Question

I’m a beginner at both NHibernate and Castle Windsor but the current application I’m working on is making use of Castle Windsor’s NHibernate facility Integration level 2 i.e. using the ISessionManager.

I’ve compared what I need to do in order to manually persist my data and using ISessionManager and I’m not really writing less code. My question is why do I even need ISessionManager? What advantages is it offering me? What are the disadvantages of using ISessionManager?

Answer 1

Well first of all, you don’t have to manage sessions yourself. In a web-enviroment you typically want to scope your sessions pr request. The session manager ensures that the first caller to “OpenSession” starts a new session, while nested invocations gets the same session when invoking “OpenSession”. You can do the same yourself by staring/closing sessions in a httpmodule or using an AOP pattern, note that doing this implies that your are working against one database, handling multiple databases yourself gets a bit more tedious. ISessionManager handles multiple databases just as tidy as it handles one.

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Handles sessions for you
Lightweight, non intrusive
Simple
Easy support for working against multiple databases
Hosting agnostic (works just as well with nservicebushosting as it does with IIS)

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A bit more boilerplate code in your DAL/Repositories/whatever you call it