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      Widget Updates
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</style><link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css" charset="utf-8" /></head>

  <body style="display: inherit;"><div class="head"><p><a href="http://www.w3.org/"><img width="72" height="48" alt="W3C" src="http://www.w3.org/Icons/w3c_home" /></a></p><h1 class="title" id="title">Widget Updates</h1><h2 id="w3c-working-draft-28-september-2010">W3C Working Draft 28 September 2010</h2><dl><dt>This version:</dt><dd><a href="http://www.w3.org/TR/2010/WD-widgets-updates-20100928/">http://www.w3.org/TR/2010/WD-widgets-updates-20100928/</a></dd><dt>Latest published version:</dt><dd><a href="http://www.w3.org/TR/widgets-updates/">http://www.w3.org/TR/widgets-updates/</a></dd><dt>Latest editor's draft:</dt><dd><a href="http://dev.w3.org/2006/waf/widgets-updates/">http://dev.w3.org/2006/waf/widgets-updates/</a></dd><dt>Previous version:</dt><dd><a href="http://www.w3.org/TR/2010/WD-widgets-updates-20100413/">http://www.w3.org/TR/2010/WD-widgets-updates-20100413/</a></dd><dt>Editors:</dt><dd><a href="http://datadriven.com.au/">Marcos Cáceres</a>, <a href="http://opera.com/">Opera Software</a></dd>
<dd><a href="http://richt.me/">Richard Tibbett</a>, <a href="http://opera.com/">Opera Software</a></dd>

<dd><a href="http://berjon.com/">Robin Berjon</a>, <a href="http://vodafone.com/">Vodafone</a></dd>
</dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2010 <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.eu/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p><hr /></div>

    <div id="abstract" class="introductory section"><h2>Abstract</h2>
      <p>
        This specification defines a process and a document format to allow a <a href="#dfn-user-agent" class="internalDFN">user agent</a> to update an installed widget package with
        a different version of a widget package. A widget cannot update itself; instead, a widget relies on the user agent to manage the
        update process. A user agent can perform an update over HTTP and from non-HTTP sources (e.g., directly from a device's memory
        card or hard disk).
      </p>
    </div><div id="sotd" class="introductory section"><h2>Status of This Document</h2><p><em>This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at http://www.w3.org/TR/.</em></p>

      <p class="note">
        <strong>Implementers should be aware that this document is not stable and should not be implemented.</strong> Implementers who are
        not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors
        interested in implementing this document before it eventually reaches the Candidate Recommendation stage should join the
        group's public mailing list and take part in the discussions.
      </p>
      <p>
        User agents that wish to extend this specification in any way are encouraged to discuss their extensions on a public forum, such as
        <a href="mailto:public-webapps@w3.org">public-webapps</a> so their extensions can be considered for standardization.
      </p>
      <p>

        This specification is part of the <a href="http://www.w3.org/2008/webapps/wiki/WidgetSpecs">Widgets Family of Specifications</a>.
      </p>
      <p>
        This Specification takes into account the <a href="http://www.w3.org/2009/03/widgets-pag/pagreport.html">recommendations</a> from the <a href="http://www.w3.org/2009/03/widgets-pag/">Widget Updates Patent Advisory Group</a> and considering <a href="http://www.w3.org/2009/03/widgets-pag/prior-art.html">the large set of prior art</a> the PAG found.
      </p>

    <p>This document was published by the <a href="http://www.w3.org/2008/webapps/">Web Applications WG</a> as a Working Draft. This document is intended to become a W3C Recommendation. If you wish to make comments regarding this document, please send them to <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a> (<a href="mailto:public-webapps-request@w3.org?subject=subscribe">subscribe</a>, <a href="http://lists.w3.org/Archives/Public/public-webapps/">archives</a>). All feedback is welcome.</p><p>Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.</p><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/42538/status" rel="disclosure">public list of any patent disclosures</a> made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the W3C Patent Policy</a>.</p></div><div id="toc" class="section"><h2 class="introductory">Table of Contents</h2><ul class="toc"><li class="tocline"><a href="#introduction" class="tocxref"><span class="secno">1. </span>

        Introduction
      </a></li><li class="tocline"><a href="#conformance" class="tocxref"><span class="secno">2. </span>Conformance</a></li><li class="tocline"><a href="#definitions" class="tocxref"><span class="secno">3. </span>
        Definitions
      </a><ul class="toc"><li class="tocline"><a href="#value-types" class="tocxref"><span class="secno">3.1 </span>
          Value types
        </a></li></ul></li><li class="tocline"><a href="#extensions-to-configuration-document" class="tocxref"><span class="secno">4. </span>
        Extensions to Configuration Document 
      </a><ul class="toc"><li class="tocline"><a href="#the-update-description-element" class="tocxref"><span class="secno">4.1 </span>

          The <code>update-description</code> Element
        </a><ul class="toc"><li class="tocline"><a href="#attributes" class="tocxref"><span class="secno">4.1.1 </span>
            Attributes
          </a></li><li class="tocline"><a href="#usage-example" class="tocxref"><span class="secno">4.1.2 </span>
            Usage example
          </a></li></ul></li><li class="tocline"><a href="#processing" class="tocxref"><span class="secno">4.2 </span>
          Processing <code>update-description</code> elements in the Configuration Document
        </a></li></ul></li><li class="tocline"><a href="#update-description-document" class="tocxref"><span class="secno">5. </span>

        Update Description Document
      </a><ul class="toc"><li class="tocline"><a href="#example-update-description-document" class="tocxref"><span class="secno">5.1 </span>
          Example Update Description Document
        </a></li><li class="tocline"><a href="#namespace" class="tocxref"><span class="secno">5.2 </span>
          Namespace
        </a></li><li class="tocline"><a href="#the-update-info-element" class="tocxref"><span class="secno">5.3 </span>
          The <code>update-info</code> Element
        </a><ul class="toc"><li class="tocline"><a href="#attributes-1" class="tocxref"><span class="secno">5.3.1 </span>

