Annotation of html5/workers/Overview.html, revision 1.417
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:
1.388 ihickson 195: </style><link rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-ED" 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">
1.388 ihickson 215: <p><a href="http://www.w3.org/"><img width="72" src="http://www.w3.org/Icons/w3c_home" alt="W3C" height="48"></a></p>
1.271 ihickson 216:
1.54 ihickson 217: <h1>Web Workers</h1>
1.281 ihickson 218:
1.417 ! ihickson 219: <h2 class="no-num no-toc" id="editor-s-draft-28-april-2014">Editor's Draft 28 April 2014</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>
1.388 ihickson 223: <dd><a href="http://dev.w3.org/html5/workers/" class="latest-link">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:
1.345 ihickson 278: <p>If you wish to make comments regarding this document, you can
1.327 ihickson 279: enter feedback using this form:</p>
280:
281: <form action="http://www.whatwg.org/specs/web-apps/current-work/file-spam.cgi" method="post">
1.271 ihickson 282: <fieldset><legend>Feedback Comments</legend>
1.388 ihickson 283: <input value="top" name="id" type="hidden"><input value="Web Workers (editor: Ian Hickson)" name="component" type="hidden"><input value="html" name="response" type="hidden"><p><label for="feedbackBox">Please enter your feedback, carefully
1.271 ihickson 284: indicating the title of the section for which you are submitting
285: feedback, quoting the text that's wrong today if appropriate. If
286: you're suggesting a new feature, it's really important to say
287: <em>what</em> the problem you're trying to solve is. That's more
288: important than the solution, in fact.</label></p>
1.388 ihickson 289: <p><textarea name="text" rows="10" id="feedbackBox" cols="79"></textarea></p>
1.271 ihickson 290: <p class="note">Please don't use section numbers as these tend to
291: change rapidly and make your feedback harder to understand.</p>
292: <script type="text/javascript">
1.287 ihickson 293: function checkFeedbackForm(form) {
294: if (form.elements.text.value.match(/^ *</)) {
295: alert('Please don\'t start your feedback with an angle bracket, instead explain what topic your feedback is about first.');
296: return true;
297: } else if (form.elements.text.value.match(/ [^ ]+ [^ ]+ [^ ]+ [^ ]+ /)) {
298: if (form.elements.text.value.match(/^Please enter your feedback, carefully/)) {
299: alert('Please enter your feedback, explaining what is wrong, and without repeating the instructions. Thanks!');
300: return true;
301: } else if (form.elements.text.value.match(/ [^ ]+ [^ ]+ [^ ]+ [^ ]+ /)) {
302: form.action = "http://www.whatwg.org/specs/web-apps/current-work/file-bug.cgi";
303: return true;
304: } else {
305: alert('Please include significantly more detail about exactly what problem you are trying to solve.');
306: return false;
307: }
308: }
309: }
1.271 ihickson 310: </script><p>
1.388 ihickson 311: <input value="Submit feedback" onclick="return checkFeedbackForm(form)" type="submit"><small>(Note: Your IP address and user agent will be publicly recorded for spam prevention purposes.)</small>
1.271 ihickson 312: </p>
1.327 ihickson 313: </fieldset></form>
314:
315:
316: <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 317: <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>),
1.115 ihickson 318: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
319: <a href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
1.327 ihickson 320: All feedback is welcome.</p>
321:
322:
323: <p>Implementors should be aware that this specification is not
1.81 ihickson 324: stable. <strong>Implementors who are not taking part in the
325: discussions are likely to find the specification changing out from
326: under them in incompatible ways.</strong> Vendors interested in
327: implementing this specification before it eventually reaches the
328: Candidate Recommendation stage should join the aforementioned
1.327 ihickson 329: mailing lists and take part in the discussions.</p>
330:
331: <div id="multipage-common">
332: </div>
333:
334: <p>The latest
1.271 ihickson 335: stable version of the editor's draft of this specification is always
336: available on <a href="http://dev.w3.org/html5/workers/">the W3C CVS server</a>
337: and in the <a href="http://svn.whatwg.org/webapps/">WHATWG
338: Subversion repository</a>. The <a href="http://www.whatwg.org/specs/web-apps/current-work/complete.html">latest
339: editor's working copy</a> (which may contain unfinished text in the
340: process of being prepared) contains the latest draft text of this
341: 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 342: FAQ</a>.</p>
343:
344: <p>Notifications of changes to this specification are sent along
1.271 ihickson 345: with notifications of changes to related specifications using the
1.327 ihickson 346: following mechanisms:</p>
347: <dl><dt>E-mail notifications of changes</dt>
1.271 ihickson 348: <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>
349: <dt>Browsable version-control record of all changes:</dt>
350: <dd>CVSWeb interface with side-by-side diffs: <a href="http://dev.w3.org/cvsweb/html5/">http://dev.w3.org/cvsweb/html5/</a></dd>
351: <dd>Annotated summary with unified diffs: <a href="http://html5.org/tools/web-apps-tracker">http://html5.org/tools/web-apps-tracker</a></dd>
352: <dd>Raw Subversion interface: <code>svn checkout http://svn.whatwg.org/webapps/</code></dd>
353: </dl><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Applications
1.81 ihickson 354: Working Group</a> is the W3C working group responsible for this
355: specification's progress along the W3C Recommendation track.
1.417 ! ihickson 356: This specification is the 28 April 2014 Editor's Draft.
1.327 ihickson 357: </p>
358:
359:
360:
361: <p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5
1.388 ihickson 362: February 2004 W3C Patent Policy</a>. W3C maintains a <a rel="disclosure" href="http://www.w3.org/2004/01/pp-impl/42538/status">public list of
1.81 ihickson 363: any patent disclosures</a> made in connection with the deliverables
364: of the group; that page also includes instructions for disclosing a
365: patent. An individual who has actual knowledge of a patent which the
1.115 ihickson 366: individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
367: 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 368: 6 of the W3C Patent Policy</a>.</p>
369:
370:
371: <h2 class="no-num no-toc" id="contents">Table of Contents</h2>
372:
1.318 ihickson 373:
1.115 ihickson 374: <ol class="toc">
375: <li><a href="#introduction"><span class="secno">1 </span>Introduction</a>
1.81 ihickson 376: <ol>
1.115 ihickson 377: <li><a href="#scope"><span class="secno">1.1 </span>Scope</a></li>
1.303 ihickson 378: <li><a href="#examples"><span class="secno">1.2 </span>Examples</a>
1.81 ihickson 379: <ol>
1.115 ihickson 380: <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 381: <li><a href="#worker-used-for-background-i-o"><span class="secno">1.2.2 </span>Worker used for background I/O</a></li>
382: <li><a href="#shared-workers-introduction"><span class="secno">1.2.3 </span>Shared workers introduction</a></li>
383: <li><a href="#shared-state-using-a-shared-worker"><span class="secno">1.2.4 </span>Shared state using a shared worker</a></li>
384: <li><a href="#delegation"><span class="secno">1.2.5 </span>Delegation</a></ol></li>
1.303 ihickson 385: <li><a href="#tutorials"><span class="secno">1.3 </span>Tutorials</a>
386: <ol>
387: <li><a href="#creating-a-dedicated-worker"><span class="secno">1.3.1 </span>Creating a dedicated worker</a></li>
388: <li><a href="#communicating-with-a-dedicated-worker"><span class="secno">1.3.2 </span>Communicating with a dedicated worker</a></li>
389: <li><a href="#shared-workers"><span class="secno">1.3.3 </span>Shared workers</a></ol></ol></li>
1.148 ihickson 390: <li><a href="#conformance-requirements"><span class="secno">2 </span>Conformance requirements</a>
1.82 ihickson 391: <ol>
1.148 ihickson 392: <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></ol></li>
393: <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
394: <li><a href="#infrastructure"><span class="secno">4 </span>Infrastructure</a>
395: <ol>
1.397 ihickson 396: <li><a href="#the-global-scope"><span class="secno">4.1 </span>The global scope</a>
1.81 ihickson 397: <ol>
1.397 ihickson 398: <li><a href="#the-workerglobalscope-common-interface"><span class="secno">4.1.1 </span>The <code>WorkerGlobalScope</code> common interface</a></li>
399: <li><a href="#dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.1.2 </span>Dedicated workers and the <code>DedicatedWorkerGlobalScope</code> interface</a></li>
400: <li><a href="#shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> interface</a></ol></li>
1.409 ihickson 401: <li><a href="#worker-event-loop"><span class="secno">4.2 </span>The event loop</a></li>
1.397 ihickson 402: <li><a href="#the-worker-s-lifetime"><span class="secno">4.3 </span>The worker's lifetime</a></li>
403: <li><a href="#processing-model"><span class="secno">4.4 </span>Processing model</a></li>
404: <li><a href="#runtime-script-errors"><span class="secno">4.5 </span>Runtime script errors</a></li>
405: <li><a href="#creating-workers"><span class="secno">4.6 </span>Creating workers</a>
1.81 ihickson 406: <ol>
1.397 ihickson 407: <li><a href="#the-abstractworker-abstract-interface"><span class="secno">4.6.1 </span>The <code>AbstractWorker</code> abstract interface</a></li>
1.398 ihickson 408: <li><a href="#script-settings-for-workers"><span class="secno">4.6.2 </span>Script settings for workers</a></li>
409: <li><a href="#dedicated-workers-and-the-worker-interface"><span class="secno">4.6.3 </span>Dedicated workers and the <code>Worker</code> interface</a></li>
410: <li><a href="#shared-workers-and-the-sharedworker-interface"><span class="secno">4.6.4 </span>Shared workers and the <code>SharedWorker</code> interface</a></ol></ol></li>
1.148 ihickson 411: <li><a href="#apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</a>
1.81 ihickson 412: <ol>
1.148 ihickson 413: <li><a href="#importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</a></li>
1.210 ihickson 414: <li><a href="#the-workernavigator-object"><span class="secno">5.2 </span>The <code>WorkerNavigator</code> object</a></li>
1.412 ihickson 415: <li><a href="#worker-locations"><span class="secno">5.3 </span>Worker locations</a></ol></li>
1.388 ihickson 416: <li><a href="#references" class="no-num">References</a></li>
417: <li><a href="#acknowledgements" class="no-num">Acknowledgements</a></ol>
1.327 ihickson 418:
419: <hr><h2 id="introduction"><span class="secno">1 </span>Introduction</h2>
420:
421: <h3 id="scope"><span class="secno">1.1 </span>Scope</h3>
422:
423: <p><i>This section is non-normative.</i></p>
424:
1.396 ihickson 425: <p>This specification defines an API for running scripts in the background independently of any
426: user interface scripts.</p>
1.327 ihickson 427:
1.396 ihickson 428: <p>This allows for long-running scripts that are not interrupted by scripts that respond to clicks
429: or other user interactions, and allows long tasks to be executed without yielding to keep the page
1.327 ihickson 430: responsive.</p>
431:
1.396 ihickson 432: <p>Workers (as these background scripts are called herein) are relatively heavy-weight, and are
433: not intended to be used in large numbers. For example, it would be inappropriate to launch one
434: worker for each pixel of a four megapixel image. The examples below show some appropriate uses of
435: workers.</p>
1.327 ihickson 436:
1.396 ihickson 437: <p>Generally, workers are expected to be long-lived, have a high start-up performance cost, and a
438: high per-instance memory cost.</p>
1.327 ihickson 439:
440:
441: <h3 id="examples"><span class="secno">1.2 </span>Examples</h3>
442:
443: <p><i>This section is non-normative.</i></p>
444:
1.396 ihickson 445: <p>There are a variety of uses that workers can be put to. The following subsections show various
446: examples of this use.</p>
1.327 ihickson 447:
448: <h4 id="a-background-number-crunching-worker"><span class="secno">1.2.1 </span>A background number-crunching worker</h4>
449:
450: <p><i>This section is non-normative.</i></p>
451:
452: <p>The simplest use of workers is for performing a computationally
453: expensive task without interrupting the user interface.</p>
454:
1.396 ihickson 455: <p>In this example, the main document spawns a worker to (naïvely) compute prime numbers, and
456: progressively displays the most recently found prime number.</p>
1.327 ihickson 457:
458: <p>The main page is as follows:</p>
459:
460: <pre><!DOCTYPE HTML>
1.81 ihickson 461: <html>
462: <head>
463: <title>Worker example: One-core computation</title>
464: </head>
465: <body>
466: <p>The highest prime number discovered so far is: <output id="result"></output></p>
467: <script>
1.50 ihickson 468: var worker = new Worker('worker.js');
469: worker.onmessage = function (event) {
1.54 ihickson 470: document.getElementById('result').textContent = event.data;
1.29 ihickson 471: };
1.81 ihickson 472: </script>
473: </body>
1.327 ihickson 474: </html></pre>
475:
1.396 ihickson 476: <p>The <code title="dom-Worker"><a href="#dom-worker">Worker()</a></code> constructor call creates a worker and returns a
477: <code><a href="#worker">Worker</a></code> object representing that worker, which is used to communicate with the worker.
478: That object's <code title="handler-Worker-onmessage"><a href="#handler-worker-onmessage">onmessage</a></code> event handler allows the
479: code to receive messages from the worker.</p>
1.327 ihickson 480:
481: <p>The worker itself is as follows:</p>
482:
483: <pre>var n = 1;
1.29 ihickson 484: search: while (true) {
485: n += 1;
486: for (var i = 2; i <= Math.sqrt(n); i += 1)
487: if (n % i == 0)
488: continue search;
489: // found a prime!
