Using session data across applications and subdomains

Question

Is there a way to share session <b>data</b>
across different CF applications? across different subdomains?
The goal here is single source login that stores complex data
in a re-useable session scope. The current installation uses wddx
to serialize the data and drop it into a cookie. I am looking for
alternatives to the WDDX method as it has been causing a number of
errors.
For example I have application "a" at appA.domain.com ~ a
user logs in an a session is created [domain cookies are set].
I would like the user to be able to go to both
appA.domain.com/subapp [which has its own application.cfm] and
reuse the session created at appA.domain.com.
Similarly I would like the session created appA.domain.com to
carry over to appB.domain.com [which would has its own
application.cfm file].
Thanks for any help.
~jason.

Answer 1

That would be known as cros-site scripting and most browsers
disable that now, as it is a security issue if an application can
read cookies from a different site domain.
Sites that use cross-site data have to either pass it at the
time accessig the other domain (via URL) or use a single database
to record and recall data between applications.
Passport is a good example. Even though you can use Passport
on any site that offers it, the site ultimately tranfers you to the
Passport website momentarily to collect your login and then
transfers you back to your site along wth the credentials in a URL
variable so your own site can then record the cookie and state you
are logged in. It doesn't actually read the Passport cookie from
your own site.
If you were to create a DB that applies to multiple sites,
you could figure out a way to populate session variables on
separate sites by quering the DB for the data if there is no data
currently stored, or if it detects that the referer was a different
URL prior to loading the current site. Once it queries the data it
can store the data in a session variable.