discovery-api/Overview.src.html
author Robin Berjon <robin@berjon.com>
Fri, 03 Aug 2012 15:58:23 +0200
changeset 185 ef42cb5f9a60
parent 183 21b44409354f
child 192 3ecf12df315d
permissions -rw-r--r--
validity errors
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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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          specStatus: "ED",
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          shortName:  "discovery-api",
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          edDraftURI: "http://w3c-test.org/dap/discovery-api/",
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          editors: [
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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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                {   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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               If <var>successCallback</var> is empty or is not an object of type <code>Function</code> then the <a>user agent</a> MUST abort these steps.
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            </li>
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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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                     <em>Attach</em>: If <var>matched service</var> is not empty then run the following steps:
richt@180
   346
richt@180
   347
                     <ol class="rule">
richt@180
   348
                        <li>
richt@180
   349
                           Let <var>new service object</var> be a new <a href="#networkservice"><code>NetworkService</code></a> object, mapping the parameters of
richt@180
   350
                     <var>matched service</var> to this new object where possible.
richt@180
   351
                        </li>
richt@180
   352
                        <li>
richt@180
   353
                           Append <var>new service object</var> to the <var>services found</var> array.
richt@180
   354
                        </li>
richt@180
   355
                     </ol>
richt@180
   356
                  </li>
richt@180
   357
               </ol>
richt@180
   358
            </li>
richt@180
   359
richt@180
   360
            <li>
richt@180
   361
               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
   362
                 <a href="#dom-navigatornetworkserviceerror-code"><code>code</code></a> attribute has the numeric value 1
richt@180
   363
                 (<a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a>) as its argument, abort any remaining steps and return.
richt@180
   364
            </li>
richt@180
   365
richt@180
   366
            <li>
richt@180
   367
               Return, and run the remaining steps asynchronously.
richt@180
   368
            </li>
richt@180
   369
richt@180
   370
            <li>
richt@180
   371
               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
   372
                 <a href="#dom-navigatornetworkserviceerror-code"><code>code</code></a> attribute has the numeric value 1
richt@180
   373
                 (<a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a>) as its argument, abort any remaining steps and return.
richt@180
   374
            </li>
richt@180
   375
richt@180
   376
            <li>
richt@180
   377
                  The <a>user agent</a> MUST prompt the user in a user-agent-specific manner for permission to provide the
richt@180
   378
                  <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/browsers.html#entry-script" class="externalDFN">entry script</a>'s
richt@180
   379
                  <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
   380
                  <a href="#networkservice"><code>NetworkService</code></a> objects representing the user-authorized subset of <var>services found</var>.
richt@180
   381
richt@180
   382
               <p>
richt@180
   383
                  If the user grants permission to access one or more networked services then the <a>user agent</a> SHOULD include an
richt@180
   384
                  "ongoing local-network communication" indicator.
richt@180
   385
               </p>
richt@180
   386
richt@180
   387
               <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
   388
                <a href="#dom-navigatornetworkserviceerror-code"><code>code</code></a> attribute has the numeric value 1
richt@180
   389
                (<a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a>) as its argument, abort any remaining steps and return.
richt@180
   390
              </p>
richt@180
   391
richt@180
   392
              <p>
richt@180
   393
                If the user never responds, this algorithm stalls on this step.
richt@180
   394
              </p>
richt@180
   395
richt@180
   396
            </li>
richt@180
   397
richt@180
   398
            <li>
richt@180
   399
               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
   400
            </li>
richt@180
   401
richt@180
   402
            <li>
richt@180
   403
               For each Object <var>service</var> in <var>services</var>, run the following substeps:
richt@180
   404
richt@180
   405
               <ol class="rule">
richt@180
   406
                  <li>
robin@185
   407
                     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
   408
                  </li>
richt@180
   409
                  <li>
richt@180
   410
                    If <var>service</var> was originally created from a UPnP discovery process 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
   411
                  </li>
richt@180
   412
               </ol>
richt@180
   413
            </li>
richt@180
   414
richt@180
   415
            <li>
richt@180
   416
               Let <var>services manager</var> be a new <a href="#networkservices"><code>NetworkServices</code></a> object.
richt@180
   417
            </li>
richt@180
   418
richt@180
   419
            <li>
richt@180
   420
               Set <var>services manager</var>'s <code>servicesAvailable</code> attribute to the length of <var>services</var>.
richt@180
   421
            </li>
richt@180
   422
richt@180
   423
            <li>
richt@180
   424
              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
   425
            </li>
richt@180
   426
richt@180
   427
            <li>
richt@180
   428
               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
   429
               <var>services manager</var> as its argument.
richt@180
   430
            </li>
richt@180
   431
richt@180
   432
          </ol>
richt@180
   433
richt@180
   434
          <p>
richt@180
   435
            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
   436
            <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/webappapis.html#concept-task" class="externalDFN">tasks</a> is the
richt@180
   437
            <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
   438
          </p>
richt@180
   439
richt@180
   440
          <p>
richt@180
   441
            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
   442
             to the <dfn>entry script origin's URL whitelist</dfn>. This list enables the
richt@180
   443
            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
   444
            <a href="http://www.whatwg.org/specs/web-apps/current-work/complete/browsers.html#entry-script" class="externalDFN">entry script</a>'s
richt@180
   445
            <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
   446
            Web Messaging, XMLHttpRequest).
richt@180
   447
         </p>
richt@180
   448
richt@180
   449
         <p>
richt@180
   450
            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
   451
            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
   452
            <ul>
richt@180
   453
              <li>If the current script is reloaded at any point in the same or different window.</li>
richt@180
   454
              <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
   455
              <li>If the user navigates forward or back in their history to reload the current page.</li>
richt@180
   456
              <li>If a script is running in a different origin.</li>
richt@180
   457
            </ul>
richt@180
   458
         </p>
richt@180
   459
richt@180
   460
      </div>
richt@180
   461
      </section>
richt@180
   462
richt@180
   463
      <section>
richt@180
   464
         <h3>Error Handling</h3>
richt@180
   465
richt@180
   466
      <dl class="domintro">
richt@180
   467
        <dt>
richt@180
   468
          <var title="">error</var>
richt@180
   469
           .
richt@180
   470
          <code title="dom-NavigatorNetworkServiceError-code">
richt@180
   471
            <a href="#dom-navigatornetworkserviceerror-code">code</a>
richt@180
   472
          </code>
richt@180
   473
        </dt>
richt@180
   474
        <dd>
richt@180
   475
          <p>
richt@180
   476
            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
   477
            corresponding error constants
richt@180
   478
            <a href="#dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></a> and
richt@180
   479
            <a href="#dom-navigatornetworkserviceerror-unknown_type_prefix"><code>UNKNOWN_TYPE_PREFIX_ERR</code></a> are defined.
