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472 lines
28 KiB
472 lines
28 KiB
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</head>
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<body>
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<div class="head">
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<p><a href="http://www.w3.org/"><img alt="W3C" height="48"
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src="http://www.w3.org/Icons/w3c_home" width="72" /></a></p>
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<h1><a id="title" name="title" />Content Transformation Landscape 1.0</h1>
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<h2><a id="w3c-doctype" name="w3c-doctype" />W3C Working Group Note 27 October 2009</h2>
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<dl>
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<dt>This version:</dt>
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<dd>
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<a href="http://www.w3.org/TR/2009/NOTE-ct-landscape-20091027/">http://www.w3.org/TR/2009/NOTE-ct-landscape-20091027/</a>
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</dd>
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<dt>Latest version:</dt>
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<dd>
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<a href="http://www.w3.org/TR/ct-landscape/">http://www.w3.org/TR/ct-landscape/</a>
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</dd>
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<dt>Previous version:</dt>
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<dd>
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<a href="http://www.w3.org/TR/2007/WD-ct-landscape-20071025/">http://www.w3.org/TR/2007/WD-ct-landscape-20071025/</a>
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</dd>
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<dt>Editors:</dt>
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<dd>Jo Rabin, dotMobi</dd>
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<dd>Andrew Swainston [Initial Draft], Vodafone UK</dd>
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</dl>
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<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
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>Copyright</a> © 2009 <a href="http://www.w3.org/"><acronym
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title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a
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href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology"
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>MIT</acronym></a>, <a href="http://www.ercim.org/"><acronym
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title="European Research Consortium for Informatics and Mathematics"
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>ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
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<a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a
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href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a
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href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules
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apply.</p>
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</div>
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<hr />
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<div><h2><a id="abstract" name="abstract" />Abstract</h2><p>This document identifies the issues
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surrounding use of transforming proxies in the delivery of Web content. It does not comment
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on the techniques that cause these issues, it merely identifies them in order to inform the
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requirements of the Content Transformation Guidelines document. That document is to offer
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recommendations as to how components of the delivery context can cooperate to achieve, at a
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minimum, a functional user experience.</p><p>In this revision the document is largely
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historical - the Content Transformation Guidelines document, published under the title
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<a href="http://www.w3.org/TR/ct-guidelines/">"Guidelines for Web Content Transformation Proxies"</a> was initially inspired by the set
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of requirements identified in this document, but has subsequently evolved based on
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available technologies and feedback.</p></div>
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<div>
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<h2><a id="status" name="status" />Status of this Document</h2>
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<p>
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<em>This section describes the status of this document at the time of its publication. Other
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documents may supersede this document. A list of current W3C publications and the latest
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revision of this technical report can be found in the <a href="http://www.w3.org/TR/">W3C
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technical reports index</a> at http://www.w3.org/TR/.</em></p>
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<p>This document was produced by the <a
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href="http://www.w3.org/2005/MWI/BPWG/Group/TaskForces/CT/">Content Transformation Task
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Force</a> of the <a href="http://www.w3.org/2005/MWI/BPWG/">Mobile Web Best Practices
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Working Group</a> as part of the <a href="http://www.w3.org/2005/MWI/Activity">Mobile Web
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Initiative</a>. It is the <em>Problem Statement</em> referred to in the <a
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href="http://www.w3.org/2005/MWI/BPWG/Group/TaskForces/CT/#charter">Charter</a> of the W3C
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Mobile Web Initiative Best Practices Working Group <a
