This method requires an additional ESL application to handle all the coordination of the sessions. This method works best if all the applications involved support DDE or are ESL applications. The applications can use the additional server in two ways:

Each application can request a transaction to be executed by the 3270 server, which executes the proper 3270 routines and returns the results to the client application.

An additional server application can keep track of the applications that are using each session. For this situation, the second application is an invisible DDE server that performs EcsConnect and EcsDisconnect subroutines, but does not perform other 3270 communications. When an application needs a specific session, it sends the message to the server. The server then checks to see if that session is in use. If it is in use, the server sends a disconnect message to the other application in the current session. After that application disconnects and notifies the server, it then tells the original application that the session is free.