Annotation of html5/workers/Overview.html, revision 1.27
1.1 ihickson 1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
2: <!-- when publishing, change bits marked ZZZ -->
3:
4: <html lang=en-US-x-Hixie>
5: <head>
6: <title>Web Workers</title>
7: <link href="http://www.w3.org/StyleSheets/TR/%57%33%43-ED" rel=stylesheet
8: type="text/css">
9: <!-- ZZZ ED vs WD -->
10:
11: <body>
12: <div class=head>
13: <p><a href="http://www.w3.org/"><img alt=W3C height=48
14: src="http://www.w3.org/Icons/w3c_home" width=72></a></p>
15:
16: <h1 id=web-workers>Web Workers</h1>
17:
18: <h2 class="no-num no-toc" id=an-accompaniment>An accompaniment
19: specification for HTML5</h2>
20:
21: <h2 class="no-num no-toc" id=editors><!-- "W3C Working Draft" --> Editor's
1.26 ihickson 22: Draft <!--ZZZ--> 6 August 2008</h2>
1.1 ihickson 23:
24: <dl><!-- ZZZ: update the month/day
25: <dt>This Version:</dt>
26: <dd><a href="http://www.w3.org/TR/2008/WD-workers-20080101/">http://www.w3.org/TR/2008/WD-workers-20080101/</a></dd>
1.2 ihickson 27: <dt>Latest Published Version:</dt>
28: <dd><a href="http://www.w3.org/TR/workers/">http://www.w3.org/TR/workers/</a></dd>
1.1 ihickson 29: :ZZZ -->
30:
31: <dt>Latest Editor's Draft:
32:
33: <dd><a
34: href="http://dev.w3.org/html5/workers/">http://dev.w3.org/html5/workers/</a></dd>
1.2 ihickson 35: <!-- ZZZ: add the new version after it has shipped
36: <dt>Previous Versions:</dt>
37: <dd><a href="http://www.w3.org/TR/2008/WD-workers-20080101/">http://www.w3.org/TR/2008/WD-workers-20080101/</a>
38: :ZZZ -->
1.1 ihickson 39:
40: <dt>Editors:
41:
42: <dd><a href="mailto:ian@hixie.ch">Ian Hickson</a>, Google, Inc.
43: </dl>
44:
45: <p class=copyright><a
46: href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>
47: © 2008 <a href="http://www.w3.org/"><abbr title="World Wide Web
48: Consortium">W3C</abbr></a><sup>®</sup> (<a
49: href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
50: Technology">MIT</abbr></a>, <a href="http://www.ercim.org/"><abbr
51: title="European Research Consortium for Informatics and
52: Mathematics">ERCIM</abbr></a>, <a
53: href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
54: href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
55: <a
56: href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
57: and <a
58: href="http://www.w3.org/Consortium/Legal/copyright-documents">document
59: use</a> rules apply.</p>
60: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
61:
62: <p class="alt copyright">The <a
63: href="http://www.whatwg.org/specs/web-workers/current-work/">WHATWG
64: version</a> of this specification is available under a more permissive
65: license.</p>
66: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
67: </div>
68:
69: <hr>
70:
71: <h2 class="no-num no-toc" id=abstract>Abstract</h2>
72:
73: <p>This specification defines an API that allows Web application authors to
74: spawn background workers running scripts in parallel to their main page.
75: This allows for thread-like operation with message-passing as the
76: coordination mechanism.
77:
78: <h2 class="no-num no-toc" id=status>Status of this document</h2>
79: <!-- intro boilerplate (required) -->
80:
81: <p><em>This section describes the status of this document at the time of
82: its publication. Other documents may supersede this document. A list of
83: current W3C publications and the most recently formally published revision
84: of this technical report can be found in the <a
85: href="http://www.w3.org/TR/">W3C technical reports index</a> at
86: http://www.w3.org/TR/.</em></p>
87: <!-- where to send feedback (required) -->
88:
89: <p>If you wish to make comments regarding this document, please send them
90: to <a
91: href="mailto:public-html-comments@w3.org">public-html-comments@w3.org</a>
92: (<a
93: href="mailto:public-html-comments-request@w3.org?subject=subscribe">subscribe</a>,
94: <a
95: href="http://lists.w3.org/Archives/Public/public-html-comments/">archives</a>)
96: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
97: or <a href="mailto:whatwg@whatwg.org">whatwg@whatwg.org</a> (<a
98: href="http://lists.whatwg.org/listinfo.cgi/whatwg-whatwg.org">subscribe</a>,
99: <a
100: href="http://lists.whatwg.org/pipermail/whatwg-whatwg.org/">archives</a>).
101: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING SENTENCE TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
102: All feedback is welcome.</p>
103: <!-- stability (required) -->
104:
105: <p>Implementors should be aware that this specification is not stable.