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href="http://www.w3.org/2005/MWI/BPWG/Group/TaskForces/CT/">Content Transformation Task
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Force</a>, and served as a basis for the work on the <a
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href="http://www.w3.org/TR/ct-guidelines/">Guidelines for Web Content Transformation Proxies</a>.</p>
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<p>Publication as a Working Group Note 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>
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<p>Changes since publication of the previous <a href="http://www.w3.org/TR/2007/WD-ct-landscape-20071025/">Working Draft</a> (published on 25 October 2007) are an update of the <a href="#abstract">Abstract</a> section to clarify the historical status of this work and refer to the normative <a href="http://www.w3.org/TR/ct-guidelines/">Guidelines for Web Content Transformation Proxies</a> document that was initially inspired by this document. The Working Group does not anticipate any further change on this document.</p>
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<p>Comments on this document may be sent to the Working Group's public email list <a href="mailto:public-bpwg-comments@w3.org">public-bpwg-comments@w3.org</a>, a <a href="http://lists.w3.org/Archives/Public/public-bpwg-comments/">publicly archived mailing list</a>. The Working Group rather expects comments to be made against the normative <a href="http://www.w3.org/TR/ct-guidelines/">Guidelines for Web Content Transformation Proxies</a> document.</p>
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<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 rel="disclosure" href="http://www.w3.org/2004/01/pp-impl/37584/status">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>
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</div>
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<div class="toc">
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<h2><a id="contents" name="contents" />Table of Contents</h2>
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<p class="toc">1 <a href="#introduction">Introduction</a><br /> 1.1 <a href="#d0e113"
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>Purpose</a><br /> 1.2 <a href="#d0e121">Scope</a><br /> 1.3 <a
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href="#d0e128">Structure of the Document</a><br /> 2 <a href="#landscape">Landscape</a><br
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/> 2.1 <a href="#d0e144">Accessing Web Content from Mobile Devices</a><br />
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2.2 <a href="#d0e182">Content Transformation Proxies</a><br /> 2.2.1
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<a href="#d0e211">Advantages of Content Transformation</a><br /> 2.2.2 <a
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href="#d0e224">Issues with Content Transformation</a><br />
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2.2.2.1 <a href="#d0e227">Web Presentation</a><br />
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2.2.2.2 <a href="#d0e248">Non Web Applications</a><br />
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2.2.2.3 <a href="#d0e276">Legal, Moral and Commercial Issues</a><br
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/> 2.2.2.4 <a href="#d0e292">Security Issues</a><br /> 3 <a
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href="#constraints">Constraints</a><br /></p>
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<h3><a id="appendices" name="appendices" />Appendices</h3>
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<p class="toc">A <a href="#terminologyNote">Terminology</a> (Non-Normative)<br /> B <a
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href="#d0e364">References</a> (Non-Normative)<br /> C <a href="#d0e374"
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>Acknowledgments</a> (Non-Normative)<br /></p>
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</div>
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<hr />
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<div class="body">
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<div class="div1">
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<h2><a id="introduction" name="introduction" />1 Introduction</h2>
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<p>Mobile Web Best Practices <a href="#BestPractices">[BestPractices]</a> encourages content
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providers to produce "made for mobile" experiences of their Web sites. While the number of
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such Web sites continues to increase, there are still many Web sites that are unaware of
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mobile presentation. Those Web sites, when accessed from mobile devices, do not present a
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satisfactory user experience or may indeed cause failure of the user's device. In order to
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mitigate this unsatisfactory experience, mobile network operators and others use proxies
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to transform the content of these sites.</p>
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<p>At the same time there are an increasing number of highly capable mobile devices that
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offer enhanced browsing experiences designed to assist users of mobile devices with their
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typically small screen and limited input capabilities to navigate sites designed with
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larger displays, pointing devices and full keyboards in mind.</p>
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<p>The W3C MWI <a href="http://www.w3.org/2005/MWI/BPWG/">Best Practices Working Group</a>
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recognizes that on the one hand transforming proxies can diminish the value of sites that
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have been designed specifically for mobile presentation. On the other hand transforming
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proxies can enhance the mobile experience of sites unaware of mobile presentation. Yet
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again, transforming proxies can diminish the value of such sites when presented on devices
