WCF and web client authentication issues.

[Maxus]

Hi People!

I'm building a SOA style application that contaisn a DB->Data Access
Layer->Business Logic Layer->WCF service. From there I will have three
types of clients: a web application, a win forms application, and a
compact framework application.

My question relates to authentication between the web application and
the WCF application. Currently my users are stored in the SQL database
and I'm using a custom authentication policy as suggested by P&P. The
part I'm having difficulties with is how to pass the username and
password to each instance of the WCF client created by the website and
where to cache the credentials (or even if to cache them). I wonding
if anyone had experiance with this and could offer some insight?

Thanks!
Maxus