The job of the CDS is quite simple. It runs on a single well-known domain, and providers a pointer to a user's PDS. The only user interface required is to get the user's consent to set/modify their PDS on a particular browser.
The following is a summary of the requirements for the CDS:
- A single global domain is setup, such as cds.com
- If a user is redirected to cds.com/setpds?dm=<domainname>&continue=<URL destination at domainname> then the cds.com webserver will ask the user "Please confirm you would like all the websites you visit to be able to determine that <Domainname> has your web browsing preferences."
- If the user says yes, a cookie on cds.com is set with the value of that domainname, and the time at which it was set.
- If the user already had a PDS set, the question above would be appended with "(Your previously had listed <olddomainname> as the location of your web browsing preferences)"
- The site will then support cross-site preference lookup techniques by any website to learn the current domainname/time for that browser, and the cds.com server would echo back the values stored in the browser's cookie
- This service will need to be free, but will get heavy load for the cross-site requests, so we may need a neutral group/company similar to Verisign to run it (though they may in turn outsource the operations to someone like Google/Verisign/Microsoft)
- The statistics about the service will probably need to be made publicly available (such as usage levels and popularity of different personal discovery services)
- The CDS only needs to store a single small preference (it fits in a cookie) so it will scale easily.
- The CDS does not need a login system.
One partial alternative to the CDS is to define a standard URL parameter that can be used to pass a user's PDS. That way, if one site knows a user's PDS and is redirecting the user to another site, then it could pass that PDS information as a hint. In particular, a websearch or E-mail provider might learn of (or actually be) a user's PDS, and it could add that URL parameter whenever the user clicked a search result, and ad, or a link in E-mail.