Annotation of html5/workers/Overview.html, revision 1.333
1.327 ihickson 1: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html lang="en-US-x-Hixie"><title>Web Workers</title><style type="text/css">
1.82 ihickson 2: pre { margin-left: 2em; white-space: pre-wrap; }
3: h2 { margin: 3em 0 1em 0; }
4: h3 { margin: 2.5em 0 1em 0; }
5: h4 { margin: 2.5em 0 0.75em 0; }
6: h5, h6 { margin: 2.5em 0 1em; }
7: h1 + h2, h1 + h2 + h2 { margin: 0.75em 0 0.75em; }
8: h2 + h3, h3 + h4, h4 + h5, h5 + h6 { margin-top: 0.5em; }
9: p { margin: 1em 0; }
10: hr:not(.top) { display: block; background: none; border: none; padding: 0; margin: 2em 0; height: auto; }
11: dl, dd { margin-top: 0; margin-bottom: 0; }
12: dt { margin-top: 0.75em; margin-bottom: 0.25em; clear: left; }
13: dt + dt { margin-top: 0; }
14: dd dt { margin-top: 0.25em; margin-bottom: 0; }
15: dd p { margin-top: 0; }
16: dd dl + p { margin-top: 1em; }
17: dd table + p { margin-top: 1em; }
18: p + * > li, dd li { margin: 1em 0; }
19: dt, dfn { font-weight: bold; font-style: normal; }
1.300 ihickson 20: i, em { font-style: italic; }
1.82 ihickson 21: dt dfn { font-style: italic; }
22: pre, code { font-size: inherit; font-family: monospace; font-variant: normal; }
23: pre strong { color: black; font: inherit; font-weight: bold; background: yellow; }
24: pre em { font-weight: bolder; font-style: normal; }
1.89 ihickson 25: @media screen { code { color: orangered; } code :link, code :visited { color: inherit; } }
1.82 ihickson 26: var sub { vertical-align: bottom; font-size: smaller; position: relative; top: 0.1em; }
27: table { border-collapse: collapse; border-style: hidden hidden none hidden; }
1.249 ihickson 28: table thead, table tbody { border-bottom: solid; }
1.82 ihickson 29: table tbody th:first-child { border-left: solid; }
1.180 ihickson 30: table tbody th { text-align: left; }
1.82 ihickson 31: table td, table th { border-left: solid; border-right: solid; border-bottom: solid thin; vertical-align: top; padding: 0.2em; }
32: blockquote { margin: 0 0 0 2em; border: 0; padding: 0; font-style: italic; }
33:
34: .bad, .bad *:not(.XXX) { color: gray; border-color: gray; background: transparent; }
35: .matrix, .matrix td { border: none; text-align: right; }
36: .matrix { margin-left: 2em; }
37: .dice-example { border-collapse: collapse; border-style: hidden solid solid hidden; border-width: thin; margin-left: 3em; }
38: .dice-example caption { width: 30em; font-size: smaller; font-style: italic; padding: 0.75em 0; text-align: left; }
39: .dice-example td, .dice-example th { border: solid thin; width: 1.35em; height: 1.05em; text-align: center; padding: 0; }
40:
41: .toc dfn, h1 dfn, h2 dfn, h3 dfn, h4 dfn, h5 dfn, h6 dfn { font: inherit; }
1.305 ihickson 42: img.extra, p.overview { float: right; }
1.304 ihickson 43: pre.idl { border: solid thin; background: #EEEEEE; color: black; padding: 0.5em 1em; position: relative; }
1.82 ihickson 44: pre.idl :link, pre.idl :visited { color: inherit; background: transparent; }
1.304 ihickson 45: pre.idl::before { content: "IDL"; font: bold small sans-serif; padding: 0.5em; background: white; position: absolute; top: 0; margin: -1px 0 0 -4em; width: 1.5em; border: thin solid; border-radius: 0 0 0 0.5em }
1.82 ihickson 46: pre.css { border: solid thin; background: #FFFFEE; color: black; padding: 0.5em 1em; }
47: pre.css:first-line { color: #AAAA50; }
1.231 ihickson 48: dl.domintro { color: green; margin: 2em 0 2em 2em; padding: 0.5em 1em; border: none; background: #DDFFDD; }
1.82 ihickson 49: hr + dl.domintro, div.impl + dl.domintro { margin-top: 2.5em; margin-bottom: 1.5em; }
50: dl.domintro dt, dl.domintro dt * { color: black; text-decoration: none; }
51: dl.domintro dd { margin: 0.5em 0 1em 2em; padding: 0; }
52: dl.domintro dd p { margin: 0.5em 0; }
1.310 ihickson 53: dl.domintro:before { display: table; margin: -1em -0.5em -0.5em auto; width: auto; content: 'This box is non-normative. Implementation requirements are given below this box.'; color: black; font-style: italic; border: solid 2px; background: white; padding: 0 0.25em; }
1.82 ihickson 54: dl.switch { padding-left: 2em; }
55: dl.switch > dt { text-indent: -1.5em; }
56: dl.switch > dt:before { content: '\21AA'; padding: 0 0.5em 0 0; display: inline-block; width: 1em; text-align: right; line-height: 0.5em; }
1.121 ihickson 57: dl.triple { padding: 0 0 0 1em; }
58: dl.triple dt, dl.triple dd { margin: 0; display: inline }
59: dl.triple dt:after { content: ':'; }
60: dl.triple dd:after { content: '\A'; white-space: pre; }
1.82 ihickson 61: .diff-old { text-decoration: line-through; color: silver; background: transparent; }
62: .diff-chg, .diff-new { text-decoration: underline; color: green; background: transparent; }
63: a .diff-new { border-bottom: 1px blue solid; }
64:
65: h2 { page-break-before: always; }
1.139 ihickson 66: h1, h2, h3, h4, h5, h6 { page-break-after: avoid; }
1.82 ihickson 67: h1 + h2, hr + h2.no-toc { page-break-before: auto; }
68:
1.267 ihickson 69: p > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]),
70: li > span:not([title=""]):not([class="XXX"]):not([class="impl"]):not([class="note"]), { border-bottom: solid #9999CC; }
1.82 ihickson 71:
72: div.head { margin: 0 0 1em; padding: 1em 0 0 0; }
73: div.head p { margin: 0; }
74: div.head h1 { margin: 0; }
75: div.head .logo { float: right; margin: 0 1em; }
76: div.head .logo img { border: none } /* remove border from top image */
77: div.head dl { margin: 1em 0; }
1.212 ihickson 78: div.head p.copyright, div.head p.alt { font-size: x-small; font-style: oblique; margin: 0; }
1.82 ihickson 79:
80: body > .toc > li { margin-top: 1em; margin-bottom: 1em; }
81: body > .toc.brief > li { margin-top: 0.35em; margin-bottom: 0.35em; }
82: body > .toc > li > * { margin-bottom: 0.5em; }
83: body > .toc > li > * > li > * { margin-bottom: 0.25em; }
84: .toc, .toc li { list-style: none; }
85:
86: .brief { margin-top: 1em; margin-bottom: 1em; line-height: 1.1; }
87: .brief li { margin: 0; padding: 0; }
88: .brief li p { margin: 0; padding: 0; }
89:
1.137 ihickson 90: .category-list { margin-top: -0.75em; margin-bottom: 1em; line-height: 1.5; }
91: .category-list::before { content: '\21D2\A0'; font-size: 1.2em; font-weight: 900; }
92: .category-list li { display: inline; }
93: .category-list li:not(:last-child)::after { content: ', '; }
94: .category-list li > span, .category-list li > a { text-transform: lowercase; }
95: .category-list li * { text-transform: none; } /* don't affect <code> nested in <a> */
96:
1.82 ihickson 97: .XXX { color: #E50000; background: white; border: solid red; padding: 0.5em; margin: 1em 0; }
98: .XXX > :first-child { margin-top: 0; }
99: p .XXX { line-height: 3em; }
1.158 ihickson 100: .annotation { border: solid thin black; background: #0C479D; color: white; position: relative; margin: 8px 0 20px 0; }
101: .annotation:before { position: absolute; left: 0; top: 0; width: 100%; height: 100%; margin: 6px -6px -6px 6px; background: #333333; z-index: -1; content: ''; }
102: .annotation :link, .annotation :visited { color: inherit; }
103: .annotation :link:hover, .annotation :visited:hover { background: transparent; }
104: .annotation span { border: none ! important; }
1.82 ihickson 105: .note { color: green; background: transparent; font-family: sans-serif; }
106: .warning { color: red; background: transparent; }
107: .note, .warning { font-weight: bolder; font-style: italic; }
1.300 ihickson 108: .note em, .warning em, .note i, .warning i { font-style: normal; }
1.82 ihickson 109: p.note, div.note { padding: 0.5em 2em; }
110: span.note { padding: 0 2em; }
111: .note p:first-child, .warning p:first-child { margin-top: 0; }
112: .note p:last-child, .warning p:last-child { margin-bottom: 0; }
113: .warning:before { font-style: normal; }
114: p.note:before { content: 'Note: '; }
115: p.warning:before { content: '\26A0 Warning! '; }
116:
117: .bookkeeping:before { display: block; content: 'Bookkeeping details'; font-weight: bolder; font-style: italic; }
118: .bookkeeping { font-size: 0.8em; margin: 2em 0; }
119: .bookkeeping p { margin: 0.5em 2em; display: list-item; list-style: square; }
1.262 ihickson 120: .bookkeeping dt { margin: 0.5em 2em 0; }
121: .bookkeeping dd { margin: 0 3em 0.5em; }
1.82 ihickson 122:
123: h4 { position: relative; z-index: 3; }
124: h4 + .element, h4 + div + .element { margin-top: -2.5em; padding-top: 2em; }
125: .element {
1.88 ihickson 126: background: #EEEEFF;
1.82 ihickson 127: color: black;
128: margin: 0 0 1em 0.15em;
129: padding: 0 1em 0.25em 0.75em;
1.88 ihickson 130: border-left: solid #9999FF 0.25em;
1.82 ihickson 131: position: relative;
132: z-index: 1;
133: }
134: .element:before {
135: position: absolute;
136: z-index: 2;
137: top: 0;
138: left: -1.15em;
139: height: 2em;
140: width: 0.9em;
1.88 ihickson 141: background: #EEEEFF;
1.82 ihickson 142: content: ' ';
143: border-style: none none solid solid;
1.88 ihickson 144: border-color: #9999FF;
1.82 ihickson 145: border-width: 0.25em;
146: }
147:
1.156 ihickson 148: .example { display: block; color: #222222; background: #FCFCFC; border-left: double; margin-left: 2em; padding-left: 1em; }
149: td > .example:only-child { margin: 0 0 0 0.1em; }
1.82 ihickson 150:
1.131 ihickson 151: ul.domTree, ul.domTree ul { padding: 0 0 0 1em; margin: 0; }
152: ul.domTree li { padding: 0; margin: 0; list-style: none; position: relative; }
153: ul.domTree li li { list-style: none; }
154: ul.domTree li:first-child::before { position: absolute; top: 0; height: 0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
155: ul.domTree li:not(:last-child)::after { position: absolute; top: 0; bottom: -0.6em; left: -0.75em; width: 0.5em; border-style: none none solid solid; content: ''; border-width: 0.1em; }
156: ul.domTree span { font-style: italic; font-family: serif; }
157: ul.domTree .t1 code { color: purple; font-weight: bold; }
158: ul.domTree .t2 { font-style: normal; font-family: monospace; }
159: ul.domTree .t2 .name { color: black; font-weight: bold; }
160: ul.domTree .t2 .value { color: blue; font-weight: normal; }
161: ul.domTree .t3 code, .domTree .t4 code, .domTree .t5 code { color: gray; }
162: ul.domTree .t7 code, .domTree .t8 code { color: green; }
163: ul.domTree .t10 code { color: teal; }
164:
1.225 ihickson 165: body.dfnEnabled dfn { cursor: pointer; }
166: .dfnPanel {
167: display: inline;
168: position: absolute;
169: z-index: 10;
170: height: auto;
171: width: auto;
172: padding: 0.5em 0.75em;
173: font: small sans-serif, Droid Sans Fallback;
174: background: #DDDDDD;
175: color: black;
176: border: outset 0.2em;
177: }
178: .dfnPanel * { margin: 0; padding: 0; font: inherit; text-indent: 0; }
179: .dfnPanel :link, .dfnPanel :visited { color: black; }
180: .dfnPanel p { font-weight: bolder; }
181: .dfnPanel * + p { margin-top: 0.25em; }
182: .dfnPanel li { list-style-position: inside; }
183:
1.207 ihickson 184: #configUI { position: absolute; z-index: 20; top: 10em; right: 1em; width: 11em; font-size: small; }
185: #configUI p { margin: 0.5em 0; padding: 0.3em; background: #EEEEEE; color: black; border: inset thin; }
186: #configUI p label { display: block; }
187: #configUI #updateUI, #configUI .loginUI { text-align: center; }
188: #configUI input[type=button] { display: block; margin: auto; }
1.260 ihickson 189:
1.268 ihickson 190: fieldset { margin: 1em; padding: 0.5em 1em; }
191: fieldset > legend + * { margin-top: 0; }
1.266 ihickson 192: fieldset > :last-child { margin-bottom: 0; }
1.268 ihickson 193: fieldset p { margin: 0.5em 0; }
1.266 ihickson 194:
1.329 ihickson 195: </style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><meta content="noindex" name="robots"><script type="text/javascript">
1.271 ihickson 196: function getCookie(name) {
197: var params = location.search.substr(1).split("&");
198: for (var index = 0; index < params.length; index++) {
199: if (params[index] == name)
200: return "1";
201: var data = params[index].split("=");
202: if (data[0] == name)
203: return unescape(data[1]);
204: }
205: var cookies = document.cookie.split("; ");
206: for (var index = 0; index < cookies.length; index++) {
207: var data = cookies[index].split("=");
208: if (data[0] == name)
209: return unescape(data[1]);
210: }
211: return null;
212: }
1.327 ihickson 213: </script><body>
214: <div class="head" id="head">
1.115 ihickson 215: <p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
1.271 ihickson 216:
1.54 ihickson 217: <h1>Web Workers</h1>
1.281 ihickson 218:
1.332 ihickson 219: <h2 class="no-num no-toc" id="editor-s-draft-26-june-2012">Editor's Draft 26 June 2012</h2>
1.218 ihickson 220: <dl><dt>Latest Published Version:</dt>
1.115 ihickson 221: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.109 ihickson 222: <dt>Latest Editor's Draft:</dt>
1.260 ihickson 223: <dd><a class="latest-link" href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.284 ihickson 224:
1.318 ihickson 225:
1.2 ihickson 226: <dt>Previous Versions:</dt>
1.279 ihickson 227: <dd><a href="http://www.w3.org/TR/2011/WD-workers-20110310/">http://www.w3.org/TR/2011/WD-workers-20110310/</a></dd>
228: <dd><a href="http://www.w3.org/TR/2011/WD-workers-20110208/">http://www.w3.org/TR/2011/WD-workers-20110208/</a></dd>
1.198 ihickson 229: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20091029/">http://www.w3.org/TR/2009/WD-workers-20091029/</a></dd>
1.279 ihickson 230: <dd><a href="http://www.w3.org/TR/2009/WD-workers-20090423/">http://www.w3.org/TR/2009/WD-workers-20090423/</a></dd>
1.117 ihickson 231: <!-- :ZZZ -->
1.271 ihickson 232: <dt>Editor:</dt>
1.115 ihickson 233: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.</dd>
1.155 ihickson 234: </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
1.328 ihickson 235: © 2012 <a href="http://www.w3.org/"><abbr title="World Wide
1.155 ihickson 236: Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
1.297 ihickson 237: Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr title="European Research
1.115 ihickson 238: Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
239: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
240: <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
241: and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
1.81 ihickson 242: use</a> rules apply.</p>
1.201 ihickson 243:
1.254 ihickson 244:
1.252 ihickson 245: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
1.255 ihickson 246: <p class="alt">The bulk of the text of this specification is also
1.254 ihickson 247: available in the WHATWG <a href="http://www.whatwg.org/specs/web-apps/current-work/complete.html#workers">Web Applications 1.0</a> specification, under a license that permits
