NHibernate.Session

Target Framework = 3.5, 4.0, 4.5

NHibernate = 3.3.3.4000

The NHibernate.Session.Marshaler is an ISession context provider for NHibernate. It is a simple process to create a unit of work implemenation that works identically in web (per request) or per process level environments. The only difference is that in per process environments, a commit will also spin up a new transaction so that processing can continue. This can be useful in a check-point restart pattern for batch processing.

The marshaler can wrap a singleton session in cases where you need multiple session factories. This can be useful for batch automation programs that need to use the same infrastructure initialization configuration.

The marshaler can create stateless sessions for cases where 1st level cache is not needed.

The Marshaler uses the NHibernate.Context.WebSessionContext when HttpContext is detected, otherwise NHibernate.Context.ThreadStaticSessionContext is used.

Typical setup:
Note: I hate statics, so I create an IUnitOfWork interface and use my favorite IoC framework to handle binding the UnitOfWork. This isolates the UnitOfWork to the infrastructure tier, and the IUnitOfWork is the dependency for other types (i.e. Controllers). This allows the Controllers to be tested in isolation with a mocked IUnitOfWork.

//Create a unit of work wrapper for each session factory you need (typically only one)
public static class UnitOfWork
{
    private static NHibernate.Session.Marshaler _marshaler;

    public static void Initialize(NHibernate.Session.Marshaler marshaler) { _marshaler = marshaler; }

    public static ISession Session { get { return _marshaler.CurrentSession; } }

    public static bool HasSession { get { return _marshaler.HasSession; } }

    public static void Commit() { _marshaler.Commit(); }

    public static void End() { _marshaler.End(); }
}

//In Global.asax:

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    RegisterGlobalFilters(GlobalFilters.Filters);
    RegisterRoutes(RouteTable.Routes);

    var config = new NHibernate.Cfg.Configuration();
    //... setup your configuration

    //instantiate a single NHibernate.Session.Marshaler for each factory (again, typically only one)
    var marshaler = new Marshaler(config);

    //initialize the unit of work wrapper
    UnitOfWork.Initialize(marshaler);
}

void Application_EndRequest(Object source, EventArgs e)
{           
    UnitOfWork.Commit();
    UnitOfWork.End();               
}

//usage:

var c = new Cat("meow") 
{ BirthDate = DateTime.Now.AddYears(-2), Gender = "Female", Name = "Fluffy" };
UnitOfWork.Session.Save(c);