Luca Passani, the co-creator and maintainer of the WURFL mobile device characteristics database, with input from other mobile developers has published what he calls a “Manifesto for Ethical Reformatting“. The manifesto outlines some simple rules for how transcoding can work to make non-mobile websites usable on any phone, without breaking the mobile web. This manifesto is a reation to the current transcoding implementations from Vodafone in the UK, Spain, and Portugal with Novarra, and Vodafone Ireland with Bytemobile and Sprint USA using Openwave – all of which are hurting usability by reformatting mobile sites that don’t need it and by removing and changing html headers with negative consequences for content delivery services.
The rules are:
- No USER AGENT Spoofing: under no circumstances should the original User-Agent string be removed, modified or moved to a different header.
- 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:
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-optimized 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.
- do not reformat pages that return the HTTP header:
Cache-Control: no-transformThis 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
- Transcoders MUST not reformat sites with URLs matching one of the following patterns:
- 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.
These seem like reasonable guidelines that both transcoding proxy vendors and mobile developers can live with. I hope that Novarra, Openwave (which has been reaching out to the development community and promises significant improvements in the next release) and Bytemobile will adopt thes guidelines. It’s in everyone’s best interest; web developers, vendors of content reformatting transcoders and users. For developers of mobile content and users it insures that the mobile web and mobile content services work as designed and for transcoder vendors it lets them concentrate on the worthwhile goal of mobilizing the full-web without the negative publicity that breaking mobile services creates.