Annotation of html5/workers/Overview.html, revision 1.36
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
1.26 ihickson 22: Draft <!--ZZZ--> 6 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
1.26 ihickson 147: the W3C Recommendation track. <!--ZZZ:--> This specification is the 6
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:
198: <li><a href="#granting"><span class=secno>1.1.5 </span>Granting
199: capabilities</a>
200:
201: <li><a href="#delegation"><span class=secno>1.1.6
202: </span>Delegation</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>
287: <title>Worker example: Computation</title>
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');
347: var database = utils.openDatabase('demobase', '1.0', 'Demo Database', 10240);
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
! 766: <code title=dom-WorkerGlobalScope-port><a href="#port">port global
! 767: variable in the worker, the script uses the <code
! 768: title=handler-WorkerGlobalScope-onconnect>onconnect</code> event listener
! 769: to listen for multiple connections.</a></code>
! 770:
! 771: <p><strong>Direct channels</strong>. When the worker receives a "msg"
! 772: message from one viewer naming another viewer, it sets up a direct
! 773: connection between the two, so that the two viewers can communicate
! 774: directly without the worker having to proxy all the messages.
! 775:
! 776: <p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View
! 777: this example online</a>.
1.34 ihickson 778:
779: <h4 id=granting><span class=secno>1.1.5 </span>Granting capabilities</h4>
780:
1.36 ! ihickson 781: <p><em>This section is non-normative.</em>
! 782:
1.35 ihickson 783: <p class=big-issue>...
1.34 ihickson 784:
785: <h4 id=delegation><span class=secno>1.1.6 </span>Delegation</h4>
786:
1.36 ! ihickson 787: <p><em>This section is non-normative.</em>
! 788:
1.35 ihickson 789: <p class=big-issue>...
1.34 ihickson 790:
1.22 ihickson 791: <h3 id=conformance><span class=secno>1.2 </span>Conformance requirements</h3>
1.1 ihickson 792:
793: <p>All diagrams, examples, and notes in this specification are
794: non-normative, as are all sections explicitly marked non-normative.
795: Everything else in this specification is normative.
796:
797: <p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
798: NOT",-->
799: "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the
800: normative parts of this document are to be interpreted as described in
801: RFC2119. For readability, these words do not appear in all uppercase
802: letters in this specification. <a href="#refsRFC2119">[RFC2119]</a></p>
803: <!-- XXX but they should be
804: marked up -->
805:
806: <p>Requirements phrased in the imperative as part of algorithms (such as
807: "strip any leading space characters" or "return false and abort these
808: steps") are to be interpreted with the meaning of the key word ("must",
809: "should", "may", etc) used in introducing the algorithm.
810:
811: <p>Some conformance requirements are phrased as requirements on attributes,
812: methods or objects. Such requirements are to be interpreted as
813: requirements on user agents.
814:
815: <p>Conformance requirements phrased as algorithms or specific steps may be
816: implemented in any manner, so long as the end result is equivalent. (In
817: particular, the algorithms defined in this specification are intended to
818: be easy to follow, and not intended to be performant.)
819:
820: <p>The only conformance class defined by this specification is user agents.
821:
822: <p>User agents may impose implementation-specific limits on otherwise
823: unconstrained inputs, e.g. to prevent denial of service attacks, to guard
824: against running out of memory, or to work around platform-specific
825: limitations.
826:
1.22 ihickson 827: <h4 id=dependencies><span class=secno>1.2.1 </span>Dependencies</h4>
1.1 ihickson 828:
829: <p>This specification relies on several other underlying specifications.
830:
831: <dl>
832: <dt>HTML5
833:
834: <dd>
835: <p>Many fundamental concepts from HTML5 are used by this specification.
836: <a href="#refsHTML5">[HTML5]</a></p>
837:
838: <dt>ECMAScript
839:
840: <dd>
841: <p>This specification is intended to be used with JavaScript as the
842: scripting language. <a href="#refsJS">[JS]</a></p>
843:
844: <dt>WebIDL
845:
846: <dd>
847: <p>The IDL blocks in this specification use the semantics of the WebIDL
848: specification. <a href="#refsWebIDL">[WebIDL]</a></p>
849: </dl>
850:
1.22 ihickson 851: <h3 id=terminology><span class=secno>1.3 </span>Terminology</h3>
1.1 ihickson 852:
853: <p>For simplicity, terms such as <em>shown</em>, <em>displayed</em>, and
854: <em>visible</em> might sometimes be used when referring to the way a
855: document is rendered to the user. These terms are not meant to imply a
856: visual medium; they must be considered to apply to other media in
857: equivalent ways.
858:
1.4 ihickson 859: <p>The construction "a <code title="">Foo</code> object", where <code
860: title="">Foo</code> is actually an interface, is sometimes used instead of
861: the more accurate "an object implementing the interface <code
862: title="">Foo</code>".
1.1 ihickson 863:
864: <p>The term DOM is used to refer to the API set made available to scripts
865: in Web applications, and does not necessarily imply the existence of an
866: actual <code>Document</code> object or of any other <code>Node</code>
867: objects as defined in the DOM Core specifications. <a
868: href="#refsDOM3CORE">[DOM3CORE]</a>
869:
870: <p>A DOM attribute is said to be <em>getting</em> when its value is being
871: retrieved (e.g. by author script), and is said to be <em>setting</em> when
872: a new value is assigned to it.
873:
874: <p>If a DOM object is said to be <dfn id=live>live</dfn>, then that means
875: that any attributes returning that object must always return the same
876: object (not a new object each time), and the attributes and methods on
877: that object must operate on the actual underlying data, not a snapshot of
878: the data.
