Wcf – the best practice using NHibernate 3.0 with WCF Web Services

Actually, although I blogged (see Luke's answer), I think this is better than my IDisposable wrapper. Typical code:

Service<IOrderService>.Use(orderService=>
{
  orderService.PlaceOrder(request);
}); 

(edit per comments)

Since Use returns void, the easiest way to handle return values is via a captured variable:

int newOrderId = 0; // need a value for definite assignment
Service<IOrderService>.Use(orderService=>
  {
    newOrderId = orderService.PlaceOrder(request);
  });
Console.WriteLine(newOrderId); // should be updated

Creating your ISession and disposing it explicitly inside your repositories like that is ok for small and very simple projects - but, as you have found out, it comes short when you start wanting to use some of the cool features that NHibernate supports.

You should probably let the lifestyle of the session be controlled by something outside of your repositories - e.g. if you are doing ASP.NET web applications, you might want to save the session in the current request (HttpContext.Current.Items if I recall correctly) for the duration of the web request, and then commit and dispose at the end of the request (or rollback if an exception occurs).

I don't know the best way to control the lifestyle of your session in ASP.NET applications, but there must be some way to have code called at the beginning and at the end of each request. In ASP.NET MVC it can be easily accomplished by deriving all your controllers from a base controller that has overriden its OnActionExecuting and OnActionExecuted methods.