50 ihickson 1545:
1.204 ihickson 1546: <!-- (this is done by the "run a worker" algorithm)
1.126 ihickson 1547: <li><p>Enable <var title="">inside port</var>'s <span>port message
1.204 ihickson 1548: queue</span>.</p></li>
1549: -->
1.50 ihickson 1550:
1.126 ihickson 1551: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 1552: queue</span>.</li>
1.50 ihickson 1553:
1554: <li>
1.51 ihickson 1555:
1.123 ihickson 1556: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1557: <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 1558: constructor.</p>
1559:
1560: </li>
1561:
1562: <li>
1563:
1564: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1565: <var title="">worker global scope</var>'s list of <span>the
1566: worker's <code>Document</code>s</span></a> the
1567: <code>Document</code> objects in <var title="">docs</var>.</p>
1568:
1569: </li>
1570:
1571: <li>
1572:
1.192 ihickson 1573: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1574: of the <span title="concept-script">script</span> that invoked the
1575: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
1576: are creating a nested worker), add <var title="">worker global
1577: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 1578: <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 1579: constructor.</p>
1580:
1581: </li>
1582:
1583: <li>
1584:
1.115 ihickson 1585: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 1586: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 1587: script that invoked the method as the <var title="">owner browsing
1.176 ihickson 1588: context</var>, with the <span>origin</span> of the <span>first
1589: script</span> as the <var title="">owner origin</var>, and with
1590: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 1591:
1.81 ihickson 1592: </li>
1.4 ihickson 1593:
1.155 ihickson 1594: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1595: object</span> is either a <code>Window</code> object or an object
1.186 ihickson 1596: 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 1597: interface <dfn id="sharedworker">SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
1598: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.155 ihickson 1599: };</pre><p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 1600: attribute must return the value it was assigned by the object's
1601: constructor. It represents the <code>MessagePort</code> for
1.155 ihickson 1602: 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 1603: constructor is invoked, the user agent must run the following
1.155 ihickson 1604: steps:<ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 1605:
1606: <li><p>If this fails, throw a <code>SYNTAX_ERR</code>
1607: exception.</li>
1608:
1.159 ihickson 1609: <li><p>Otherwise, let <var title="">scriptURL</var> be the
1610: resulting <span>absolute URL</span>.</li>
1611:
1612: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 1613: argument, or the empty string if the second argument was
1614: omitted.</li>
1.159 ihickson 1615:
1.167 ihickson 1616: <li>
1617:
1618: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
1619: not the <span title="same origin">same</span> as the origin of the
1.182 ihickson 1620: <span>first script</span>, then throw a <code>SECURITY_ERR</code>
1621: exception.</p>
1.167 ihickson 1622:
1623: <p class="note">Thus, scripts must be external files with the same
1624: scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
1625: URL, and a <code>http:</code> page couldn't start workers using
1626: scripts with <code>http:</code> URLs.</p>
1627:
1628: </li>
1.9 ihickson 1629:
1630: <li>
1631:
1.123 ihickson 1632: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 1633: <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 1634: constructor.</p>
1635:
1636: </li>
1637:
1638: <li>
1639:
1.50 ihickson 1640: <p>Execute the following substeps atomically:</p>
1.9 ihickson 1641:
1.155 ihickson 1642: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 1643: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1644: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 1645:
1.185 ihickson 1646: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.192 ihickson 1647: owned by the <span title="script's global object">global
1648: object</span> of the script that invoked the method. Let this be
1.123 ihickson 1649: the <var title="">outside port</var>.</li>
1.81 ihickson 1650:
1.115 ihickson 1651: <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 1652:
1.164 ihickson 1653: <li><p>Let <var title="">worker global scope</var> be
1654: null.</li>
1655:
1656: <li><p>If <var title="">name</var> is not the empty string and
1657: there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose
1658: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1659: is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
1660: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1661: represents an <span>absolute URL</span> with the <span>same
1662: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1663: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1664:
1665: <li><p>Otherwise, if <var title="">name</var> is the empty string
1666: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
1667: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1668: flag is false, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1669: is exactly equal to <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
