One common question we come across is "how does an offline app establish a connection between a user in the offline system and a HealthVault user?"
Partner applications that use offline access currently need a portal page that uses online access. The user authenticates into that page, authorizes access to the application, and then the portal page records the user id and record id. It can then save those two values (both guids) in the record for that person, and use them to connecto that person's HealthVault record.
Because having to create a portal application just to do this is a bit clumsy, we are considering adding a platform feature where the offline system would "register" an identifier that lets them know who a patient is with HealthVault, and HealthVault would return a validation code to the system. The user could then go to HealthVault, select the appropriate application, and enter that validation code, which would be recorded.
At a later time, the offline system can query in to find if there are any new validations ready for it. It will then get back the identifier it registered along with user id and record id, and at that point it could use offline access.