106: <strong>Implementors who are not taking part in the discussions are likely
107: to find the specification changing out from under them in incompatible
108: ways.</strong> Vendors interested in implementing this specification
109: before it eventually reaches the Candidate Recommendation stage should
110: join the aforementioned mailing lists and take part in the discussions.</p>
111: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
112: <!-- version history or list of changes (required) -->
113:
114: <p>The latest stable version of the editor's draft of this specification is
115: always available on <a
116: href="http://dev.w3.org/html5/workers/Overview.html">the W3C CVS
117: server</a> and in the <a href="http://svn.whatwg.org/webworkers/">WHATWG
118: Subversion repository</a>. The latest editor's working copy (which may
119: contain unfinished text in the process of being prepared) is available <a
120: href="http://www.whatwg.org/specs/web-workers/current-work/">on the WHATWG
121: site</a>. Detailed change history can be obtained from the following
122: locations:</p>
123: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
124: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
125:
126: <ul>
127: <li>Twitter messages (non-editorial changes only): <a
128: href="http://twitter.com/WHATWG">http://twitter.com/WHATWG</a>
129:
130: <li>Interactive Web interface: <a
131: href="http://html5.org/tools/web-workers-tracker">http://html5.org/tools/web-workers-tracker</a>
132:
133: <li>Commit-Watchers mailing list: <a
134: href="http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org">http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a>
135:
136: <li>Subversion interface: <a
137: href="http://svn.whatwg.org/webworkers/">http://svn.whatwg.org/webworkers/</a>
138:
139: <li>CVS log: <a
140: href="http://dev.w3.org/cvsweb/html5/workers/Overview.html">http://dev.w3.org/cvsweb/html5/workers/Overview.html</a>
141: </ul>
142: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
143: <!-- status of document, group responsible (required) -->
144:
145: <p>The W3C <a href="http://www.w3.org/html/wg/">HTML Working Group</a> is
146: the W3C working group responsible for this specification's progress along
1.26 ihickson 147: the W3C Recommendation track. <!--ZZZ:--> This specification is the 6
1.25 ihickson 148: August 2008 <!--ZZZ "Working Draft"-->Editor's Draft. <!--:ZZZ--></p>
1.1 ihickson 149: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
150: <!-- relationship to other work (required) -->
151:
152: <p>This specification is also being produced by the <a
153: href="http://www.whatwg.org/">WHATWG</a>. The two specifications are
154: identical from the table of contents onwards.</p>
155: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
156: <!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
157: <!-- context and rationale (required) -->
158:
159: <p>This specification is intended to specify a part of the Web platform
160: closely related to HTML5. It is defined in a separate document primarily
161: to ease the cognitive load on reviewers.</p>
162: <!-- UNDER NO CIRCUMSTANCES IS THE FOLLOWING PARAGRAPH TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST -->
163: <!-- required patent boilerplate -->
164:
165: <p>This document was produced by a group operating under the <a
166: href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
167: 2004 W3C Patent Policy</a>. W3C maintains a <a
168: href="http://www.w3.org/2004/01/pp-impl/40318/status"
169: rel=disclosure>public list of any patent disclosures</a> made in
170: connection with the deliverables of the group; that page also includes
171: instructions for disclosing a patent. An individual who has actual
172: knowledge of a patent which the individual believes contains <a
173: href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
174: Claim(s)</a> must disclose the information in accordance with <a
175: href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
176: 6 of the W3C Patent Policy</a>.
177:
178: <h2 class="no-num no-toc" id=contents>Table of contents</h2>
179: <!--begin-toc-->
180:
181: <ul class=toc>
182: <li><a href="#introduction"><span class=secno>1. </span>Introduction</a>
183: <ul class=toc>
1.4 ihickson 184: <li><a href="#tutorial"><span class=secno>1.1 </span>Tutorial</a>
1.1 ihickson 185:
1.22 ihickson 186: <li><a href="#conformance"><span class=secno>1.2 </span>Conformance
1.1 ihickson 187: requirements</a>
188: <ul class=toc>
1.22 ihickson 189: <li><a href="#dependencies"><span class=secno>1.2.1
1.1 ihickson 190: </span>Dependencies</a>
191: </ul>
192:
1.22 ihickson 193: <li><a href="#terminology"><span class=secno>1.3 </span>Terminology</a>
1.4 ihickson 194: </ul>
195:
1.12 ihickson 196: <li><a href="#infrastructure"><span class=secno>2.
197: </span>Infrastructure</a>
1.4 ihickson 198: <ul class=toc>
1.26 ihickson 199: <li><a href="#the-workerglobalscope"><span class=secno>2.1 </span>The
200: <code>WorkerGlobalScope</code> interface</a>
1.4 ihickson 201:
1.15 ihickson 202: <li><a href="#base-urls"><span class=secno>2.2 </span>Base URLs and
203: origins of workers</a>
204:
205: <li><a href="#the-queue"><span class=secno>2.3 </span>The queue of
1.4 ihickson 206: events</a>
207:
1.15 ihickson 208: <li><a href="#the-workers"><span class=secno>2.4 </span>The worker's
1.9 ihickson 209: ports</a>
210:
1.15 ihickson 211: <li><a href="#processing"><span class=secno>2.5 </span>Processing
1.4 ihickson 212: model</a>
1.12 ihickson 213:
1.15 ihickson 214: <li><a href="#creating"><span class=secno>2.6 </span>Creating
1.12 ihickson 215: workers</a>
1.1 ihickson 216: </ul>
217:
1.12 ihickson 218: <li><a href="#apis-available"><span class=secno>3. </span>APIs available
219: to workers</a>
1.26 ihickson 220: <ul class=toc>
221: <li><a href="#importing"><span class=secno>3.1 </span>Importing scripts
222: and libraries</a>
223:
224: <li><a href="#apis-defined"><span class=secno>3.2 </span>APIs defined in
225: other specifications</a>
226:
227: <li><a href="#interface"><span class=secno>3.3 </span>Interface objects
228: and constructors</a>
229: </ul>
1.4 ihickson 230:
1.1 ihickson 231: <li class=no-num><a href="#references">References</a>
232:
233: <li class=no-num><a href="#acknowledgements">Acknowledgements</a>
234: </ul>
235: <!--end-toc-->
236:
237: <hr>
238:
239: <h2 id=introduction><span class=secno>1. </span>Introduction</h2>
240:
1.4 ihickson 241: <h3 id=tutorial><span class=secno>1.1 </span>Tutorial</h3>
1.1 ihickson 242:
243: <p><em>This section is non-normative.</em>
244:
1.4 ihickson 245: <p class=big-issue>This section is missing.
246:
1.22 ihickson 247: <h3 id=conformance><span class=secno>1.2 </span>Conformance requirements</h3>
1.1 ihickson 248:
249: <p>All diagrams, examples, and notes in this specification are
250: non-normative, as are all sections explicitly marked non-normative.
251: Everything else in this specification is normative.
252:
253: <p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
254: NOT",-->
255: "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the
256: normative parts of this document are to be interpreted as described in
257: RFC2119. For readability, these words do not appear in all uppercase
258: letters in this specification. <a href="#refsRFC2119">[RFC2119]</a></p>
259: <!-- XXX but they should be
260: marked up -->
261:
262: <p>Requirements phrased in the imperative as part of algorithms (such as
263: "strip any leading space characters" or "return false and abort these
264: steps") are to be interpreted with the meaning of the key word ("must",
265: "should", "may", etc) used in introducing the algorithm.
266:
267: <p>Some conformance requirements are phrased as requirements on attributes,
268: methods or objects. Such requirements are to be interpreted as
269: requirements on user agents.
270:
271: <p>Conformance requirements phrased as algorithms or specific steps may be
272: implemented in any manner, so long as the end result is equivalent. (In
273: particular, the algorithms defined in this specification are intended to
274: be easy to follow, and not intended to be performant.)
275:
276: <p>The only conformance class defined by this specification is user agents.
277:
278: <p>User agents may impose implementation-specific limits on otherwise
279: unconstrained inputs, e.g. to prevent denial of service attacks, to guard
280: against running out of memory, or to work around platform-specific
281: limitations.
