discovery-api/Overview.src.html
author Rich Tibbett <richt@opera.com>
Wed, 22 Aug 2012 16:39:44 +0200
changeset 194 ad608906c611
parent 192 3ecf12df315d
child 195 76074ec7e535
permissions -rw-r--r--
Minor editorial to Networked Service Discovery
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<!DOCTYPE html>
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<html>
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  <head>
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    <title>Networked Service Discovery and Messaging</title>
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    <meta http-equiv='Content-Type' content='text/html;charset=utf-8'/>
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    <script type="text/javascript" class='remove'>
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          specStatus:   "ED",
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          //publishDate:  "2012-08-22",
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          shortName:    "discovery-api",
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          edDraftURI:   "http://w3c-test.org/dap/discovery-api/",
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          previousMaturity: "WD",
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          previousPublishDate: "2012-08-07",
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          editors: [
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            {
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              name:       "Rich Tibbett",
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              //url:        "http://richt.me/",
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              company:    "Opera Software ASA",
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              companyURL: "http://opera.com/"
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            },
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            {
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              name:       "Clarke Stevens",
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              //url:      "",
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              company:    "CableLabs",
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              companyURL: "http://cablelabs.com/"
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            }
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          ],
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          noIDLIn:      true,
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          wg:           "Device APIs and Policy Working Group",
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          wgURI:        "http://www.w3.org/2009/dap/",
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          wgPublicList: "public-device-apis",
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          wgPatentURI:  "http://www.w3.org/2004/01/pp-impl/43696/status"
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      };
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    </style>
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  </head>
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  <body>
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    <section id='abstract'>
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      <p>
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        This specification defines a mechanism for an HTML document to discover and subsequently communicate with <abbr title="Hypertext Transfer Protocol">HTTP</abbr>-based services
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        advertised via common discovery protocols within a user's network.
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      </p>
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    </section>
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    <section id='sotd'>
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      <p>
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        This document represents the early consensus of the group on the scope and features of the proposed
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        API.
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      </p>
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    </section>
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    <section class="informative">
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      <h3>Introduction</h3>
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      <p>To enable Web pages to connect and communicate with Local-networked Services provided over HTTP, this specification introduces the
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      <a href="#navigatornetworkservice"><code>NavigatorNetworkService</code></a> interface.</p>
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      <p>
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         Using this <abbr title="Application Programming Interface">API</abbr> consists of requesting a well-known service type, known by developers and advertised by Local-networked Devices. User authorization, where the user connects the web page to one or more discovered services,
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         is expected before the web page is able to interact with any Local-networked Services.
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      </p>
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      <p>
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         A web page creates a request to obtain connectivity to services running in the network by specifying a well-known discovery service type that it wishes to interact with.
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      </p>
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      <p>
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         The user agent, having captured all advertised services on the network from the Service Discovery mechanisms included in this recommendation, attempts to match
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      the requested service type to a discovered service according to the processing described herein.
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      </p>
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      <p>
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          If a service connectivity request is successful then the Web page is provided with the necessary information to communicate with the authorized Local-networked Service.
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          If the request fails then the Web page will receive an error callback containing an error code describing the cause of Local-networked Service connectivity failure.
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      </p>
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      <p>
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         Once connected to a Local-networked Service the Web page can send requests and receive responses to the Local-networked Service via the messaging format and appropriate channel inferred from the service type
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         authorized via the provided API.
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         The Web page, once connected, can also receive service-pushed events, in the messaging format supported by the Local-networked Device, if such event subscription functionality is provided by the
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         connected Local-networked Service.
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      </p>
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      <div class="example">
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       <p>Example of requesting a DNS-SD advertised service:</p>
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       <hr />
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       <pre class="highlight">function showServices( services ) {
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  // Show a list of all the services provided to the web page
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  for(var i = 0, l = services.length; i < l; i++) console.log( services[i].name );
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}
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navigator.getNetworkServices('zeroconf:_boxee-jsonrpc._tcp', showServices);</pre>
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      </div>
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      <div class="example">
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        <p>Example of requesting a UPnP advertised service, also handling error conditions:</p>
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        <hr />
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        <pre class="highlight">function showServices( services ) {
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  // Show a list of all the services provided to the web page
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  for(var i = 0, l = services.length; i < l; i++) console.log( services[i].name );
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}
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function error( e ) {
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  console.log( "Error occurred: " + e.code );
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}
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navigator.getNetworkServices('upnp:urn:schemas-upnp-org:service:ContentDirectory:1', showServices, error);</pre>
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      </div>
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      <div class="example">
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        <p>Example of requesting either a DNS-SD or UPnP advertised service:</p>
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        <hr />
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        <pre class="highlight">function showServices( services ) {
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  // Show a list of all the services provided to the web page (+ service type)
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  for(var i = 0, l = services.length; i < l; i++)
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     console.log( services[i].name + '(' + services[i].type + ')' );
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}
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navigator.getNetworkServices([
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  'zeroconf:_boxee-jsonrpc._tcp',
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  'upnp:urn:schemas-upnp-org:service:ContentDirectory:1'
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], showServices);</pre>
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      </div>
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      <p>For more detailed examples see the <a href="#examples">Examples</a> section.
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    </section>
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    <section
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     id='conformance'>
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     <p>Requirements phrased in the imperative as part of algorithms (such as "strip any leading space characters" or "return false and abort these steps") are to be interpreted with the
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     meaning of the key word ("must", "should", "may", etc) used in introducing the algorithm.</p>
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     <p>
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      Some conformance requirements are phrased as requirements on attributes, methods or objects. Such requirements are to be interpreted as requirements on user agents.
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     </p>
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     <p>
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      Conformance requirements phrased as algorithms or specific steps may be implemented in any manner, so long as the end result is equivalent. (In particular, the algorithms defined in
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      this specification are intended to be easy to follow, and not intended to be performant.)
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     </p>
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     <p>
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      The only conformance class defined by this specification is a <dfn>user agent</dfn>.
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     </p>
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     <p>
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      User agents may impose implementation-specific limits on otherwise unconstrained inputs, e.g. to prevent denial of service attacks, to guard against running out of memory, or to work
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      around platform-specific limitations.
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     </p>
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     <p>
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      When support for a feature is disabled (e.g. as an emergency measure to mitigate a security problem, or to aid in development, or for performance reasons), user agents must act as if
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      they had no support for the feature whatsoever, and as if the feature was not mentioned in this specification. For example, if a particular feature is accessed via an attribute in a Web
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      IDL interface, the attribute itself would be omitted from the objects that implement that interface - leaving the attribute on the object but making it return null or throw an exception
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      is insufficient.
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     </p>
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      <section>
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         <h3>Dependencies</h3>
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         This specification relies on several other underlying specifications.
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         <dl>
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            <dt>HTML</dt>
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            <dd>Many fundamental concepts from HTML are used by this specification. [[!HTML5]]</dd>
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            <dt>WebIDL</dt>
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            <dd>The IDL blocks in this specification use the semantics of the WebIDL specification. [[!WEBIDL]]</dd>
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         </dl>
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      </section>
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    </section>
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    <section>
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      <h3>Terminology</h3>
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      <p>
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         The construction "a <code>Foo</code> object", where <code>Foo</code> is actually an interface, is sometimes used instead of the more accurate "an object implementing the interface <code>Foo</code>".
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      </p>
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      <p>
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         The term DOM is used to refer to the API set made available to scripts in Web applications, and does not necessarily imply the existence of an actual <code>Document</code> object or of any
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         other <code>Node</code> objects as defined in the DOM Core specifications. [[!DOM4]]
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      </p>
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      <p>
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         An IDL attribute is said to be <em>getting</em> when its value is being retrieved (e.g. by author script), and is said to be <em>setting</em> when a new value is assigned to it.
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      </p>
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      <p>
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        A <dfn>valid service type</dfn> is a string that begins with <code>upnp:</code> or <code>zeroconf:</code> followed by one or more characters in the ranges U+0021, U+0023 to U+0027, U+002A to U+002B, U+002D to U+002E, U+0030 to U+0039, U+0041 to U+005A, U+005E to U+007E.
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      </p>
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      <p>
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        A <a>valid service type</a> provided in the <code>type</code> attribute of the <code>getNetworkServices()</code> method will be matched against the services currently contained in the <a>list of available service records</a> according to the algorithms defined in this specification.
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      </p>
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    </section>
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    <section>
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     <h2>Requesting networked services</h2>
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<pre class="widl">[Supplemental, NoInterfaceObject]
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interface <dfn id="navigatornetworkservice">NavigatorNetworkService</dfn> {
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  // Obtain a Local-networked Service
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  void <a href="#dom-navigator-getnetworkservices">getNetworkServices</a>( in any type,
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                           in <a href="#navigatornetworkservicesuccesscallback">NavigatorNetworkServiceSuccessCallback</a> successCallback,
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                           in optional <a href="#navigatornetworkserviceerrorcallback">NavigatorNetworkServiceErrorCallback</a> errorCallback );
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};
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<a class="externalDFN" href="http://www.whatwg.org/specs/web-apps/current-work/complete/timers.html#navigator">Navigator</a> implements <a href="#navigatornetworkservice">NavigatorNetworkService</a>;
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[Callback=FunctionOnly, NoInterfaceObject]
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interface <dfn id="navigatornetworkservicesuccesscallback">NavigatorNetworkServiceSuccessCallback</dfn> {
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  void handleEvent( in <a href="#networkservices">NetworkServices</a> services );
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};
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[NoInterfaceObject]
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interface <dfn id="navigatornetworkserviceerror">NavigatorNetworkServiceError</dfn> {
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  const unsigned short <a href="#dom-navigatornetworkserviceerror-permission_denied">PERMISSION_DENIED_ERR</a> = 1;
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  const unsigned short <a href="#dom-navigatornetworkserviceerror-unknown_type_prefix">UNKNOWN_TYPE_PREFIX_ERR</a> = 2;
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  readonly attribute unsigned short <a href="#dom-navigatornetworkserviceerror-code">code</a>;
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};
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[Callback=FunctionOnly, NoInterfaceObject]
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interface <dfn id="navigatornetworkserviceerrorcallback">NavigatorNetworkServiceErrorCallback</dfn> {
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  void handleEvent( in <a href="#navigatornetworkserviceerror">NavigatorNetworkServiceError</a> error );
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};
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</pre>
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  <section>
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   <h2>Methods</h2>
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      <dl class="domintro">
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        <dt>
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          <var title="">window</var>
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           .
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          <code title="dom-navigator">
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            <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/timers.html#navigator">navigator</a>
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          </code>
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           .
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          <code title="dom-navigator-getNetworkServices">
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            <a href="#dom-navigator-getnetworkservices">getNetworkServices</a>
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          </code>
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          (
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          <var title="">type</var>
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          ,
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          <var title="">successCallback</var>
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           [,
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          <var title="">errorCallback</var>
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           ] )
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        </dt>
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        <dd>
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          <p>Prompts the user to select one or more discovered network services that have advertised support for the requested service type.</p>
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          <p>
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            The
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            <var title="">type</var>
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             argument contains one or more <a>valid service type</a> tokens that the web page would like to interact with.
