CNM interface

Using the CNM interface, an application program can communicate with the VTAM® SSCP to acquire information from physical units (or to send information to physical units) in session with the SSCP. This communication is made possible by two processes:

The SSCP and the PU exchange information through an SSCP-PU session.
The application program and the SSCP exchange information over the CNM interface.

In most cases, the application program and the SSCP communicate over the CNM interface by using Forward and Deliver request units (RUs). A Forward RU places in a “data envelope” all data or requests for data that the application program wants sent to the PU in session with the SSCP. The SSCP transmits the data or the request for data to the PU through the SSCP-PU session. Similarly, the PU replies with the requested information (or provides unsolicited information) through the PU-SSCP session. A Deliver RU places the data provided by the PU in a “data envelope.” The SSCP then sends the Deliver RU to the application program over the CNM interface.

Some communication between the application program and the SSCP over the CNM interface can use a group of request units that are not embedded in Forward or Deliver RUs. For example, the TR-INQ (Translate Inquiry) RU and the TR-REPLY (Translate Reply) RU can be passed to or sent by the CNM application program without embedding Deliver RUs. See Types of network services request units not embedded for more information about these RUs.