Windows Communication Foundation: Problems with session based serv

[Kottan1970]

I have a problem to establish a WCF Service with a transport level session
(SessionMode=SessionMode.Required, InstanceContextMode =
InstanceContextMode.PerSession) and the following prerequisites :

Webserver: IIS 6.0

Web.config:

- wsHttpBinding
- security mode="Transport" (https)
- transport clientCredentialType="Certificate"

ServiceContract: SessionMode=SessionMode.Required

ServiceBehavior: InstanceContextMode = InstanceContextMode.PerSession


Using this configuration I get the following error:

"Contract requires Session, but Binding 'WSHttpBinding' doesn't
support it or isn't configured properly to support it."

It seems like I can not use server ServiceContract SessionMode.Required with
<security mode="Transport" >

I have read that a session based WCF service is only possible with
reliability (reliableSession enabled = true) or message security
(whereas I don't want to use message security).
Unfortunately it also seems, that wsHttpBinding cannot be combined with
reliableSession and transport security (SSL).
So enable reliableSession only works for http (but I need to use transport
security, among others to verify client's x509 certificate)

The only workaround that I found is the usage of ASP.NET compatibility and
the HttpContext object ! This works fine !

Does anybody know other solutions for that problem or is it better to use
NetTcpBinding with IIS 7 ?
Does NetTcpBinding work together with x509 certificate verification ?
Has anybody source examples for secure session based WCF services ?

Thanks in advance !