Annotation of html5/workers/Overview.html, revision 1.42
1.1 ihickson 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
2: <!-- when publishing, change bits marked ZZZ -->
3:
4: <html lang=en-US-x-Hixie>
5: <head>
6: <title>Web Workers</title>
7: <link href="http://www.w3.org/StyleSheets/TR/%57%33%43-ED" rel=stylesheet
8: type="text/css">
9: <!-- ZZZ ED vs WD -->
10:
11: <body>
12: <div class=head>
13: <p><a href="http://www.w3.org/"><img alt=W3C height=48
14: src="http://www.w3.org/Icons/w3c_home" width=72></a></p>
15:
16: <h1 id=web-workers>Web Workers</h1>
17:
18: <h2 class="no-num no-toc" id=an-accompaniment>An accompaniment
19: specification for HTML5</h2>
20:
21: <h2 class="no-num no-toc" id=editors><!-- "W3C Working Draft" --> Editor's
1.42 ! ihickson 22: Draft <!--ZZZ--> 8 August 2008</h2>
1.1 ihickson 23:
24: <dl><!-- ZZZ: update the month/day
25: <dt>This Version:</dt>
26: <dd><a href="http://www.w3.org/TR/2008/WD-workers-20080101/">http://www.w3.org/TR/2008/WD-workers-20080101/</a></dd>
1.2 ihickson 27: <dt>Latest Published Version:</dt>
28: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.1 ihickson 29: :ZZZ -->
30:
31: <dt>Latest Editor's Draft:
32:
33: <dd><a
34: href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.2 ihickson 35: <!-- ZZZ: add the new version after it has shipped
36: <dt>Previous Versions:</dt>
37: <dd><a href="http://www.w3.org/TR/2008/WD-workers-20080101/">http://www.w3.org/TR/2008/WD-workers-20080101/</a>
38: :ZZZ -->
1.1 ihickson 39:
40: <dt>Editors:
41:
42: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.
43: </dl>
44:
45: <p class=copyright><a
46: href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
47: © 2008 <a href="http://www.w3.org/"><abbr title="World Wide Web
48: Consortium">W3C</abbr></a><sup>®</sup> (<a
49: href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
50: Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr
51: title="European Research Consortium for Informatics and
52: Mathematics">ERCIM</abbr></a>, <a
53: href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
54: href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
55: <a
56: href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
57: and <a
58: href="http://www.w3.org/Consortium/Legal/copyright-documents">document
59: use</a> rules apply.</p>
60: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
61:
62: <p class="alt copyright">The <a
63: href="http://www.whatwg.org/specs/web-workers/current-work/">WHATWG
64: version</a> of this specification is available under a more permissive
65: license.</p>
66: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
67: </div>
68:
69: <hr>
70:
71: <h2 class="no-num no-toc" id=abstract>Abstract</h2>
72:
73: <p>This specification defines an API that allows Web application authors to
74: spawn background workers running scripts in parallel to their main page.
75: This allows for thread-like operation with message-passing as the
76: coordination mechanism.
77:
78: <h2 class="no-num no-toc" id=status>Status of this document</h2>
79: <!-- intro boilerplate (required) -->
80:
81: <p><em>This section describes the status of this document at the time of
82: its publication. Other documents may supersede this document. A list of
83: current W3C publications and the most recently formally published revision
84: of this technical report can be found in the <a
85: href="http://www.w3.org/TR/">W3C technical reports index</a> at
86: http://www.w3.org/TR/.</em></p>
87: <!-- where to send feedback (required) -->
88:
89: <p>If you wish to make comments regarding this document, please send them
90: to <a
91: href="mailto:public-html-comments@w3.org">public-html-comments@w3.org</a>
92: (<a
93: href="mailto:public-html-comments-request@w3.org?subject=subscribe">subscribe</a>,
94: <a
95: href="http://lists.w3.org/Archives/Public/public-html-comments/">archives</a>)
96: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
97: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a
98: href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
99: <a
100: href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
101: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
102: All feedback is welcome.</p>
103: <!-- stability (required) -->
104:
105: <p>Implementors should be aware that this specification is not stable.
106: <strong>Implementors who are not taking part in the discussions are likely
107: to find the specification changing out from under them in incompatible
108: ways.</strong> Vendors interested in implementing this specification
109: before it eventually reaches the Candidate Recommendation stage should
110: join the aforementioned mailing lists and take part in the discussions.</p>
111: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
112: <!-- version history or list of changes (required) -->
113:
114: <p>The latest stable version of the editor's draft of this specification is
115: always available on <a
116: href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
117: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG
118: Subversion repository</a>. The latest editor's working copy (which may
119: contain unfinished text in the process of being prepared) is available <a
120: href="http://www.whatwg.org/specs/web-workers/current-work/">on the WHATWG
121: site</a>. Detailed change history can be obtained from the following
122: locations:</p>
123: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
124: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
125:
126: <ul>
127: <li>Twitter messages (non-editorial changes only): <a
128: href="http://twitter.com/WHATWG">http://twitter.com/WHATWG</a>
129:
130: <li>Interactive Web interface: <a
131: href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a>
132:
133: <li>Commit-Watchers mailing list: <a
134: href="http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org">http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a>
135:
136: <li>Subversion interface: <a
137: href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a>
138:
139: <li>CVS log: <a
140: href="http://dev.w3.org/cvsweb/html5/workers/Overview.html">http://dev.w3.org/cvsweb/html5/workers/Overview.html</a>
141: </ul>
142: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
143: <!-- status of document, group responsible (required) -->
144:
145: <p>The W3C <a href="http://www.w3.org/html/wg/">HTML Working Group</a> is
146: the W3C working group responsible for this specification's progress along
1.42 ! ihickson 147: the W3C Recommendation track. <!--ZZZ:--> This specification is the 8
1.25 ihickson 148: August 2008 <!--ZZZ "Working Draft"-->Editor's Draft. <!--:ZZZ--></p>
1.1 ihickson 149: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
150: <!-- relationship to other work (required) -->
151:
152: <p>This specification is also being produced by the <a
153: href="http://www.whatwg.org/">WHATWG</a>. The two specifications are
154: identical from the table of contents onwards.</p>
155: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
156: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
157: <!-- context and rationale (required) -->
158:
159: <p>This specification is intended to specify a part of the Web platform
160: closely related to HTML5. It is defined in a separate document primarily
161: to ease the cognitive load on reviewers.</p>
162: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
163: <!-- required patent boilerplate -->
164:
165: <p>This document was produced by a group operating under the <a
166: href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
167: 2004 W3C Patent Policy</a>. W3C maintains a <a
168: href="http://www.w3.org/2004/01/pp-impl/40318/status"
169: rel=disclosure>public list of any patent disclosures</a> made in
170: connection with the deliverables of the group; that page also includes
171: instructions for disclosing a patent. An individual who has actual
172: knowledge of a patent which the individual believes contains <a
173: href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
174: Claim(s)</a> must disclose the information in accordance with <a
175: href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
176: 6 of the W3C Patent Policy</a>.
177:
178: <h2 class="no-num no-toc" id=contents>Table of contents</h2>
179: <!--begin-toc-->
180:
181: <ul class=toc>
182: <li><a href="#introduction"><span class=secno>1. </span>Introduction</a>
183: <ul class=toc>
1.4 ihickson 184: <li><a href="#tutorial"><span class=secno>1.1 </span>Tutorial</a>
1.29 ihickson 185: <ul class=toc>
186: <li><a href="#a-background"><span class=secno>1.1.1 </span>A
1.32 ihickson 187: background number-crunching worker</a>
1.31 ihickson 188:
189: <li><a href="#a-worker"><span class=secno>1.1.2 </span>A worker for
190: updating a client-side database</a>
1.33 ihickson 191:
192: <li><a href="#worker"><span class=secno>1.1.3 </span>Worker used for
193: backgroud I/O</a>
1.34 ihickson 194:
195: <li><a href="#shared"><span class=secno>1.1.4 </span>Shared
196: workers</a>
197:
1.40 ihickson 198: <li><a href="#delegation"><span class=secno>1.1.5
199: </span>Delegation</a>
200:
201: <li><a href="#granting"><span class=secno>1.1.6 </span>Granting
1.34 ihickson 202: capabilities</a>
1.29 ihickson 203: </ul>
1.1 ihickson 204:
1.22 ihickson 205: <li><a href="#conformance"><span class=secno>1.2 </span>Conformance
1.1 ihickson 206: requirements</a>
207: <ul class=toc>
1.22 ihickson 208: <li><a href="#dependencies"><span class=secno>1.2.1
1.1 ihickson 209: </span>Dependencies</a>
210: </ul>
211:
1.22 ihickson 212: <li><a href="#terminology"><span class=secno>1.3 </span>Terminology</a>
1.4 ihickson 213: </ul>
214:
1.12 ihickson 215: <li><a href="#infrastructure"><span class=secno>2.