879:
1.12 ihickson 880: <h2 id=infrastructure><span class=secno>2. </span>Infrastructure</h2>
1.4 ihickson 881:
1.26 ihickson 882: <h3 id=the-workerglobalscope><span class=secno>2.1 </span>The <code><a
883: href="#workerglobalscope">WorkerGlobalScope</a></code> interface</h3>
1.4 ihickson 884:
885: <pre
1.26 ihickson 886: class=idl>[NoInterfaceObject] interface <dfn id=workerglobalscope>WorkerGlobalScope</dfn> {
887: // core worker features
888: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#self" title=dom-WorkerGlobalScope-self>self</a>;
1.34 ihickson 889: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#location" title=dom-WorkerGlobalScope-location>location</a>;
1.26 ihickson 890: readonly attribute DOMString <a href="#name" title=dom-WorkerGlobalScope-name>name</a>;
891: readonly attribute boolean <a href="#closing" title=dom-WorkerGlobalScope-closing>closing</a>;
892: void <a href="#close" title=dom-WorkerGlobalScope-close>close</a>();
893:
894: // other APIs
895: readonly attribute WorkerUtils <a href="#utils" title=dom-WorkerGlobalScope-utils>utils</a>;
1.9 ihickson 896:
897: // event handler attributes
1.26 ihickson 898: attribute <span>EventListener</span> <a href="#onconnect" title=handler-WorkerGlobalScope-onconnect>onconnect</a>;
899: attribute <span>EventListener</span> <a href="#onunload" title=handler-WorkerGlobalScope-onunload>onunload</a>;
1.4 ihickson 900: };</pre>
901:
1.26 ihickson 902: <p>The <dfn id=self
903: title=dom-WorkerGlobalScope-self><code>self</code></dfn> attribute must
904: return the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
905: object itself.
1.9 ihickson 906:
1.34 ihickson 907: <p>The <dfn id=location
908: title=dom-WorkerGlobalScope-location><code>location</code></dfn> attribute
909: must return the <code><a href="#workerlocation">WorkerLocation</a></code>
910: object created for the <code><a
911: href="#workerglobalscope">WorkerGlobalScope</a></code> object when the
912: worker was created. It represents the <span>absolute URL</span> of the
913: script that was used to initialize the worker.
1.26 ihickson 914:
915: <p>The <dfn id=name
916: title=dom-WorkerGlobalScope-name><code>name</code></dfn> attribute must
917: return the value it was assigned when the <code><a
918: href="#workerglobalscope">WorkerGlobalScope</a></code> object was created
919: by the "<a href="#run-a">run a worker</a>" algorithm. If it has a value
920: that isn't the empty string, its value represents the name that can be
921: used to obtain a reference to the worker using the <code
922: title=dom-WorkerFactory-createNamedWorker><a
1.11 ihickson 923: href="#createnamedworker">createNamedWorker()</a></code> method.
1.6 ihickson 924:
1.4 ihickson 925: <p>The <dfn id=closing
1.26 ihickson 926: title=dom-WorkerGlobalScope-closing><code>closing</code></dfn> attribute
927: must return false until it is set to true by one of the algorithms in the
1.19 ihickson 928: processing model section below.
1.4 ihickson 929:
1.9 ihickson 930: <p>The following are the <span>event handler DOM attributes</span> that
931: must be supported by objects implementing the <code><a
1.26 ihickson 932: href="#workerglobalscope">WorkerGlobalScope</a></code> interface:
1.9 ihickson 933:
934: <dl>
1.20 ihickson 935: <dt><dfn id=onconnect
1.26 ihickson 936: title=handler-WorkerGlobalScope-onconnect><code>onconnect</code></dfn>
1.9 ihickson 937:
938: <dd>
939: <p>Must be invoked whenever a <code
1.26 ihickson 940: title=event-WorkerGlobalScope-connect>connect</code> event is targeted
941: at or bubbles through the <code><a
942: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.9 ihickson 943:
944: <dt><dfn id=onunload
1.26 ihickson 945: title=handler-WorkerGlobalScope-onunload><code>onunload</code></dfn>
1.9 ihickson 946:
947: <dd>
948: <p>Must be invoked whenever a <code title=event-unload>unload</code>
949: event is targeted at or bubbles through the <code><a
1.26 ihickson 950: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.9 ihickson 951: </dl>
952:
1.26 ihickson 953: <p>The <dfn id=utils
954: title=dom-WorkerGlobalScope-utils><code>utils</code></dfn> attribute must
955: return the <code><a href="#workerutils">WorkerUtils</a></code> object
956: created for the <code><a
957: href="#workerglobalscope">WorkerGlobalScope</a></code> object when the
958: worker was created.
959:
1.30 ihickson 960: <p>In addition to the above members, the <a href="#success" title="worker
961: creation succeeded">worker creation success steps</a> add a <dfn id=port
962: title=dom-WorkerGlobalScope-port><code>port</code></dfn> property to the
963: object.
964:
1.15 ihickson 965: <h3 id=base-urls><span class=secno>2.2 </span>Base URLs and origins of
966: workers</h3>
967:
968: <p>The <span>base URL</span> of a <span>URL</span> passed to an API in a
1.34 ihickson 969: worker is the <span>absolute URL</span> given that the worker's <code
970: title=dom-WorkerGlobalScope-location><a
971: href="#location">location</a></code> attribute represents.
1.15 ihickson 972:
1.25 ihickson 973: <p>Both the <span>origin</span> and <span>effective script origin</span> of
974: scripts running in workers are the <span>origin</span> of the
1.34 ihickson 975: <span>absolute URL</span> given that the worker's <code
976: title=dom-WorkerGlobalScope-location><a
977: href="#location">location</a></code> attribute represents.
1.15 ihickson 978:
979: <h3 id=the-queue><span class=secno>2.3 </span>The queue of events</h3>
1.4 ihickson 980:
1.26 ihickson 981: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
982: object is asssociated with a <dfn id=queue>queue of events</dfn>, which is
983: initially empty.
1.4 ihickson 984:
985: <p>An event in the queue can be a DOM event or a timeout callback.