            Attributes
          </a></li><li class="tocline"><a href="#usage-example-1" class="tocxref"><span class="secno">5.3.2 </span>
            Usage example
          </a></li></ul></li><li class="tocline"><a href="#the-details-element" class="tocxref"><span class="secno">5.4 </span>
          The <code>details</code> Element
        </a><ul class="toc"><li class="tocline"><a href="#usage-example-2" class="tocxref"><span class="secno">5.4.1 </span>
            Usage example
          </a></li></ul></li></ul></li><li class="tocline"><a href="#acquiring-an-update-description-document" class="tocxref"><span class="secno">6. </span>

        Acquiring an Update Description Document
      </a></li><li class="tocline"><a href="#processing-an-update-description-document" class="tocxref"><span class="secno">7. </span>
        Processing an Update Description Document
      </a></li><li class="tocline"><a href="#verifying-and-installing-an-update" class="tocxref"><span class="secno">8. </span>
        Verifying and Installing an Update
      </a></li><li class="tocline"><a href="#security-considerations" class="tocxref"><span class="secno">9. </span>
        Security Considerations
      </a></li><li class="tocline"><a href="#design-goals-and-requirements" class="tocxref"><span class="secno">A. </span>
        Design Goals and Requirements
      </a></li><li class="tocline"><a href="#acknowledgements" class="tocxref"><span class="secno">B. </span>

        Acknowledgements
      </a></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">C. </span>References</a><ul class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">C.1 </span>Normative references</a></li><li class="tocline"><a href="#informative-references" class="tocxref"><span class="secno">C.2 </span>Informative references</a></li></ul></li></ul></div>
    
    <div class="informative section" id="introduction">
      
<!-- OddPage -->
<h2><span class="secno">1. </span>
        Introduction
      </h2><p><em>This section is non-normative.</em></p>

      <p>
        There are a multitude of reasons why authors might want to update a widget including addressing security vulnerabilities, making
        performance enhancements, and adding new features. Sometimes authors may even want to revert back to a previous version of a
        widget, if it is found that a newly deployed version of a widget contains issues or vulnerabilities.
      </p>
      <p>
        To facilitate the process of updating widgets, this specification introduces an XML element, called
        <code>update-description</code>, that is included into a <a href="#dfn-configuration-document" class="internalDFN">configuration document</a> of a widget. This specificaiton also introduces a new XML vocabulary, called an <a href="#dfn-update-description-document" class="internalDFN">update
        description document</a>. The <code>update-description</code> element provides an author with a means to point to an <a href="#dfn-update-description-document" class="internalDFN">update description
      document</a>. An <a href="#dfn-update-description-document" class="internalDFN">update description document</a> is metadata about an widget update including:
      </p>

      <ul>
        <li>
          <p>
            a means to describe the purpose of the update.
          </p>
        </li>
        <li>
          <p>
            a means to indicate the version number of the <a href="#dfn-potential-update" class="internalDFN">potential update</a>.
          </p>

        </li>
        <li>
          <p>
            a link to where the updated widget package can be retrieved from.
          </p>
        </li>
      </ul>
      <p>
        If a <a href="#dfn-user-agent" class="internalDFN">user agent</a> determines, via the <a>strategies defined in this specification</a>, that two widget packages are not the
        same version, and if the user consents, the <a href="#dfn-user-agent" class="internalDFN">user agent</a> will attempt to replace the currently installed widget package with a
        <a href="#dfn-potential-update" class="internalDFN">potential update</a>. Updates are designed to retain any locally stored data, so to protect end-users from losing data that a
        widget may have stored at runtime.
      </p>

      <p>This specification also defines the rules that govern the interactions between the user agent, the <a href="#dfn-update-description-document" class="internalDFN">update description document</a>, and the updated widget. </p>
    </div>
    <div id="conformance" class="section">
<!-- OddPage -->
<h2><span class="secno">2. </span>Conformance</h2><p>As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.</p>
<p>The key words <em class="rfc2119" title="must">must</em>, <em class="rfc2119" title="must not">must not</em>, <em class="rfc2119" title="required">required</em>, <em class="rfc2119" title="should">should</em>, <em class="rfc2119" title="should not">should not</em>, <em class="rfc2119" title="recommended">recommended</em>, <em class="rfc2119" title="may">may</em>, and <em class="rfc2119" title="optional">optional</em> in this specification are to be interpreted as described in [<cite><a class="bibref" rel="biblioentry" href="#bib-RFC2119">RFC2119</a></cite>].</p>

      <p>
        This specification defines conformance requirements for a single class of product: <a title="user agent" href="#dfn-user-agent" class="internalDFN">user agents</a>.
      </p>
    </div>
    <div id="definitions" class="section">
      
<!-- OddPage -->
<h2><span class="secno">3. </span>
        Definitions
      </h2>

      <p>
        The concepts of a <dfn class="external" id="dfn-widget-package">widget package</dfn> and a <dfn class="external" id="dfn-configuration-document">configuration document</dfn> are defined in the [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>] specification.
      </p>
      <p>
        A <dfn id="dfn-user-agent">user agent</dfn> is an implementation of this specification that also implements the [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>] specification and its
        dependencies.
      </p>

      <p>
        An <dfn id="dfn-installed-widget">installed widget</dfn> is a <span>widget package</span> that has been correctly installed on a <a href="#dfn-user-agent" class="internalDFN">user agent</a>.
      </p>
      <p>
        An <dfn id="dfn-update-description-source">update description source</dfn> is the URI referenced by the <code>href</code> attribute of an
        <code>update-description</code> element of an <a title="installed widget" href="#dfn-installed-widget" class="internalDFN">installed widget's</a> <a href="#dfn-configuration-document" class="internalDFN">configuration document</a>.
      </p>

      <p>
        An <dfn id="dfn-update-description-document">update description document</dfn> is an [<cite><a class="bibref" rel="biblioentry" href="#bib-XML10">XML10</a></cite>] document that has a <code>update-info</code> element at its root.
      </p>
      <p>
        An <dfn id="dfn-update-source">update source</dfn> is the URI referenced by the <code>src</code> attribute of an <code>update-info</code> element of an
        <a href="#dfn-update-description-document" class="internalDFN">update description document</a>.
      </p>