248: reuse of the specification text.</p>
1.252 ihickson 249: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
250:
1.254 ihickson 251:
1.327 ihickson 252: </div>
253:
254: <hr class="top"><h2 class="no-num no-toc" id="abstract">Abstract</h2>
255:
256: <p>This specification defines an API that allows Web application
1.81 ihickson 257: authors to spawn background workers running scripts in parallel to
258: their main page. This allows for thread-like operation with
1.327 ihickson 259: message-passing as the coordination mechanism.</p>
260:
261: <h2 class="no-num no-toc" id="status-of-this-document">Status of This document</h2>
262:
263:
264:
265:
266: <p><em>This section describes the status of this document at the
1.81 ihickson 267: time of its publication. Other documents may supersede this
1.297 ihickson 268: document. A list of current W3C publications and the
269:
270: most recently formally published <!-- DO NOT CHANGE THIS BACK TO THE STANDARD BOILERPLATE, AS IT IS INACCURATE -->
271:
272: revision of this technical report can be found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
1.327 ihickson 273: http://www.w3.org/TR/.</em></p>
274:
275:
276:
277:
278: <p>If you wish to make comments regarding this document in a manner
1.271 ihickson 279: that is tracked by the W3C, please submit them via using <a href="http://www.w3.org/Bugs/Public/enter_bug.cgi?product=HTML%20WG">our
280: public bug database</a>. If you do not have an account then you can
1.327 ihickson 281: enter feedback using this form:</p>
282:
283: <form action="http://www.whatwg.org/specs/web-apps/current-work/file-spam.cgi" method="post">
1.271 ihickson 284: <fieldset><legend>Feedback Comments</legend>
285: <input name="id" type="hidden" value="top"><input name="component" type="hidden" value="Web Workers (editor: Ian Hickson)"><input name="response" type="hidden" value="html"><p><label for="feedbackBox">Please enter your feedback, carefully
286: indicating the title of the section for which you are submitting
287: feedback, quoting the text that's wrong today if appropriate. If
288: you're suggesting a new feature, it's really important to say
289: <em>what</em> the problem you're trying to solve is. That's more
290: important than the solution, in fact.</label></p>
291: <p><textarea cols="79" id="feedbackBox" name="text" rows="10"></textarea></p>
292: <p class="note">Please don't use section numbers as these tend to
293: change rapidly and make your feedback harder to understand.</p>
294: <script type="text/javascript">
1.287 ihickson 295: function checkFeedbackForm(form) {
296: if (form.elements.text.value.match(/^ *</)) {
297: alert('Please don\'t start your feedback with an angle bracket, instead explain what topic your feedback is about first.');
298: return true;
299: } else if (form.elements.text.value.match(/ [^ ]+ [^ ]+ [^ ]+ [^ ]+ /)) {
300: if (form.elements.text.value.match(/^Please enter your feedback, carefully/)) {
301: alert('Please enter your feedback, explaining what is wrong, and without repeating the instructions. Thanks!');
302: return true;
303: } else if (form.elements.text.value.match(/ [^ ]+ [^ ]+ [^ ]+ [^ ]+ /)) {
304: form.action = "http://www.whatwg.org/specs/web-apps/current-work/file-bug.cgi";
305: return true;
306: } else {
307: alert('Please include significantly more detail about exactly what problem you are trying to solve.');
308: return false;
309: }
310: }
311: }
1.271 ihickson 312: </script><p>
1.277 ihickson 313: <input onclick="return checkFeedbackForm(form)" type="submit" value="Submit feedback"><small>(Note: Your IP address and user agent will be publicly recorded for spam prevention purposes.)</small>
1.271 ihickson 314: </p>
1.327 ihickson 315: </fieldset></form>
316:
317:
318: <p>You can also e-mail feedback to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a> (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>,
1.271 ihickson 319: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>),
1.115 ihickson 320: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
321: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.327 ihickson 322: All feedback is welcome.</p>
323:
324:
325: <p>Implementors should be aware that this specification is not
1.81 ihickson 326: stable. <strong>Implementors who are not taking part in the
327: discussions are likely to find the specification changing out from
328: under them in incompatible ways.</strong> Vendors interested in
329: implementing this specification before it eventually reaches the
330: Candidate Recommendation stage should join the aforementioned
1.327 ihickson 331: mailing lists and take part in the discussions.</p>
332:
333: <div id="multipage-common">
334: </div>
335:
336: <p>The latest
1.271 ihickson 337: stable version of the editor's draft of this specification is always
338: available on <a href="http://dev.w3.org/html5/workers/">the W3C CVS server</a>
339: and in the <a href="http://svn.whatwg.org/webapps/">WHATWG
340: Subversion repository</a>. The <a href="http://www.whatwg.org/specs/web-apps/current-work/complete.html">latest
341: editor's working copy</a> (which may contain unfinished text in the
342: process of being prepared) contains the latest draft text of this
343: specification (amongst others). For more details, please see the <a href="http://wiki.whatwg.org/wiki/FAQ#What_are_the_various_versions_of_the_spec.3F">WHATWG
1.327 ihickson 344: FAQ</a>.</p>
345:
346: <p>Notifications of changes to this specification are sent along
1.271 ihickson 347: with notifications of changes to related specifications using the
1.327 ihickson 348: following mechanisms:</p>
349: <dl><dt>E-mail notifications of changes</dt>
1.271 ihickson 350: <dd>Commit-Watchers mailing list (complete source diffs): <a href="http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org">http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></dd>
351: <dt>Browsable version-control record of all changes:</dt>
352: <dd>CVSWeb interface with side-by-side diffs: <a href="http://dev.w3.org/cvsweb/html5/">http://dev.w3.org/cvsweb/html5/</a></dd>
353: <dd>Annotated summary with unified diffs: <a href="http://html5.org/tools/web-apps-tracker">http://html5.org/tools/web-apps-tracker</a></dd>
354: <dd>Raw Subversion interface: <code>svn checkout http://svn.whatwg.org/webapps/</code></dd>
355: </dl><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Applications
1.81 ihickson 356: Working Group</a> is the W3C working group responsible for this
357: specification's progress along the W3C Recommendation track.
1.332 ihickson 358: This specification is the 26 June 2012 Editor's Draft.
1.327 ihickson 359: </p>
360:
361:
362:
363: <p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5
1.115 ihickson 364: February 2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/42538/status" rel="disclosure">public list of
1.81 ihickson 365: any patent disclosures</a> made in connection with the deliverables
366: of the group; that page also includes instructions for disclosing a
367: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 368: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
369: Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
1.327 ihickson 370: 6 of the W3C Patent Policy</a>.</p>
371:
372:
373: <h2 class="no-num no-toc" id="contents">Table of Contents</h2>
374:
1.318 ihickson 375:
1.115 ihickson 376: <ol class="toc">
377: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 378: <ol>
1.115 ihickson 379: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
1.303 ihickson 380: <li><a href="#examples"><span class="secno">1.2 </span>Examples</a>
1.81 ihickson 381: <ol>
1.115 ihickson 382: <li><a href="#a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</a></li>
1.323 ihickson 383: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.2 </span>Worker used for background I/O</a></li>
384: <li><a href="#shared-workers-introduction"><span class="secno">1.2.3 </span>Shared workers introduction</a></li>
385: <li><a href="#shared-state-using-a-shared-worker"><span class="secno">1.2.4 </span>Shared state using a shared worker</a></li>
386: <li><a href="#delegation"><span class="secno">1.2.5 </span>Delegation</a></ol></li>
1.303 ihickson 387: <li><a href="#tutorials"><span class="secno">1.3 </span>Tutorials</a>
388: <ol>
389: <li><a href="#creating-a-dedicated-worker"><span class="secno">1.3.1 </span>Creating a dedicated worker</a></li>
390: <li><a href="#communicating-with-a-dedicated-worker"><span class="secno">1.3.2 </span>Communicating with a dedicated worker</a></li>
391: <li><a href="#shared-workers"><span class="secno">1.3.3 </span>Shared workers</a></ol></ol></li>
1.148 ihickson 392: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 393: <ol>
1.148 ihickson 394: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
395: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
396: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
397: <ol>
1.301 ihickson 398: <li><a href="#dependencies-0"><span class="secno">4.1 </span>Dependencies</a></li>
399: <li><a href="#the-global-scope"><span class="secno">4.2 </span>The global scope</a>
1.81 ihickson 400: <ol>
1.316 ihickson 401: <li><a href="#the-workerglobalscope-common-interface"><span class="secno">4.2.1 </span>The <code>WorkerGlobalScope</code> common interface</a></li>
1.301 ihickson 402: <li><a href="#dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.2.2 </span>Dedicated workers and the <code>DedicatedWorkerGlobalScope</code> interface</a></li>
403: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.2.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> interface</a></ol></li>
404: <li><a href="#origins-of-workers"><span class="secno">4.3 </span>Origins of workers</a></li>
405: <li><a href="#the-event-loop"><span class="secno">4.4 </span>The event loop</a></li>
406: <li><a href="#the-worker-s-lifetime"><span class="secno">4.5 </span>The worker's lifetime</a></li>
407: <li><a href="#processing-model"><span class="secno">4.6 </span>Processing model</a></li>
408: <li><a href="#runtime-script-errors"><span class="secno">4.7 </span>Runtime script errors</a></li>
409: <li><a href="#creating-workers"><span class="secno">4.8 </span>Creating workers</a>
1.81 ihickson 410: <ol>
1.301 ihickson 411: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.8.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
412: <li><a href="#dedicated-workers-and-the-worker-interface"><span class="secno">4.8.2 </span>Dedicated workers and the <code>Worker</code> interface</a></li>
413: <li><a href="#shared-workers-and-the-sharedworker-interface"><span class="secno">4.8.3 </span>Shared workers and the <code>SharedWorker</code> interface</a></ol></ol></li>
1.148 ihickson 414: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 415: <ol>
1.148 ihickson 416: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
1.210 ihickson 417: <li><a href="#the-workernavigator-object"><span class="secno">5.2 </span>The <code>WorkerNavigator</code> object</a></li>
1.272 ihickson 418: <li><a href="#interface-objects-and-constructors"><span class="secno">5.3 </span>Interface objects and constructors</a></li>
419: <li><a href="#worker-locations"><span class="secno">5.4 </span>Worker locations</a></ol></li>
1.115 ihickson 420: <li><a class="no-num" href="#references">References</a></li>
421: <li><a class="no-num" href="#acknowledgements">Acknowledgements</a></ol>
1.327 ihickson 422:
423: <hr><h2 id="introduction"><span class="secno">1 </span>Introduction</h2>
424:
425: <h3 id="scope"><span class="secno">1.1 </span>Scope</h3>
426:
427: <p><i>This section is non-normative.</i></p>
428:
429: <p>This specification defines an API for running scripts in the
430: background independently of any user interface scripts.</p>
431:
432: <p>This allows for long-running scripts that are not interrupted by
1.81 ihickson 433: scripts that respond to clicks or other user interactions, and
434: allows long tasks to be executed without yielding to keep the page
1.327 ihickson 435: responsive.</p>
436:
437: <p>Workers (as these background scripts are called herein) are
1.81 ihickson 438: relatively heavy-weight, and are not intended to be used in large
439: numbers. For example, it would be inappropriate to launch one worker
440: for each pixel of a four megapixel image. The examples below show
1.327 ihickson 441: some appropriate uses of workers.</p>
442:
443: <p>Generally, workers are expected to be long-lived, have a high
444: start-up performance cost, and a high per-instance memory cost.</p>
445:
446:
447: <h3 id="examples"><span class="secno">1.2 </span>Examples</h3>
448:
449: <p><i>This section is non-normative.</i></p>
450:
451: <p>There are a variety of uses that workers can be put to. The
452: following subsections show various examples of this use.</p>
453:
454: <h4 id="a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</h4>
455:
456: <p><i>This section is non-normative.</i></p>
457:
458: <p>The simplest use of workers is for performing a computationally
459: expensive task without interrupting the user interface.</p>
460:
461: <p>In this example, the main document spawns a worker to
1.155 ihickson 462: (naïvely) compute prime numbers, and progressively displays the
1.327 ihickson 463: most recently found prime number.</p>
464:
465: <p>The main page is as follows:</p>
466:
467: <pre><!DOCTYPE HTML>
1.81 ihickson 468: <html>
469: <head>
470: <title>Worker example: One-core computation</title>
471: </head>
472: <body>
473: <p>The highest prime number discovered so far is: <output id="result"></output></p>
474: <script>
1.50 ihickson 475: var worker = new Worker('worker.js');
476: worker.onmessage = function (event) {
1.54 ihickson 477: document.getElementById('result').textContent = event.data;
1.29 ihickson 478: };
1.81 ihickson 479: </script>
480: </body>
1.327 ihickson 481: </html></pre>
482:
483: <p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call
1.115 ihickson 484: creates a worker and returns a <code><a href="#worker">Worker</a></code> object
1.81 ihickson 485: representing that worker, which is used to communicate with the
1.327 ihickson 486: worker. That object's <code title="handler-Worker-onmessage"><a href="#handler-worker-onmessage">onmessage</a></code> event handler allows the code to receive messages from the worker.</p>
487:
488: <p>The worker itself is as follows:</p>
489:
490: <pre>var n = 1;
1.29 ihickson 491: search: while (true) {
492: n += 1;
493: for (var i = 2; i <= Math.sqrt(n); i += 1)
494: if (n % i == 0)
495: continue search;
496: // found a prime!