216: </span>Infrastructure</a>
1.4 ihickson 217: <ul class=toc>
1.26 ihickson 218: <li><a href="#the-workerglobalscope"><span class=secno>2.1 </span>The
219: <code>WorkerGlobalScope</code> interface</a>
1.4 ihickson 220:
1.15 ihickson 221: <li><a href="#base-urls"><span class=secno>2.2 </span>Base URLs and
222: origins of workers</a>
223:
224: <li><a href="#the-queue"><span class=secno>2.3 </span>The queue of
1.4 ihickson 225: events</a>
226:
1.15 ihickson 227: <li><a href="#the-workers"><span class=secno>2.4 </span>The worker's
1.9 ihickson 228: ports</a>
229:
1.15 ihickson 230: <li><a href="#processing"><span class=secno>2.5 </span>Processing
1.4 ihickson 231: model</a>
1.12 ihickson 232:
1.15 ihickson 233: <li><a href="#creating"><span class=secno>2.6 </span>Creating
1.12 ihickson 234: workers</a>
1.1 ihickson 235: </ul>
236:
1.12 ihickson 237: <li><a href="#apis-available"><span class=secno>3. </span>APIs available
238: to workers</a>
1.26 ihickson 239: <ul class=toc>
240: <li><a href="#importing"><span class=secno>3.1 </span>Importing scripts
241: and libraries</a>
242:
243: <li><a href="#apis-defined"><span class=secno>3.2 </span>APIs defined in
244: other specifications</a>
245:
246: <li><a href="#interface"><span class=secno>3.3 </span>Interface objects
247: and constructors</a>
1.34 ihickson 248:
249: <li><a href="#worker0"><span class=secno>3.4 </span>Worker locations</a>
250:
1.26 ihickson 251: </ul>
1.4 ihickson 252:
1.1 ihickson 253: <li class=no-num><a href="#references">References</a>
254:
255: <li class=no-num><a href="#acknowledgements">Acknowledgements</a>
256: </ul>
257: <!--end-toc-->
258:
259: <hr>
260:
261: <h2 id=introduction><span class=secno>1. </span>Introduction</h2>
262:
1.4 ihickson 263: <h3 id=tutorial><span class=secno>1.1 </span>Tutorial</h3>
1.1 ihickson 264:
265: <p><em>This section is non-normative.</em>
266:
1.29 ihickson 267: <p>There are a variety of uses that workers can be put to. The following
268: subsections show various examples of this use.
269:
270: <h4 id=a-background><span class=secno>1.1.1 </span>A background
1.32 ihickson 271: number-crunching worker</h4>
1.29 ihickson 272:
273: <p><em>This section is non-normative.</em>
274:
275: <p>The simplest use of workers is for performing a computationally
276: expensive task without interrupting the user interface.
277:
1.32 ihickson 278: <p>In this example, the main document spawns a worker to (naïvely)
1.29 ihickson 279: compute prime numbers, and progressively displays the most recently found
280: prime number.
281:
282: <p>The main page is as follows:
283:
284: <pre><!DOCTYPE HTML>
285: <html>
286: <head>
1.40 ihickson 287: <title>Worker example: One-core computation</title>
1.29 ihickson 288: </head>
289: <body>
290: <p>The highest prime number discovered so far is: <output id="result"></output></p>
291: <script>
292: var worker = createWorker('worker.js');
293: worker.onmessage = function (event) {
294: document.getElementById('result').textContent = event.message;
295: };
296: </script>
297: </body>
298: </html></pre>
299:
300: <p>The <code title=dom-WorkerFactory-createWorker><a
301: href="#createworker">createWorker()</a></code> method call creates a
302: worker and returns a <code>MessagePort</code> object, which is used to
303: communicate with the worker. That object's <code
304: title=dom-MessagePort-onmessage>onmessage</code> event handler attribute
305: allows the code to receive messages from the worker.
306:
307: <p>The worker itself is as follows:
308:
309: <pre>var n = 1;
310: search: while (true) {
311: n += 1;
312: for (var i = 2; i <= Math.sqrt(n); i += 1)
313: if (n % i == 0)
314: continue search;
315: // found a prime!
316: port.postMessage(n);
317: }</pre>
318:
319: <p>The bulk of this code is simply an unoptimised search for a prime
320: number. To send a message back to the page, the <code
1.30 ihickson 321: title=dom-WorkerGlobalScope-port><a href="#port">port</a></code> variable
322: (defined automatically when the worker is created) is used to post a
323: message when a prime is found.
1.29 ihickson 324:
325: <p><a href="http://www.whatwg.org/demos/workers/primes/page.html">View this
326: example online</a>.
1.4 ihickson 327:
1.31 ihickson 328: <h4 id=a-worker><span class=secno>1.1.2 </span>A worker for updating a
329: client-side database</h4>
330:
331: <p><em>This section is non-normative.</em>
332:
333: <p>In this example, the main document spawns a worker whose only task is to
334: listen for notifications from the server, and, when appropriate, either
335: add or remove data from the client-side database.
336:
337: <p>Since no communication occurs between the worker and the main page, the
338: main page can start the worker by just doing:
339:
340: <pre><script>
341: createWorker('worker.js');
342: </script></pre>
343:
344: <p>The worker itself is as follows:
345:
346: <pre>var server = new WebSocket('ws://whatwg.org/database');
1.42 ! ihickson 347: var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
1.31 ihickson 348: server.onmessage = function (event) {
349: // data is in the format "command key value"
350: var data = event.message.split(' ');
351: switch (data[0]) {
352: case '+':
353: database.transaction(function(tx) {
354: tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
355: });
356: case '-':
357: database.transaction(function(tx) {
358: tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
359: });
360: }
361: };</pre>
362:
363: <p>This connects to the server using the <code>WebSocket</code> mechanism
364: and opens the local database (which, we presume, has been created
365: earlier). The worker then just listens for messages from the worker and
366: acts on them as appropriate, forever (or until the main page is closed).
367:
368: <p><a
369: href="http://www.whatwg.org/demos/workers/database-updater/page.html">View
370: this example online</a>. (This example will not actually function, since
371: the server does not actually exist and the database is not created by this
372: sample code.)
373:
1.33 ihickson 374: <h4 id=worker><span class=secno>1.1.3 </span>Worker used for backgroud I/O</h4>
375:
376: <p><em>This section is non-normative.</em>
377:
378: <p>In this example, the main document uses two workers, one for fetching
379: stock updates for at regular intervals, and one for fetching performing
380: search queries that the user requests.
381:
382: <p>The main page is as follows:
383:
384: <pre><!DOCTYPE HTML>
385: <html>
386: <head>
387: <title>Worker example: Stock ticker</title>
388: <script>
389: // TICKER
390: var symbol = 'GOOG'; // default symbol to watch
391: var ticker = createWorker('ticker.js');
392: ticker.postMessage(symbol);
393:
394: // SEARCHER
395: var searcher = createWorker('searcher.js');
396: function search(query) {
397: searcher.postMessage(query);
398: }
399:
400: // SYMBOL SELECTION UI
401: function select(newSymbol) {
402: symbol = newSymbol;
403: ticker.postMessage(symbol);
404: }
405: </script>
406: </head>
407: <body>
408: <p><output id="symbol"></output> <output id="value"></output></p>
409: <script>
410: ticker.onmessage = function (event) {
411: var data = event.message.split(' ');
412: document.getElementById('symbol').textContent = data[0];
413: document.getElementById('value').textContent = data[1];
414: };
415: </script>
416: <p><label>Search: <input type="text" oninput="search(this.value)"></label></p>
417: <ul id="results"></ul>
418: <script>
419: searcher.onmessage = function (event) {
420: var data = event.message.split(' ');
421: var results = document.getElementById('results');
422: while (results.hasChildNodes()) // clear previous results
423: results.removeChild(results.firstChild);
424: for (var i = 0; i < data.length; i += 1) {
425: // add a list item with a button for each result
426: var li = document.createElement('li');
427: var button = document.createElement('button');
428: button.value = data[i];
429: button.type = 'button';
430: button.onclick = function () { select(this.value); };
431: button.textContent = data[i];
432: li.appendChild(button);
433: results.appendChild(li);
434: }
435: };
436: </script>
437: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
438: </body>
439: </html></pre>
440:
441: <p>Messages are queued until the <code
442: title=handler-MessagePort-onmessage>onmessage</code> handler is set, so
443: even if it takes a while for the message handler to be attached, no data
444: is lost.
445:
446: <p>The two workers use a common library for performing the actual network
447: calls. This library is as follows:
448:
449: <pre>function get(url) {
450: try {
451: var xhr = new XMLHttpRequest();
452: xhr.open('GET', url, false);
453: xhr.send();
454: return xhr.responseText;
1.34 ihickson 455: } catch (e) {
1.33 ihickson 456: return ''; // turn all errors into empty results
457: }
458: }</pre>
459:
460: <p>The stock updater worker is as follows:
461:
462: <pre>importScript('io.js');
463: var timer;
464: var symbol;
465: function update() {
466: port.postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
467: timer = setTimeout(update, 10000);
468: }
469: port.onmessage = function (event) {
470: if (timer)
471: clearTimeout(timer);
472: symbol = event.message;
473: update();
474: };</pre>
475:
476: <p>The search query worker is as follows:
477:
478: <pre>importScript('io.js');
479: port.onmessage = function (event) {
480: port.postMessage(get('search.cgi?' + event.message));
481: };</pre>
482:
1.36 ihickson 483: <p><a href="http://www.whatwg.org/demos/workers/stocks/page.html">View this
1.33 ihickson 484: example online</a>.
485:
1.34 ihickson 486: <h4 id=shared><span class=secno>1.1.4 </span>Shared workers</h4>
487:
1.36 ihickson 488: <p><em>This section is non-normative.</em>
489:
490: <p>In this example, multiple windows (viewers) can be opened that are all
491: viewing the same map. All the windows share the same map information, with
492: a single worker coordinating all the viewers. Each viewer can move around
493: idependently, but if they set any data on the map, all the viewers are
494: updated.