      <p>
        A <dfn id="dfn-potential-update">potential update</dfn> is a resource acquired via HTTP from an <a href="#dfn-update-source" class="internalDFN">update source</a> or from local media.
      </p>
      <p>
        The <dfn id="dfn-widget-update-process">widget update process</dfn> is a multi-step process whereby a <a href="#dfn-user-agent" class="internalDFN">user agent</a> acquires a <a href="#dfn-potential-update" class="internalDFN">potential update</a>,
        performs the <a href="#dfn-rule-for-verifying-a-widget-update" class="internalDFN">rule for verifying a widget update</a>, and then proceeds to <a href="#dfn-install-the-widget-package" class="internalDFN">install the widget package</a>.
      </p>

      <p>
        The <dfn id="dfn-identity">identity</dfn> of a <a href="#dfn-widget-package" class="internalDFN">widget package</a> is determined by the <code>id</code> attribute of the <code>widget</code>
        element declared by an author in the <a href="#dfn-configuration-document" class="internalDFN">configuration document</a> of a <a href="#dfn-widget-package" class="internalDFN">widget package</a>.
      </p>

      <p>
        The <dfn id="dfn-version">version</dfn> of a <a href="#dfn-widget-package" class="internalDFN">widget package</a> is determined by the <code>version</code> attribute of the <code>widget</code>
        element declared by an author in the <a href="#dfn-configuration-document" class="internalDFN">configuration document</a> of a <a href="#dfn-widget-package" class="internalDFN">widget package</a>.
      </p>

      <p>
        An <dfn id="dfn-incumbent-widget">incumbent widget</dfn> is an <a href="#dfn-installed-widget" class="internalDFN">installed widget</a> that is determined to have the same <a href="#dfn-identity" class="internalDFN">identity</a> as the
        <a href="#dfn-potential-update" class="internalDFN">potential update</a>.
      </p>
      <p>

        An <a href="#dfn-installed-widget" class="internalDFN">installed widget</a> is said to be <dfn id="dfn-up-to-date">up-to-date</dfn> if a <a href="#dfn-user-agent" class="internalDFN">user agent</a> determins that an <a href="#dfn-incumbent-widget" class="internalDFN">incumbent widget</a> does not need
        updating.
      </p>
      <p>

        A <dfn id="dfn-failure-notification">failure notification</dfn> is an optional message emitted by the <a href="#dfn-user-agent" class="internalDFN">user agent</a> to indicate to the user that a <a>widget
        update</a> has failed.
      </p>
      <p>
        Note: This specification does not define the means or format of a <a href="#dfn-failure-notification" class="internalDFN">failure notification</a>, which is left up to implementers.
      </p>

      <div id="value-types" class="section">
        <h3><span class="secno">3.1 </span>
          Value types
        </h3>
        <p>
          The <a class="externalDFN" title="space character">space characters</a>, <a class="externalDFN">valid URI</a>, and <a class="externalDFN">valid version-tag</a> are defined in the <cite>Widget Packaging and Configuration</cite> specification
          [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>].
        </p>

      </div>
    </div>
    <div id="extensions-to-configuration-document" class="section">
      
<!-- OddPage -->
<h2><span class="secno">4. </span>
        Extensions to Configuration Document 
      </h2>
      As stated above, this specification introduces a new element to the  <a href="#dfn-configuration-document" class="internalDFN">configuration document</a> defined in [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>]. This new element is defined below.
      <div id="the-update-description-element" class="section">

<h3><span class="secno">4.1 </span>
          The <code>update-description</code> Element
        </h3>
        <p>
          The <code>update-description</code> element points, via the <code>href</code> attribute, to an <a href="#dfn-update-description-document" class="internalDFN">update description
          document</a>.
        </p>

        <p>
          The <code>update-description</code> element is in the <code>http://www.w3.org/ns/widgets</code> namespace as defined in
          [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>].
        </p>
        <dl class="eldef">
          <dt>

            Context in which this element is  used:
          </dt>
          <dd>
            As a child of the <code>widget</code> element defined in the [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>] specification.
          </dd>
          <dt>
            Content model:
          </dt>

          <dd>
            Empty.
          </dd>
          <dt>
            Occurrences:
          </dt>
          <dd>
            Zero or one.
          </dd>
          <dt>

            Expected children:
          </dt>
          <dd>
            None.
          </dd>
          <dt>
            Localizable via <code>xml:lang</code>:
          </dt>
          <dd>

            No.
          </dd>
        </dl>
        <div id="attributes" class="section">
          <h4><span class="secno">4.1.1 </span>
            Attributes
          </h4>
          <dl class="attrs">
            <dt>

              <code><dfn id="dfn-href">href</dfn></code>
            </dt>
            <dd>
              A <span>URI attribute</span> that points to the location of an <a href="#dfn-update-description-document" class="internalDFN">update description document</a>.
            </dd>
          </dl>

        </div>
        <div id="usage-example" class="section">
          <h4><span class="secno">4.1.2 </span>
            Usage example
          </h4>
          <p>
            This example shows the expected usage of the <code>update-description</code> element.
          </p>

<pre class="example">
&lt;widget xmlns  ="http://www.w3.org/ns/widgets" 
        id     ="http://example.com/my-widget" 
        version="1.0"&gt;

<span class="hilite">&lt;update-description 
   href="http//example.com/update?widget=my-widget&amp;amp;version=1.0"/&gt;</span>

&lt;/widget&gt;</pre>
        </div>
      </div>
      <div id="processing" class="section">
        <h3><span class="secno">4.2 </span>

          Processing <code>update-description</code> elements in the Configuration Document
        </h3>
        <p>This section describes the <dfn id="dfn-algorithm-for-processing-the-update-description-element">algorithm for processing the update-description element</dfn>. </p>
        <ol>
          <li>A <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> add the following to the <a href="http://www.w3.org/TR/widgets/#table-of-configuration-defaults">Table of Configuration Defaults</a> [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>] during Step 3 - Set the Configuration defaults. </li>

        </ol>
        <table summary="The configuration defaults that a user agent must set prior to instantiation." class="simple">
          <caption>
            Table of Configuration Defaults (addendum)
          </caption>
          <thead>
            <tr>
              <th scope="col">
                Variable
              </th>

              <th scope="col">
                Type
              </th>
              <th scope="col">
                Default Value
              </th>
              <th scope="col">
                Overridden in
              </th>
              <th scope="col">