1.50 ihickson 497: postMessage(n);
1.327 ihickson 498: }</pre>
499:
500: <p>The bulk of this code is simply an unoptimized search for a prime
1.295 ihickson 501: number. The <code title="dom-DedicatedWorkerGlobalScope-postMessage"><a href="#dom-dedicatedworkerglobalscope-postmessage">postMessage()</a></code>
502: method is used to send a message back to the page when a prime is
1.327 ihickson 503: found.</p>
504:
505: <p><a href="http://www.whatwg.org/demos/workers/primes/page.html">View this example online</a>.</p>
506:
507:
508:
509:
510: <h4 id="worker-used-for-background-i-o"><span class="secno">1.2.2 </span>Worker used for background I/O</h4>
511:
512: <p><i>This section is non-normative.</i></p>
513:
514: <p>In this example, the main document uses two workers, one for
1.81 ihickson 515: fetching stock updates for at regular intervals, and one for
1.327 ihickson 516: fetching performing search queries that the user requests.</p>
517:
518: <p>The main page is as follows:</p>
519:
520: <pre><!DOCTYPE HTML>
1.81 ihickson 521: <html>
522: <head>
523: <title>Worker example: Stock ticker</title>
524: <script>
1.33 ihickson 525: // TICKER
526: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 527: var ticker = new Worker('ticker.js');
1.33 ihickson 528:
529: // SEARCHER
1.50 ihickson 530: var searcher = new Worker('searcher.js');
1.33 ihickson 531: function search(query) {
1.50 ihickson 532: searcher.postMessage(query);
1.33 ihickson 533: }
534:
535: // SYMBOL SELECTION UI
536: function select(newSymbol) {
537: symbol = newSymbol;
1.50 ihickson 538: ticker.postMessage(symbol);
1.33 ihickson 539: }
1.81 ihickson 540: </script>
541: </head>
1.122 ihickson 542: <body onload="search('')">
1.81 ihickson 543: <p><output id="symbol"></output> <output id="value"></output></p>
544: <script>
1.50 ihickson 545: ticker.onmessage = function (event) {
1.54 ihickson 546: var data = event.data.split(' ');
1.33 ihickson 547: document.getElementById('symbol').textContent = data[0];
548: document.getElementById('value').textContent = data[1];
549: };
1.50 ihickson 550: ticker.postMessage(symbol);
1.81 ihickson 551: </script>
1.122 ihickson 552: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 553: <ul id="results"></ul>
554: <script>
1.50 ihickson 555: searcher.onmessage = function (event) {
1.54 ihickson 556: var data = event.data.split(' ');
1.33 ihickson 557: var results = document.getElementById('results');
558: while (results.hasChildNodes()) // clear previous results
559: results.removeChild(results.firstChild);
560: for (var i = 0; i < data.length; i += 1) {
561: // add a list item with a button for each result
562: var li = document.createElement('li');
563: var button = document.createElement('button');
564: button.value = data[i];
565: button.type = 'button';
566: button.onclick = function () { select(this.value); };
567: button.textContent = data[i];
568: li.appendChild(button);
569: results.appendChild(li);
570: }
571: };
1.81 ihickson 572: </script>
573: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
574: </body>
1.327 ihickson 575: </html></pre>
576:
577: <p>The two workers use a common library for performing the actual
578: network calls. This library is as follows:</p>
579:
580: <pre>function get(url) {
1.50 ihickson 581: try {
582: var xhr = new XMLHttpRequest();
583: xhr.open('GET', url, false);
584: xhr.send();
585: return xhr.responseText;
586: } catch (e) {
587: return ''; // turn all errors into empty results
588: }
1.327 ihickson 589: }</pre>
590:
591: <p>The stock updater worker is as follows:</p>
592:
593: <pre>importScripts('io.js');
1.33 ihickson 594: var timer;
595: var symbol;
596: function update() {
1.50 ihickson 597: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 598: timer = setTimeout(update, 10000);
599: }
1.50 ihickson 600: onmessage = function (event) {
1.33 ihickson 601: if (timer)
602: clearTimeout(timer);
1.54 ihickson 603: symbol = event.data;
1.33 ihickson 604: update();
1.327 ihickson 605: };</pre>
606:
607: <p>The search query worker is as follows:</p>
608:
609: <pre>importScripts('io.js');
1.50 ihickson 610: onmessage = function (event) {
1.54 ihickson 611: postMessage(get('search.cgi?' + event.data));
1.327 ihickson 612: };</pre>
613:
614: <p><a href="http://www.whatwg.org/demos/workers/stocks/page.html">View this example online</a>.</p>
615:
616:
617: <h4 id="shared-workers-introduction"><span class="secno">1.2.3 </span>Shared workers introduction</h4>
618:
619: <p><i>This section is non-normative.</i></p>
620:
621: <p>This section introduces shared workers using a Hello World
1.238 ihickson 622: example. Shared workers use slightly different APIs, since each
1.327 ihickson 623: worker can have multiple connections.</p>
624:
625: <p>This first example shows how you connect to a worker and how a
1.238 ihickson 626: worker can send a message back to the page when it connects to
1.327 ihickson 627: it. Received messages are displayed in a log.</p>
628:
629: <p>Here is the HTML page:</p>
630:
631: <pre><!DOCTYPE HTML>
1.239 ihickson 632: <title>Shared workers: demo 1</title>
633: <pre id="log">Log:</pre>
634: <script>
635: var worker = new SharedWorker('test.js');
636: var log = document.getElementById('log');
637: worker.port.onmessage = function(e) { // note: not worker.onmessage!
638: log.textContent += '\n' + e.data;
639: }
640: </script>
1.327 ihickson 641: </pre>
642:
643: <p>Here is the JavaScript worker:</p>
644:
645: <pre>onconnect = function(e) {
1.239 ihickson 646: var port = e.ports[0];
647: port.postMessage('Hello World!');
648: }
1.327 ihickson 649: </pre>
650:
651: <p><a href="http://www.whatwg.org/demos/workers/shared/001/test.html">View this example online</a>.</p>
652:
653: <hr><p>This second example extends the first one by changing two things:
1.238 ihickson 654: first, messages are received using <code title="">addEventListener()</code> instead of an <span title="event
655: handler IDL attributes">event handler IDL attribute</span>, and
656: second, a message is sent <em>to</em> the worker, causing the worker
657: to send another message in return. Received messages are again
1.327 ihickson 658: displayed in a log.</p>
659:
660: <p>Here is the HTML page:</p>
661:
662: <pre><!DOCTYPE HTML>
1.240 ihickson 663: <title>Shared workers: demo 2</title>
1.239 ihickson 664: <pre id="log">Log:</pre>
665: <script>
666: var worker = new SharedWorker('test.js');
667: var log = document.getElementById('log');
1.240 ihickson 668: worker.port.addEventListener('message', function(e) {
1.239 ihickson 669: log.textContent += '\n' + e.data;
1.240 ihickson 670: }, false);
671: worker.port.start(); // note: need this when using addEventListener
672: worker.port.postMessage('ping');
1.239 ihickson 673: </script>
1.327 ihickson 674: </pre>
675:
676: <p>Here is the JavaScript worker:</p>
677:
678: <pre>onconnect = function(e) {
1.239 ihickson 679: var port = e.ports[0];
680: port.postMessage('Hello World!');
1.240 ihickson 681: port.onmessage = function(e) {
682: port.postMessage('pong'); // not e.ports[0].postMessage!
683: // e.target.postMessage('pong'); would work also
684: }
1.239 ihickson 685: }
1.327 ihickson 686: </pre>
687:
688: <p><a href="http://www.whatwg.org/demos/workers/shared/002/test.html">View this example online</a>.</p>
689:
690: <hr><p>Finally, the example is extended to show how two pages can
1.238 ihickson 691: connect to the same worker; in this case, the second page is merely
692: in an <code>iframe</code> on the first page, but the same principle
693: would apply to an entirely separate page in a separate
1.327 ihickson 694: <span>top-level browsing context</span>.</p>
695:
696: <p>Here is the outer HTML page:</p>
697:
698: <pre><!DOCTYPE HTML>
1.239 ihickson 699: <title>Shared workers: demo 3</title>
700: <pre id="log">Log:</pre>
701: <script>
702: var worker = new SharedWorker('test.js');
703: var log = document.getElementById('log');
704: worker.port.addEventListener('message', function(e) {
705: log.textContent += '\n' + e.data;
706: }, false);
707: worker.port.start();
708: worker.port.postMessage('ping');
709: </script>
710: <iframe src="inner.html"></iframe>
1.327 ihickson 711: </pre>
712:
713: <p>Here is the inner HTML page:</p>
714:
715: <pre><!DOCTYPE HTML>
1.239 ihickson 716: <title>Shared workers: demo 3 inner frame</title>
717: <pre id=log>Inner log:</pre>
718: <script>
719: var worker = new SharedWorker('test.js');
720: var log = document.getElementById('log');
721: worker.port.onmessage = function(e) {
722: log.textContent += '\n' + e.data;
723: }
724: </script>
1.327 ihickson 725: </pre>
726:
727: <p>Here is the JavaScript worker:</p>
728:
729: <pre>var count = 0;
1.239 ihickson 730: onconnect = function(e) {
731: count += 1;
732: var port = e.ports[0];
733: port.postMessage('Hello World! You are connection #' + count);
734: port.onmessage = function(e) {
735: port.postMessage('pong');
736: }
737: }
1.327 ihickson 738: </pre>
739:
740: <p><a href="http://www.whatwg.org/demos/workers/shared/003/test.html">View this example online</a>.</p>
741:
742:
743: <h4 id="shared-state-using-a-shared-worker"><span class="secno">1.2.4 </span>Shared state using a shared worker</h4>
744:
745: <p><i>This section is non-normative.</i></p>
746:
747: <p>In this example, multiple windows (viewers) can be opened that
1.81 ihickson 748: are all viewing the same map. All the windows share the same map
749: information, with a single worker coordinating all the viewers. Each
750: viewer can move around independently, but if they set any data on
1.327 ihickson 751: the map, all the viewers are updated.</p>
752:
753: <p>The main page isn't interesting, it merely provides a way to open
754: the viewers:</p>
755:
756: <pre><!DOCTYPE HTML>
1.81 ihickson 757: <html>
758: <head>
759: <title>Workers example: Multiviewer</title>
760: <script>
1.36 ihickson 761: function openViewer() {
762: window.open('viewer.html');
763: }
1.81 ihickson 764: </script>
765: </head>
766: <body>
767: <p><button type=button onclick="openViewer()">Open a new
768: viewer</button></p>
769: <p>Each viewer opens in a new window. You can have as many viewers
770: as you like, they all view the same data.</p>
771: </body>
1.327 ihickson 772: </html></pre>
773:
774: <p>The viewer is more involved:</p>
775:
776: <pre><!DOCTYPE HTML>
1.81 ihickson 777: <html>
778: <head>
779: <title>Workers example: Multiviewer viewer</title>
780: <script>
1.50 ihickson 781: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 782:
783: // CONFIGURATION
784: function configure(event) {
1.54 ihickson 785: if (event.data.substr(0, 4) != 'cfg ') return;
786: var name = event.data.substr(4).split(' ', 1);
1.36 ihickson 787: // update display to mention our name is name
788: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
789: // no longer need this listener
1.43 ihickson 790: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 791: }
1.53 ihickson 792: worker.port.addEventListener('message', configure, false);
1.36 ihickson 793:
794: // MAP
795: function paintMap(event) {
1.54 ihickson 796: if (event.data.substr(0, 4) != 'map ') return;
797: var data = event.data.substr(4).split(',');
1.36 ihickson 798: // display tiles data[0] .. data[8]
799: var canvas = document.getElementById('map');
800: var context = canvas.getContext('2d');
801: for (var y = 0; y < 3; y += 1) {
802: for (var x = 0; x < 3; x += 1) {
803: var tile = data[y * 3 + x];
804: if (tile == '0')
805: context.fillStyle = 'green';
806: else
807: context.fillStyle = 'maroon';
808: fillRect(x * 50, y * 50, 50, 50);
809: }
810: }
811: }
1.53 ihickson 812: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 813:
814: // PUBLIC CHAT
815: function updatePublicChat(event) {
1.54 ihickson 816: if (event.data.substr(0, 4) != 'txt ') return;
817: var name = event.data.substr(4).split(' ', 1);
818: var message = event.data.substr(4 + length(name) + 1);
1.81 ihickson 819: // display "<name> message" in public chat
1.36 ihickson 820: var dialog = document.getElementById('public');
821: var dt = document.createElement('dt');
822: dt.textContent = name;
823: dialog.appendChild(dt);
824: var dd = document.createElement('dd');
825: dd.textContent = message;
826: dialog.appendChild(dd);
827: }
1.53 ihickson 828: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 829:
830: // PRIVATE CHAT
831: function startPrivateChat(event) {
1.54 ihickson 832: if (event.data.substr(0, 4) != 'msg ') return;
833: var name = event.data.substr(4).split(' ', 1);
1.84 ihickson 834: var port = event.ports[0];
1.36 ihickson 835: // display a private chat UI
836: var ul = document.getElementById('private');
837: var li = document.createElement('li');
838: var h3 = document.createElement('h3');
839: h3.textContent = 'Private chat with ' + name;
840: li.appendChild(h3);
841: var dialog = document.createElement('dialog');
842: var addMessage = function(name, message) {
843: var dt = document.createElement('dt');
844: dt.textContent = name;
845: dialog.appendChild(dt);
846: var dd = document.createElement('dd');
847: dd.textContent = message;
848: dialog.appendChild(dd);
849: };
850: port.onmessage = function (event) {
1.54 ihickson 851: addMessage(name, event.data);
1.36 ihickson 852: };
853: li.appendChild(dialog);
854: var form = document.createElement('form');
855: var p = document.createElement('p');
856: var input = document.createElement('input');
857: input.size = 50;
858: p.appendChild(input);
859: p.appendChild(document.createTextNode(' '));
860: var button = document.createElement('button');
861: button.textContent = 'Post';
862: p.appendChild(button);
863: form.onsubmit = function () {
864: port.postMessage(input.value);
865: addMessage('me', input.value);
866: input.value = '';
867: return false;
868: };
869: form.appendChild(p);
870: li.appendChild(form);
871: }
1.53 ihickson 872: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 873:
874: worker.port.start();
1.81 ihickson 875: </script>
876: </head>
877: <body>
878: <h1>Viewer</h1>
879: <h2>Map</h2>
880: <p><canvas id="map" height=150 width=150></canvas></p>
881: <p>
882: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
883: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
884: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
885: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
886: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
887: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
888: </p>
889: <h2>Public Chat</h2>
890: <dialog id="public"></dialog>
891: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
892: <p>
893: <input type="text" name="message" size="50">
894: <button>Post</button>
895: </p>
896: </form>
897: <h2>Private Chat</h2>
898: <ul id="private"></ul>
899: </body>
900: </html>
1.327 ihickson 901: </pre>
902:
903: <p>There are several key things worth noting about the way the
904: viewer is written.</p>
905:
906: <p><strong>Multiple listeners</strong>. Instead of a single message
1.81 ihickson 907: processing function, the code here attaches multiple event
908: listeners, each one performing a quick check to see if it is
909: relevant for the message. In this example it doesn't make much
910: difference, but if multiple authors wanted to collaborate using a
911: single port to communicate with a worker, it would allow for
912: independent code instead of changes having to all be made to a
1.327 ihickson 913: single event handling function.</p>
914:
915: <p>Registering event listeners in this way also allows you to
1.81 ihickson 916: unregister specific listeners when you are done with them, as is
917: done with the <code title="">configure()</code> method in this
1.327 ihickson 918: example.</p>
919:
920: <p>Finally, the worker:</p>
921:
922: <pre>
1.155 ihickson 923: var nextName = 0;
1.36 ihickson 924: function getNextName() {
925: // this could use more friendly names
926: // but for now just return a number
927: return nextName++;
928: }
929:
930: var map = [
931: [0, 0, 0, 0, 0, 0, 0],
932: [1, 1, 0, 1, 0, 1, 1],
933: [0, 1, 0, 1, 0, 0, 0],
934: [0, 1, 0, 1, 0, 1, 1],
935: [0, 0, 0, 1, 0, 0, 0],
936: [1, 0, 0, 1, 1, 1, 1],
937: [1, 1, 0, 1, 1, 0, 1],
938: ];
939:
940: function wrapX(x) {
941: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 942: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 943: return x;
944: }
945:
946: function wrapY(y) {
947: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 948: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 949: return y;
950: }
951:
1.50 ihickson 952: function sendMapData(callback) {
1.36 ihickson 953: var data = '';
954: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
955: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
956: if (data != '')
957: data += ',';
958: data += map[y][x];
959: }
960: }
1.50 ihickson 961: callback('map ' + data);
1.36 ihickson 962: }
963:
964: var viewers = {};
965: onconnect = function (event) {
1.84 ihickson 966: event.ports[0]._name = getNextName();
967: event.ports[0]._data = { port: event.port, x: 0, y: 0, };
968: viewers[event.ports[0]._name] = event.port._data;
969: event.ports[0].postMessage('cfg ' + name);
970: event.ports[0].onmessage = getMessage;
971: sendMapData(event.ports[0].postMessage);
1.36 ihickson 972: };
973:
974: function getMessage(event) {
1.54 ihickson 975: switch (event.data.substr(0, 4)) {
1.36 ihickson 976: case 'mov ':
1.54 ihickson 977: var direction = event.data.substr(4);
1.36 ihickson 978: var dx = 0;
979: var dy = 0;
980: switch (direction) {
981: case 'up': dy = -1; break;
982: case 'down': dy = 1; break;
983: case 'left': dx = -1; break;
984: case 'right': dx = 1; break;
985: }
986: event.target._data.x = wrapX(event.target._data.x + dx);
987: event.target._data.y = wrapY(event.target._data.y + dy);
1.50 ihickson 988: sendMapData(event.target.postMessage);
1.36 ihickson 989: break;
990: case 'set ':
1.54 ihickson 991: var value = event.data.substr(4);
1.36 ihickson 992: map[event.target._data.y][event.target._data.x] = value;
993: for (var viewer in viewers)
1.50 ihickson 994: sendMapData(viewers[viewer].port.postMessage);
1.36 ihickson 995: break;
996: case 'txt ':
997: var name = event.target._name;
1.54 ihickson 998: var message = event.data.substr(4);
1.36 ihickson 999: for (var viewer in viewers)
1000: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
1001: break;
1002: case 'msg ':
1003: var party1 = event._data;
1.54 ihickson 1004: var party2 = viewers[event.data.substr(4).split(' ', 1)];
1.36 ihickson 1005: if (party2) {
1006: var channel = new MessageChannel();
1.84 ihickson 1007: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
1008: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 1009: }
1010: break;
1011: }
1.327 ihickson 1012: }</pre>
1013:
1014: <p><strong>Connecting to multiple pages</strong>. The script uses
1.115 ihickson 1015: the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code>
1.327 ihickson 1016: event listener to listen for multiple connections.</p>
1017:
1018: <p><strong>Direct channels</strong>. When the worker receives a
1.81 ihickson 1019: "msg" message from one viewer naming another viewer, it sets up a
1020: direct connection between the two, so that the two viewers can
1021: communicate directly without the worker having to proxy all the
1.327 ihickson 1022: messages.</p>
1023:
1024: <p><a href="http://www.whatwg.org/demos/workers/multiviewer/page.html">View this example online</a>.</p>
1025:
1026:
1027: <h4 id="delegation"><span class="secno">1.2.5 </span>Delegation</h4>
1028:
1029: <p><i>This section is non-normative.</i></p>
1030:
1031: <p>With multicore CPUs becoming prevalent, one way to obtain better
1.81 ihickson 1032: performance is to split computationally expensive tasks amongst
1033: multiple workers. In this example, a computationally expensive task
1034: that is to be performed for every number from 1 to 10,000,000 is
1.327 ihickson 1035: farmed out to ten subworkers.</p>
1036:
1037: <p>The main page is as follows, it just reports the result:</p>
1038:
1039: <pre><!DOCTYPE HTML>
1.81 ihickson 1040: <html>
1041: <head>
1.203 ihickson 1042: <title>Worker example: Multicore computation</title>
1.81 ihickson 1043: </head>
1044: <body>
1.203 ihickson 1045: <p>Result: <output id="result"></output></p>
1.81 ihickson 1046: <script>
1.50 ihickson 1047: var worker = new Worker('worker.js');
1048: worker.onmessage = function (event) {
1.54 ihickson 1049: document.getElementById('result').textContent = event.data;
1.40 ihickson 1050: };
1.81 ihickson 1051: </script>
1052: </body>
1.327 ihickson 1053: </html></pre>
1054:
1055: <p>The worker itself is as follows:</p>
1056:
1057: <pre>// settings
1.40 ihickson 1058: var num_workers = 10;
1059: var items_per_worker = 1000000;
1060:
1061: // start the workers
1062: var result = 0;
1063: var pending_workers = num_workers;
1064: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 1065: var worker = new Worker('core.js');
1066: worker.postMessage(i * items_per_worker);
1067: worker.postMessage((i+1) * items_per_worker);
1068: worker.onmessage = storeResult;
1.40 ihickson 1069: }
1070:
1071: // handle the results
1072: function storeResult(event) {
1.54 ihickson 1073: result += 1*event.data;
1.40 ihickson 1074: pending_workers -= 1;
1075: if (pending_workers <= 0)
1.50 ihickson 1076: postMessage(result); // finished!
