The client application uses the Link3270 bridge to run 3270 transactions by linking to the DFHL3270 program in the router region and passing a COMMAREA that identifies the transaction to be run and contains the data used by the user application. The response contains the 3270 screen data reply. If the target application used BMS, this is presented in the form of an application data structure (ADS), another name for the symbolic map that is generated by the BMS macros used to define the mapping of the 3270 screen.
The Link3270 bridge is called in the same way for all request mechanisms of the interface: EXEC CICS LINK, the EXternal CICS® Interface (EXCI), and the CICS External Call Interface (ECI).
The following flow describing the Link3270 mechanism is shown also in Figure 6:
The Link3270 mechanism supports non-conversational, pseudoconversational and conversational applications.