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          </p>
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          <p>
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            If the user accepts, the
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            <var title="">successCallback</var>
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             is
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          invoked, with one or more
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            <code>
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              <a href="#networkservice"><code>NetworkService</code></a>
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            </code>
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             objects as
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          its argument.
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          </p>
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          <p>
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            If the user declines, the
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            <var title="">errorCallback</var>
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             (if
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          any) is invoked.
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          </p>
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        </dd>
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      </dl>
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       <div>
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          <p>
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            When the <dfn id="dom-navigator-getnetworkservices" title="dom-navigator-getnetworkservices"><code>getNetworkServices(type, successCallback[, errorCallback])</code></dfn> method is called, the <a>user agent</a> MUST run the following steps:
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          </p>
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          <ol class="rule">
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            <li>
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              Let <var>requested control types</var> be initially set to an empty array.
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            </li>
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            <li>
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               If <var>type</var> is an array consisting of one or more <a>valid service type</a> tokens, then let <var>requested control types</var> by the value of <var>type</var>, removing any non-<a>valid service type</a> tokens from the resulting array.
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            </li>
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            <li>
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               If <var>type</var> is a string consisting of one <a>valid service type</a> token, then let <var>requested control types</var> be an array containing one item with a value of <var>type</var>.
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            </li>
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            <li>
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               If <var>requested control types</var> is an array that contains at least one or more <a title="valid service type">valid service type</a> tokens then continue to the step labeled <em>process</em> below. Otherwise, the <a>user agent</a> MUST <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a> to invoke <var>errorCallback</var>, if it is provided and is an object of type <code>Function</code>, with a new <a href="#navigatornetworkserviceerror"><code>NavigatorNetworkServiceError</code></a> object whose
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                 <a href="#dom-navigatornetworkserviceerror-code"><code>code</code></a> attribute has the numeric value 2
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                  (<a href="#dom-navigatornetworkserviceerror-unknown_type_prefix"><code>UNKNOWN_TYPE_PREFIX_ERR</code></a>) as its argument,
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                   abort any remaining steps and return.
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            </li>
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            <li>
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               <em>Process</em>: Let <var>services found</var> be an empty array.
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            </li>
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            <li>
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               For each <var>available service</var> in the <a>list of available service records</a> run the following steps:
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               <ol class="rule">
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                  <li>
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                    For each <var>requested control type</var> in <var>requested control types</var>: If <var>available service</var>'s <code>type</code> attribute equals the <var>requested control type</var> then let <var>matched service</var> equal the value of <var>available service</var> and continue at the step labeled <var>attach</var> below.
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                  </li>
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                  <li>
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                     Continue at the next <var>available service</var>.
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                  </li>
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                  <li>
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   347
                     <em>Attach</em>: If <var>matched service</var> is not empty then run the following steps:
richt@180
   348
richt@180
   349
                     <ol class="rule">
richt@180
   350
                        <li>
richt@180
   351
                           Let <var>new service object</var> be a new <a href="#networkservice"><code>NetworkService</code></a> object, mapping the parameters of
richt@180
   352
                     <var>matched service</var> to this new object where possible.
richt@180
   353
                        </li>
richt@180
   354
                        <li>
richt@180
   355
                           Append <var>new service object</var> to the <var>services found</var> array.
richt@180
   356
                        </li>
richt@180
   357
                     </ol>
richt@180
   358
                  </li>
richt@180
   359
               </ol>
richt@180
   360
            </li>
richt@180
   361
richt@180
   362
            <li>
richt@180
   363
               If <var>services found</var> is an empty array, then the <a>user agent</a> MUST <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a> to invoke <var>errorCallback</var>, if it is provided and is an object of type <code>Function</code>, with a new <a href="#navigatornetworkserviceerror"><code>NavigatorNetworkServiceError</code></a> object whose
richt@180
   364
                 <a href="#dom-navigatornetworkserviceerror-code"><code>code</code></a> attribute has the numeric value 1
richt@180
   365
                 (<a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a>) as its argument, abort any remaining steps and return.
richt@180
   366
            </li>
richt@180
   367
richt@180
   368
            <li>
richt@180
   369
               Return, and run the remaining steps asynchronously.
richt@180
   370
            </li>
richt@180
   371
richt@180
   372
            <li>
richt@180
   373
               Optionally, e.g. based on a previously-established user preference, for security reasons, or due to platform limitations, the <a>user agent</a> MAY <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a> to invoke <var>errorCallback</var>, if it is provided and is an object of type <code>Function</code>, with a new <a href="#navigatornetworkserviceerror"><code>NavigatorNetworkServiceError</code></a> object whose
richt@180
   374
                 <a href="#dom-navigatornetworkserviceerror-code"><code>code</code></a> attribute has the numeric value 1
richt@180
   375
                 (<a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a>) as its argument, abort any remaining steps and return.
richt@180
   376
            </li>
richt@180
   377
richt@180
   378
            <li>
richt@180
   379
                  The <a>user agent</a> MUST prompt the user in a user-agent-specific manner for permission to provide the
richt@180
   380
                  <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/browsers.html#entry-script" class="externalDFN">entry script</a>'s
richt@180
   381
                  <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/origin-0.html#origin" class="externalDFN">origin</a> with an array of
richt@180
   382
                  <a href="#networkservice"><code>NetworkService</code></a> objects representing the user-authorized subset of <var>services found</var>.
richt@180
   383
richt@180
   384
               <p>
richt@180
   385
                  If the user grants permission to access one or more networked services then the <a>user agent</a> SHOULD include an
richt@180
   386
                  "ongoing local-network communication" indicator.
richt@180
   387
               </p>
richt@180
   388
richt@180
   389
               <p>If the user denies permission, then the <a>user agent</a> MUST <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a> to invoke <var>errorCallback</var>, if it is provided and is an object of type <code>Function</code>, with a new <a href="#navigatornetworkserviceerror"><code>NavigatorNetworkServiceError</code></a> object whose
richt@180
   390
                <a href="#dom-navigatornetworkserviceerror-code"><code>code</code></a> attribute has the numeric value 1
richt@180
   391
                (<a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a>) as its argument, abort any remaining steps and return.
richt@180
   392
              </p>
richt@180
   393
richt@180
   394
              <p>
richt@180
   395
                If the user never responds, this algorithm stalls on this step.
richt@180
   396
              </p>
richt@180
   397
richt@180
   398
            </li>
richt@180
   399
richt@180
   400
            <li>
richt@180
   401
               Let <var>services</var> be the array of one or more <a href="#networkservice"><code>NetworkService</code></a> objects for which the user granted permission.
richt@180
   402
            </li>
richt@180
   403
richt@180
   404
            <li>
richt@180
   405
               For each Object <var>service</var> in <var>services</var>, run the following substeps:
richt@180
   406
richt@180
   407
               <ol class="rule">
richt@180
   408
                  <li>
robin@185
   409
                     Add the <var>service</var>'s <code>url</code> parameter to the <a>entry script origin's <abbr title="Uniform Resource Locator">URL</abbr> whitelist</a>.
richt@180
   410
                  </li>
richt@180
   411
                  <li>
richt@191
   412
                    If <var>service</var>'s <code>type</code> parameter begins with the DOMString &quot;<code>upnp:</code>&quot; and the <var>service</var>'s <code>eventsUrl</code> parameter is not empty then <a>setup a UPnP Events Subscription</a> for <var>service</var>.
richt@180
   413
                  </li>
richt@180
   414
               </ol>
richt@180
   415
            </li>
richt@180
   416
richt@180
   417
            <li>
richt@180
   418
               Let <var>services manager</var> be a new <a href="#networkservices"><code>NetworkServices</code></a> object.
richt@180
   419
            </li>
richt@180
   420
richt@180
   421
            <li>
richt@191
   422
               Set <var>services manager</var>'s <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute to the length of <var>services</var>.
richt@180
   423
            </li>
richt@180
   424
richt@180
   425
            <li>
richt@180
   426
              Store the set of <var>services</var> as <dfn id="current_authorized_services">current authorized services</dfn> internally against the newly created <var>services manager</var> object.
richt@180
   427
            </li>
richt@180
   428
richt@180
   429
            <li>
richt@180
   430
               The <a>user agent</a> MUST <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a> to invoke <var>successCallback</var> with
richt@180
   431
               <var>services manager</var> as its argument.
richt@180
   432
            </li>
richt@180
   433
richt@180
   434
          </ol>
richt@180
   435
richt@180
   436
          <p>
richt@180
   437
            The <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#task-source" class="externalDFN">task source</a> for these
richt@180
   438
            <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#concept-task" class="externalDFN">tasks</a> is the
richt@180
   439
            <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#user-interaction-task-source" class="externalDFN">user interaction task source</a>.
richt@180
   440
          </p>
richt@180
   441
richt@180
   442
          <p>
richt@180
   443
            When a <a href="#networkservice"><code>NetworkService</code></a> object is provided to a Web page, the <a>user agent</a> MUST add the <code>url</code> property
richt@180
   444
             to the <dfn>entry script origin's URL whitelist</dfn>. This list enables the
richt@180
   445
            Web page to override and initiate cross-site resource requests towards these URLs, and any sub-resources of these URLs, within the current
richt@180
   446
            <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/browsers.html#entry-script" class="externalDFN">entry script</a>'s
richt@180
   447
            <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/origin-0.html#origin" class="externalDFN">origin</a> via various existing mechanisms (e.g. Web Sockets, Server-Sent Events,
richt@180
   448
            Web Messaging, XMLHttpRequest).
richt@180
   449
         </p>
richt@180
   450
richt@180
   451
         <p>
richt@180
   452
            If the user navigates away from the current browsing context, the <a>user agent</a> MUST remove all previously whitelisted urls from the <a>entry script origin's URL whitelist</a>.
richt@180
   453
            There is no persistence to network service selections provided to a web page. It is not possible to access a previously white-listed networked service without the necessary user authorization in all of the following cases:
richt@180
   454
            <ul>
richt@180
   455
              <li>If the current script is reloaded at any point in the same or different window.</li>
richt@180
   456
              <li>if the current script reinvokes the <a href="#dom-navigator-getnetworkservices"><code>getNetworkServices()</code></a> method at any point in its execution.</li>
richt@180
   457
              <li>If the user navigates forward or back in their history to reload the current page.</li>
richt@180
   458
              <li>If a script is running in a different origin.</li>
richt@180
   459
            </ul>
richt@180
   460
         </p>
richt@180
   461
richt@180
   462
      </div>
richt@180
   463
      </section>
richt@180
   464
richt@180
   465
      <section>
richt@180
   466
         <h3>Error Handling</h3>
richt@180
   467
richt@180
   468
      <dl class="domintro">
richt@180
   469
        <dt>
richt@180
   470
          <var title="">error</var>
richt@180
   471
           .
richt@180
   472
          <code title="dom-NavigatorNetworkServiceError-code">
richt@180
   473
            <a href="#dom-navigatornetworkserviceerror-code">code</a>
richt@180
   474
          </code>
richt@180
   475
        </dt>
richt@180
   476
        <dd>
richt@180
   477
          <p>
richt@180
   478
            Returns the current error's error code. At the current time, this may be <code>1</code> or <code>2</code>, for which the
richt@180
   479
            corresponding error constants
richt@180
   480
            <a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a> and
richt@180
   481
            <a href="#dom-navigatornetworkserviceerror-unknown_type_prefix"><code>UNKNOWN_TYPE_PREFIX_ERR</code></a> are defined.