1670: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</li>
1671:
1.9 ihickson 1672: <li>
1673:
1.164 ihickson 1674: <p>If <var title="">worker global scope</var> is not null, then
1675: run these steps:</p>
1.81 ihickson 1676:
1.164 ihickson 1677: <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 1678: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 1679: exactly equal to <var title="">scriptURL</var>, then throw a
1680: <code>URL_MISMATCH_ERR</code> exception and abort all these
1681: steps.</li>
1.81 ihickson 1682:
1683: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1684:
1.185 ihickson 1685: <li><p><span>Create a new <code>MessagePort</code>
1686: object</span> owned by <var title="">worker global
1687: scope</var>. Let this be the <var title="">inside
1688: port</var>.</li>
1.81 ihickson 1689:
1690: <li><p><span>Entangle</span> <var title="">outside port</var>
1691: and <var title="">inside port</var>.</li>
1692:
1693: <li><p>Return <var title="">worker</var> and perform the next
1694: step asynchronously.</li>
1.9 ihickson 1695:
1.81 ihickson 1696: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 1697: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 1698: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1699: is the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1700: value is an array containing only the newly created port, and
1701: <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</li>
1.43 ihickson 1702:
1.123 ihickson 1703: <li>
1704:
1705: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1706: <var title="">worker global scope</var>'s list of <span>the
1707: worker's <code>Document</code>s</span></a> the
1708: <code>Document</code> objects in <var title="">docs</var>.</p>
1709:
1710: </li>
1711:
1.124 ihickson 1712: <li>
1713:
1.192 ihickson 1714: <p>If the <span title="script's global object">global
1715: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1716: that invoked the constructor is a
1717: <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
1718: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1719: object that is the <span title="script's global object">global
1720: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1721: that invoked the constructor.</p>
1722:
1723: </li>
1724:
1.81 ihickson 1725: <li><p>Abort all these steps.</li>
1.9 ihickson 1726:
1.155 ihickson 1727: </ol></li>
1.9 ihickson 1728:
1.185 ihickson 1729: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1730: object. Let <var title="">worker global scope</var> be this new
1731: object.</li>
1.9 ihickson 1732:
1.81 ihickson 1733: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 1734:
1.115 ihickson 1735: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 1736: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 1737:
1.185 ihickson 1738: <li><p><span>Create a new <code>MessagePort</code> object</span>
1.81 ihickson 1739: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 1740:
1.81 ihickson 1741: <li><p><span>Entangle</span> <var title="">outside port</var> and
1742: <var title="">inside port</var>.</li>
1.9 ihickson 1743:
1.155 ihickson 1744: </ol></li>
1.28 ihickson 1745:
1.123 ihickson 1746: <li><p>Return <var title="">worker</var> and perform the remaining
1747: steps asynchronously.</li>
1.18 ihickson 1748:
1.81 ihickson 1749: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 1750: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 1751: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.118 ihickson 1752: the empty string and has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1753: is an array containing only the newly created port, and <span>queue
1754: a task</span> to dispatch the event at <var title="">worker global
1755: scope</var>.</li>
1.26 ihickson 1756:
1757: <li>
1.46 ihickson 1758:
1.123 ihickson 1759: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
1760: <var title="">worker global scope</var>'s list of <span>the
1761: worker's <code>Document</code>s</span></a> the
1762: <code>Document</code> objects in <var title="">docs</var>.</p>
1763:
1764: </li>
1765:
1766: <li>
1767:
1.192 ihickson 1768: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 1769: of the <span title="concept-script">script</span> that invoked the
1770: 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
1771: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 1772: object that is the <span title="script's global object">global
1773: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 1774: that invoked the constructor.</p>
1775:
1776: </li>
1777:
1778: <li>
1779:
1.159 ihickson 1780: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 1781: with the <span>script's browsing context</span> of the script that
1.159 ihickson 1782: invoked the method as the <var title="">owner browsing
1.176 ihickson 1783: context</var>, with the <span>origin</span> of the <span>first
1784: script</span> as the <var title="">owner origin</var>, and with
1785: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 1786:
1.60 ihickson 1787: </li>
1.81 ihickson 1788:
1.155 ihickson 1789: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 1790: object</span> is either a <code>Window</code> object or an object