richt@180
   480
          </p>
richt@180
   481
        </dd>
richt@180
   482
      </dl>
richt@180
   483
richt@180
   484
         <p>
richt@180
   485
            The <dfn id="dom-navigatornetworkserviceerror-code" title="dom-navigatornetworkserviceerror-code"><code>code</code></dfn> attribute of a
richt@180
   486
            <a href="#navigatornetworkserviceerror"><code>NavigatorNetworkServiceError</code></a> object MUST return the code for the error, which will be one of the following:
richt@180
   487
         </p>
richt@180
   488
richt@180
   489
         <dl>
richt@180
   490
            <dt>
richt@180
   491
               <dfn id="dom-navigatornetworkserviceerror-permission_denied" title="dom-navigatornetworkserviceerror-permission_denied"><code>PERMISSION_DENIED_ERR</code></dfn> (numeric value 1)
richt@180
   492
            </dt>
richt@180
   493
            <dd>
richt@180
   494
               The user denied the page permission to access any services.
richt@180
   495
            </dd>
richt@180
   496
            <dt>
richt@180
   497
               <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
   498
            </dt>
richt@180
   499
            <dd>
richt@180
   500
               No <a>valid service type</a> tokens were provided in the method invocation.
richt@180
   501
            </dd>
richt@180
   502
         </dl>
richt@180
   503
richt@180
   504
      </section>
richt@180
   505
richt@180
   506
      </section>
richt@180
   507
      <section>
richt@180
   508
      <h2>Obtaining networked services</h2>
richt@180
   509
richt@180
   510
      <p>
richt@180
   511
         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
   512
      </p>
richt@180
   513
richt@180
   514
<pre class="widl">
richt@180
   515
[NoInterfaceObject]
richt@180
   516
interface <dfn id="networkservices">NetworkServices</dfn> {
richt@180
   517
  readonly attribute unsigned long    <a href="#dom-networkservices-length">length</a>;
richt@180
   518
  getter <a href="#networkservice">NetworkService</a> (unsigned long index);
richt@180
   519
  <a href="#networkservice">NetworkService</a>? <a href="#dom-networkservices-getservicebyid">getServiceById</a>(DOMString id);
richt@180
   520
richt@180
   521
  readonly attribute unsigned long    <a href="#dom-networkservices-servicesavailable">servicesAvailable</a>;
richt@180
   522
richt@180
   523
  // event handler attributes
richt@180
   524
           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
   525
           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
   526
richt@180
   527
};
richt@180
   528
richt@180
   529
<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
   530
</pre>
richt@180
   531
richt@180
   532
      <section>
richt@180
   533
      <h2>Attributes</h2>
richt@180
   534
richt@180
   535
        <dl class="domintro">
richt@180
   536
          <dt>
richt@180
   537
            <code title="dom-networkservices-length">
richt@180
   538
              <a href="#dom-networkservices-length">length</a>
richt@180
   539
            </code>
richt@180
   540
          </dt>
richt@180
   541
          <dd>
richt@180
   542
            <p>
richt@180
   543
              Returns the current number of services in the respective object's <a>current authorized services</a>.
richt@180
   544
            </p>
richt@180
   545
          </dd>
richt@180
   546
          <dt>
richt@180
   547
            <code title="dom-networkservices-servicesavailable">
richt@180
   548
              <a href="#dom-networkservices-servicesavailable">servicesAvailable</a>
richt@180
   549
            </code>
richt@180
   550
          </dt>
richt@180
   551
          <dd>
richt@180
   552
            <p>
richt@180
   553
              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
   554
            </p>
richt@180
   555
          </dd>
richt@180
   556
        </dl>
richt@180
   557
richt@180
   558
        <div>
richt@180
   559
           <p>
richt@180
   560
              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
   561
           </p>
richt@180
   562
richt@180
   563
           <p>
richt@180
   564
              The <dfn id="dom-networkservices-servicesavailable"><code>servicesAvailable</code></dfn> attribute MUST return the number of services available in the
richt@180
   565
              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
   566
              By default, <a href="#dom-networkservices-servicesavailable"><code>servicesAvailable</code></a> MUST be set to <code>1</code>.
richt@180
   567
           </p>
richt@180
   568
richt@180
   569
           <p>
richt@180
   570
             When a previously unknown instance of a networked service matching one or 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 fire a new simple
richt@180
   571
             event at the <a href="#dom-networkservices-onserviceavailable"><code>onserviceavailable</code></a> event handler.
richt@180
   572
           </p>
richt@180
   573
richt@180
   574
           <p>
richt@180
   575
             When a previously known instance of a networked service matching one or 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 fire a new simple
richt@180
   576
             event at the <a href="#dom-networkservices-onserviceunavailable"><code>onserviceunavailable</code></a> event handler.
richt@180
   577
           </p>
richt@180
   578
        </div>
richt@180
   579
richt@180
   580
      </section>
richt@180
   581
richt@180
   582
      <section>
richt@180
   583
      <h2>Methods</h2>
richt@180
   584
        <dl class="domintro">
richt@180
   585
        <dt>
richt@180
   586
          <code title="networkservices-getter">
richt@180
   587
            <a href="#networkservices">services</a>
richt@180
   588
          </code>
richt@180
   589
          [
richt@180
   590
          <var title="">index</var>
richt@180
   591
          ]
richt@180
   592
        </dt>
richt@180
   593
        <dd>
richt@180
   594
          <p>
richt@180
   595
            Returns the specified <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
   596
          </p>
richt@180
   597
        </dd>
richt@180
   598
        <dt>
richt@180
   599
          <code title="networkservices-getter">
richt@180
   600
            <a href="#networkservices">services</a>
richt@180
   601
          </code>
richt@180
   602
          .
richt@180
   603
          <code title="dom-networkservices-getservicebyid">
richt@180
   604
            <a href="#dom-networkservices-getservicebyid">getServiceById</a>
richt@180
   605
          </code>
richt@180
   606
          (
richt@180
   607
          <var title="">id</var>
richt@180
   608
          )
richt@180
   609
        </dt>
richt@180
   610
        <dd>
richt@180
   611
          <p>
richt@180
   612
            Returns the <a href="#networkservice"><code>NetworkService</code></a> object with the given identifier, or null if no
richt@180
   613
            service has that identifier.
richt@180
   614
          </p>
richt@180
   615
        </dd>
richt@180
   616
      </dl>
richt@180
   617
richt@180
   618
      <p>
richt@180
   619
        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.
richt@180
   620
      </p>
richt@180
   621
richt@180
   622
      <p class="note">
richt@180
   623
        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
   624
      </p>
richt@180
   625
richt@180
   626
      <p>
richt@180
   627
        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
   628
      </p>
richt@180
   629
richt@180
   630
      <p>
richt@180
   631
        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
   632
      </p>
richt@180
   633
richt@180
   634
      <p>
richt@180
   635
        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
   636
        When no services in <a>current authorized services</a> match the given argument, the method MUST return null.