282:
1.22 ihickson 283: <h4 id=dependencies><span class=secno>1.2.1 </span>Dependencies</h4>
1.1 ihickson 284:
285: <p>This specification relies on several other underlying specifications.
286:
287: <dl>
288: <dt>HTML5
289:
290: <dd>
291: <p>Many fundamental concepts from HTML5 are used by this specification.
292: <a href="#refsHTML5">[HTML5]</a></p>
293:
294: <dt>ECMAScript
295:
296: <dd>
297: <p>This specification is intended to be used with JavaScript as the
298: scripting language. <a href="#refsJS">[JS]</a></p>
299:
300: <dt>WebIDL
301:
302: <dd>
303: <p>The IDL blocks in this specification use the semantics of the WebIDL
304: specification. <a href="#refsWebIDL">[WebIDL]</a></p>
305: </dl>
306:
1.22 ihickson 307: <h3 id=terminology><span class=secno>1.3 </span>Terminology</h3>
1.1 ihickson 308:
309: <p>For simplicity, terms such as <em>shown</em>, <em>displayed</em>, and
310: <em>visible</em> might sometimes be used when referring to the way a
311: document is rendered to the user. These terms are not meant to imply a
312: visual medium; they must be considered to apply to other media in
313: equivalent ways.
314:
1.4 ihickson 315: <p>The construction "a <code title="">Foo</code> object", where <code
316: title="">Foo</code> is actually an interface, is sometimes used instead of
317: the more accurate "an object implementing the interface <code
318: title="">Foo</code>".
1.1 ihickson 319:
320: <p>The term DOM is used to refer to the API set made available to scripts
321: in Web applications, and does not necessarily imply the existence of an
322: actual <code>Document</code> object or of any other <code>Node</code>
323: objects as defined in the DOM Core specifications. <a
324: href="#refsDOM3CORE">[DOM3CORE]</a>
325:
326: <p>A DOM attribute is said to be <em>getting</em> when its value is being
327: retrieved (e.g. by author script), and is said to be <em>setting</em> when
328: a new value is assigned to it.
329:
330: <p>If a DOM object is said to be <dfn id=live>live</dfn>, then that means
331: that any attributes returning that object must always return the same
332: object (not a new object each time), and the attributes and methods on
333: that object must operate on the actual underlying data, not a snapshot of
334: the data.
335:
1.12 ihickson 336: <h2 id=infrastructure><span class=secno>2. </span>Infrastructure</h2>
1.4 ihickson 337:
1.26 ihickson 338: <h3 id=the-workerglobalscope><span class=secno>2.1 </span>The <code><a
339: href="#workerglobalscope">WorkerGlobalScope</a></code> interface</h3>
1.4 ihickson 340:
341: <pre
1.26 ihickson 342: class=idl>[NoInterfaceObject] interface <dfn id=workerglobalscope>WorkerGlobalScope</dfn> {
343: // core worker features
344: readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#self" title=dom-WorkerGlobalScope-self>self</a>;
345: readonly attribute DOMString <a href="#url" title=dom-WorkerGlobalScope-URL>URL</a>;
346: readonly attribute DOMString <a href="#name" title=dom-WorkerGlobalScope-name>name</a>;
347: readonly attribute boolean <a href="#closing" title=dom-WorkerGlobalScope-closing>closing</a>;
348: void <a href="#close" title=dom-WorkerGlobalScope-close>close</a>();
349:
350: // other APIs
351: readonly attribute WorkerUtils <a href="#utils" title=dom-WorkerGlobalScope-utils>utils</a>;
1.9 ihickson 352:
353: // event handler attributes
1.26 ihickson 354: attribute <span>EventListener</span> <a href="#onconnect" title=handler-WorkerGlobalScope-onconnect>onconnect</a>;
355: attribute <span>EventListener</span> <a href="#onunload" title=handler-WorkerGlobalScope-onunload>onunload</a>;
1.4 ihickson 356: };</pre>
357:
1.26 ihickson 358: <p>The <dfn id=self
359: title=dom-WorkerGlobalScope-self><code>self</code></dfn> attribute must
360: return the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
361: object itself.
1.9 ihickson 362:
1.26 ihickson 363: <p>The <dfn id=url title=dom-WorkerGlobalScope-URL><code>URL</code></dfn>
1.6 ihickson 364: attribute must return the value it was assigned when the <code><a
1.26 ihickson 365: href="#workerglobalscope">WorkerGlobalScope</a></code> object was created
366: by the "<a href="#run-a">run a worker</a>" algorithm. It gives the
367: <span>absolute URL</span> of the script that was used to initialize the
368: worker.
369:
370: <p>The <dfn id=name
371: title=dom-WorkerGlobalScope-name><code>name</code></dfn> attribute must
372: return the value it was assigned when the <code><a
373: href="#workerglobalscope">WorkerGlobalScope</a></code> object was created
374: by the "<a href="#run-a">run a worker</a>" algorithm. If it has a value
375: that isn't the empty string, its value represents the name that can be
376: used to obtain a reference to the worker using the <code
377: title=dom-WorkerFactory-createNamedWorker><a
1.11 ihickson 378: href="#createnamedworker">createNamedWorker()</a></code> method.
1.6 ihickson 379:
1.4 ihickson 380: <p>The <dfn id=closing
1.26 ihickson 381: title=dom-WorkerGlobalScope-closing><code>closing</code></dfn> attribute
382: must return false until it is set to true by one of the algorithms in the
1.19 ihickson 383: processing model section below.
1.4 ihickson 384:
1.9 ihickson 385: <p>The following are the <span>event handler DOM attributes</span> that
386: must be supported by objects implementing the <code><a
1.26 ihickson 387: href="#workerglobalscope">WorkerGlobalScope</a></code> interface:
1.9 ihickson 388:
389: <dl>
1.20 ihickson 390: <dt><dfn id=onconnect
1.26 ihickson 391: title=handler-WorkerGlobalScope-onconnect><code>onconnect</code></dfn>
1.9 ihickson 392:
393: <dd>
394: <p>Must be invoked whenever a <code
1.26 ihickson 395: title=event-WorkerGlobalScope-connect>connect</code> event is targeted
396: at or bubbles through the <code><a
397: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.9 ihickson 398:
399: <dt><dfn id=onunload
1.26 ihickson 400: title=handler-WorkerGlobalScope-onunload><code>onunload</code></dfn>
1.9 ihickson 401:
402: <dd>
403: <p>Must be invoked whenever a <code title=event-unload>unload</code>
404: event is targeted at or bubbles through the <code><a
1.26 ihickson 405: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.9 ihickson 406: </dl>
407:
1.26 ihickson 408: <p>The <dfn id=utils
409: title=dom-WorkerGlobalScope-utils><code>utils</code></dfn> attribute must
410: return the <code><a href="#workerutils">WorkerUtils</a></code> object
411: created for the <code><a
412: href="#workerglobalscope">WorkerGlobalScope</a></code> object when the
413: worker was created.