1.155 ihickson 1791: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.<p>The <span>task source</span> for the tasks mentioned above is the
1792: <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 1793: interface <dfn id="workerutils">WorkerUtils</dfn> {
1794: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(in DOMString... urls);
1.115 ihickson 1795: readonly attribute <a href="#worker-navigator" title="worker-Navigator">Navigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 1796: };
1.184 ihickson 1797: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;</pre><p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 1798: objects, etc) are not available to workers in this version of this
1.155 ihickson 1799: 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 1800: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.155 ihickson 1801: following steps:<ol><li><p>If there are no arguments, return without doing
1.81 ihickson 1802: anything. Abort these steps.</li>
1803:
1804: <li><p><span title="resolve a url">Resolve</span> each
1805: argument.</li>
1806:
1807: <li><p>If any fail, throw a <code>SYNTAX_ERR</code>
1808: exception.</li>
1809:
1810: <!--
1.67 ihickson 1811: <li><p>If any of the resulting <span title="absolute URL">absolute
1812: URLs</span> have an <span>origin</span> that is not the <span
1813: title="same origin">same</span> as the origin of the script that
1.182 ihickson 1814: invoked the method, then throw a <code>SECURITY_ERR</code>
1815: exception.</p></li>
1.67 ihickson 1816: -->
1.26 ihickson 1817:
1818: <li>
1.81 ihickson 1819:
1.45 ihickson 1820: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 1821: resulting <span title="absolute URL">absolute URLs</span>, from
1.176 ihickson 1822: the <span>first script</span>'s <span>origin</span>.</p> <!-- not
1823: http-origin privacy sensitive -->
1.81 ihickson 1824:
1825: </li>
1.26 ihickson 1826:
1827: <li>
1828:
1.81 ihickson 1829: <p>For each argument in turn, in the order given, starting with
1830: the first one, run these substeps:</p>
1.26 ihickson 1831:
1.155 ihickson 1832: <ol><li>
1.26 ihickson 1833:
1.81 ihickson 1834: <p>Wait for the fetching attempt for the corresponding resource
1835: to complete.</p>
1.60 ihickson 1836:
1.81 ihickson 1837: <p>If the fetching attempt failed, throw a
1838: <code>NETWORK_ERR</code> exception and abort all these
1839: steps.</p>
1.45 ihickson 1840:
1.186 ihickson 1841: <p>If the attempt succeeds, then convert the script resource to
1842: Unicode by assuming it was encoded as UTF-8, to obtain its <var title="">source</var>.</p>
1.85 ihickson 1843:
1844: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 1845:
1.115 ihickson 1846: <p class="note">As with the worker's script, the script here is
1.81 ihickson 1847: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 1848: type.</p>
1.61 ihickson 1849:
1.81 ihickson 1850: </li>
1.26 ihickson 1851:
1.81 ihickson 1852: <li>
1.26 ihickson 1853:
1.81 ihickson 1854: <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 1855: same global object, browsing context, URL character encoding,
1856: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 1857: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 1858:
1.115 ihickson 1859: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 1860: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 1861: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
1862: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 1863:
1.199 ihickson 1864: <p>If it failed to parse, then throw an ECMAScript
1865: <code>SyntaxError</code> exception and abort all these
1866: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 1867:
1.81 ihickson 1868: <p>If an exception was raised or if the script was prematurely
1869: aborted, then abort all these steps, letting the exception or
1870: aborting continue to be processed by the script that called the
1.115 ihickson 1871: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 1872: method.</p>
1873:
1.115 ihickson 1874: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 1875: worker</a>" algorithms abort the script then abort all these
1876: steps.</p>
1877:
1878: </li>
1879:
1.155 ihickson 1880: </ol></li>
1.152 ihickson 1881:
1.155 ihickson 1882: </ol><h3 id="the-navigator-object"><span class="secno">5.2 </span>The <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> object</h3><p>The <dfn id="dom-worker-navigator" title="dom-worker-navigator"><code>navigator</code></dfn> attribute
1.115 ihickson 1883: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1884: the <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> interface, which
1.93 ihickson 1885: represents the identity and state of the user agent (the
1.155 ihickson 1886: client):<pre class="idl">interface <dfn id="worker-navigator" title="worker-Navigator">Navigator</dfn> {};
1.150 ihickson 1887: <a href="#worker-navigator" title="worker-Navigator">Navigator</a> implements <span>NavigatorID</span>;
1.155 ihickson 1888: <a href="#worker-navigator" title="worker-Navigator">Navigator</a> implements <span>NavigatorOnLine</span>;</pre><p>Objects implementing the <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code> interface also implement
1.150 ihickson 1889: the <code>NavigatorID</code> and <code>NavigatorOnLine</code>
1.205 ihickson 1890: interfaces.