richt@180
   637
      </p>
richt@180
   638
richt@180
   639
      <p>
richt@180
   640
         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
   641
         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
   642
         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
   643
      </p>
richt@180
   644
richt@180
   645
      </section>
richt@180
   646
richt@180
   647
      <section>
richt@180
   648
      <h2>Events</h2>
richt@180
   649
richt@180
   650
      <p>
richt@180
   651
         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
   652
       </p>
richt@180
   653
richt@180
   654
       <table border="1">
richt@180
   655
        <thead>
richt@180
   656
          <tr>
richt@180
   657
            <th>
richt@180
   658
              <span title="event handlers">Event handler</span>
richt@180
   659
            </th>
richt@180
   660
            <th>
richt@180
   661
              <span>Event handler event type</span>
richt@180
   662
            </th>
richt@180
   663
          </tr>
richt@180
   664
        </thead>
richt@180
   665
        <tbody>
richt@180
   666
          <tr>
richt@180
   667
            <td>
richt@180
   668
              <dfn id="dom-networkservices-onserviceavailable" title="dom-NetworkServices-onserviceavailable">
richt@180
   669
                <code>onserviceavailable</code>
richt@180
   670
              </dfn>
richt@180
   671
            </td>
richt@180
   672
            <td>
richt@180
   673
              <code title="event-serviceavailable">serviceavailable</code>
richt@180
   674
            </td>
richt@180
   675
          </tr>
richt@180
   676
          <tr>
richt@180
   677
            <td>
richt@180
   678
              <dfn id="dom-networkservices-onserviceunavailable" title="dom-NetworkServices-onserviceunavailable">
richt@180
   679
                <code>onserviceunavailable</code>
richt@180
   680
              </dfn>
richt@180
   681
            </td>
richt@180
   682
            <td>
richt@180
   683
              <code title="event-serviceunavailable">serviceunavailable</code>
richt@180
   684
            </td>
richt@180
   685
          </tr>
richt@180
   686
        </tbody>
richt@180
   687
      </table>
richt@180
   688
richt@180
   689
      <p>
richt@180
   690
         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
   691
      </p>
richt@180
   692
richt@180
   693
      </section>
richt@180
   694
richt@180
   695
    </section>
richt@180
   696
    <section>
richt@180
   697
    <h2>Communicating with a networked service</h3>
richt@180
   698
richt@180
   699
<p>
richt@180
   700
   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
   701
</p>
richt@180
   702
richt@180
   703
<pre class="widl">
richt@180
   704
[NoInterfaceObject]
richt@180
   705
interface <dfn id="networkservice">NetworkService</dfn> {
richt@180
   706
  readonly attribute DOMString        <a href="#dom-networkservice-id">id</a>;
richt@180
   707
  readonly attribute DOMString        <a href="#dom-networkservice-name">name</a>;
richt@180
   708
  readonly attribute DOMString        <a href="#dom-networkservice-type">type</a>;
richt@180
   709
  readonly attribute DOMString        <a href="#dom-networkservice-url">url</a>;
richt@180
   710
  readonly attribute DOMString        <a href="#dom-networkservice-config">config</a>;
richt@180
   711
richt@180
   712
  const unsigned short <a href="#dom-networkservice-AVAILABLE">AVAILABLE</a>      = 1;
richt@180
   713
  const unsigned short <a href="#dom-networkservice-UNAVAILABLE">UNAVAILABLE</a>    = 2;
richt@180
   714
  readonly attribute unsigned short   <a href="#dom-networkservice-readystate">readyState</a>;
richt@180
   715
richt@180
   716
  // event handler attributes
richt@180
   717
           attribute <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#eventhandler" class="externalDFN">EventHandler</a>     <a href="#dom-networkservice-onreadystatechange">onreadystatechange</a>;
richt@180
   718
           attribute <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#eventhandler" class="externalDFN">EventHandler</a>     <a href="#dom-networkservice-onmessage">onmessage</a>;
richt@180
   719
};
richt@180
   720
richt@180
   721
<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
   722
</pre>
richt@180
   723
richt@180
   724
<section>
richt@180
   725
  <h2>Attributes</h2>
richt@180
   726
richt@180
   727
      <dl class="domintro">
richt@180
   728
        <dt>
richt@180
   729
          <var title="">service</var>
richt@180
   730
           .
richt@180
   731
          <code title="dom-networkservice-id">
richt@180
   732
            <a href="#dom-networkservice-id">id</a>
richt@180
   733
          </code>
richt@180
   734
        </dt>
richt@180
   735
        <dd>
richt@180
   736
          <p>
richt@180
   737
            A unique identifier for the given user-selected service instance.
richt@180
   738
          </p>
richt@180
   739
        </dd>
richt@180
   740
        <dt>
richt@180
   741
          <var title="">service</var>
richt@180
   742
           .
richt@180
   743
          <code title="dom-networkservice-name">
richt@180
   744
            <a href="#dom-networkservice-name">name</a>
richt@180
   745
          </code>
richt@180
   746
        </dt>
richt@180
   747
        <dd>
richt@180
   748
          <p>
richt@180
   749
            The name of the user-selected service.
richt@180
   750
          </p>
richt@180
   751
        </dd>
richt@180
   752
        <dt>
richt@180
   753
          <var title="">service</var>
richt@180
   754
           .
richt@180
   755
          <code title="dom-networkservice-type">
richt@180
   756
            <a href="#dom-networkservice-type">type</a>
richt@180
   757
          </code>
richt@180
   758
        </dt>
richt@180
   759
        <dd>
richt@180
   760
          <p>
richt@180
   761
            The <a>valid service type</a> token value of the user-selected service.
richt@180
   762
          </p>
richt@180
   763
        </dd>
richt@180
   764
        <dt>
richt@180
   765
          <var title="">service</var>
richt@180
   766
           .
richt@180
   767
          <code title="dom-networkservice-url">
richt@180
   768
            <a href="#dom-networkservice-url">url</a>
richt@180
   769
          </code>
richt@180
   770
        </dt>
richt@180
   771
        <dd>
richt@180
   772
          <p>
richt@180
   773
            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
   774
          </p>
richt@180
   775
        </dd>
richt@180
   776
        <dt>
richt@180
   777
          <var title="">service</var>
richt@180
   778
           .
richt@180
   779
          <code title="dom-networkservice-config">
richt@180
   780
            <a href="#dom-networkservice-config">config</a>
richt@180
   781
          </code>
richt@180
   782
        </dt>
richt@180
   783
        <dd>
richt@180
   784
          <p>
richt@180
   785
            The configuration information associated with the service depending on the requested service type.
richt@180
   786
          </p>
richt@180
   787
        </dd>
richt@180
   788
      </dl>
richt@180
   789
richt@180
   790
          <p>
richt@180
   791
            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
   792
         </p>
richt@180
   793
richt@180
   794
         <p>
richt@180
   795
            The <dfn id="dom-networkservice-name"><code>name</code></dfn> attribute represents a human-readable title for the service.
richt@180
   796
         </p>
richt@180
   797
richt@180
   798
         <p>
richt@180
   799
             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
   800
          </p>
richt@180
   801
richt@180
   802
         <p>
richt@180
   803
            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
   804
            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
   805
         </p>
richt@180
   806
richt@180
   807
         <p>
richt@180
   808
            The <dfn id="dom-networkservice-config"><code>config</code></dfn> attribute provides the raw configuration information extracted from the given network service.