495:
496: <p>The main page isn't interesting, it merely provides a way to open the
497: viewers:
498:
499: <pre><!DOCTYPE HTML>
500: <html>
501: <head>
502: <title>Workers example: Multiviewer</title>
503: <script>
504: function openViewer() {
505: window.open('viewer.html');
506: }
507: </script>
508: </head>
509: <body>
510: <p><button type=button onclick="openViewer()">Open a new
511: viewer</button></p>
512: <p>Each viewer opens in a new window. You can have as many viewers
513: as you like, they all view the same data.</p>
514: </body>
515: </html></pre>
516:
517: <p>The viewer is more involved:
518:
519: <pre><!DOCTYPE HTML>
520: <html>
521: <head>
522: <title>Workers example: Multiviewer viewer</title>
523: <script>
524: var worker = createNamedWorker('worker.js', 'core');
525:
526: // CONFIGURATION
527: function configure(event) {
528: if (event.message.substr(0, 4) != 'cfg ') return;
529: var name = event.message.substr(4).split(' ', 1);
530: // update display to mention our name is name
531: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
532: // no longer need this listener
533: worker.removeEventListener('message', configure, false);
534: }
535: worker.addEventListener('message', configure, false);
536:
537: // MAP
538: function paintMap(event) {
539: if (event.message.substr(0, 4) != 'map ') return;
540: var data = event.message.substr(4).split(',');
541: // display tiles data[0] .. data[8]
542: var canvas = document.getElementById('map');
543: var context = canvas.getContext('2d');
544: for (var y = 0; y < 3; y += 1) {
545: for (var x = 0; x < 3; x += 1) {
546: var tile = data[y * 3 + x];
547: if (tile == '0')
548: context.fillStyle = 'green';
549: else
550: context.fillStyle = 'maroon';
551: fillRect(x * 50, y * 50, 50, 50);
552: }
553: }
554: }
555: worker.addEventListener('message', paintMap, false);
556:
557: // PUBLIC CHAT
558: function updatePublicChat(event) {
559: if (event.message.substr(0, 4) != 'txt ') return;
560: var name = event.message.substr(4).split(' ', 1);
561: var message = event.message.substr(4 + length(name) + 1);
562: // display "<name> message" in public chat
563: var dialog = document.getElementById('public');
564: var dt = document.createElement('dt');
565: dt.textContent = name;
566: dialog.appendChild(dt);
567: var dd = document.createElement('dd');
568: dd.textContent = message;
569: dialog.appendChild(dd);
570: }
571: worker.addEventListener('message', updatePublicChat, false);
572:
573: // PRIVATE CHAT
574: function startPrivateChat(event) {
575: if (event.message.substr(0, 4) != 'msg ') return;
576: var name = event.message.substr(4).split(' ', 1);
577: var port = event.port;
578: // display a private chat UI
579: var ul = document.getElementById('private');
580: var li = document.createElement('li');
581: var h3 = document.createElement('h3');
582: h3.textContent = 'Private chat with ' + name;
583: li.appendChild(h3);
584: var dialog = document.createElement('dialog');
585: var addMessage = function(name, message) {
586: var dt = document.createElement('dt');
587: dt.textContent = name;
588: dialog.appendChild(dt);
589: var dd = document.createElement('dd');
590: dd.textContent = message;
591: dialog.appendChild(dd);
592: };
593: port.onmessage = function (event) {
594: addMessage(name, event.message);
595: };
596: li.appendChild(dialog);
597: var form = document.createElement('form');
598: var p = document.createElement('p');
599: var input = document.createElement('input');
600: input.size = 50;
601: p.appendChild(input);
602: p.appendChild(document.createTextNode(' '));
603: var button = document.createElement('button');
604: button.textContent = 'Post';
605: p.appendChild(button);
606: form.onsubmit = function () {
607: port.postMessage(input.value);
608: addMessage('me', input.value);
609: input.value = '';
610: return false;
611: };
612: form.appendChild(p);
613: li.appendChild(form);
614: }
615: worker.addEventListener('message', startPrivateChat, false);
616:
617: function init() {
618: // begin receiving messages (messages are queued until you
619: // either set worker.onmessage or call worker.start())
620: worker.start();
621: }
622: </script>
623: </head>
624: <body onload="init()">
625: <h1>Viewer</h1>
626: <h2>Map</h2>
627: <p><canvas id="map" height=150 width=150></canvas></p>
628: <p>
629: <button type=button onclick="worker.postMessage('mov left')">Left</button>
630: <button type=button onclick="worker.postMessage('mov up')">Up</button>
631: <button type=button onclick="worker.postMessage('mov down')">Down</button>
632: <button type=button onclick="worker.postMessage('mov right')">Right</button>
633: <button type=button onclick="worker.postMessage('set 0')">Set 0</button>
634: <button type=button onclick="worker.postMessage('set 1')">Set 1</button>
635: </p>
636: <h2>Public Chat</h2>
637: <dialog id="public"></dialog>
638: <form onsubmit="worker.postMessage('txt ' + message.value); message.value = ''; return false;">
639: <p>
640: <input type="text" name="message" size="50">
641: <button>Post</button>
642: </p>
643: </form>
644: <h2>Private Chat</h2>
645: <ul id="private"></ul>
646: </body>
647: </html></pre>
648:
649: <p>There are several key things worth noting about the way the viewer is
650: written.
651:
652: <p><strong>Multiple listeners</strong>. Instead of a single message
653: processing function, the code here attaches multiple event listeners, each
654: one performing a quick check to see if it is relevant for the message. In
655: this example it doesn't make much difference, but if multiple authors
656: wanted to collaborate using a single port to communicate with a worker, it
657: would allow for independent code instead of changes having to all be made
658: to a single event handling function.
659:
660: <p>Because event listeners are registered using <code
661: title="">addEventListener()</code> instead of <code
662: title=handler-MessagePort-onmessage>onmessge</code>, the events remain
663: queued until the <code title=dom-MessagePort-start>start()</code> method
664: is called on the message port, in the <code title="">init()</code>
665: function called from the <code title=handler-onload>onload</code> handler.
666:
667: <p>Registering event listeners in this way also allows you to unregister
668: specific listeners when you are done with them, as is done with the <code
669: title="">configure()</code> method in this example.
670:
671: <p>Finally, the worker:
672:
673: <pre>
674: var nextName = 0;
675: function getNextName() {
676: // this could use more friendly names
677: // but for now just return a number
678: return nextName++;
679: }
680:
681: var map = [
682: [0, 0, 0, 0, 0, 0, 0],
683: [1, 1, 0, 1, 0, 1, 1],
684: [0, 1, 0, 1, 0, 0, 0],
685: [0, 1, 0, 1, 0, 1, 1],
686: [0, 0, 0, 1, 0, 0, 0],
687: [1, 0, 0, 1, 1, 1, 1],
688: [1, 1, 0, 1, 1, 0, 1],
689: ];
690:
691: function wrapX(x) {
692: if (x < 0) return wrapX(x + map[0].length);
693: if (x >= map[0].length) return wrapX(x - map[0].length);
694: return x;
695: }
696:
697: function wrapY(y) {
698: if (y < 0) return wrapY(y + map.length);
699: if (y >= map[0].length) return wrapY(y - map.length);
700: return y;
701: }
702:
703: function sendMapData(viewer) {
704: var data = '';
705: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
706: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
707: if (data != '')
708: data += ',';
709: data += map[y][x];
710: }
711: }
712: viewer.port.postMessage('map ' + data);
713: }
714:
715: var viewers = {};
716: onconnect = function (event) {
717: event.port._name = getNextName();
718: event.port._data = { port: event.port, x: 0, y: 0, };
719: viewers[event.port._name] = event.port._data;
720: event.port.postMessage('cfg ' + name);
721: event.port.onmessage = getMessage;
722: sendMapData(event.port._data);
723: };
724:
725: function getMessage(event) {
726: switch (event.message.substr(0, 4)) {
727: case 'mov ':
728: var direction = event.message.substr(4);
729: var dx = 0;
730: var dy = 0;
731: switch (direction) {
732: case 'up': dy = -1; break;
733: case 'down': dy = 1; break;
734: case 'left': dx = -1; break;
735: case 'right': dx = 1; break;
736: }
737: event.target._data.x = wrapX(event.target._data.x + dx);
738: event.target._data.y = wrapY(event.target._data.y + dy);
739: sendMapData(event.target._data);
740: break;
741: case 'set ':
742: var value = event.message.substr(4);
743: map[event.target._data.y][event.target._data.x] = value;
744: for (var viewer in viewers)
745: sendMapData(viewers[viewer]);
746: break;
747: case 'txt ':
748: var name = event.target._name;
749: var message = event.message.substr(4);
750: for (var viewer in viewers)
751: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
752: break;
753: case 'msg ':
754: var party1 = event._data;
755: var party2 = viewers[event.message.substr(4).split(' ', 1)];
756: if (party2) {
757: var channel = new MessageChannel();
758: party1.port.postMessage('msg ' + party2.name, channel.port1);
759: party2.port.postMessage('msg ' + party1.name, channel.port2);
760: }
761: break;
762: }
763: }</pre>
764:
765: <p><strong>Connecting to multiple pages</strong>. Instead of using the
1.37 ihickson 766: <code title=dom-WorkerGlobalScope-port><a href="#port">port</a></code>
767: global variable in the worker, the script uses the <code
768: title=handler-WorkerGlobalScope-onconnect><a
769: href="#onconnect">onconnect</a></code> event listener to listen for
770: multiple connections.
1.36 ihickson 771:
772: <p><strong>Direct channels</strong>. When the worker receives a "msg"
773: message from one viewer naming another viewer, it sets up a direct
774: connection between the two, so that the two viewers can communicate
775: directly without the worker having to proxy all the messages.
776:
777: <p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View
778: this example online</a>.