1.50 ihickson 490: postMessage(n);
1.327 ihickson 491: }</pre>
492:
1.396 ihickson 493: <p>The bulk of this code is simply an unoptimized search for a prime number. The <code title="dom-DedicatedWorkerGlobalScope-postMessage"><a href="#dom-dedicatedworkerglobalscope-postmessage">postMessage()</a></code> method is used to send a
494: message back to the page when a prime is found.</p>
1.327 ihickson 495:
1.416 ihickson 496: <p><a href="//www.whatwg.org/demos/workers/primes/page.html">View this example online</a>.</p>
1.327 ihickson 497:
498:
499:
500:
501: <h4 id="worker-used-for-background-i-o"><span class="secno">1.2.2 </span>Worker used for background I/O</h4>
502:
503: <p><i>This section is non-normative.</i></p>
504:
1.351 ihickson 505: <p>In this example, the main document uses two workers, one for fetching stock updates at regular
506: intervals, and one for performing search queries that the user requests.</p>
1.327 ihickson 507:
508: <p>The main page is as follows:</p>
509:
510: <pre><!DOCTYPE HTML>
1.81 ihickson 511: <html>
512: <head>
513: <title>Worker example: Stock ticker</title>
514: <script>
1.33 ihickson 515: // TICKER
516: var symbol = 'GOOG'; // default symbol to watch
1.50 ihickson 517: var ticker = new Worker('ticker.js');
1.33 ihickson 518:
519: // SEARCHER
1.50 ihickson 520: var searcher = new Worker('searcher.js');
1.33 ihickson 521: function search(query) {
1.50 ihickson 522: searcher.postMessage(query);
1.33 ihickson 523: }
524:
525: // SYMBOL SELECTION UI
526: function select(newSymbol) {
527: symbol = newSymbol;
1.50 ihickson 528: ticker.postMessage(symbol);
1.33 ihickson 529: }
1.81 ihickson 530: </script>
531: </head>
1.122 ihickson 532: <body onload="search('')">
1.81 ihickson 533: <p><output id="symbol"></output> <output id="value"></output></p>
534: <script>
1.50 ihickson 535: ticker.onmessage = function (event) {
1.54 ihickson 536: var data = event.data.split(' ');
1.33 ihickson 537: document.getElementById('symbol').textContent = data[0];
538: document.getElementById('value').textContent = data[1];
539: };
1.50 ihickson 540: ticker.postMessage(symbol);
1.81 ihickson 541: </script>
1.122 ihickson 542: <p><label>Search: <input type="text" autofocus oninput="search(this.value)"></label></p>
1.81 ihickson 543: <ul id="results"></ul>
544: <script>
1.50 ihickson 545: searcher.onmessage = function (event) {
1.54 ihickson 546: var data = event.data.split(' ');
1.33 ihickson 547: var results = document.getElementById('results');
548: while (results.hasChildNodes()) // clear previous results
549: results.removeChild(results.firstChild);
550: for (var i = 0; i < data.length; i += 1) {
551: // add a list item with a button for each result
552: var li = document.createElement('li');
553: var button = document.createElement('button');
554: button.value = data[i];
555: button.type = 'button';
556: button.onclick = function () { select(this.value); };
557: button.textContent = data[i];
558: li.appendChild(button);
559: results.appendChild(li);
560: }
561: };
1.81 ihickson 562: </script>
563: <p>(The data in this example is not real. Try searching for "Google" or "Apple".)</p>
564: </body>
1.327 ihickson 565: </html></pre>
566:
1.351 ihickson 567: <p>The two workers use a common library for performing the actual network calls. This library is
568: as follows:</p>
1.327 ihickson 569:
570: <pre>function get(url) {
1.50 ihickson 571: try {
572: var xhr = new XMLHttpRequest();
573: xhr.open('GET', url, false);
574: xhr.send();
575: return xhr.responseText;
576: } catch (e) {
577: return ''; // turn all errors into empty results
578: }
1.327 ihickson 579: }</pre>
580:
581: <p>The stock updater worker is as follows:</p>
582:
583: <pre>importScripts('io.js');
1.33 ihickson 584: var timer;
585: var symbol;
586: function update() {
1.50 ihickson 587: postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
1.33 ihickson 588: timer = setTimeout(update, 10000);
589: }
1.50 ihickson 590: onmessage = function (event) {
1.33 ihickson 591: if (timer)
592: clearTimeout(timer);
1.54 ihickson 593: symbol = event.data;
1.33 ihickson 594: update();
1.327 ihickson 595: };</pre>
596:
597: <p>The search query worker is as follows:</p>
598:
599: <pre>importScripts('io.js');
1.50 ihickson 600: onmessage = function (event) {
1.54 ihickson 601: postMessage(get('search.cgi?' + event.data));
1.327 ihickson 602: };</pre>
603:
1.416 ihickson 604: <p><a href="//www.whatwg.org/demos/workers/stocks/page.html">View this example online</a>.</p>
1.327 ihickson 605:
606:
607: <h4 id="shared-workers-introduction"><span class="secno">1.2.3 </span>Shared workers introduction</h4>
608:
609: <p><i>This section is non-normative.</i></p>
610:
1.396 ihickson 611: <p>This section introduces shared workers using a Hello World example. Shared workers use slightly
612: different APIs, since each worker can have multiple connections.</p>
613:
614: <p>This first example shows how you connect to a worker and how a worker can send a message back
615: to the page when it connects to it. Received messages are displayed in a log.</p>
1.327 ihickson 616:
617: <p>Here is the HTML page:</p>
618:
619: <pre><!DOCTYPE HTML>
1.239 ihickson 620: <title>Shared workers: demo 1</title>
621: <pre id="log">Log:</pre>
622: <script>
623: var worker = new SharedWorker('test.js');
624: var log = document.getElementById('log');
625: worker.port.onmessage = function(e) { // note: not worker.onmessage!
626: log.textContent += '\n' + e.data;
627: }
628: </script>
1.327 ihickson 629: </pre>
630:
631: <p>Here is the JavaScript worker:</p>
632:
633: <pre>onconnect = function(e) {
1.239 ihickson 634: var port = e.ports[0];
635: port.postMessage('Hello World!');
636: }
1.327 ihickson 637: </pre>
638:
1.416 ihickson 639: <p><a href="//www.whatwg.org/demos/workers/shared/001/test.html">View this example online</a>.</p>
1.327 ihickson 640:
1.396 ihickson 641: <hr><p>This second example extends the first one by changing two things: first, messages are received
642: using <code title="">addEventListener()</code> instead of an <span title="event handler IDL
643: attributes">event handler IDL attribute</span>, and second, a message is sent <em>to</em> the
644: worker, causing the worker to send another message in return. Received messages are again
1.327 ihickson 645: displayed in a log.</p>
646:
647: <p>Here is the HTML page:</p>
648:
649: <pre><!DOCTYPE HTML>
1.240 ihickson 650: <title>Shared workers: demo 2</title>
1.239 ihickson 651: <pre id="log">Log:</pre>
652: <script>
653: var worker = new SharedWorker('test.js');
654: var log = document.getElementById('log');
1.240 ihickson 655: worker.port.addEventListener('message', function(e) {
1.239 ihickson 656: log.textContent += '\n' + e.data;
1.240 ihickson 657: }, false);
658: worker.port.start(); // note: need this when using addEventListener
659: worker.port.postMessage('ping');
1.239 ihickson 660: </script>
1.327 ihickson 661: </pre>
662:
663: <p>Here is the JavaScript worker:</p>
664:
665: <pre>onconnect = function(e) {
1.239 ihickson 666: var port = e.ports[0];
667: port.postMessage('Hello World!');
1.240 ihickson 668: port.onmessage = function(e) {
669: port.postMessage('pong'); // not e.ports[0].postMessage!
670: // e.target.postMessage('pong'); would work also
671: }
1.239 ihickson 672: }
1.327 ihickson 673: </pre>
674:
1.416 ihickson 675: <p><a href="//www.whatwg.org/demos/workers/shared/002/test.html">View this example online</a>.</p>
1.327 ihickson 676:
1.396 ihickson 677: <hr><p>Finally, the example is extended to show how two pages can connect to the same worker; in this
678: case, the second page is merely in an <code>iframe</code> on the first page, but the same
679: principle would apply to an entirely separate page in a separate <span>top-level browsing
680: context</span>.</p>
1.327 ihickson 681:
682: <p>Here is the outer HTML page:</p>
683:
684: <pre><!DOCTYPE HTML>
1.239 ihickson 685: <title>Shared workers: demo 3</title>
686: <pre id="log">Log:</pre>
687: <script>
688: var worker = new SharedWorker('test.js');
689: var log = document.getElementById('log');
690: worker.port.addEventListener('message', function(e) {
691: log.textContent += '\n' + e.data;
692: }, false);
693: worker.port.start();
694: worker.port.postMessage('ping');
695: </script>
696: <iframe src="inner.html"></iframe>
1.327 ihickson 697: </pre>
698:
699: <p>Here is the inner HTML page:</p>
700:
701: <pre><!DOCTYPE HTML>
1.239 ihickson 702: <title>Shared workers: demo 3 inner frame</title>
703: <pre id=log>Inner log:</pre>
704: <script>
705: var worker = new SharedWorker('test.js');
706: var log = document.getElementById('log');
707: worker.port.onmessage = function(e) {
708: log.textContent += '\n' + e.data;
709: }
710: </script>
1.327 ihickson 711: </pre>
712:
713: <p>Here is the JavaScript worker:</p>
714:
715: <pre>var count = 0;
1.239 ihickson 716: onconnect = function(e) {
717: count += 1;
718: var port = e.ports[0];
719: port.postMessage('Hello World! You are connection #' + count);
720: port.onmessage = function(e) {
721: port.postMessage('pong');
722: }
723: }
1.327 ihickson 724: </pre>
725:
1.416 ihickson 726: <p><a href="//www.whatwg.org/demos/workers/shared/003/test.html">View this example online</a>.</p>
1.327 ihickson 727:
728:
729: <h4 id="shared-state-using-a-shared-worker"><span class="secno">1.2.4 </span>Shared state using a shared worker</h4>
730:
731: <p><i>This section is non-normative.</i></p>
732:
1.396 ihickson 733: <p>In this example, multiple windows (viewers) can be opened that are all viewing the same map.
734: All the windows share the same map information, with a single worker coordinating all the viewers.
735: Each viewer can move around independently, but if they set any data on the map, all the viewers
736: are updated.</p>
1.327 ihickson 737:
1.396 ihickson 738: <p>The main page isn't interesting, it merely provides a way to open the viewers:</p>
1.327 ihickson 739:
740: <pre><!DOCTYPE HTML>
1.81 ihickson 741: <html>
742: <head>
743: <title>Workers example: Multiviewer</title>
744: <script>
1.36 ihickson 745: function openViewer() {
746: window.open('viewer.html');
747: }
1.81 ihickson 748: </script>
749: </head>
750: <body>
751: <p><button type=button onclick="openViewer()">Open a new
752: viewer</button></p>
753: <p>Each viewer opens in a new window. You can have as many viewers
754: as you like, they all view the same data.</p>
755: </body>
1.327 ihickson 756: </html></pre>
757:
758: <p>The viewer is more involved:</p>
759:
760: <pre><!DOCTYPE HTML>
1.81 ihickson 761: <html>
762: <head>
763: <title>Workers example: Multiviewer viewer</title>
764: <script>
1.50 ihickson 765: var worker = new SharedWorker('worker.js', 'core');
1.36 ihickson 766:
767: // CONFIGURATION
768: function configure(event) {
1.54 ihickson 769: if (event.data.substr(0, 4) != 'cfg ') return;
1.375 ihickson 770: var name = event.data.substr(4).split(' ', 1)[0];
1.36 ihickson 771: // update display to mention our name is name
772: document.getElementsByTagName('h1')[0].textContent += ' ' + name;
773: // no longer need this listener
1.43 ihickson 774: worker.port.removeEventListener('message', configure, false);
1.36 ihickson 775: }
1.53 ihickson 776: worker.port.addEventListener('message', configure, false);
1.36 ihickson 777:
778: // MAP
779: function paintMap(event) {
1.54 ihickson 780: if (event.data.substr(0, 4) != 'map ') return;
781: var data = event.data.substr(4).split(',');
1.36 ihickson 782: // display tiles data[0] .. data[8]
783: var canvas = document.getElementById('map');
784: var context = canvas.getContext('2d');
785: for (var y = 0; y < 3; y += 1) {
786: for (var x = 0; x < 3; x += 1) {
787: var tile = data[y * 3 + x];
788: if (tile == '0')
789: context.fillStyle = 'green';
790: else
791: context.fillStyle = 'maroon';
1.375 ihickson 792: context.fillRect(x * 50, y * 50, 50, 50);
1.36 ihickson 793: }
794: }
795: }
1.53 ihickson 796: worker.port.addEventListener('message', paintMap, false);
1.36 ihickson 797:
798: // PUBLIC CHAT
799: function updatePublicChat(event) {
1.54 ihickson 800: if (event.data.substr(0, 4) != 'txt ') return;
1.375 ihickson 801: var name = event.data.substr(4).split(' ', 1)[0];
802: var message = event.data.substr(4 + name.length + 1);
1.81 ihickson 803: // display "<name> message" in public chat
1.375 ihickson 804: var public = document.getElementById('public');
805: var p = document.createElement('p');
806: var n = document.createElement('button');
807: n.textContent = '<' + name + '> ';
808: n.onclick = function () { worker.port.postMessage('msg ' + name); };
809: p.appendChild(n);
810: var m = document.createElement('span');
811: m.textContent = message;
812: p.appendChild(m);
813: public.appendChild(p);
1.36 ihickson 814: }
1.53 ihickson 815: worker.port.addEventListener('message', updatePublicChat, false);
1.36 ihickson 816:
817: // PRIVATE CHAT
818: function startPrivateChat(event) {
1.54 ihickson 819: if (event.data.substr(0, 4) != 'msg ') return;
1.375 ihickson 820: var name = event.data.substr(4).split(' ', 1)[0];
1.84 ihickson 821: var port = event.ports[0];
1.36 ihickson 822: // display a private chat UI
823: var ul = document.getElementById('private');
824: var li = document.createElement('li');
825: var h3 = document.createElement('h3');
826: h3.textContent = 'Private chat with ' + name;
827: li.appendChild(h3);
1.375 ihickson 828: var div = document.createElement('div');
1.36 ihickson 829: var addMessage = function(name, message) {
1.375 ihickson 830: var p = document.createElement('p');
831: var n = document.createElement('strong');
832: n.textContent = '<' + name + '> ';
833: p.appendChild(n);
834: var t = document.createElement('span');
835: t.textContent = message;
836: p.appendChild(t);
837: div.appendChild(p);
1.36 ihickson 838: };
839: port.onmessage = function (event) {
1.54 ihickson 840: addMessage(name, event.data);
1.36 ihickson 841: };
1.375 ihickson 842: li.appendChild(div);
1.36 ihickson 843: var form = document.createElement('form');
844: var p = document.createElement('p');
845: var input = document.createElement('input');
846: input.size = 50;
847: p.appendChild(input);
848: p.appendChild(document.createTextNode(' '));
849: var button = document.createElement('button');
850: button.textContent = 'Post';
851: p.appendChild(button);
852: form.onsubmit = function () {
853: port.postMessage(input.value);
854: addMessage('me', input.value);
855: input.value = '';
856: return false;
857: };
858: form.appendChild(p);
859: li.appendChild(form);
1.375 ihickson 860: ul.appendChild(li);
1.36 ihickson 861: }
1.53 ihickson 862: worker.port.addEventListener('message', startPrivateChat, false);
1.188 ihickson 863:
864: worker.port.start();
1.81 ihickson 865: </script>
866: </head>
867: <body>
868: <h1>Viewer</h1>
869: <h2>Map</h2>
870: <p><canvas id="map" height=150 width=150></canvas></p>
871: <p>
872: <button type=button onclick="worker.port.postMessage('mov left')">Left</button>
873: <button type=button onclick="worker.port.postMessage('mov up')">Up</button>