414:
1.15 ihickson 415: <h3 id=base-urls><span class=secno>2.2 </span>Base URLs and origins of
416: workers</h3>
417:
418: <p>The <span>base URL</span> of a <span>URL</span> passed to an API in a
1.16 ihickson 419: worker is the <span>absolute URL</span> given by the value of the <code
1.26 ihickson 420: title=dom-WorkerGlobalScope-URL><a href="#url">URL</a></code> attribute of
421: the worker's <code><a
422: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.15 ihickson 423:
1.25 ihickson 424: <p>Both the <span>origin</span> and <span>effective script origin</span> of
425: scripts running in workers are the <span>origin</span> of the
1.16 ihickson 426: <span>absolute URL</span> given by the value of the <code
1.26 ihickson 427: title=dom-WorkerGlobalScope-URL><a href="#url">URL</a></code> attribute of
428: the worker's <code><a
429: href="#workerglobalscope">WorkerGlobalScope</a></code> object.
1.15 ihickson 430:
431: <h3 id=the-queue><span class=secno>2.3 </span>The queue of events</h3>
1.4 ihickson 432:
1.26 ihickson 433: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
434: object is asssociated with a <dfn id=queue>queue of events</dfn>, which is
435: initially empty.
1.4 ihickson 436:
437: <p>An event in the queue can be a DOM event or a timeout callback.
438:
1.8 ihickson 439: <p>All asynchronous callbacks and events that would be called or dispatched
440: in the worker must be added to the worker's queue, with the "<a
441: href="#run-a">run a worker</a>" processing model below taking care of
442: actually calling the callbacks or dispatching the events.
443:
1.26 ihickson 444: <p>Once the <code><a
445: href="#workerglobalscope">WorkerGlobalScope</a></code>'s <code
446: title=dom-WorkerGlobalScope-closing><a href="#closing">closing</a></code>
1.8 ihickson 447: attribute is set to true, the queue must discard anything else that would
448: be added to it. Effectively, once the <code
1.26 ihickson 449: title=dom-WorkerGlobalScope-closing><a href="#closing">closing</a></code>
1.8 ihickson 450: attribute is true, timers stop firing, notifications for all pending
451: asynchronous operations are dropped, etc.
452:
1.15 ihickson 453: <h3 id=the-workers><span class=secno>2.4 </span>The worker's ports</h3>
1.9 ihickson 454:
455: <p>Workers communicate with other workers and with <span title="browsing
456: context">browsing contexts</span> through <span title="channel
457: messaging">message channels</span> and their <code>MessagePort</code>
458: objects.
459:
1.26 ihickson 460: <p>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
461: <var title="">worker</var> has a list of <dfn id=the-workers0>the worker's
1.9 ihickson 462: ports</dfn>, which consists of all the <code>MessagePort</code> objects
463: that are entangled with another port and that have one (but only one) port
1.26 ihickson 464: owned by <var title="">worker</var>. This list includes all the
465: <code>MessagePort</code> objects that are in events pending in the <a
466: href="#queue">queue of events</a>.
1.9 ihickson 467:
1.17 ihickson 468: <hr>
469:
470: <p>A worker is said to be a <dfn id=front-line>front-line worker</dfn> if
471: at least one of the <a href="#the-workers0">the worker's ports</a> has an
1.26 ihickson 472: entangled <code>MessagePort</code> owned by a <code>Window</code> object.
1.17 ihickson 473:
474: <p>A worker is said to be a <dfn id=needed>needed worker</dfn> if either:
475:
476: <ul>
477: <li>it is a <a href="#front-line">front-line worker</a>, or
478:
479: <li>at least one of the <a href="#the-workers0">the worker's ports</a> has
1.26 ihickson 480: an entangled <code>MessagePort</code> owned by a <code><a
481: href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
482: itself a <a href="#needed">needed worker</a>.
1.17 ihickson 483: </ul>
484:
485: <hr>
486:
487: <p>A worker is said to be an <dfn id=active>active front-line worker</dfn>
488: if at least one of the <a href="#the-workers0">the worker's ports</a> has
489: both an <code title=dom-MessagePort-active>active</code> attribute whose
1.26 ihickson 490: value is true and an entangled <code>MessagePort</code> whose owner is a
491: <code>Window</code> object.
1.17 ihickson 492:
493: <p>A worker is said to be an <dfn id=active0>active needed worker</dfn> if
494: either:
495:
496: <ul>
497: <li>it is an <a href="#active">active front-line worker</a>, or
498:
499: <li>at least one of the <a href="#the-workers0">the worker's ports</a> has
1.26 ihickson 500: an entangled <code>MessagePort</code> owned by a <code><a
501: href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
502: itself an <a href="#active0">active needed worker</a>.