richt@180
   809
         </p>
richt@180
   810
richt@180
   811
      </section>
richt@180
   812
richt@180
   813
      <section>
richt@180
   814
         <h3>States</h3>
richt@180
   815
richt@180
   816
      <dl class="domintro">
richt@180
   817
        <dt>
richt@180
   818
          <var title="">service</var>
richt@180
   819
           .
richt@180
   820
          <code title="dom-networkservice-readystate">
richt@180
   821
            <a href="#dom-networkservice-readystate">readyState</a>
richt@180
   822
          </code>
richt@180
   823
        </dt>
richt@180
   824
        <dd>
richt@180
   825
          <p>
richt@180
   826
            Returns the current state.
richt@180
   827
          </p>
richt@180
   828
        </dd>
richt@180
   829
      </dl>
richt@180
   830
richt@180
   831
         A <a href="#networkservice"><code>NetworkService</code></a> object can be in several states. The <dfn id="dom-networkservice-readystate"><code>readyState</code></dfn> attribute MUST return the current state of the networked service,
richt@180
   832
         which MUST be one of the following values:
richt@180
   833
richt@180
   834
         <dl>
richt@180
   835
           <dt>
richt@180
   836
             <dfn id="dom-networkservice-AVAILABLE" title="dom-networkservice-AVAILABLE">
richt@180
   837
               <code>AVAILABLE</code>
richt@180
   838
             </dfn>
richt@180
   839
              (numeric value
richt@180
   840
             1)
richt@180
   841
richt@180
   842
richt@180
   843
           </dt>
richt@180
   844
           <dd>
richt@180
   845
             <p>The object is connected to its service endpoint.
richt@180
   846
richt@180
   847
            </p>
richt@180
   848
           </dd>
richt@180
   849
           <dt>
richt@180
   850
             <dfn id="dom-networkservice-UNAVAILABLE" title="dom-networkservice-UNAVAILABLE">
richt@180
   851
               <code>UNAVAILABLE</code>
richt@180
   852
             </dfn>
richt@180
   853
              (numeric value
richt@180
   854
             2)
richt@180
   855
           </dt>
richt@180
   856
           <dd>
richt@180
   857
             <p>The object is not connected to its service endpoint.
richt@180
   858
            </p>
richt@180
   859
           </dd>
richt@180
   860
         </dl>
richt@180
   861
richt@180
   862
      </section>
richt@180
   863
richt@180
   864
      <section>
richt@180
   865
         <h3>Events</h3>
richt@180
   866
richt@180
   867
      <p>
richt@180
   868
         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
   869
         <a href="#networkservice"><code>NetworkService</code></a> interface:
richt@180
   870
       </p>
richt@180
   871
richt@180
   872
       <table border="1">
richt@180
   873
        <thead>
richt@180
   874
          <tr>
richt@180
   875
            <th>
richt@180
   876
              <span title="event handlers">Event handler</span>
richt@180
   877
            </th>
richt@180
   878
            <th>
richt@180
   879
              <span>Event handler event type</span>
richt@180
   880
            </th>
richt@180
   881
          </tr>
richt@180
   882
        </thead>
richt@180
   883
        <tbody>
richt@180
   884
          <tr>
richt@180
   885
            <td>
richt@180
   886
              <dfn id="dom-networkservice-onmessage" title="dom-NetworkService-onmessage">
richt@180
   887
                <code>onmessage</code>
richt@180
   888
              </dfn>
richt@180
   889
            </td>
richt@180
   890
            <td>
richt@180
   891
              <code title="event-message">message</code>
richt@180
   892
            </td>
richt@180
   893
          </tr>
richt@180
   894
          <tr>
richt@180
   895
            <td>
richt@180
   896
              <dfn id="dom-networkservice-onreadystatechange" title="dom-NetworkService-onreadystatechange">
richt@180
   897
                <code>onreadystatechange</code>
richt@180
   898
              </dfn>
richt@180
   899
            </td>
richt@180
   900
            <td>
richt@180
   901
              <code title="event-onreadystatechange">readystatechange</code>
richt@180
   902
            </td>
richt@180
   903
          </tr>
richt@180
   904
        </tbody>
richt@180
   905
      </table>
richt@180
   906
richt@180
   907
      <p>
robin@182
   908
         Events with an event type of <code>message</code> defined in this specification are <a href="http://dev.w3.org/html5/postmsg/#messageevent" class="externalDFN"><code>MessageEvent</code></a> objects as defined in [[!POSTMSG]].
richt@180
   909
      </p>
richt@180
   910
richt@180
   911
      <p>
richt@180
   912
         Events with an event type of <code>readystatechange</code> defined in this specification are simple <code>Event</code> objects.
richt@180
   913
      </p>
richt@180
   914
richt@180
   915
      </section>
richt@180
   916
   </section>
richt@180
   917
richt@180
   918
      <section>
richt@180
   919
            <h2>Service Discovery</h2>
richt@180
   920
richt@180
   921
      <p>
robin@185
   922
         A <a>user agent</a> conforming to this specification MAY implement <abbr title="Simple Service Discovery Protocol">SSDP</abbr> [[!UPNP-DEVICEARCH11]] and Zeroconf [[!ZEROCONF]] service discovery mechanisms
richt@180
   923
         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
   924
      </p>
richt@180
   925
      <p>
richt@180
   926
         This section presents how the results of these two service discovery
richt@180
   927
         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
   928
      </p>
richt@180
   929
richt@180
   930
      <p>
richt@180
   931
         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
   932
         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
   933
         invocation of this API from a Web page).
richt@180
   934
      </p>
richt@180
   935
richt@180
   936
      <p>
richt@180
   937
         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
   938
         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
   939
         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
   940
      </p>
richt@180
   941
richt@180
   942
            <section>
robin@185
   943
         <h4>Zeroconf (<abbr title="Multicast DNS">mDNS</abbr> + <abbr title="Domain Name System">DNS</abbr>-<abbr title="Service Discovery">SD</abbr>)</h4>
richt@180
   944
richt@180
   945
         <p>
robin@185
   946
            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
   947
   domain [[!MDNS]], the <a>user agent</a> MUST run the following steps:
richt@180
   948
         </p>
richt@180
   949
richt@180
   950
         <ol class="rule">
richt@180
   951
richt@180
   952
            <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
   953
richt@180
   954
            <li>For each Object <var>service mDNS response</var> in <var>service mDNS responses</var>, run the following steps:
richt@180
   955
               <ol>
richt@180
   956
richt@180
   957
                  <li>
richt@180
   958
                     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
   959
                  </li>
richt@180
   960
richt@180
   961
                  <li>
richt@180
   962
                     Set <var>network service record</var>'s <code>id</code> property to the value of the full PTR Service Instance Name [[!MDNS]].
