W3C Mobile Web Initiative

Guidelines for Mobile Web Content Adaptation by Third-Party Proxies

Fran├žois Daoust <fd@w3.org>
W3C Mobile Web Initiative

This set of slides is an HTML version of a talk given at the ICT-MobileSummit 2009 in Santander, Spain. PDF slides at:

Related position paper (PDF format):

ICT-MobileSummit 2009
Santander, Spain

EU FP7 Logo
Supported by MobiWeb2.0, funded by European Union's FP7.


Table of Contents
Photo by Elaine Vallet

  1. About W3C
  2. Motivations
  3. Guidelines Needed!
  4. Legacy is not Future-Proof :(
  5. Outlook / Conclusion

First Part:
About W3C

The World Wide Web Consortium

Leading the Web to its full potential...

W3C is a discussion forum with a clear patent policy for members to agree on and write Web standards The W3C process ensures that resulting standards are stable and interoperable
The W3C Team helps ensure the overall coherence of the standards
Photos by mnadi and psd

Web Standards

Web Standards are building blocks to reach new heights
Photo by Elaine Vallet

Second Part:
Content Transformation - Motivations

Fragmentation is the Mobile plague

Photo by gin able

End users yell: Make it work!

Photo by Elaine Vallet

Possible solution: Content Transformation Proxies

Content Transformation proxies, deployed between origin servers and end-users, enhance the User Agent capabilities and give access to more Web pages

Third Part:
Content Transformation - Guidelines Needed!

Wanted! Legacy

Legacy content and browsers wanted!
Photo by Clemson

Small glitch on Mobile Web pages

Mobile Web pages do not need CT

And yet they were adapted broken in practice

Content Providers yelled: Make it work!

Content Providers yelled against CT deployments
Photo by Elaine Vallet

Control needed

The end user is hardly in control of deployed Content Transformation proxies

Content Transformation Guidelines

Standardization usually helps when stakeholders have diverging needs:

→ The W3C Mobile Web Best Practices working group
        started to work on Content Transformation guidelines
            based on existing technologies.

Global switch to turn off CT

Directive to switch off CT
Photo by El Tekolote

Cache-Control: no-transform

(but the switch unfortunately also prevents optimization)

Do not adapt mobile Web pages

A Web page intended for mobile devices must not be adapted
Photo by Leo Reynolds

What is a mobile Web page?

Content-Type, DOCTYPE, mobileOK claim

Fourth Part:
Legacy is not Future-Proof :(

Copyright infringements?

Is Content Transformation allowed?
Photo by 917press

Web Browsing only

Content Providers yelled against CT deployments
Photo by Elaine Vallet

User-Agent spoofing

Tasting the content is the only way to tell whether the server rejects the response
Photo by mortenjohs

Content tasting. Send the original headers, alter them only if needed.

Same origin policy

DOM accesses, scripts and cookies can only access one origin for security reasons
Photo by Gaetan Lee

→ CT proxies should not play as an origin gateway.


It is impossible to have both Content Transformation and an end-to-end secure channel
Photo by mouton.rebelle
HTTPS communication need to be decrypted by the Content Transformation proxy

Fifth Part:
Outlook / Conclusion

What's next?

What direction should the work follow?
Photo by Un ragazzo chiamato Bi


EU FP7 Logo
Supported by MobiWeb2.0,
funded by European Union's FP7.