1.17 ihickson 503: </ul>
504:
1.15 ihickson 505: <h3 id=processing><span class=secno>2.5 </span>Processing model</h3>
1.4 ihickson 506:
1.6 ihickson 507: <p>When a user agent is to <dfn id=run-a>run a worker</dfn> named <var
1.7 ihickson 508: title="">name</var> for a script with <span>URL</span> <var
509: title="">url</var>, a browsing context <var title="">owner browsing
510: context</var> and a <code>Document</code> <var title="">owner
511: document</var>, it must run the following steps in a completely separate
512: and parallel execution environment:
1.4 ihickson 513:
514: <ol>
515: <li>
1.7 ihickson 516: <p>Attempt to <span>fetch</span><!-- XXX --> the resource identified by
517: <var title="">url</var>.</p>
518:
519: <p>If the attempt fails, then abort these steps and invoke the <a
1.9 ihickson 520: href="#worker" title="worker creation failed">error handling steps</a>
1.7 ihickson 521: defined by the algorithm that called this one.</p>
522:
523: <p>If the attempt succeeds, then let <var title="">script</var> be the
524: resource that was obtained.</p>
525:
526: <p class=note>As with <code>script</code> elements, the MIME type of the
527: script is ignored. Unlike with <code>script</code> elements, there is no
528: way to override the type. It's always assumed to be JavaScript.</p>
529: <!-- XXX people will complain about
530: this. I guess we might want to examine the MIME type... -->
531:
532:
533: <li>
1.26 ihickson 534: <p>Create a new <code><a
535: href="#workerglobalscope">WorkerGlobalScope</a></code> object, <var
536: title="">worker</var>.</p>
1.4 ihickson 537:
538: <li>
1.26 ihickson 539: <p>Set the <code title=dom-WorkerGlobalScope-URL><a
540: href="#url">URL</a></code> attribute of <var title="">worker</var> to
541: the value of <var title="">url</var>.</p>
1.9 ihickson 542:
543: <li>
1.26 ihickson 544: <p>Set the <code title=dom-WorkerGlobalScope-name><a
1.19 ihickson 545: href="#name">name</a></code> attribute of <var title="">worker</var> to
1.6 ihickson 546: the value of <var title="">name</var>.</p>
547:
548: <li>
1.26 ihickson 549: <p>Create a new <code><a href="#workerutils">WorkerUtils</a></code>
550: object for the <code title=dom-WorkerGlobalScope-utils><a
551: href="#utils">utils</a></code> attribute of <var title="">worker</var>.
552:
553: <li>
1.4 ihickson 554: <p>Let <var title="">script</var>'s <span>script execution context</span>
555: (and thus also <span>global object</span>) be <var
1.19 ihickson 556: title="">worker</var>.</p>
1.4 ihickson 557:
558: <li>
559: <p>Let <var title="">script</var>'s <span>script browsing context</span>
560: be <var title="">owner browsing context</var>.</p>
561:
562: <li>
563: <p>Let <var title="">script</var>'s <span>script document context</span>
564: be <var title="">owner document</var>.</p>
565:
566: <li>
1.9 ihickson 567: <p>Invoke the <a href="#success" title="worker creation
568: succeeded">success steps</a> defined by the algorithm that called this
1.17 ihickson 569: one.</p>
570:
571: <p class=note>This will usually add an event to the <a
572: href="#queue">queue of events</a>. If it does, that event will have a
573: <code>MessagePort</code> and thus the list of <a
574: href="#the-workers0">the worker's ports</a> will not be empty. If it
1.19 ihickson 575: doesn't, then the next step will set the <var title="">worker</var>
1.26 ihickson 576: object's <code title=dom-WorkerGlobalScope-closing><a
1.17 ihickson 577: href="#closing">closing</a></code> attribute to true.</p>
578:
579: <li>
580: <p>Start monitoring <var title="">worker</var>, such that as soon as the
581: worker stops being a <a href="#needed">needed worker</a>, the <var
1.26 ihickson 582: title="">worker</var> object's <code
583: title=dom-WorkerGlobalScope-closing><a
1.17 ihickson 584: href="#closing">closing</a></code> attribute is set to true.</p>
1.9 ihickson 585:
586: <li>
587: <p>Start monitoring <var title="">worker</var>, such that whenever the
1.19 ihickson 588: <var title="">worker</var> object's <code
1.26 ihickson 589: title=dom-WorkerGlobalScope-closing><a
590: href="#closing">closing</a></code> attribute is false and the worker is
591: not an <a href="#active0">active needed worker</a>, the user agent
592: suspends execution of script in that worker until such time as either
593: the <code title=dom-WorkerGlobalScope-closing><a
594: href="#closing">closing</a></code> attribute switches to true or the
595: worker becomes an <a href="#active0">active needed worker</a>.</p>
1.7 ihickson 596:
597: <li>
598: <p>Run <var title="">script</var> until it either returns, fails to catch
599: an exception, or gets prematurely aborted by the "<a href="#kill-a">kill
600: a worker</a>" algorithm below.</p>
601:
602: <p class=note>If the script gets aborted by the "<a href="#kill-a">kill a
603: worker</a>" algorithm, then that same algorithm will cause there to only
604: be a single event in the <a href="#queue">queue of events</a> at the
1.9 ihickson 605: next step, namely the <code title=message-unload>unload</code> event.
606: However, if the event is ignored then it will become true as soon as
607: that port is garbage collected.</p>
1.4 ihickson 608:
609: <li>
1.9 ihickson 610: <p><i>Event loop</i>: Wait until either there is an event in the <a
1.4 ihickson 611: href="#queue">queue of events</a> associated with <var
1.19 ihickson 612: title="">worker</var> or the <var title="">worker</var> object's <code
1.26 ihickson 613: title=dom-WorkerGlobalScope-closing><a
614: href="#closing">closing</a></code> attribute is set to true.</p>
1.4 ihickson 615:
616: <li>
617: <p>Dispatch the oldest event or callback in the <a href="#queue">queue of
1.9 ihickson 618: events</a>, if any. The handling of this event or the execution of this
619: callback might get prematurely aborted by the "<a href="#kill-a">kill a
1.8 ihickson 620: worker</a>" algorithm below.</p>
1.4 ihickson 621:
622: <li>
623: <p>If there are any more events in the <a href="#queue">queue of
1.19 ihickson 624: events</a> or if the <var title="">worker</var> object's <code
1.26 ihickson 625: title=dom-WorkerGlobalScope-closing><a
626: href="#closing">closing</a></code> attribute is set to false, then jump
627: back to the step above labeled <i>event loop</i>.</p>
1.4 ihickson 628:
629: <li>
630: <p class=big-issue>timers, intervals, XMLHttpRequests, database
631: transactions, etc, must be killed; ports must be deactivated and
1.8 ihickson 632: unentangled (do not send unload)</p>
1.4 ihickson 633: </ol>
634:
635: <hr>
636:
637: <p>When a user agent is to <dfn id=kill-a>kill a worker</dfn>, it must run
638: the following steps in parallel with the worker's main loop (the "<a
639: href="#run-a">run a worker</a>" processing model defined above):
640:
641: <ol>
642: <li>
643: <p>Create an <code>Event</code> object with the event name <code
644: title=event-unload>unload</code>, which does not bubble and is not
645: cancelable, and add it to the worker's <code><a
1.26 ihickson 646: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.8 ihickson 647: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 648: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.4 ihickson 649:
650: <li>
1.26 ihickson 651: <p>Set the worker's <code><a
652: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code
653: title=dom-WorkerGlobalScope-closing><a
1.8 ihickson 654: href="#closing">closing</a></code> attribute to true.
