Connection definitions provide WebSphere MQ Everyplace with information on how to locate and communicate with remote queue managers. The name of a connection definition is that of the remote queue manager to which it describes a route, thus there may only be one direct connection definition for a remote queue manager. As connection definitions define the WebSphere MQ Everyplace network they are held in permanent storage in the registry and therefore persist across instances of the queue manager.
The route created using a connection definition uses an internal object called a channel as the transport mechanism to send data between two queue managers. Channels may not be accessed directly by a user but configuration decisions made for a queue manager affects the behavior of a channel. Refer to Communication Channel Security Considerations in Security for more information.
At the lowest level of the communications layers is the communications adapter. The reason they are mentioned here is that it is imperative the connection definition defines the same communications adapter class as the adapter class being used by the listener on the listening queue manager. If the communications adapters are not exactly the same a successful connection will not be made.