874: <button type=button onclick="worker.port.postMessage('mov down')">Down</button>
875: <button type=button onclick="worker.port.postMessage('mov right')">Right</button>
876: <button type=button onclick="worker.port.postMessage('set 0')">Set 0</button>
877: <button type=button onclick="worker.port.postMessage('set 1')">Set 1</button>
878: </p>
879: <h2>Public Chat</h2>
1.375 ihickson 880: <div id="public"></div>
1.81 ihickson 881: <form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
882: <p>
883: <input type="text" name="message" size="50">
884: <button>Post</button>
885: </p>
886: </form>
887: <h2>Private Chat</h2>
888: <ul id="private"></ul>
889: </body>
890: </html>
1.327 ihickson 891: </pre>
892:
1.396 ihickson 893: <p>There are several key things worth noting about the way the viewer is written.</p>
894:
895: <p><strong>Multiple listeners</strong>. Instead of a single message processing function, the code
896: here attaches multiple event listeners, each one performing a quick check to see if it is relevant
897: for the message. In this example it doesn't make much difference, but if multiple authors wanted
898: to collaborate using a single port to communicate with a worker, it would allow for independent
899: code instead of changes having to all be made to a single event handling function.</p>
1.327 ihickson 900:
1.396 ihickson 901: <p>Registering event listeners in this way also allows you to unregister specific listeners when
902: you are done with them, as is done with the <code title="">configure()</code> method in this
1.327 ihickson 903: example.</p>
904:
905: <p>Finally, the worker:</p>
906:
907: <pre>
1.155 ihickson 908: var nextName = 0;
1.36 ihickson 909: function getNextName() {
910: // this could use more friendly names
911: // but for now just return a number
912: return nextName++;
913: }
914:
915: var map = [
916: [0, 0, 0, 0, 0, 0, 0],
917: [1, 1, 0, 1, 0, 1, 1],
918: [0, 1, 0, 1, 0, 0, 0],
919: [0, 1, 0, 1, 0, 1, 1],
920: [0, 0, 0, 1, 0, 0, 0],
921: [1, 0, 0, 1, 1, 1, 1],
922: [1, 1, 0, 1, 1, 0, 1],
923: ];
924:
925: function wrapX(x) {
926: if (x < 0) return wrapX(x + map[0].length);
1.81 ihickson 927: if (x >= map[0].length) return wrapX(x - map[0].length);
1.36 ihickson 928: return x;
929: }
930:
931: function wrapY(y) {
932: if (y < 0) return wrapY(y + map.length);
1.81 ihickson 933: if (y >= map[0].length) return wrapY(y - map.length);
1.36 ihickson 934: return y;
935: }
936:
1.375 ihickson 937: function wrap(val, min, max) {
938: if (val < min)
939: return val + (max-min)+1;
940: if (val > max)
941: return val - (max-min)-1;
942: return val;
943: }
944:
945: function sendMapData(viewer) {
1.36 ihickson 946: var data = '';
947: for (var y = viewer.y-1; y <= viewer.y+1; y += 1) {
948: for (var x = viewer.x-1; x <= viewer.x+1; x += 1) {
949: if (data != '')
950: data += ',';
1.375 ihickson 951: data += map[wrap(y, 0, map[0].length-1)][wrap(x, 0, map.length-1)];
1.36 ihickson 952: }
953: }
1.375 ihickson 954: viewer.port.postMessage('map ' + data);
1.36 ihickson 955: }
956:
957: var viewers = {};
958: onconnect = function (event) {
1.375 ihickson 959: var name = getNextName();
960: event.ports[0]._data = { port: event.ports[0], name: name, x: 0, y: 0, };
961: viewers[name] = event.ports[0]._data;
1.84 ihickson 962: event.ports[0].postMessage('cfg ' + name);
963: event.ports[0].onmessage = getMessage;
1.375 ihickson 964: sendMapData(event.ports[0]._data);
1.36 ihickson 965: };
966:
967: function getMessage(event) {
1.54 ihickson 968: switch (event.data.substr(0, 4)) {
1.36 ihickson 969: case 'mov ':
1.54 ihickson 970: var direction = event.data.substr(4);
1.36 ihickson 971: var dx = 0;
972: var dy = 0;
973: switch (direction) {
974: case 'up': dy = -1; break;
975: case 'down': dy = 1; break;
976: case 'left': dx = -1; break;
977: case 'right': dx = 1; break;
978: }
979: event.target._data.x = wrapX(event.target._data.x + dx);
980: event.target._data.y = wrapY(event.target._data.y + dy);
1.375 ihickson 981: sendMapData(event.target._data);
1.36 ihickson 982: break;
983: case 'set ':
1.54 ihickson 984: var value = event.data.substr(4);
1.36 ihickson 985: map[event.target._data.y][event.target._data.x] = value;
986: for (var viewer in viewers)
1.405 ihickson 987: sendMapData(viewers[viewer]);
1.36 ihickson 988: break;
989: case 'txt ':
1.375 ihickson 990: var name = event.target._data.name;
1.54 ihickson 991: var message = event.data.substr(4);
1.36 ihickson 992: for (var viewer in viewers)
993: viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
994: break;
995: case 'msg ':
1.375 ihickson 996: var party1 = event.target._data;
997: var party2 = viewers[event.data.substr(4).split(' ', 1)[0]];
1.36 ihickson 998: if (party2) {
999: var channel = new MessageChannel();
1.84 ihickson 1000: party1.port.postMessage('msg ' + party2.name, [channel.port1]);
1001: party2.port.postMessage('msg ' + party1.name, [channel.port2]);
1.36 ihickson 1002: }
1003: break;
1004: }
1.327 ihickson 1005: }</pre>
1006:
1.396 ihickson 1007: <p><strong>Connecting to multiple pages</strong>. The script uses the <code title="handler-SharedWorkerGlobalScope-onconnect"><a href="#handler-sharedworkerglobalscope-onconnect">onconnect</a></code> event listener to listen for
1008: multiple connections.</p>
1009:
1010: <p><strong>Direct channels</strong>. When the worker receives a "msg" message from one viewer
1011: naming another viewer, it sets up a direct connection between the two, so that the two viewers can
1012: communicate directly without the worker having to proxy all the messages.</p>
1.327 ihickson 1013:
1.416 ihickson 1014: <p><a href="//www.whatwg.org/demos/workers/multiviewer/page.html">View this example online</a>.</p>
1.327 ihickson 1015:
1016:
1017: <h4 id="delegation"><span class="secno">1.2.5 </span>Delegation</h4>
1018:
1019: <p><i>This section is non-normative.</i></p>
1020:
1.396 ihickson 1021: <p>With multicore CPUs becoming prevalent, one way to obtain better performance is to split
1022: computationally expensive tasks amongst multiple workers. In this example, a computationally
1023: expensive task that is to be performed for every number from 1 to 10,000,000 is farmed out to ten
1024: subworkers.</p>
1.327 ihickson 1025:
1026: <p>The main page is as follows, it just reports the result:</p>
1027:
1028: <pre><!DOCTYPE HTML>
1.81 ihickson 1029: <html>
1030: <head>
1.203 ihickson 1031: <title>Worker example: Multicore computation</title>
1.81 ihickson 1032: </head>
1033: <body>
1.203 ihickson 1034: <p>Result: <output id="result"></output></p>
1.81 ihickson 1035: <script>
1.50 ihickson 1036: var worker = new Worker('worker.js');
1037: worker.onmessage = function (event) {
1.54 ihickson 1038: document.getElementById('result').textContent = event.data;
1.40 ihickson 1039: };
1.81 ihickson 1040: </script>
1041: </body>
1.327 ihickson 1042: </html></pre>
1043:
1044: <p>The worker itself is as follows:</p>
1045:
1046: <pre>// settings
1.40 ihickson 1047: var num_workers = 10;
1048: var items_per_worker = 1000000;
1049:
1050: // start the workers
1051: var result = 0;
1052: var pending_workers = num_workers;
1053: for (var i = 0; i < num_workers; i += 1) {
1.50 ihickson 1054: var worker = new Worker('core.js');
1055: worker.postMessage(i * items_per_worker);
1056: worker.postMessage((i+1) * items_per_worker);
1057: worker.onmessage = storeResult;
1.40 ihickson 1058: }
1059:
1060: // handle the results
1061: function storeResult(event) {
1.54 ihickson 1062: result += 1*event.data;
1.40 ihickson 1063: pending_workers -= 1;
1064: if (pending_workers <= 0)
1.50 ihickson 1065: postMessage(result); // finished!
1.327 ihickson 1066: }</pre>
1067:
1068: <p>It consists of a loop to start the subworkers, and then a handler
1069: that waits for all the subworkers to respond.</p>
1070:
1071: <p>The subworkers are implemented as follows:</p>
1072:
1073: <pre>var start;
1.41 ihickson 1074: onmessage = getStart;
1.40 ihickson 1075: function getStart(event) {
1.54 ihickson 1076: start = 1*event.data;
1.40 ihickson 1077: onmessage = getEnd;
1078: }
1079:
1080: var end;
1081: function getEnd(event) {
1.54 ihickson 1082: end = 1*event.data;
1.40 ihickson 1083: onmessage = null;
1.66 ihickson 1084: work();
1.40 ihickson 1085: }
1086:
1.66 ihickson 1087: function work() {
1.40 ihickson 1088: var result = 0;
1089: for (var i = start; i < end; i += 1) {
1090: // perform some complex calculation here
1091: result += 1;
1092: }
1.50 ihickson 1093: postMessage(result);
1094: close();
1.327 ihickson 1095: }</pre>
1096:
1.396 ihickson 1097: <p>They receive two numbers in two events, perform the computation for the range of numbers thus
1098: specified, and then report the result back to the parent.</p>
1.327 ihickson 1099:
1.416 ihickson 1100: <p><a href="//www.whatwg.org/demos/workers/multicore/page.html">View this example online</a>.</p>
1.327 ihickson 1101:
1102:
1103:
1104:
1105: <h3 id="tutorials"><span class="secno">1.3 </span>Tutorials</h3>
1106:
1107: <h4 id="creating-a-dedicated-worker"><span class="secno">1.3.1 </span>Creating a dedicated worker</h4>
1108:
1109: <p><i>This section is non-normative.</i></p>
1110:
1.396 ihickson 1111: <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 URL to that file as its only
1112: argument; a worker is then created and returned:</p>
1.327 ihickson 1113:
1114: <pre>var worker = new Worker('helper.js');</pre>
1115:
1116:
1117: <h4 id="communicating-with-a-dedicated-worker"><span class="secno">1.3.2 </span>Communicating with a dedicated worker</h4>
1118:
1119: <p><i>This section is non-normative.</i></p>
1120:
1.397 ihickson 1121: <p>Dedicated workers use <code>MessagePort</code> objects behind the scenes, and thus support all
1.396 ihickson 1122: the same features, such as sending structured data, transferring binary data, and transferring
1123: other ports.</p>
1124:
1125: <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 handler IDL attributes">event
1126: handler IDL attribute</span> on the <code><a href="#worker">Worker</a></code> object:</p>
1.327 ihickson 1127:
1128: <pre>worker.onmessage = function (event) { ... };</pre>
1129:
1.396 ihickson 1130: <p>You can also use the <code title="dom-EventTarget-addEventListener">addEventListener()</code>
1131: method.</p>
1.327 ihickson 1132:
1.397 ihickson 1133: <p class="note">The implicit <code>MessagePort</code> used by dedicated workers has its <span>port
1.396 ihickson 1134: message queue</span> implicitly enabled when it is created, so there is no equivalent to the
1.397 ihickson 1135: <code>MessagePort</code> interface's <code title="dom-MessagePort-start">start()</code> method on
1.396 ihickson 1136: the <code><a href="#worker">Worker</a></code> interface.</p>
1137:
1138: <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. Structured data can be sent over this
1139: communication channel. To send <code>ArrayBuffer</code> objects efficiently (by transferring them
1140: rather than cloning them), list them in an array in the second argument.</p>
1.327 ihickson 1141:
1142: <pre>worker.postMessage({
1.303 ihickson 1143: operation: 'find-edges',
1144: input: buffer, // an ArrayBuffer object
1145: threshold: 0.6,
1.327 ihickson 1146: }, [buffer]);</pre>
1147:
1.396 ihickson 1148: <p>To receive a message inside the worker, the <code title="handler-DedicatedWorkerGlobalScope-onmessage"><a href="#handler-dedicatedworkerglobalscope-onmessage">onmessage</a></code> <span title="event handler
1149: IDL attributes">event handler IDL attribute</span> is used.</p>
1.327 ihickson 1150:
1151: <pre>onmessage = function (event) { ... };</pre>
1152:
1.396 ihickson 1153: <p>You can again also use the <code title="dom-EventTarget-addEventListener">addEventListener()</code> method.</p>
1.327 ihickson 1154:
1155: <p>In either case, the data is provided in the event object's <code title="dom-MessageEvent-data">data</code> attribute.</p>
1156:
1.396 ihickson 1157: <p>To send messages back, you again use <code title="dom-DedicatedWorkerGlobalScope-postMessage"><a href="#dom-dedicatedworkerglobalscope-postmessage">postMessage()</a></code>. It supports the
1158: structured data in the same manner.</p>
1.327 ihickson 1159:
1160: <pre>postMessage(event.data.input, [event.data.input]); // transfer the buffer back</pre>
1161:
1162:
1163: <h4 id="shared-workers"><span class="secno">1.3.3 </span>Shared workers</h4>
1164:
1165: <p><i>This section is non-normative.</i></p>
1166:
1.356 ihickson 1167: <p>Shared workers are identified by the URL of the script used to create it, optionally with an
1168: explicit name. The name allows multiple instances of a particular shared worker to be started.</p>
1169:
1170: <p>Shared workers are scoped by <span>origin</span>. Two different sites using the same names will
1171: not collide. However, if a page tries to use the same shared worker name as another page on the
1172: same site, but with a different script URL, it will fail.</p>
1.327 ihickson 1173:
1.396 ihickson 1174: <p>Creating shared workers is done using the <code title="dom-SharedWorker"><a href="#dom-sharedworker">SharedWorker()</a></code>
1175: constructor. This constructor takes the URL to the script to use for its first argument, and the
1176: name of the worker, if any, as the second argument.</p>
1.327 ihickson 1177:
1178: <pre>var worker = new SharedWorker('service.js');</pre>
1179:
1.397 ihickson 1180: <p>Communicating with shared workers is done with explicit <code>MessagePort</code> objects. The
1.396 ihickson 1181: object returned by the <code title="dom-SharedWorker"><a href="#dom-sharedworker">SharedWorker()</a></code> constructor holds a
1.327 ihickson 1182: reference to the port on its <code title="dom-SharedWorker-port"><a href="#dom-sharedworker-port">port</a></code> attribute.</p>
1183:
1184: <pre>worker.port.onmessage = function (event) { ... };
1.303 ihickson 1185: worker.port.postMessage('some message');
1.327 ihickson 1186: worker.port.postMessage({ foo: 'structured', bar: ['data', 'also', 'possible']});</pre>
1187:
1.408 ihickson 1188: <p>Inside the shared worker, new clients of the worker are announced using the <code title="event-WorkerGlobalScope-connect">connect</code> event. The port for the new client is
1189: given by the event object's <code title="dom-messageevent-source">source</code> attribute.</p>
1.327 ihickson 1190:
1191: <pre>onconnect = function (event) {
1.330 ihickson 1192: var newPort = event.source;
1.303 ihickson 1193: // set up a listener
1194: newPort.onmessage = function (event) { ... };
1195: // send a message back to the port
1196: newPort.postMessage('ready!'); // can also send structured data, of course
1.327 ihickson 1197: };</pre>
1198:
1199:
1200:
1201:
1202:
1203:
1204: <h2 id="conformance-requirements"><span class="secno">2 </span>Conformance requirements</h2>
1205:
1206: <p>All diagrams, examples, and notes in this specification are
1.81 ihickson 1207: non-normative, as are all sections explicitly marked non-normative.