655:
656: <li>
657: <p>Wait a user-agent-defined amount of time. If the "<a href="#run-a">run
658: a worker</a>" processing model defined above immediately starts running
659: event listeners registered for <code title=event-unload>unload</code>
660: event, this time should not be zero — the idea is that the <code
661: title=event-unload>unload</code> event can be used to clean up when
662: shutting down unexpectedly.
1.4 ihickson 663:
664: <li>
665: <p>If there are any events in the <a href="#queue">queue of events</a>
666: other than the <code title=event-unload>unload</code> event that this
667: algorithm just added, discard them without dispatching them.
668:
669: <li>
670: <p>If the <code title=event-unload>unload</code> event that this
671: algorithm just added hasn't yet been dispatched, then abort the script
672: currently running in the worker.
673:
674: <li>
675: <p>Wait a user-agent-defined amount of time.
676:
677: <li>
678: <p>Abort the script currently running in the worker (if any script is
679: running, then it will be a handler for the <code
680: title=event-unload>unload</code> event).
681: </ol>
682:
1.19 ihickson 683: <p>User agents may invoke the "<a href="#kill-a">kill a worker</a>"
684: processing model on a worker at any time, e.g. in response to user
685: requests, in response to CPU quota management, or when a worker stops
686: being a <a href="#needed">needed worker</a> if the worker continues
1.26 ihickson 687: executing even after its <code title=dom-WorkerGlobalScope-closing><a
1.19 ihickson 688: href="#closing">closing</a></code> attribute was set to true.
689:
1.8 ihickson 690: <hr>
691:
692: <p>When a script invokes the <dfn id=close
1.26 ihickson 693: title=dom-WorkerGlobalScope-close><code>close()</code></dfn> method on a
694: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object,
695: the user agent must run the following steps:
1.8 ihickson 696:
697: <ol>
698: <li>
699: <p>Create an <code>Event</code> object with the event name <code
700: title=event-unload>unload</code>, which does not bubble and is not
701: cancelable, and add it to the <code><a
1.26 ihickson 702: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.8 ihickson 703: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 704: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.8 ihickson 705:
706: <li>
1.26 ihickson 707: <p>Set the worker's <code><a
708: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <code
709: title=dom-WorkerGlobalScope-closing><a
1.8 ihickson 710: href="#closing">closing</a></code> attribute to true.
711:
712: <li>
713: <p>For each <code>MessagePort</code> object that is entangled with
1.26 ihickson 714: another port and that has one (but only one) port whose owner is the
715: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
716: on which the method was invoked, run the following substeps:</p>
1.8 ihickson 717:
718: <ol>
719: <li>
720: <p>Unentangle the two ports.
721:
722: <li>
1.9 ihickson 723: <p>Set both ports' <code title=dom-MessagePort-active>active</code>
1.8 ihickson 724: attribute to false.
725:
726: <li>
727: <p>At the next available opportunity, after any scripts have finished
728: executing<!-- XXX queue -->, <span>fire a simple event</span> called
729: <code title=event-unload>unload</code> at the other port (the one
1.26 ihickson 730: whose owner is not the <code><a
731: href="#workerglobalscope">WorkerGlobalScope</a></code> object on which
732: the <code title=dom-WorkerGlobalScope-close><a
1.8 ihickson 733: href="#close">close()</a></code> method was called).
734: </ol>
735: </ol>
736:
1.15 ihickson 737: <h3 id=creating><span class=secno>2.6 </span>Creating workers</h3>
1.5 ihickson 738:
739: <pre
1.26 ihickson 740: class=idl>[NoInterfaceObject] interface <dfn id=workerfactory>WorkerFactory</dfn> {
741: <span>MessagePort</span> <a href="#createworker" title=dom-WorkerFactory-createWorker>createWorker</a>(in DOMString scriptURL);
742: <span>MessagePort</span> <a href="#createnamedworker" title=dom-WorkerFactory-createNamedWorker>createNamedWorker</a>(in DOMString name, in DOMString scriptURL);
1.5 ihickson 743: };</pre>
744:
1.26 ihickson 745: <p>Objects that implement the <code>Window</code> and <code><a
746: href="#workerutils">WorkerUtils</a></code> interfaces must also implement
747: the <code><a href="#workerfactory">WorkerFactory</a></code> interface.
1.5 ihickson 748:
1.9 ihickson 749: <hr>
750:
1.11 ihickson 751: <p>When the <dfn id=createworker
1.26 ihickson 752: title=dom-WorkerFactory-createWorker><code>createWorker(<var
1.11 ihickson 753: title="">scriptURL</var>)</code></dfn> method is invoked, the user agent
754: must run the following steps:
1.9 ihickson 755:
756: <ol>
757: <li>
758: <p><span title="resolve a url">Resolve</span> the <var
759: title="">scriptURL</var> argument.
760:
761: <li>
762: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
763:
764: <li>
765: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
766: is not the <span title="same origin">same</span> as the origin of the
767: script that invoked the method, then throw a <span>security
768: exception</span>.
769:
770: <li>
771: <p><a href="#create">Create a worker</a> from the resulting
772: <span>absolute URL</span> whose name is the empty string.
773:
774: <li>
775: <p>Return the <code>MessagePort</code> object returned from the <a
776: href="#create">create a worker</a> algorithm.
777: </ol>
778:
779: <hr>
780:
1.11 ihickson 781: <p>When the <dfn id=createnamedworker
1.26 ihickson 782: title=dom-WorkerFactory-createNamedWorker><code>createNamedWorker(<var
1.11 ihickson 783: title="">name</var>, <var title="">scriptURL</var>)</code></dfn> method is
1.9 ihickson 784: invoked, the user agent must run the following steps:
785:
786: <ol>
787: <li>
788: <p><span title="resolve a url">Resolve</span> the <var
789: title="">scriptURL</var> argument.
1.4 ihickson 790:
1.9 ihickson 791: <li>
792: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
793:
794: <li>
795: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
796: is not the <span title="same origin">same</span> as the origin of the
797: script that invoked the method, then throw a <span>security
798: exception</span>.
799:
800: <li>
801: <p>If the <var title="">name</var> argument is the empty string, <a
802: href="#create">create a worker</a> from the resulting <span>absolute
803: URL</span>, whose name is the empty string, and return the
804: <code>MessagePort</code> object returned from the <a
805: href="#create">create a worker</a> algorithm. Then, abort these steps.