richt@180
   482
          </p>
richt@180
   483
        </dd>
richt@180
   484
      </dl>
richt@180
   485
richt@180
   486
         <p>
richt@180
   487
            The <dfn id="dom-navigatornetworkserviceerror-code" title="dom-navigatornetworkserviceerror-code"><code>code</code></dfn> attribute of a
richt@180
   488
            <a href="#navigatornetworkserviceerror"><code>NavigatorNetworkServiceError</code></a> object MUST return the code for the error, which will be one of the following:
richt@180
   489
         </p>
richt@180
   490
richt@180
   491
         <dl>
richt@180
   492
            <dt>
richt@180
   493
               <dfn id="dom-navigatornetworkserviceerror-permission_denied" title="dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></dfn> (numeric value 1)
richt@180
   494
            </dt>
richt@180
   495
            <dd>
richt@194
   496
               The user or user agent denied the page permission to access any services.
richt@180
   497
            </dd>
richt@180
   498
            <dt>
richt@180
   499
               <dfn id="dom-navigatornetworkserviceerror-unknown_type_prefix" title="dom-navigatornetworkserviceerror-unknown_type_prefix"><code>UNKNOWN_TYPE_PREFIX_ERR</code></dfn> (numeric value 2)
richt@180
   500
            </dt>
richt@180
   501
            <dd>
richt@180
   502
               No <a>valid service type</a> tokens were provided in the method invocation.
richt@180
   503
            </dd>
richt@180
   504
         </dl>
richt@180
   505
richt@180
   506
      </section>
richt@180
   507
richt@180
   508
      </section>
richt@180
   509
      <section>
richt@180
   510
      <h2>Obtaining networked services</h2>
richt@180
   511
richt@180
   512
      <p>
richt@180
   513
         The <a href="#networkservices"><code>NetworkServices</code></a> interface is the top-level response object from a call to <a href="#dom-navigator-getnetworkservices"><code>getNetworkServices()</code></a> and provides access to a set of user-authorized <a href="#networkservice"><code>NetworkService</code></a> objects for the given request.
richt@180
   514
      </p>
richt@180
   515
richt@180
   516
<pre class="widl">
richt@180
   517
[NoInterfaceObject]
richt@180
   518
interface <dfn id="networkservices">NetworkServices</dfn> {
richt@180
   519
  readonly attribute unsigned long    <a href="#dom-networkservices-length">length</a>;
richt@180
   520
  getter <a href="#networkservice">NetworkService</a> (unsigned long index);
richt@180
   521
  <a href="#networkservice">NetworkService</a>? <a href="#dom-networkservices-getservicebyid">getServiceById</a>(DOMString id);
richt@180
   522
richt@180
   523
  readonly attribute unsigned long    <a href="#dom-networkservices-servicesavailable">servicesAvailable</a>;
richt@180
   524
richt@180
   525
  // event handler attributes
richt@180
   526
           attribute <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#eventhandler" class="externalDFN">EventHandler</a>     <a href="#dom-networkservices-onserviceavailable">onserviceavailable</a>;
richt@180
   527
           attribute <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#eventhandler" class="externalDFN">EventHandler</a>     <a href="#dom-networkservices-onserviceunavailable">onserviceunavailable</a>;
richt@180
   528
richt@180
   529
};
richt@180
   530
richt@180
   531
<a href="#networkservices">NetworkServices</a> implements <a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#interface-eventtarget" class="externalDFN">EventTarget</a>;
richt@180
   532
</pre>
richt@180
   533
richt@180
   534
      <section>
richt@180
   535
      <h2>Attributes</h2>
richt@180
   536
richt@180
   537
        <dl class="domintro">
richt@180
   538
          <dt>
richt@180
   539
            <code title="dom-networkservices-length">
richt@180
   540
              <a href="#dom-networkservices-length">length</a>
richt@180
   541
            </code>
richt@180
   542
          </dt>
richt@180
   543
          <dd>
richt@180
   544
            <p>
richt@180
   545
              Returns the current number of services in the respective object's <a>current authorized services</a>.
richt@180
   546
            </p>
richt@180
   547
          </dd>
richt@180
   548
          <dt>
richt@180
   549
            <code title="dom-networkservices-servicesavailable">
richt@180
   550
              <a href="#dom-networkservices-servicesavailable">servicesAvailable</a>
richt@180
   551
            </code>
richt@180
   552
          </dt>
richt@180
   553
          <dd>
richt@180
   554
            <p>
richt@180
   555
              Returns the current number of services matching one of the app-requested <a>valid service type</a> tokens that are actively available within the user's current network.
richt@180
   556
            </p>
richt@180
   557
          </dd>
richt@180
   558
        </dl>
richt@180
   559
richt@180
   560
        <div>
richt@180
   561
           <p>
richt@180
   562
              The <dfn id="dom-networkservices-length"><code>length</code></dfn> attribute MUST return the number of services represented in the object's corresponding <a>current authorized services</a> list at the time of getting.
richt@180
   563
           </p>
richt@180
   564
richt@180
   565
           <p>
richt@180
   566
              The <dfn id="dom-networkservices-servicesavailable"><code>servicesAvailable</code></dfn> attribute MUST return the number of services available in the
richt@180
   567
              user's network that match the <a>valid service type</a> that was initially used to create the current <a href="#networkservices"><code>NetworkServices</code></a> object.
richt@180
   568
           </p>
richt@180
   569
richt@180
   570
           <p>
richt@191
   571
             When a previously unknown instance of a networked service matching one of the requested <a href="#dfn-valid-service-type">valid service types</a> becomes available on the user's current network, the <a>user agent</a> MUST increment the <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute by <code>1</code> and then
richt@191
   572
             <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a>
richt@191
   573
             to dispatch a newly created event with the name <code>serviceavailable</code> that uses the <code>Event</code> interface, which does
richt@191
   574
             not bubble, is not cancellable, and has no default action, at the current <a href="#networkservices"><code>NetworkServices</code></a>
richt@191
   575
             object.
richt@180
   576
           </p>
richt@180
   577
richt@180
   578
           <p>
richt@191
   579
             When a previously known instance of a networked service matching one of the requested <a href="#dfn-valid-service-type">valid service types</a> becomes unavailable on the user's current network, the <a>user agent</a> MUST decrement the <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute by <code>1</code> and then
richt@191
   580
             <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a>
richt@191
   581
              to dispatch a newly created event with the name <code>serviceunavailable</code> that uses the <code>Event</code> interface, which does
richt@191
   582
              not bubble, is not cancellable, and has no default action, at the current <a href="#networkservices"><code>NetworkServices</code></a>
richt@191
   583
              object.
richt@180
   584
           </p>
richt@180
   585
        </div>
richt@180
   586
richt@180
   587
      </section>
richt@180
   588
richt@180
   589
      <section>
richt@180
   590
      <h2>Methods</h2>
richt@180
   591
        <dl class="domintro">
richt@180
   592
        <dt>
richt@180
   593
          <code title="networkservices-getter">
richt@180
   594
            <a href="#networkservices">services</a>
richt@180
   595
          </code>
richt@180
   596
          [
richt@180
   597
          <var title="">index</var>
richt@180
   598
          ]
richt@180
   599
        </dt>
richt@180
   600
        <dd>
richt@180
   601
          <p>
richt@180
   602
            Returns the specified <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
   603
          </p>
richt@180
   604
        </dd>
richt@180
   605
        <dt>
richt@180
   606
          <code title="networkservices-getter">
richt@180
   607
            <a href="#networkservices">services</a>
richt@180
   608
          </code>
richt@180
   609
          .
richt@180
   610
          <code title="dom-networkservices-getservicebyid">
richt@180
   611
            <a href="#dom-networkservices-getservicebyid">getServiceById</a>
richt@180
   612
          </code>
richt@180
   613
          (
richt@180
   614
          <var title="">id</var>
richt@180
   615
          )
richt@180
   616
        </dt>
richt@180
   617
        <dd>
richt@180
   618
          <p>
richt@180
   619
            Returns the <a href="#networkservice"><code>NetworkService</code></a> object with the given identifier, or null if no
richt@180
   620
            service has that identifier.
richt@180
   621
          </p>
richt@180
   622
        </dd>
richt@180
   623
      </dl>
richt@180
   624
richt@180
   625
      <p>
richt@191
   626
        A <a href="#networkservices"><code>NetworkServices</code></a> object represents the current list of zero or more <a>current authorized services</a>, of which zero or more can be available at a time. Each item in <a>current authorized services</a> is represented by a <a href="#networkservice"><code>NetworkService</code></a> object. The list of <a>current authorized services</a> is <span>immutable</span> meaning that it cannot be modified for the lifetime of a <a href="#networkservices"><code>NetworkServices</code></a> object.
richt@180
   627
      </p>
richt@180
   628
richt@180
   629
      <p class="note">
richt@180
   630
        Each service in a <a href="#networkservices"><code>NetworkServices</code></a> object thus has an index; the first has the index 0, and each subsequent service is numbered one higher than the previous one. If the <a>user agent</a> dynamically adds or removes network services for any reason, then the indices of the services in <a>current authorized services</a> will change dynamically. If the set of network services changes entirely, then all the previous services will be removed from <a>current authorized services</a> and replaced with new services.
richt@180
   631
      </p>
richt@180
   632
richt@180
   633
      <p>
richt@180
   634
        The <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#supported-property-indices" class="externalDFN">supported property indices</a> of <a href="#networkservices"><code>NetworkServices</code></a> objects at any instant are the numbers from zero to the number of items in <a>current authorized services</a> represented by the respective object minus one, if any services are represented in <a>current authorized services</a>. If a <a href="#networkservices"><code>NetworkServices</code></a> object represents no <a>current authorized services</a>, it has no <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#supported-property-indices" class="externalDFN">supported property indices</a>.
richt@180
   635
      </p>
richt@180
   636
richt@180
   637
      <p>
richt@180
   638
        To <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#determine-the-value-of-an-indexed-property" class="externalDFN">determine the value of an indexed property</a> for a given index <var>index</var> in a <a href="#networkservices"><code>NetworkServices</code></a> object's <a>current authorized services</a>, the user agent MUST return the <a href="#networkservice"><code>NetworkService</code></a> object that represents the <var>index</var>th service in <a>current authorized services</a>.
richt@180
   639
      </p>
richt@180
   640
richt@180
   641
      <p>
richt@180
   642
        The <dfn id="dom-networkservices-getservicebyid"><code>getServiceById(id)</code></dfn> method MUST return the first <a href="#networkservice"><code>NetworkService</code></a> object in <a>current authorized services</a> represented by the respective object whose <a href="#dom-networkservice-id"><code>id</code></a> attribute is equal to the value of the <var>id</var> argument.
richt@180
   643
        When no services in <a>current authorized services</a> match the given argument, the method MUST return null.
richt@180
   644
      </p>
richt@180
   645
richt@180
   646
      <p>
richt@180
   647
         Services available within the local network can connect and disconnect at different times during the execution of a web page. A <a>user agent</a> can
richt@180
   648
         inform a web page when the state of networked services matching the requested <a>valid service type</a> change. Web pages can use this information to enable in-page experiences for communicating the state of networked services
richt@180
   649
         with the ability to change the particular service or set of services the page is connected to by re-invoking the <a href="#dom-navigator-getnetworkservices"><code>getNetworkServices()</code></a> method.