1.34 ihickson 779:
1.40 ihickson 780: <h4 id=delegation><span class=secno>1.1.5 </span>Delegation</h4>
1.34 ihickson 781:
1.36 ihickson 782: <p><em>This section is non-normative.</em>
783:
1.40 ihickson 784: <p>With multicore CPUs becoming prevalent, one way to obtain better
785: performance is to split computationally expensive tasks amongst multiple
786: workers. In this example, a computationally expensive task that is to be
787: performed for every number from 1 to 10,000,000 is farmed out to ten
788: subworkers.
789:
790: <p>The main page is as follows, it just reports the result:
791:
792: <pre><!DOCTYPE HTML>
793: <html>
794: <head>
795: <title>Worker example: One-core computation</title>
796: </head>
797: <body>
798: <p>The highest prime number discovered so far is: <output id="result"></output></p>
799: <script>
800: var worker = createWorker('worker.js');
801: worker.onmessage = function (event) {
802: document.getElementById('result').textContent = event.message;
803: };
804: </script>
805: </body>
806: </html></pre>
807:
808: <p>The worker itself is as follows:
809:
810: <pre>// settings
811: var num_workers = 10;
812: var items_per_worker = 1000000;
813:
814: // start the workers
815: var result = 0;
816: var pending_workers = num_workers;
817: for (var i = 0; i < num_workers; i += 1) {
818: var worker = createWorker('core.js');
819: worker.postMessage(i * items_per_worker);
820: worker.postMessage((i+1) * items_per_worker);
821: worker.onmessage = storeResult;
822: }
823:
824: // handle the results
825: function storeResult(event) {
826: result += 1*event.message;
827: pending_workers -= 1;
828: if (pending_workers <= 0)
829: port.postMessage(result); // finished!
830: }</pre>
831:
832: <p>It consists of a loop to start the subworkers, and then a handler that
833: waits for all the subworkers to respond.
834:
835: <p>The subworkers are implemented as follows:
836:
837: <pre>var start;
1.41 ihickson 838: onmessage = getStart;
1.40 ihickson 839: function getStart(event) {
840: start = 1*event.message;
841: onmessage = getEnd;
842: }
843:
844: var end;
845: function getEnd(event) {
846: end = 1*event.message;
847: onmessage = null;
848: do();
849: }
850:
851: function do() {
852: var result = 0;
853: for (var i = start; i < end; i += 1) {
854: // perform some complex calculation here
855: result += 1;
856: }
857: port.postMessage(result);
858: }</pre>
859:
860: <p>They receive two numbers in two events, perform the computation for the
861: range of numbers thus specified, and then report the result back to the
862: parent.
863:
864: <p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View
865: this example online</a>.
1.34 ihickson 866:
1.40 ihickson 867: <h4 id=granting><span class=secno>1.1.6 </span>Granting capabilities</h4>
1.34 ihickson 868:
1.36 ihickson 869: <p><em>This section is non-normative.</em>
870:
1.35 ihickson 871: <p class=big-issue>...
1.34 ihickson 872:
1.22 ihickson 873: <h3 id=conformance><span class=secno>1.2 </span>Conformance requirements</h3>
1.1 ihickson 874:
875: <p>All diagrams, examples, and notes in this specification are
876: non-normative, as are all sections explicitly marked non-normative.
877: Everything else in this specification is normative.
878:
879: <p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
880: NOT",-->
881: "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the
882: normative parts of this document are to be interpreted as described in
883: RFC2119. For readability, these words do not appear in all uppercase
884: letters in this specification. <a href="#refsRFC2119">[RFC2119]</a></p>
885: <!-- XXX but they should be
886: marked up -->
887:
888: <p>Requirements phrased in the imperative as part of algorithms (such as
889: "strip any leading space characters" or "return false and abort these
890: steps") are to be interpreted with the meaning of the key word ("must",
891: "should", "may", etc) used in introducing the algorithm.
892:
893: <p>Some conformance requirements are phrased as requirements on attributes,
894: methods or objects. Such requirements are to be interpreted as
895: requirements on user agents.
896:
897: <p>Conformance requirements phrased as algorithms or specific steps may be
898: implemented in any manner, so long as the end result is equivalent. (In
899: particular, the algorithms defined in this specification are intended to
900: be easy to follow, and not intended to be performant.)
901:
902: <p>The only conformance class defined by this specification is user agents.
903:
904: <p>User agents may impose implementation-specific limits on otherwise
905: unconstrained inputs, e.g. to prevent denial of service attacks, to guard
906: against running out of memory, or to work around platform-specific
907: limitations.
908:
1.22 ihickson 909: <h4 id=dependencies><span class=secno>1.2.1 </span>Dependencies</h4>
1.1 ihickson 910:
911: <p>This specification relies on several other underlying specifications.
912:
913: <dl>
914: <dt>HTML5
915:
916: <dd>
917: <p>Many fundamental concepts from HTML5 are used by this specification.
918: <a href="#refsHTML5">[HTML5]</a></p>
919:
920: <dt>ECMAScript
921:
922: <dd>
923: <p>This specification is intended to be used with JavaScript as the
924: scripting language. <a href="#refsJS">[JS]</a></p>
925:
926: <dt>WebIDL
927:
928: <dd>
929: <p>The IDL blocks in this specification use the semantics of the WebIDL
930: specification. <a href="#refsWebIDL">[WebIDL]</a></p>
931: </dl>
932:
1.22 ihickson 933: <h3 id=terminology><span class=secno>1.3 </span>Terminology</h3>
1.1 ihickson 934:
935: <p>For simplicity, terms such as <em>shown</em>, <em>displayed</em>, and
936: <em>visible</em> might sometimes be used when referring to the way a
937: document is rendered to the user. These terms are not meant to imply a
938: visual medium; they must be considered to apply to other media in
939: equivalent ways.
940:
1.4 ihickson 941: <p>The construction "a <code title="">Foo</code> object", where <code
942: title="">Foo</code> is actually an interface, is sometimes used instead of
943: the more accurate "an object implementing the interface <code
944: title="">Foo</code>".
1.1 ihickson 945:
946: <p>The term DOM is used to refer to the API set made available to scripts
947: in Web applications, and does not necessarily imply the existence of an
948: actual <code>Document</code> object or of any other <code>Node</code>
949: objects as defined in the DOM Core specifications. <a
950: href="#refsDOM3CORE">[DOM3CORE]</a>
951:
952: <p>A DOM attribute is said to be <em>getting</em> when its value is being
953: retrieved (e.g. by author script), and is said to be <em>setting</em> when
954: a new value is assigned to it.
955:
956: <p>If a DOM object is said to be <dfn id=live>live</dfn>, then that means
957: that any attributes returning that object must always return the same
958: object (not a new object each time), and the attributes and methods on
959: that object must operate on the actual underlying data, not a snapshot of
960: the data.
961:
1.12 ihickson 962: <h2 id=infrastructure><span class=secno>2. </span>Infrastructure</h2>
1.4 ihickson 963:
1.26 ihickson 964: <h3 id=the-workerglobalscope><span class=secno>2.1 </span>The <code><a
965: href="#workerglobalscope">WorkerGlobalScope</a></code> interface</h3>
1.4 ihickson 966:
967: <pre
1.26 ihickson 968: class=idl>[NoInterfaceObject] interface <dfn id=workerglobalscope>WorkerGlobalScope</dfn> {
969: // core worker features
970: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#self" title=dom-WorkerGlobalScope-self>self</a>;
1.34 ihickson 971: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#location" title=dom-WorkerGlobalScope-location>location</a>;
1.26 ihickson 972: readonly attribute DOMString <a href="#name" title=dom-WorkerGlobalScope-name>name</a>;
973: readonly attribute boolean <a href="#closing" title=dom-WorkerGlobalScope-closing>closing</a>;
974: void <a href="#close" title=dom-WorkerGlobalScope-close>close</a>();
975:
1.9 ihickson 976: // event handler attributes
1.26 ihickson 977: attribute <span>EventListener</span> <a href="#onconnect" title=handler-WorkerGlobalScope-onconnect>onconnect</a>;
978: attribute <span>EventListener</span> <a href="#onunload" title=handler-WorkerGlobalScope-onunload>onunload</a>;
1.4 ihickson 979: };</pre>
980:
1.39 ihickson 981: <p>Objects implementing the <code><a
982: href="#workerglobalscope">WorkerGlobalScope</a></code> interface must also
983: implement the <code>EventTarget</code> interface.
984:
1.26 ihickson 985: <p>The <dfn id=self
986: title=dom-WorkerGlobalScope-self><code>self</code></dfn> attribute must
987: return the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
988: object itself.
1.9 ihickson 989:
1.34 ihickson 990: <p>The <dfn id=location
991: title=dom-WorkerGlobalScope-location><code>location</code></dfn> attribute
992: must return the <code><a href="#workerlocation">WorkerLocation</a></code>
993: object created for the <code><a
994: href="#workerglobalscope">WorkerGlobalScope</a></code> object when the
995: worker was created. It represents the <span>absolute URL</span> of the
996: script that was used to initialize the worker.
1.26 ihickson 997:
998: <p>The <dfn id=name
999: title=dom-WorkerGlobalScope-name><code>name</code></dfn> attribute must
1000: return the value it was assigned when the <code><a
1001: href="#workerglobalscope">WorkerGlobalScope</a></code> object was created
1002: by the "<a href="#run-a">run a worker</a>" algorithm. If it has a value
1003: that isn't the empty string, its value represents the name that can be
1004: used to obtain a reference to the worker using the <code
1005: title=dom-WorkerFactory-createNamedWorker><a
1.11 ihickson 1006: href="#createnamedworker">createNamedWorker()</a></code> method.