806:
807: <li>
1.26 ihickson 808: <p>If there exists a worker whose <code
809: title=dom-WorkerGlobalScope-closing><a
1.9 ihickson 810: href="#closing">closing</a></code> attribute is false, whose <code
1.26 ihickson 811: title=dom-WorkerGlobalScope-name><a href="#name">name</a></code>
812: attribute is exactly equal to the <var title="">name</var> argument, and
813: whose <code title=dom-WorkerGlobalScope-URL><a
814: href="#url">URL</a></code> attribute has the <span>same origin</span> as
815: the resulting <span>absolute URL</span>, then run these substeps:</p>
1.9 ihickson 816:
817: <ol>
818: <li>
1.26 ihickson 819: <p>If that worker's <code title=dom-WorkerGlobalScope-URL><a
1.9 ihickson 820: href="#url">URL</a></code> attribute is not exactly equal to the
821: resulting <span>absolute URL</span>, then throw a
822: <code>URL_MISMATCH_ERR</code> exception and abort these steps. <span
823: class=big-issue>code 19</span>
824:
825: <li>
826: <p><span>Create a new <code>MessagePort</code> object</span> owned by
827: the <span>script execution context</span> of the script that invoked
828: the method.
829:
830: <li>
831: <p>Return that port.
832:
833: <li>
1.20 ihickson 834: <p>Asynchronously, <a href="#connect" title="connect to a
835: worker">connect</a> to this preexisting worker, with the newly created
1.9 ihickson 836: port.
837: </ol>
838:
839: <p>Otherwise, <a href="#create">create a worker</a> from the resulting
840: <span>absolute URL</span>, whose name is the value of the <var
841: title="">name</var> argument, and return the <code>MessagePort</code>
842: object returned from the <a href="#create">create a worker</a>
843: algorithm.</p>
844: </ol>
845:
846: <hr>
847:
848: <p>The steps to <dfn id=create>create a worker</dfn> from a
849: <span>URL</span> <var title="">url</var> and whose name is <var
850: title="">name</var>, in the context of a method call, are as follows:
851:
852: <ol>
853: <li>
854: <p><span>Create a new <code>MessagePort</code> object</span> owned by the
855: <span>script execution context</span> of the script that invoked the
856: method.
857:
858: <li>
859: <p>Return that port.
860:
861: <li>
862: <p>In a parallel execution context (i.e. a separate thread or process or
863: equivalent construct), <a href="#run-a">run a worker</a> named <var
864: title="">name</var> for the script with <span>URL</span> <var
865: title="">url</var>, with the <span>script browsing context</span> of the
866: script that invoked the method as the <var title="">owner browsing
867: context</var> and with the <span>script document context</span> of the
868: script that invoked the method as the <var title="">owner
869: document</var>.</p>
870:
871: <p>If that algorithm invokes the steps for <dfn id=success title="worker
1.20 ihickson 872: creation succeeded">success steps</dfn>, then <a href="#connect"
873: title="connect to a worker">connect</a> to this new worker, with the
874: newly created port.</p>
1.9 ihickson 875:
876: <p>Otherwise, if the <dfn id=worker>worker creation failed</dfn>, then at
877: the next available opportunity, after any scripts have finished
878: executing<!-- XXX queue -->, <span>fire a simple event</span> called
879: <code title=event-error>error</code> at the newly created port.</p>
880: </ol>
881:
882: <hr>
883:
1.20 ihickson 884: <p>The steps to <dfn id=connect>connect to a worker</dfn> given a
1.9 ihickson 885: <code>MessagePort</code> object <var title="">port</var> are as follows:
886:
887: <ol>
888: <li>
889: <p>If <var title="">port</var> would have been garbage collected, or if
1.26 ihickson 890: the <span>active document</span> of the owner of <var
1.9 ihickson 891: title="">port</var> is no longer the same <code>Document</code> object
892: as when <var title="">port</var> was created, then do nothing. Abort
893: these steps. If the worker was just created, it'll get killed
894: immediately.</p>
895:
896: <li>
897: <p><span>Create a new <code>MessagePort</code> object</span> owned by the
1.26 ihickson 898: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> of the
899: worker.
1.9 ihickson 900:
901: <li>
902: <p><span>Entangle</span> this newly created port and the port <var
903: title="">port</var> that was passed to these steps.
904:
905: <li>
906: <p>Set the <code title=dom-MessagePort-active>active</code> attribute of
907: both ports to true.
908:
909: <li>
910: <p>At the next available opportunity, after any scripts have finished
911: executing<!-- XXX queue -->, <span>fire a simple event</span> called
912: <code title=event-load>load</code> at <var title="">port</var>.
913:
914: <li>
915: <p>Create an event that uses the <code>MessageEvent</code> interface,
1.20 ihickson 916: with the name <code title=event-connect>connect</code>, which does not
1.9 ihickson 917: bubble, is cancelable, has no default action, has a <code
918: title=dom-MessageEvent-data>data</code> attribute whose value is the
919: empty string and has a <code
920: title=dom-MessageEvent-messagePort>messagePort</code> attribute whose
921: value is the newly created port, and add it to the worker's <code><a
1.26 ihickson 922: href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
1.9 ihickson 923: href="#queue">queue of events</a>, targetted at the <code><a
1.26 ihickson 924: href="#workerglobalscope">WorkerGlobalScope</a></code> object itself.
1.9 ihickson 925: </ol>
1.7 ihickson 926:
1.12 ihickson 927: <h2 id=apis-available><span class=secno>3. </span>APIs available to workers</h2>
928:
1.26 ihickson 929: <pre
930: class=idl>[NoInterfaceObject] interface <dfn id=workerutils>WorkerUtils</dfn> {
1.27 ! ihickson 931: boolean <a href="#importscript" title=dom-WorkerGlobalScope-importScript>importScript</a>(in DOMString url);
1.26 ihickson 932: readonly attribute <span>Storage</span> <a href="#localstorage" title=dom-localStorage>localStorage</a>;
933: <span>Database</span> <a href="#opendatabase" title=dom-opendatabase>openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize);
934: void <a href="#shownotification" title=dom-showNotification>showNotification</a>(in DOMString title, in DOMString subtitle, in DOMString description);
935: void <a href="#shownotification" title=dom-showNotification>showNotification</a>(in DOMString title, in DOMString subtitle, in DOMString description, in VoidCallback onclick);
936: };</pre>
1.18 ihickson 937:
1.12 ihickson 938: <p>Objects that implement the <code><a
1.26 ihickson 939: href="#workerutils">WorkerUtils</a></code> interface must also implement
1.12 ihickson 940: the following interfaces:
941:
942: <ul>
1.26 ihickson 943: <li>The <code>WindowTimers</code> interface
1.12 ihickson 944:
1.26 ihickson 945: <li>The <code>EventTarget</code> interface
1.12 ihickson 946:
1.26 ihickson 947: <li>The <code><a href="#workerfactory">WorkerFactory</a></code> interface,
948: as noted earlier in this specification
1.12 ihickson 949: </ul>
950:
1.23 ihickson 951: <p class=big-issue>Need to define a sync database API.