986:
1.8 ihickson 987: <p>All asynchronous callbacks and events that would be called or dispatched
988: in the worker must be added to the worker's queue, with the "<a
989: href="#run-a">run a worker</a>" processing model below taking care of
990: actually calling the callbacks or dispatching the events.
991:
1.26 ihickson 992: <p>Once the <code><a
993: href="#workerglobalscope">WorkerGlobalScope</a></code>'s <code
994: title=dom-WorkerGlobalScope-closing><a href="#closing">closing</a></code>
1.8 ihickson 995: attribute is set to true, the queue must discard anything else that would
996: be added to it. Effectively, once the <code
1.26 ihickson 997: title=dom-WorkerGlobalScope-closing><a href="#closing">closing</a></code>
1.8 ihickson 998: attribute is true, timers stop firing, notifications for all pending
999: asynchronous operations are dropped, etc.
1000:
1.15 ihickson 1001: <h3 id=the-workers><span class=secno>2.4 </span>The worker's ports</h3>
1.9 ihickson 1002:
1003: <p>Workers communicate with other workers and with <span title="browsing
1004: context">browsing contexts</span> through <span title="channel
1005: messaging">message channels</span> and their <code>MessagePort</code>
1006: objects.
1007:
1.26 ihickson 1008: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1009: <var title="">worker</var> has a list of <dfn id=the-workers0>the worker's
1.9 ihickson 1010: ports</dfn>, which consists of all the <code>MessagePort</code> objects
1011: that are entangled with another port and that have one (but only one) port
1.26 ihickson 1012: owned by <var title="">worker</var>. This list includes all the
1013: <code>MessagePort</code> objects that are in events pending in the <a
1014: href="#queue">queue of events</a>.
1.9 ihickson 1015:
1.17 ihickson 1016: <hr>
1017:
1018: <p>A worker is said to be a <dfn id=front-line>front-line worker</dfn> if
1019: at least one of the <a href="#the-workers0">the worker's ports</a> has an
1.26 ihickson 1020: entangled <code>MessagePort</code> owned by a <code>Window</code> object.
1.17 ihickson 1021:
1022: <p>A worker is said to be a <dfn id=needed>needed worker</dfn> if either:
1023:
1024: <ul>
1025: <li>it is a <a href="#front-line">front-line worker</a>, or
1026:
1027: <li>at least one of the <a href="#the-workers0">the worker's ports</a> has
1.26 ihickson 1028: an entangled <code>MessagePort</code> owned by a <code><a
1029: href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
1030: itself a <a href="#needed">needed worker</a>.
1.17 ihickson 1031: </ul>
1032:
1033: <hr>
1034:
1035: <p>A worker is said to be an <dfn id=active>active front-line worker</dfn>
1.28 ihickson 1036: if at least one of the <a href="#the-workers0">the worker's ports</a> is
1037: entangled with a <code>MessagePort</code> <var title="">p</var> whose
1038: owner is a <code>Window</code> object whose <span>active document</span>
1039: is the <code>Document</code> that was that <span>browsing context</span>'s
1040: <span>active document</span> when that <code>MessagePort</code> <var
1041: title="">p</var> was created, and that <code>Document</code> is
1042: <span>fully active</span>.
1.17 ihickson 1043:
1044: <p>A worker is said to be an <dfn id=active0>active needed worker</dfn> if
1045: either:
1046:
1047: <ul>
1048: <li>it is an <a href="#active">active front-line worker</a>, or
1049:
1050: <li>at least one of the <a href="#the-workers0">the worker's ports</a> has
1.26 ihickson 1051: an entangled <code>MessagePort</code> owned by a <code><a
1052: href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
1053: itself an <a href="#active0">active needed worker</a>.
1.17 ihickson 1054: </ul>
1055:
1.15 ihickson 1056: <h3 id=processing><span class=secno>2.5 </span>Processing model</h3>
1.4 ihickson 1057:
1.6 ihickson 1058: <p>When a user agent is to <dfn id=run-a>run a worker</dfn> named <var
1.7 ihickson 1059: title="">name</var> for a script with <span>URL</span> <var
1060: title="">url</var>, a browsing context <var title="">owner browsing
1061: context</var> and a <code>Document</code> <var title="">owner
1062: document</var>, it must run the following steps in a completely separate
1063: and parallel execution environment:
1.4 ihickson 1064:
1065: <ol>
1066: <li>
1.7 ihickson 1067: <p>Attempt to <span>fetch</span><!-- XXX --> the resource identified by
1068: <var title="">url</var>.</p>
1069:
1070: <p>If the attempt fails, then abort these steps and invoke the <a
1.34 ihickson 1071: href="#worker1" title="worker creation failed">error handling steps</a>
1.7 ihickson 1072: defined by the algorithm that called this one.</p>
1073:
1074: <p>If the attempt succeeds, then let <var title="">script</var> be the
1075: resource that was obtained.</p>
1076:
1077: <p class=note>As with <code>script</code> elements, the MIME type of the
1078: script is ignored. Unlike with <code>script</code> elements, there is no
1079: way to override the type. It's always assumed to be JavaScript.</p>
1080: <!-- XXX people will complain about
1081: this. I guess we might want to examine the MIME type... -->
1082:
1083:
1084: <li>
1.26 ihickson 1085: <p>Create a new <code><a
1086: href="#workerglobalscope">WorkerGlobalScope</a></code> object, <var
1087: title="">worker</var>.</p>
1.4 ihickson 1088:
1089: <li>
1.26 ihickson 1090: <p>Set the <code title=dom-WorkerGlobalScope-name><a
1.19 ihickson 1091: href="#name">name</a></code> attribute of <var title="">worker</var> to
1.6 ihickson 1092: the value of <var title="">name</var>.</p>
1093:
1094: <li>
1.34 ihickson 1095: <p>Create a new <code><a href="#workerlocation">WorkerLocation</a></code>
1096: object for the <code title=dom-WorkerGlobalScope-location><a
1097: href="#location">location</a></code> attribute of <var
1098: title="">worker</var>, representing <var title="">url</var>.</p>