1.327 ihickson 1208: Everything else in this specification is normative.</p>
1209:
1210: <p>The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
1.81 ihickson 1211: "OPTIONAL" in the normative parts of this document are to be
1212: interpreted as described in RFC2119. For readability, these words do
1.327 ihickson 1213: not appear in all uppercase letters in this specification. <a href="#refsRFC2119">[RFC2119]</a></p>
1214:
1215: <p>Requirements phrased in the imperative as part of algorithms
1.81 ihickson 1216: (such as "strip any leading space characters" or "return false and
1217: abort these steps") are to be interpreted with the meaning of the
1218: key word ("must", "should", "may", etc) used in introducing the
1.327 ihickson 1219: algorithm.</p>
1220:
1221: <p>Some conformance requirements are phrased as requirements on
1.81 ihickson 1222: attributes, methods or objects. Such requirements are to be
1.327 ihickson 1223: interpreted as requirements on user agents.</p>
1224:
1225: <p>Conformance requirements phrased as algorithms or specific steps
1.81 ihickson 1226: may be implemented in any manner, so long as the end result is
1227: equivalent. (In particular, the algorithms defined in this
1228: specification are intended to be easy to follow, and not intended to
1.327 ihickson 1229: be performant.)</p>
1230:
1231: <p>The only conformance class defined by this specification is user
1232: agents.</p>
1233:
1234: <p>User agents may impose implementation-specific limits on
1.81 ihickson 1235: otherwise unconstrained inputs, e.g. to prevent denial of service
1236: attacks, to guard against running out of memory, or to work around
1.327 ihickson 1237: platform-specific limitations.</p>
1238:
1239: <p>When support for a feature is disabled (e.g. as an emergency
1.229 ihickson 1240: measure to mitigate a security problem, or to aid in development, or
1241: for performance reasons), user agents must act as if they had no
1242: support for the feature whatsoever, and as if the feature was not
1243: mentioned in this specification. For example, if a particular
1244: feature is accessed via an attribute in a Web IDL interface, the
1245: attribute itself would be omitted from the objects that implement
1246: that interface — leaving the attribute on the object but
1.327 ihickson 1247: making it return null or throw an exception is insufficient.</p>
1248:
1249:
1250: <h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3>
1251:
1252: <p>This specification relies on several other underlying
1253: specifications.</p>
1254:
1255: <dl><dt>HTML</dt>
1.49 ihickson 1256:
1.81 ihickson 1257: <dd>
1.49 ihickson 1258:
1.226 ihickson 1259: <p>Many fundamental concepts from HTML are used by this
1260: specification. <a href="#refsHTML">[HTML]</a></p>
1.49 ihickson 1261:
1.81 ihickson 1262: </dd>
1.1 ihickson 1263:
1.81 ihickson 1264: <dt>WebIDL</dt>
1.1 ihickson 1265:
1266: <dd>
1267:
1.81 ihickson 1268: <p>The IDL blocks in this specification use the semantics of the
1.153 ihickson 1269: WebIDL specification. <a href="#refsWEBIDL">[WEBIDL]</a></p>
1.1 ihickson 1270:
1.81 ihickson 1271: </dd>
1.1 ihickson 1272:
1.327 ihickson 1273: </dl><h2 id="terminology"><span class="secno">3 </span>Terminology</h2>
1274:
1275: <p>The construction "a <code title="">Foo</code> object", where
1.81 ihickson 1276: <code title="">Foo</code> is actually an interface, is sometimes
1277: used instead of the more accurate "an object implementing the
1.327 ihickson 1278: interface <code title="">Foo</code>".</p>
1279:
1280: <p>The term DOM is used to refer to the API set made available to
1.81 ihickson 1281: scripts in Web applications, and does not necessarily imply the
1282: existence of an actual <code>Document</code> object or of any other
1.353 ihickson 1283: <code>Node</code> objects as defined in the DOM specifications. <a href="#refsDOM">[DOM]</a></p>
1.327 ihickson 1284:
1285: <p>An IDL attribute is said to be <em>getting</em> when its value is
1.81 ihickson 1286: being retrieved (e.g. by author script), and is said to be
1.327 ihickson 1287: <em>setting</em> when a new value is assigned to it.</p>
1288:
1289:
1290: <p>The term "JavaScript" is used to refer to ECMA262, rather than
1.103 ihickson 1291: the official term ECMAScript, since the term JavaScript is more
1.327 ihickson 1292: widely known. <a href="#refsECMA262">[ECMA262]</a></p>
1293:
1294:
1295:
1296: <h2 id="infrastructure"><span class="secno">4 </span>Infrastructure</h2>
1297:
1.417 ! ihickson 1298:
1.396 ihickson 1299: <p>There are two kinds of workers; dedicated workers, and shared workers. Dedicated workers, once
1.417 ! ihickson 1300: created, are linked to their creator; but message ports can be used to communicate from a
1.396 ihickson 1301: dedicated worker to multiple other browsing contexts or workers. Shared workers, on the other
1302: hand, are named, and once created any script running in the same <span>origin</span> can obtain a
1303: reference to that worker and communicate with it.</p>
1.327 ihickson 1304:
1305:
1.397 ihickson 1306: <h3 id="the-global-scope"><span class="secno">4.1 </span>The global scope</h3>
1.327 ihickson 1307:
1308: <p>The global scope is the "inside" of a worker.</p>
1309:
1.397 ihickson 1310: <h4 id="the-workerglobalscope-common-interface"><span class="secno">4.1.1 </span>The <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> common interface</h4>
1.327 ihickson 1311:
1.410 ihickson 1312: <pre class="idl">[Exposed=Worker]
1313: interface <dfn id="workerglobalscope">WorkerGlobalScope</dfn> : <span>EventTarget</span> {
1.115 ihickson 1314: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self">self</a>;
1315: readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location">location</a>;
1316:
1317: void <a href="#dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close">close</a>();
1.386 ihickson 1318: attribute <span>OnErrorEventHandler</span> <a href="#handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror">onerror</a>;
1.411 ihickson 1319: attribute <span>EventHandler</span> <a href="#handler-workerglobalscope-onlanguagechange" title="handler-WorkerGlobalScope-onlanguagechange">onlanguagechange</a>;
1.332 ihickson 1320: attribute <span>EventHandler</span> <a href="#handler-workerglobalscope-onoffline" title="handler-WorkerGlobalScope-onoffline">onoffline</a>;
1321: attribute <span>EventHandler</span> <a href="#handler-workerglobalscope-ononline" title="handler-WorkerGlobalScope-ononline">ononline</a>;
1.357 ihickson 1322: };</pre>
1.327 ihickson 1323:
1.362 ihickson 1324: <p>The <dfn id="dom-workerglobalscope-self" title="dom-WorkerGlobalScope-self"><code>self</code></dfn> attribute must return the
1325: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.</p>
1.327 ihickson 1326:
1.362 ihickson 1327: <p>The <dfn id="dom-workerglobalscope-location" title="dom-WorkerGlobalScope-location"><code>location</code></dfn> attribute must
1328: return the <code><a href="#workerlocation">WorkerLocation</a></code> object created for the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1329: object when the worker was created. It represents the <span>absolute URL</span> of the script that
1330: was used to initialize the worker, after any redirects.</p>
1.327 ihickson 1331:
1332: <hr><p>When a script invokes the <dfn id="dom-workerglobalscope-close" title="dom-WorkerGlobalScope-close"><code>close()</code></dfn>
1.362 ihickson 1333: method on a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user agent must run the following steps
1334: (atomically):</p>
1.327 ihickson 1335:
1.362 ihickson 1336: <ol><li><p>Discard any <span title="concept-task">tasks</span> that have been added to the
1.363 ihickson 1337: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's <span>event loop</span>'s <span title="task queue">task
1338: queues</span>.</p>
1.123 ihickson 1339:
1.362 ihickson 1340: <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 true. (This prevents any further
1341: tasks from being queued.)</li>
1.81 ihickson 1342:
1.362 ihickson 1343: </ol><hr><p>The following are the <span>event handlers</span> (and their corresponding <span title="event
1.391 ihickson 1344: handler event type">event handler event types</span>) that must be supported, as <span>event handler IDL attributes</span>,
1.362 ihickson 1345: by objects implementing the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface:</p>
1.327 ihickson 1346:
1347: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.281 ihickson 1348: <tbody><tr><td><dfn id="handler-workerglobalscope-onerror" title="handler-WorkerGlobalScope-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.411 ihickson 1349: <tr><td><dfn id="handler-workerglobalscope-onlanguagechange" title="handler-WorkerGlobalScope-onlanguagechange"><code>onlanguagechange</code></dfn> <td> <code title="event-languagechange">languagechange</code>
1.289 ihickson 1350: <tr><td><dfn id="handler-workerglobalscope-onoffline" title="handler-WorkerGlobalScope-onoffline"><code>onoffline</code></dfn> <td> <code title="event-offline">offline</code>
1351: <tr><td><dfn id="handler-workerglobalscope-ononline" title="handler-WorkerGlobalScope-ononline"><code>ononline</code></dfn> <td> <code title="event-online">online</code>
1.399 ihickson 1352: </table><hr><p class="note">For <span title="data protocol"><code title="">data:</code> URLs</span>, this is
1.408 ihickson 1353: the <span>origin</span> specified by the <span>entry settings object</span> when the constructor
1354: was called. For other <span title="URL">URLs</span>, this is the <span>origin</span> of the value
1355: of the <span>absolute URL</span> given in the worker's <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location"></a></code> attribute.</p>
1.339 ihickson 1356:
1357:
1.397 ihickson 1358: <h4 id="dedicated-workers-and-the-dedicatedworkerglobalscope-interface"><span class="secno">4.1.2 </span>Dedicated workers and the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> interface</h4>
1.327 ihickson 1359:
1.410 ihickson 1360: <pre class="idl">[Global=Worker,DedicatedWorker]
1.388 ihickson 1361: /*sealed*/ interface <dfn id="dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.318 ihickson 1362: void <a href="#dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage">postMessage</a>(any message, optional sequence<<span>Transferable</span>> transfer);
1.332 ihickson 1363: attribute <span>EventHandler</span> <a href="#handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage">onmessage</a>;
1.327 ihickson 1364: };</pre>
1365:
1.396 ihickson 1366: <p><code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects act as if they had an implicit
1.397 ihickson 1367: <code>MessagePort</code> associated with them. This port is part of a channel that is set up when
1.396 ihickson 1368: the worker is created, but it is not exposed. This object must never be garbage collected before
1369: the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.</p>
1.327 ihickson 1370:
1.396 ihickson 1371: <p>All messages received by that port must immediately be retargeted at the
1372: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object.</p>
1.327 ihickson 1373:
1374: <p>The <dfn id="dom-dedicatedworkerglobalscope-postmessage" title="dom-DedicatedWorkerGlobalScope-postMessage"><code>postMessage()</code></dfn>
1.359 ihickson 1375: method on <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> objects must act as if, when invoked, it
1376: immediately invoked <span title="dom-MessagePort-postMessage">the method of the same name</span>
1377: on the port, with the same arguments, and returned the same return value.</p>
1378:
1379:
1.327 ihickson 1380:
1.396 ihickson 1381: <p>The following are the <span>event handlers</span> (and their corresponding <span title="event
1382: handler event type">event handler event types</span>) that must be supported, as <span>event
1383: handler IDL attributes</span>, by objects implementing the <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
1.327 ihickson 1384: interface:</p>
1385:
1386: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1387: <tbody><tr><td><dfn id="handler-dedicatedworkerglobalscope-onmessage" title="handler-DedicatedWorkerGlobalScope-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1.396 ihickson 1388: </table><p>For the purposes of the <span>application cache</span> networking model, a dedicated worker is
1389: an extension of the <span>cache host</span> from which it was created.</p>
1.327 ihickson 1390:
1391:
1392:
1.397 ihickson 1393: <h4 id="shared-workers-and-the-sharedworkerglobalscope-interface"><span class="secno">4.1.3 </span>Shared workers and the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> interface</h4>
1.327 ihickson 1394:
1.410 ihickson 1395: <pre class="idl">[Global=Worker,SharedWorker]
1.388 ihickson 1396: /*sealed*/ interface <dfn id="sharedworkerglobalscope">SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
1.115 ihickson 1397: readonly attribute DOMString <a href="#dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name">name</a>;
1.181 ihickson 1398: readonly attribute <span>ApplicationCache</span> <span title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</span>;
1.332 ihickson 1399: attribute <span>EventHandler</span> <a href="#handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect">onconnect</a>;
1.327 ihickson 1400: };</pre>
1401:
1.398 ihickson 1402: <p>Shared workers receive message ports through <code title="event-WorkerGlobalScope-connect">connect</code> events on their <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object for each
1.396 ihickson 1403: connection.</p>
1404:
1405: <p>The <dfn id="dom-sharedworkerglobalscope-name" title="dom-SharedWorkerGlobalScope-name"><code>name</code></dfn> attribute must return
1406: the value it was assigned when the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object was created by the
1407: "<a href="#run-a-worker">run a worker</a>" algorithm. Its value represents the name that can be used to obtain a
1408: reference to the worker using the <code><a href="#sharedworker">SharedWorker</a></code> constructor.</p>
1.327 ihickson 1409:
1.396 ihickson 1410: <p>The following are the <span>event handlers</span> (and their corresponding <span title="event
1411: handler event type">event handler event types</span>) that must be supported, as <span>event
1412: handler IDL attributes</span>, by objects implementing the <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
1.327 ihickson 1413: interface:</p>
1414:
1415: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.407 ihickson 1416: <tbody><tr><td><dfn id="handler-sharedworkerglobalscope-onconnect" title="handler-SharedWorkerGlobalScope-onconnect"><code>onconnect</code></dfn> <td> <code title="event-WorkerGlobalScope-connect">connect</code>
1.396 ihickson 1417: </table><p>For the purposes of the <span>application cache</span> networking model, a shared worker is its
1418: own <span>cache host</span>. The <a href="#run-a-worker">run a worker</a> algorithm takes care of associating the
1.327 ihickson 1419: worker with an <span>application cache</span>.</p>
1420:
1.396 ihickson 1421: <p class="note">The <code title="dom-SharedWorkerGlobalScope-applicationCache">applicationCache</code> attribute returns the
1422: <code>ApplicationCache</code> object for the worker.</p>
1.327 ihickson 1423:
1424:
1.334 ihickson 1425:
1.409 ihickson 1426: <h3 id="worker-event-loop"><span class="secno">4.2 </span>The event loop</h3>
1.327 ihickson 1427:
1.363 ihickson 1428: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object has a distinct <span>event loop</span>, separate
1429: from those used by <span title="unit of related similar-origin browsing contexts">units of related
1.362 ihickson 1430: similar-origin browsing contexts</span>. This <span>event loop</span> has no associated
1431: <span>browsing context</span>, and its <span title="task queue">task queues</span> only have
1.363 ihickson 1432: events, callbacks, and networking activity as <span title="concept-task">tasks</span>. These <span title="event loop">event loops</span> are created by the <a href="#run-a-worker">run a worker</a> algorithm.</p>
1.327 ihickson 1433:
1.362 ihickson 1434: <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 initially be false, but which
1435: can get set to true by the algorithms in the processing model section below.</p>
1436:
1437: <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 true, the <span>event
1438: loop</span>'s <span title="task queue">task queues</span> must discard any further <span title="concept-task">tasks</span> that would be added to them (tasks already on the queue are
1439: unaffected except where otherwise specified). Effectively, once the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is true, timers stop firing,
1440: notifications for all pending asynchronous operations are dropped, etc.</p>
1.327 ihickson 1441:
1442:
1443:
1.397 ihickson 1444: <h3 id="the-worker-s-lifetime"><span class="secno">4.3 </span>The worker's lifetime</h3>
1.327 ihickson 1445:
1.362 ihickson 1446: <p>Workers communicate with other workers and with <span title="browsing context">browsing
1447: contexts</span> through <span title="channel messaging">message channels</span> and their
1.397 ihickson 1448: <code>MessagePort</code> objects.</p>
1.327 ihickson 1449:
1.362 ihickson 1450: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> <var title="">worker global scope</var> has a list of
1.397 ihickson 1451: <dfn id="the-worker-s-ports">the worker's ports</dfn>, which consists of all the <code>MessagePort</code> objects that are
1.362 ihickson 1452: entangled with another port and that have one (but only one) port owned by <var title="">worker
1.397 ihickson 1453: global scope</var>. This list includes the implicit <code>MessagePort</code> in the case of <a href="#dedicatedworkerglobalscope" title="DedicatedWorkerGlobalScope">dedicated workers</a>.</p>
1.362 ihickson 1454:
1455: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> also has a list of <dfn id="the-worker-s-workers">the worker's workers</dfn>.