                Description
              </th>
            </tr>
          </thead>
          <tbody><tr>
            <th scope="row">
              <dfn id="dfn-update-href"><var>update href</var></dfn> 
            </th>
            <td>

              URI
            </td>
            <td>
              <code>null</code> 
            </td>
            <td>
              <a href="#processing">Processing <code>update-description</code> elements in the Configuration Document</a> 
            </td>

            <td>
              The URI for where an update description can be downloaded, corresponding to the <code>update-description</code> element's
              <code>href</code> attribute.
            </td>
          </tr>
        </tbody></table>
        <p> </p>

        <ol start="2">
          <li> During  <a href="http://www.w3.org/TR/widgets/#step-7--process-the-configuration-docume">Step 7 - Process the Configuration Document</a>, if this is not the first <a><code>update-description</code></a> element, then the <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> <a>ignore</a> this
          element and its descendants.          </li>

          <li>If this is the first <a><code>update-description</code></a> element and the <code>href</code> attribute is used, and it is a
            <a>valid uri</a>, then let <a href="#dfn-update-href" class="internalDFN"><var>update href</var></a> be the value of the <code>href</code> attribute.
          Otherwise, this elements is in error and the user agent <em class="rfc2119" title="must">must</em> ignore this element. </li>

        </ol>
      </div>
</div>
    <div id="update-description-document" class="section">
      
<!-- OddPage -->
<h2><span class="secno">5. </span>
        Update Description Document
      </h2>
      <p>
        Within an <a href="#dfn-update-description-document" class="internalDFN">update description document</a> an author declares, amongst other things, what's new or different in the
        <a href="#dfn-potential-update" class="internalDFN">potential update</a>, the version that the widget will be updated to, and the URI from where the <a href="#dfn-user-agent" class="internalDFN">user agent</a> can retrieve
        the <a href="#dfn-potential-update" class="internalDFN">potential update</a> (the <a href="#dfn-update-source" class="internalDFN">update source</a>).
      </p>

      <p>
        The purpose of the <a href="#dfn-update-description-document" class="internalDFN">update description document</a> is to provide the details about a <a href="#dfn-potential-update" class="internalDFN">potential update</a>, including a
        pointer to a HTTP resource that will act as the <a href="#dfn-potential-update" class="internalDFN">potential update</a>.
      </p>
      <p>
        In order for a <a href="#dfn-user-agent" class="internalDFN">user agent</a> to retrieve and process an <a href="#dfn-update-description-document" class="internalDFN">update description document</a>, an author must initially declare a
        valid URI for the <code>update-description</code> element in the installed <a href="#dfn-configuration-document" class="internalDFN">configuration document</a> (e.g.
        <code>&lt;update-description href="https://example.com/myWidget/updates"/&gt;</code>).
      </p>

      <div id="example-update-description-document" class="section">
        <h3><span class="secno">5.1 </span>
          Example Update Description Document
        </h3>
        <p>
          Below is an example of a typical <a href="#dfn-update-description-document" class="internalDFN">update description document</a>.
        </p>
<pre class="example">
<span class="hilite">&lt;update-info xmlns   = "http://www.w3.org/ns/widgets"
             src     = "https://w.example.com/2.1/RC/app.wgt"
             version = "RC2.1"&gt;

  &lt;details&gt;
    Now supporting X, Y and Z features!
  &lt;/details&gt;
&lt;/update-info&gt;</span></pre>
      </div>
      <div id="namespace" class="section">
        <h3><span class="secno">5.2 </span>
          Namespace
        </h3>

        <p>
          All elements defined to be used in an <a href="#dfn-update-description-document" class="internalDFN">update description document</a> are in the <code>http://www.w3.org/ns/widgets</code>
          namespace as defined in [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>].
        </p>
      </div>
      <div id="the-update-info-element" class="section">

        <h3><span class="secno">5.3 </span>
          The <code>update-info</code> Element
        </h3>
        <p>
          The <code>update-info</code> element is intended to provide metadata about the <a href="#dfn-potential-update" class="internalDFN">potential update</a>. In addition, it serves as
          a container for the other elements; as such, it <em class="ct1">must</em> be used.
        </p>

        <dl class="eldef">
          <dt>
            Context in which this element <em class="rfc2119" title="may">may</em> be used:
          </dt>
          <dd>
            The root element of an <a href="#dfn-update-description-document" class="internalDFN">update description document</a>.
          </dd>

          <dt>
            Content model:
          </dt>
          <dd>
            Zero or more <a class="internalDFN"><code>details</code></a> elements.
          </dd>
          <dt>
            Occurrences:
          </dt>

          <dd>
            Exactly one, at the root element of the document.
          </dd>
          <dt>
            Expected children:
          </dt>
          <dd>
            <a><code>details</code></a>.
          </dd>
          <dt>

            Localizable via <code>xml:lang</code>:
          </dt>
          <dd>
            No.
          </dd>
        </dl>
        <div id="attributes-1" class="section">
          <h4><span class="secno">5.3.1 </span>

            Attributes
          </h4>
          <dl class="attrs">
            <dt>
              <code>version</code>
            </dt>
            <dd>
              A <span>valid version tag</span> that denotes the version number of the <a href="#dfn-potential-update" class="internalDFN">potential update</a>.
            </dd>

            <dt>
              <code>src</code>
            </dt>
            <dd>
              A <span>valid URI</span> that references a <a href="#dfn-potential-update" class="internalDFN">potential update</a>. Over the wire, the potential update <em class="rfc2119" title="must">must</em> be labeled with
              a correct widget media type (i.e. <code>application/widget</code>).
            </dd>

          </dl>
        </div>
        <div id="usage-example-1" class="section">
          <h4><span class="secno">5.3.2 </span>
            Usage example
          </h4>
          <p>
            The example below shows how the <code>update-info</code> element can be used.
          </p>

<pre class="example">
<span class="hilite">&lt;update-info xmlns="http://www.w3.org/ns/widgets"
             src="http://sometld/somewidget_0_3_BETA.wgt"
             version="BETA 0.3"&gt;</span>
           