1099:
1100: <li>
1.26 ihickson 1101: <p>Create a new <code><a href="#workerutils">WorkerUtils</a></code>
1102: object for the <code title=dom-WorkerGlobalScope-utils><a
1.34 ihickson 1103: href="#utils">utils</a></code> attribute of <var title="">worker</var>.</p>
1.26 ihickson 1104:
1105: <li>
1.4 ihickson 1106: <p>Let <var title="">script</var>'s <span>script execution context</span>
1107: (and thus also <span>global object</span>) be <var
1.19 ihickson 1108: title="">worker</var>.</p>
1.4 ihickson 1109:
1110: <li>
1111: <p>Let <var title="">script</var>'s <span>script browsing context</span>
1112: be <var title="">owner browsing context</var>.</p>
1113:
1114: <li>
1115: <p>Let <var title="">script</var>'s <span>script document context</span>
1116: be <var title="">owner document</var>.</p>
1117:
1118: <li>
1.9 ihickson 1119: <p>Invoke the <a href="#success" title="worker creation
1120: succeeded">success steps</a> defined by the algorithm that called this
1.17 ihickson 1121: one.</p>
1122:
1123: <p class=note>This will usually add an event to the <a
1.28 ihickson 1124: href="#queue">queue of events</a> and set the <code
1.30 ihickson 1125: title=dom-WorkerGlobalScope-port><a href="#port">port</a></code>
1126: property on the <var title="">worker</var> object. If it does, that
1127: event will have a <code>MessagePort</code> and thus the list of <a
1.17 ihickson 1128: href="#the-workers0">the worker's ports</a> will not be empty. If it
1.19 ihickson 1129: doesn't, then the next step will set the <var title="">worker</var>
1.26 ihickson 1130: object's <code title=dom-WorkerGlobalScope-closing><a
1.17 ihickson 1131: href="#closing">closing</a></code> attribute to true.</p>
1132:
1133: <li>
1.28 ihickson 1134: <p><strong>Closing orphan workers</strong>: Start monitoring <var
1135: title="">worker</var>, such that as soon as the worker stops being a <a
1136: href="#needed">needed worker</a>, the <var title="">worker</var>
1137: object's <code title=dom-WorkerGlobalScope-closing><a
1.17 ihickson 1138: href="#closing">closing</a></code> attribute is set to true.</p>
1.9 ihickson 1139:
1140: <li>
1.28 ihickson 1141: <p><strong>Suspending workers</strong>: Start monitoring <var
1142: title="">worker</var>, such that whenever the <var title="">worker</var>
1143: object's <code title=dom-WorkerGlobalScope-closing><a
1.26 ihickson 1144: href="#closing">closing</a></code> attribute is false and the worker is
1145: not an <a href="#active0">active needed worker</a>, the user agent
1146: suspends execution of script in that worker until such time as either
1147: the <code title=dom-WorkerGlobalScope-closing><a
1148: href="#closing">closing</a></code> attribute switches to true or the
1149: worker becomes an <a href="#active0">active needed worker</a>.</p>
1.7 ihickson 1150:
1151: <li>
1152: <p>Run <var title="">script</var> until it either returns, fails to catch
1153: an exception, or gets prematurely aborted by the "<a href="#kill-a">kill
1154: a worker</a>" algorithm below.</p>
1155:
1156: <p class=note>If the script gets aborted by the "<a href="#kill-a">kill a
1157: worker</a>" algorithm, then that same algorithm will cause there to only
1158: be a single event in the <a href="#queue">queue of events</a> at the
1.28 ihickson 1159: next step, namely the <code title=message-unload>unload</code> event.</p>
1.4 ihickson 1160:
1161: <li>
1.9 ihickson 1162: <p><i>Event loop</i>: Wait until either there is an event in the <a
1.4 ihickson 1163: href="#queue">queue of events</a> associated with <var
1.19 ihickson 1164: title="">worker</var> or the <var title="">worker</var> object's <code
1.26 ihickson 1165: title=dom-WorkerGlobalScope-closing><a
1166: href="#closing">closing</a></code> attribute is set to true.</p>
1.4 ihickson 1167:
1168: <li>
1169: <p>Dispatch the oldest event or callback in the <a href="#queue">queue of
1.9 ihickson 1170: events</a>, if any. The handling of this event or the execution of this
1171: callback might get prematurely aborted by the "<a href="#kill-a">kill a
1.8 ihickson 1172: worker</a>" algorithm below.</p>
1.4 ihickson 1173:
1174: <li>
1175: <p>If there are any more events in the <a href="#queue">queue of
1.19 ihickson 1176: events</a> or if the <var title="">worker</var> object's <code
1.26 ihickson 1177: title=dom-WorkerGlobalScope-closing><a
1178: href="#closing">closing</a></code> attribute is set to false, then jump
1179: back to the step above labeled <i>event loop</i>.</p>
1.4 ihickson 1180:
1181: <li>
1182: <p class=big-issue>timers, intervals, XMLHttpRequests, database
1.28 ihickson 1183: transactions, etc, must be killed; ports must be unentangled</p>
1.4 ihickson 1184: </ol>
1185:
1186: <hr>
1187:
1188: <p>When a user agent is to <dfn id=kill-a>kill a worker</dfn>, it must run
1189: the following steps in parallel with the worker's main loop (the "<a
1190: href="#run-a">run a worker</a>" processing model defined above):
1191:
1192: <ol>
1193: <li>
1194: <p>Create an <code>Event</code> object with the event name <code
1195: title=event-unload>unload</code>, which does not bubble and is not
1196: cancelable, and add it to the worker's <code><a
1.26 ihickson 1197: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.8 ihickson 1198: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 1199: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.28 ihickson 1200: </li>
1201: <!-- XXX shouldn't add one if closing is
1202: already true, assuming unload has already been added to the queue
1203: (?) -->
1.4 ihickson 1204:
1205: <li>
1.26 ihickson 1206: <p>Set the worker's <code><a
1207: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code
1208: title=dom-WorkerGlobalScope-closing><a
1.8 ihickson 1209: href="#closing">closing</a></code> attribute to true.