richt@180
   650
      </p>
richt@180
   651
richt@180
   652
      </section>
richt@180
   653
richt@180
   654
      <section>
richt@180
   655
      <h2>Events</h2>
richt@180
   656
richt@180
   657
      <p>
richt@180
   658
         The following are the event handlers (and their corresponding event handler event types) that must be supported, as IDL attributes, by all objects implementing the <a href="#networkservices"><code>NetworkServices</code></a> interface:
richt@180
   659
       </p>
richt@180
   660
richt@180
   661
       <table border="1">
richt@180
   662
        <thead>
richt@180
   663
          <tr>
richt@180
   664
            <th>
richt@180
   665
              <span title="event handlers">Event handler</span>
richt@180
   666
            </th>
richt@180
   667
            <th>
richt@180
   668
              <span>Event handler event type</span>
richt@180
   669
            </th>
richt@180
   670
          </tr>
richt@180
   671
        </thead>
richt@180
   672
        <tbody>
richt@180
   673
          <tr>
richt@180
   674
            <td>
richt@180
   675
              <dfn id="dom-networkservices-onserviceavailable" title="dom-NetworkServices-onserviceavailable">
richt@180
   676
                <code>onserviceavailable</code>
richt@180
   677
              </dfn>
richt@180
   678
            </td>
richt@180
   679
            <td>
richt@180
   680
              <code title="event-serviceavailable">serviceavailable</code>
richt@180
   681
            </td>
richt@180
   682
          </tr>
richt@180
   683
          <tr>
richt@180
   684
            <td>
richt@180
   685
              <dfn id="dom-networkservices-onserviceunavailable" title="dom-NetworkServices-onserviceunavailable">
richt@180
   686
                <code>onserviceunavailable</code>
richt@180
   687
              </dfn>
richt@180
   688
            </td>
richt@180
   689
            <td>
richt@180
   690
              <code title="event-serviceunavailable">serviceunavailable</code>
richt@180
   691
            </td>
richt@180
   692
          </tr>
richt@180
   693
        </tbody>
richt@180
   694
      </table>
richt@180
   695
richt@180
   696
      <p>
richt@180
   697
         Events with an event type of <code>serviceavailable</code> or <code>serviceunavailable</code> defined in this specification are simple <code>Event</code> objects.
richt@180
   698
      </p>
richt@180
   699
richt@180
   700
      </section>
richt@180
   701
richt@180
   702
    </section>
richt@180
   703
    <section>
richt@180
   704
    <h2>Communicating with a networked service</h3>
richt@180
   705
richt@180
   706
<p>
richt@180
   707
   The <a href="#networkservice"><code>NetworkService</code></a> interface is used to provide a set of connection information for an HTTP service endpoint and if available, service events, running on a networked device.
richt@180
   708
</p>
richt@180
   709
richt@180
   710
<pre class="widl">
richt@180
   711
[NoInterfaceObject]
richt@180
   712
interface <dfn id="networkservice">NetworkService</dfn> {
richt@180
   713
  readonly attribute DOMString        <a href="#dom-networkservice-id">id</a>;
richt@180
   714
  readonly attribute DOMString        <a href="#dom-networkservice-name">name</a>;
richt@180
   715
  readonly attribute DOMString        <a href="#dom-networkservice-type">type</a>;
richt@180
   716
  readonly attribute DOMString        <a href="#dom-networkservice-url">url</a>;
richt@180
   717
  readonly attribute DOMString        <a href="#dom-networkservice-config">config</a>;
richt@180
   718
richt@191
   719
  readonly attribute boolean          <a href="#dom-networkservice-online">online</a>;
richt@180
   720
richt@180
   721
  // event handler attributes
richt@191
   722
           attribute <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#eventhandler" class="externalDFN">EventHandler</a>     <a href="#dom-networkservice-onserviceonline">onserviceonline</a>;
richt@191
   723
           attribute <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#eventhandler" class="externalDFN">EventHandler</a>     <a href="#dom-networkservice-onserviceoffline">onserviceoffline</a>;
richt@191
   724
richt@191
   725
           attribute <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#eventhandler" class="externalDFN">EventHandler</a>     <a href="#dom-networkservice-onnotify">onnotify</a>;
richt@180
   726
};
richt@180
   727
richt@180
   728
<a href="#networkservice">NetworkService</a> implements <a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#interface-eventtarget" class="externalDFN">EventTarget</a>;
richt@180
   729
</pre>
richt@180
   730
richt@180
   731
<section>
richt@180
   732
  <h2>Attributes</h2>
richt@180
   733
richt@180
   734
      <dl class="domintro">
richt@180
   735
        <dt>
richt@180
   736
          <var title="">service</var>
richt@180
   737
           .
richt@180
   738
          <code title="dom-networkservice-id">
richt@180
   739
            <a href="#dom-networkservice-id">id</a>
richt@180
   740
          </code>
richt@180
   741
        </dt>
richt@180
   742
        <dd>
richt@180
   743
          <p>
richt@180
   744
            A unique identifier for the given user-selected service instance.
richt@180
   745
          </p>
richt@180
   746
        </dd>
richt@180
   747
        <dt>
richt@180
   748
          <var title="">service</var>
richt@180
   749
           .
richt@180
   750
          <code title="dom-networkservice-name">
richt@180
   751
            <a href="#dom-networkservice-name">name</a>
richt@180
   752
          </code>
richt@180
   753
        </dt>
richt@180
   754
        <dd>
richt@180
   755
          <p>
richt@180
   756
            The name of the user-selected service.
richt@180
   757
          </p>
richt@180
   758
        </dd>
richt@180
   759
        <dt>
richt@180
   760
          <var title="">service</var>
richt@180
   761
           .
richt@180
   762
          <code title="dom-networkservice-type">
richt@180
   763
            <a href="#dom-networkservice-type">type</a>
richt@180
   764
          </code>
richt@180
   765
        </dt>
richt@180
   766
        <dd>
richt@180
   767
          <p>
richt@180
   768
            The <a>valid service type</a> token value of the user-selected service.
richt@180
   769
          </p>
richt@180
   770
        </dd>
richt@180
   771
        <dt>
richt@180
   772
          <var title="">service</var>
richt@180
   773
           .
richt@180
   774
          <code title="dom-networkservice-url">
richt@180
   775
            <a href="#dom-networkservice-url">url</a>
richt@180
   776
          </code>
richt@180
   777
        </dt>
richt@180
   778
        <dd>
richt@180
   779
          <p>
richt@180
   780
            The control URL endpoint (including any required port information) of the user-selected control service that has been added to the <a>entry script origin's URL whitelist</a>.
richt@180
   781
          </p>
richt@180
   782
        </dd>
richt@180
   783
        <dt>
richt@180
   784
          <var title="">service</var>
richt@180
   785
           .
richt@180
   786
          <code title="dom-networkservice-config">
richt@180
   787
            <a href="#dom-networkservice-config">config</a>
richt@180
   788
          </code>
richt@180
   789
        </dt>
richt@180
   790
        <dd>
richt@180
   791
          <p>
richt@180
   792
            The configuration information associated with the service depending on the requested service type.
richt@180
   793
          </p>
richt@180
   794
        </dd>
richt@180
   795
      </dl>
richt@180
   796
richt@180
   797
          <p>
richt@180
   798
            The <dfn id="dom-networkservice-id"><code>id</code></dfn> attribute is a unique identifier for the service. Two services provided at different times or on different objects MUST have the same <a href="#dom-networkservice-id"><code>id</code></a> value.
richt@180
   799
         </p>
richt@180
   800
richt@180
   801
         <p>
richt@180
   802
            The <dfn id="dom-networkservice-name"><code>name</code></dfn> attribute represents a human-readable title for the service.
richt@180
   803
         </p>
richt@180
   804
richt@180
   805
         <p>
richt@180
   806
             The <dfn id="dom-networkservice-type"><code>type</code></dfn> attribute reflects the value of the <a>valid service type</a> of the service.
richt@180
   807
          </p>
richt@180
   808
richt@180
   809
         <p>
richt@180
   810
            The <dfn id="dom-networkservice-url"><code>url</code></dfn> attribute is an <a href="http://www.w3.org/TR/html5/urls.html#absolute-url" class="externalDFN">absolute URL</a> pointing to the root HTTP
richt@180
   811
            endpoint for the service that has been added to the <a>entry script origin's URL whitelist</a>. Web pages can subsequently use this value for implicit cross-document messaging via various existing mechanisms (e.g. Web Sockets, Server-Sent Events, Web Messaging, XMLHttpRequest).
richt@180
   812
         </p>
richt@180
   813
richt@180
   814
         <p>
richt@180
   815
            The <dfn id="dom-networkservice-config"><code>config</code></dfn> attribute provides the raw configuration information extracted from the given network service.
richt@180
   816
         </p>
richt@180
   817
richt@180
   818
      </section>
richt@180
   819
richt@180
   820
      <section>
richt@180
   821
         <h3>States</h3>
richt@180
   822
richt@180
   823
      <dl class="domintro">
richt@180
   824
        <dt>
richt@180
   825
          <var title="">service</var>
richt@180
   826
           .
richt@191
   827
          <code title="dom-networkservice-online">
richt@191
   828
            <a href="#dom-networkservice-online">online</a>
richt@180
   829
          </code>
richt@180
   830
        </dt>
richt@180
   831
        <dd>
richt@180
   832
          <p>
richt@191
   833
            Returns <code>true</code> if the service is reporting that it is accessible on the local network or <code>false</code> if the service is reporting that it is no longer accessible (temporarily or permanently) on the local network.
richt@180
   834
          </p>
richt@180
   835
        </dd>
richt@180
   836
      </dl>
richt@180
   837
richt@191
   838
      <p>
richt@191
   839
        The <dfn id="dom-networkservice-config"><code>online</code></dfn> attribute indicates whether the service is reporting itself as being
richt@191
   840
        either <var>online</var>, and therefore accessible on the local network, in which case this attribute will return <code>true</code> or, <var>offline</var>, and therefore not accessible on the local network, either temporarily or permanently, in which case this attribute will return <code>false</code>. This attribute MUST default to <code>true</code>.