1.327 ihickson 1077: }</pre>
1078:
1079: <p>It consists of a loop to start the subworkers, and then a handler
1080: that waits for all the subworkers to respond.</p>
1081:
1082: <p>The subworkers are implemented as follows:</p>
1083:
1084: <pre>var start;
1.41 ihickson 1085: onmessage = getStart;
1.40 ihickson 1086: function getStart(event) {
1.54 ihickson 1087: start = 1*event.data;
1.40 ihickson 1088: onmessage = getEnd;
1089: }
1090:
1091: var end;
1092: function getEnd(event) {
1.54 ihickson 1093: end = 1*event.data;
1.40 ihickson 1094: onmessage = null;
1.66 ihickson 1095: work();
1.40 ihickson 1096: }
1097:
1.66 ihickson 1098: function work() {
1.40 ihickson 1099: var result = 0;
1100: for (var i = start; i < end; i += 1) {
1101: // perform some complex calculation here
1102: result += 1;
1103: }
1.50 ihickson 1104: postMessage(result);
1105: close();
1.327 ihickson 1106: }</pre>
1107:
1108: <p>They receive two numbers in two events, perform the computation
1.81 ihickson 1109: for the range of numbers thus specified, and then report the result
1.327 ihickson 1110: back to the parent.</p>
1111:
1112: <p><a href="http://www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.</p>
1113:
1114:
1115:
1116:
1117: <h3 id="tutorials"><span class="secno">1.3 </span>Tutorials</h3>
1118:
1119: <h4 id="creating-a-dedicated-worker"><span class="secno">1.3.1 </span>Creating a dedicated worker</h4>
1120:
1121: <p><i>This section is non-normative.</i></p>
1122:
1123: <p>Creating a worker requires a URL to a JavaScript file. The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor is invoked with the
1.303 ihickson 1124: URL to that file as its only argument; a worker is then created and
1.327 ihickson 1125: returned:</p>
1126:
1127: <pre>var worker = new Worker('helper.js');</pre>
1128:
1129:
1130: <h4 id="communicating-with-a-dedicated-worker"><span class="secno">1.3.2 </span>Communicating with a dedicated worker</h4>
1131:
1132: <p><i>This section is non-normative.</i></p>
1133:
1134: <p>Dedicated workers use <code><a href="#messageport">MessagePort</a></code> objects behind the
1.303 ihickson 1135: scenes, and thus support all the same features, such as sending
1136: structured data, transferring binary data, and transferring other
1.327 ihickson 1137: ports.</p>
1138:
1139: <p>To receive messages from a dedicated worker, use the <code title="handler-worker-onmessage"><a href="#handler-worker-onmessage">onmessage</a></code> <span title="event
1.303 ihickson 1140: handler IDL attributes">event handler IDL attribute</span> on the
1.327 ihickson 1141: <code><a href="#worker">Worker</a></code> object:</p>
1142:
1143: <pre>worker.onmessage = function (event) { ... };</pre>
1144:
1145: <p>You can also use the <code title="dom-EventTarget-addEventListener">addEventListener()</code> method.</p>
1146:
1147: <p class="note">The implicit <code><a href="#messageport">MessagePort</a></code> used by
1.303 ihickson 1148: dedicated workers has its <span>port message queue</span> implicitly
1149: enabled when it is created, so there is no equivanet to the
1150: <code><a href="#messageport">MessagePort</a></code> interface's <code title="dom-MessagePort-start">start()</code> method on the
1.327 ihickson 1151: <code><a href="#worker">Worker</a></code> interface.</p>
1152:
1153: <p>To <em>send</em> data to a worker, use the <code title="dom-Worker-postMessage"><a href="#dom-worker-postmessage">postMessage()</a></code> method.
1.303 ihickson 1154: Structured data can be sent over this communication channel. To send
1155: <code>ArrayBuffer</code> objects efficiently (by transferring them
1156: rather than cloning them), list them in an array in the second
1.327 ihickson 1157: argument.</p>
1158:
1159: <pre>worker.postMessage({
1.303 ihickson 1160: operation: 'find-edges',
1161: input: buffer, // an ArrayBuffer object
1162: threshold: 0.6,
1.327 ihickson 1163: }, [buffer]);</pre>
1164:
1165: <p>To receive a message inside the worker, the <code title="handler-DedicatedWorkerGlobalScope-onmessage"><a href="#handler-dedicatedworkerglobalscope-onmessage">onmessage</a></code>
1.303 ihickson 1166: <span title="event handler IDL attributes">event handler IDL
1.327 ihickson 1167: attribute</span> is used.</p>
1168:
1169: <pre>onmessage = function (event) { ... };</pre>
1170:
1171: <p>You can again also use the <code title="dom-EventTarget-addEventListener">addEventListener()</code>
1172: method.</p>
1173:
1174: <p>In either case, the data is provided in the event object's <code title="dom-MessageEvent-data">data</code> attribute.</p>
1175:
1176: <p>To send messages back, you again use <code title="dom-DedicatedWorkerGlobalScope-postMessage"><a href="#dom-dedicatedworkerglobalscope-postmessage">postMessage()</a></code>.
1177: It supports the structured data in the same manner.</p>
1178:
1179: <pre>postMessage(event.data.input, [event.data.input]); // transfer the buffer back</pre>
1180:
1181:
1182: <h4 id="shared-workers"><span class="secno">1.3.3 </span>Shared workers</h4>
1183:
1184: <p><i>This section is non-normative.</i></p>
1185:
1186: <p>Shared workers are identified in one of two ways: either by the
1.303 ihickson 1187: URL of the script used to create it, or by explicit name. When
1188: created by name, the URL used by the first page to create the worker
1189: with that name is the URL of the script that will be used for that
1190: worker. This allows multiple applications on a domain to all use a
1191: single shared worker to provide a common service, without the
1192: applications having to keep track of a common URL for the script
1.327 ihickson 1193: used to provide the service.</p>
1194:
1195: <p class="note">In either case, shared workers are scoped by
1.303 ihickson 1196: <span>origin</span>. Two different sites using the same names will
1.327 ihickson 1197: not collide.</p>
1198:
1199: <p>Creating shared workers is done using the <code title="dom-SharedWorker"><a href="#dom-sharedworker">SharedWorker()</a></code> constructor. This
1.303 ihickson 1200: constructor takes the URL to the script to use for its first
1201: argument, and the name of the worker, if any, as the second
1.327 ihickson 1202: argument.</p>
1203:
1204: <pre>var worker = new SharedWorker('service.js');</pre>
1205:
1206: <p>Communicating with shared workers is done with explicit
1.303 ihickson 1207: <code><a href="#messageport">MessagePort</a></code> objects. The object returned by the <code title="dom-SharedWorker"><a href="#dom-sharedworker">SharedWorker()</a></code> constructor holds a
1.327 ihickson 1208: reference to the port on its <code title="dom-SharedWorker-port"><a href="#dom-sharedworker-port">port</a></code> attribute.</p>
1209:
1210: <pre>worker.port.onmessage = function (event) { ... };
1.303 ihickson 1211: worker.port.postMessage('some message');
1.327 ihickson 1212: worker.port.postMessage({ foo: 'structured', bar: ['data', 'also', 'possible']});</pre>
1213:
1214: <p>Inside the shared worker, new clients of the worker are announced
1.303 ihickson 1215: using the <code title="event-connect">connect</code> event. The port
1.330 ihickson 1216: for the new client is given by the event object's <code title="dom-messageevent-source">source</code> attribute.</p>
1.327 ihickson 1217:
1218: <pre>onconnect = function (event) {
1.330 ihickson 1219: var newPort = event.source;
1.303 ihickson 1220: // set up a listener
1221: newPort.onmessage = function (event) { ... };
1222: // send a message back to the port
1223: newPort.postMessage('ready!'); // can also send structured data, of course
1.327 ihickson 1224: };</pre>
1225:
1226:
1227:
1228:
1229:
1230:
1231: <h2 id="conformance-requirements"><span class="secno">2 </span>Conformance requirements</h2>
1232:
1233: <p>All diagrams, examples, and notes in this specification are
1.81 ihickson 1234: non-normative, as are all sections explicitly marked non-normative.