1210:
1211: <li>
1212: <p>Wait a user-agent-defined amount of time. If the "<a href="#run-a">run
1213: a worker</a>" processing model defined above immediately starts running
1.28 ihickson 1214: event listeners registered for the <code
1215: title=event-unload>unload</code> event, this time should not be zero
1216: — the idea is that the <code title=event-unload>unload</code>
1217: event can be used to clean up when shutting down unexpectedly.
1.4 ihickson 1218:
1219: <li>
1220: <p>If there are any events in the <a href="#queue">queue of events</a>
1221: other than the <code title=event-unload>unload</code> event that this
1222: algorithm just added, discard them without dispatching them.
1223:
1224: <li>
1225: <p>If the <code title=event-unload>unload</code> event that this
1226: algorithm just added hasn't yet been dispatched, then abort the script
1227: currently running in the worker.
1228:
1229: <li>
1230: <p>Wait a user-agent-defined amount of time.
1231:
1232: <li>
1233: <p>Abort the script currently running in the worker (if any script is
1234: running, then it will be a handler for the <code
1235: title=event-unload>unload</code> event).
1236: </ol>
1237:
1.19 ihickson 1238: <p>User agents may invoke the "<a href="#kill-a">kill a worker</a>"
1239: processing model on a worker at any time, e.g. in response to user
1240: requests, in response to CPU quota management, or when a worker stops
1241: being a <a href="#needed">needed worker</a> if the worker continues
1.26 ihickson 1242: executing even after its <code title=dom-WorkerGlobalScope-closing><a
1.19 ihickson 1243: href="#closing">closing</a></code> attribute was set to true.
1244:
1.8 ihickson 1245: <hr>
1246:
1247: <p>When a script invokes the <dfn id=close
1.26 ihickson 1248: title=dom-WorkerGlobalScope-close><code>close()</code></dfn> method on a
1249: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object,
1250: the user agent must run the following steps:
1.8 ihickson 1251:
1252: <ol>
1253: <li>
1254: <p>Create an <code>Event</code> object with the event name <code
1255: title=event-unload>unload</code>, which does not bubble and is not
1256: cancelable, and add it to the <code><a
1.26 ihickson 1257: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.8 ihickson 1258: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 1259: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.8 ihickson 1260:
1261: <li>
1.26 ihickson 1262: <p>Set the worker's <code><a
1263: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code
1264: title=dom-WorkerGlobalScope-closing><a
1.8 ihickson 1265: href="#closing">closing</a></code> attribute to true.
1266:
1267: <li>
1268: <p>For each <code>MessagePort</code> object that is entangled with
1.26 ihickson 1269: another port and that has one (but only one) port whose owner is the
1270: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
1271: on which the method was invoked, run the following substeps:</p>
1.8 ihickson 1272:
1273: <ol>
1274: <li>
1275: <p>Unentangle the two ports.
1276:
1277: <li>
1278: <p>At the next available opportunity, after any scripts have finished
1279: executing<!-- XXX queue -->, <span>fire a simple event</span> called
1280: <code title=event-unload>unload</code> at the other port (the one
1.26 ihickson 1281: whose owner is not the <code><a
1282: href="#workerglobalscope">WorkerGlobalScope</a></code> object on which
1283: the <code title=dom-WorkerGlobalScope-close><a
1.8 ihickson 1284: href="#close">close()</a></code> method was called).
1285: </ol>
1286: </ol>
1287:
1.15 ihickson 1288: <h3 id=creating><span class=secno>2.6 </span>Creating workers</h3>
1.5 ihickson 1289:
1290: <pre
1.26 ihickson 1291: class=idl>[NoInterfaceObject] interface <dfn id=workerfactory>WorkerFactory</dfn> {
1292: <span>MessagePort</span> <a href="#createworker" title=dom-WorkerFactory-createWorker>createWorker</a>(in DOMString scriptURL);
1293: <span>MessagePort</span> <a href="#createnamedworker" title=dom-WorkerFactory-createNamedWorker>createNamedWorker</a>(in DOMString name, in DOMString scriptURL);
1.5 ihickson 1294: };</pre>
1295:
1.26 ihickson 1296: <p>Objects that implement the <code>Window</code> and <code><a
1297: href="#workerutils">WorkerUtils</a></code> interfaces must also implement
1298: the <code><a href="#workerfactory">WorkerFactory</a></code> interface.
1.5 ihickson 1299:
1.9 ihickson 1300: <hr>
1301:
1.11 ihickson 1302: <p>When the <dfn id=createworker
1.26 ihickson 1303: title=dom-WorkerFactory-createWorker><code>createWorker(<var
1.11 ihickson 1304: title="">scriptURL</var>)</code></dfn> method is invoked, the user agent
1305: must run the following steps:
1.9 ihickson 1306:
1307: <ol>
1308: <li>
1309: <p><span title="resolve a url">Resolve</span> the <var
1310: title="">scriptURL</var> argument.
1311:
1312: <li>
1313: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
1314:
1315: <li>
1316: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
1317: is not the <span title="same origin">same</span> as the origin of the
1318: script that invoked the method, then throw a <span>security
1319: exception</span>.
1320:
1321: <li>
1322: <p><a href="#create">Create a worker</a> from the resulting
1323: <span>absolute URL</span> whose name is the empty string.