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that are capable of simulating a desktop experience while mobile.</p>
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<div class="div2">
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<h3><a id="d0e113" name="d0e113" />1.1 Purpose</h3>
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<p>This document identifies specific issues that can result from content transformation
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and identifies requirements that must be fulfilled by the Content Transformation
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Guidelines document. That document identifies techniques that are designed to help
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components in the Delivery Context cooperate in the presentation of Web sites in order
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that users experience, at a minimum, a <a
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href="http://www.w3.org/TR/2005/WD-di-gloss-20050118/#def-functional-user-experience"
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>functional user experience</a> and that authors' intentions are fulfilled to whatever
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degree possible.</p>
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</div>
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<div class="div2">
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<h3><a id="d0e121" name="d0e121" />1.2 Scope</h3>
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<p>While the Working Group's charter refers specifically to mobile, the Working Group
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recognizes that the issues here relate to any non-desktop presentation of content, or
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indeed presentation of any content that has alternative representations. Hence, in the
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following, requirements are presented in a more general form.</p>
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<p>This document does not offer comment on the rights and wrongs of any particular issues
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it mentions. It does not condone nor deprecate any particular technique. They are
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mentioned in order to clarify the requirements of the Guidelines document that
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consequently addresses the issues mentioned.</p>
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</div>
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<div class="div2">
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<h3><a id="d0e128" name="d0e128" />1.3 Structure of the Document</h3>
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<p>In <a href="#landscape"><b>2 Landscape</b></a> the document identifies specific
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benefits and issues relating to content transformation. Where requirements can be
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inferred from the discussion they are identified in the text, thus:</p>
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<p class="requirement">This is a requirement.</p>
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<p>Various technologies and techniques that must be taken into account when satisfying the
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requirements are identified in <a href="#constraints"><b>3 Constraints</b></a>.</p>
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</div>
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</div>
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<div class="div1">
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<h2><a id="landscape" name="landscape" />2 Landscape</h2>
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<div class="div2">
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<h3><a id="d0e144" name="d0e144" />2.1 Accessing Web Content from Mobile Devices</h3>
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<p>While an increasing number of Web sites [<a id="mobileAware" name="mobileAware"
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title="Mobile Aware">Definition</a>: mobile aware] are being designed specifically to
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tailor their presentation to be suitable for users in a mobile context (see <a
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href="#BestPractices">[BestPractices]</a>), many Web sites [<a id="mobileUnaware"
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name="mobileUnaware" title="Mobile Unaware">Definition</a>: mobile unaware] have been
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(and continue to be) designed with only the features of desktop browsers in mind. From a
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mobile perspective, typical issues with the resulting Web pages are:</p>
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<ul>
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<li>
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<p>page layouts assume a screen larger than the device supports;</p>
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</li>
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<li>
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<p>pages require more memory than the device supports;</p>
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</li>
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<li>
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<p>the design of interaction with the page assumes that a full qwerty keyboard and
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mouse are available;</p>
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</li>
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<li>
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<p>pages use content types that the device does not support.</p>
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</li>
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</ul>
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<p>As a result accessing such a Web page from a mobile device often results in a poor or
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unusable experience (The differences between desktop and mobile presentation are
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discussed in more detail in <a href="#BestPractices">[BestPractices]</a> - <a