<span class="hilite">&lt;/update-info&gt;</span></pre>
        </div>
      </div>
      <div id="the-details-element" class="section">
        <h3><span class="secno">5.4 </span>
          The <code>details</code> Element
        </h3>

        <p>
          The <code>details</code> element represents a human-readable description of what differentiates this <a href="#dfn-potential-update" class="internalDFN">potential update</a> from
          other versions.
        </p>
        <dl class="eldef">
          <dt>
            Context in which this element can be used:
          </dt>

          <dd>
            Inside a <code>update-info</code> element.
          </dd>
          <dt>
            Content model:
          </dt>
          <dd>
            Anything.
          </dd>

          <dt>
            Occurrences:
          </dt>
          <dd>
            Zero or more.
          </dd>
          <dt>
            Expected children:
          </dt>
          <dd>

            Anything.
          </dd>
          <dt>
            Localizable via <code>xml:lang</code>:
          </dt>
          <dd>
            Yes.
          </dd>
        </dl>

        <div id="usage-example-2" class="section">
          <h4><span class="secno">5.4.1 </span>
            Usage example
          </h4>
          <p>
            The example below shows how the <code>details</code> element can be used.
          </p>
<pre class="example">

&lt;update-info xmlns="http://www.w3.org/ns/widgets"
             src="http://foo.com/widget.wgt"
             version="1.3.1"&gt;
  <span class="hilite">&lt;details&gt;
    This update tries to make 2010 a little bit less like "1984".
  &lt;/details&gt;</span>
&lt;/update-info&gt;</pre>
        </div>
      </div>
</div>
    <div id="acquiring-an-update-description-document" class="section">

      
<!-- OddPage -->
<h2><span class="secno">6. </span>
        Acquiring an Update Description Document
      </h2>
      <p>
        The <dfn id="dfn-authoritative-update-uri">authoritative update URI</dfn> is the <code>update source</code> of an installed widget's <a href="#dfn-configuration-document" class="internalDFN">configuration
        document</a>.
      </p>

      <p>
        A <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> support the capability to acquire an <a href="#dfn-update-description-document" class="internalDFN">update description document</a> over HTTP protocols. For non-HTTP
        protocols, UAs should act in equivalent ways.
      </p>
      <p>
        It is expected that user agents will perform a <a href="#dfn-widget-update-process" class="internalDFN">widget update process</a> asynchronously and periodically check for any available
        updates. The timing of any <a href="#dfn-widget-update-process" class="internalDFN">widget update process</a> is an implementation detail left to the discretion of the implementer (e.g.
        once a day or once a week).
      </p>

      <p>
        To check for updates to a widget, the <a href="#dfn-user-agent" class="internalDFN">user agent</a> issues a HTTP request towards the <a href="#dfn-authoritative-update-uri" class="internalDFN">authoritative update URI</a>.
      </p>
      <p>
        The <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="should">should</em> send the last known <var>ETag</var> response value, if available, in an <var>If-None-Match</var>

        header.
      </p>
      <p>
        The <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="should">should</em> send an <var>If-Modified-Since</var> header indicating the time of the last check for an update from
        the <a href="#dfn-user-agent" class="internalDFN">user agent</a>.
      </p>

      <p>
        If the widget is displaying localized content, the <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="should">should</em> send an <var>Accept-Encoding</var> header representing
        the widget's locale.
      </p>
      <p>
        As data is received, the <a href="#dfn-user-agent" class="internalDFN">user agent</a> will then act as follows.
      </p>

      <p>
        The <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="should">should</em> ignore any <var>Cache-Control</var> or <var>Pragma</var> header with a value of <code>no-cache</code>.
      </p>

      <p>
        The <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="should">should</em> honor the value of any <var>Expires</var> header when scheduling the next <a href="#dfn-widget-update-process" class="internalDFN">widget update process</a>
        for the current <a href="#dfn-installed-widget" class="internalDFN">installed widget</a>.
      </p>

      <p>
        HTTP 200 OK responses with a <var>Content-Type</var> header specifying the type <code>application/xml</code> <em class="rfc2119" title="must">must</em> be processed
        according to the rules defined in <a href="#processing-an-update-description-document">Processing an Update Description Document</a>.
      </p>
      <p>

        HTTP 200 OK responses that have a <var>Content-Type</var> other than <code>application/xml</code> <em class="rfc2119" title="must">must</em> cause the <a href="#dfn-user-agent" class="internalDFN">user agent</a>
        to <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate the widget update</a>.
      </p>

      <p>
        HTTP 204 No Content, 205 Reset Content, and 304 Not Modified responses are equivalent to 200 OK responses with a
        <var>Content-Type</var> other than <code>application/xml</code>.
      </p>
      <p>
        Other HTTP response codes in the 2xx range <em class="rfc2119" title="must">must</em> <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate the widget update</a>. They are, however, likely to indicate an error
        has occurred somewhere and <em class="rfc2119" title="may">may</em> cause the <a href="#dfn-user-agent" class="internalDFN">user agent</a> to emit a warning.
      </p>

      <p>
        HTTP 301 Moved Permanently, 302 Found, 303 See Other, and 307 Temporary Redirect responses <em class="rfc2119" title="must">must</em> cause the <a href="#dfn-user-agent" class="internalDFN">user agent</a> to
        reconnect using the new server specified URL instead of the previously specified URL.
      </p>
      <p>
        HTTP 305 Use Proxy, 401 Unauthorized, and 407 Proxy Authentication Required should be treated transparently as for any other
        subresource.
      </p>
      <p>

        Any other HTTP response code not listed here, and any network error that prevents the HTTP connection from being established in the
        first place (e.g. DNS errors), <em class="rfc2119" title="must">must</em> cause the <a href="#dfn-user-agent" class="internalDFN">user agent</a> to <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate the widget update</a>.
      </p>
      <p> 
        
      </p>
    </div>
    <div id="processing-an-update-description-document" class="section">

      
<!-- OddPage -->
<h2><span class="secno">7. </span>
        Processing an Update Description Document
      </h2>
      <p>
        A <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> assume the following defaults prior to processing an <a href="#dfn-update-description-document" class="internalDFN">update description document</a>:
      </p>