1324:
1325: <li>
1326: <p>Return the <code>MessagePort</code> object returned from the <a
1327: href="#create">create a worker</a> algorithm.
1328: </ol>
1329:
1330: <hr>
1331:
1.11 ihickson 1332: <p>When the <dfn id=createnamedworker
1.26 ihickson 1333: title=dom-WorkerFactory-createNamedWorker><code>createNamedWorker(<var
1.11 ihickson 1334: title="">name</var>, <var title="">scriptURL</var>)</code></dfn> method is
1.9 ihickson 1335: invoked, the user agent must run the following steps:
1336:
1337: <ol>
1338: <li>
1339: <p><span title="resolve a url">Resolve</span> the <var
1340: title="">scriptURL</var> argument.
1.4 ihickson 1341:
1.9 ihickson 1342: <li>
1343: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
1344:
1345: <li>
1346: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
1347: is not the <span title="same origin">same</span> as the origin of the
1348: script that invoked the method, then throw a <span>security
1349: exception</span>.
1350:
1351: <li>
1352: <p>If the <var title="">name</var> argument is the empty string, <a
1353: href="#create">create a worker</a> from the resulting <span>absolute
1354: URL</span>, whose name is the empty string, and return the
1355: <code>MessagePort</code> object returned from the <a
1356: href="#create">create a worker</a> algorithm. Then, abort these steps.
1357:
1358: <li>
1.26 ihickson 1359: <p>If there exists a worker whose <code
1360: title=dom-WorkerGlobalScope-closing><a
1.9 ihickson 1361: href="#closing">closing</a></code> attribute is false, whose <code
1.26 ihickson 1362: title=dom-WorkerGlobalScope-name><a href="#name">name</a></code>
1363: attribute is exactly equal to the <var title="">name</var> argument, and
1.34 ihickson 1364: whose <code title=dom-WorkerGlobalScope-location><a
1365: href="#location">location</a></code> attribute represents an
1366: <span>absolute URL</span> that has the <span>same origin</span> as the
1367: resulting <span>absolute URL</span>, then run these substeps:</p>
1.9 ihickson 1368:
1369: <ol>
1370: <li>
1.34 ihickson 1371: <p>If that worker's <code title=dom-WorkerGlobalScope-location><a
1372: href="#location">location</a></code> attribute represents an
1373: <span>absolute URL</span> that is not exactly equal to the resulting
1374: <span>absolute URL</span>, then throw a <code>URL_MISMATCH_ERR</code>
1375: exception and abort these steps. <span class=big-issue>code 19</span>
1.9 ihickson 1376:
1377: <li>
1378: <p><span>Create a new <code>MessagePort</code> object</span> owned by
1379: the <span>script execution context</span> of the script that invoked
1380: the method.
1381:
1382: <li>
1383: <p>Return that port.
1384:
1385: <li>
1.20 ihickson 1386: <p>Asynchronously, <a href="#connect" title="connect to a
1387: worker">connect</a> to this preexisting worker, with the newly created
1.9 ihickson 1388: port.
1389: </ol>
1390:
1391: <p>Otherwise, <a href="#create">create a worker</a> from the resulting
1392: <span>absolute URL</span>, whose name is the value of the <var
1393: title="">name</var> argument, and return the <code>MessagePort</code>
1394: object returned from the <a href="#create">create a worker</a>
1395: algorithm.</p>
1396: </ol>
1397:
1398: <hr>
1399:
1400: <p>The steps to <dfn id=create>create a worker</dfn> from a
1401: <span>URL</span> <var title="">url</var> and whose name is <var
1402: title="">name</var>, in the context of a method call, are as follows:
1403:
1404: <ol>
1405: <li>
1406: <p><span>Create a new <code>MessagePort</code> object</span> owned by the
1407: <span>script execution context</span> of the script that invoked the
1408: method.
1409:
1410: <li>
1411: <p>Return that port.
1412:
1413: <li>
1414: <p>In a parallel execution context (i.e. a separate thread or process or
1415: equivalent construct), <a href="#run-a">run a worker</a> named <var
1416: title="">name</var> for the script with <span>URL</span> <var
1417: title="">url</var>, with the <span>script browsing context</span> of the
1418: script that invoked the method as the <var title="">owner browsing
1419: context</var> and with the <span>script document context</span> of the
1420: script that invoked the method as the <var title="">owner
1421: document</var>.</p>
1422:
1423: <p>If that algorithm invokes the steps for <dfn id=success title="worker
1.20 ihickson 1424: creation succeeded">success steps</dfn>, then <a href="#connect"
1425: title="connect to a worker">connect</a> to this new worker, with the
1.28 ihickson 1426: newly created port, and if that algorithm returns a second new port,
1.30 ihickson 1427: then add a new property <code title=dom-WorkerGlobalScope-port><a
1428: href="#port">port</a></code> on the new worker's <code><a
1429: href="#workerglobalscope">WorkerGlobalScope</a></code> object, whose
1430: value is the <code>MessagePort</code> object return by the <a
1.28 ihickson 1431: href="#connect">connect to a worker</a> algorithm.</p>
1.9 ihickson 1432:
1.34 ihickson 1433: <p>Otherwise, if the <dfn id=worker1>worker creation failed</dfn>, then
1.33 ihickson 1434: at the next available opportunity, after any scripts have finished
1.9 ihickson 1435: executing<!-- XXX queue -->, <span>fire a simple event</span> called
1436: <code title=event-error>error</code> at the newly created port.</p>
1437: </ol>
1438:
1439: <hr>
1440:
1.20 ihickson 1441: <p>The steps to <dfn id=connect>connect to a worker</dfn> given a
1.9 ihickson 1442: <code>MessagePort</code> object <var title="">port</var> are as follows:
1443:
1444: <ol>
1445: <li>
1446: <p>If <var title="">port</var> would have been garbage collected, or if
1.26 ihickson 1447: the <span>active document</span> of the owner of <var
1.9 ihickson 1448: title="">port</var> is no longer the same <code>Document</code> object
1449: as when <var title="">port</var> was created, then do nothing. Abort
1450: these steps. If the worker was just created, it'll get killed
1451: immediately.</p>
1452:
1453: <li>
1454: <p><span>Create a new <code>MessagePort</code> object</span> owned by the
1.26 ihickson 1455: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> of the
1456: worker.