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href="http://www.w3.org/TR/mobile-bp/#requirements">2 Requirements</a>).</p>
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<p>Some Web sites [<a id="mobileBlocking" name="mobileBlocking" title="mobile blocking"
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>Definition</a>: mobile blocking], aware that access is not from the expected desktop
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context, send either an HTTP error status code or an HTTP success code accompanied by
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text indicating that they cannot present an acceptable experience for the user - thus
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preventing access from mobile users.</p>
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</div>
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<div class="div2">
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<h3><a id="d0e182" name="d0e182" />2.2 Content Transformation Proxies</h3>
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<p>Mobile operators, search engines and others recognize that while the number of mobile
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friendly Web sites is growing, there will remain a considerable number of mobile unaware
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and mobile blocking sites. One approach to providing a more satisfactory mobile user
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experience of mobile unaware and blocking sites is to insert an intermediary in the
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communications path between the user agent and the origin server. These intermediaries,
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known as [<a id="ctf" name="ctf" title="content transformation proxy">Definition</a>:
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content transformation proxies] (see <a href="#terminologyNote"><b>A
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Terminology</b></a>) adjust HTML pages designed for desktop presentation to provide an
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enhanced user experience when accessed from a mobile device.</p>
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<p>In order to avoid blocking behavior and in order to achieve a consistent presentation
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from Web sites that vary their experience according to the browser type, proxies
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typically work by masquerading as a specific desktop browser, fetching content and then
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modifying it before returning it to mobile devices. These transformations include:</p>
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<ul>
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<li>
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<p>character encoding corrections,</p>
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</li>
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<li>
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<p>image reformatting and resizing, </p>
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</li>
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<li>
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<p>layout modifications and page segmentation, </p>
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</li>
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<li>
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<p>multi step JavaScript transaction emulation.</p>
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</li>
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</ul>
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<p>Content transformation proxies can also add content to, or remove it from a page.</p>
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<p class="requirement" id="req1">1. It must be possible to make a distinction between
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different types of transformation - e.g. correction of malformed markup as opposed to
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pagination and addition of headers and footers.</p>
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<div class="div3">
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<h4><a id="d0e211" name="d0e211" />2.2.1 Advantages of Content Transformation</h4>
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<p>The principal advantage of Content Transformation is that it provides the ability for
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mobile users to enjoy a Web experience even though a large number of Web sites that
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are mobile unaware or mobile blocking.</p>
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<p class="requirement" id="req2">2. Transforming proxies must be able to overcome the
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behavior of "blocking" sites.</p>
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<p>Content transformation also offers opportunities to site designers, allowing their
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sites to be served to a wide range or devices while freeing them from having to detect
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and keep up to date with the capabilities of new devices.</p>
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<p class="requirement" id="req3">3. Transforming proxies must be able to identify their
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presence and advertise their capabilities.</p>
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<p class="requirement" id="req4">4. Origin servers must be able to selectively enable or
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disable features of transforming proxies.</p>
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</div>
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<div class="div3">
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<h4><a id="d0e224" name="d0e224" />2.2.2 Issues with Content Transformation</h4>
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<div class="div4">
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<h5><a id="d0e227" name="d0e227" />2.2.2.1 Web Presentation</h5>
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<p>By presenting requests as though they came from a different device, Content
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Transformation prevents mobile aware sites from detecting the actual mobile devices