1456: Initially this list is empty; it is populated when the worker creates or obtains further
1457: workers.</p>
1458:
1459: <p>Finally, each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> also has a list of <dfn id="the-worker-s-documents">the worker's
1460: <code>Document</code>s</dfn>. Initially this list is empty; it is populated when the worker is
1461: created.</p>
1462:
1463: <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
1464: worker's documents">added to the worker's <code>Document</code>s</dfn>, the user agent must, for
1465: each worker <var title="">q</var> in the list of <a href="#the-worker-s-workers">the worker's workers</a> whose list of
1466: <a href="#the-worker-s-documents">the worker's <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 documents">add <var title="">d</var> to <var title="">q</var>'s <code>WorkerGlobalScope</code> owner's list of <span>the worker's
1.327 ihickson 1467: <code>Document</code>s</span></a>.</p>
1468:
1.362 ihickson 1469: <p>Whenever a <code>Document</code> object is <span title="discard a Document">discarded</span>,
1470: it must be removed from the list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> of each
1471: worker whose list contains that <code>Document</code>.</p>
1472:
1.398 ihickson 1473: <p>Given a <span>settings object</span> <var title="">o</var> when creating or obtaining a
1.362 ihickson 1474: worker, the <dfn id="list-of-relevant-document-objects-to-add">list of relevant <code>Document</code> objects to add</dfn> depends on the type
1.398 ihickson 1475: of <span>global object</span> specified by <var title="">o</var>'s. If <var title="">o</var>
1.408 ihickson 1476: specifies a <span>global object</span> that is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. if we
1477: are creating a nested worker), then the relevant <code>Document</code>s are the <a href="#the-worker-s-documents">the worker's
1478: <code>Document</code>s</a> of the <span>global object</span> specified by <var title="">o</var>. Otherwise, <var title="">o</var> specifies a <span>global object</span> that
1479: is a <code>Window</code> object, and the relevant <code>Document</code> is just the
1480: <span>responsible document</span> specified by <var title="">o</var>.</p>
1.362 ihickson 1481:
1482: <hr><p>A worker is said to be a <dfn id="permissible-worker">permissible worker</dfn> if its list of <a href="#the-worker-s-documents">the worker's
1483: <code>Document</code>s</a> is not empty.</p>
1484:
1.403 ihickson 1485: <p>A worker is said to be an <dfn id="active-needed-worker">active needed worker</dfn> if any of the <code>Document</code>
1486: objects in <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a> are <span>fully active</span>.</p>
1487:
1.408 ihickson 1488: <p>A worker is said to be a <dfn id="protected-worker">protected worker</dfn> if it is an <a href="#active-needed-worker">active needed
1489: worker</a> and either it has outstanding timers, database transactions, or network connections,
1490: or its list of <a href="#the-worker-s-ports">the worker's ports</a> is not empty, or its <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
1491: is actually a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a shared
1492: worker).</p>
1.362 ihickson 1493:
1494: <p>A worker is said to be a <dfn id="suspendable-worker">suspendable worker</dfn> if it is not an <a href="#active-needed-worker">active needed
1495: worker</a> but it is a <a href="#permissible-worker">permissible worker</a>.</p>
1.327 ihickson 1496:
1497:
1.397 ihickson 1498: <h3 id="processing-model"><span class="secno">4.4 </span>Processing model</h3>
1.327 ihickson 1499:
1.408 ihickson 1500: <p>When a user agent is to <dfn id="run-a-worker">run a worker</dfn> for a script with <span>URL</span> <var title="">url</var> and a <span>script settings object</span> <var title="">settings
1501: object</var>, it must run the following steps:</p>
1.327 ihickson 1502:
1.382 ihickson 1503: <ol><li id="worker-processing-model-top">
1.81 ihickson 1504:
1.362 ihickson 1505: <p>Create a separate parallel execution environment (i.e. a separate thread or process or
1506: equivalent construct), and run the rest of these steps asynchronously in that context.</p>
1.81 ihickson 1507:
1.382 ihickson 1508: <p>For the purposes of timing APIs, this is the <dfn id="official-moment-of-creation">official moment of creation</dfn> of the
1509: worker.</p>
1510:
1.81 ihickson 1511: </li>
1.4 ihickson 1512:
1.398 ihickson 1513: <li><p>Let <var title="">worker global scope</var> be the <span>global object</span> specified
1514: by <var title="">settings object</var>.</li>
1515:
1.101 ihickson 1516: <li><p>If <var title="">worker global scope</var> is actually a
1.362 ihickson 1517: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object (i.e. the worker is a shared worker), and there are
1518: any <span title="relevant application cache">relevant application caches</span> that are
1519: identified by a manifest URL with the <span>same origin</span> as <var title="">url</var> and
1520: that have <var title="">url</var> as one of their entries, <em>not</em> excluding entries marked
1.408 ihickson 1521: as <span title="concept-appcache-foreign">foreign</span>, then associate the <var title="">worker global scope</var> with the <span title="concept-appcache-selection">most
1522: appropriate application cache</span> of those that match.</li>
1.101 ihickson 1523:
1.4 ihickson 1524: <li>
1.52 ihickson 1525:
1.408 ihickson 1526: <p>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>, from the <span>origin</span> specified by <var title="">settings
1527: object</var>, using the <span>responsible document</span> specified by <var title="">settings
1528: object</var> as the <span>referrer source</span> (not the specified <span>API referrer
1529: source</span>!), and with the <i>synchronous flag</i> set and the <i>force same-origin flag</i>
1530: set.</p>
1.362 ihickson 1531:
1532: <p>If the attempt fails, then for each <code><a href="#worker">Worker</a></code> or <code><a href="#sharedworker">SharedWorker</a></code> object
1.408 ihickson 1533: associated with <var title="">worker global scope</var>, <span>queue a task</span> to
1534: <span>fire a simple event</span> named <code title="event-error">error</code> at that object.
1535: Abort these steps.</p>
1.7 ihickson 1536:
1.370 ihickson 1537: <p>If the attempt succeeds, then let <var title="">source</var> be the result of running the
1538: <span>UTF-8 decode</span> algorithm on the script resource.</p>
1.81 ihickson 1539:
1.68 ihickson 1540: <p>Let <var title="">language</var> be JavaScript.</p>
1.7 ihickson 1541:
1.362 ihickson 1542: <p class="note">As with <code>script</code> elements, the MIME type of the script is ignored.
1543: Unlike with <code>script</code> elements, there is no way to override the type. It's always
1.170 ihickson 1544: assumed to be JavaScript.</p>
1.81 ihickson 1545:
1546: </li>
1.7 ihickson 1547:
1.362 ihickson 1548: <li><p>In the newly created execution environment, create a <span>JavaScript global
1.408 ihickson 1549: environment</span> whose <i>global object</i> is <var title="">worker global scope</var>. If
1550: <var title="">worker global scope</var> is a <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object,
1551: then this is a <span>dedicated worker environment</span>. Otherwise, <var title="">worker global
1.362 ihickson 1552: scope</var> is a <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object, and this is a <span>shared worker
1553: environment</span>. (In either case, by definition, it is a <span>worker
1554: environment</span>.)</li>
1.338 ihickson 1555:
1.393 ihickson 1556: <li><!-- SCRIPT EXEC -->
1.68 ihickson 1557:
1.398 ihickson 1558: <p>Let <var title="">script</var> be a new <span title="concept-script">script</span>.</p>
1.362 ihickson 1559:
1.398 ihickson 1560: <p>Obtain the appropriate <span>script execution environment</span> for the scripting language
1561: <var title="">language</var> from <var title="">settings object</var>.</p>
1.362 ihickson 1562:
1563: <p>Parse/compile/initialize <var title="">source</var> using that <span>script execution
1564: environment</span>, as appropriate for <var title="">language</var>, and thus obtain a
1.404 ihickson 1565: <span>code entry-point</span>. If the script was not compiled successfully, let the <span>code
1566: entry-point</span> be a no-op script, and act as if a corresponding uncaught script error had
1567: occurred.</p>
1.81 ihickson 1568:
1.398 ihickson 1569: <p>Let <var title="">script</var>'s <span>settings object</span> be <var title="">settings
1570: object</var>.</p>
1.4 ihickson 1571:
1.81 ihickson 1572: </li>
1.4 ihickson 1573:
1574: <li>
1.81 ihickson 1575:
1.362 ihickson 1576: <p><strong>Closing orphan workers</strong>: Start monitoring the worker such that no sooner than
1.408 ihickson 1577: it stops being a <a href="#protected-worker">protected worker</a>, and no later than it stops being a
1578: <a href="#permissible-worker">permissible worker</a>, <var title="">worker global scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is set to true.</p>
1.81 ihickson 1579:
1580: </li>
1.9 ihickson 1581:
1582: <li>
1.7 ihickson 1583:
1.408 ihickson 1584: <p><strong>Suspending workers</strong>: Start monitoring the worker, such that whenever <var title="">worker global scope</var>'s <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false and the worker is a
1585: <a href="#suspendable-worker">suspendable worker</a>, the user agent suspends execution of script in that worker
1586: until such time as either the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag
1587: switches to true or the worker stops being a <a href="#suspendable-worker">suspendable worker</a>.</p>
1.4 ihickson 1588:
1.81 ihickson 1589: </li>
1.68 ihickson 1590:
1591: <li>
1.4 ihickson 1592:
1.408 ihickson 1593: <p><span title="jump to a code entry-point">Jump</span> to the <span title="concept-script">script</span>'s <span>code entry-point</span>, and let that run until it
1594: either returns, fails to catch an exception, or gets prematurely aborted by the "<a href="#kill-a-worker">kill a
1.362 ihickson 1595: worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined below.</p>
1.81 ihickson 1596:
1597: </li>
1.4 ihickson 1598:
1.95 ihickson 1599: <li><p>If <var title="">worker global scope</var> is actually a
1.362 ihickson 1600: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is a dedicated worker), then
1601: enable the <span>port message queue</span> of the worker's implicit port.</li>
1.95 ihickson 1602:
1.4 ihickson 1603: <li>
1.68 ihickson 1604:
1.398 ihickson 1605: <p><strong>Event loop</strong>: Run the <span>responsible
1606: event loop</span> specified by <var title="">settings object</var> until it is destroyed.</p>
1.43 ihickson 1607:
1.363 ihickson 1608: <p class="note">The handling of events or the execution of callbacks by <span title="concept-task">tasks</span> run by the <span>event loop</span> might get prematurely
1.362 ihickson 1609: aborted by the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms
1.81 ihickson 1610: defined below.</p>
1.8 ihickson 1611:
1.363 ihickson 1612: <p class="note">The worker processing model remains on this step until the event loop is
1613: destroyed, which happens after the <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a>
1614: flag is set to true, as described in the <span>event loop</span> processing model.</p>
1.8 ihickson 1615:
1.81 ihickson 1616: </li>
1.8 ihickson 1617:
1618: <li>
1.71 ihickson 1619:
1.362 ihickson 1620: <p>Empty the <var title="">worker global scope</var>'s <span>list of active timers</span>.</p>
1.50 ihickson 1621:
1.81 ihickson 1622: </li>
1.50 ihickson 1623:
1.247 ihickson 1624: <li>
1625:
1.362 ihickson 1626: <p>Disentangle all the ports in the list of <a href="#the-worker-s-ports">the worker's ports</a>.</p>
1.247 ihickson 1627:
1628: </li>
1629:
1.408 ihickson 1630: <li>
1.318 ihickson 1631:
1.403 ihickson 1632:
1633: <p>Empty the worker's list of <a href="#the-worker-s-documents">the worker's <code>Document</code>s</a>.</p>
1634:
1635: </li>
1636:
1.362 ihickson 1637: </ol><hr><p>When a user agent is to <dfn id="kill-a-worker">kill a worker</dfn> it must run the following steps in parallel
1638: with the worker's main loop (the "<a href="#run-a-worker">run a worker</a>" processing model defined above):</p>
1.327 ihickson 1639:
1.362 ihickson 1640: <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 true.</li>
1.81 ihickson 1641:
1.364 ihickson 1642: <li><p>If there are any <span title="concept-task">tasks</span> queued in the
1643: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's <span>event loop</span>'s <span title="task queue">task
1644: queues</span>, discard them without processing them.</li>
1.281 ihickson 1645:
1.81 ihickson 1646: <li><p>Wait a user-agent-defined amount of time.</li>
1647:
1.281 ihickson 1648: <li><p>Abort the script currently running in the worker.</li>
1.81 ihickson 1649:
1.362 ihickson 1650: </ol><p>User agents may invoke the "<a href="#kill-a-worker">kill a worker</a>" processing model on a worker at any
1651: time, e.g. in response to user requests, in response to CPU quota management, or when a worker
1652: stops being an <a href="#active-needed-worker">active needed worker</a> if the worker continues executing even after its
1653: <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag was set to true.</p>
1654:
1655: <hr><p>When a user agent is to <dfn id="terminate-a-worker">terminate a worker</dfn> it must run the following steps in
1656: parallel with the worker's main loop (the "<a href="#run-a-worker">run a worker</a>" processing model defined
1657: above):</p>
1658:
1659: <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 true.</li>
1660:
1.364 ihickson 1661: <li><p>If there are any <span title="concept-task">tasks</span> queued in the
1662: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object's <span>event loop</span>'s <span title="task queue">task
1663: queues</span>, discard them without processing them.</li>
1.81 ihickson 1664:
1665: <li><p>Abort the script currently running in the worker.</li>
1666:
1.362 ihickson 1667: <li><p>If the worker's <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object is actually a
1668: <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is a dedicated worker), then
1669: empty the <span>port message queue</span> of the port that the worker's implicit port is
1.81 ihickson 1670: entangled with.</li>
1671:
1.362 ihickson 1672: </ol><hr><p>The <span>task source</span> for the tasks mentioned above is the <span>DOM manipulation task
1673: source</span>.</p>
1.327 ihickson 1674:
1675:
1.397 ihickson 1676: <h3 id="runtime-script-errors"><span class="secno">4.5 </span>Runtime script errors</h3>
1.327 ihickson 1677:
1.352 ihickson 1678: <p>Whenever an uncaught runtime script error occurs in one of the worker's scripts, if the error
1679: did not occur while handling a previous script error, the user agent must <span>report the
1680: error</span> for that <span title="concept-script">script</span>, with the position (line number
1.386 ihickson 1681: and column number) where the error occurred, using the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object as the target.