1891:
1892: <a href="#refsHTML5">[HTML5]</a>
1893:
1894: <p class="note">The <code title="worker-Navigator"><a href="#worker-navigator">Navigator</a></code>
1.93 ihickson 1895: interface defined in this specification is different than the one
1.155 ihickson 1896: defined in the HTML specification.<h3 id="apis-defined-in-other-specifications"><span class="secno">5.3 </span>APIs defined in other specifications</h3><p>The <code title="dom-opendatabase">openDatabase()</code> and
1.115 ihickson 1897: <code title="dom-opendatabase-sync">openDatabaseSync()</code>
1.200 ihickson 1898: 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 1899: the global scope of scripts whose <span>script's global
1900: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.155 ihickson 1901: the following:<ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 1902: constructors defined by the XMLHttpRequest specifications, except
1903: that the <span>document response entity body</span> must always be
1.160 ihickson 1904: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
1905: <span>script's base URL</span>; the
1906: <span><code>XMLHttpRequest</code> origin</span> is the script's
1907: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 1908:
1.205 ihickson 1909: <li><p>The interface objects and constructors defined by this
1910: specification.</li>
1.119 ihickson 1911:
1.205 ihickson 1912: <li><p>Constructors defined by specifications that explicitly say
1913: that they should be visible when the <span>script's global
1914: object</span> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>, a
1915: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>, or an object implementing the
1916: <code><a href="#workerutils">WorkerUtils</a></code> interface; the interfaces of any objects
1917: with such constructors; and the interfaces of any objects made
1918: accessible through APIs exposed by those constructors or made
1919: accessible through interfaces to be implemented by any objects that
1920: are themselves accessible to scripts whose <span>script's global
1921: object</span> implements the <code><a href="#workerutils">WorkerUtils</a></code>
1922: interface.</li>
1923:
1924: </ul><p class="note">These requirements do not override the requirements
1925: defined by the Web IDL specification, in particular concerning the
1926: 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 1927: readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
1928: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
1929: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
1930: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
1931: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
1932: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
1933: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
1934: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.155 ihickson 1935: };</pre><p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
1936: URL</span> set at its creation.<p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 1937: attribute must return the <span>absolute URL</span> that the object
1.155 ihickson 1938: represents.<p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 1939: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 1940: <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>,
1941: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
1942: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
1943: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>. These must
1.163 ihickson 1944: follow the rules given for URL decomposition IDL attributes, with the
1.115 ihickson 1945: <span title="concept-uda-input">input</span> being the
1.81 ihickson 1946: <span>absolute URL</span> that the object represents (same as the
1.115 ihickson 1947: <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and
1948: the <span title="concept-uda-setter">common setter action</span>
1.205 ihickson 1949: being a no-op, since the attributes are defined to be readonly.
