Closing connections explicitly in Entity Framework

Question

Reading the microsoft documentation http://msdn.microsoft.com/en-us/library/bb738684.aspx I see they explicitly open and close the connection

using (EntityConnection conn = new EntityConnection("name=AdventureWorksEntities"))
{ 
    conn.Open();
    ...
    conn.Close();
}

why is this necessary?

Answer 1

This isn't the "normal" way of using EF. EF usually manages the connection for you. However:

Managing Connections in Object Services (Entity Framework)

Object Services exposes the EntityConnection by means of the Connection property. This enables you to manage the connection and transactions or to supply your own EntityConnection. This is useful when you want to hold open a connection within a short-lived object context to improve performance or to explicitly control transactions. The same provider connection used by the Entity Framework can be shared with other parts of an application.

The following considerations apply when managing connections:

• The object context will open the connection if it is not already open before an operation. If the object context opens the connection during an operation, it will always close the connection when the operation is complete.

• If you manually open the connection, the object context will not close it. Calling Close or Dispose will close the connection.

• If the object context creates the connection, the connection will always be disposed when the context is disposed.

• In a long-running object context, you must ensure that the context is disposed when it is no longer required.

• If you supply an open EntityConnection for the object context, you must ensure that it is disposed.

So in short, normally you don't manage the connection, but if you want to do it manually for the reasons stated above, you can. If you decide to open the connection manually, you need to close it manually (EF doesn't make any assumptions for you if you decide to go manual).