1.9 ihickson 1457:
1458: <li>
1459: <p><span>Entangle</span> this newly created port and the port <var
1460: title="">port</var> that was passed to these steps.
1461:
1462: <li>
1463: <p>At the next available opportunity, after any scripts have finished
1464: executing<!-- XXX queue -->, <span>fire a simple event</span> called
1465: <code title=event-load>load</code> at <var title="">port</var>.
1466:
1467: <li>
1468: <p>Create an event that uses the <code>MessageEvent</code> interface,
1.20 ihickson 1469: with the name <code title=event-connect>connect</code>, which does not
1.9 ihickson 1470: bubble, is cancelable, has no default action, has a <code
1471: title=dom-MessageEvent-data>data</code> attribute whose value is the
1472: empty string and has a <code
1473: title=dom-MessageEvent-messagePort>messagePort</code> attribute whose
1474: value is the newly created port, and add it to the worker's <code><a
1.26 ihickson 1475: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.9 ihickson 1476: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 1477: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.28 ihickson 1478:
1479: <li>
1480: <p>Return the newly created port.
1.9 ihickson 1481: </ol>
1.7 ihickson 1482:
1.12 ihickson 1483: <h2 id=apis-available><span class=secno>3. </span>APIs available to workers</h2>
1484:
1.26 ihickson 1485: <pre
1486: class=idl>[NoInterfaceObject] interface <dfn id=workerutils>WorkerUtils</dfn> {
1.27 ihickson 1487: boolean <a href="#importscript" title=dom-WorkerGlobalScope-importScript>importScript</a>(in DOMString url);
1.26 ihickson 1488: readonly attribute <span>Storage</span> <a href="#localstorage" title=dom-localStorage>localStorage</a>;
1489: <span>Database</span> <a href="#opendatabase" title=dom-opendatabase>openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize);
1490: void <a href="#shownotification" title=dom-showNotification>showNotification</a>(in DOMString title, in DOMString subtitle, in DOMString description);
1491: void <a href="#shownotification" title=dom-showNotification>showNotification</a>(in DOMString title, in DOMString subtitle, in DOMString description, in VoidCallback onclick);
1492: };</pre>
1.18 ihickson 1493:
1.12 ihickson 1494: <p>Objects that implement the <code><a
1.26 ihickson 1495: href="#workerutils">WorkerUtils</a></code> interface must also implement
1.12 ihickson 1496: the following interfaces:
1497:
1498: <ul>
1.26 ihickson 1499: <li>The <code>WindowTimers</code> interface
1.12 ihickson 1500:
1.26 ihickson 1501: <li>The <code>EventTarget</code> interface
1.12 ihickson 1502:
1.26 ihickson 1503: <li>The <code><a href="#workerfactory">WorkerFactory</a></code> interface,
1504: as noted earlier in this specification
1.12 ihickson 1505: </ul>
1506:
1.23 ihickson 1507: <p class=big-issue>Need to define a sync database API.
1508:
1509: <p class=big-issue>May need to define a browser sniffing API (like
1510: window.navigator).</p>
1.18 ihickson 1511: <!-- XXX ApplicationCache -->
1512: <!-- XXX a way to set cookies on the URL for the script -->
1.24 ihickson 1513: <!-- XXX debugging: void log(in DOMString s); // log to console -->
1514: <!-- XXX debugging: onerror -->
1.13 ihickson 1515:
1.18 ihickson 1516: <hr>
1.13 ihickson 1517:
1.18 ihickson 1518: <p>The DOM APIs (<code>Node</code> objects, <code>Document</code> objects,
1519: etc) are not available to workers in this version of this specification.
1.13 ihickson 1520:
1.26 ihickson 1521: <h3 id=importing><span class=secno>3.1 </span>Importing scripts and
1522: libraries</h3>
1523:
1.27 ihickson 1524: <p>When a script invokes the <dfn id=importscript
1525: title=dom-WorkerGlobalScope-importScript><code>importScript(<var
1.26 ihickson 1526: title="">url</var>)</code></dfn> method on a <code><a
1527: href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user
1528: agent must run the following steps:
1529:
1530: <ol>
1531: <li>
1532: <p><span title="resolve a url">Resolve</span> the <var title="">url</var>
1533: argument.
1534:
1535: <li>
1536: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
1537:
1538: <li>
1539: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
1540: is not the <span title="same origin">same</span> as the origin of the
1541: script that invoked the method, then throw a <span>security
1542: exception</span>.