1.205 ihickson 1682:
1.226 ihickson 1683: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1684:
1.327 ihickson 1685: </p>
1686:
1.362 ihickson 1687: <p>For shared workers, if the error is still <i title="concept-error-nothandled">not handled</i>
1.386 ihickson 1688: afterwards, the error may be reported to the user.
1.205 ihickson 1689:
1.226 ihickson 1690: <a href="#refsHTML">[HTML]</a>
1.205 ihickson 1691:
1.327 ihickson 1692: </p>
1693:
1.347 ihickson 1694: <p>For dedicated workers, if the error is still <i title="concept-error-nothandled">not
1.386 ihickson 1695: handled</i> afterwards, the user
1696: agent must <span>queue a task</span> to <span title="concept-event-fire">fire</span> a <span title="concept-events-trusted">trusted</span> event that uses the <code>ErrorEvent</code>
1.347 ihickson 1697: interface, with the name <code title="event-error">error</code>, that doesn't bubble and is
1.390 ihickson 1698: cancelable, with its <code title="dom-ErrorEvent-message">message</code>, <code title="dom-ErrorEvent-filename">filename</code>, <code title="dom-ErrorEvent-lineno">lineno</code>, <code title="dom-ErrorEvent-colno">colno</code>,
1.389 ihickson 1699: attributes initialized appropriately,
1700: and with the <code title="dom-ErrorEvent-error">error</code> attribute initialized to null,
1701: at the <code><a href="#worker">Worker</a></code> object associated with the
1.347 ihickson 1702: worker. If the event is not canceled, the user agent must act as if the uncaught runtime script
1703: error had occurred in the global scope that the <code><a href="#worker">Worker</a></code> object is in, thus repeating
1704: the entire runtime script error reporting process one level up.</p>
1.327 ihickson 1705:
1.362 ihickson 1706: <p>If the implicit port connecting the worker to its <code><a href="#worker">Worker</a></code> object has been
1707: disentangled (i.e. if the parent worker has been terminated), then the user agent must act as if
1708: the <code><a href="#worker">Worker</a></code> object had no <code title="event-error">error</code> event handler and as
1709: if that worker's <code title="handler-WorkerGlobalScope-onerror"><a href="#handler-workerglobalscope-onerror">onerror</a></code> attribute was
1710: null, but must otherwise act as described above.</p>
1711:
1712: <p class="note">Thus, error reports propagate up to the chain of dedicated workers up to the
1713: original <code>Document</code>, even if some of the workers along this chain have been terminated
1714: and garbage collected.</p>
1.327 ihickson 1715:
1.362 ihickson 1716: <p>The <span>task source</span> for the task mentioned above is the <span>DOM manipulation task
1717: source</span>.</p>
1.327 ihickson 1718:
1719:
1.397 ihickson 1720: <h3 id="creating-workers"><span class="secno">4.6 </span>Creating workers</h3>
1.327 ihickson 1721:
1.397 ihickson 1722: <h4 id="the-abstractworker-abstract-interface"><span class="secno">4.6.1 </span>The <code><a href="#abstractworker">AbstractWorker</a></code> abstract interface</h4>
1.327 ihickson 1723:
1.410 ihickson 1724: <pre class="idl">[NoInterfaceObject, Exposed=Window,Worker]
1.317 ihickson 1725: interface <dfn id="abstractworker">AbstractWorker</dfn> {
1.332 ihickson 1726: attribute <span>EventHandler</span> <a href="#handler-abstractworker-onerror" title="handler-AbstractWorker-onerror">onerror</a>;
1.327 ihickson 1727: };</pre>
1728:
1729: <p>The following are the <span>event handlers</span> (and their
1.177 ihickson 1730: corresponding <span title="event handler event type">event handler
1.391 ihickson 1731: event types</span>) that must be supported, as <span>event handler IDL attributes</span>, by
1.327 ihickson 1732: objects implementing the <code><a href="#abstractworker">AbstractWorker</a></code> interface:</p>
1733:
1734: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1735: <tbody><tr><td><dfn id="handler-abstractworker-onerror" title="handler-AbstractWorker-onerror"><code>onerror</code></dfn> <td> <code title="event-error">error</code>
1.398 ihickson 1736: </table><h4 id="script-settings-for-workers"><span class="secno">4.6.2 </span>Script settings for workers</h4>
1737:
1738: <p>When the user agent is required to <dfn id="set-up-a-worker-script-settings-object">set up a worker script settings object</dfn>, given a
1.408 ihickson 1739: <var title="">worker global scope</var> and a <span>URL</span> <var title="">script
1740: address</var>, it must run the following steps:</p>
1.398 ihickson 1741:
1742: <ol><li><p>Let <var title="">inherited responsible browsing context</var> be the <span>responsible
1.408 ihickson 1743: browsing context</span> specified by the <span>incumbent settings object</span>.</li>
1.399 ihickson 1744:
1.398 ihickson 1745: <li><p>Let <var title="">inherited responsible document</var> be the <span>responsible
1.408 ihickson 1746: document</span> specified by the <span>incumbent settings object</span>.</li>
1.398 ihickson 1747:
1.399 ihickson 1748: <li><p>Let <var title="">inherited origin</var> be the <span>origin</span> specified by the
1749: <span>incumbent settings object</span>.</li>
1750:
1.398 ihickson 1751: <li><p>Let <var title="">worker event loop</var> be a newly created <span>event
1752: loop</span>.</li>
1753:
1754: <li>
1755:
1756: <p>Let <var title="">settings object</var> be a new <span>script settings object</span> whose
1757: algorithms are defined as follows:</p>
1758:
1759: <dl><dt>The <span title="script execution environment">script execution environments</span></dt>
1760: <dd>
1761:
1762: <p>When the <span>script settings object</span> is created, for each language supported by the
1763: user agent, create an appropriate execution environment as defined by the relevant
1764: specification.</p>
1765:
1766: <p>When a <span>script execution environment</span> is needed, return the appropriate one from
1767: those created when the <span>script settings object</span> was created.</p>
1768:
1769: <p class="note">Currently, workers only support JavaScript, so only a JavaScript execution
1770: environment is actually needed here.</p>
1771:
1772: </dd>
1773:
1774: <dt>The <span>global object</span></dt>
1775: <dd>
1776:
1777: <p>Return <var title="">worker global scope</var>.</p>
1778:
1779: </dd>
1780:
1781: <dt>The <span>responsible browsing context</span></dt>
1782: <dd>
1783:
1784: <p>Return <var title="">inherited responsible browsing context</var>.</p>
1785:
1786: </dd>
1787:
1788: <dt>The <span>responsible document</span></dt>
1789: <dd>
1790:
1791: <p>Return <var title="">inherited responsible document</var>.</p>
1792:
1793: </dd>
1794:
1795: <dt>The <span>responsible event loop</span></dt>
1796: <dd>
1797:
1798: <p>Return <var title="">worker event loop</var>.</p>
1799:
1800: </dd>
1801:
1802: <dt>The <span>API referrer source</span></dt>
1803: <dd>
1804:
1.400 ihickson 1805: <p>Return <var title="">script address</var>.</p>
1.398 ihickson 1806:
1807: </dd>
1808:
1809: <dt>The <span>API URL character encoding</span></dt>
1810: <dd>
1811:
1812: <p>Return UTF-8.</p>
1813:
1814: </dd>
1815:
1816: <dt>The <span>API base URL</span></dt>
1817: <dd>
1818:
1819: <p>Return <var title="">worker URL</var>.</p>
1820:
1821: </dd>
1822:
1.399 ihickson 1823: <dt>The <span>origin</span> and <span>effective script origin</span></dt>
1824: <dd>
1825:
1826: <p>Return <var title="">inherited origin</var>.</p>
1827:
1828: </dd>
1829:
1.398 ihickson 1830: </dl></li>
1831:
1832: <li><p>Return <var title="">settings object</var>.</li>
1833:
1834: </ol><h4 id="dedicated-workers-and-the-worker-interface"><span class="secno">4.6.3 </span>Dedicated workers and the <code><a href="#worker">Worker</a></code> interface</h4>
1.327 ihickson 1835:
1.410 ihickson 1836: <pre class="idl">[<a href="#dom-worker" title="dom-Worker">Constructor</a>(DOMString scriptURL), Exposed=Window,Worker]
1.317 ihickson 1837: interface <dfn id="worker">Worker</dfn> : <span>EventTarget</span> {
1.115 ihickson 1838: void <a href="#dom-worker-terminate" title="dom-Worker-terminate">terminate</a>();
1.50 ihickson 1839:
1.318 ihickson 1840: void <a href="#dom-worker-postmessage" title="dom-Worker-postMessage">postMessage</a>(any message, optional sequence<<span>Transferable</span>> transfer);
1.332 ihickson 1841: attribute <span>EventHandler</span> <a href="#handler-worker-onmessage" title="handler-Worker-onmessage">onmessage</a>;
1.317 ihickson 1842: };
1.327 ihickson 1843: <a href="#worker">Worker</a> implements <a href="#abstractworker">AbstractWorker</a>;</pre>
1844:
1.366 ihickson 1845: <p>The <dfn id="dom-worker-terminate" title="dom-Worker-terminate"><code>terminate()</code></dfn> method, when invoked, must
1.371 ihickson 1846: cause the "<a href="#terminate-a-worker">terminate a worker</a>" algorithm to be run on the worker with which the object
1.366 ihickson 1847: is associated.</p>
1848:
1.397 ihickson 1849: <p><code><a href="#worker">Worker</a></code> objects act as if they had an implicit <code>MessagePort</code> associated
1.366 ihickson 1850: with them. This port is part of a channel that is set up when the worker is created, but it is not
1851: exposed. This object must never be garbage collected before the <code><a href="#worker">Worker</a></code> object.</p>
1.327 ihickson 1852:
1.366 ihickson 1853: <p>All messages received by that port must immediately be retargeted at the <code><a href="#worker">Worker</a></code>
1854: object.</p>
1.327 ihickson 1855:
1.359 ihickson 1856: <p>The <dfn id="dom-worker-postmessage" title="dom-Worker-postMessage"><code>postMessage()</code></dfn> method on
1857: <code><a href="#worker">Worker</a></code> objects must act as if, when invoked, it immediately invoked <span title="dom-MessagePort-postMessage">the method of the same name</span> on the port, with the same
1858: arguments, and returned the same return value.</p>
1859:
1860:
1.327 ihickson 1861:
1862: <div class="example">
1.319 ihickson 1863:
1864: <p>The <code title="dom-Worker-postMessage"><a href="#dom-worker-postmessage">postMessage()</a></code>
1865: method's first argument can be structured data:</p>
1866:
1867: <pre>worker.postMessage({opcode: 'activate', device: 1938, parameters: [23, 102]});</pre>
1868:
1.327 ihickson 1869: </div>
1870:
1.366 ihickson 1871: <p>The following are the <span>event handlers</span> (and their corresponding <span title="event
1.391 ihickson 1872: handler event type">event handler event types</span>) that must be supported, as <span>event handler IDL attributes</span>,
1.366 ihickson 1873: by objects implementing the <code><a href="#worker">Worker</a></code> interface:</p>
1.327 ihickson 1874:
1875: <table><thead><tr><th><span title="event handlers">Event handler</span> <th><span>Event handler event type</span>
1.155 ihickson 1876: <tbody><tr><td><dfn id="handler-worker-onmessage" title="handler-Worker-onmessage"><code>onmessage</code></dfn> <td> <code title="event-message">message</code>
1877: </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 1878: user agent must run the following steps:</p>
1879:
1.349 ihickson 1880: <ol><li><p>The user agent may throw a <code>SecurityError</code> exception and abort these steps if
1881: the request violates a policy decision (e.g. if the user agent is configured to not allow the
1882: page to start dedicated workers).</li>
1883:
1.366 ihickson 1884: <li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument
1.408 ihickson 1885: relative to the <span>API base URL</span> specified by the <span>entry settings object</span>
1886: when the method was invoked.</li>
1.9 ihickson 1887:
1.374 ihickson 1888: <li><p>If this fails, throw a <code>SyntaxError</code> exception and abort these steps.</li>
1.9 ihickson 1889:
1.398 ihickson 1890: <li><p>Let <var title="">worker URL</var> be the resulting <span>absolute URL</span>.</li>
1891:
1.167 ihickson 1892: <li>
1893:
1.408 ihickson 1894: <p>If the <span title="concept-url-scheme">scheme</span> component of <var title="">worker
1895: URL</var> is not "<code title="data-protocol">data</code>", and the <span>origin</span> of <var title="">worker URL</var> is not the <span title="same origin">same</span> as the
1896: <span>origin</span> specified by the <span>incumbent settings object</span>, then throw a
1897: <code>SecurityError</code> exception and abort these steps.</p>
1.366 ihickson 1898:
1.415 ihickson 1899: <p class="note">For example, scripts can be external files with the same scheme, host, and port
1900: as the original page, or <span title="data protocol"><code title="">data:</code> URLs</span>,
1901: or same-origin <code title="">blob:</code> URLs. Thus, an <code>http:</code> page couldn't
1902: start workers using scripts with <code>http:</code> URLs. <a href="#refsFILEAPI">[FILEAPI]</a>.</p>
1.167 ihickson 1903:
1904: </li>
1.9 ihickson 1905:
1.408 ihickson 1906: <li><p>Create a new <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> object. Let <var title="">worker
1907: global scope</var> be this new object.</li>
1.400 ihickson 1908:
1.398 ihickson 1909: <li><p><a href="#set-up-a-worker-script-settings-object">Set up a worker script settings object</a> with <var title="">worker global