952:
953: <p class=big-issue>May need to define a browser sniffing API (like
954: window.navigator).</p>
1.18 ihickson 955: <!-- XXX ApplicationCache -->
956: <!-- XXX a way to set cookies on the URL for the script -->
1.24 ihickson 957: <!-- XXX debugging: void log(in DOMString s); // log to console -->
958: <!-- XXX debugging: onerror -->
1.13 ihickson 959:
1.18 ihickson 960: <hr>
1.13 ihickson 961:
1.18 ihickson 962: <p>The DOM APIs (<code>Node</code> objects, <code>Document</code> objects,
963: etc) are not available to workers in this version of this specification.
1.13 ihickson 964:
1.26 ihickson 965: <h3 id=importing><span class=secno>3.1 </span>Importing scripts and
966: libraries</h3>
967:
1.27 ! ihickson 968: <p>When a script invokes the <dfn id=importscript
! 969: title=dom-WorkerGlobalScope-importScript><code>importScript(<var
1.26 ihickson 970: title="">url</var>)</code></dfn> method on a <code><a
971: href="#workerglobalscope">WorkerGlobalScope</a></code> object, the user
972: agent must run the following steps:
973:
974: <ol>
975: <li>
976: <p><span title="resolve a url">Resolve</span> the <var title="">url</var>
977: argument.
978:
979: <li>
980: <p>If this fails, throw a <code>SYNTAX_ERR</code> exception.
981:
982: <li>
983: <p>If the <span>origin</span> of the resulting <span>absolute URL</span>
984: is not the <span title="same origin">same</span> as the origin of the
985: script that invoked the method, then throw a <span>security
986: exception</span>.
987:
988: <li>
989: <p>Attempt to <span>fetch</span><!-- XXX --> the resource identified by
990: the resulting <span>absolute URL</span>.</p>
991:
992: <p>If the attempt fails, return false and abort these steps.</p>
993:
994: <p>If the attempt succeeds, then let <var title="">script</var> be the
995: resource that was obtained.</p>
996:
997: <p class=note>As with the initial script, the script here is always
998: assumed to be JavaScript, regardless of the MIME type.</p>
999: <!-- XXX -->
1000:
1001: <li>
1002: <p>Let <var title="">script</var>'s <span>script execution
1003: context</span>, <span>script browsing context</span>, and <span>script
1004: document context</span> be the same as for the script that was executed
1005: by the <a href="#run-a">run a worker</a> processing model for this
1006: worker.</p>
1007:
1008: <li>
1009: <p>Run <var title="">script</var> until it either returns, fails to catch
1010: an exception, or gets prematurely aborted by the "<a href="#kill-a">kill
1011: a worker</a>" algorithm above.</p>
1012:
1013: <p>If an exception was raised or if the script was prematurely aborted,
1014: then abort these steps, letting the exception or aborting continue to be
1015: processed by the script that called the <code
1.27 ! ihickson 1016: title=dom-WorkerGlobalScope-importScript><a
! 1017: href="#importscript">importScript()</a></code> method.</p>
1.26 ihickson 1018:
1019: <p>Otherwise, return true.</p>
1020: </ol>
1021:
1022: <h3 id=apis-defined><span class=secno>3.2 </span>APIs defined in other
1023: specifications</h3>
1024:
1.27 ! ihickson 1025: <p>The <dfn id=localstorage
1.26 ihickson 1026: title=dom-localStorage><code>localStorage</code></dfn>, <dfn
1027: id=opendatabase title=dom-opendatabase><code>openDatabase()</code></dfn>
1028: must act as defined for the APIs with the same names on the
1029: <code>Window</code> object in the HTML5 specification, with the exception
1030: that where the API would use the <span>origin</span> of the <span>active
1031: document</span> of the <span>browsing context</span> of the
1032: <code>Window</code> object on which the method was supposedly invoked, it
1033: must instead use the <span>origin</span> of the script that invoked the
1034: method. <a href="#refsHTML5">[HTML5]</a>
1035:
1036: <p>The <dfn id=shownotification
1037: title=dom-showNotification><code>showNotification()</code></dfn> methods
1038: must act as defined for the APIs with the same names on the
1039: <code>Window</code> object in the HTML5 specification. <a
1040: href="#refsHTML5">[HTML5]</a>
1041:
1042: <h3 id=interface><span class=secno>3.3 </span>Interface objects and
1043: constructors</h3>
1044:
1045: <p>There must be no interface objects and constructors available in the
1046: global scope of scripts whose <span>script execution context</span> is a
1047: <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
1048: except for the following:
1049:
1050: <ul>
1051: <li>
1052: <p><code>XMLHttpRequest</code> and all interface objects and constructors
1053: defined by the XMLHttpRequest specifications, except that the
1054: <span>document response entity body</span> must always be null. <a
1055: href="#refsXHR">[XHR]</a>
1056:
1057: <li>
1058: <p>The <code>WebSocket</code> interface object and constructor.
1059:
1060: <li>
1061: <p>The <code>MessageChannel</code> interface object and constructor.
1062: </ul>
1063:
1.1 ihickson 1064: <h2 class=no-num id=references>References</h2>
1065:
1066: <p class=big-issue>This section will be written in a future
1067: draft.<!--XXX-->
1068:
1069: <h2 class=no-num id=acknowledgements>Acknowledgements</h2>
1070: <!-- ACKS -->
1071:
1.26 ihickson 1072: <p>Thanks to Aaron Boodman, Jonas Sicking, Maciej Stachowiak, Mike Smith,
1073: and Philip Taylor for their useful and substantial comments.
1.4 ihickson 1074:
1075: <p>Huge thanks to the whole Gears team, who pioneered this technology and
1076: whose experience has been a huge influence on this specification.
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