richt@180
   963
                  </li>
richt@180
   964
richt@180
   965
                  <li>
richt@180
   966
                     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
   967
                  </li>
richt@180
   968
richt@180
   969
                  <li>
richt@180
   970
                     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
   971
                  </li>
richt@180
   972
richt@180
   973
                  <li>
richt@180
   974
                     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
   975
                  </li>
richt@180
   976
richt@180
   977
                  <li>
richt@180
   978
                     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
   979
                  </li>
richt@180
   980
richt@180
   981
                  <li>
richt@180
   982
                     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
   983
                     <ol class="rule">
richt@180
   984
richt@180
   985
                       <li>
richt@180
   986
                        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
   987
                        value of <var>existing service record</var> in the current <a>list of available service records</a>  to the value of the
richt@180
   988
                        <var>network service record</var> and skip the next step.
richt@180
   989
                       </li>
richt@180
   990
                     </ol>
richt@180
   991
                  </li>
richt@180
   992
richt@180
   993
                  <li>
richt@180
   994
                     Add <var>network service record</var> to the <a>list of available service records</a>.
richt@180
   995
                  </li>
richt@180
   996
richt@180
   997
                  <li>
richt@180
   998
                     For each non-garbage collected <a href="#networkservice"><code>NetworkService</code></a> object run the following steps:
richt@180
   999
richt@180
  1000
                     <ol class="rule">
richt@180
  1001
                        <li>
richt@180
  1002
                           If the <a href="#networkservice"><code>NetworkService</code></a> object's <code>type</code> attribute does not equal the
richt@180
  1003
                           current <a>network service record</a>'s <code>type</code> property then continue at the next available active
richt@180
  1004
                           <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
  1005
                        </li>
richt@180
  1006
                        <li>
richt@180
  1007
                           Increment the <code>servicesAvailable</code> attribute of the <a href="#networkservices"><code>NetworkServices</code></a> object by <code>1</code>.
richt@180
  1008
                        </li>
richt@180
  1009
                     </ol>
richt@180
  1010
                  </li>
richt@180
  1011
            </ol>
richt@180
  1012
           </li>
richt@180
  1013
         </ol>
richt@180
  1014
richt@180
  1015
      </section>
richt@180
  1016
richt@180
  1017
      <section>
robin@185
  1018
         <h5>Universal Plug-and-Play (<abbr title="Universal Plug-and-Play">UPnP</abbr>)</h5>
richt@180
  1019
richt@180
  1020
         <p>
robin@182
  1021
            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
  1022
         </p>
richt@180
  1023
richt@180
  1024
         <ol class="rule">
richt@180
  1025
            <li>
richt@180
  1026
               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
  1027
               value being that HTTP header's accompanying value.
richt@180
  1028
            </li>
richt@180
  1029
richt@180
  1030
            <li>
richt@180
  1031
               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
  1032
            </li>
richt@180
  1033
richt@180
  1034
            <li>
richt@180
  1035
               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
  1036
            </li>
richt@180
  1037
richt@180
  1038
            <li>
richt@180
  1039
               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
  1040
               defined in the section 'Retrieving a description using HTTP' [[!UPNP-DEVICEARCH11]].
richt@180
  1041
            </li>
richt@180
  1042
richt@180
  1043
            <li>
richt@180
  1044
               If <var>root device descriptor file</var> is empty, then the <a>user agent</a> MUST abort these steps.
richt@180
  1045
            </li>
richt@180
  1046
richt@180
  1047
            <li>
richt@180
  1048
               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
  1049
               the section 'Device Description' [[!UPNP-DEVICEARCH11]].
richt@180
  1050
            </li>
richt@180
  1051
richt@180
  1052
            <li>
richt@180
  1053
               For each Object <var>advertised service</var> in <var>advertised services</var> run the following steps:
richt@180
  1054
               <ol class="rule">
richt@180
  1055
richt@180
  1056
                  <li>
richt@180
  1057
                     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
  1058
                  </li>
richt@180
  1059
richt@180
  1060
                  <li>
richt@180
  1061
                     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
  1062
                  </li>
richt@180
  1063
richt@180
  1064
                  <li>
richt@180
  1065
                     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
  1066
                  </li>
richt@180
  1067
richt@180
  1068
                  <li>
richt@180
  1069
                     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
  1070
                  </li>
richt@180
  1071
richt@180
  1072
                  <li>
richt@180
  1073
                     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
  1074
                  </li>
richt@180
  1075
richt@180
  1076
                  <li>
richt@180
  1077
                     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
  1078
                  </li>
richt@180
  1079
richt@180
  1080
                  <li>
richt@180
  1081
                     If <var>service</var>'s <code>eventSubURL</code> property is empty, then continue to the step labeled <em>register</em> below.
richt@180
  1082
                  </li>
richt@180
  1083
richt@180
  1084
                  <li>
richt@180
  1085
                     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
  1086
                  </li>
richt@180
  1087
richt@180
  1088
                  <li>
richt@180
  1089
                     <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
  1090
                     <ol class="rule">
richt@180
  1091
richt@180
  1092
                       <li>
richt@180
  1093
                        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
  1094
                        <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
  1095
                        value of <var>existing service record</var> in the current <a>list of available service records</a>  to the value of the
richt@180
  1096
                        <var>network service record</var> and skip the next step.
richt@180
  1097
                       </li>
richt@180
  1098
                     </ol>
richt@180
  1099
                  </li>
richt@180
  1100
richt@180
  1101
                  <li>
richt@180
  1102
                     Add <var>network service record</var> to the <a>list of available service records</a>.
richt@180
  1103
                  </li>
richt@180
  1104
richt@180
  1105
               </ol>
richt@180
  1106
            </li>
richt@180
  1107
            <li>
richt@180
  1108
               <em>Update Service Monitor</em>: For each non-garbage collected <a href="#networkservice"><code>NetworkService</code></a> object run the following steps:
richt@180
  1109
richt@180
  1110
               <ol class="rule">
richt@180
  1111
                  <li>
richt@180
  1112
                     If this <a href="#networkservice"><code>NetworkService</code></a> object's <code>type</code> attribute does not equal the
richt@180
  1113
                     current <a>network service record</a>'s <code>type</code> property then continue at the next available active
richt@180
  1114
                     <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
  1115
                  </li>
richt@180
  1116
                  <li>
richt@180
  1117
                     If the <var>announcement type</var> equals <code>ssdp:alive</code> then Increment the <code>servicesAvailable</code> attribute of the <a href="#networkservices"><code>NetworkServices</code></a>
richt@180
  1118
                     object by <code>1</code>. Otherwise, decrement the <code>servicesAvailable</code> attribute of the <a href="#networkservices"><code>NetworkServices</code></a>
richt@180
  1119
                     object by <code>1</code>.
richt@180
  1120
                  </li>
richt@180
  1121
               </ol>
richt@180
  1122
            </li>
richt@180
  1123
         </ol>
richt@180
  1124
richt@180
  1125
         <p>
richt@180
  1126
            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
  1127
         </p>
richt@180
  1128
richt@180
  1129
         <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
  1130
richt@180
  1131
         <ol class="rule">
richt@180
  1132
            <li>
richt@180
  1133
               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
  1134
            </li>
richt@180
  1135
richt@180
  1136
            <li>
richt@180
  1137
               Let <var>callback URL</var> be the value of creating a new <a>user-agent generated callback url</a>.