1.408 ihickson 1910: scope</var> and <var title="">worker URL</var>, and let <var title="">settings object</var> be
1911: the result.</li>
1.398 ihickson 1912:
1.366 ihickson 1913: <li><p>Create a new <code><a href="#worker">Worker</a></code> object, associated with <var title="">worker global
1914: scope</var>. Let <var title="">worker</var> be this new object.</li>
1915:
1.408 ihickson 1916: <li><p><span>Create a new <code>MessagePort</code> object</span> whose <span title="concept-port-owner">owner</span> is the <span>incumbent settings object</span>. Let this
1917: be the <var title="">outside port</var>.</li>
1.9 ihickson 1918:
1.81 ihickson 1919: <li><p>Associate the <var title="">outside port</var> with <var title="">worker</var>.</li>
1.50 ihickson 1920:
1.414 ihickson 1921: <li><p><span>Create a new <code>MessagePort</code> object</span> whose <span title="concept-port-owner">owner</span> is <var title="">script settings</var>. Let <var title="">inside port</var> be this new object.</li>
1.50 ihickson 1922:
1.366 ihickson 1923: <li><p>Associate <var title="">inside port</var> with <var title="">worker global
1924: scope</var>.</li>
1.50 ihickson 1925:
1.366 ihickson 1926: <li><p><span>Entangle</span> <var title="">outside port</var> and <var title="">inside
1927: port</var>.</li>
1.50 ihickson 1928:
1.366 ihickson 1929: <li><p>Return <var title="">worker</var>, and run the following steps asynchronously.</li>
1.50 ihickson 1930:
1931:
1.318 ihickson 1932:
1.366 ihickson 1933: <li><p>Enable <var title="">outside port</var>'s <span>port message queue</span>.</li>
1.50 ihickson 1934:
1.408 ihickson 1935: <li><p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant <code>Document</code> objects
1936: to add</a> given the <span>incumbent settings object</span>.</li>
1.398 ihickson 1937:
1.408 ihickson 1938: <li><p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to <var title="">worker
1939: global scope</var>'s list of <span>the worker's <code>Document</code>s</span></a> the
1940: <code>Document</code> objects in <var title="">docs</var>.</li>
1941:
1942: <li><p>If the <span>global object</span> specified by the <span>incumbent settings object</span>
1943: is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object (i.e. we are creating a nested worker), add <var title="">worker global scope</var> to the list of <a href="#the-worker-s-workers">the worker's workers</a> of the
1944: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object that is the <span>global object</span> specified by the
1945: <span>incumbent settings object</span>.</li>
1.123 ihickson 1946:
1.408 ihickson 1947: <li><p><a href="#run-a-worker">Run a worker</a> for the script with <span>URL</span> <var title="">worker
1948: URL</var> and the <span>script settings object</span> <var title="">settings
1949: object</var>.</li>
1.4 ihickson 1950:
1.398 ihickson 1951: </ol><h4 id="shared-workers-and-the-sharedworker-interface"><span class="secno">4.6.4 </span>Shared workers and the <code><a href="#sharedworker">SharedWorker</a></code> interface</h4>
1.327 ihickson 1952:
1.410 ihickson 1953: <pre class="idl">[<a href="#dom-sharedworker" title="dom-SharedWorker">Constructor</a>(DOMString scriptURL, optional DOMString name), Exposed=Window,Worker]
1.317 ihickson 1954: interface <dfn id="sharedworker">SharedWorker</dfn> : <span>EventTarget</span> {
1.397 ihickson 1955: readonly attribute <span>MessagePort</span> <a href="#dom-sharedworker-port" title="dom-SharedWorker-port">port</a>;
1.317 ihickson 1956: };
1.327 ihickson 1957: <a href="#sharedworker">SharedWorker</a> implements <a href="#abstractworker">AbstractWorker</a>;</pre>
1958:
1.366 ihickson 1959: <p>The <dfn id="dom-sharedworker-port" title="dom-SharedWorker-port"><code>port</code></dfn> attribute must return the value
1.397 ihickson 1960: it was assigned by the object's constructor. It represents the <code>MessagePort</code> for
1.327 ihickson 1961: communicating with the shared worker.</p>
1962:
1.366 ihickson 1963: <p>When the <dfn id="dom-sharedworker" title="dom-SharedWorker"><code>SharedWorker(<var title="">scriptURL</var>, <var title="">name</var>)</code></dfn> constructor is invoked, the user agent must run the following
1.327 ihickson 1964: steps:</p>
1965:
1.349 ihickson 1966: <ol><li><p>The user agent may throw a <code>SecurityError</code> exception and abort these steps if
1967: the request violates a policy decision (e.g. if the user agent is configured to not allow the
1968: page to start shared workers).</li>
1969:
1.366 ihickson 1970: <li><p><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var>
1971: argument.</li>
1.81 ihickson 1972:
1.374 ihickson 1973: <li><p>If this fails, throw a <code>SyntaxError</code> exception and abort these steps.</li>
1.81 ihickson 1974:
1.374 ihickson 1975: <li><p>Let <var title="">scriptURL</var> be the resulting <span>absolute URL</span> and <var title="">parsed scriptURL</var> be the resulting <span>parsed URL</span>.</li>
1.159 ihickson 1976:
1.366 ihickson 1977: <li><p>Let <var title="">name</var> be the value of the second argument, or the empty string if
1978: the second argument was omitted.</li>
1.159 ihickson 1979:
1.167 ihickson 1980: <li>
1981:
1.366 ihickson 1982: <p>If the <span title="concept-url-scheme">scheme</span> component of <var title="">parsed
1.408 ihickson 1983: scriptURL</var> is not "<code title="data-protocol">data</code>", and the <span>origin</span>
1984: of <var title="">scriptURL</var> is not the <span title="same origin">same</span> as the
1985: <span>origin</span> specified by the <span>incumbent settings object</span>, then throw a
1986: <code>SecurityError</code> exception and abort these steps.</p>
1.401 ihickson 1987:
1.366 ihickson 1988: <p class="note">Thus, scripts must either be external files with the same scheme, host, and port
1989: as the original page, or <span title="data protocol"><code title="">data:</code> URLs</span>.
1.413 ihickson 1990: For example, an <code>http:</code> page couldn't start workers using scripts with
1.408 ihickson 1991: <code>http:</code> URLs.</p>
1.167 ihickson 1992:
1993: </li>
1.9 ihickson 1994:
1995: <li>
1996:
1.366 ihickson 1997: <p>Let <var title="">docs</var> be the <a href="#list-of-relevant-document-objects-to-add">list of relevant <code>Document</code> objects to
1.399 ihickson 1998: add</a> given the <span>incumbent settings object</span>.</p>
1.123 ihickson 1999:
2000: </li>
2001:
2002: <li>
2003:
1.50 ihickson 2004: <p>Execute the following substeps atomically:</p>
1.9 ihickson 2005:
1.366 ihickson 2006: <ol><li><p>Create a new <code><a href="#sharedworker">SharedWorker</a></code> object, which will shortly be associated with a
2007: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object. Let this <code><a href="#sharedworker">SharedWorker</a></code> object be <var title="">worker</var>.</li>
2008:
1.408 ihickson 2009: <li><p><span>Create a new <code>MessagePort</code> object</span> whose <span title="concept-port-owner">owner</span> is the <span>incumbent settings object</span>. Let
1.366 ihickson 2010: this be the <var title="">outside port</var>.</li>
1.81 ihickson 2011:
1.115 ihickson 2012: <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 2013:
1.366 ihickson 2014: <li><p>Let <var title="">worker global scope</var> be null.</li>
1.164 ihickson 2015:
1.312 ihickson 2016: <li>
2017:
1.366 ihickson 2018: <p>If <var title="">name</var> is not the empty string and there exists a
1.408 ihickson 2019: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is exactly equal to <var title="">name</var>, and that is the <span>global object</span> specified by a <span>script
2020: settings object</span> that specifies as its <span>origin</span> the <span>same origin</span>
2021: as the <span>origin</span> of <var title="">scriptURL</var>, then let <var title="">worker
2022: global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</p>
1.366 ihickson 2023:
2024: <p>Otherwise, if <var title="">name</var> is the empty string and there exists a
2025: <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object whose <a href="#dom-workerglobalscope-closing" title="dom-WorkerGlobalScope-closing">closing</a> flag is false, whose <code title="dom-WorkerGlobalScope-name">name</code> attribute is the empty string, and whose <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute represents an <span>absolute
2026: URL</span> that is exactly equal to <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object.</p>
1.312 ihickson 2027:
2028: </li>
2029:
2030: <li>
2031:
1.366 ihickson 2032: <p>If <var title="">worker global scope</var> is not null, but the user agent has been
1.408 ihickson 2033: configured to disallow communication between the worker represented by the <var title="">worker global scope</var> and the <span title="concept-script">scripts</span> whose
2034: <span title="settings object">settings objects</span> are the <span>incumbent settings
2035: object</span>, then set <var title="">worker global scope</var> to null.</p>
1.366 ihickson 2036:
2037: <p class="note">For example, a user agent could have a development mode that isolates a
2038: particular <span>top-level browsing context</span> from all other pages, and scripts in that
2039: development mode could be blocked from connecting to shared workers running in the normal
2040: browser mode.</p>
1.312 ihickson 2041:
2042: </li>
1.164 ihickson 2043:
1.9 ihickson 2044: <li>
2045:
1.366 ihickson 2046: <p>If <var title="">worker global scope</var> is not null, then run these steps:</p>
2047:
2048: <ol><li><p>If <var title="">worker global scope</var>'s <code title="dom-WorkerGlobalScope-location"><a href="#dom-workerglobalscope-location">location</a></code> attribute represents an <span>absolute
2049: URL</span> that is not exactly equal to <var title="">scriptURL</var>, then throw a
2050: <code>URLMismatchError</code> exception and abort all these steps.</li>
2051:
2052: <li><p>Associate <var title="">worker</var> with <var title="">worker global
2053: scope</var>.</li>
1.81 ihickson 2054:
1.398 ihickson 2055: <li><p>Let <var title="">settings object</var> be the <span>script settings object</span>
2056: whose <span>global object</span> is <var title="">worker global scope</var>.</li>
2057:
1.408 ihickson 2058: <li><p><span>Create a new <code>MessagePort</code> object</span> whose <span title="concept-port-owner">owner</span> is <var title="">settings object</var>. Let this be
2059: the <var title="">inside port</var>.</li>
1.81 ihickson 2060:
2061: <li><p><span>Entangle</span> <var title="">outside port</var>
2062: and <var title="">inside port</var>.</li>
2063:
1.344 ihickson 2064: <li><p>Create a <span title="concept-events-trusted">trusted</span> event that uses the
1.408 ihickson 2065: <code>MessageEvent</code> interface, with the name <code title="event-WorkerGlobalScope-connect">connect</code>, which does not bubble, is not
2066: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code>
2067: attribute whose value is initialized to the empty string, has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value is initialized to a <span title="dfn-read-only-array">read only</span> array containing only the newly created port,
2068: and has a <code title="dom-MessageEvent-source">source</code> attribute whose value is
2069: initialized to the newly created port, and <span>queue a task</span> to <span title="concept-event-dispatch">dispatch</span> the event at <var title="">worker global
1.347 ihickson 2070: scope</var>.</li>
1.43 ihickson 2071:
1.123 ihickson 2072: <li>
2073:
1.366 ihickson 2074: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to <var title="">worker global
2075: scope</var>'s list of <span>the worker's <code>Document</code>s</span></a> the
1.123 ihickson 2076: <code>Document</code> objects in <var title="">docs</var>.</p>
2077:
2078: </li>
2079:
1.124 ihickson 2080: <li>
2081:
1.408 ihickson 2082: <p>If the <span>global object</span> specified by the <span>incumbent settings object</span>
2083: is a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to
2084: the list of <a href="#the-worker-s-workers">the worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
2085: that is the <span>global object</span> specified by the <span>incumbent settings
2086: object</span>.</p>
1.124 ihickson 2087:
2088: </li>
2089:
1.373 ihickson 2090: <li><p>Return <var title="">worker</var> and abort all these steps.</li>
1.9 ihickson 2091:
1.155 ihickson 2092: </ol></li>
1.9 ihickson 2093:
1.398 ihickson 2094: <!-- OTHERWISE: -->
2095:
1.408 ihickson 2096: <li><p>Create a new <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> object. Let <var title="">worker
2097: global scope</var> be this new object.</li>
1.400 ihickson 2098:
1.398 ihickson 2099: <li><p><a href="#set-up-a-worker-script-settings-object">Set up a worker script settings object</a> with <var title="">worker global
1.408 ihickson 2100: scope</var> and <var title="">scriptURL</var>, and let <var title="">settings object</var> be
