With the new cookie laws in the EU, it's getting a lot harder to track users. There have been changes already, but what I'm proposing will effectively make sure piwik can almost always be used.
One of the parts of the new law is that so called essential cookies don't need permission. Every site with a login system will be able to use a session cookie, since it's essential to the functionality of the site. If piwik were to use that session cookie, it wouldn't need to set its own. At the moment multiple cookies are set, but having something is a lot better than nothing. Of course people can still opt out.
I don't know if this is even possible, but it would be a big plus for piwik.
Sorry I didn't understand the idea of using session cookie to replace piwik cookies?
If I understand well, the idea is to use http://en.wikipedia.org/wiki/Session_ID.
However, session IDs have short TTL and/or are invalidated and therefore do not span visits.
Please elaborate if you think we are missing something.
Replying to JulienM:
If I understand well, the idea is to use http://en.wikipedia.org/wiki/Session_ID.
Correct
However, session IDs have short TTL and/or are invalidated and therefore do not span visits.
The system you are running has control over how long the cookie lives and whether or not you invalidate the ID. With PHP the lifetime is set to 0 by default, which means it's valid for the session. But you can change that to something else.
I do not think many users would go down that road as increasing lifetime of session cookies is insecure.
Should this ticket become a feature request ?
It was filed as one.
Do whatever you want, it was just an idea :)