Edit comment LC-2052 for Mobile Web Best Practices Working Group

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Comment LC-2052

Comment Shortname:

Commenter: casays <casays@yahoo.com>

Message-id:

Section of the document concerned:

[Free text description]Document as a wholeContent Transformation Guidelines 1.0 Abstract Status of this Document Table of Contents Appendices 1 Introduction (Non-Normative) 1.1 Purpose 1.2 Audience 1.3 Scope 1.4 Summary of Requirements 2 Terminology (Normative) 2.1 Types of Proxy "A transparent proxy is a proxy that does not modify the req... A non-transparent proxy is a proxy that modifies the request... 2.2 Types of Transformation Restructuring content is a process whereby the original layo... Recoding content is a process whereby the layout of the cont... Optimizing content includes removing redundant white space,... 3 Conformance (Normative) 3.1 Classes of Product 3.2 Normative and Informative Parts 3.3 Normative Language for Conformance Requirements 3.4 Content Deployment Conformance 3.5 Transformation Deployment Conformance 4 Behavior of Components (Normative) 4.1 Proxy Forwarding of Request 4.1.1 Applicable HTTP Methods 4.1.2 no-transform directive in Request 4.1.3 Treatment of Requesters that are not Web browsers 4.1.4 Serving Cached Responses 4.1.5 Alteration of HTTP Header Values In this section, the concept of "Web site" is used (rather t... 4.1.5.1 Content Tasting 4.1.5.2 Avoiding "Request Unacceptable" Responses 4.1.5.3 User Selection of Restructured Experience 4.1.5.4 Sequence of Requests 4.1.5.5 Original Headers 4.1.6 Additional HTTP Headers 4.1.6.1 Proxy Treatment of Via Header 4.2 Server Response to Proxy 4.2.1 Use of HTTP 406 Status 4.2.2 Server Origination of Cache-Control: no-transform Including a Cache-Control: no-transform directive can disrup... 4.2.3 Varying Representations 4.2.3.1 Use of Vary HTTP Header 4.2.3.2 Indication of Intended Presentation Media Type of Representation 4.3 Proxy Forwarding of Response to User Agent 4.3.1 Receipt of Cache-Control: no-transform 4.3.2 Receipt of Warning: 214 Transformation Applied 4.3.3 Server Rejection of HTTP Request 4.3.4 Receipt of Vary HTTP Header 4.3.5 Link to "handheld" Representation 4.3.6 Proxy Decision to Transform 4.3.6.1 Alteration of Response 4.3.6.2 HTTPS Link Re-writing 5 Testing (Normative) A References B Example Transformation Interactions (Non-Normative) B.1 Basic Content Tasting by Proxy B.2 Optimization based on Previous Server Interaction B.3 Optimization based on Previous Server Interaction, Server has Changed its Operation B.4 Server Response Indicating that this Representation is Intended for the Target Device B.5 Server Response Indicating that another Representation is Intended for the Target Device C Applicability to Transforming Solutions which are Out of Scope (Non-Normative) D Scope for Future Work (Non-Normative) D.1 POWDER D.2 link HTTP Header D.3 Sources of Device Information D.4 Inter Proxy Communication D.5 Amendment to and Refinement of HTTP E Administrative Arrangements (Non-Normative) F Acknowledgments (Non-Normative)
or

Refinement of the section concerned:

Status:

open proposal pending resolved_yes resolved_no resolved_partial other assigned to Nobody

Type: substantive editorial typo question general comment undefined

Resolution status:

Response drafted Resolution implemented Reply sent to commenter

Response status:

No response from Commenter yet Commenter approved disposition Commenter objected to disposition
Commenter's response (URI):

Comment:

3) Section 4.3.6

The third bullet under "examples of heuristics" is to be split
into two points:

"the Content-Type of the response are known to be specific to the
device or class of device. At a minimum, the following MIME types
intended for mobile Web browsers MUST represent mobile-optimized
content:

Browsing XHTML-related
application/vnd.wap.xhtml+xml
application/xhtml+xml
Browsing WML-related
text/vnd.wap.wml
application/vnd.wap.wmlc
text/vnd.wap.wml+xml
text/vnd.wap.wmlscript
application/vnd.wap.wmlscriptc
image/vnd.wap.wbmp
application/vnd.wap.wbxml
Browsing and downloading
application/vnd.wap.multipart.mixed
application/vnd.wap.multipart.related
application/vnd.wap.multipart.alternative
application/vnd.wap.multipart.form-data

In addition, the following MIME types of the form */x-up-*
SHOULD be considered as representing mobile-optimized
content, at a minimum:

Legacy Openwave
image/x-up-wpng
image/x-up-bmp

The range of MIME types is intended to cover typical mobile
browsing applications.

Transformations specified by the relevant standards are allowed
(WAP-236 WAE specifications 19.12.2001, WAP-192 WBXML specifications
25.7.2001, WAP-191 WML specifications 19.2.2000 and predecessors,
WAP-193 WMLScript specifications 25.10.2000).