richt@180
  1138
            </li>
richt@180
  1139
richt@180
  1140
            <li>
richt@180
  1141
               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 of
richt@180
  1142
               <code>86400</code> and a <em>CALLBACK</em> header
richt@180
  1143
               with a string value of <var>callback URL</var> towards the <var>network service record</var>'s <code>eventsUrl</code> property.
richt@180
  1144
            </li>
richt@180
  1145
richt@180
  1146
            <li>
richt@180
  1147
               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
  1148
            </li>
richt@180
  1149
richt@180
  1150
            <li>
richt@180
  1151
               On receiving a valid 200 OK response, run the following steps:
richt@180
  1152
richt@180
  1153
               <ol class="rule">
richt@180
  1154
                  <li>
richt@180
  1155
                     Let <var>callback ID</var> equal the string value of the first included <em>SID</em> header, if it exists.
richt@180
  1156
                  </li>
richt@180
  1157
                  <li>
richt@180
  1158
                     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
  1159
                  </li>
richt@180
  1160
                  <li>
richt@180
  1161
                     Run the following steps aynchronously and continue to the step labeled <em>listen</em> below.
richt@180
  1162
                  </li>
richt@180
  1163
                  <li>
richt@180
  1164
                     <em>Refresh Subscription</em>: Run the following steps at a set interval (X) within the <a>user agent</a>:
richt@180
  1165
richt@180
  1166
                     <ol class="rule">
richt@180
  1167
                        <li>
richt@180
  1168
                           Let <var>current date</var> equal the current UTC date.
richt@180
  1169
                        </li>
richt@180
  1170
                        <li>
richt@180
  1171
                           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
  1172
                        </li>
richt@180
  1173
                        <li>
richt@180
  1174
                           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
  1175
                           with an integer value of <code>86400</code> towards the <var>network service record</var>'s <code>eventsUrl</code> property.
richt@180
  1176
                        </li>
richt@180
  1177
                        <li>
richt@180
  1178
                           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
  1179
                           responses should cause the <a>user agent</a> to continue from the step labeled <em>refresh subscription</em> above.
richt@180
  1180
                        </li>
richt@180
  1181
                     </ol>
richt@180
  1182
richt@180
  1183
                  </li>
richt@180
  1184
richt@180
  1185
                  <li>
richt@180
  1186
                     <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
  1187
richt@180
  1188
                     <ol class="rule">
richt@180
  1189
                        <li>
richt@180
  1190
                           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
  1191
                        </li>
richt@180
  1192
                        <li>
robin@182
  1193
                          Create a new <code>message</code> event that uses the <a href="http://dev.w3.org/html5/postmsg/#messageevent" class="externalDFN"><code>MessageEvent</code></a> interface [[!POSTMSG]], with the name <code>message</code>,
richt@180
  1194
                           which does not bubble, is not cancelable, and has no default action.
richt@180
  1195
                        </li>
richt@180
  1196
                        <li>
richt@180
  1197
                           Let the <code>data</code> attribute of the event have the DOMString value of <var>content clone</var>.
richt@180
  1198
                        </li>
richt@180
  1199
                        <li>
richt@180
  1200
                           <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@180
  1201
                            dispatch the newly created event at the current <a><code>NetworkService</code></a> object.
richt@180
  1202
                        </li>
richt@180
  1203
                     </ol>
richt@180
  1204
                  </li>
richt@180
  1205
richt@180
  1206
               </ol>
richt@180
  1207
richt@180
  1208
            </li>
richt@180
  1209
         </ol>
richt@180
  1210
richt@180
  1211
         </section>
richt@180
  1212
richt@180
  1213
         <section>
richt@180
  1214
            <h3>Network Topology Monitoring</h3>
richt@180
  1215
richt@180
  1216
                  <div>
richt@180
  1217
                     <p>
richt@180
  1218
                        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
  1219
                     </p>
richt@180
  1220
richt@180
  1221
                     <ol class="rule">
richt@180
  1222
                        <li>
richt@180
  1223
                           Flush all entries from the <a>list of available service records</a>.
richt@180
  1224
                        </li>
richt@180
  1225
                        <li>
richt@180
  1226
                           For each <a href="#networkservice"><code>NetworkService</code></a> object currently active in the <a>user agent</a> perform the following steps:
richt@180
  1227
richt@180
  1228
                           <ol class="rule">
richt@180
  1229
                              <li>
richt@180
  1230
                                 Set the <a href="#dom-networkservice-readystate"><code>readyState</code></a> attribute to <code>2</code> (<a href="#dom-networkservice-UNAVAILABLE"><code>UNAVAILABLE</code></a>).
richt@180
  1231
                              </li>
richt@180
  1232
                              <li>
richt@180
  1233
                                 Create a new <code>readystatechange</code> event that uses the <code>Event</code> interface which does not bubble, is not cancelable, and has no default action.
richt@180
  1234
                              </li>
richt@180
  1235
                              <li>
richt@180
  1236
                                 <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@180
  1237
                                        dispatch the newly created event at the <a href="#networkservice"><code>NetworkService</code></a> object.
richt@180
  1238
                              </li>
richt@180
  1239
                           </ol>
richt@180
  1240
                        </li>
richt@180
  1241
                     </ol>
richt@180
  1242
richt@180
  1243
                     <p>
richt@180
  1244
                        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
  1245
                     </p>
richt@180
  1246
richt@180
  1247
                     <ol class="rule">
richt@180
  1248
                        <li>
richt@180
  1249
                           Re-issue an mDNS search and SSDP discovery search and handle the responses according to the processing defined in <a href="#service-discovery">Section 6: Service Discovery</a>.
richt@180
  1250
                        </li>
richt@180
  1251
                     </ol>
richt@180
  1252
                  </div>
richt@180
  1253
         </section>
richt@180
  1254
      </section>
richt@180
  1255
richt@180
  1256
   <section>
richt@180
  1257
      <h3>Garbage collection</h3>
richt@180
  1258
richt@180
  1259
      <p>
richt@180
  1260
         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
  1261
      </p>
richt@180
  1262
richt@180
  1263
      <p>
richt@180
  1264
         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
  1265
      </p>
richt@180
  1266
richt@180
  1267
   </section>
richt@180
  1268
richt@180
  1269
richt@180
  1270
    <section>
richt@180
  1271
      <h3>Use Cases and Requirements</h3>
richt@180
  1272
richt@180
  1273
      <p>This section covers what the requirements are for this API, as well as illustrates some use cases.</p>
richt@180
  1274
richt@180
  1275
      <ul class="rule">
richt@180
  1276
         <li>
richt@180
  1277
            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
  1278
            <ul class="rule">
richt@180
  1279
               <li>
richt@180
  1280
                  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
  1281
                  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
  1282
                  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
  1283
                  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
  1284
                  the user-authorized Local-networked services.
