Handle multiple virtual hosts differently

[Christoph Schönfeld]

Hi,

I tried several days to get the following setup working, but something 
is missing.

First of all, let me explain what I am trying to accomplish.
I have installed an IdP and a SP on two different hosts. The SP machine 
uses apache and the SP apache module. In the apache configuration I set 
up two different vhosts with different domains. Let's say a.example.com 
and b.example.com.
The IdP should handle both vhosts. The problem I run into, is that I 
want to differ between logins from a.example.com and b.example.com. If a 
user authenticates for a.example.com he should not be able to access 
resources under b.example.com.

I configured both vhosts to be separate applications with different 
entityID's and thought this would be enough to distinct between the 
sessions. Finally, I want to use different ldap configurations for 
authentication and attributes per SP, but that's another topic.

At the moment, if I login to one of these resources, I am automatically 
logged into the other one too. Is there any way to configure this 
behaviour? Is it possible with a single IdP instance?

Any help would be appreciated