      <table summary="The update configuration defaults that a user agent must set prior to update description document processing." class="simple">
        <caption>
          <dfn id="dfn-update-defaults">Update Defaults</dfn>
        </caption>
        <tbody>
          <tr>
            <th scope="col">
              Variable
            </th>

            <th scope="col">
              Type
            </th>
            <th scope="col">
              Default value
            </th>
            <th scope="col">
              Description
            </th>
          </tr>

          <tr>
            <th scope="row">
              <var>update-source</var> 
            </th>
            <td>
              URI
            </td>
            <td>
              <code>null</code> 
            </td>

            <td> 
              
            </td>
          </tr>
          <tr>
            <th scope="row">
              <var>version-tag</var> 
            </th>
            <td>
              DOMString
            </td>

            <td>
              null
            </td>
            <td> 
              
            </td>
          </tr>
          <tr>
            <th scope="row">
              details
            </th>

            <td>
              DOMString
            </td>
            <td>
              null
            </td>
            <td> 
              
            </td>
          </tr>
        </tbody>

      </table>
      <p>
        A <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> process an <a href="#dfn-update-description-document" class="internalDFN">update description document</a> according to the <a href="#dfn-rule-for-processing-an-update-description-document" class="internalDFN">rule for processing an update
        description document</a>.
      </p>

      <p>
        The following processing model is written with more concern for clarity over efficiency. As such, a <a href="#dfn-user-agent" class="internalDFN">user agent</a> can optimize
        the processing model so long as the end result is indistinguishable from the result that would be obtained by the following the
        specification.
      </p>
      <p>
        The term <dfn id="in-error">in error</dfn>, typically used on an element or attribute, means that the element, attribute, or other construct
        does not conform to the rules of this specification. Rules for exactly how a user agent needs to treat the erroneous construct are
        always given when the term is used.
      </p>
      <p>

        When an <dfn id="dfn-invalid-update-description-document">invalid update description document</dfn> is determined, the <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> terminate the current <a href="#dfn-widget-update-process" class="internalDFN">widget
        update process</a>.
      </p>
      <p>
        The <dfn id="dfn-rule-for-processing-an-update-description-document">rule for processing an update description document</dfn> is defined as follows:
      </p>

      <ol class="rule">
        <li>
          Let <var>doc</var> be the result of parsing the acquired <a href="#dfn-update-description-document" class="internalDFN">update description document</a> as a [<cite><a class="bibref" rel="biblioentry" href="#bib-DOM-LEVEL-3-CORE">DOM-LEVEL-3-CORE</a></cite>]
          <code>Document</code> using a [<cite><a class="bibref" rel="biblioentry" href="#bib-XML-NAMES">XML-NAMES</a></cite>]-aware parser. If the document is not well-formed [<cite><a class="bibref" rel="biblioentry" href="#bib-XML10">XML10</a></cite>], then treat this as an
          <a href="#dfn-invalid-update-description-document" class="internalDFN">invalid update description document</a>.
        </li>

        <li>
          Let <var>root element</var> be the <code>documentElement</code> of <var>doc</var>.
        </li>
        <li>
          If the <var>root element</var> is not a <code>update-info</code> element in the widget namespace, then treat this <a href="#dfn-update-description-document" class="internalDFN">update
          description document</a> as an <a href="#dfn-invalid-update-description-document" class="internalDFN">invalid update description document</a>.
        </li>

        <li>
          If the <var>root element</var> is a <code>update-info</code> element: 
          <ol class="rule">
            <li>
              If the <code>version</code> attribute was used, and it is a <span>valid version-tag</span>, then let <var>version-tag</var>

              be the value of <span><code>version</code></span>.
            </li>
            <li>
              If no <code>version</code> attribute was used, or the value was <a href="#in-error" class="internalDFN">in error</a>, treat this as an <a href="#dfn-invalid-update-description-document" class="internalDFN">invalid update
              description document</a>.
            </li>

            <li>
              If the <code>src</code> attribute was used, and it is a <span><span>valid URI</span></span>, then let
              <var>update-source</var> be the value of <code>src</code>.
            </li>
            <li>

              If no <code>src</code> attribute was used, or the value was <a href="#in-error" class="internalDFN">in error</a>, treat this as an <a href="#dfn-invalid-update-description-document" class="internalDFN">invalid update description
              document</a>.
            </li>
          </ol>
        </li>
        <li>
          For any child element of the <var>root element</var>:
        </li>

        <li style="list-style: none">
          <ol>
            <li>
              If the child element is a <code>details</code> element: 
              <ol class="rule">
                <li>
                  If this is not the first <code>details</code> element, then the element is <a href="#in-error" class="internalDFN">in error</a> and <em class="rfc2119" title="must">must</em> be
                  <span>ignored</span>.
                </li>

                <li>
                  Let <var>details</var> be the result of applying the <a class="externalDFN" title="rule for getting text content">rule for getting text content</a> [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>] to this element.
                </li>
              </ol>
            </li>

            <li>
              Otherwise it <em class="rfc2119" title="must">must</em> be ignored.
            </li>
          </ol>
        </li>
      </ol>
      <p> 
        
      </p>

    </div>
    <div id="verifying-and-installing-an-update" class="section">
      
<!-- OddPage -->
<h2><span class="secno">8. </span>
        Verifying and Installing an Update
      </h2>
      <p>When a <a href="#dfn-user-agent" class="internalDFN">user agent</a> is to <dfn id="dfn-install-the-widget-package">install the widget package</dfn> it <em class="rfc2119" title="must">must</em> remove any <a href="#dfn-incumbent-widget" class="internalDFN">incumbent widget</a> and
      add the <a href="#dfn-potential-update" class="internalDFN">potential update</a> as an <a href="#dfn-installed-widget" class="internalDFN">installed widget</a>. </p>

      <p>When a <a href="#dfn-user-agent" class="internalDFN">user agent</a> is to <dfn id="dfn-terminate-the-widget-update">terminate the widget update</dfn> the <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> terminate the current <a href="#dfn-widget-update-process" class="internalDFN">widget
        update process</a>. The <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="may">may</em> emit a <a href="#dfn-failure-notification" class="internalDFN">failure notification</a> warning that the widget update has been
      terminated. </p>