richt@180
  1285
               </li>
richt@180
  1286
            </ul>
richt@180
  1287
         </li>
richt@180
  1288
richt@180
  1289
         <li>
richt@180
  1290
           Web pages should be able to communicate with Local-networked Services using the messaging channel supported by those Devices.
richt@180
  1291
           <ul class="rule">
richt@180
  1292
            <li>
richt@180
  1293
               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
  1294
               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
  1295
               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
  1296
            </li>
richt@180
  1297
           </ul>
richt@180
  1298
         </li>
richt@180
  1299
richt@180
  1300
         <li>
richt@180
  1301
           Web pages should be able to communicate with Local-networked Services using the messaging format supported by those Devices.
richt@180
  1302
           <ul class="rule">
richt@180
  1303
            <li>
richt@180
  1304
               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
  1305
               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
  1306
               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
  1307
               Server in the messaging format supported by that Device, which, in this example is a simple key/value pair text format.
richt@180
  1308
            </li>
richt@180
  1309
           </ul>
richt@180
  1310
         </li>
richt@180
  1311
richt@180
  1312
         <li>
richt@180
  1313
           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
  1314
           <ul class="rule">
richt@180
  1315
            <li>
richt@180
  1316
               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
  1317
               within the network, should not be accessible to the current Web page.
richt@180
  1318
            </li>
richt@180
  1319
           </ul>
richt@180
  1320
         </li>
richt@180
  1321
richt@180
  1322
         <li>
richt@180
  1323
           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
  1324
           <ul class="rule">
richt@180
  1325
            <li>
richt@180
  1326
               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
  1327
               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
  1328
               actions on to one or more of the authorized Local-networked Services.
richt@180
  1329
            </li>
richt@180
  1330
           </ul>
richt@180
  1331
         </li>
richt@180
  1332
richt@180
  1333
         <li>
richt@180
  1334
           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
  1335
           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
  1336
           these APIs occur silently without user intervention.
richt@180
  1337
         </li>
richt@180
  1338
      </ul>
richt@180
  1339
    </section>
richt@180
  1340
richt@180
  1341
          <section class="informative appendix">
richt@180
  1342
             <h3>Examples</h3>
richt@180
  1343
richt@180
  1344
           <div class="example">
richt@180
  1345
            <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
  1346
            <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
  1347
            <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
  1348
            <hr />
robin@185
  1349
            <pre class="highlight">&lt;input type="button" value="Start" onclick="start()" id="startBtn"/&gt;
richt@180
  1350
&lt;div id="debugconsole">&lt;/div>
richt@180
  1351
richt@180
  1352
&lt;script>
richt@180
  1353
 var startBtn = document.getElementById('startBtn'),
richt@180
  1354
     debug = document.getElementById('debugconsole');
richt@180
  1355
richt@180
  1356
 function start() {
richt@180
  1357
   if(navigator.getNetworkServices) {
richt@180
  1358
      navigator.getNetworkServices('zeroconf:_xbmc-jsonrpc._tcp', gotXBMCService, error);
richt@180
  1359
      startBtn.disabled = true;
richt@180
  1360
   } else {
richt@180
  1361
      debug.innerHTML += "&lt;br&gt;Service Discovery API not supported!";
richt@180
  1362
   }
richt@180
  1363
 }
richt@180
  1364
richt@180
  1365
 function gotXBMCService(services) {
richt@180
  1366
richt@180
  1367
// Listen for service disconnect messages
richt@180
  1368
richt@180
  1369
   services[0].addEventListener('readystatechange', function ( e ) {
richt@180
  1370
     if(services[0].readyState === services[0].UNAVAILABLE) {
richt@180
  1371
       debug.innerHTML += "&lt;br>" + services[0].name + " disconnected.";
richt@180
  1372
       startBtn.disabled = false;
richt@180
  1373
     }
richt@180
  1374
   }, false);
richt@180
  1375
richt@180
  1376
// Send a service message to get albums list (and process the service response)
richt@180
  1377
richt@180
  1378
   var svcXhr = new XMLHttpRequest();
richt@180
  1379
   svcXhr.open("POST", services[0].url + "/getAlbums"); // services[0].url and its subresources have been
richt@180
  1380
                                                        // whitelisted for cross-site XHR use in this
richt@180
  1381
                                                        // current browsing context.
richt@180
  1382
richt@180
  1383
   svcXhr.setRequestHeader('Content-Type', 'application/json-rpc');
richt@180
  1384
richt@180
  1385
   svcXhr.addEventListener('readystatechange', function ( response ) {
richt@180
  1386
     if( response.readyState != 4 || response.status != 200 )
richt@180
  1387
        return;
richt@180
  1388
     debug.innerHTML += "&lt;br>" + services[0].name + " response received: ";
richt@180
  1389
     debug.textContent += JSON.parse(response.responseText);
richt@180
  1390
   }, false);
richt@180
  1391
richt@180
  1392
   var svcMsg = [
richt@180
  1393
     { "jsonrpc": "2.0", "method": "AudioLibrary.GetAlbums", "params": { "genreid": -1,
richt@180
  1394
         "artistid": -1, "start": -1, "end": -1 }, "id": "1" }
richt@180
  1395
   ];
richt@180
  1396
richt@180
  1397
   svcXhr.send(JSON.stringify(svcMsg));
richt@180
  1398
   debug.innerHTML += "&lt;br>" + services[0].name + " request sent: ";
richt@180
  1399
   debug.textContent += JSON.stringify(svcMsg);
richt@180
  1400
richt@180
  1401
 }
richt@180
  1402
richt@180
  1403
 function error( err ) {
richt@180
  1404
   debug.innerHTML += "&lt;br>An error occurred obtaining a local network service.";
richt@180
  1405
   startBtn.disabled = false;
richt@180
  1406
 }
richt@180
  1407
&lt;/script></pre>
richt@180
  1408
           </div>
richt@180
  1409
richt@180
  1410
           <div class="example">
richt@180
  1411
            <p>
richt@180
  1412
             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
  1413
             based on the service type requested. The user may also select multiple network services matching the selected service type.
richt@180
  1414
             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
  1415
             (<var>urn:schemas-upnp-org:service:RenderingControl:1</var>).