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behind the request. As a result, mobile aware sites whose purpose is to provide
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mobile compatible pages or mobile compatible content like ring-tones or Java
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applications are unable to operate correctly. Such sites require information about
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the actual device.</p>
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<p class="requirement" id="req5">5. Origin servers and proxies must be able to
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identify the actual identity of components of the delivery context, including
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(other) proxies and browsers.</p>
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<p>When mobile aware sites send content to devices, they often choose to deliver very
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specific variations on their content tailored exactly for the device. Any attempt by
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a content transformation proxy to change the content may very well destroy or in any
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case decrease the value of the content. For example, a site which delivers ring
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tones or wallpaper which it tailors exactly to devices' characteristics may be
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rendered useless if the audio format is changed, or less valuable if the color depth
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of an image is reduced to something below that which the device is capable of
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rendering.</p>
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<p class="requirement" id="req6">6. Origin servers must be able to prohibit any kind
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of transformation of its content.</p>
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<p class="requirement" id="req9">7. Origin servers must be able to advertise author
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preferences.</p>
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<p>Some Web sites cater for both desktop browsers and mobile devices, especially when
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the site recognizes that the device has a browser that is capable of providing a
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'full screen' presentation mode. In these cases the user of the mobile device may be
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prevented from exercising their choice of presentation and may be unable to access
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either the site's mobile or desktop presentation in its original form.</p>
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<p class="requirement" id="req7">8. Browsers must be able to identify and advertise
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user interface modalities.</p>
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<p class="requirement" id="req8">9. Components must be able to solicit and advertise
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user choice.</p>
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<p class="requirement" id="req10">10. Origin servers must be able to identify and
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advertise different representations they may have available.</p>
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</div>
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<div class="div4">
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<h5><a id="d0e248" name="d0e248" />2.2.2.2 Non Web Applications</h5>
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<p>In the mobile Internet, just like the Internet as a whole, communication between a
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client and a server is not confined to Web applications. In the mobile world,
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however, use of HTTP as a bearer for other applications is, if anything, even more
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prevalent. Services are often designed this way as a result of there being no access
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to TCP sockets on clients, or fears of non-transparency of gateways. Examples
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include:</p>
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<ul>
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<li>
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<p>J2ME client applications</p>
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</li>
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<li>
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<p>native applications (Symbian for Symbian devices, Microsoft for Microsoft
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devices, etc.)</p>
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</li>
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<li>
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<p>Adobe Flash applications</p>
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</li>
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<li>
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<p>SVGT documents</p>
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</li>
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<li>
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<p>Ajax applications embedded in HTML</p>
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</li>
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</ul>
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|
<p>There are many other examples, but these are sufficient to illustrate a point: not
|
|
all clients using HTTP as a communication protocol with an origin server are
|
|
interested in "content transformation". In fact, transformation may break the
|
|
semantics of the client-server communication and render the application completely
|
|
useless.</p>
|
|
<p class="requirement">See <a href="#req6">Requirement 6</a> above.</p>
|
|
</div>
|
|
<div class="div4">
|
|
<h5><a id="d0e276" name="d0e276" />2.2.2.3 Legal, Moral and Commercial Issues</h5>
|
|
<p>A further issue concerns the limits of acceptable content transformation and to
|
|