      <p>
        To verify and install a <a href="#dfn-potential-update" class="internalDFN">potential update</a> the <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> apply the <a href="#dfn-rule-for-verifying-a-widget-update" class="internalDFN">rule for verifying a widget update</a>.
      </p>
      <p>

        The <dfn id="dfn-rule-for-verifying-a-widget-update">rule for verifying a widget update</dfn> enables a <a href="#dfn-user-agent" class="internalDFN">user agent</a> to match and verify a <a href="#dfn-potential-update" class="internalDFN">potential update</a> -
        acquired via HTTP or from local media - with an installed <a href="#dfn-widget-package" class="internalDFN">widget package</a> and is defined as follows:
      </p>
      <ol class="rule">

        <li>
          Apply the <a class="externalDFN" title="steps for processing a widget package">steps for processing a widget package</a> [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>] to the obtained
          <a href="#dfn-potential-update" class="internalDFN">potential update</a>. 
          <ul class="rule">
            <li>
              If an <a class="externalDFN" title="invalid widget package">invalid widget package</a> [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS">WIDGETS</a></cite>] is detected, the <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate
              the widget update</a>.
            </li>

          </ul>
        </li>
        <li>
          If an <a href="#dfn-incumbent-widget" class="internalDFN">incumbent widget</a> could not be found then skip the rest of this rule and <a href="#dfn-install-the-widget-package" class="internalDFN">install the widget package</a>.
        </li>
        <li>
          If the <a href="#dfn-incumbent-widget" class="internalDFN">incumbent widget</a> has the same <a href="#dfn-version" class="internalDFN">version</a> as the <a href="#dfn-potential-update" class="internalDFN">potential update</a> then the <a href="#dfn-installed-widget" class="internalDFN">installed widget</a> is
          <a href="#dfn-up-to-date" class="internalDFN">up-to-date</a> and the <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate the widget update</a>.
        </li>

        <li>
          If the <a href="#dfn-potential-update" class="internalDFN">potential update</a> is determined to be a <a class="externalDFN" title="digitally-signed widget package">digitally-signed widget package</a> when applying the rules for <a class="externalDFN" title="rules for signature validation">signature validation</a> [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS-DIGSIG">WIDGETS-DIGSIG</a></cite>] then the <a href="#dfn-user-agent" class="internalDFN">user agent</a> will act as
          follows: 
          <ul class="rule">

            <li>
              If the <a href="#dfn-incumbent-widget" class="internalDFN">incumbent widget</a> is also determined to be a <a class="externalDFN" title="digitally-signed widget package">digitally-signed widget package</a> when applying the rules for <a class="externalDFN" title="rules for signature validation">signature validation</a> [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS-DIGSIG">WIDGETS-DIGSIG</a></cite>] then the <a href="#dfn-user-agent" class="internalDFN">user agent</a> will act as
              follows: 
              <ol class="rule">

                <li>
                  Let <var>update_digsigs</var> be an enumerated list of all the digital signatures contained within the <a href="#dfn-potential-update" class="internalDFN">potential
                  update</a> obtained according to the rule to <a class="externalDFN" title="rules for locating and processing digital signatures">locate signature files in a widget package</a>
                  [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS-DIGSIG">WIDGETS-DIGSIG</a></cite>].
                </li>

                <li>
                  If any of the elements within <var>update_digsigs</var> were determined to be <a href="#in-error" class="internalDFN">in error</a> then <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate the
                  widget update</a>.
                </li>
                <li>
                  Let <var>incumbent_digsigs</var> be an enumerated list of all the digital signatures contained within the <a href="#dfn-incumbent-widget" class="internalDFN">incumbent
                  widget</a> obtained according to the rule to <a class="externalDFN" title="rules for locating and processing digital signatures">locate signature files in a widget package</a>

                  [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS-DIGSIG">WIDGETS-DIGSIG</a></cite>].
                </li>
                <li>
                  If any of the elements within <var>incumbent_digsigs</var> were determined to be <a href="#in-error" class="internalDFN">in error</a> then <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate the
                  widget update</a>. This is, however, likely to indicate an error has occurred somewhere in the installed <a href="#dfn-widget-package" class="internalDFN">widget
                  package</a> processing and may cause the <a href="#dfn-user-agent" class="internalDFN">user agent</a> to emit a warning.
                </li>

              </ol>
              <p>
                Note: The decision of which (if any) <a class="externalDFN">distributor signatures</a> are to be validated and whether the <a class="externalDFN">author signature</a> is to be validated is out of scope [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS-DIGSIG">WIDGETS-DIGSIG</a></cite>].
              </p>
              <ol start="5" class="rule">

                <li>
                  For each <var>update_signature</var> to be validated in <var>update_digsigs</var>: 
                  <ol class="rule">
                    <li>
                      Let <var>digSigsMatch</var> be the result of comparing the <code>dsp:Identifier</code> value [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS-DIGSIG">WIDGETS-DIGSIG</a></cite>] from <var>update_signature</var> with the same
                      value obtained from the associated <var>incumbent_signature</var> within <var>incumbent_digsigs</var>. 
                    </li>

                    <li>
                      If <var>digSigsMatch</var> is false then <a href="#dfn-terminate-the-widget-update" class="internalDFN">terminate the widget update</a>.
                    </li>
                  </ol>
                </li>
              </ol>
            </li>

          </ul>
        </li>
        <li>
          The <a href="#dfn-user-agent" class="internalDFN">user agent</a> <em class="rfc2119" title="must">must</em> <a href="#dfn-install-the-widget-package" class="internalDFN">install the widget package</a>.
        </li>
      </ol>

    </div>
    <div id="security-considerations" class="section">
      
<!-- OddPage -->
<h2><span class="secno">9. </span>
        Security Considerations
      </h2>
      <p>
        Because an <a href="#dfn-update-description-document" class="internalDFN">update description document</a> is not self-contained, it is conceivable that the update model could be subject to a
        man-in-the-middle attack, as with any unencrypted requests performed over [<cite><a class="bibref" rel="biblioentry" href="#bib-HTTP11">HTTP11</a></cite>]. For this reason, it is <em class="rfc2119" title="recommended">recommended</em> that, for
        widgets that have not been digitally signed, updates are always performed over [<cite><a class="bibref" rel="biblioentry" href="#bib-HTTP-TLS">HTTP-TLS</a></cite>].
      </p>

