Our application is designed with businesslogic layer and data access layer. The business logic layer is wrapped in a webservice.
The front end is ASP.Net and it will interact with the business logic layer through the webservice call. Session handling and transaction handling is handled in the data access layer.

In the dataaccess layer we use Open session, Read / write the data, close session.

I have couple of questions with respect to the above design.

1. Will there be any performance hit if i go with the above design with respect to Nhibernate.

2. How are the table locks being handled with respect to the above design?
will the hibernate sessions handle the locks or should i need to handle it explicitly?

Any suggestions on improving the performance??

Thanks
Vijay