1.6 ihickson 1007:
1.4 ihickson 1008: <p>The <dfn id=closing
1.26 ihickson 1009: title=dom-WorkerGlobalScope-closing><code>closing</code></dfn> attribute
1010: must return false until it is set to true by one of the algorithms in the
1.19 ihickson 1011: processing model section below.
1.4 ihickson 1012:
1.9 ihickson 1013: <p>The following are the <span>event handler DOM attributes</span> that
1014: must be supported by objects implementing the <code><a
1.26 ihickson 1015: href="#workerglobalscope">WorkerGlobalScope</a></code> interface:
1.9 ihickson 1016:
1017: <dl>
1.20 ihickson 1018: <dt><dfn id=onconnect
1.26 ihickson 1019: title=handler-WorkerGlobalScope-onconnect><code>onconnect</code></dfn>
1.9 ihickson 1020:
1021: <dd>
1022: <p>Must be invoked whenever a <code
1.26 ihickson 1023: title=event-WorkerGlobalScope-connect>connect</code> event is targeted
1024: at or bubbles through the <code><a
1025: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.9 ihickson 1026:
1027: <dt><dfn id=onunload
1.26 ihickson 1028: title=handler-WorkerGlobalScope-onunload><code>onunload</code></dfn>
1.9 ihickson 1029:
1030: <dd>
1031: <p>Must be invoked whenever a <code title=event-unload>unload</code>
1032: event is targeted at or bubbles through the <code><a
1.26 ihickson 1033: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.9 ihickson 1034: </dl>
1035:
1.30 ihickson 1036: <p>In addition to the above members, the <a href="#success" title="worker
1037: creation succeeded">worker creation success steps</a> add a <dfn id=port
1038: title=dom-WorkerGlobalScope-port><code>port</code></dfn> property to the
1039: object.
1040:
1.15 ihickson 1041: <h3 id=base-urls><span class=secno>2.2 </span>Base URLs and origins of
1042: workers</h3>
1043:
1044: <p>The <span>base URL</span> of a <span>URL</span> passed to an API in a
1.34 ihickson 1045: worker is the <span>absolute URL</span> given that the worker's <code
1046: title=dom-WorkerGlobalScope-location><a
1047: href="#location">location</a></code> attribute represents.
1.15 ihickson 1048:
1.25 ihickson 1049: <p>Both the <span>origin</span> and <span>effective script origin</span> of
1050: scripts running in workers are the <span>origin</span> of the
1.34 ihickson 1051: <span>absolute URL</span> given that the worker's <code
1052: title=dom-WorkerGlobalScope-location><a
1053: href="#location">location</a></code> attribute represents.
1.15 ihickson 1054:
1055: <h3 id=the-queue><span class=secno>2.3 </span>The queue of events</h3>
1.4 ihickson 1056:
1.26 ihickson 1057: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1058: object is asssociated with a <dfn id=queue>queue of events</dfn>, which is
1059: initially empty.
1.4 ihickson 1060:
1061: <p>An event in the queue can be a DOM event or a timeout callback.
1062:
1.8 ihickson 1063: <p>All asynchronous callbacks and events that would be called or dispatched
1064: in the worker must be added to the worker's queue, with the "<a
1065: href="#run-a">run a worker</a>" processing model below taking care of
1066: actually calling the callbacks or dispatching the events.
1067:
1.26 ihickson 1068: <p>Once the <code><a
1069: href="#workerglobalscope">WorkerGlobalScope</a></code>'s <code
1070: title=dom-WorkerGlobalScope-closing><a href="#closing">closing</a></code>
1.8 ihickson 1071: attribute is set to true, the queue must discard anything else that would
1072: be added to it. Effectively, once the <code
1.26 ihickson 1073: title=dom-WorkerGlobalScope-closing><a href="#closing">closing</a></code>
1.8 ihickson 1074: attribute is true, timers stop firing, notifications for all pending
1075: asynchronous operations are dropped, etc.
1076:
1.15 ihickson 1077: <h3 id=the-workers><span class=secno>2.4 </span>The worker's ports</h3>
1.9 ihickson 1078:
1079: <p>Workers communicate with other workers and with <span title="browsing
1080: context">browsing contexts</span> through <span title="channel
1081: messaging">message channels</span> and their <code>MessagePort</code>
1082: objects.
1083:
1.26 ihickson 1084: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1085: <var title="">worker</var> has a list of <dfn id=the-workers0>the worker's
1.9 ihickson 1086: ports</dfn>, which consists of all the <code>MessagePort</code> objects
1087: that are entangled with another port and that have one (but only one) port
1.26 ihickson 1088: owned by <var title="">worker</var>. This list includes all the
1089: <code>MessagePort</code> objects that are in events pending in the <a
1090: href="#queue">queue of events</a>.
1.9 ihickson 1091:
1.17 ihickson 1092: <hr>
1093:
1.38 ihickson 1094: <p>A worker is said to be a <dfn id=permissible>permissible worker</dfn> if
1095: either:
1096:
1097: <ul>
1098: <li>at some point past or present a <code>MessagePort</code> owned by the
1099: worker was entangled with a <code>MessagePort</code> <var
1100: title="">p</var> whose owner is a <code>Window</code> object whose
1101: <span>active document</span> is the <code>Document</code> that was that
1102: <span>browsing context</span>'s <span>active document</span> when <var
1103: title="">p</var> was created, and that <code>Document</code> is
1104: <span>fully active</span>, or
1105:
1106: <li>at some point past or present a <code>MessagePort</code> owned by the
1107: worker was entangled with a <code>MessagePort</code> owned by another
1108: worker that is currently a <a href="#permissible">permissible worker</a>.
1109: </ul>
1110:
1111: <hr>
1112:
1113: <p>A worker is said to be a <dfn id=protected>protected worker</dfn> if
1114: either:
1115:
1116: <ul>
1117: <li>it has outstanding timers, database transactions, or network
1118: connections, and is a <a href="#permissible">permissible worker</a>, or:
1119:
1120: <li>there is a <a href="#protected">protected worker</a> that at some
1121: point past or present owned a <code>MessagePort</code> that was entangled
1122: with a <code>MessagePort</code> owned by this worker.
1123: </ul>
1124:
1125: <hr>
1.17 ihickson 1126:
1.38 ihickson 1127: <p>A worker is said to be an <dfn id=active>active needed worker</dfn> if
1128: either:
1.17 ihickson 1129:
1130: <ul>
1.38 ihickson 1131: <li>the worker is a <a href="#protected">protected worker</a>, or
1132:
1133: <li>at least one of the <a href="#the-workers0">the worker's ports</a> is
1134: entangled with a <code>MessagePort</code> <var title="">p</var> whose
1135: owner is a <code>Window</code> object whose <span>active document</span>
1136: is the <code>Document</code> that was that <span>browsing
1137: context</span>'s <span>active document</span> when that
1138: <code>MessagePort</code> <var title="">p</var> was created, and that
1139: <code>Document</code> is <span>fully active</span>, or
1.17 ihickson 1140:
1141: <li>at least one of the <a href="#the-workers0">the worker's ports</a> has
1.26 ihickson 1142: an entangled <code>MessagePort</code> owned by a <code><a
1143: href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
1.38 ihickson 1144: itself an <a href="#active">active needed worker</a>.
1.17 ihickson 1145: </ul>
1146:
1147: <hr>
1148:
1.38 ihickson 1149: <p>A worker is said to be a <dfn id=suspendable>suspendable worker</dfn> if
1150: it is not an <a href="#active">active needed worker</a> but either:
1.17 ihickson 1151:
1152: <ul>
1.38 ihickson 1153: <li>at least one of the <a href="#the-workers0">the worker's ports</a> has
1154: an entangled <code>MessagePort</code> owned by a <code>Window</code>
1155: object, or
1.17 ihickson 1156:
1157: <li>at least one of the <a href="#the-workers0">the worker's ports</a> has
1.26 ihickson 1158: an entangled <code>MessagePort</code> owned by a <code><a
1159: href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
1.38 ihickson 1160: itself a <span>needed worker</span>.