richt@191
   841
      </p>
richt@180
   842
richt@180
   843
      </section>
richt@180
   844
richt@180
   845
      <section>
richt@180
   846
         <h3>Events</h3>
richt@180
   847
richt@180
   848
      <p>
richt@180
   849
         The following are the event handlers (and their corresponding event handler event types) that must be supported, as IDL attributes, by all objects implementing the
richt@180
   850
         <a href="#networkservice"><code>NetworkService</code></a> interface:
richt@180
   851
       </p>
richt@180
   852
richt@180
   853
       <table border="1">
richt@180
   854
        <thead>
richt@180
   855
          <tr>
richt@180
   856
            <th>
richt@180
   857
              <span title="event handlers">Event handler</span>
richt@180
   858
            </th>
richt@180
   859
            <th>
richt@180
   860
              <span>Event handler event type</span>
richt@180
   861
            </th>
richt@180
   862
          </tr>
richt@180
   863
        </thead>
richt@180
   864
        <tbody>
richt@180
   865
          <tr>
richt@180
   866
            <td>
richt@191
   867
              <dfn id="dom-networkservice-onnotify" title="dom-NetworkService-onnotify">
richt@191
   868
                <code>onnotify</code>
richt@180
   869
              </dfn>
richt@180
   870
            </td>
richt@180
   871
            <td>
richt@191
   872
              <code title="event-notify">notify</code>
richt@180
   873
            </td>
richt@180
   874
          </tr>
richt@180
   875
          <tr>
richt@180
   876
            <td>
richt@191
   877
              <dfn id="dom-networkservice-onserviceonline" title="dom-NetworkService-onserviceonline">
richt@191
   878
                <code>onserviceonline</code>
richt@180
   879
              </dfn>
richt@180
   880
            </td>
richt@180
   881
            <td>
richt@191
   882
              <code title="event-onserviceonline">serviceonline</code>
richt@191
   883
            </td>
richt@191
   884
          </tr>
richt@191
   885
          <tr>
richt@191
   886
            <td>
richt@191
   887
              <dfn id="dom-networkservice-offserviceoffline" title="dom-NetworkService-onserviceoffline">
richt@191
   888
                <code>onserviceoffline</code>
richt@191
   889
              </dfn>
richt@191
   890
            </td>
richt@191
   891
            <td>
richt@191
   892
              <code title="event-onserviceoffline">serviceoffline</code>
richt@180
   893
            </td>
richt@180
   894
          </tr>
richt@180
   895
        </tbody>
richt@180
   896
      </table>
richt@180
   897
richt@180
   898
      <p>
richt@191
   899
         Events with an event type of <code>notify</code>, <code>serviceonline</code> or <code>serviceoffline</code> defined in this specification are simple <code>Event</code> objects.
richt@180
   900
      </p>
richt@180
   901
richt@180
   902
      </section>
richt@180
   903
   </section>
richt@180
   904
richt@180
   905
      <section>
richt@180
   906
            <h2>Service Discovery</h2>
richt@180
   907
richt@180
   908
      <p>
richt@192
   909
         A <a>user agent</a> conforming to this specification MAY implement <acronym title="Simple Service Discovery Protocol">SSDP</acronym> [[!UPNP-DEVICEARCH11]] and Zeroconf [[!DNS-SD]] + [[!MDNS]] service discovery mechanisms
richt@180
   910
         to enable Web pages to request and connect with HTTP services running on networked devices, discovered via either mechanism, through this API. When a <a>user agent</a> implements either of these service discovery mechanisms, then it MUST conform to the corresponding algorithms provided in this section of the specification.
richt@180
   911
      </p>
richt@180
   912
      <p>
richt@180
   913
         This section presents how the results of these two service discovery
richt@180
   914
         mechanisms will be matched to requested service types and how their properties will be applied to any resulting <a href="#networkservice"><code>NetworkService</code></a> objects.
richt@180
   915
      </p>
richt@180
   916
richt@180
   917
      <p>
richt@180
   918
         It is expected that user agents will perform these service discovery mechansisms asynchronously and periodically update the <a>list of networked devices</a> as required. The timing of any
richt@180
   919
         service discovery mechanisms is an implementation detail left to the discretion of the implementer (e.g. once on user agent start-up, every X seconds during user agent execution or on
richt@180
   920
         invocation of this API from a Web page).
richt@180
   921
      </p>
richt@180
   922
richt@180
   923
      <p>
richt@180
   924
         The <dfn>list of available service records</dfn> is a single dynamic internal lookup table within user agents that is used to track the current services available in the network at any given time.
richt@180
   925
         At any point during the running of either of the two service discovery mechanisms then existing entries within this table can be updated, entries can be added and entries can be removed as the status of networked
richt@180
   926
         services changes. Each record contained within this table contains the attributes: <code>id</code>, <code>name</code>, <code>type</code>, <code>url</code> and <code>config</code>.
richt@180
   927
      </p>
richt@180
   928
richt@180
   929
            <section>
robin@185
   930
         <h4>Zeroconf (<abbr title="Multicast DNS">mDNS</abbr> + <abbr title="Domain Name System">DNS</abbr>-<abbr title="Service Discovery">SD</abbr>)</h4>
richt@180
   931
richt@180
   932
         <p>
robin@185
   933
            For each DNS response received from a user-agent-initiated Multicast DNS Browse for <abbr title="DNS Pointer Record">PTR</abbr> records with the name <code>_services._dns-sd._udp</code> on the resolved recommended automatic browsing
richt@180
   934
   domain [[!MDNS]], the <a>user agent</a> MUST run the following steps:
richt@180
   935
         </p>
richt@180
   936
richt@180
   937
         <ol class="rule">
richt@180
   938
richt@180
   939
            <li>Let <var>service mDNS responses</var> be an array of PTR records received by issuing a Multicast DNS Browse for PTR records with the name of the current discovered service type.</li>
richt@180
   940
richt@180
   941
            <li>For each Object <var>service mDNS response</var> in <var>service mDNS responses</var>, run the following steps:
richt@180
   942
               <ol>
richt@180
   943
richt@180
   944
                  <li>
richt@180
   945
                     Let <var>network service record</var> be an Object consisting of the following empty properties: <code>id</code>, <code>name</code>, <code>type</code>, <code>url</code>, <code>config</code>.
richt@180
   946
                  </li>
richt@180
   947
richt@180
   948
                  <li>
richt@180
   949
                     Set <var>network service record</var>'s <code>id</code> property to the value of the full PTR Service Instance Name [[!MDNS]].
richt@180
   950
                  </li>
richt@180
   951
richt@180
   952
                  <li>
richt@180
   953
                     Set <var>network service record</var>'s <code>name</code> property to the value of the PTR Service Instance Name's <var>Instance</var> component [[!MDNS]].
richt@180
   954
                  </li>
richt@180
   955
richt@180
   956
                  <li>
richt@180
   957
                     Set <var>network service record</var>'s <code>type</code> property to the concatenation of the string <code>zeroconf:</code> followed by the value of the PTR Service Instance Name's <var>Service</var> component [[!MDNS]].
richt@180
   958
                  </li>
richt@180
   959
richt@180
   960
                  <li>
richt@180
   961
                     Set <var>network service record</var>'s <code>url</code> property to the resolvable Service URL obtained from performing an DNS-SD Lookup [[!DNS-SD]] of the current service from the PTR record provided [[!MDNS]].
richt@180
   962
                  </li>
richt@180
   963
richt@180
   964
                  <li>
richt@180
   965
                     Set <var>network service record</var>'s <code>config</code> property to the string value of the contents of the first DNS-SD TXT record associated with the <var>service mDNS response</var> as defined in [[!DNS-SD]].
richt@180
   966
                  </li>
richt@180
   967
richt@180
   968
                  <li>
richt@180
   969
                     For each Object <var>existing service record</var> in the current <a>list of available service records</a>, run the following sub-steps:
richt@180
   970
                     <ol class="rule">
richt@180
   971
richt@180
   972
                       <li>
richt@180
   973
                        If the <var>existing service record</var>'s <code>id</code> property matches the value of the <var>network service record</var>'s <code>id</code>, then set the
richt@180
   974
                        value of <var>existing service record</var> in the current <a>list of available service records</a>  to the value of the
richt@180
   975
                        <var>network service record</var> and skip the next step.
richt@180
   976
                       </li>
richt@180
   977
                     </ol>
richt@180
   978
                  </li>
richt@180
   979
richt@180
   980
                  <li>
richt@180
   981
                     Add <var>network service record</var> to the <a>list of available service records</a>.
richt@180
   982
                  </li>
richt@180
   983
richt@180
   984
                  <li>
richt@180
   985
                     For each non-garbage collected <a href="#networkservice"><code>NetworkService</code></a> object run the following steps:
richt@180
   986
richt@180
   987
                     <ol class="rule">
richt@180
   988
                        <li>
richt@180
   989
                           If the <a href="#networkservice"><code>NetworkService</code></a> object's <code>type</code> attribute does not equal the
richt@180
   990
                           current <a>network service record</a>'s <code>type</code> property then continue at the next available active
richt@180
   991
                           <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
   992
                        </li>
richt@180
   993
                        <li>
richt@191
   994
                           Increment the <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute of the <a href="#networkservices"><code>NetworkServices</code></a> object by <code>1</code>.
richt@191
   995
                        </li>
richt@191
   996
                        <li>
richt@191
   997
                          <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">Queue a task</a>
richt@191
   998
                           to dispatch a newly created event with the name <code>serviceavailable</code> that uses the <code>Event</code> interface, which does not bubble, is not cancellable, and has no default action, at the current
richt@191
   999
                            <a href="#networkservices"><code>NetworkServices</code></a> object.
richt@191
  1000
                        </li>
richt@191
  1001
                        <li>
richt@191
  1002
                          <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">Queue a task</a>
richt@191
  1003
                           to dispatch a newly created event with the name <code>serviceonline</code> that uses the <code>Event</code> interface, which does not bubble, is not cancellable, and has no default action, at the current
richt@191
  1004
                           <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
  1005
                        </li>
richt@180
  1006
                     </ol>
richt@180
  1007
                  </li>
richt@180
  1008
            </ol>
richt@180
  1009
           </li>
richt@180
  1010
         </ol>
richt@180
  1011
richt@180
  1012
      </section>
richt@180
  1013
richt@180
  1014
      <section>
robin@185
  1015
         <h5>Universal Plug-and-Play (<abbr title="Universal Plug-and-Play">UPnP</abbr>)</h5>
richt@180
  1016
richt@180
  1017
         <p>
robin@182
  1018
            For each SSDP Presence Announcement [[!UPNP-DEVICEARCH11]] - a HTTP NOTIFY request - received from a user-agent-initiated SSDP Discovery Request [[!UPNP-DEVICEARCH11]], the <a>user agent</a> MUST run the following steps:
richt@180
  1019
         </p>
richt@180
  1020
richt@180
  1021
         <ol class="rule">
richt@180
  1022
            <li>
richt@180
  1023
               Let <var>ssdp device</var> be an Object with a property for each HTTP header received in the received SSDP Presence Announcement, with each key being the name of a HTTP header and its
richt@180
  1024
               value being that HTTP header's accompanying value.
richt@180
  1025
            </li>
richt@180
  1026
richt@180
  1027
            <li>
richt@180
  1028
               If <var>ssdp device</var> does not contain at least one <var>NTS</var>, <var>USN</var> and <var>Location</var> parameter, then the <a>user agent</a> MUST abort these steps.
richt@180
  1029
            </li>
richt@180
  1030
richt@180
  1031
            <li>
richt@180
  1032
               If the first occurrence of <var>NTS</var> has a value other than <code>ssdp:alive</code>, then continue to the step labeled <var>update service monitor</var> below.
richt@180
  1033
            </li>
richt@180
  1034
richt@180
  1035
            <li>
richt@180
  1036
               Let <var>root device descriptor file</var> contain the contents of the file located at the URL provided in the first occurrence of <var>Location</var> obtained according to the rules
robin@182
  1037
               defined in the section 'Retrieving a description using HTTP' [[!UPNP-DEVICEARCH11]].
