If I decide to use session per request in ASP.NET app in order to enable lazyloading, I endup cached all the objects in Session for the request. Which is not very comfortable. Is there anyway to disable the cache thing? Caching object in the whole request is kindof dangerous.

Why do you feel it is dangerous?

If some other user changed the data, but my data is cached in Session, I got bogus data.

It's very common I have more than 2 requests at the same time in an ASP.NET application.

But you close the session at the end of the request, so the next request gets the up-to-date data.

Also, that's the whole point of using transactions - transaction isolation property means that you can program as if you were the only one accessing the database at a given time, and in the rare case of a conflict or another problem you roll back the entire transaction and tell the user to try again.

But this means in the same request, your data is cached. If you have 2 seperate transactions in one request, your data is in danger.

Well, if you often have to process two unrelated transactions in one request, you will have to design your application differently and open two sessions during the request.

The real problem is NOT that I have 2 transactions in one session, though it could be the case.

Typically you have 2 phase in a request:

Update Data

Load data and render your page.

The second phase is supposed to pick up the latest data. What about another request updated the data after you updated your data?

The rendering process really should NOT be in the same transaction in your updating process, and a transaction really should NOT be that long.

You could call the Clear method on the NH session between the update and the select if you wanted to use the same session instance and still have up-to-date data.

Alternatively as Sergey said, you could use two separate NH sessions - one for the update, and one for the select. When using a service layer to serve your UI layer this tends to be the case anyway as NH sessions are usually created and destroyed within each service layer call.