1950:
1951: <a href="#refsHTML5">[HTML5]</a>
1952:
1953: </p><!--START vCard--><!--START vEvent--><h2 class="no-num" id="references">References</h2><!--REFS--><!--END vCard--><!--END vEvent--><p>All references are normative unless marked "Non-normative".</p><!--START vCard--><!--START vEvent--><dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.153 ihickson 1954: <dd><cite><a href="http://www.w3.org/TR/DOM-Level-3-Core/">Document
1955: Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
1956: Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
1957: S. Byrnes. W3C, April 2004.</dd>
1958: <!--
1959: <dd><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
1960: DOM Core</a></cite>, S. Pieters. W3C, June 2009.</dd>
1961: -->
1962:
1.152 ihickson 1963: <dt id="refsDOMEVENTS">[DOMEVENTS]</dt>
1964: <!--
1965: <dd><cite><a
1966: href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
1967: Model (DOM) Level 3 Events Specification</a></cite>,
1968: B. Höhrmann, P. Le Hegaret, T. Pixley. W3C, December
1969: 2007.</dd>
1970: -->
1971: <dd><cite><a href="http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html">Document
1972: Object Model (DOM) Level 3 Events Specification</a></cite>,
1973: D. Schepers. W3C, July 2009.</dd>
1974:
1975: <dt id="refsECMA262">[ECMA262]</dt>
1976: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1977: Language Specification</a></cite>. ECMA, December 1999.</dd>
1978:
1979: <dt id="refsHTML5">[HTML5]</dt>
1980: <!--
1.161 ihickson 1981: <dd><cite><a href="http://www.w3.org/TR/html5/">HTML5</a></cite>,
1.152 ihickson 1982: I. Hickson, D. Hyatt. W3C, April 2009.</dd>
1.161 ihickson 1983: <dd><cite><a
1984: href="http://www.w3.org/html/wg/html5/">HTML5</a></cite>,
1985: I. Hickson, D. Hyatt. W3C, August 2009.</dd>
1.152 ihickson 1986: -->
1.161 ihickson 1987: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML5</a></cite>,
1988: I. Hickson. WHATWG, August 2009.</dd>
1.152 ihickson 1989:
1.154 ihickson 1990: <dt id="refsRFC2119">[RFC2119]</dt>
1991: <dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
1992: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF, March
1993: 1997.</dd>
1994:
1.200 ihickson 1995: <dt id="refsWEBSQL">[WEBSQL]</dt>
1996: <dd><cite><a href="http://dev.w3.org/html5/webdatabase/">Web SQL
1997: Database</a></cite>, I. Hickson. W3C, July 2009.</dd>
1.152 ihickson 1998:
1.154 ihickson 1999: <dt id="refsWEBIDL">[WEBIDL]</dt>
2000: <!--
2001: <dd><cite><a href="http://www.w3.org/TR/WebIDL/">Web
2002: IDL</a></cite>, C. McCormack. W3C, December 2008.</dd>
2003: -->
2004: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
2005: IDL</a></cite>, C. McCormack. W3C, July 2009.</dd>
2006:
1.152 ihickson 2007: <dt id="refsXHR">[XHR]</dt>
2008: <!--
2009: <dd><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
2010: Object</a></cite>, A. van Kesteren. W3C, April
2011: 2008.</dd>
2012: -->
1.160 ihickson 2013: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.152 ihickson 2014: A. van Kesteren. W3C, June 2009.</dd>
2015:
1.178 ihickson 2016: </dl><!--END vCard--><!--END vEvent--><h2 class="no-num" id="acknowledgements">Acknowledgements</h2><!-- ACKS --><p>Thanks to
1.81 ihickson 2017:
2018: Aaron Boodman,
1.155 ihickson 2019: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2020: Anne van Kesteren,
2021: Ben Turner,
2022: Dmitry Titov,
1.96 ihickson 2023: Drew Wilson,
1.97 ihickson 2024: Jeremy Orlow,
1.81 ihickson 2025: Jonas Sicking,
2026: Justin James,
2027: Kevin Hakanson,
2028: Maciej Stachowiak,
2029: Michael Nordman,
2030: Mike Smith,
2031:
2032: and
2033:
2034: Philip Taylor
2035:
1.155 ihickson 2036: for their useful and substantial comments.<p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2037: technology and whose experience has been a huge influence on this
1.155 ihickson 2038: specification.
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