richt@180
  1416
             <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
  1417
            </p>
richt@180
  1418
            <hr />
robin@185
  1419
            <pre class="highlight">&lt;select name="make" id="make"&gt;
richt@180
  1420
  &lt;option selected="selected" disabled="disabled"&gt;Select make&lt;/option&gt;
richt@180
  1421
  &lt;option&gt;Sony&lt;/option&gt;
richt@180
  1422
  &lt;option&gt;Philips&lt;/option&gt;
richt@180
  1423
  &lt;option&gt;Alba&lt;/option&gt;
richt@180
  1424
&lt;/select&gt;
richt@180
  1425
&lt;select name="model" id="model"&gt;&lt;/select&gt;
richt@180
  1426
&lt;div id="debugconsole"&gt;&lt;/div&gt;
richt@180
  1427
richt@180
  1428
&lt;script&gt;
richt@180
  1429
  var debug = document.getElementById('debugconsole');
richt@180
  1430
richt@180
  1431
  var models = {
richt@180
  1432
    "Sony": [
richt@180
  1433
      {"name": "Bravia TV S1000", "type": "upnp", "service": "urn:schemas-upnp-org:service:RenderingControl:1" },
richt@180
  1434
      {"name": "Bravia TV S2000", "type": "zeroconf", "service": "_mediarenderer._http._tcp" },
richt@180
  1435
      {"name": "HiFi WD10", "type": "upnp", "service": "urn:schemas-upnp-org:service:RenderingControl:1" }
richt@180
  1436
    ],
richt@180
  1437
    "Philips": [ /* ... */ ],
richt@180
  1438
    "Alba": [ /* ... */ ]
richt@180
  1439
  };
richt@180
  1440
richt@180
  1441
  var makeEl = document.getElementById("make"),
richt@180
  1442
      modelEl = document.getElementById("model");
richt@180
  1443
richt@180
  1444
  makeEl.addEventListener('change', function() {
richt@180
  1445
    modelEl.innerHTML = ""; // reset
richt@180
  1446
    var defaultOption = document.createElement("option");
richt@180
  1447
    defaultOption.textContent = "Select model";
richt@180
  1448
    defaultOption.setAttribute("disabled", "disabled");
richt@180
  1449
    defaultOption.setAttribute("selected", "selected");
richt@180
  1450
    modelEl.appendChild(defaultOption);
richt@180
  1451
    for(var i = 0, l = models[makeEl.value].length; i < l; i++) {
richt@180
  1452
      var option = document.createElement("option");
richt@180
  1453
      option.textContent = models[makeEl.value][i]["name"];
richt@180
  1454
      option.setAttribute("value", models[makeEl.value][i]["type"] + ":" + models[makeEl.value][i]["service"]);
richt@180
  1455
      modelEl.appendChild(option);
richt@180
  1456
    }
richt@180
  1457
  }, false);
richt@180
  1458
richt@180
  1459
  modelEl.addEventListener('change', function() {
richt@180
  1460
    if(navigator.getNetworkServices &&
richt@180
  1461
         modelEl.value == "upnp:urn:schemas-upnp-org:service:RenderingControl:1") {
richt@180
  1462
      navigator.getNetworkServices(modelEl.value, successCallback, errorCallback);
richt@180
  1463
    } else if (modelEl.value == "zeroconf:_mediarenderer._http._tcp") {
richt@180
  1464
      debug.innerHTML += "&lt;br&gt;Service type is not implemented by this application.";
richt@180
  1465
    } else {
richt@180
  1466
      debug.innerHTML += "&lt;br&gt;Service Discovery is not supported!";
richt@180
  1467
    }
richt@180
  1468
  }, false);
richt@180
  1469
&lt;/script&gt;
richt@180
  1470
richt@180
  1471
&lt;script&gt;
richt@180
  1472
  function successCallback( services ) {
richt@180
  1473
richt@180
  1474
  // Listen for service push messages
richt@180
  1475
richt@180
  1476
    services[0].addEventListener('message', function ( msg ) {
richt@180
  1477
         debug.innerHTML += "&lt;br>" + services[0].name + " event received: ";
richt@180
  1478
         debug.textContent += msg.data;
richt@180
  1479
    }, false);
richt@180
  1480
richt@180
  1481
 // Send a control signal to mute the service audio
richt@180
  1482
richt@180
  1483
    var svcXhr = new XMLHttpRequest();
richt@180
  1484
    svcXhr.open("POST", services[0].url); // services[0].url and its
richt@180
  1485
                                          // subresources have been whitelisted for
richt@180
  1486
                                          // cross-site XHR use in this current
richt@180
  1487
                                          // browsing context.
richt@180
  1488
richt@180
  1489
    svcXhr.setRequestHeader('SOAPAction', 'urn:schemas-upnp-org:service:RenderingControl:1#SetMute');
richt@180
  1490
    svcXhr.setRequestHeader('Content-Type', 'text/xml; charset="utf-8";');
richt@180
  1491
richt@180
  1492
    svcXhr.onreadystatechange = function ( response ) {
richt@180
  1493
      if( response.readyState != 4 || response.status != 200 )
richt@180
  1494
        return;
richt@180
  1495
      debug.innerHTML += "&lt;br&gt;" + services[0].name + " response received: ";
richt@180
  1496
      debug.textContent += response.responseXML;
richt@180
  1497
    }
richt@180
  1498
richt@180
  1499
    // Service messaging to mute the provided service
richt@180
  1500
    var svcMsg = '&lt;?xml version="1.0" encoding="utf-8"?&gt;' +
richt@180
  1501
                 '&lt;s:Envelope s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" ' +
richt@180
  1502
                   'xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"&gt;' +
richt@180
  1503
                   '&lt;s:Body&gt;' +
richt@180
  1504
                     '&lt;u:SetMute xmlns:u="urn:schemas-upnp-org:service:RenderingControl:1"&gt;' +
richt@180
  1505
                       '&lt;InstanceID&gt;0&lt;/InstanceID&gt;' +
richt@180
  1506
                       '&lt;Channel&gt;Master&lt;/Channel&gt;' +
richt@180
  1507
                       '&lt;DesiredMute&gt;true&lt;/DesiredMute&gt;' +
richt@180
  1508
                     '&lt;/u:SetMute&gt;' +
richt@180
  1509
                   '&lt;/s:Body&gt;' +
richt@180
  1510
                 '&lt;/s:Envelope&gt;';
richt@180
  1511
richt@180
  1512
    svcXhr.send(svcMsg);
richt@180
  1513
    debug.innerHTML += "&lt;br&gt;" + services[0].name + " request sent: ";
richt@180
  1514
    debug.textContent += svcMsg;
richt@180
  1515
  }
richt@180
  1516
richt@180
  1517
  function errorCallback( error ) {
richt@180
  1518
    debug.innerHTML += "&lt;br&gt;An error occurred: " + error.code;
richt@180
  1519
  }
richt@180
  1520
&lt;/script&gt;</pre>
richt@180
  1521
          </div>
richt@180
  1522
richt@180
  1523
       </section>
richt@180
  1524
richt@180
  1525
    <section>
richt@180
  1526
      <h3>Acknowledgements</h3>
richt@180
  1527
richt@180
  1528
      <p>Thanks are expressed by the editor to the following individuals for their feedback on this specification to date (in alphabetical order):
richt@180
  1529
      <br /><br />
richt@180
  1530
      Gar Bergstedt, Lars-Erik Bolstad, Hari G Kumar, Bob Lund, Giuseppe Pascale, Marcin Simonides, Clarke Stevens, Christian S&ouml;derstr&ouml;m, Mark Vickers, ...</p>
richt@180
  1531
richt@180
  1532
      <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
  1533
      <br /></br />
richt@180
  1534
      CableLabs, Opera Software ASA, W3C Device APIs Working Group, W3C Web and TV Interest Group, ...</p>
richt@180
  1535
    </section>
richt@180
  1536
</body>
richt@180
  1537
</html>