In accordance with Internet standards and practices, a proxy
SHOULD determine whether a content is mobile-optimized FIRST by
examining the HTTP header field content-type, before inspecting
the XML declaration and its associated DOCTYPE."

Rationale: Inspection of the HTTP field Content-type is an
usual mode of operation amongst transcoders. It is also simpler
and safer than applying heuristics on DOCTYPE, because inspecting
the content of a body requires one to deal with character encoding
issues (see RFC3023, XML 1.1 sections 4.3.3 and E), or parsing
multipart-structured content; these are unnecessary when handling
HTTP fields. Finally, specifying a minimum set of required MIME
types to take into account helps ensure that proxies will exhibit a
standard behaviour, and that non-textual content types for which
there is no DOCTYPE (notably mobile-specific image formats) are
properly dealt with. A normative document cannot leave full freedom
to implementors to select whichever subset of content types are to
be considered mobile-optimized or not.

4) Section 4.3.6

The second part of the bullet split as described in (b) is to contain
the following:

"other aspects of the response such as the DOCTYPE are known to be
specific to the device or class of device.

At a minimum, the following DOCTYPEs MUST be considered as
mobile-specific:

XHTML mobile profile
-//OMA//DTD XHTML Mobile 1.2//EN
-//WAPFORUM//DTD XHTML Mobile 1.1//EN
-//WAPFORUM//DTD XHTML Mobile 1.0//EN
XHTML basic
-//W3C//DTD XHTML Basic 1.1//EN
-//W3C//DTD XHTML Basic 1.0//EN
-//OPENWAVE//DTD XHTML 1.0//EN
-//OPENWAVE//DTD XHTML Mobile 1.0//EN
XHTML i-Mode
-//i-mode group (ja)//DTD XHTML i-XHTML (Locale/Ver.=ja/1.0) 1.0//EN
-//i-mode group (ja)//DTD XHTML i-XHTML (Locale/Ver.=ja/1.1) 1.0//EN
-//i-mode group (ja)//DTD XHTML i-XHTML (Locale/Ver.=ja/2.0) 1.0//EN
-//i-mode group (ja)//DTD XHTML i-XHTML (Locale/Ver.=ja/2.1) 1.0//EN
-//i-mode group (ja)//DTD XHTML i-XHTML (Locale/Ver.=ja/2.2) 1.0//EN
[list completed in http://lists.w3.org/Archives/Public/public-bpwg-comments/2008JulSep/0150.html with:
-//i-mode group (ja)//DTD XHTML i-XHTML (Locale/Ver.=ja/2.3)
1.0//EN]
Compact HTML
-//W3C//DTD Compact HTML 1.0 Draft//EN
-//BBSW//DTD Compact HTML 2.0//EN

The following DOCTYPEs MUST be considered as mobile-specific.
Transformations explicitly provided for by the relevant standards
are allowed (WAP-192 WBXML specifications 25.7.2001, WAP-236 WAE
specifications 19.12.2001, WAP-191 WML specifications 19.2.2000
and predecessors, WAP-193 WMLScript specifications 25.10.2000).

WML
-//WAPFORUM//DTD WML 1.0//EN
-//WAPFORUM//DTD WML 1.1//EN
-//WAPFORUM//DTD WML 1.2//EN
-//WAPFORUM//DTD WML 1.3//EN
-//WAPFORUM//DTD WML 2.0//EN
-//PHONE.COM//DTD WML 1.1//EN
-//OPENWAVE.COM//DTD WML 1.3//EN

The range of MIME types is intended to cover typical mobile
browsing applications."

Rationale: A normative document cannot leave full freedom to
implementors to select whichever subset of DOCTYPEs are
considered mobile-optimized or not. This helps ensure that
transformation proxies exhibit a standard behaviour.

Related issues: (space separated ids)

WG Notes: See: http://www.w3.org/2008/10/20-bpwg-minutes.html#item23 and: http://www.w3.org/2008/10/20-bpwg-minutes.html#item27 Final resolutions: - Remove examples of heuristics from the main run of text and include Appendices to list in a *non-endorsed* way lists of stuff that other people have used but are No-endorsed by us, and did I mentionthat they are not endorsed - Ref LC-2048 and LC-2002, LC-2052 and LC-2021, resolve partial, and say that we include these examples as non-endorsed heuristics in the non endorsed heuristics appendix

Resolution: The list of Internet content types associated with mobile content is to be found in Appendix C, referenced by the third bullet in 4.2.9 Proxy Decision to Transform. It contains all the requested content types, except "application/xhtml+xml" as this content type cannot be unambiguously associated with mobile content. The appendix is available at: http://www.w3.org/TR/2009/WD-ct-guidelines-20091006/Overview.html#sec-Mobile-Content-Types

(Please make sure the resolution is adapted for public consumption)