2101: the result.</li>
1.398 ihickson 2102:
1.366 ihickson 2103: <li><p>Associate <var title="">worker</var> with <var title="">worker global
2104: scope</var>.</li>
1.9 ihickson 2105:
1.366 ihickson 2106: <li><p>Set the <code title="dom-SharedWorkerGlobalScope-name"><a href="#dom-sharedworkerglobalscope-name">name</a></code> attribute of <var title="">worker global scope</var> to <var title="">name</var>.</li>
1.9 ihickson 2107:
1.408 ihickson 2108: <li><p><span>Create a new <code>MessagePort</code> object</span> whose <span title="concept-port-owner">owner</span> is <var title="">settings object</var>. Let <var title="">inside port</var> be this new object.</li>
1.9 ihickson 2109:
1.366 ihickson 2110: <li><p><span>Entangle</span> <var title="">outside port</var> and <var title="">inside
2111: port</var>.</li>
1.9 ihickson 2112:
1.155 ihickson 2113: </ol></li>
1.28 ihickson 2114:
1.366 ihickson 2115: <li><p>Return <var title="">worker</var> and perform the remaining steps asynchronously.</li>
1.18 ihickson 2116:
1.344 ihickson 2117: <li><p>Create a <span title="concept-events-trusted">trusted</span> event that uses the
1.408 ihickson 2118: <code>MessageEvent</code> interface, with the name <code title="event-WorkerGlobalScope-connect">connect</code>, which does not bubble, is not
2119: cancelable, has no default action, has a <code title="dom-MessageEvent-data">data</code>
2120: attribute whose value is initialized to the empty string, has a <code title="dom-MessageEvent-ports">ports</code> attribute whose value is initialized to a <span title="dfn-read-only-array">read only</span> array containing only the newly created port, and
2121: has a <code title="dom-MessageEvent-source">source</code> attribute whose value is initialized
2122: to the newly created port, and <span>queue a task</span> to <span title="concept-event-dispatch">dispatch</span> the event at <var title="">worker global
1.347 ihickson 2123: scope</var>.</li>
1.26 ihickson 2124:
2125: <li>
1.46 ihickson 2126:
1.366 ihickson 2127: <p><a href="#add-a-document-to-the-worker-s-documents" title="add a document to the worker's documents">Add to <var title="">worker global
2128: scope</var>'s list of <span>the worker's <code>Document</code>s</span></a> the
1.123 ihickson 2129: <code>Document</code> objects in <var title="">docs</var>.</p>
2130:
2131: </li>
2132:
2133: <li>
2134:
1.408 ihickson 2135: <p>If the <span>global object</span> specified by the <span>incumbent settings object</span> is
2136: a <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to the
2137: list of <a href="#the-worker-s-workers">the worker's workers</a> of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
2138: the <span>global object</span> specified by the <span>incumbent settings object</span>.</p>
1.124 ihickson 2139:
2140: </li>
2141:
2142: <li>
2143:
1.408 ihickson 2144: <p><a href="#run-a-worker">Run a worker</a> for the script with <span>URL</span> <var title="">scriptURL</var>
2145: and the <span>script settings object</span> <var title="">settings object</var>.</p>
1.26 ihickson 2146:
1.60 ihickson 2147: </li>
1.81 ihickson 2148:
1.381 ihickson 2149: </ol><p>The <span>task source</span> for the tasks mentioned above is the <span>DOM manipulation task
1.366 ihickson 2150: source</span>.</p>
1.327 ihickson 2151:
2152:
2153:
2154: <h2 id="apis-available-to-workers"><span class="secno">5 </span>APIs available to workers</h2>
2155:
1.410 ihickson 2156: <pre class="idl">[Exposed=Worker]
2157: partial interface <a href="#workerglobalscope" id="WorkerGlobalScope-partial">WorkerGlobalScope</a> {
1.306 ihickson 2158: void <a href="#dom-workerglobalscope-importscripts" title="dom-WorkerGlobalScope-importScripts">importScripts</a>(DOMString... urls);
1.210 ihickson 2159: readonly attribute <a href="#workernavigator">WorkerNavigator</a> <a href="#dom-worker-navigator" title="dom-worker-navigator">navigator</a>;
1.150 ihickson 2160: };
1.357 ihickson 2161: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <span>WindowTimers</span>;
2162: <a href="#workerglobalscope">WorkerGlobalScope</a> implements <span>WindowBase64</span>;</pre>
1.327 ihickson 2163:
2164:
2165: <h3 id="importing-scripts-and-libraries"><span class="secno">5.1 </span>Importing scripts and libraries</h3>
2166:
1.392 ihickson 2167: <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 <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user
2168: agent must run the following steps:</p>
1.378 ihickson 2169:
1.392 ihickson 2170: <ol><li><p>If there are no arguments, return without doing anything. Abort these steps.</li>
1.327 ihickson 2171:
1.408 ihickson 2172: <li><p>Let <var title="">settings object</var> be the <span>incumbent settings
2173: object</span>.</li>
1.398 ihickson 2174:
1.392 ihickson 2175: <li><p><span title="resolve a url">Resolve</span> each argument.</li>
1.81 ihickson 2176:
1.392 ihickson 2177: <li><p>If any fail, throw a <code>SyntaxError</code> exception and abort these steps.</li>
1.81 ihickson 2178:
1.26 ihickson 2179: <li>
1.81 ihickson 2180:
1.408 ihickson 2181: <p>Attempt to <span>fetch</span> each resource identified by the resulting <span title="absolute URL">absolute URLs</span>, from the <span>origin</span> specified by <var title="">settings object</var>, using the <span>API referrer source</span> specified by <var title="">settings object</var>, and with the <i>synchronous flag</i> set.</p>
1.318 ihickson 2182:
1.81 ihickson 2183: </li>
1.26 ihickson 2184:
2185: <li>
2186:
1.392 ihickson 2187: <p>For each argument in turn, in the order given, starting with the first one, run these
2188: substeps:</p>
1.26 ihickson 2189:
1.155 ihickson 2190: <ol><li>
1.26 ihickson 2191:
1.392 ihickson 2192: <p>Wait for the fetching attempt for the corresponding resource to complete.</p>
1.60 ihickson 2193:
1.392 ihickson 2194: <p>If the fetching attempt failed, throw a <code>NetworkError</code> exception and abort all
2195: these steps.</p>
1.45 ihickson 2196:
1.370 ihickson 2197: <p>If the attempt succeeds, then let <var title="">source</var> be the result of running the
2198: <span>UTF-8 decode</span> algorithm on the script resource.</p>
1.85 ihickson 2199:
2200: <p>Let <var title="">language</var> be JavaScript.</p>
1.61 ihickson 2201:
1.392 ihickson 2202: <p class="note">As with the worker's script, the script here is always assumed to be
2203: JavaScript, regardless of the MIME type.</p>
1.61 ihickson 2204:
1.81 ihickson 2205: </li>
1.26 ihickson 2206:
1.81 ihickson 2207: <li>
1.26 ihickson 2208:
1.398 ihickson 2209: <p><span>Create a script</span> using <var title="">source</var> as the script source, the
2210: <span>URL</span> from which <var title="">source</var> was obtained, <var title="">language</var> as the scripting language, and <var title="">settings object</var> as
2211: the <span>script settings object</span>.</p>
1.81 ihickson 2212:
1.352 ihickson 2213: <p>If the script came from a resource whose <span>URL</span> does not have the <span>same
1.408 ihickson 2214: origin</span> as the <span>origin</span> specified by the <span>incumbent settings
2215: object</span>, then pass the <var title="">muted errors</var> flag to the <span>create a
2216: script</span> algorithm as well.</p>
1.352 ihickson 2217:
1.115 ihickson 2218: <p>Let the newly created <span title="concept-script">script</span> run until it either
1.392 ihickson 2219: returns, fails to parse, fails to catch an exception, or gets prematurely aborted by the
2220: "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms defined
2221: above.</p>
2222:
2223: <p>If it failed to parse, then throw an ECMAScript <code title="js-SyntaxError">SyntaxError</code> exception and abort all these steps. <a href="#refsECMA262">[ECMA262]</a></p>
2224:
2225: <p>If an exception was thrown or if the script was prematurely aborted, then abort all these
1.399 ihickson 2226: steps, letting the exception or aborting continue to be processed by the calling <span title="concept-script">script</span>.</p>
1.392 ihickson 2227:
2228: <p>If the "<a href="#kill-a-worker">kill a worker</a>" or "<a href="#terminate-a-worker">terminate a worker</a>" algorithms abort
2229: the script then abort all these steps.</p>
1.81 ihickson 2230:
2231: </li>
2232:
1.155 ihickson 2233: </ol></li>
1.152 ihickson 2234:
1.327 ihickson 2235: </ol><h3 id="the-workernavigator-object"><span class="secno">5.2 </span>The <code><a href="#workernavigator">WorkerNavigator</a></code> object</h3>
2236:
2237: <p>The <dfn id="dom-worker-navigator" title="dom-worker-navigator"><code>navigator</code></dfn> attribute
1.357 ihickson 2238: of the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> interface must return an instance of
1.210 ihickson 2239: the <code><a href="#workernavigator">WorkerNavigator</a></code> interface, which represents the
1.327 ihickson 2240: identity and state of the user agent (the client):</p>
2241:
1.410 ihickson 2242: <pre class="idl">[Exposed=Worker]
2243: interface <dfn id="workernavigator">WorkerNavigator</dfn> {};
1.210 ihickson 2244: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorID</span>;
1.354 ihickson 2245: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorLanguage</span>;
1.327 ihickson 2246: <a href="#workernavigator">WorkerNavigator</a> implements <span>NavigatorOnLine</span>;</pre>
2247:
2248:
2249:
1.119 ihickson 2250:
1.412 ihickson 2251: <h3 id="worker-locations"><span class="secno">5.3 </span>Worker locations</h3>
1.327 ihickson 2252:
1.410 ihickson 2253: <pre class="idl">[Exposed=Worker]
2254: interface <dfn id="workerlocation">WorkerLocation</dfn> { };
1.365 ihickson 2255: <a href="#workerlocation">WorkerLocation</a> implements <span>URLUtilsReadOnly</span>;</pre>
1.327 ihickson 2256:
1.361 ihickson 2257: <p>A <code><a href="#workerlocation">WorkerLocation</a></code> object represents an <span>absolute URL</span> set at its
2258: creation.</p>
2259:
1.372 ihickson 2260: <p>The <code><a href="#workerlocation">WorkerLocation</a></code> interface supports the <code>URLUtilsReadOnly</code>
2261: interface. <a href="#refsURL">[URL]</a></p>
2262:
2263: <p>When the object is created, the user agent must invoke the element's
2264: <code>URLUtilsReadOnly</code> interface's <span title="concept-uu-set-the-input">set the
2265: input</span> algorithm with the <span>absolute URL</span> that the <code><a href="#workerlocation">WorkerLocation</a></code>
2266: object represents as the given value.</p>
1.327 ihickson 2267:
1.372 ihickson 2268: <p>The element's <code>URLUtilsReadOnly</code> interface's <span title="concept-uu-get-the-base">get the base</span> algorithm must return null.</p>
1.327 ihickson 2269:
2270:
2271:
2272: <h2 class="no-num" id="references">References</h2>
2273:
2274: <p>All references are normative unless marked "Non-normative".</p>
2275:
2276:
2277:
1.353 ihickson 2278: <dl><dt id="refsDOM">[DOM]</dt>
2279: <dd><cite><a href="http://dom.spec.whatwg.org/">DOM</a></cite>, A. van Kesteren, A. Gregor, Ms2ger. WHATWG.</dd>
1.153 ihickson 2280:
1.152 ihickson 2281: <dt id="refsECMA262">[ECMA262]</dt>
1.406 ihickson 2282: <dd><cite><a href="http://people.mozilla.org/~jorendorff/es6-draft.html">ECMAScript Language Specification</a></cite>. ECMA.</dd>
1.152 ihickson 2283:
1.415 ihickson 2284: <dt id="refsFILEAPI">[FILEAPI]</dt>
2285: <dd><cite><a href="http://dev.w3.org/2006/webapi/FileUpload/publish/FileAPI.html">File API</a></cite>, A. Ranganathan. W3C.</dd>
2286:
1.226 ihickson 2287: <dt id="refsHTML">[HTML]</dt>
1.416 ihickson 2288: <dd><cite><a href="//www.whatwg.org/specs/web-apps/current-work/">HTML</a></cite>, I. Hickson. WHATWG.</dd>
1.315 ihickson 2289:
1.154 ihickson 2290: <dt id="refsRFC2119">[RFC2119]</dt>
1.355 ihickson 2291: <dd><cite><a href="http://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF.</dd>
1.154 ihickson 2292:
1.365 ihickson 2293: <dt id="refsURL">[URL]</dt>
1.369 ihickson 2294: <dd><cite><a href="http://url.spec.whatwg.org/">URL</a></cite>, A. van Kesteren. WHATWG.</dd>
1.365 ihickson 2295:
1.154 ihickson 2296: <dt id="refsWEBIDL">[WEBIDL]</dt>
1.355 ihickson 2297: <dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web IDL</a></cite>, C. McCormack. W3C.</dd>
1.154 ihickson 2298:
1.327 ihickson 2299: </dl><h2 class="no-num" id="acknowledgements">Acknowledgements</h2> <!-- ACKS -->
2300:
2301: <p>Thanks to
1.81 ihickson 2302:
2303: Aaron Boodman,
1.388 ihickson 2304: Алексей Проскуряков (Alexey Proskuryakov),
1.81 ihickson 2305: Anne van Kesteren,
2306: Ben Turner,
2307: Dmitry Titov,
1.96 ihickson 2308: Drew Wilson,
1.97 ihickson 2309: Jeremy Orlow,
1.81 ihickson 2310: Jonas Sicking,
2311: Justin James,
2312: Kevin Hakanson,
2313: Maciej Stachowiak,
2314: Michael Nordman,
2315: Mike Smith,
2316:
2317: and
2318:
2319: Philip Taylor
2320:
1.327 ihickson 2321: for their useful and substantial comments.</p>
2322:
2323: <p>Huge thanks to the whole Gears team, who pioneered this
1.81 ihickson 2324: technology and whose experience has been a huge influence on this
1.327 ihickson 2325: specification.</p>
2326:
2327:
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