Both the CDS and the PDS need to allow other sites to request publication of information. The publication request should not require prior registration of the requesting site. Publication will work as follows:
1. The publisher site will ask the user for permission to record a preference. "Use your Gmail account to login to other websites without having to create more passwords."
2. If the user indicates they would like the preference to be saved, the publisher site will redirect the user (probably in a pop-up window) to the discovery site. The redirect URL will include the information to be published.
3. The discovery site will ask the user to confirm the publication. "Please confirm you would like all the websites you visit to be able to determine that gmail.com has your web browsing preferences."
4. If the user confirms the publication, the preference will be recorded and made available via the discovery service. The user will automatically be redirected back to the publisher site.
5. If the user does not confirm the publication, they will be shown a message stating that the preference has not been published. The user will have the option of clicking a link to return to the publisher site.
Note that the CDS and the PDS do not need to trust the publishing sites, nor do they need to exchange any sort of API key with the publishing sites. Trust is established by asking the user to confirm the data being published.