richt@180
  1038
            </li>
richt@180
  1039
richt@180
  1040
            <li>
richt@180
  1041
               If <var>root device descriptor file</var> is empty, then the <a>user agent</a> MUST abort these steps.
richt@180
  1042
            </li>
richt@180
  1043
richt@180
  1044
            <li>
richt@180
  1045
               Let <var>advertised services</var> be a <a>list of all advertised services</a> obtained from the <var>root device descriptor file</var> containing all sub-nodes of the <code>serviceList</code> node as described in
robin@182
  1046
               the section 'Device Description' [[!UPNP-DEVICEARCH11]].
richt@180
  1047
            </li>
richt@180
  1048
richt@180
  1049
            <li>
richt@180
  1050
               For each Object <var>advertised service</var> in <var>advertised services</var> run the following steps:
richt@180
  1051
               <ol class="rule">
richt@180
  1052
richt@180
  1053
                  <li>
richt@180
  1054
                     Let <var>network service record</var> be an Object consisting of the following empty properties: <code>id</code>, <code>name</code>, <code>type</code>, <code>url</code>, <code>eventsUrl</code>, <code>config</code>.
richt@180
  1055
                  </li>
richt@180
  1056
richt@180
  1057
                  <li>
richt@180
  1058
                     Set <var>network service record</var>'s <code>id</code> property to the string value of the first occurrence of <var>ssdp device</var>'s <var>USN</var> parameter.
richt@180
  1059
                  </li>
richt@180
  1060
richt@180
  1061
                  <li>
richt@180
  1062
                     Set <var>network service record</var>'s <code>name</code> property to the string value of the first occurrence of the <var>service</var>'s <code>serviceId</code> property.
richt@180
  1063
                  </li>
richt@180
  1064
richt@180
  1065
                  <li>
richt@180
  1066
                     Set <var>network service record</var>'s <code>type</code> property to the concatenation of the string <code>upnp:</code> followed by the string value of the first occurrence of the <var>service</var>'s <code>serviceType</code> property.
richt@180
  1067
                  </li>
richt@180
  1068
richt@180
  1069
                  <li>
richt@180
  1070
                     Set <var>network service record</var>'s <code>url</code> property to the string value of the first occurrence of the <var>service</var>'s <code>controlURL</code> property.
richt@180
  1071
                  </li>
richt@180
  1072
richt@180
  1073
                  <li>
richt@180
  1074
                     Set <var>network service record</var>'s <code>config</code> property to the string value of the first occurrence of the <var>device</var> property.
richt@180
  1075
                  </li>
richt@180
  1076
richt@180
  1077
                  <li>
richt@180
  1078
                     If <var>service</var>'s <code>eventSubURL</code> property is empty, then continue to the step labeled <em>register</em> below.
richt@180
  1079
                  </li>
richt@180
  1080
richt@180
  1081
                  <li>
richt@180
  1082
                     Set <var>network service record</var>'s <code>eventsUrl</code> property to the string value of the first occurrence of the <var>service</var>'s <code>eventSubURL</code> property.
richt@180
  1083
                  </li>
richt@180
  1084
richt@180
  1085
                  <li>
richt@180
  1086
                     <em>Register</em>: For each Object <var>existing service record</var> in the current <a>list of available service records</a>, run the following sub-steps:
richt@180
  1087
                     <ol class="rule">
richt@180
  1088
richt@180
  1089
                       <li>
richt@180
  1090
                        If the <var>existing service record</var>'s <var>id</var> property matches the value of the first occurrence of <var>USN</var> and the
richt@180
  1091
                        <var>existing service record</var>'s <code>type</code> property matches the value of <var>network service record</var>'s <code>type</code>, then set the
richt@180
  1092
                        value of <var>existing service record</var> in the current <a>list of available service records</a>  to the value of the
richt@180
  1093
                        <var>network service record</var> and skip the next step.
richt@180
  1094
                       </li>
richt@180
  1095
                     </ol>
richt@180
  1096
                  </li>
richt@180
  1097
richt@180
  1098
                  <li>
richt@180
  1099
                     Add <var>network service record</var> to the <a>list of available service records</a>.
richt@180
  1100
                  </li>
richt@180
  1101
richt@180
  1102
               </ol>
richt@180
  1103
            </li>
richt@180
  1104
            <li>
richt@180
  1105
               <em>Update Service Monitor</em>: For each non-garbage collected <a href="#networkservice"><code>NetworkService</code></a> object run the following steps:
richt@180
  1106
richt@180
  1107
               <ol class="rule">
richt@180
  1108
                  <li>
richt@180
  1109
                     If this <a href="#networkservice"><code>NetworkService</code></a> object's <code>type</code> attribute does not equal the
richt@180
  1110
                     current <a>network service record</a>'s <code>type</code> property then continue at the next available active
richt@180
  1111
                     <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
  1112
                  </li>
richt@180
  1113
                  <li>
richt@191
  1114
                     If the <var>announcement type</var> equals <code>ssdp:alive</code> then Increment the <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute of the <a href="#networkservices"><code>NetworkServices</code></a>
richt@191
  1115
                     object by <code>1</code> and then <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a>
richt@191
  1116
                      to dispatch a newly created event with the name <code>serviceonline</code> that uses the <code>Event</code> interface, which does not bubble, is not cancellable, and has no default action, at the current
richt@191
  1117
                      <a href="#networkservice"><code>NetworkService</code></a> object. Otherwise, decrement the <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute of the <a href="#networkservices"><code>NetworkServices</code></a>
richt@191
  1118
                     object by <code>1</code> and then  <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">queue a task</a>
richt@191
  1119
                       to dispatch a newly created event with the name <code>serviceoffline</code> that uses the <code>Event</code> interface, which does not bubble, is not cancellable, and has no default action, at the current
richt@191
  1120
                       <a href="#networkservice"><code>NetworkService</code></a> object..
richt@180
  1121
                  </li>
richt@180
  1122
               </ol>
richt@180
  1123
            </li>
richt@180
  1124
         </ol>
richt@180
  1125
richt@180
  1126
         <p>
richt@180
  1127
            A <dfn>user-agent generated callback url</dfn> is a Local-network accessible URL endpoint that a <a>user agent</a> must generate and maintain for receiving HTTP NOTIFY requests from UPnP Event sources.
richt@180
  1128
         </p>
richt@180
  1129
richt@180
  1130
         <p>When the <a>user agent</a> is to <dfn>setup a UPnP Events Subscription</dfn>, it is to run the following steps with the current <var>network service record</var> object:</p>
richt@180
  1131
richt@180
  1132
         <ol class="rule">
richt@180
  1133
            <li>
richt@180
  1134
               If <var>network service record</var>'s <code>eventsUrl</code> property is empty then the <a>user agent</a> MUST abort these steps.
richt@180
  1135
            </li>
richt@180
  1136
richt@180
  1137
            <li>
richt@180
  1138
               Let <var>callback URL</var> be the value of creating a new <a>user-agent generated callback url</a>.
richt@180
  1139
            </li>
richt@180
  1140
richt@180
  1141
            <li>
richt@191
  1142
               Send a HTTP SUBSCRIBE request with a <em>NT</em> header with a string value of <code>upnp:event</code>, a <em>TIMEOUT</em> header with an integer value ofÆ’
richt@180
  1143
               <code>86400</code> and a <em>CALLBACK</em> header
richt@180
  1144
               with a string value of <var>callback URL</var> towards the <var>network service record</var>'s <code>eventsUrl</code> property.
richt@180
  1145
            </li>
richt@180
  1146
richt@180
  1147
            <li>
richt@180
  1148
               If a non-200 OK response is received from the HTTP SUBSCRIBE request then the <a>user agent</a> MUST abort these steps.
richt@180
  1149
            </li>
richt@180
  1150
richt@180
  1151
            <li>
richt@180
  1152
               On receiving a valid 200 OK response, run the following steps:
richt@180
  1153
richt@180
  1154
               <ol class="rule">
richt@180
  1155
                  <li>
richt@180
  1156
                     Let <var>callback ID</var> equal the string value of the first included <em>SID</em> header, if it exists.
richt@180
  1157
                  </li>
richt@180
  1158
                  <li>
richt@180
  1159
                     Let <var>timeout date</var> equal the sum of the current UTC date value plus the integer value of the first included <em>TIMEOUT</em> header, if it exists.
richt@180
  1160
                  </li>
richt@180
  1161
                  <li>
richt@180
  1162
                     Run the following steps aynchronously and continue to the step labeled <em>listen</em> below.
richt@180
  1163
                  </li>
richt@180
  1164
                  <li>
richt@180
  1165
                     <em>Refresh Subscription</em>: Run the following steps at a set interval (X) within the <a>user agent</a>:
richt@180
  1166
richt@180
  1167
                     <ol class="rule">
richt@180
  1168
                        <li>
richt@180
  1169
                           Let <var>current date</var> equal the current UTC date.
richt@180
  1170
                        </li>
richt@180
  1171
                        <li>
richt@180
  1172
                           If <var>current date</var> is less than the <var>timeout date</var> then continue to the step labeled <em>refresh subscription</em> above.
richt@180
  1173
                        </li>
richt@180
  1174
                        <li>
richt@180
  1175
                           Send a HTTP SUBSCRIBE request with a <em>SID</em> header with the string value of <var>callback ID</var> and a <em>TIMEOUT</em> header
richt@180
  1176
                           with an integer value of <code>86400</code> towards the <var>network service record</var>'s <code>eventsUrl</code> property.
richt@180
  1177
                        </li>
richt@180
  1178
                        <li>
richt@180
  1179
                           On receiving a valid 200 OK, update <var>callback ID</var> with the string value of the first included <em>SID</em> header, if it exists. All other HTTP
richt@180
  1180
                           responses should cause the <a>user agent</a> to continue from the step labeled <em>refresh subscription</em> above.
richt@180
  1181
                        </li>
richt@180
  1182
                     </ol>
richt@180
  1183
richt@180
  1184
                  </li>
richt@180
  1185
richt@180
  1186
                  <li>
richt@180
  1187
                     <em>Listen</em>: For each HTTP NOTIFY request received at the <var>callback URL</var> the <a>user agent</a> is to run the following steps:
richt@180
  1188
richt@180
  1189
                     <ol class="rule">
richt@180
  1190
                        <li>
richt@180
  1191
                           Let <var>content clone</var> be the result of obtaining the message body of the HTTP NOTIFY request. If <var>content clone</var> is empty, then the <a>user agent</a> MUST abort these steps.
richt@180
  1192
                        </li>
richt@180
  1193
                        <li>
richt@191
  1194
                          Let <var>notification event</var> be a new simple event that uses the <code>Event</code> interface with the name <code>notify</code>,
richt@191
  1195
                           which does not bubble, is not cancellable, and has no default action.
richt@180
  1196
                        </li>
richt@180
  1197
                        <li>
richt@191
  1198
                           Let the <code>data</code> attribute of <var>notification event</var> have the DOMString value of <var>content clone</var>.
richt@180
  1199
                        </li>
richt@180
  1200
                        <li>
richt@180
  1201
                           <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">Queue a task</a> to
richt@191
  1202
                            dispatch <var>notification event</var> at the current <a><code>NetworkService</code></a> object.