1.17 ihickson 1161: </ul>
1162:
1.15 ihickson 1163: <h3 id=processing><span class=secno>2.5 </span>Processing model</h3>
1.4 ihickson 1164:
1.6 ihickson 1165: <p>When a user agent is to <dfn id=run-a>run a worker</dfn> named <var
1.7 ihickson 1166: title="">name</var> for a script with <span>URL</span> <var
1167: title="">url</var>, a browsing context <var title="">owner browsing
1168: context</var> and a <code>Document</code> <var title="">owner
1169: document</var>, it must run the following steps in a completely separate
1170: and parallel execution environment:
1.4 ihickson 1171:
1172: <ol>
1173: <li>
1.7 ihickson 1174: <p>Attempt to <span>fetch</span><!-- XXX --> the resource identified by
1175: <var title="">url</var>.</p>
1176:
1177: <p>If the attempt fails, then abort these steps and invoke the <a
1.34 ihickson 1178: href="#worker1" title="worker creation failed">error handling steps</a>
1.7 ihickson 1179: defined by the algorithm that called this one.</p>
1180:
1181: <p>If the attempt succeeds, then let <var title="">script</var> be the
1182: resource that was obtained.</p>
1183:
1184: <p class=note>As with <code>script</code> elements, the MIME type of the
1185: script is ignored. Unlike with <code>script</code> elements, there is no
1186: way to override the type. It's always assumed to be JavaScript.</p>
1187: <!-- XXX people will complain about
1188: this. I guess we might want to examine the MIME type... -->
1189:
1190:
1191: <li>
1.26 ihickson 1192: <p>Create a new <code><a
1193: href="#workerglobalscope">WorkerGlobalScope</a></code> object, <var
1194: title="">worker</var>.</p>
1.4 ihickson 1195:
1196: <li>
1.26 ihickson 1197: <p>Set the <code title=dom-WorkerGlobalScope-name><a
1.19 ihickson 1198: href="#name">name</a></code> attribute of <var title="">worker</var> to
1.6 ihickson 1199: the value of <var title="">name</var>.</p>
1200:
1201: <li>
1.34 ihickson 1202: <p>Create a new <code><a href="#workerlocation">WorkerLocation</a></code>
1203: object for the <code title=dom-WorkerGlobalScope-location><a
1204: href="#location">location</a></code> attribute of <var
1205: title="">worker</var>, representing <var title="">url</var>.</p>
1206:
1207: <li>
1.4 ihickson 1208: <p>Let <var title="">script</var>'s <span>script execution context</span>
1209: (and thus also <span>global object</span>) be <var
1.19 ihickson 1210: title="">worker</var>.</p>
1.4 ihickson 1211:
1212: <li>
1213: <p>Let <var title="">script</var>'s <span>script browsing context</span>
1214: be <var title="">owner browsing context</var>.</p>
1215:
1216: <li>
1217: <p>Let <var title="">script</var>'s <span>script document context</span>
1218: be <var title="">owner document</var>.</p>
1219:
1220: <li>
1.9 ihickson 1221: <p>Invoke the <a href="#success" title="worker creation
1222: succeeded">success steps</a> defined by the algorithm that called this
1.17 ihickson 1223: one.</p>
1224:
1225: <p class=note>This will usually add an event to the <a
1.28 ihickson 1226: href="#queue">queue of events</a> and set the <code
1.30 ihickson 1227: title=dom-WorkerGlobalScope-port><a href="#port">port</a></code>
1228: property on the <var title="">worker</var> object. If it does, that
1229: event will have a <code>MessagePort</code> and thus the list of <a
1.17 ihickson 1230: href="#the-workers0">the worker's ports</a> will not be empty. If it
1.19 ihickson 1231: doesn't, then the next step will set the <var title="">worker</var>
1.26 ihickson 1232: object's <code title=dom-WorkerGlobalScope-closing><a
1.17 ihickson 1233: href="#closing">closing</a></code> attribute to true.</p>
1234:
1235: <li>
1.28 ihickson 1236: <p><strong>Closing orphan workers</strong>: Start monitoring <var
1.38 ihickson 1237: title="">worker</var>, such that as soon as the worker stops being
1238: either an <a href="#active">active needed worker</a> or a <a
1239: href="#suspendable">suspendable worker</a>, the <var
1240: title="">worker</var> object's <code
1241: title=dom-WorkerGlobalScope-closing><a
1.17 ihickson 1242: href="#closing">closing</a></code> attribute is set to true.</p>
1.9 ihickson 1243:
1244: <li>
1.28 ihickson 1245: <p><strong>Suspending workers</strong>: Start monitoring <var
1246: title="">worker</var>, such that whenever the <var title="">worker</var>
1247: object's <code title=dom-WorkerGlobalScope-closing><a
1.26 ihickson 1248: href="#closing">closing</a></code> attribute is false and the worker is
1.38 ihickson 1249: a <a href="#suspendable">suspendable worker</a>, the user agent suspends
1250: execution of script in that worker until such time as either the <code
1251: title=dom-WorkerGlobalScope-closing><a
1.26 ihickson 1252: href="#closing">closing</a></code> attribute switches to true or the
1.38 ihickson 1253: worker stops being a <a href="#suspendable">suspendable worker</a>.</p>
1.7 ihickson 1254:
1255: <li>
1256: <p>Run <var title="">script</var> until it either returns, fails to catch
1257: an exception, or gets prematurely aborted by the "<a href="#kill-a">kill
1258: a worker</a>" algorithm below.</p>
1259:
1260: <p class=note>If the script gets aborted by the "<a href="#kill-a">kill a
1261: worker</a>" algorithm, then that same algorithm will cause there to only
1262: be a single event in the <a href="#queue">queue of events</a> at the
1.28 ihickson 1263: next step, namely the <code title=message-unload>unload</code> event.</p>
1.4 ihickson 1264:
1265: <li>
1.9 ihickson 1266: <p><i>Event loop</i>: Wait until either there is an event in the <a
1.4 ihickson 1267: href="#queue">queue of events</a> associated with <var
1.19 ihickson 1268: title="">worker</var> or the <var title="">worker</var> object's <code
1.26 ihickson 1269: title=dom-WorkerGlobalScope-closing><a
1270: href="#closing">closing</a></code> attribute is set to true.</p>
1.4 ihickson 1271:
1272: <li>
1273: <p>Dispatch the oldest event or callback in the <a href="#queue">queue of
1.9 ihickson 1274: events</a>, if any. The handling of this event or the execution of this
1275: callback might get prematurely aborted by the "<a href="#kill-a">kill a
1.8 ihickson 1276: worker</a>" algorithm below.</p>
1.4 ihickson 1277:
1278: <li>
1279: <p>If there are any more events in the <a href="#queue">queue of
1.19 ihickson 1280: events</a> or if the <var title="">worker</var> object's <code
1.26 ihickson 1281: title=dom-WorkerGlobalScope-closing><a
1282: href="#closing">closing</a></code> attribute is set to false, then jump
1283: back to the step above labeled <i>event loop</i>.</p>
1.4 ihickson 1284:
1285: <li>
1286: <p class=big-issue>timers, intervals, XMLHttpRequests, database
1.28 ihickson 1287: transactions, etc, must be killed; ports must be unentangled</p>
1.4 ihickson 1288: </ol>
1289:
1290: <hr>
1291:
1292: <p>When a user agent is to <dfn id=kill-a>kill a worker</dfn>, it must run
1293: the following steps in parallel with the worker's main loop (the "<a
1294: href="#run-a">run a worker</a>" processing model defined above):
1295:
1296: <ol>
1297: <li>
1298: <p>Create an <code>Event</code> object with the event name <code
1299: title=event-unload>unload</code>, which does not bubble and is not
1300: cancelable, and add it to the worker's <code><a
1.26 ihickson 1301: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.8 ihickson 1302: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 1303: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.28 ihickson 1304: </li>
1305: <!-- XXX shouldn't add one if closing is
1306: already true, assuming unload has already been added to the queue
1307: (?) -->
1.4 ihickson 1308:
1309: <li>
1.26 ihickson 1310: <p>Set the worker's <code><a
1311: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code
1312: title=dom-WorkerGlobalScope-closing><a
1.8 ihickson 1313: href="#closing">closing</a></code> attribute to true.
1314:
1315: <li>
1316: <p>Wait a user-agent-defined amount of time. If the "<a href="#run-a">run
1317: a worker</a>" processing model defined above immediately starts running
1.28 ihickson 1318: event listeners registered for the <code
1319: title=event-unload>unload</code> event, this time should not be zero
1320: — the idea is that the <code title=event-unload>unload</code>
1321: event can be used to clean up when shutting down unexpectedly.
1.4 ihickson 1322:
1323: <li>
1324: <p>If there are any events in the <a href="#queue">queue of events</a>
1325: other than the <code title=event-unload>unload</code> event that this
1326: algorithm just added, discard them without dispatching them.
1327:
1328: <li>
1329: <p>If the <code title=event-unload>unload</code> event that this
1330: algorithm just added hasn't yet been dispatched, then abort the script
1331: currently running in the worker.
1332:
1333: <li>
1334: <p>Wait a user-agent-defined amount of time.
1335:
1336: <li>
1337: <p>Abort the script currently running in the worker (if any script is
1338: running, then it will be a handler for the <code
1339: title=event-unload>unload</code> event).
1340: </ol>
1341:
1.19 ihickson 1342: <p>User agents may invoke the "<a href="#kill-a">kill a worker</a>"
1343: processing model on a worker at any time, e.g. in response to user
1344: requests, in response to CPU quota management, or when a worker stops
1.38 ihickson 1345: being an <a href="#active">active needed worker</a> if the worker
1346: continues executing even after its <code
1347: title=dom-WorkerGlobalScope-closing><a href="#closing">closing</a></code>
1348: attribute was set to true.
1.19 ihickson 1349:
1.8 ihickson 1350: <hr>
1351:
1352: <p>When a script invokes the <dfn id=close
1.26 ihickson 1353: title=dom-WorkerGlobalScope-close><code>close()</code></dfn> method on a
1354: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object,
1355: the user agent must run the following steps:
1.8 ihickson 1356:
1357: <ol>
1358: <li>
1359: <p>Create an <code>Event</code> object with the event name <code
1360: title=event-unload>unload</code>, which does not bubble and is not
1361: cancelable, and add it to the <code><a
1.26 ihickson 1362: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.8 ihickson 1363: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 1364: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.8 ihickson 1365:
1366: <li>
1.26 ihickson 1367: <p>Set the worker's <code><a
1368: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code
1369: title=dom-WorkerGlobalScope-closing><a
1.8 ihickson 1370: href="#closing">closing</a></code> attribute to true.
1371:
1372: <li>
1373: <p>For each <code>MessagePort</code> object that is entangled with
1.26 ihickson 1374: another port and that has one (but only one) port whose owner is the
1375: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
1376: on which the method was invoked, run the following substeps:</p>
1.8 ihickson 1377:
1378: <ol>
1379: <li>
1380: <p>Unentangle the two ports.
1381:
1382: <li>
1383: <p>At the next available opportunity, after any scripts have finished
1384: executing<!-- XXX queue -->, <span>fire a simple event</span> called
1385: <code title=event-unload>unload</code> at the other port (the one
1.26 ihickson 1386: whose owner is not the <code><a
1387: href="#workerglobalscope">WorkerGlobalScope</a></code> object on which
1388: the <code title=dom-WorkerGlobalScope-close><a
1.8 ihickson 1389: href="#close">close()</a></code> method was called).