1.327 ihickson 1235: Everything else in this specification is normative.</p>
1236:
1237: <p>The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
1.81 ihickson 1238: "OPTIONAL" in the normative parts of this document are to be
1239: interpreted as described in RFC2119. For readability, these words do
1.327 ihickson 1240: not appear in all uppercase letters in this specification. <a href="#refsRFC2119">[RFC2119]</a></p>
1241:
1242: <p>Requirements phrased in the imperative as part of algorithms
1.81 ihickson 1243: (such as "strip any leading space characters" or "return false and
1244: abort these steps") are to be interpreted with the meaning of the
1245: key word ("must", "should", "may", etc) used in introducing the
1.327 ihickson 1246: algorithm.</p>
1247:
1248: <p>Some conformance requirements are phrased as requirements on
1.81 ihickson 1249: attributes, methods or objects. Such requirements are to be
1.327 ihickson 1250: interpreted as requirements on user agents.</p>
1251:
1252: <p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 1253: may be implemented in any manner, so long as the end result is
1254: equivalent. (In particular, the algorithms defined in this
1255: specification are intended to be easy to follow, and not intended to
1.327 ihickson 1256: be performant.)</p>
1257:
1258: <p>The only conformance class defined by this specification is user
1259: agents.</p>
1260:
1261: <p>User agents may impose implementation-specific limits on
1.81 ihickson 1262: otherwise unconstrained inputs, e.g. to prevent denial of service
1263: attacks, to guard against running out of memory, or to work around
1.327 ihickson 1264: platform-specific limitations.</p>
1265:
1266: <p>When support for a feature is disabled (e.g. as an emergency
1.229 ihickson 1267: measure to mitigate a security problem, or to aid in development, or
1268: for performance reasons), user agents must act as if they had no
1269: support for the feature whatsoever, and as if the feature was not
1270: mentioned in this specification. For example, if a particular
1271: feature is accessed via an attribute in a Web IDL interface, the
1272: attribute itself would be omitted from the objects that implement
1273: that interface — leaving the attribute on the object but
1.327 ihickson 1274: making it return null or throw an exception is insufficient.</p>
1275:
1276:
1277: <h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3>
1278:
1279: <p>This specification relies on several other underlying
1280: specifications.</p>
1281:
1282: <dl><dt>HTML</dt>
1.49 ihickson 1283:
1.81 ihickson 1284: <dd>
1.49 ihickson 1285:
1.226 ihickson 1286: <p>Many fundamental concepts from HTML are used by this
1287: specification. <a href="#refsHTML">[HTML]</a></p>
1.49 ihickson 1288:
1.81 ihickson 1289: </dd>
1.1 ihickson 1290:
1.81 ihickson 1291: <dt>WebIDL</dt>
1.1 ihickson 1292:
1293: <dd>
1294:
1.81 ihickson 1295: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 1296: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 1297:
1.81 ihickson 1298: </dd>
1.1 ihickson 1299:
1.327 ihickson 1300: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2>
1301:
1302: <p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 1303: <code title="">Foo</code> is actually an interface, is sometimes
1304: used instead of the more accurate "an object implementing the
1.327 ihickson 1305: interface <code title="">Foo</code>".</p>
1306:
1307: <p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1308: scripts in Web applications, and does not necessarily imply the
1309: existence of an actual <code>Document</code> object or of any other
1310: <code>Node</code> objects as defined in the DOM Core
1.327 ihickson 1311: specifications. <a href="#refsDOMCORE">[DOMCORE]</a></p>
1312:
1313: <p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1314: being retrieved (e.g. by author script), and is said to be
1.327 ihickson 1315: <em>setting</em> when a new value is assigned to it.</p>
1316:
1317:
1318: <p>The term "JavaScript" is used to refer to ECMA262, rather than
1.103 ihickson 1319: the official term ECMAScript, since the term JavaScript is more
1.327 ihickson 1320: widely known. <a href="#refsECMA262">[ECMA262]</a></p>
1321:
1322:
1323:
1324: <h2 id="infrastructure"><span class="secno">4 </span>Infrastructure</h2>
1325:
1326: <p>There are two kinds of workers; dedicated workers, and shared
1.81 ihickson 1327: workers. Dedicated workers, once created, and are linked to their
1328: creator; but message ports can be used to communicate from a
1329: dedicated worker to multiple other browsing contexts or
1330: workers. Shared workers, on the other hand, are named, and once
1331: created any script running in the same <span>origin</span> can
1.327 ihickson 1332: obtain a reference to that worker and communicate with it.</p>
1333:
1334:
1335: <h3 id="dependencies-0"><span class="secno">4.1 </span>Dependencies</h3>
1336: <p>The <dfn id="messageport"><code>MessagePort</code></dfn> interface is defined in
1337: the HTML specification. <a href="#refsHTML">[HTML]</a></p>
1338:
1339:
1340:
1341: <h3 id="the-global-scope"><span class="secno">4.2 </span>The global scope</h3>
1342:
1343: <p>The global scope is the "inside" of a worker.</p>
1344:
1345: <h4 id="the-workerglobalscope-common-interface"><span class="secno">4.2.1 </span>The <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> common interface</h4>
1346:
1347: <pre class="idl">interface <dfn id="workerglobalscope">WorkerGlobalScope</dfn> : <span>EventTarget</span> {
1.115 ihickson 1348: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1349: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1350:
1351: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.332 ihickson 1352: attribute <span>EventHandler</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1353: attribute <span>EventHandler</span> <a href="#handler-workerglobalscope-onoffline" title="handler-WorkerGlobalScope-onoffline">onoffline</a>;
1354: attribute <span>EventHandler</span> <a href="#handler-workerglobalscope-ononline" title="handler-WorkerGlobalScope-ononline">ononline</a>;
1.150 ihickson 1355: };
1.327 ihickson 1356: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <a href="#workerutils">WorkerUtils</a>;</pre>
1357:
1358: <p>The <dfn id="dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self"><code>self</code></dfn> attribute
1359: must return the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.</p>
1360:
1361: <p>The <dfn id="dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location"><code>location</code></dfn>
1.115 ihickson 1362: attribute must return the <code><a href="#workerlocation">WorkerLocation</a></code> object created
1363: for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object when the worker was
1.81 ihickson 1364: created. It represents the <span>absolute URL</span> of the script
1.327 ihickson 1365: that was used to initialize the worker, after any redirects.</p>
1366:
1367: <hr><p>When a script invokes the <dfn id="dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close"><code>close()</code></dfn>
1.123 ihickson 1368: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent
1.327 ihickson 1369: must run the following steps (atomically):</p>
1370:
1371: <ol><li><p>Discard any <span title="concept-task">tasks</span> that
1.123 ihickson 1372: have been added to the <span>event loop</span>'s <span title="task
1373: queue">task queues</span>.</p>
1374:
1.81 ihickson 1375:
1.318 ihickson 1376:
1.115 ihickson 1377: <li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1378: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.123 ihickson 1379: true. (This prevents any further tasks from being queued.)</li>
1.81 ihickson 1380:
1.177 ihickson 1381: </ol><p>The following are the <span>event handlers</span> (and their
1382: corresponding <span title="event handler event type">event handler
1383: event types</span>) that must be supported, as IDL attributes, by
1384: objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.327 ihickson 1385: interface:</p>
1386:
1387: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.281 ihickson 1388: <tbody><tr><td><dfn id="handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.289 ihickson 1389: <tr><td><dfn id="handler-workerglobalscope-onoffline" title="handler-WorkerGlobalScope-onoffline"><code>onoffline</code></dfn> <td> <code title="event-offline">offline</code>
1390: <tr><td><dfn id="handler-workerglobalscope-ononline" title="handler-WorkerGlobalScope-ononline"><code>ononline</code></dfn> <td> <code title="event-online">online</code>
1.327 ihickson 1391: </table><h4 id="dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.2.2 </span>Dedicated workers and the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> interface</h4>
1392:
1393: <pre class="idl">interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.318 ihickson 1394: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(any message, optional sequence<<span>Transferable</span>> transfer);
1.332 ihickson 1395: attribute <span>EventHandler</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.327 ihickson 1396: };</pre>
1397:
1398: <p>The <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> interface must not
1.316 ihickson 1399: exist if the interface's <span>relevant namespace object</span> is
1.327 ihickson 1400: not a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1401:
1402: <p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they
1.301 ihickson 1403: had an implicit <code><a href="#messageport">MessagePort</a></code> associated with them. This
1.81 ihickson 1404: port is part of a channel that is set up when the worker is created,
1405: but it is not exposed. This object must never be garbage collected
1.327 ihickson 1406: before the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.</p>
1407:
1408: <p>All messages received by that port must immediately be retargeted
1409: at the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.</p>
1410:
1411: <p>The <dfn id="dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage"><code>postMessage()</code></dfn>
1.318 ihickson 1412: method on
1.115 ihickson 1413: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when
1.281 ihickson 1414: invoked, it immediately invoked the
1.81 ihickson 1415: method of the same name on the port, with the same arguments, and
1.327 ihickson 1416: returned the same return value.</p>
1417:
1418: <p>The following are the <span>event handlers</span> (and their
1.177 ihickson 1419: corresponding <span title="event handler event type">event handler
1420: event types</span>) that must be supported, as IDL attributes, by
1421: objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1.327 ihickson 1422: interface:</p>
1423:
1424: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1425: <tbody><tr><td><dfn id="handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1.191 ihickson 1426: </table><p>For the purposes of the <span>application cache</span> networking
1427: model, a dedicated worker is an extension of the <span>cache
1.327 ihickson 1428: host</span> from which it was created.</p>
1429:
1430:
1431:
1432: <h4 id="shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.2.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> interface</h4>
1433:
1434: <pre class="idl">interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1435: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1436: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.332 ihickson 1437: attribute <span>EventHandler</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.327 ihickson 1438: };</pre>
1439:
1440: <p>The <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> interface must not
1.316 ihickson 1441: exist if the interface's <span>relevant namespace object</span> is
1.327 ihickson 1442: not a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1443:
1444: <p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on
1445: their global object for each connection.</p>
1446:
1447: <p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn>
1.81 ihickson 1448: attribute must return the value it was assigned when the
1.115 ihickson 1449: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1450: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name
1.81 ihickson 1451: that can be used to obtain a reference to the worker using the
1.327 ihickson 1452: <code><a href="#sharedworker">SharedWorker</a></code> constructor.</p>
1453:
1454: <p>The following are the <span>event handlers</span> (and their
1.177 ihickson 1455: corresponding <span title="event handler event type">event handler
1456: event types</span>) that must be supported, as IDL attributes, by
1457: objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1.327 ihickson 1458: interface:</p>
1459:
1460: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1461: <tbody><tr><td><dfn id="handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect"><code>onconnect</code></dfn> <td> <code title="event-connect">connect</code>
1.191 ihickson 1462: </table><p>For the purposes of the <span>application cache</span> networking
1463: model, a shared worker is its own <span>cache host</span>. The
1464: <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1.327 ihickson 1465: worker with an <span>application cache</span>.</p>
1466:
1467: <p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code>
1.123 ihickson 1468: attribute returns the <code>ApplicationCache</code> object for the
1.327 ihickson 1469: worker.</p>
1470:
1471:
1472: <h3 id="origins-of-workers"><span class="secno">4.3 </span>Origins of workers</h3>
1473:
1474: <p>Both the <span>origin</span> and <span>effective script
1.81 ihickson 1475: origin</span> of scripts running in workers are the
1476: <span>origin</span> of the <span>absolute URL</span> given in that
1.115 ihickson 1477: the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
1.327 ihickson 1478: represents.</p>
1479:
1480:
1481:
1482: <h3 id="the-event-loop"><span class="secno">4.4 </span>The event loop</h3>
1483:
1484: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object has an <span>event
1.128 ihickson 1485: loop</span> distinct from those defined for <span title="unit of
1486: related similar-origin browsing contexts">units of related
1487: similar-origin browsing contexts</span>. This <span>event
1488: loop</span> has no associated <span>browsing context</span>, and its
1489: <span title="task queue">task queues</span> only have events,
1490: callbacks, and networking activity as <span title="concept-task">tasks</span>. The processing model of these
1491: <span title="event loop">event loops</span> is defined below in the
1.327 ihickson 1492: <a href="#run-a-worker">run a worker</a> algorithm.</p>
1493:
1494: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object also has a <dfn id="dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</dfn> flag, which must
1.81 ihickson 1495: initially be false, but which can get set to true by the algorithms
1.327 ihickson 1496: in the processing model section below.</p>
1497:
1498: <p>Once the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set to
1.81 ihickson 1499: true, the <span>event loop</span>'s <span title="task queue">task
1.115 ihickson 1500: queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks
1.175 ihickson 1501: already on the queue are unaffected except where otherwise
1.115 ihickson 1502: specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true,
1.81 ihickson 1503: timers stop firing, notifications for all pending asynchronous
1.327 ihickson 1504: operations are dropped, etc.</p>
1505:
1506:
1507:
1508: <h3 id="the-worker-s-lifetime"><span class="secno">4.5 </span>The worker's lifetime</h3>
1509:
1510: <p>Workers communicate with other workers and with <span title="browsing context">browsing contexts</span> through <span title="channel messaging">message channels</span> and their
1511: <code><a href="#messageport">MessagePort</a></code> objects.</p>
1512:
1513: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global
1.124 ihickson 1514: scope</var> has a list of <dfn id="the-worker-s-ports">the worker's ports</dfn>, which
1.301 ihickson 1515: consists of all the <code><a href="#messageport">MessagePort</a></code> objects that are
1.81 ihickson 1516: entangled with another port and that have one (but only one) port
1517: owned by <var title="">worker global scope</var>. This list includes
1.281 ihickson 1518: the implicit
1.327 ihickson 1519: <code><a href="#messageport">MessagePort</a></code> in the case of <a href="#dedicatedworkerglobalscope" title="DedicatedWorkerGlobalScope">dedicated workers</a>.</p>
1520:
1521: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> also has a list of <dfn id="the-worker-s-workers">the
1.124 ihickson 1522: worker's workers</dfn>. Initially this list is empty; it is
1.327 ihickson 1523: populated when the worker creates or obtains further workers.</p>
1524:
1525: <p>Finally, each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> also has a list of
1.124 ihickson 1526: <dfn id="the-worker-s-documents">the worker's <code>Document</code>s</dfn>. Initially this list
1.327 ihickson 1527: is empty; it is populated when the worker is created.</p>
1528:
1529: <p>Whenever a <code>Document</code> <var title="">d</var> is <dfn id="add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">added to the
1.123 ihickson 1530: worker's <code>Document</code>s</dfn>, the user agent must, for each
1.325 ihickson 1531: worker <var title="">q</var> in the list of <a href="#the-worker-s-workers">the worker's
1532: workers</a> whose list of <a href="#the-worker-s-documents">the worker's
1533: <code>Document</code>s</a> does not contain <var title="">d</var>, <a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's
1.123 ihickson 1534: documents">add <var title="">d</var> to <var title="">q</var>'s
1535: <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.327 ihickson 1536: <code>Document</code>s</span></a>.</p>
1537:
1538: <p>Whenever a <code>Document</code> object is <span title="discard a
1.123 ihickson 1539: Document">discarded</span>, it must be removed from the list of
1540: <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each worker
1.327 ihickson 1541: whose list contains that <code>Document</code>.</p>
1542:
1543: <p>Given a <span>script's global object</span> <var title="">o</var>
1.123 ihickson 1544: when creating or obtaining a worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant
1545: <code>Document</code> objects to add</dfn> depends on the type of
1546: <var title="">o</var>. If <var title="">o</var> is a
1547: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we are creating a
1548: nested worker), then the relevant <code>Document</code>s are the
1549: <code>Document</code>s that are in <var title="">o</var>'s own list
1550: of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a>. Otherwise, <var title="">o</var> is a <code>Window</code> object, and the relevant
1551: <code>Document</code> is just the <code>Document</code> that is the
1.327 ihickson 1552: <span>active document</span> of the <code>Window</code> object <var title="">o</var>.</p>
1553:
1554: <hr><p>A worker is said to be a <dfn id="permissible-worker">permissible worker</dfn> if its
1.123 ihickson 1555: list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> is not
1.327 ihickson 1556: empty.</p>
1557:
1558: <p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is a
1.123 ihickson 1559: <a href="#permissible-worker">permissible worker</a> and either it has outstanding
1560: timers, database transactions, or network connections, or its list
1.124 ihickson 1561: of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its
1.123 ihickson 1562: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> is actually a
1563: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.327 ihickson 1564: shared worker).</p>
1565:
1566: <p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any
1.123 ihickson 1567: of the <code>Document</code> objects in <a href="#the-worker-s-documents">the worker's
1.327 ihickson 1568: <code>Document</code>s</a> are <span>fully active</span>.</p>
1569:
1570: <p>A worker is said to be a <dfn id="suspendable-worker">suspendable worker</dfn> if it is
1.123 ihickson 1571: not an <a href="#active-needed-worker">active needed worker</a> but it is a
1.327 ihickson 1572: <a href="#permissible-worker">permissible worker</a>.</p>
1573:
1574:
1575: <h3 id="processing-model"><span class="secno">4.6 </span>Processing model</h3>
1576:
1577: <p>When a user agent is to <dfn id="run-a-worker">run a worker</dfn> for a script with
1.232 ihickson 1578: <span>URL</span> <var title="">url</var>, a <span>browsing
1579: context</span> <var title="">owner browsing context</var>, a
1580: <code>Document</code> <var title="">owner document</var>, an
1581: <span>origin</span> <var title="">owner origin</var>, and with
1582: global scope <var title="">worker global scope</var>, it must run
1.327 ihickson 1583: the following steps:</p>
1584:
1585: <ol><li>
1.81 ihickson 1586:
1.274 ihickson 1587: <p>Create a separate parallel execution environment (i.e. a
1588: separate thread or process or equivalent construct), and run the
1589: rest of these steps asynchronously in that context.</p>
1.81 ihickson 1590:
1591: </li>
1.4 ihickson 1592:
1.101 ihickson 1593: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1594: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
1.101 ihickson 1595: shared worker), and there are any <span title="relevant application
1596: cache">relevant application caches</span> that are identified by a
1597: manifest URL with the <span>same origin</span> as <var title="">url</var> and that have <var title="">url</var> as one of
1.115 ihickson 1598: their entries, <em>not</em> excluding entries marked as <span title="concept-appcache-foreign">foreign</span>, then associate the
1599: <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most appropriate application
1.101 ihickson 1600: cache</span> of those that match.</li>
1601:
1.4 ihickson 1602: <li>
1.52 ihickson 1603:
1.256 ihickson 1604: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <var title="">owner origin</var>,
1605: with the <i>synchronous flag</i> set and the <i>force same-origin
1.281 ihickson 1606: flag</i> set.</p>
1.318 ihickson 1607:
1.256 ihickson 1608: <p>If the attempt fails, then for each <code><a href="#worker">Worker</a></code> or
1609: <code><a href="#sharedworker">SharedWorker</a></code> object associated with <var title="">worker global scope</var>, <span>queue a task</span> to
1610: <span>fire a simple event</span> named <code title="event-error">error</code> at that object. Abort these
1611: steps.</p>
1.7 ihickson 1612:
1.264 ihickson 1613: <p>If the attempt succeeds, then let <var title="">source</var> be
1614: the script resource <span>decoded as UTF-8, with error
1615: handling</span>.