      <p>
        Another means of protection is for authors to always digitally sign their widget resources. During an update, the <a href="#dfn-user-agent" class="internalDFN">user agent</a>
        will then validate the signature before installation, ensuring that a widget resource's identity and integrity was maintained
        over the network.
      </p>
      <p>
        Without the availability of a digitally signed <a href="#dfn-installed-widget" class="internalDFN">installed widget</a>, it is extremely easy to overwrite a widget resource with
        another (potentially malicious) widget resource. Therefore it is <em class="rfc2119" title="recommended">recommended</em> that a <a href="#dfn-user-agent" class="internalDFN">user agent</a> only allow updates to a
        signed <a href="#dfn-installed-widget" class="internalDFN">installed widget</a> or to a non-signed <a href="#dfn-installed-widget" class="internalDFN">installed widget</a> only from a <a href="#dfn-potential-update" class="internalDFN">potential update</a> obtained via its
        <a href="#dfn-authoritative-update-uri" class="internalDFN">authoritative update URI</a>.
      </p>

    </div>
    <div class="appendix informative section" id="design-goals-and-requirements">
      
<!-- OddPage -->
<h2><span class="secno">A. </span>
        Design Goals and Requirements
      </h2><p><em>This section is non-normative.</em></p>
      <p>
        This document addresses the <a href="http://www.w3.org/TR/widgets-reqs/#remote-and-local-updates">Remote and Local Updates</a> the requirement of the 30 April
        2009 Working Draft of the <cite>Widgets 1.0: Requirements Document</cite> (see [<cite><a class="bibref" rel="biblioentry" href="#bib-WIDGETS-REQS">WIDGETS-REQS</a></cite>]).
      </p>

    </div>
    <div class="appendix section" id="acknowledgements">
      
<!-- OddPage -->
<h2><span class="secno">B. </span>
        Acknowledgements
      </h2>
      <p>
        The editors would like to thank the following contributors (in no particular order): Raine Hillebrand.
      </p>
    </div>

  


<div id="references" class="appendix section">
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<h2><span class="secno">C. </span>References</h2><div id="normative-references" class="section"><h3><span class="secno">C.1 </span>Normative references</h3><dl class="bibliography"><dt id="bib-DOM-LEVEL-3-CORE">[DOM-LEVEL-3-CORE]</dt><dd>Gavin Nicol; et al. <a href="http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407"><cite>Document Object Model (DOM) Level 3 Core Specification.</cite></a> 7 April 2004. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407">http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407</a> 
</dd><dt id="bib-RFC2119">[RFC2119]</dt><dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key words for use in RFCs to Indicate Requirement Levels.</cite></a> March 1997. Internet RFC 2119.  URL: <a href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a> 

</dd><dt id="bib-WIDGETS">[WIDGETS]</dt><dd>Marcos Caceres. <a href="http://www.w3.org/TR/2009/CR-widgets-20091201/"><cite>Widget Packaging and Configuration.</cite></a> 01 December 2009. W3C Candidate Recommendation. (Work in progress.) URL: <a href="http://www.w3.org/TR/2009/CR-widgets-20091201/">http://www.w3.org/TR/2009/CR-widgets-20091201/</a> 
</dd><dt id="bib-WIDGETS-DIGSIG">[WIDGETS-DIGSIG]</dt><dd>Marcos Caceres. <a href="http://www.w3.org/TR/2008/WD-widgets-digsig-20080414"><cite>Widgets 1.0: Digital Signature.</cite></a> 14 April 2008. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2008/WD-widgets-digsig-20080414">http://www.w3.org/TR/2008/WD-widgets-digsig-20080414</a> 
</dd><dt id="bib-XML-NAMES">[XML-NAMES]</dt><dd>Richard Tobin; et al. <a href="http://www.w3.org/TR/2009/REC-xml-names-20091208/"><cite>Namespaces in XML 1.0 (Third Edition).</cite></a> 8 December 2009. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2009/REC-xml-names-20091208/">http://www.w3.org/TR/2009/REC-xml-names-20091208/</a> 

</dd><dt id="bib-XML10">[XML10]</dt><dd>C. M. Sperberg-McQueen; et al. <a href="http://www.w3.org/TR/2008/REC-xml-20081126/"><cite>Extensible Markup Language (XML) 1.0 (Fifth Edition).</cite></a> 26 November 2008. W3C Recommendation. URL: <a href="http://www.w3.org/TR/2008/REC-xml-20081126/">http://www.w3.org/TR/2008/REC-xml-20081126/</a> 
</dd></dl></div><div id="informative-references" class="section"><h3><span class="secno">C.2 </span>Informative references</h3><dl class="bibliography"><dt id="bib-HTTP-TLS">[HTTP-TLS]</dt><dd>E. Rescorla. <a href="http://www.ietf.org/rfc/rfc2818.txt"><cite>HTTP Over TLS.</cite></a> May 2000. Internet RFC 2818. URL: <a href="http://www.ietf.org/rfc/rfc2818.txt">http://www.ietf.org/rfc/rfc2818.txt</a> 
</dd><dt id="bib-HTTP11">[HTTP11]</dt><dd>R. Fielding; et al. <a href="http://www.ietf.org/rfc/rfc2616.txt"><cite>Hypertext Transfer Protocol - HTTP/1.1.</cite></a> June 1999. Internet RFC 2616. URL: <a href="http://www.ietf.org/rfc/rfc2616.txt">http://www.ietf.org/rfc/rfc2616.txt</a> 

</dd><dt id="bib-WIDGETS-REQS">[WIDGETS-REQS]</dt><dd>Marcos Caceres. <a href="http://www.w3.org/TR/2009/WD-widgets-reqs-20090430"><cite>Widgets 1.0: Requirements.</cite></a> 30 April 2009. W3C Working Draft. (Work in progress.) URL: <a href="http://www.w3.org/TR/2009/WD-widgets-reqs-20090430">http://www.w3.org/TR/2009/WD-widgets-reqs-20090430</a> 
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