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Content Adaptation & the Adoption of Industry Standards
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This document outlines the interaction between OpenWeb, standards bodies and developer initiatives to support the mobile ecosystem.
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OpenWeb is a content adaptation platform that transparently intercepts requests for standard web sites and converts the web pages into highly compressed, functional mobile phone-compliant WAP2 pages. The platform is deployed into an operator network and seeks to bring to mobile browsers content from the large number of web sites that are not currently designed for mobile usage.
We define the Mobile Ecosystem as being all the participants active in making mobile browsing successful. This includes network operators, equipment vendors, content developers and consumers. By working together we aim to reduce barriers to mobile web usage and to encourage user take up, by allowing the continuing development of new services and concepts.
Openwave is proud to take an active role in the developments of standard both for the web in general, the mobile ecosystem and for content adaptation in particular. We work actively to ensure best practice and to ensure OpenWeb is a positive member of the community.
Standards work includes the following:
Openwave is a full member of the W3C Standard Group and active participants in the Mobile Web Best Practice Group. The group is currently working on Content Adaptation guidelines, which are due for release for public review during 2008.
We also support the work of the W3C Web Accessibility Initiative.
> BPWG Group Home Page
> Content Transformation Task Force Home Page
The OpenWeb Product Group is also proud to be the first vendor signatory to the Developer Manifesto for Responsible Reformatting. The purpose of this document is to lay down guidelines for content adaptation vendors, to ensure we handle correctly web sites that have already been designed for mobile browsing. Please see http://wurfl.sourceforge.net/manifesto/ for more information.
OpenWeb is already compliant today with many of the guidelines laid out below. We aim to make OpenWeb fully compliant by version 5.7.4, due for release in September 2008.
How to Avoid Reformatting Mobile-Optimised Sites
As a general rule, transcoders should err on the side of non-reformatting, meaning that a reformatting proxy should refrain from reformatting in all of those cases when a site might already be suitable for mobile.
In particular, developers request that the following rules are observed:
- No USER AGENT Spoofing: under no circumstances should the original User-Agent string be removed, modified or moved to a different header.
Note: It is considered acceptable for a transcoder to perform a second HTTP fetch of site content with a spoofed HTTP request, as long as the first request has been performed with the original headers and the proxy has positively identified that the website is NOT mobile optmised
- Preserve headers: under no circumstances should a transcoder modify or delete existing HTTP headers. The addition of extra x-* headers is admissible.
- Recognize Mobile-Specific MIME-types and Document Type Declarations (DTDs): documents served with the following MIME types:
application/xhtml+xml,
text/vnd.wap.wml,
application/vnd.wap.xhtml+xml
and documents served with the XHTML-Basic 1.0 or XHTML-MP 1.1 DTD:
<!DOCTYPE html PUBLIC "-//OMA//DTD XHTML Mobile 1.2//EN"
"http://www.openmobilealliance.org/tech/DTD/xhtml-mobile12.dtd">
<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.1//EN"
"http://www.wapforum.org/DTD/xhtml-mobile11.dtd">
<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.0//EN"
"http://www.wapforum.org/DTD/xhtml-mobile10.dtd">
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd">
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
MUST be considered mobile-optimised and no transcoding should be applied
- Do Not Adapt pictures of mobile-optimized sites: mobile-optimized sites should not have their graphics adapted.
- 30Kb Limit: pages that have a total weight of 30 kilobytes or less MUST not be adapted.
Note: An exception can be made in those cases when none of the other rules apply AND the reformatting proxy is able to positively identify devices which cannot handle 30kb of content through a Device Description Repository (DDR).
In this case a lower threshold for reformatting may be adopted. The limit cannot be lower than 15 kilobytes under any circumstances.
A further exception can be made in those cases when the reformatting proxy can positively identify the web-only nature of the site by using more sophisticated techniques, such as: detecting the use of IFRAMES and other "web-only" tags and scripting. The limit cannot be lower than 15 kilobytes under any circumstances.
- Do not reformat pages that return the following HTTP header:
Cache-Control: no-transform
This also applies to the case when the header is specified through the <meta> HTTP-Equiv tag
- Do not reformat pages which contain the following meta tag:
<link rel="alternate" type="text/html" media="handheld" href="[url]" title="[title]" />
The proxy should redirect the user to the [url] contained in the href attribute.
- Transcoders MUST not reformat sites with URLs matching one of the following patterns:
m.*
mobile.*
wap.*
*.mobi
pda.*
avantgo.*
iphone.*
wml.*
wireless.*
xhtml.*
Note: In the spirit of erring on the side of non-reformatting, vendors are also welcome to support the following exclusion patterns, where "/" represents the first slash in the url PATH:
*/mobile/
*/iphone/
*/wireless/
Support for these extra exclusion patterns is only recommended
- Whitelists are acceptable only as inclusion list to inform the reformatter of sites which would normally escape reformatting, but which are marked as reformattable through human intervention. Use of exclusion whitelists is not acceptable.
- Transcoders must identify themselves using the Via header as enforced by the HTTP protocol, RFC 2616
( See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.45 )
- Transcoders must send along the IP address of the device/gateway and other proxies using the X-Forwarded-For header, a de-facto standard, http://en.wikipedia.org/wiki/X-Forwarded-For
Reformatter vendors who abide by the rules above for their products' standard configuration and who agree to notify their customers of the importance of behaving sympathetically in the ecosystem are invited to sign the Manifesto.
Operators who need to deploy content reformatting solutions on their network are welcome to read this document and to derive the requirements for their systems from it.
Mobile developers are welcome to sign the Manifesto by sending an email to the editor and requesting that their signature is added.
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