what degree content providers can reasonably expect to remain in control of how
|
|
their content is presented.</p>
|
|
<p>Some content providers may feel that, for whatever reason, their content should not
|
|
be fragmented, or their images removed or transformed. In a medical application, for
|
|
example, it may be essential that an image is presented in its original format.</p>
|
|
<p class="requirement">See <a href="#req6">Requirement 6</a> above.</p>
|
|
<p>An example of the commercial issues is removing advertising banners from the origin
|
|
server and perhaps even replacing them with new advertisements adapted for the
|
|
specific user agent. This is obviously controversial because it hi-jacks an
|
|
advertising revenue stream from the origin server.</p>
|
|
<p class="requirement" id="req11">11. It must be possible for origin servers
|
|
selectively to indicate that content of various types must not be removed, replaced
|
|
or inserted by transforming proxies.</p>
|
|
</div>
|
|
<div class="div4">
|
|
<h5><a id="d0e292" name="d0e292" />2.2.2.4 Security Issues</h5>
|
|
<p>The most commonly used security mechanisms require a direct connection between the
|
|
origin server and the ultimate client. Intermediaries of any kind, including content
|
|
transformation proxies, may break this security model and cause exposure to theft of
|
|
sensitive information.</p>
|
|
<p class="requirement" id="req12">12. It must be possible to establish a secure end to
|
|
end connection.</p>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div class="div1">
|
|
<h2><a id="constraints" name="constraints" />3 Constraints</h2>
|
|
<p>The BPWG, and hence the Content Transformation Task Force, is not chartered to create
|
|
"new technology", rather it is chartered to advise on the use of existing technology.
|
|
Hence the techniques should operate within existing technology. That said, the Task Force
|
|
is free to suggest new mechanisms and enhancements to existing mechanisms to other W3C
|
|
groups that are chartered with the development of such technology.</p>
|
|
<p>Examples of technologies and techniques that will be further investigated include, but
|
|
are not limited to:</p>
|
|
<ul>
|
|
<li>
|
|
<p>The HTTP protocol <a href="#HTTP">[HTTP]</a>, which provides several mechanisms that
|
|
are likely to be useful. In particular to promote awareness of the "<a
|
|
href="http://tools.ietf.org/html/rfc2616#section-14.9.5">Cache-Control:
|
|
no-transform</a>" HTTP directive, or other mechanism for allowing content authors to
|
|
prohibit transformation of a resource by intermediaries.</p>
|
|
</li>
|
|
<li>
|
|
<p>The <a href="http://www.w3.org/2007/powder/">POWDER</a> protocol, which provide
|
|
mechanisms for describing resources using RDF and OWL. More generally, ascertaining
|
|
that a representation of a resource is suitable for the user's delivery context either
|
|
because the resource has been so described or from the nature of the representation of
|
|
the resource.</p>
|
|
</li>
|
|
<li>
|
|
<p>mobileOK (see <a href="#mobileOKBasic10Tests">[mobileOKBasic10Tests]</a>) which is a
|
|
claim that can be represented using (POWDER) Web Description Resources, that a
|
|
resource achieves certain minimum interoperability requirements for mobile
|
|
delivery.</p>
|
|
</li>
|
|
<li>
|
|
<p>The work of the <a href="http://www.w3.org/2005/MWI/DDWG/">W3C MWI DDWG</a> relating
|
|
to definition of device capabilities.</p>
|
|
</li>
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
<div class="back">
|
|
<div class="div1">
|
|
<h2><a id="terminologyNote" name="terminologyNote" />A Terminology (Non-Normative)</h2>
|
|
<p>In <a href="#HTTP">[HTTP]</a>, <a href="http://tools.ietf.org/html/rfc2616#section-1.3"
|
|
>1.3 Terminology</a> various types of intermediary are described:</p>
|
|
<dl>
|
|
<dt class="label">Proxy</dt>
|
|
<dd>
|
|
<p>A proxy is a forwarding agent, receiving requests for a URI in its absolute form,
|
|
rewriting all or part of the message, and forwarding the reformatted request toward
|
|
the server identified by the URI.</p>
|
|
</dd>
|
|
<dt class="label">Gateway</dt>
|
|
<dd>
|
|
<p>A gateway is a receiving agent, acting as a layer above some other server(s) and, if
|
|
necessary, translating the requests to the underlying server's protocol.</p>
|
|
</dd>
|
|
<dt class="label">Tunnel</dt>
|
|
<dd>
|
|
<p>A tunnel acts as a relay point between two connections without changing the messages;
|
|
tunnels are used when the communication needs to pass through an intermediary (such as
|
|
a firewall) even when the intermediary cannot understand the contents of the
|
|
messages.</p>
|
|
</dd>
|
|
</dl>
|
|
<p>The term "content transformation proxy" has become popular for a special type of gateway:
|
|
one that transforms content as described above. The term "content transformation gateway"
|
|
would perhaps have been a better choice or maybe even "content transformation proxy
|
|
gateway", since the relevant server technology actually is both a proxy and a gateway.</p>
|
|
</div>
|
|
<div class="div1">
|
|
<h2><a id="d0e364" name="d0e364" />B References (Non-Normative)</h2>
|
|
<dl>
|
|
<dt class="label"><a id="BestPractices" name="BestPractices" />BestPractices</dt>
|
|
<dd>Mobile Web Best Practices 1.0 Basic Guidelines, Jo Rabin, Charles McCathieNevile (eds), W3C Recommendation, 29 July 2008 (See <a href="http://www.w3.org/TR/2008/REC-mobile-bp-20080729/">http://www.w3.org/TR/2008/REC-mobile-bp-20080729/</a>)</dd>
|
|
<dt class="label"><a id="mobileOKBasic10Tests" name="mobileOKBasic10Tests"
|
|
/>mobileOKBasic10Tests</dt>
|
|
<dd>W3C mobileOK Basic Tests 1.0, Sean Owen, Jo Rabin (eds), W3C Recommendation, 08 December 2008 (See <a href="http://www.w3.org/TR/2008/REC-mobileOK-basic10-tests-20081208/">http://www.w3.org/TR/2008/REC-mobileOK-basic10-tests-20081208/</a>)</dd>
|
|
<dt class="label"><a id="HTTP" name="HTTP" />HTTP</dt>
|
|
<dd> Hypertext Transfer Protocol -- HTTP/1.1 Request for Comments: 2616, R. Fielding, J.
|
|
Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee, June 1999 (See
|
|
http://tools.ietf.org/html/rfc2616.)</dd>
|
|
</dl>
|
|
</div>
|
|
<div class="div1">
|
|
<h2><a id="d0e374" name="d0e374" />C Acknowledgments (Non-Normative)</h2>
|
|
<p>The editors acknowledge contributions of various kinds from members of the MWI BPWG <a
|
|
href="http://www.w3.org/2005/MWI/BPWG/Group/TaskForces/CT/">Content Transformation Task
|
|
Force</a>.</p>
|
|
<p>The editors acknowledge significant written contributions from:</p>
|
|
<ul>
|
|
<li>Magnus Lonnroth, Drutt</li>
|
|
</ul>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|