1616:
1617: <a href="#refsHTML">[HTML]</a>
1618:
1619: </p>
1.81 ihickson 1620:
1.68 ihickson 1621: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1622:
1.115 ihickson 1623: <p class="note">As with <code>script</code> elements, the MIME
1.81 ihickson 1624: type of the script is ignored. Unlike with <code>script</code>
1625: elements, there is no way to override the type. It's always
1.170 ihickson 1626: assumed to be JavaScript.</p>
1.81 ihickson 1627:
1628: </li>
1.7 ihickson 1629:
1630: <li>
1.68 ihickson 1631:
1.115 ihickson 1632: <p>A new <span title="concept-script">script</span> is now
1.81 ihickson 1633: created, as follows.</p>
1634:
1635: <p>Create a new <span>script execution environment</span>
1636: set up as appropriate for the scripting language <var title="">language</var>.</p>
1.34 ihickson 1637:
1.68 ihickson 1638: <p>Parse/compile/initialize <var title="">source</var> using that
1.81 ihickson 1639: <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
1640: entry-points</span>; set the <i>initial code entry-point</i> to
1641: the entry-point for any executable code to be immediately run.</p>
1642:
1643: <p>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</p>
1644:
1645: <p>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</p>
1646:
1.232 ihickson 1647: <p>Set the <span>script's document</span> to <var title="">owner
1648: document</var>.</p>
1649:
1.83 ihickson 1650: <p>Set the <span>script's URL character encoding</span> to
1.81 ihickson 1651: UTF-8. (This is just used for encoding non-ASCII characters in the
1652: query component of URLs.)</p>
1.68 ihickson 1653:
1654: <p>Set the <span>script's base URL</span> to <var title="">url</var>.</p>
1.4 ihickson 1655:
1.81 ihickson 1656: </li>
1.4 ihickson 1657:
1658: <li>
1.81 ihickson 1659:
1660: <p><strong>Closing orphan workers</strong>: Start monitoring the
1.125 ihickson 1661: worker such that no sooner than it stops being either a
1662: <a href="#protected-worker">protected worker</a> or a <a href="#suspendable-worker">suspendable
1.123 ihickson 1663: worker</a>, and no later than it stops being a
1664: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global
1665: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1.281 ihickson 1666: to true.</p>
1.81 ihickson 1667:
1668: </li>
1.9 ihickson 1669:
1670: <li>
1.7 ihickson 1671:
1.81 ihickson 1672: <p><strong>Suspending workers</strong>: Start monitoring the
1673: worker, such that whenever <var title="">worker global
1.115 ihickson 1674: scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false
1675: and the worker is a <a href="#suspendable-worker">suspendable worker</a>, the user
1.81 ihickson 1676: agent suspends execution of script in that worker until such time
1.115 ihickson 1677: as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag switches
1678: to true or the worker stops being a <a href="#suspendable-worker">suspendable
1.81 ihickson 1679: worker</a>.</p>
1.4 ihickson 1680:
1.81 ihickson 1681: </li>
1.68 ihickson 1682:
1683: <li>
1.4 ihickson 1684:
1.81 ihickson 1685: <p><span title="jump to a code entry-point">Jump</span> to the
1.115 ihickson 1686: <span title="concept-script">script</span>'s <i>initial code
1.81 ihickson 1687: entry-point</i>, and let that run until it either returns, fails
1688: to catch an exception, or gets prematurely aborted by the
1.115 ihickson 1689: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1690: algorithms defined below.</p>
1691:
1.4 ihickson 1692:
1.318 ihickson 1693:
1.81 ihickson 1694: </li>
1.4 ihickson 1695:
1.95 ihickson 1696: <li><p>If <var title="">worker global scope</var> is actually a
1.115 ihickson 1697: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
1.126 ihickson 1698: a dedicated worker), then enable the <span>port message
1699: queue</span> of the worker's implicit port.</li>
1.95 ihickson 1700:
1.4 ihickson 1701: <li>
1.68 ihickson 1702:
1.115 ihickson 1703: <p><i title="">Event loop</i>: Wait until either there is a <span title="concept-task">task</span> in one of the <span>event
1704: loop</span>'s <span title="task queue">task queues</span> or <var title="">worker global scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1.81 ihickson 1705: to true.</p>
1.43 ihickson 1706:
1.81 ihickson 1707: </li>
1.4 ihickson 1708:
1709: <li>
1710:
1.81 ihickson 1711: <p>Run the oldest task on one of the <span>event loop</span>'s
1712: <span title="task queue">task queues</span>, if any. The user
1713: agent may pick any <span>task queue</span>.</p>
1714:
1.115 ihickson 1715: <p class="note">The handling of events or the execution of
1716: callbacks might get prematurely aborted by the "<a href="#kill-a-worker">kill a
1717: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1718: defined below.</p>
1.8 ihickson 1719:
1.81 ihickson 1720: </li>
1.4 ihickson 1721:
1722: <li>
1723:
1.248 ihickson 1724: <p>If the <span>storage mutex</span> is now owned by the worker's
1725: <span>event loop</span>, release it so that it is once again
1726: free.</p>
1727:
1728: </li>
1729:
1730: <li>
1731:
1732: <p>Remove the task just run in the earlier step, if any, from its
1.81 ihickson 1733: <span>task queue</span>.</p>
1.4 ihickson 1734:
1.81 ihickson 1735: </li>
1.4 ihickson 1736:
1737: <li>
1.8 ihickson 1738:
1.81 ihickson 1739: <p>If there are any more events in the <span>event loop</span>'s
1.115 ihickson 1740: <span title="task queue">task queues</span> or if <var title="">worker global scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set
1.81 ihickson 1741: to false, then jump back to the step above labeled <i>event
1742: loop</i>.</p>
1.8 ihickson 1743:
1.81 ihickson 1744: </li>
1.8 ihickson 1745:
1746: <li>
1.71 ihickson 1747:
1.123 ihickson 1748: <p>Empty the <var title="">worker global scope</var>'s <span>list
1.333 ! ihickson 1749: of active timers</span>.</p>
1.50 ihickson 1750:
1.81 ihickson 1751: </li>
1.50 ihickson 1752:
1.247 ihickson 1753: <li>
1754:
1755: <p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's
1756: ports</a>.</p>
1757:
1758: </li>
1759:
1.318 ihickson 1760:
1.155 ihickson 1761: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must
1.81 ihickson 1762: run the following steps in parallel with the worker's main loop (the
1.327 ihickson 1763: "<a href="#run-a-worker">run a worker</a>" processing model defined above):</p>
1764:
1765: <ol><li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1766: true.</li>
1767:
1768:
1.318 ihickson 1769:
1.115 ihickson 1770: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1771: queued in the <span>event loop</span>'s <span title="task
1.281 ihickson 1772: queue">task queues</span>, discard them without processing them.</li>
1773:
1.81 ihickson 1774:
1.318 ihickson 1775:
1.81 ihickson 1776: <li><p>Wait a user-agent-defined amount of time.</li>
1777:
1.281 ihickson 1778: <li><p>Abort the script currently running in the worker.</li>
1.81 ihickson 1779:
1.155 ihickson 1780: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>"
1.81 ihickson 1781: processing model on a worker at any time, e.g. in response to user
1782: requests, in response to CPU quota management, or when a worker
1.115 ihickson 1783: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker
1784: continues executing even after its <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was
1.327 ihickson 1785: set to true.</p>
1786:
1787: <hr><p>When a user agent is to <dfn id="terminate-a-worker">terminate a worker</dfn> it must run
1.81 ihickson 1788: the following steps in parallel with the worker's main loop (the
1.327 ihickson 1789: "<a href="#run-a-worker">run a worker</a>" processing model defined above):</p>
1790:
1791: <ol><li><p>Set the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's
1.115 ihickson 1792: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag to
1.81 ihickson 1793: true.</li>
1794:
1.115 ihickson 1795: <li><p>If there are any <span title="concept-task">tasks</span>
1.81 ihickson 1796: queued in the <span>event loop</span>'s <span title="task
1797: queue">task queues</span>, discard them without processing
1798: them.</li>
1799:
1800: <li><p>Abort the script currently running in the worker.</li>
1801:
1.115 ihickson 1802: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is
1803: actually a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the
1.81 ihickson 1804: worker is a dedicated worker), then empty the <span>port message
1805: queue</span> of the port that the worker's implicit port is
1806: entangled with.</li>
1807:
1.155 ihickson 1808: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the
1.327 ihickson 1809: <span>DOM manipulation task source</span>.</p>
1810:
1811:
1812: <h3 id="runtime-script-errors"><span class="secno">4.7 </span>Runtime script errors</h3>
1813:
1814: <p>Whenever an uncaught runtime script error occurs in one of the
1.143 ihickson 1815: worker's scripts, if the error did not occur while handling a
1816: previous script error, the user agent must <span>report the
1.314 ihickson 1817: error</span> at the <span>URL</span> of the resource that contained
1.324 ihickson 1818: the script, with the position (line number and column number) where
1819: the error occurred, in the <span>origin</span> of the scripts
1820: running in the worker, using the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1821: object's <code title="handler-WorkerGlobalScope-onerror"><a href="#handler-workerglobalscope-onerror">onerror</a></code> attribute.
1.205 ihickson 1822:
1.226 ihickson 1823: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1824:
1.327 ihickson 1825: </p>
1826:
1.205 ihickson 1827: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1828: the error occurred while handling a previous script error, the error
1.215 ihickson 1829: may be reported to the user.
1.205 ihickson 1830:
1.226 ihickson 1831: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1832:
1.327 ihickson 1833: </p>
1834:
1.205 ihickson 1835: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not handled</i> afterwards, or if
1.132 ihickson 1836: the error occurred while handling a previous script error, the user
1.292 ihickson 1837: agent must <span>queue a task</span> to fire an event that uses the
1838: <code><a href="#errorevent">ErrorEvent</a></code> interface, with the name <code title="event-error">error</code>, that doesn't bubble and is
1.307 ihickson 1839: cancelable, with its <code title="dom-ErrorEvent-message"><a href="#dom-errorevent-message">message</a></code>, <code title="dom-ErrorEvent-filename"><a href="#dom-errorevent-filename">filename</a></code>, and <code title="dom-ErrorEvent-lineno"><a href="#dom-errorevent-lineno">lineno</a></code> attributes initialized
1.292 ihickson 1840: appropriately, at the <code><a href="#worker">Worker</a></code> object associated with the
1.307 ihickson 1841: worker. If the event is not canceled, the user agent must act as if
1842: the uncaught runtime script error had occurred in the global scope
1843: that the <code><a href="#worker">Worker</a></code> object is in, thus repeating the entire
1.327 ihickson 1844: runtime script error reporting process one level up.</p>
1845:
1846: <p>If the implicit port connecting the worker to its
1.292 ihickson 1847: <code><a href="#worker">Worker</a></code> object has been disentangled (i.e. if the parent
1848: worker has been terminated), then the user agent must act as if the
1849: <code><a href="#worker">Worker</a></code> object had no <code title="event-error">error</code> event handler and as if that
1850: worker's <code title="handler-WorkerGlobalScope-onerror"><a href="#handler-workerglobalscope-onerror">onerror</a></code> attribute
1.327 ihickson 1851: was null, but must otherwise act as described above.</p>
1852:
1.331 ihickson 1853: <p class="note">Thus, error reports propagate up to the chain of
1.292 ihickson 1854: dedicated workers up to the original <code>Document</code>, even if
1855: some of the workers along this chain have been terminated and
1.327 ihickson 1856: garbage collected.</p>
1857:
1858: <p>The <span>task source</span> for the task mentioned above is the
1859: <span>DOM manipulation task source</span>.</p>
1860:
1861: <hr><pre class="idl">[Constructor(DOMString type, optional <a href="#erroreventinit">ErrorEventInit</a> eventInitDict)]
1.307 ihickson 1862: interface <dfn id="errorevent">ErrorEvent</dfn> : <span>Event</span> {
1.147 ihickson 1863: readonly attribute DOMString <a href="#dom-errorevent-message" title="dom-ErrorEvent-message">message</a>;
1864: readonly attribute DOMString <a href="#dom-errorevent-filename" title="dom-ErrorEvent-filename">filename</a>;
1.115 ihickson 1865: readonly attribute unsigned long <a href="#dom-errorevent-lineno" title="dom-ErrorEvent-lineno">lineno</a>;
1.307 ihickson 1866: };
1867:
1868: dictionary <dfn id="erroreventinit">ErrorEventInit</dfn> : <span>EventInit</span> {
1869: DOMString message;
1870: DOMString filename;
1871: unsigned long lineno;
1.327 ihickson 1872: };</pre>
1873:
1874: <p>The <dfn id="dom-errorevent-message" title="dom-ErrorEvent-message"><code>message</code></dfn> attribute
1.307 ihickson 1875: must return the value it was initialized to. When the object is
1876: created, this attribute must be initialized to the empty string. It
1.327 ihickson 1877: represents the error message.</p>
1878:
1879: <p>The <dfn id="dom-errorevent-filename" title="dom-ErrorEvent-filename"><code>filename</code></dfn>
1.307 ihickson 1880: attribute must return the value it was initialized to. When the
1881: object is created, this attribute must be initialized to the empty
1882: string. It represents the <span>absolute URL</span> of the script in
1.327 ihickson 1883: which the error originally occurred.</p>
1884:
1885: <p>The <dfn id="dom-errorevent-lineno" title="dom-ErrorEvent-lineno"><code>lineno</code></dfn>
1.307 ihickson 1886: attribute must return the value it was initialized to. When the
1887: object is created, this attribute must be initialized to zero. It
1888: represents the line number where the error occurred in the
1.327 ihickson 1889: script.</p>
1890:
1891:
1892:
1893: <h3 id="creating-workers"><span class="secno">4.8 </span>Creating workers</h3>
1894:
1895: <h4 id="the-abstractworker-abstract-interface"><span class="secno">4.8.1 </span>The <code><a href="#abstractworker">AbstractWorker</a></code> abstract interface</h4>
1896:
1897: <pre class="idl">[NoInterfaceObject]
1.317 ihickson 1898: interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.332 ihickson 1899: attribute <span>EventHandler</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1.318 ihickson 1900:
1.327 ihickson 1901: };</pre>
1902:
1903: <p>The following are the <span>event handlers</span> (and their
1.177 ihickson 1904: corresponding <span title="event handler event type">event handler
1905: event types</span>) that must be supported, as IDL attributes, by
1.327 ihickson 1906: objects implementing the <code><a href="#abstractworker">AbstractWorker</a></code> interface:</p>
1907:
1908: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1909: <tbody><tr><td><dfn id="handler-abstractworker-onerror" title="handler-AbstractWorker-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.318 ihickson 1910:
1.327 ihickson 1911: </table><h4 id="dedicated-workers-and-the-worker-interface"><span class="secno">4.8.2 </span>Dedicated workers and the <code><a href="#worker">Worker</a></code> interface</h4>
1912:
1913: <pre class="idl">[<a href="#dom-worker" title="dom-Worker">Constructor</a>(DOMString scriptURL)]
1.317 ihickson 1914: interface <dfn id="worker">Worker</dfn> : <span>EventTarget</span> {
1.115 ihickson 1915: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1916:
1.318 ihickson 1917: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(any message, optional sequence<<span>Transferable</span>> transfer);
1.332 ihickson 1918: attribute <span>EventHandler</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.317 ihickson 1919: };
1.327 ihickson 1920: <a href="#worker">Worker</a> implements <a href="#abstractworker">AbstractWorker</a>;</pre>
1921:
1922: <p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method,
1.115 ihickson 1923: when invoked, must cause the "<a href="#terminate-a-worker">terminate a worker</a>"
1.81 ihickson 1924: algorithm to be run on the worker with with the object is
1.327 ihickson 1925: associated.</p>
1926:
1927: <p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit
1.301 ihickson 1928: <code><a href="#messageport">MessagePort</a></code> associated with them. This port is part of
1.81 ihickson 1929: a channel that is set up when the worker is created, but it is not
1930: exposed. This object must never be garbage collected before the
1.327 ihickson 1931: <code><a href="#worker">Worker</a></code> object.</p>
1932:
1933: <p>All messages received by that port must immediately be retargeted
1934: at the <code><a href="#worker">Worker</a></code> object.</p>
1935:
1936: <p>The <dfn id="dom-worker-postmessage" title="dom-Worker-postMessage"><code>postMessage()</code></dfn>
1.318 ihickson 1937: method on <code><a href="#worker">Worker</a></code> objects
1.281 ihickson 1938: must act as if, when invoked, it
1.81 ihickson 1939: immediately invoked the method of the same name on the port, with
1.327 ihickson 1940: the same arguments, and returned the same return value.</p>
1941:
1942: <div class="example">
1.319 ihickson 1943:
1944: <p>The <code title="dom-Worker-postMessage"><a href="#dom-worker-postmessage">postMessage()</a></code>
1945: method's first argument can be structured data:</p>
1946:
1947: <pre>worker.postMessage({opcode: 'activate', device: 1938, parameters: [23, 102]});</pre>
1948:
1.327 ihickson 1949: </div>
1950:
1951: <p>The following are the <span>event handlers</span> (and their
1.177 ihickson 1952: corresponding <span title="event handler event type">event handler
1953: event types</span>) that must be supported, as IDL attributes, by
1.327 ihickson 1954: objects implementing the <code><a href="#worker">Worker</a></code> interface:</p>
1955:
1956: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1957: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1958: </table><hr><p>When the <dfn id="dom-worker" title="dom-Worker"><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
1.327 ihickson 1959: user agent must run the following steps:</p>
1960:
1961: <ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument relative to the <span>entry
1.133 ihickson 1962: script</span>'s <span title="script's base URL">base URL</span>,
1963: when the method is invoked.</li>
1.9 ihickson 1964:
1.309 ihickson 1965: <li><p>If this fails, throw a <code>SyntaxError</code>
1.81 ihickson 1966: exception.</li>
1.9 ihickson 1967:
1.167 ihickson 1968: <li>
1969:
1970: <p>If the <span>origin</span> of the resulting <span>absolute
1971: URL</span> is not the <span title="same origin">same</span> as the
1.216 ihickson 1972: origin of the <span>entry script</span>, then throw a
1.309 ihickson 1973: <code>SecurityError</code> exception.</p>
1.167 ihickson 1974:
1975: <p class="note">Thus, scripts must be external files with the same
1.269 ihickson 1976: scheme as the original page: you can't load a script from a <span title="data protocol"><code title="">data:</code> URL</span> or
1977: <span title="javascript protocol"><code title="">javascript:</code> URL</span>, and an <code>http:</code>
1978: page couldn't start workers using scripts with <code>http:</code>