1390: </ol>
1391: </ol>
1392:
1.15 ihickson 1393: <h3 id=creating><span class=secno>2.6 </span>Creating workers</h3>
1.5 ihickson 1394:
1395: <pre
1.26 ihickson 1396: class=idl>[NoInterfaceObject] interface <dfn id=workerfactory>WorkerFactory</dfn> {
1397: <span>MessagePort</span> <a href="#createworker" title=dom-WorkerFactory-createWorker>createWorker</a>(in DOMString scriptURL);
1398: <span>MessagePort</span> <a href="#createnamedworker" title=dom-WorkerFactory-createNamedWorker>createNamedWorker</a>(in DOMString name, in DOMString scriptURL);
1.5 ihickson 1399: };</pre>
1400:
1.26 ihickson 1401: <p>Objects that implement the <code>Window</code> and <code><a
1.42 ! ihickson 1402: href="#workerglobalscope">WorkerGlobalScope</a></code> interfaces must
! 1403: also implement the <code><a href="#workerfactory">WorkerFactory</a></code>
! 1404: interface.
1.5 ihickson 1405:
1.9 ihickson 1406: <hr>
1407:
1.11 ihickson 1408: <p>When the <dfn id=createworker
1.26 ihickson 1409: title=dom-WorkerFactory-createWorker><code>createWorker(<var
1.11 ihickson 1410: title="">scriptURL</var>)</code></dfn> method is invoked, the user agent
1411: must run the following steps:
1.9 ihickson 1412:
1413: <ol>
1414: <li>
1415: <p><span title="resolve a url">Resolve</span> the <var
1416: title="">scriptURL</var> argument.
1417:
1418: <li>
1419: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
1420:
1421: <li>
1422: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
1423: is not the <span title="same origin">same</span> as the origin of the
1424: script that invoked the method, then throw a <span>security
1425: exception</span>.
1426:
1427: <li>
1428: <p><a href="#create">Create a worker</a> from the resulting
1429: <span>absolute URL</span> whose name is the empty string.
1430:
1431: <li>
1432: <p>Return the <code>MessagePort</code> object returned from the <a
1433: href="#create">create a worker</a> algorithm.
1434: </ol>
1435:
1436: <hr>
1437:
1.11 ihickson 1438: <p>When the <dfn id=createnamedworker
1.26 ihickson 1439: title=dom-WorkerFactory-createNamedWorker><code>createNamedWorker(<var
1.11 ihickson 1440: title="">name</var>, <var title="">scriptURL</var>)</code></dfn> method is
1.9 ihickson 1441: invoked, the user agent must run the following steps:
1442:
1443: <ol>
1444: <li>
1445: <p><span title="resolve a url">Resolve</span> the <var
1446: title="">scriptURL</var> argument.
1.4 ihickson 1447:
1.9 ihickson 1448: <li>
1449: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
1450:
1451: <li>
1452: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
1453: is not the <span title="same origin">same</span> as the origin of the
1454: script that invoked the method, then throw a <span>security
1455: exception</span>.
1456:
1457: <li>
1458: <p>If the <var title="">name</var> argument is the empty string, <a
1459: href="#create">create a worker</a> from the resulting <span>absolute
1460: URL</span>, whose name is the empty string, and return the
1461: <code>MessagePort</code> object returned from the <a
1462: href="#create">create a worker</a> algorithm. Then, abort these steps.
1463:
1464: <li>
1.26 ihickson 1465: <p>If there exists a worker whose <code
1466: title=dom-WorkerGlobalScope-closing><a
1.9 ihickson 1467: href="#closing">closing</a></code> attribute is false, whose <code
1.26 ihickson 1468: title=dom-WorkerGlobalScope-name><a href="#name">name</a></code>
1469: attribute is exactly equal to the <var title="">name</var> argument, and
1.34 ihickson 1470: whose <code title=dom-WorkerGlobalScope-location><a
1471: href="#location">location</a></code> attribute represents an
1472: <span>absolute URL</span> that has the <span>same origin</span> as the
1473: resulting <span>absolute URL</span>, then run these substeps:</p>
1.9 ihickson 1474:
1475: <ol>
1476: <li>
1.34 ihickson 1477: <p>If that worker's <code title=dom-WorkerGlobalScope-location><a
1478: href="#location">location</a></code> attribute represents an
1479: <span>absolute URL</span> that is not exactly equal to the resulting
1480: <span>absolute URL</span>, then throw a <code>URL_MISMATCH_ERR</code>
1481: exception and abort these steps. <span class=big-issue>code 19</span>
1.9 ihickson 1482:
1483: <li>
1484: <p><span>Create a new <code>MessagePort</code> object</span> owned by
1485: the <span>script execution context</span> of the script that invoked
1486: the method.
1487:
1488: <li>
1489: <p>Return that port.
1490:
1491: <li>
1.20 ihickson 1492: <p>Asynchronously, <a href="#connect" title="connect to a
1493: worker">connect</a> to this preexisting worker, with the newly created
1.9 ihickson 1494: port.
1495: </ol>
1496:
1497: <p>Otherwise, <a href="#create">create a worker</a> from the resulting
1498: <span>absolute URL</span>, whose name is the value of the <var
1499: title="">name</var> argument, and return the <code>MessagePort</code>
1500: object returned from the <a href="#create">create a worker</a>
1501: algorithm.</p>
1502: </ol>
1503:
1504: <hr>
1505:
1506: <p>The steps to <dfn id=create>create a worker</dfn> from a
1507: <span>URL</span> <var title="">url</var> and whose name is <var
1508: title="">name</var>, in the context of a method call, are as follows:
1509:
1510: <ol>
1511: <li>
1512: <p><span>Create a new <code>MessagePort</code> object</span> owned by the
1513: <span>script execution context</span> of the script that invoked the
1514: method.
1515:
1516: <li>
1517: <p>Return that port.
1518:
1519: <li>
1520: <p>In a parallel execution context (i.e. a separate thread or process or
1521: equivalent construct), <a href="#run-a">run a worker</a> named <var
1522: title="">name</var> for the script with <span>URL</span> <var
1523: title="">url</var>, with the <span>script browsing context</span> of the
1524: script that invoked the method as the <var title="">owner browsing
1525: context</var> and with the <span>script document context</span> of the
1526: script that invoked the method as the <var title="">owner
1527: document</var>.</p>
1528:
1529: <p>If that algorithm invokes the steps for <dfn id=success title="worker
1.20 ihickson 1530: creation succeeded">success steps</dfn>, then <a href="#connect"
1531: title="connect to a worker">connect</a> to this new worker, with the
1.28 ihickson 1532: newly created port, and if that algorithm returns a second new port,
1.30 ihickson 1533: then add a new property <code title=dom-WorkerGlobalScope-port><a
1534: href="#port">port</a></code> on the new worker's <code><a
1535: href="#workerglobalscope">WorkerGlobalScope</a></code> object, whose
1536: value is the <code>MessagePort</code> object return by the <a
1.28 ihickson 1537: href="#connect">connect to a worker</a> algorithm.</p>
1.9 ihickson 1538:
1.34 ihickson 1539: <p>Otherwise, if the <dfn id=worker1>worker creation failed</dfn>, then
1.33 ihickson 1540: at the next available opportunity, after any scripts have finished
1.9 ihickson 1541: executing<!-- XXX queue -->, <span>fire a simple event</span> called
1542: <code title=event-error>error</code> at the newly created port.</p>
1543: </ol>
1544:
1545: <hr>
1546:
1.20 ihickson 1547: <p>The steps to <dfn id=connect>connect to a worker</dfn> given a
1.9 ihickson 1548: <code>MessagePort</code> object <var title="">port</var> are as follows:
1549:
1550: <ol>
1551: <li>
1552: <p>If <var title="">port</var> would have been garbage collected, or if
1.26 ihickson 1553: the <span>active document</span> of the owner of <var
1.9 ihickson 1554: title="">port</var> is no longer the same <code>Document</code> object
1555: as when <var title="">port</var> was created, then do nothing. Abort
1556: these steps. If the worker was just created, it'll get killed
1557: immediately.</p>
1558:
1559: <li>
1560: <p><span>Create a new <code>MessagePort</code> object</span> owned by the
1.26 ihickson 1561: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> of the
1562: worker.
1.9 ihickson 1563:
1564: <li>
1565: <p><span>Entangle</span> this newly created port and the port <var
1566: title="">port</var> that was passed to these steps.
1567:
1568: <li>
1569: <p>At the next available opportunity, after any scripts have finished
1570: executing<!-- XXX queue -->, <span>fire a simple event</span> called
1571: <code title=event-load>load</code> at <var title="">port</var>.
1572:
1573: <li>
1574: <p>Create an event that uses the <code>MessageEvent</code> interface,
1.20 ihickson 1575: with the name <code title=event-connect>connect</code>, which does not
1.9 ihickson 1576: bubble, is cancelable, has no default action, has a <code
1577: title=dom-MessageEvent-data>data</code> attribute whose value is the
1578: empty string and has a <code
1579: title=dom-MessageEvent-messagePort>messagePort</code> attribute whose
1580: value is the newly created port, and add it to the worker's <code><a
1.26 ihickson 1581: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.9 ihickson 1582: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 1583: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.28 ihickson 1584:
1585: <li>
1586: <p>Return the newly created port.
