Add user session id to logs

[baszoetekouw]

In Engineblock, we can trace the user through the system based on the user session id. We also want to be able to trace which PDP-events (request, decision and any errors) are carried out in the user's journey through the login process.

So, we want to add the user session-id to the PDP requests from Engine to the PDP. The PDP should then add this session-id to all logging related to this request.

For backward-compatibility, the PDP should gracefully handle the case that no session-id is sent, and log a null-value in that case.

The way in which the session-id is trasnmitted in the PDP-request is to be determined. I see two possibilities:

• add it as part of the XACML requests, for example in a new Environments or IntermediarySubject section
• add it as extra GET parameter on the decision request
• add it in some other (custom) HTTP header

We need to check how SSID handles this.

[baszoetekouw]

@pmeulen How is the user session passed between Engine and SA-gw? Do you put it in the SAMLRequest or do you pass it out-of-band?