1979: URLs.</p>
1.167 ihickson 1980:
1981: </li>
1.9 ihickson 1982:
1.185 ihickson 1983: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1984: object. Let <var title="">worker global scope</var> be this new
1985: object.</li>
1.9 ihickson 1986:
1.115 ihickson 1987: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with
1.81 ihickson 1988: <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</li>
1.50 ihickson 1989:
1.301 ihickson 1990: <li><p><span>Create a new <code><a href="#messageport">MessagePort</a></code> object</span>
1.192 ihickson 1991: owned by the <span title="script's global object">global
1992: object</span> of the <span title="concept-script">script</span> that
1.185 ihickson 1993: invoked the constructor. Let this be the <var title="">outside
1.81 ihickson 1994: port</var>.</li>
1.9 ihickson 1995:
1.81 ihickson 1996: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1997:
1.301 ihickson 1998: <li><p><span>Create a new <code><a href="#messageport">MessagePort</a></code> object</span>
1.185 ihickson 1999: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 2000:
1.81 ihickson 2001: <li><p>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</li>
1.50 ihickson 2002:
1.81 ihickson 2003: <li><p><span>Entangle</span> <var title="">outside port</var> and
2004: <var title="">inside port</var>.</li>
1.50 ihickson 2005:
1.81 ihickson 2006: <li><p>Return <var title="">worker</var>, and run the following
2007: steps asynchronously.</li>
1.50 ihickson 2008:
2009:
1.318 ihickson 2010:
1.126 ihickson 2011: <li><p>Enable <var title="">outside port</var>'s <span>port message
1.81 ihickson 2012: queue</span>.</li>
1.50 ihickson 2013:
2014: <li>
1.51 ihickson 2015:
1.123 ihickson 2016: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 2017: <code>Document</code> objects to add</a> given the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.123 ihickson 2018: constructor.</p>
2019:
2020: </li>
2021:
2022: <li>
2023:
2024: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
2025: <var title="">worker global scope</var>'s list of <span>the
2026: worker's <code>Document</code>s</span></a> the
2027: <code>Document</code> objects in <var title="">docs</var>.</p>
2028:
2029: </li>
2030:
2031: <li>
2032:
1.192 ihickson 2033: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 2034: of the <span title="concept-script">script</span> that invoked the
2035: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we
2036: are creating a nested worker), add <var title="">worker global
2037: scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1.192 ihickson 2038: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object that is the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.124 ihickson 2039: constructor.</p>
2040:
2041: </li>
2042:
2043: <li>
2044:
1.115 ihickson 2045: <p><a href="#run-a-worker">Run a worker</a> for the resulting <span>absolute
1.193 ihickson 2046: URL</span>, with the <span>script's browsing context</span> of the
1.81 ihickson 2047: script that invoked the method as the <var title="">owner browsing
1.232 ihickson 2048: context</var>, with the <span>script's document</span> of the
2049: script that invoked the method as the <var title="">owner
2050: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 2051: script</span> as the <var title="">owner origin</var>, and with
2052: <var title="">worker global scope</var> as the global scope.</p>
1.9 ihickson 2053:
1.81 ihickson 2054: </li>
1.4 ihickson 2055:
1.155 ihickson 2056: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 2057: object</span> is either a <code>Window</code> object or an object
1.327 ihickson 2058: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.</p>
2059:
2060:
2061: <h4 id="shared-workers-and-the-sharedworker-interface"><span class="secno">4.8.3 </span>Shared workers and the <code><a href="#sharedworker">SharedWorker</a></code> interface</h4>
2062:
2063: <pre class="idl">[<a href="#dom-sharedworker" title="dom-SharedWorker">Constructor</a>(DOMString scriptURL, optional DOMString name)]
1.317 ihickson 2064: interface <dfn id="sharedworker">SharedWorker</dfn> : <span>EventTarget</span> {
1.301 ihickson 2065: readonly attribute <a href="#messageport">MessagePort</a> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.317 ihickson 2066: };
1.327 ihickson 2067: <a href="#sharedworker">SharedWorker</a> implements <a href="#abstractworker">AbstractWorker</a>;</pre>
2068:
2069: <p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn>
1.81 ihickson 2070: attribute must return the value it was assigned by the object's
1.301 ihickson 2071: constructor. It represents the <code><a href="#messageport">MessagePort</a></code> for
1.327 ihickson 2072: communicating with the shared worker.</p>
2073:
2074: <p>When the <dfn id="dom-sharedworker" title="dom-SharedWorker"><code>SharedWorker(<var title="">scriptURL</var>, <var title="">name</var>)</code></dfn>
1.81 ihickson 2075: constructor is invoked, the user agent must run the following
1.327 ihickson 2076: steps:</p>
2077:
2078: <ol><li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</li>
1.81 ihickson 2079:
1.309 ihickson 2080: <li><p>If this fails, throw a <code>SyntaxError</code>
1.81 ihickson 2081: exception.</li>
2082:
1.159 ihickson 2083: <li><p>Otherwise, let <var title="">scriptURL</var> be the
2084: resulting <span>absolute URL</span>.</li>
2085:
2086: <li><p>Let <var title="">name</var> be the value of the second
1.164 ihickson 2087: argument, or the empty string if the second argument was
2088: omitted.</li>
1.159 ihickson 2089:
1.167 ihickson 2090: <li>
2091:
2092: <p>If the <span>origin</span> of <var title="">scriptURL</var> is
2093: not the <span title="same origin">same</span> as the origin of the
1.309 ihickson 2094: <span>entry script</span>, then throw a <code>SecurityError</code>
1.182 ihickson 2095: exception.</p>
1.167 ihickson 2096:
2097: <p class="note">Thus, scripts must be external files with the same
1.269 ihickson 2098: scheme as the original page: you can't load a script from a <span title="data protocol"><code title="">data:</code> URL</span> or
1.313 ihickson 2099: <span title="javascript protocol"><code title="">javascript:</code> URL</span>, and an <code>http:</code>
1.269 ihickson 2100: page couldn't start workers using scripts with <code>http:</code>
2101: URLs.</p>
1.167 ihickson 2102:
2103: </li>
1.9 ihickson 2104:
2105: <li>
2106:
1.123 ihickson 2107: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant
1.192 ihickson 2108: <code>Document</code> objects to add</a> given the <span title="script's global object">global object</span> of the <span title="concept-script">script</span> that invoked the
1.123 ihickson 2109: constructor.</p>
2110:
2111: </li>
2112:
2113: <li>
2114:
1.50 ihickson 2115: <p>Execute the following substeps atomically:</p>
1.9 ihickson 2116:
1.155 ihickson 2117: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will
1.115 ihickson 2118: shortly be associated with a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
2119: object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
1.81 ihickson 2120:
1.301 ihickson 2121: <li><p><span>Create a new <code><a href="#messageport">MessagePort</a></code> object</span>
1.192 ihickson 2122: owned by the <span title="script's global object">global
2123: object</span> of the script that invoked the method. Let this be
1.123 ihickson 2124: the <var title="">outside port</var>.</li>
1.81 ihickson 2125:
1.115 ihickson 2126: <li><p>Assign <var title="">outside port</var> to the <code title="dom-SharedWorker-port"><a href="#dom-sharedworker-port">port</a></code> attribute of <var title="">worker</var>.</li>
1.81 ihickson 2127:
1.164 ihickson 2128: <li><p>Let <var title="">worker global scope</var> be
2129: null.</li>
2130:
1.312 ihickson 2131: <li>
2132:
2133: <p>If <var title="">name</var> is not the empty string and there
2134: exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is
2135: false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is
2136: exactly equal to <var title="">name</var>, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
2137: represents an <span>absolute URL</span> with the <span>same
2138: origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
2139: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</p>
2140:
2141: <p>Otherwise, if <var title="">name</var> is the empty string
2142: and there exists a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object
2143: whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
2144: flag is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is the
2145: empty string, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute
2146: represents an <span>absolute URL</span> that is exactly equal to
2147: <var title="">scriptURL</var>, then let <var title="">worker
2148: global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
2149: object.</p>
2150:
2151: </li>
2152:
2153: <li>
2154:
2155: <p>If <var title="">worker global scope</var> is not null, but
2156: the user agent has been configured to disallow communication
2157: between the <span title="concept-script">script</span> that
2158: invoked the constructor and the worker represented by the <var title="">worker global scope</var>, then set <var title="">worker global scope</var> to null.</p>
2159:
2160: <p class="note">For example, a user agent could have a
2161: development mode that isolates a particular <span>top-level
2162: browsing context</span> from all other pages, and scripts in
2163: that development mode could be blocked from connecting to shared
2164: workers running in the normal browser mode.</p>
2165:
2166: </li>
1.164 ihickson 2167:
1.9 ihickson 2168: <li>
2169:
1.164 ihickson 2170: <p>If <var title="">worker global scope</var> is not null, then
2171: run these steps:</p>
1.81 ihickson 2172:
1.164 ihickson 2173: <ol><li><p>If <var title="">worker global scope</var>'s <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code>
1.81 ihickson 2174: attribute represents an <span>absolute URL</span> that is not
1.159 ihickson 2175: exactly equal to <var title="">scriptURL</var>, then throw a
1.309 ihickson 2176: <code>URLMismatchError</code> exception and abort all these
1.159 ihickson 2177: steps.</li>
1.81 ihickson 2178:
2179: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
2180:
1.301 ihickson 2181: <li><p><span>Create a new <code><a href="#messageport">MessagePort</a></code>
1.185 ihickson 2182: object</span> owned by <var title="">worker global
2183: scope</var>. Let this be the <var title="">inside
2184: port</var>.</li>
1.81 ihickson 2185:
2186: <li><p><span>Entangle</span> <var title="">outside port</var>
2187: and <var title="">inside port</var>.</li>
2188:
2189: <li><p>Return <var title="">worker</var> and perform the next
2190: step asynchronously.</li>
1.9 ihickson 2191:
1.81 ihickson 2192: <li><p>Create an event that uses the <code>MessageEvent</code>
1.115 ihickson 2193: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is
1.118 ihickson 2194: not cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value
1.330 ihickson 2195: is initialized to the empty string, has a <code title="dom-MessageEvent-ports">ports</code> attribute whose
1.307 ihickson 2196: value is initialized to a <span title="dfn-read-only-array">read only</span> array containing
1.330 ihickson 2197: only the newly created port, and has a <code title="dom-MessageEvent-source">source</code> attribute whose
2198: value is initialized to the newly created port, and <span>queue
2199: a task</span> to dispatch the event at <var title="">worker
2200: global scope</var>.</li>
1.43 ihickson 2201:
1.123 ihickson 2202: <li>
2203:
2204: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
2205: <var title="">worker global scope</var>'s list of <span>the
2206: worker's <code>Document</code>s</span></a> the
2207: <code>Document</code> objects in <var title="">docs</var>.</p>
2208:
2209: </li>
2210:
1.124 ihickson 2211: <li>
2212:
1.192 ihickson 2213: <p>If the <span title="script's global object">global
2214: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 2215: that invoked the constructor is a
2216: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to the list of <a href="#the-worker-s-workers">the
2217: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 2218: object that is the <span title="script's global object">global
2219: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 2220: that invoked the constructor.</p>
2221:
2222: </li>
2223:
1.81 ihickson 2224: <li><p>Abort all these steps.</li>
1.9 ihickson 2225:
1.155 ihickson 2226: </ol></li>
1.9 ihickson 2227:
1.185 ihickson 2228: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
2229: object. Let <var title="">worker global scope</var> be this new
2230: object.</li>
1.9 ihickson 2231:
1.81 ihickson 2232: <li><p>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</li>
1.9 ihickson 2233:
1.115 ihickson 2234: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of
1.81 ihickson 2235: <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 2236:
1.301 ihickson 2237: <li><p><span>Create a new <code><a href="#messageport">MessagePort</a></code> object</span>
1.81 ihickson 2238: owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 2239:
1.81 ihickson 2240: <li><p><span>Entangle</span> <var title="">outside port</var> and
2241: <var title="">inside port</var>.</li>
1.9 ihickson 2242:
1.155 ihickson 2243: </ol></li>
1.28 ihickson 2244:
1.123 ihickson 2245: <li><p>Return <var title="">worker</var> and perform the remaining
2246: steps asynchronously.</li>
1.18 ihickson 2247:
1.81 ihickson 2248: <li><p>Create an event that uses the <code>MessageEvent</code>
1.118 ihickson 2249: interface, with the name <code title="event-connect">connect</code>, which does not bubble, is not
1.115 ihickson 2250: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code> attribute whose value is
1.330 ihickson 2251: initialized to the empty string, has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value
1.307 ihickson 2252: is initialized to a <span title="dfn-read-only-array">read
1.330 ihickson 2253: only</span> array containing only the newly created port, and has a
2254: <code title="dom-MessageEvent-source">source</code> attribute whose
2255: value is initialized to the newly created port, and <span>queue a
2256: task</span> to dispatch the event at <var title="">worker global
2257: scope</var>.</li>
1.26 ihickson 2258:
2259: <li>
1.46 ihickson 2260:
1.123 ihickson 2261: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to
2262: <var title="">worker global scope</var>'s list of <span>the
2263: worker's <code>Document</code>s</span></a> the
2264: <code>Document</code> objects in <var title="">docs</var>.</p>
2265:
2266: </li>
2267:
2268: <li>
2269:
1.192 ihickson 2270: <p>If the <span title="script's global object">global object</span>
1.124 ihickson 2271: of the <span title="concept-script">script</span> that invoked the
2272: constructor is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to the list of <a href="#the-worker-s-workers">the
2273: worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1.192 ihickson 2274: object that is the <span title="script's global object">global
2275: object</span> of the <span title="concept-script">script</span>
1.124 ihickson 2276: that invoked the constructor.</p>
2277:
2278: </li>
2279:
2280: <li>
2281:
1.159 ihickson 2282: <p><a href="#run-a-worker">Run a worker</a> for <var title="">scriptURL</var>,
1.193 ihickson 2283: with the <span>script's browsing context</span> of the script that
1.159 ihickson 2284: invoked the method as the <var title="">owner browsing
1.232 ihickson 2285: context</var>, with the <span>script's document</span> of the
2286: script that invoked the method as the <var title="">owner
2287: document</var>, with the <span>origin</span> of the <span>entry
1.176 ihickson 2288: script</span> as the <var title="">owner origin</var>, and with
2289: <var title="">worker global scope</var> as the global scope.</p>
1.26 ihickson 2290:
1.60 ihickson 2291: </li>
1.81 ihickson 2292:
1.155 ihickson 2293: </ol><p>This constructor must be visible when the <span>script's global
1.192 ihickson 2294: object</span> is either a <code>Window</code> object or an object
1.327 ihickson 2295: implementing the <code><a href="#workerutils">WorkerUtils</a></code> interface.</p>
2296:
2297: <p>The <span>task source</span> for the tasks mentioned above is the
2298: <span>DOM manipulation task source</span>.</p>
2299:
2300:
2301:
2302: <h2 id="apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</h2>
2303:
2304: <pre class="idl">[NoInterfaceObject]
1.150 ihickson 2305: interface <dfn id="workerutils">WorkerUtils</dfn> {
1.306 ihickson 2306: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(DOMString... urls);
1.210 ihickson 2307: readonly attribute <a href="#workernavigator">WorkerNavigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 2308: };
1.290 ihickson 2309: <a href="#workerutils">WorkerUtils</a> implements <span>WindowTimers</span>;
1.327 ihickson 2310: <a href="#workerutils">WorkerUtils</a> implements <span>WindowBase64</span>;</pre>
2311:
2312:
2313: <p>The <code>WindowTimers</code> and <code>WindowBase64</code>
2314: interfaces are defined in the HTML specification. <a href="#refsHTML">[HTML]</a></p>
2315:
2316:
2317: <p>The DOM APIs (<code>Node</code> objects, <code>Document</code>
1.81 ihickson 2318: objects, etc) are not available to workers in this version of this
1.327 ihickson 2319: specification.</p>
2320:
2321:
2322: <h3 id="importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</h3>
2323:
2324: <p>When a script invokes the <dfn id="dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts"><code>importScripts(<var title="">urls</var>)</code></dfn> method on a
1.115 ihickson 2325: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the
1.327 ihickson 2326: following steps:</p>
2327:
2328: <ol><li><p>If there are no arguments, return without doing
1.81 ihickson 2329: anything. Abort these steps.</li>
2330:
2331: <li><p><span title="resolve a url">Resolve</span> each
2332: argument.</li>
2333:
1.309 ihickson 2334: <li><p>If any fail, throw a <code>SyntaxError</code>
1.81 ihickson 2335: exception.</li>
2336:
1.26 ihickson 2337:
1.318 ihickson 2338:
1.26 ihickson 2339: <li>
1.81 ihickson 2340:
1.45 ihickson 2341: <p>Attempt to <span>fetch</span> each resource identified by the
1.194 ihickson 2342: resulting <span title="absolute URL">absolute URLs</span>, from
1.256 ihickson 2343: the <span>entry script</span>'s <span>origin</span>, with the
1.281 ihickson 2344: <i>synchronous flag</i> set.</p>
1.318 ihickson 2345:
1.81 ihickson 2346: </li>
1.26 ihickson 2347:
2348: <li>
2349:
1.81 ihickson 2350: <p>For each argument in turn, in the order given, starting with
2351: the first one, run these substeps:</p>
1.26 ihickson 2352:
1.155 ihickson 2353: <ol><li>
1.26 ihickson 2354:
1.81 ihickson 2355: <p>Wait for the fetching attempt for the corresponding resource
2356: to complete.</p>
1.60 ihickson 2357:
1.81 ihickson 2358: <p>If the fetching attempt failed, throw a
1.309 ihickson 2359: <code>NetworkError</code> exception and abort all these
1.81 ihickson 2360: steps.</p>
1.45 ihickson 2361:
1.264 ihickson 2362: <p>If the attempt succeeds, then let <var title="">source</var> be
2363: the script resource <span>decoded as UTF-8, with error
2364: handling</span>.