1543:
1544: <li>
1545: <p>Attempt to <span>fetch</span><!-- XXX --> the resource identified by
1546: the resulting <span>absolute URL</span>.</p>
1547:
1548: <p>If the attempt fails, return false and abort these steps.</p>
1549:
1550: <p>If the attempt succeeds, then let <var title="">script</var> be the
1551: resource that was obtained.</p>
1552:
1553: <p class=note>As with the initial script, the script here is always
1554: assumed to be JavaScript, regardless of the MIME type.</p>
1555: <!-- XXX -->
1556:
1557: <li>
1558: <p>Let <var title="">script</var>'s <span>script execution
1559: context</span>, <span>script browsing context</span>, and <span>script
1560: document context</span> be the same as for the script that was executed
1561: by the <a href="#run-a">run a worker</a> processing model for this
1562: worker.</p>
1563:
1564: <li>
1565: <p>Run <var title="">script</var> until it either returns, fails to catch
1566: an exception, or gets prematurely aborted by the "<a href="#kill-a">kill
1567: a worker</a>" algorithm above.</p>
1568:
1569: <p>If an exception was raised or if the script was prematurely aborted,
1570: then abort these steps, letting the exception or aborting continue to be
1571: processed by the script that called the <code
1.27 ihickson 1572: title=dom-WorkerGlobalScope-importScript><a
1573: href="#importscript">importScript()</a></code> method.</p>
1.26 ihickson 1574:
1575: <p>Otherwise, return true.</p>
1576: </ol>
1577:
1578: <h3 id=apis-defined><span class=secno>3.2 </span>APIs defined in other
1579: specifications</h3>
1580:
1.27 ihickson 1581: <p>The <dfn id=localstorage
1.26 ihickson 1582: title=dom-localStorage><code>localStorage</code></dfn>, <dfn
1583: id=opendatabase title=dom-opendatabase><code>openDatabase()</code></dfn>
1584: must act as defined for the APIs with the same names on the
1585: <code>Window</code> object in the HTML5 specification, with the exception
1586: that where the API would use the <span>origin</span> of the <span>active
1587: document</span> of the <span>browsing context</span> of the
1588: <code>Window</code> object on which the method was supposedly invoked, it
1589: must instead use the <span>origin</span> of the script that invoked the
1590: method. <a href="#refsHTML5">[HTML5]</a>
1591:
1592: <p>The <dfn id=shownotification
1593: title=dom-showNotification><code>showNotification()</code></dfn> methods
1594: must act as defined for the APIs with the same names on the
1595: <code>Window</code> object in the HTML5 specification. <a
1596: href="#refsHTML5">[HTML5]</a>
1597:
1598: <h3 id=interface><span class=secno>3.3 </span>Interface objects and
1599: constructors</h3>
1600:
1601: <p>There must be no interface objects and constructors available in the
1602: global scope of scripts whose <span>script execution context</span> is a
1603: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
1604: except for the following:
1605:
1606: <ul>
1607: <li>
1608: <p><code>XMLHttpRequest</code> and all interface objects and constructors
1609: defined by the XMLHttpRequest specifications, except that the
1610: <span>document response entity body</span> must always be null. <a
1611: href="#refsXHR">[XHR]</a>
1612:
1613: <li>
1614: <p>The <code>WebSocket</code> interface object and constructor.
1615:
1616: <li>
1617: <p>The <code>MessageChannel</code> interface object and constructor.
1618: </ul>
1619:
1.34 ihickson 1620: <h3 id=worker0><span class=secno>3.4 </span>Worker locations</h3>
1621:
1622: <pre
1623: class=idl>[NoInterfaceObject] interface <dfn id=workerlocation>WorkerLocation</dfn> {
1624: readonly attribute DOMString <a href="#href" title=dom-WorkerLocation-href>href</a>;
1625: readonly attribute DOMString <a href="#protocol" title=dom-WorkerLocation-protocol>protocol</a>;
1626: readonly attribute DOMString <a href="#host" title=dom-WorkerLocation-host>host</a>;
1627: readonly attribute DOMString <a href="#hostname" title=dom-WorkerLocation-hostname>hostname</a>;
1628: readonly attribute DOMString <a href="#port0" title=dom-WorkerLocation-port>port</a>;
1629: readonly attribute DOMString <a href="#pathname" title=dom-WorkerLocation-pathname>pathname</a>;
1630: readonly attribute DOMString <a href="#search" title=dom-WorkerLocation-search>search</a>;
1631: readonly attribute DOMString <a href="#hash" title=dom-WorkerLocation-hash>hash</a>;
1632: };</pre>
1633:
1634: <p>A <code><a href="#workerlocation">WorkerLocation</a></code> object
1635: represents an <span>absolute URL</span> set at its creation.
1636:
1637: <p>The <dfn id=href title=dom-WorkerLocation-href><code>href</code></dfn>
1638: attribute must return the <span>absolute URL</span> that the object
1639: represents.
1640:
1641: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface
1642: also has the complement of <span>URL decomposition attributes</span>, <dfn
1643: id=protocol title=dom-WorkerLocation-protocol><code>protocol</code></dfn>,
1644: <dfn id=host title=dom-WorkerLocation-host><code>host</code></dfn>, <dfn
1645: id=port0 title=dom-WorkerLocation-port><code>port</code></dfn>, <dfn
1646: id=hostname title=dom-WorkerLocation-hostname><code>hostname</code></dfn>,
1647: <dfn id=pathname
1648: title=dom-WorkerLocation-pathname><code>pathname</code></dfn>, <dfn
1649: id=search title=dom-WorkerLocation-search><code>search</code></dfn>, and
1650: <dfn id=hash title=dom-WorkerLocation-hash><code>hash</code></dfn>. These
1651: must follow the rules given for URL decomposition attributes, with the
1652: <span title=concept-uda-input>input</span> being the <span>absolute
1653: URL</span> that the object represents (same as the <code
1654: title=dom-WorkerLocation-href><a href="#href">href</a></code> attribute),
1655: and the <span title=concept-uda-setter>common setter action</span> being a
1656: no-op, since the attributes are defined to be readonly. <a
1657: href="#refsHTML5">[HTML5]</a>
1658:
1.1 ihickson 1659: <h2 class=no-num id=references>References</h2>
1660:
1661: <p class=big-issue>This section will be written in a future
1662: draft.<!--XXX-->
1663:
1664: <h2 class=no-num id=acknowledgements>Acknowledgements</h2>
1665: <!-- ACKS -->
1666:
1.26 ihickson 1667: <p>Thanks to Aaron Boodman, Jonas Sicking, Maciej Stachowiak, Mike Smith,
1668: and Philip Taylor for their useful and substantial comments.
1.4 ihickson 1669:
1670: <p>Huge thanks to the whole Gears team, who pioneered this technology and
1671: whose experience has been a huge influence on this specification.
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