What are Disconnected ORM and Connected ORM

Question

Could any body clarify these two expression for me ?

What are cons and pros of each one ?

// I've just worked and familiar with CodeSmith and Linq to sql among all ORM Tools

Thank you

Answer 1

It refers to whether you can disconnect the database session and still expect the entities to be "alive". In disconnected ORMs you can disconnect and reconnect a database session (e.g. between web page requests) while retaining entity objects (e.g. in a web session state).

Personally I prefer not to work in disconnected mode (I'm mostly using NHibernate), because although it seems to simply things there will sometimes be side effects that are tricky to debug.

Answer 2

Well here are some cons to maintaining a connection to your database for an increased length of time:

1. memory on the database to maintain the connection
2. tying up a connection from the pool, which may be a finite resource
3. concurrency issues due to locking data

Convenience might be a pro.