richt@180
  1203
                        </li>
richt@180
  1204
                     </ol>
richt@180
  1205
                  </li>
richt@180
  1206
richt@180
  1207
               </ol>
richt@180
  1208
richt@180
  1209
            </li>
richt@180
  1210
         </ol>
richt@180
  1211
richt@180
  1212
         </section>
richt@180
  1213
richt@180
  1214
         <section>
richt@180
  1215
            <h3>Network Topology Monitoring</h3>
richt@180
  1216
richt@180
  1217
                  <div>
richt@180
  1218
                     <p>
richt@180
  1219
                        When the <a>user agent</a> detects that the user has dropped from their connected network, then it MUST run the following steps:
richt@180
  1220
                     </p>
richt@180
  1221
richt@180
  1222
                     <ol class="rule">
richt@180
  1223
                        <li>
richt@180
  1224
                           Flush all entries from the <a>list of available service records</a>.
richt@180
  1225
                        </li>
richt@180
  1226
                        <li>
richt@180
  1227
                           For each <a href="#networkservice"><code>NetworkService</code></a> object currently active in the <a>user agent</a> perform the following steps:
richt@180
  1228
richt@180
  1229
                           <ol class="rule">
richt@180
  1230
                              <li>
richt@191
  1231
                                 Set the <a href="#dom-networkservice-online"><code>online</code></a> attribute to <code>false</code>.
richt@180
  1232
                              </li>
richt@180
  1233
                              <li>
richt@191
  1234
                                 <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#queue-a-task" class="externalDFN">Queue a task</a>
richt@191
  1235
                                                      to dispatch a newly created event with the name <code>serviceoffline</code> that uses the <code>Event</code> interface, which does not bubble, is not cancellable, and has no default action, at the current
richt@191
  1236
                                                      <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
  1237
                           </ol>
richt@180
  1238
                        </li>
richt@191
  1239
                        <li>
richt@191
  1240
                          For each <a href="#networkservices"><code>NetworkServices</code></a> object currently active in the <a>user agent</a> perform the following steps:
richt@191
  1241
richt@191
  1242
                          <ol class="rule">
richt@191
  1243
                            <li>
richt@191
  1244
                              Let <var>number of available services</var> equal the value of <a href="#networkservices"><code>NetworkServices</code></a>'s <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute.
richt@191
  1245
                            </li>
richt@191
  1246
                            <li>
richt@191
  1247
                              Set the <a href="#networkservices"><code>NetworkServices</code></a>'s <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> attribute to zero (<code>0</code>).
richt@191
  1248
                            </li>
richt@191
  1249
                            <li>
richt@191
  1250
                              For each <var>available service</var> in <var>number of available services</var> the <a>user agent</a> MUST fire a new simple event with the name <code>serviceunavailable</code> that has no default action, does not bubble and is not cancellable, at the current <a href="#networkservices"><code>NetworkServices</code></a> object.
richt@191
  1251
                            </li>
richt@191
  1252
                          </ol>
richt@191
  1253
                        </li>
richt@191
  1254
richt@180
  1255
                     </ol>
richt@180
  1256
richt@180
  1257
                     <p>
richt@180
  1258
                        When the <a>user agent</a> detects that the user has connected to a new network, then it SHOULD run the following steps:
richt@180
  1259
                     </p>
richt@180
  1260
richt@180
  1261
                     <ol class="rule">
richt@180
  1262
                        <li>
richt@191
  1263
                           Re-issue an mDNS search and SSDP discovery search using all of the <a>valid service type</a> tokens initially provided to all active <a href="#networkservices"><code>NetworkServices</code></a> objects and handle all discovery responses according to the processing defined in <a href="#service-discovery">Section 7: Service Discovery</a>.
richt@180
  1264
                        </li>
richt@180
  1265
                     </ol>
richt@180
  1266
                  </div>
richt@180
  1267
         </section>
richt@180
  1268
      </section>
richt@180
  1269
richt@180
  1270
   <section>
richt@180
  1271
      <h3>Garbage collection</h3>
richt@180
  1272
richt@180
  1273
      <p>
richt@180
  1274
         A <a><code>NetworkService</code></a> object containing a <code>url</code> parameter currently in the <a>entry script origin's URL whitelist</a> MUST NOT be garbage collected.
richt@180
  1275
      </p>
richt@180
  1276
richt@180
  1277
      <p>
richt@180
  1278
         Only when the user navigates away from the current browsing context can <a><code>NetworkService</code></a> objects be garbage-collected and records in the <a>entry script origin's URL whitelist</a> be removed.
richt@180
  1279
      </p>
richt@180
  1280
richt@180
  1281
   </section>
richt@180
  1282
richt@180
  1283
richt@180
  1284
    <section>
richt@180
  1285
      <h3>Use Cases and Requirements</h3>
richt@180
  1286
richt@180
  1287
      <p>This section covers what the requirements are for this API, as well as illustrates some use cases.</p>
richt@180
  1288
richt@180
  1289
      <ul class="rule">
richt@180
  1290
         <li>
richt@180
  1291
            Once a user has given permission, user agents should provide the ability for Web pages to communicate directly with a Local-networked Service.
richt@180
  1292
            <ul class="rule">
richt@180
  1293
               <li>
richt@180
  1294
                  Example: A web-based TV remote control. A Web page wants to control the current user's TV, changing the programming shown or increasing/decreasing/muting the
richt@180
  1295
                  volume of the Local-networked Device. The Web page requests a service type that is known to be implemented by television sets to which it has the
richt@180
  1296
                  application logic to communicate. Local devices providing the request service types are discovered and presented to the user for authorization. The user selects one
richt@180
  1297
                  or more of the discovered television sets to be accessible to the current Web page and then clicks 'Share'. The Web page can now communicate directly with
richt@180
  1298
                  the user-authorized Local-networked services.
richt@180
  1299
               </li>
richt@180
  1300
            </ul>
richt@180
  1301
         </li>
richt@180
  1302
richt@180
  1303
         <li>
richt@180
  1304
           Web pages should be able to communicate with Local-networked Services using the messaging channel supported by those Devices.
richt@180
  1305
           <ul class="rule">
richt@180
  1306
            <li>
richt@180
  1307
               Example: A Web page advertises that it is capable of controlling multiple Home Media Servers. The user can select their Home Media Server type from a drop-down list, at which point the
richt@180
  1308
               Web page sends a request to the user agent to connect with the associated service type of the Home Media Server. The Media Server selected implements a Web Socket channel for
richt@180
  1309
               bi-directional service communication and so the Web page opens a web socket to the requested Media Server and can communicate as required via that appropriate channel.
richt@180
  1310
            </li>
richt@180
  1311
           </ul>
richt@180
  1312
         </li>
richt@180
  1313
richt@180
  1314
         <li>
richt@180
  1315
           Web pages should be able to communicate with Local-networked Services using the messaging format supported by those Devices.
richt@180
  1316
           <ul class="rule">
richt@180
  1317
            <li>
richt@180
  1318
               Example: A Web page advertises that it is capable of interacting with and controlling multiple types of Home Media Server. The user can select their Home Media Server type from a drop-down list or known Media Servers, at which point the
richt@180
  1319
               Web page sends a request to the user agent to connect with the associated service type (and, optionally, the associated event type) of the Home Media Server. The communiciation protocols supported by Home Media Servers typically vary
richt@180
  1320
               between UPnP, JSON-RPC, Protocol Buffers or other messaging formats depending on the Home Media Server requested. The Web page is able to communicate with the user-selected Home Media
richt@180
  1321
               Server in the messaging format supported by that Device, which, in this example is a simple key/value pair text format.
richt@180
  1322
            </li>
richt@180
  1323
           </ul>
richt@180
  1324
         </li>
richt@180
  1325
richt@180
  1326
         <li>
richt@180
  1327
           Web pages should not be able to communicate with Local-networked Services that have not been authorized by the user thereby maintaining the user's privacy.
richt@180
  1328
           <ul class="rule">
richt@180
  1329
            <li>
richt@180
  1330
               Example: A Web page requests access to one type of Local-networked service. The user authorizes access to that particular service. Other services running on that same device, and on other devices
richt@180
  1331
               within the network, should not be accessible to the current Web page.
richt@180
  1332
            </li>
richt@180
  1333
           </ul>
richt@180
  1334
         </li>
richt@180
  1335
richt@180
  1336
         <li>
richt@180
  1337
           A user should be able to share one or more Local-networked Services based on a particular service type request from a Web page.
richt@180
  1338
           <ul class="rule">
richt@180
  1339
            <li>
richt@180
  1340
               Example: A Web page is capable of interacting with a specific profile of Local-networked Service. As such, it makes a request to the user agent to access those services, of which multiple matches
richt@180
  1341
               are found. The user is capable of selecting one or more of the discovered services to share with the Web page. The Web page can then implement a drag-and-drop interface for the user to drag specific
richt@180
  1342
               actions on to one or more of the authorized Local-networked Services.
richt@180
  1343
            </li>
richt@180
  1344
           </ul>
richt@180
  1345
         </li>
richt@180
  1346
richt@180
  1347
         <li>
richt@180
  1348
           User agents should provide an API exposed to script that exposes the features above. The user is notified by UI anytime interaction with Local-networked Services is requested, giving the user
richt@180
  1349
           full ability to cancel or abort the transaction. The user selects the Local-networked Services to be connected to the current Web page, and can cancel these at any time. No invocations to
richt@180
  1350
           these APIs occur silently without user intervention.
richt@180
  1351
         </li>
richt@180
  1352
      </ul>
richt@180
  1353
    </section>
richt@180
  1354
richt@180
  1355
          <section class="informative appendix">
richt@180
  1356
             <h3>Examples</h3>
richt@180
  1357
richt@180
  1358
           <div class="example">
richt@180
  1359
            <p>This sample code exposes a button. When clicked, this button is disabled and the user is prompted to offer a network service. The user may also select multiple network services. When the user has authorized a network service to be connected to the web page then the web page issues a simple command to get a list of all the albums stored on the connected media player service.
richt@180
  1360
            <p>The button is re-enabled only when the connected network service disconnects for whatever reason (the service becomes unavailable on the network, the user disconnects from their current network or the user revokes access to the service from the current web page). At this point the user can re-click the button to select a new network service to connect to the web page and the above steps are repeated.</p>
richt@180
  1361
            <p>The provided service type identifier and service interaction used in this example is based on the well-defined service type and messaging format supported by the <a href="http://xbmc.org/about/">XBMC Media Server</a>. </p>
richt@180
  1362
            <hr />
robin@185
  1363
            <pre class="highlight">&lt;input type="button" value="Start" onclick="start()" id="startBtn"/&gt;
richt@180
  1364
&lt;div id="debugconsole">&lt;/div>
richt@180
  1365
richt@180
  1366
&lt;script>
richt@180
  1367
 var startBtn = document.getElementById('startBtn'),
richt@180
  1368
     debug = document.getElementById('debugconsole');
richt@180
  1369
richt@180
  1370
 function start() {
richt@180
  1371
   if(navigator.getNetworkServices) {
richt@180
  1372
      navigator.getNetworkServices('zeroconf:_xbmc-jsonrpc._tcp', gotXBMCService, error);
richt@180
  1373
      startBtn.disabled = true;
richt@180
  1374
   } else {
richt@191
  1375
      debug.innerHTML += "&lt;br&gt;Service Discovery not supported!";
richt@180
  1376
   }
richt@180
  1377
 }
richt@180
  1378
richt@180
  1379
 function gotXBMCService(services) {
richt@180
  1380
richt@180
  1381
// Listen for service disconnect messages
richt@180
  1382
richt@191
  1383
   services[0].addEventListener('serviceoffline', function ( e ) {
richt@180
  1384
       debug.innerHTML += "&lt;br>" + services[0].name + " disconnected.";
richt@180
  1385
       startBtn.disabled = false;
richt@180
  1386
   }, false);
richt@180
  1387
richt@180
  1388
// Send a service message to get albums list (and process the service response)
richt@180
  1389
richt@180
  1390
   var svcXhr = new XMLHttpRequest();
richt@180
  1391
   svcXhr.open("POST", services[0].url + "/getAlbums"); // services[0].url and its subresources have been
richt@180
  1392
                                                        // whitelisted for cross-site XHR use in this
richt@180
  1393
                                                        // current browsing context.