1.9 ihickson 1587: </ol>
1.7 ihickson 1588:
1.12 ihickson 1589: <h2 id=apis-available><span class=secno>3. </span>APIs available to workers</h2>
1590:
1.26 ihickson 1591: <pre
1592: class=idl>[NoInterfaceObject] interface <dfn id=workerutils>WorkerUtils</dfn> {
1.27 ihickson 1593: boolean <a href="#importscript" title=dom-WorkerGlobalScope-importScript>importScript</a>(in DOMString url);
1.26 ihickson 1594: readonly attribute <span>Storage</span> <a href="#localstorage" title=dom-localStorage>localStorage</a>;
1595: <span>Database</span> <a href="#opendatabase" title=dom-opendatabase>openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize);
1596: void <a href="#shownotification" title=dom-showNotification>showNotification</a>(in DOMString title, in DOMString subtitle, in DOMString description);
1597: void <a href="#shownotification" title=dom-showNotification>showNotification</a>(in DOMString title, in DOMString subtitle, in DOMString description, in VoidCallback onclick);
1598: };</pre>
1.18 ihickson 1599:
1.12 ihickson 1600: <p>Objects that implement the <code><a
1.42 ! ihickson 1601: href="#workerglobalscope">WorkerGlobalScope</a></code> interface must also
! 1602: implement the <code><a href="#workerutils">WorkerUtils</a></code>
! 1603: interface.
1.12 ihickson 1604:
1.23 ihickson 1605: <p class=big-issue>Need to define a sync database API.
1606:
1607: <p class=big-issue>May need to define a browser sniffing API (like
1608: window.navigator).</p>
1.18 ihickson 1609: <!-- XXX ApplicationCache -->
1610: <!-- XXX a way to set cookies on the URL for the script -->
1.24 ihickson 1611: <!-- XXX debugging: void log(in DOMString s); // log to console -->
1612: <!-- XXX debugging: onerror -->
1.13 ihickson 1613:
1.18 ihickson 1614: <hr>
1.13 ihickson 1615:
1.18 ihickson 1616: <p>The DOM APIs (<code>Node</code> objects, <code>Document</code> objects,
1617: etc) are not available to workers in this version of this specification.
1.13 ihickson 1618:
1.26 ihickson 1619: <h3 id=importing><span class=secno>3.1 </span>Importing scripts and
1620: libraries</h3>
1621:
1.27 ihickson 1622: <p>When a script invokes the <dfn id=importscript
1623: title=dom-WorkerGlobalScope-importScript><code>importScript(<var
1.26 ihickson 1624: title="">url</var>)</code></dfn> method on a <code><a
1625: href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user
1626: agent must run the following steps:
1627:
1628: <ol>
1629: <li>
1630: <p><span title="resolve a url">Resolve</span> the <var title="">url</var>
1631: argument.
1632:
1633: <li>
1634: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
1635:
1636: <li>
1637: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
1638: is not the <span title="same origin">same</span> as the origin of the
1639: script that invoked the method, then throw a <span>security
1640: exception</span>.
1641:
1642: <li>
1643: <p>Attempt to <span>fetch</span><!-- XXX --> the resource identified by
1644: the resulting <span>absolute URL</span>.</p>
1645:
1646: <p>If the attempt fails, return false and abort these steps.</p>
1647:
1648: <p>If the attempt succeeds, then let <var title="">script</var> be the
1649: resource that was obtained.</p>
1650:
1651: <p class=note>As with the initial script, the script here is always
1652: assumed to be JavaScript, regardless of the MIME type.</p>
1653: <!-- XXX -->
1654:
1655: <li>
1656: <p>Let <var title="">script</var>'s <span>script execution
1657: context</span>, <span>script browsing context</span>, and <span>script
1658: document context</span> be the same as for the script that was executed
1659: by the <a href="#run-a">run a worker</a> processing model for this
1660: worker.</p>
1661:
1662: <li>
1663: <p>Run <var title="">script</var> until it either returns, fails to catch
1664: an exception, or gets prematurely aborted by the "<a href="#kill-a">kill
1665: a worker</a>" algorithm above.</p>
1666:
1667: <p>If an exception was raised or if the script was prematurely aborted,
1668: then abort these steps, letting the exception or aborting continue to be
1669: processed by the script that called the <code
1.27 ihickson 1670: title=dom-WorkerGlobalScope-importScript><a
1671: href="#importscript">importScript()</a></code> method.</p>
1.26 ihickson 1672:
1673: <p>Otherwise, return true.</p>
1674: </ol>
1675:
1676: <h3 id=apis-defined><span class=secno>3.2 </span>APIs defined in other
1677: specifications</h3>
1678:
1.27 ihickson 1679: <p>The <dfn id=localstorage
1.26 ihickson 1680: title=dom-localStorage><code>localStorage</code></dfn>, <dfn
1681: id=opendatabase title=dom-opendatabase><code>openDatabase()</code></dfn>
1682: must act as defined for the APIs with the same names on the
1683: <code>Window</code> object in the HTML5 specification, with the exception
1684: that where the API would use the <span>origin</span> of the <span>active
1685: document</span> of the <span>browsing context</span> of the
1686: <code>Window</code> object on which the method was supposedly invoked, it
1687: must instead use the <span>origin</span> of the script that invoked the
1688: method. <a href="#refsHTML5">[HTML5]</a>
1689:
1690: <p>The <dfn id=shownotification
1691: title=dom-showNotification><code>showNotification()</code></dfn> methods
1692: must act as defined for the APIs with the same names on the
1693: <code>Window</code> object in the HTML5 specification. <a
1694: href="#refsHTML5">[HTML5]</a>
1695:
1696: <h3 id=interface><span class=secno>3.3 </span>Interface objects and
1697: constructors</h3>
1698:
1699: <p>There must be no interface objects and constructors available in the
1700: global scope of scripts whose <span>script execution context</span> is a
1701: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
1702: except for the following:
1703:
1704: <ul>
1705: <li>
1706: <p><code>XMLHttpRequest</code> and all interface objects and constructors
1707: defined by the XMLHttpRequest specifications, except that the
1708: <span>document response entity body</span> must always be null. <a
1709: href="#refsXHR">[XHR]</a>
1710:
1711: <li>
1712: <p>The <code>WebSocket</code> interface object and constructor.
1713:
1714: <li>
1715: <p>The <code>MessageChannel</code> interface object and constructor.
1716: </ul>
1717:
1.34 ihickson 1718: <h3 id=worker0><span class=secno>3.4 </span>Worker locations</h3>
1719:
1720: <pre
1721: class=idl>[NoInterfaceObject] interface <dfn id=workerlocation>WorkerLocation</dfn> {
1722: readonly attribute DOMString <a href="#href" title=dom-WorkerLocation-href>href</a>;
1723: readonly attribute DOMString <a href="#protocol" title=dom-WorkerLocation-protocol>protocol</a>;
1724: readonly attribute DOMString <a href="#host" title=dom-WorkerLocation-host>host</a>;
1725: readonly attribute DOMString <a href="#hostname" title=dom-WorkerLocation-hostname>hostname</a>;
1726: readonly attribute DOMString <a href="#port0" title=dom-WorkerLocation-port>port</a>;
1727: readonly attribute DOMString <a href="#pathname" title=dom-WorkerLocation-pathname>pathname</a>;
1728: readonly attribute DOMString <a href="#search" title=dom-WorkerLocation-search>search</a>;
1729: readonly attribute DOMString <a href="#hash" title=dom-WorkerLocation-hash>hash</a>;
1730: };</pre>
1731:
1732: <p>A <code><a href="#workerlocation">WorkerLocation</a></code> object
1733: represents an <span>absolute URL</span> set at its creation.
1734:
1735: <p>The <dfn id=href title=dom-WorkerLocation-href><code>href</code></dfn>
1736: attribute must return the <span>absolute URL</span> that the object
1737: represents.
1738:
1739: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface
1740: also has the complement of <span>URL decomposition attributes</span>, <dfn
1741: id=protocol title=dom-WorkerLocation-protocol><code>protocol</code></dfn>,
1742: <dfn id=host title=dom-WorkerLocation-host><code>host</code></dfn>, <dfn
1743: id=port0 title=dom-WorkerLocation-port><code>port</code></dfn>, <dfn
1744: id=hostname title=dom-WorkerLocation-hostname><code>hostname</code></dfn>,
1745: <dfn id=pathname
1746: title=dom-WorkerLocation-pathname><code>pathname</code></dfn>, <dfn
1747: id=search title=dom-WorkerLocation-search><code>search</code></dfn>, and
1748: <dfn id=hash title=dom-WorkerLocation-hash><code>hash</code></dfn>. These
1749: must follow the rules given for URL decomposition attributes, with the
1750: <span title=concept-uda-input>input</span> being the <span>absolute
1751: URL</span> that the object represents (same as the <code
1752: title=dom-WorkerLocation-href><a href="#href">href</a></code> attribute),
1753: and the <span title=concept-uda-setter>common setter action</span> being a
1754: no-op, since the attributes are defined to be readonly. <a
1755: href="#refsHTML5">[HTML5]</a>
1756:
1.1 ihickson 1757: <h2 class=no-num id=references>References</h2>
1758:
1759: <p class=big-issue>This section will be written in a future
1760: draft.<!--XXX-->
1761:
1762: <h2 class=no-num id=acknowledgements>Acknowledgements</h2>
1763: <!-- ACKS -->
1764:
1.26 ihickson 1765: <p>Thanks to Aaron Boodman, Jonas Sicking, Maciej Stachowiak, Mike Smith,
1766: and Philip Taylor for their useful and substantial comments.
1.4 ihickson 1767:
1768: <p>Huge thanks to the whole Gears team, who pioneered this technology and
1769: whose experience has been a huge influence on this specification.
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