2365:
2366: <a href="#refsHTML">[HTML]</a>
2367:
2368: </p>
1.85 ihickson 2369:
2370: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 2371:
1.115 ihickson 2372: <p class="note">As with the worker's script, the script here is
1.81 ihickson 2373: always assumed to be JavaScript, regardless of the MIME
1.170 ihickson 2374: type.</p>
1.61 ihickson 2375:
1.81 ihickson 2376: </li>
1.26 ihickson 2377:
1.81 ihickson 2378: <li>
1.26 ihickson 2379:
1.314 ihickson 2380: <p><span>Create a script</span>, using <var title="">source</var> as the script source, the <span>URL</span>
2381: from which <var title="">source</var> was obtained, and <var title="">language</var> as the scripting language, using the
1.189 ihickson 2382: same global object, browsing context, URL character encoding,
2383: base URL, and script group as the <span title="concept-script">script</span> that was created by the
1.115 ihickson 2384: worker's <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.81 ihickson 2385:
1.115 ihickson 2386: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.81 ihickson 2387: returns, fails to parse, fails to catch an exception, or gets
1.115 ihickson 2388: prematurely aborted by the "<a href="#kill-a-worker">kill a worker</a>" or
2389: "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined above.</p>
1.26 ihickson 2390:
1.199 ihickson 2391: <p>If it failed to parse, then throw an ECMAScript
2392: <code>SyntaxError</code> exception and abort all these
2393: steps. <a href="#refsECMA262">[ECMA262]</a></p>
1.63 ihickson 2394:
1.320 ihickson 2395: <p>If an exception was thrown or if the script was prematurely
1.81 ihickson 2396: aborted, then abort all these steps, letting the exception or
2397: aborting continue to be processed by the script that called the
1.115 ihickson 2398: <code title="dom-WorkerGlobalScope-importScripts"><a href="#dom-workerglobalscope-importscripts">importScripts()</a></code>
1.81 ihickson 2399: method.</p>
2400:
1.115 ihickson 2401: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a
1.81 ihickson 2402: worker</a>" algorithms abort the script then abort all these
2403: steps.</p>
2404:
2405: </li>
2406:
1.155 ihickson 2407: </ol></li>
1.152 ihickson 2408:
1.327 ihickson 2409: </ol><h3 id="the-workernavigator-object"><span class="secno">5.2 </span>The <code><a href="#workernavigator">WorkerNavigator</a></code> object</h3>
2410:
2411: <p>The <dfn id="dom-worker-navigator" title="dom-worker-navigator"><code>navigator</code></dfn> attribute
1.115 ihickson 2412: of the <code><a href="#workerutils">WorkerUtils</a></code> interface must return an instance of
1.210 ihickson 2413: the <code><a href="#workernavigator">WorkerNavigator</a></code> interface, which represents the
1.327 ihickson 2414: identity and state of the user agent (the client):</p>
2415:
2416: <pre class="idl">interface <dfn id="workernavigator">WorkerNavigator</dfn> {};
1.210 ihickson 2417: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorID</span>;
1.327 ihickson 2418: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorOnLine</span>;</pre>
2419:
2420: <p>Objects implementing the <code><a href="#workernavigator">WorkerNavigator</a></code> interface
1.210 ihickson 2421: also implement the <code>NavigatorID</code> and
2422: <code>NavigatorOnLine</code> interfaces.
1.205 ihickson 2423:
1.226 ihickson 2424: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2425:
1.327 ihickson 2426: </p>
2427:
1.210 ihickson 2428: <p>This <code><a href="#workernavigator">WorkerNavigator</a></code> interface must not exist if the
2429: interface's <span>relevant namespace object</span> is a
1.327 ihickson 2430: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a></p>
2431:
2432:
2433:
2434:
2435: <h3 id="interface-objects-and-constructors"><span class="secno">5.3 </span>Interface objects and constructors</h3>
2436:
2437: <p>There must be no interface objects and constructors available in
1.192 ihickson 2438: the global scope of scripts whose <span>script's global
2439: object</span> is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object except for
1.327 ihickson 2440: the following:</p>
2441:
2442: <ul><li><p><code>XMLHttpRequest</code> and all interface objects and
1.81 ihickson 2443: constructors defined by the XMLHttpRequest specifications, except
2444: that the <span>document response entity body</span> must always be
1.160 ihickson 2445: null. The <span><code>XMLHttpRequest</code> base URL</span> is the
2446: <span>script's base URL</span>; the
2447: <span><code>XMLHttpRequest</code> origin</span> is the script's
2448: <span>origin</span>. <a href="#refsXHR">[XHR]</a></li>
1.81 ihickson 2449:
1.205 ihickson 2450: <li><p>The interface objects and constructors defined by this
2451: specification.</li>
1.119 ihickson 2452:
1.205 ihickson 2453: <li><p>Constructors defined by specifications that explicitly say
2454: that they should be visible when the <span>script's global
2455: object</span> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>, a
2456: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>, or an object implementing the
2457: <code><a href="#workerutils">WorkerUtils</a></code> interface; the interfaces of any objects
2458: with such constructors; and the interfaces of any objects made
2459: accessible through APIs exposed by those constructors or made
2460: accessible through interfaces to be implemented by any objects that
2461: are themselves accessible to scripts whose <span>script's global
2462: object</span> implements the <code><a href="#workerutils">WorkerUtils</a></code>
2463: interface.</li>
2464:
2465: </ul><p class="note">These requirements do not override the requirements
2466: defined by the Web IDL specification, in particular concerning the
1.327 ihickson 2467: visibility of interfaces annotated with the <code title="">[NoInterfaceObject]</code> extended attribute.</p>
2468:
2469:
2470: <h3 id="worker-locations"><span class="secno">5.4 </span>Worker locations</h3>
2471:
2472: <pre class="idl">interface <dfn id="workerlocation">WorkerLocation</dfn> {
1.263 ihickson 2473: // <span>URL decomposition IDL attributes</span>
1.294 ihickson 2474: stringifier readonly attribute DOMString <a href="#dom-workerlocation-href" title="dom-WorkerLocation-href">href</a>;
1.115 ihickson 2475: readonly attribute DOMString <a href="#dom-workerlocation-protocol" title="dom-WorkerLocation-protocol">protocol</a>;
2476: readonly attribute DOMString <a href="#dom-workerlocation-host" title="dom-WorkerLocation-host">host</a>;
2477: readonly attribute DOMString <a href="#dom-workerlocation-hostname" title="dom-WorkerLocation-hostname">hostname</a>;
2478: readonly attribute DOMString <a href="#dom-workerlocation-port" title="dom-WorkerLocation-port">port</a>;
2479: readonly attribute DOMString <a href="#dom-workerlocation-pathname" title="dom-WorkerLocation-pathname">pathname</a>;
2480: readonly attribute DOMString <a href="#dom-workerlocation-search" title="dom-WorkerLocation-search">search</a>;
2481: readonly attribute DOMString <a href="#dom-workerlocation-hash" title="dom-WorkerLocation-hash">hash</a>;
1.327 ihickson 2482: };</pre>
2483:
2484: <p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute
2485: URL</span> set at its creation.</p>
2486:
2487: <p>The <dfn id="dom-workerlocation-href" title="dom-WorkerLocation-href"><code>href</code></dfn>
1.81 ihickson 2488: attribute must return the <span>absolute URL</span> that the object
1.327 ihickson 2489: represents.</p>
2490:
2491: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface also has the complement
1.163 ihickson 2492: of <span>URL decomposition IDL attributes</span>, <dfn id="dom-workerlocation-protocol" title="dom-WorkerLocation-protocol"><code>protocol</code></dfn>,
1.115 ihickson 2493: <dfn id="dom-workerlocation-host" title="dom-WorkerLocation-host"><code>host</code></dfn>, <dfn id="dom-workerlocation-port" title="dom-WorkerLocation-port"><code>port</code></dfn>, <dfn id="dom-workerlocation-hostname" title="dom-WorkerLocation-hostname"><code>hostname</code></dfn>,
2494: <dfn id="dom-workerlocation-pathname" title="dom-WorkerLocation-pathname"><code>pathname</code></dfn>,
2495: <dfn id="dom-workerlocation-search" title="dom-WorkerLocation-search"><code>search</code></dfn>,
1.263 ihickson 2496: and <dfn id="dom-workerlocation-hash" title="dom-WorkerLocation-hash"><code>hash</code></dfn>.
2497: These must follow the rules given for <span>URL decomposition IDL
2498: attributes</span>, with the <span title="concept-uda-input">input</span> being the <span>absolute
2499: URL</span> that the object represents (same as the <code title="dom-WorkerLocation-href"><a href="#dom-workerlocation-href">href</a></code> attribute), and the
2500: <span title="concept-uda-setter">common setter action</span> being a
2501: no-op, since the attributes are defined to be readonly.
1.205 ihickson 2502:
1.226 ihickson 2503: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 2504:
1.327 ihickson 2505: </p>
2506:
1.209 ihickson 2507: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface must not exist if the
2508: interface's <span>relevant namespace object</span> is a
1.327 ihickson 2509: <code>Window</code> object. <a href="#refsWEBIDL">[WEBIDL]</a></p>
2510:
2511:
2512:
2513:
2514:
2515:
2516: <h2 class="no-num" id="references">References</h2>
2517:
2518: <p>All references are normative unless marked "Non-normative".</p>
2519:
2520:
2521:
2522: <dl><dt id="refsDOMCORE">[DOMCORE]</dt>
1.276 ihickson 2523: <dd><cite><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html">Web DOM Core</a></cite>, A. van Kesteren. W3C.</dd>
1.153 ihickson 2524:
1.152 ihickson 2525: <dt id="refsECMA262">[ECMA262]</dt>
2526: <dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript
1.226 ihickson 2527: Language Specification</a></cite>. ECMA.</dd>
1.152 ihickson 2528:
1.226 ihickson 2529: <dt id="refsHTML">[HTML]</dt>
2530: <dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML</a></cite>,
2531: I. Hickson. WHATWG.</dd>
1.152 ihickson 2532:
1.315 ihickson 2533:
1.154 ihickson 2534: <dt id="refsRFC2119">[RFC2119]</dt>
1.265 ihickson 2535: <dd><cite><a href="http://tools.ietf.org/html/rfc2119">Key words for use in
1.226 ihickson 2536: RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF.</dd>
1.154 ihickson 2537:
2538: <dt id="refsWEBIDL">[WEBIDL]</dt>
1.318 ihickson 2539:
2540: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
1.226 ihickson 2541: IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2542:
1.152 ihickson 2543: <dt id="refsXHR">[XHR]</dt>
1.318 ihickson 2544:
2545: <dd><cite><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/"><code>XMLHttpRequest</code></a></cite>,
1.226 ihickson 2546: A. van Kesteren. W3C.</dd>
1.152 ihickson 2547:
1.327 ihickson 2548: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2> <!-- ACKS -->
2549:
2550: <p>Thanks to
1.81 ihickson 2551:
2552: Aaron Boodman,
1.155 ihickson 2553: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2554: Anne van Kesteren,
2555: Ben Turner,
2556: Dmitry Titov,
1.96 ihickson 2557: Drew Wilson,
1.97 ihickson 2558: Jeremy Orlow,
1.81 ihickson 2559: Jonas Sicking,
2560: Justin James,
2561: Kevin Hakanson,
2562: Maciej Stachowiak,
2563: Michael Nordman,
2564: Mike Smith,
2565:
2566: and
2567:
2568: Philip Taylor
2569:
1.327 ihickson 2570: for their useful and substantial comments.</p>
2571:
2572: <p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2573: technology and whose experience has been a huge influence on this
1.327 ihickson 2574: specification.</p>
2575:
2576:
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