richt@180
  1394
richt@180
  1395
   svcXhr.setRequestHeader('Content-Type', 'application/json-rpc');
richt@180
  1396
richt@180
  1397
   svcXhr.addEventListener('readystatechange', function ( response ) {
richt@180
  1398
     if( response.readyState != 4 || response.status != 200 )
richt@180
  1399
        return;
richt@180
  1400
     debug.innerHTML += "&lt;br>" + services[0].name + " response received: ";
richt@180
  1401
     debug.textContent += JSON.parse(response.responseText);
richt@180
  1402
   }, false);
richt@180
  1403
richt@180
  1404
   var svcMsg = [
richt@180
  1405
     { "jsonrpc": "2.0", "method": "AudioLibrary.GetAlbums", "params": { "genreid": -1,
richt@180
  1406
         "artistid": -1, "start": -1, "end": -1 }, "id": "1" }
richt@180
  1407
   ];
richt@180
  1408
richt@180
  1409
   svcXhr.send(JSON.stringify(svcMsg));
richt@180
  1410
   debug.innerHTML += "&lt;br>" + services[0].name + " request sent: ";
richt@180
  1411
   debug.textContent += JSON.stringify(svcMsg);
richt@180
  1412
richt@180
  1413
 }
richt@180
  1414
richt@180
  1415
 function error( err ) {
richt@180
  1416
   debug.innerHTML += "&lt;br>An error occurred obtaining a local network service.";
richt@180
  1417
   startBtn.disabled = false;
richt@180
  1418
 }
richt@180
  1419
&lt;/script></pre>
richt@180
  1420
           </div>
richt@180
  1421
richt@180
  1422
           <div class="example">
richt@180
  1423
            <p>
richt@180
  1424
             This sample exposes a drop-down list containing a number of common Home-based audio devices. When the user selects an audio device from the list provided, they are prompted to authorize a network service
richt@180
  1425
             based on the service type requested. The user may also select multiple network services matching the selected service type.
richt@180
  1426
             In this example, the user selects their make as being <var>Sony</var> and their model as being <var>Bravia S1000</var> from which the Web page can derive a service type
richt@180
  1427
             (<var>urn:schemas-upnp-org:service:RenderingControl:1</var>).
richt@180
  1428
             <br /><br />Once the user has authorized the device, the web page sends a simple mute command according to the messaging format supported by the device.
richt@180
  1429
            </p>
richt@180
  1430
            <hr />
robin@185
  1431
            <pre class="highlight">&lt;select name="make" id="make"&gt;
richt@180
  1432
  &lt;option selected="selected" disabled="disabled"&gt;Select make&lt;/option&gt;
richt@180
  1433
  &lt;option&gt;Sony&lt;/option&gt;
richt@180
  1434
  &lt;option&gt;Philips&lt;/option&gt;
richt@180
  1435
  &lt;option&gt;Alba&lt;/option&gt;
richt@180
  1436
&lt;/select&gt;
richt@180
  1437
&lt;select name="model" id="model"&gt;&lt;/select&gt;
richt@180
  1438
&lt;div id="debugconsole"&gt;&lt;/div&gt;
richt@180
  1439
richt@180
  1440
&lt;script&gt;
richt@180
  1441
  var debug = document.getElementById('debugconsole');
richt@180
  1442
richt@180
  1443
  var models = {
richt@180
  1444
    "Sony": [
richt@180
  1445
      {"name": "Bravia TV S1000", "type": "upnp", "service": "urn:schemas-upnp-org:service:RenderingControl:1" },
richt@180
  1446
      {"name": "Bravia TV S2000", "type": "zeroconf", "service": "_mediarenderer._http._tcp" },
richt@180
  1447
      {"name": "HiFi WD10", "type": "upnp", "service": "urn:schemas-upnp-org:service:RenderingControl:1" }
richt@180
  1448
    ],
richt@180
  1449
    "Philips": [ /* ... */ ],
richt@180
  1450
    "Alba": [ /* ... */ ]
richt@180
  1451
  };
richt@180
  1452
richt@180
  1453
  var makeEl = document.getElementById("make"),
richt@180
  1454
      modelEl = document.getElementById("model");
richt@180
  1455
richt@180
  1456
  makeEl.addEventListener('change', function() {
richt@180
  1457
    modelEl.innerHTML = ""; // reset
richt@180
  1458
    var defaultOption = document.createElement("option");
richt@180
  1459
    defaultOption.textContent = "Select model";
richt@180
  1460
    defaultOption.setAttribute("disabled", "disabled");
richt@180
  1461
    defaultOption.setAttribute("selected", "selected");
richt@180
  1462
    modelEl.appendChild(defaultOption);
richt@180
  1463
    for(var i = 0, l = models[makeEl.value].length; i < l; i++) {
richt@180
  1464
      var option = document.createElement("option");
richt@180
  1465
      option.textContent = models[makeEl.value][i]["name"];
richt@180
  1466
      option.setAttribute("value", models[makeEl.value][i]["type"] + ":" + models[makeEl.value][i]["service"]);
richt@180
  1467
      modelEl.appendChild(option);
richt@180
  1468
    }
richt@180
  1469
  }, false);
richt@180
  1470
richt@180
  1471
  modelEl.addEventListener('change', function() {
richt@180
  1472
    if(navigator.getNetworkServices &&
richt@180
  1473
         modelEl.value == "upnp:urn:schemas-upnp-org:service:RenderingControl:1") {
richt@180
  1474
      navigator.getNetworkServices(modelEl.value, successCallback, errorCallback);
richt@180
  1475
    } else if (modelEl.value == "zeroconf:_mediarenderer._http._tcp") {
richt@180
  1476
      debug.innerHTML += "&lt;br&gt;Service type is not implemented by this application.";
richt@180
  1477
    } else {
richt@180
  1478
      debug.innerHTML += "&lt;br&gt;Service Discovery is not supported!";
richt@180
  1479
    }
richt@180
  1480
  }, false);
richt@180
  1481
&lt;/script&gt;
richt@180
  1482
richt@180
  1483
&lt;script&gt;
richt@180
  1484
  function successCallback( services ) {
richt@180
  1485
richt@191
  1486
  // Listen for service push notification messages
richt@180
  1487
richt@191
  1488
    services[0].addEventListener('notify', function ( msg ) {
richt@180
  1489
         debug.innerHTML += "&lt;br>" + services[0].name + " event received: ";
richt@180
  1490
         debug.textContent += msg.data;
richt@180
  1491
    }, false);
richt@180
  1492
richt@180
  1493
 // Send a control signal to mute the service audio
richt@180
  1494
richt@180
  1495
    var svcXhr = new XMLHttpRequest();
richt@180
  1496
    svcXhr.open("POST", services[0].url); // services[0].url and its
richt@180
  1497
                                          // subresources have been whitelisted for
richt@180
  1498
                                          // cross-site XHR use in this current
richt@180
  1499
                                          // browsing context.
richt@180
  1500
richt@180
  1501
    svcXhr.setRequestHeader('SOAPAction', 'urn:schemas-upnp-org:service:RenderingControl:1#SetMute');
richt@180
  1502
    svcXhr.setRequestHeader('Content-Type', 'text/xml; charset="utf-8";');
richt@180
  1503
richt@180
  1504
    svcXhr.onreadystatechange = function ( response ) {
richt@180
  1505
      if( response.readyState != 4 || response.status != 200 )
richt@180
  1506
        return;
richt@180
  1507
      debug.innerHTML += "&lt;br&gt;" + services[0].name + " response received: ";
richt@180
  1508
      debug.textContent += response.responseXML;
richt@180
  1509
    }
richt@180
  1510
richt@180
  1511
    // Service messaging to mute the provided service
richt@180
  1512
    var svcMsg = '&lt;?xml version="1.0" encoding="utf-8"?&gt;' +
richt@180
  1513
                 '&lt;s:Envelope s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" ' +
richt@180
  1514
                   'xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"&gt;' +
richt@180
  1515
                   '&lt;s:Body&gt;' +
richt@180
  1516
                     '&lt;u:SetMute xmlns:u="urn:schemas-upnp-org:service:RenderingControl:1"&gt;' +
richt@180
  1517
                       '&lt;InstanceID&gt;0&lt;/InstanceID&gt;' +
richt@180
  1518
                       '&lt;Channel&gt;Master&lt;/Channel&gt;' +
richt@180
  1519
                       '&lt;DesiredMute&gt;true&lt;/DesiredMute&gt;' +
richt@180
  1520
                     '&lt;/u:SetMute&gt;' +
richt@180
  1521
                   '&lt;/s:Body&gt;' +
richt@180
  1522
                 '&lt;/s:Envelope&gt;';
richt@180
  1523
richt@180
  1524
    svcXhr.send(svcMsg);
richt@180
  1525
    debug.innerHTML += "&lt;br&gt;" + services[0].name + " request sent: ";
richt@180
  1526
    debug.textContent += svcMsg;
richt@180
  1527
  }
richt@180
  1528
richt@180
  1529
  function errorCallback( error ) {
richt@180
  1530
    debug.innerHTML += "&lt;br&gt;An error occurred: " + error.code;
richt@180
  1531
  }
richt@180
  1532
&lt;/script&gt;</pre>
richt@180
  1533
          </div>
richt@180
  1534
richt@180
  1535
       </section>
richt@180
  1536
richt@180
  1537
    <section>
richt@180
  1538
      <h3>Acknowledgements</h3>
richt@180
  1539
richt@180
  1540
      <p>Thanks are expressed by the editor to the following individuals for their feedback on this specification to date (in alphabetical order):
richt@180
  1541
      <br /><br />
richt@191
  1542
      Gar Bergstedt, Lars-Erik Bolstad, Cathy Chan, Hari G Kumar, Bob Lund, Giuseppe Pascale, Marcin Simonides, Clarke Stevens, Christian S&ouml;derstr&ouml;m, Mark Vickers, ...</p>
richt@180
  1543
richt@180
  1544
      <p>Thanks are also expressed by the editor to the following organizations and groups for their support in producing this specification to date (in alphabetical order):
richt@180
  1545
      <br /></br />
richt@180
  1546
      CableLabs, Opera Software ASA, W3C Device APIs Working Group, W3C Web and TV Interest Group, ...</p>
richt@180
  1547
    </section>
richt@180
  1548
</body>
richt@180
  1549
</html>