The CICS® Transaction Gateway supports the integration of CICS servers and client applications. There is a standard set of functions to allow user applications to call CICS programs, initiate CICS 3270 transactions or perform password expiry management (PEM).
Three Application Programming Interfaces (APIs) are available to enable user applications to access and update CICS facilities and data. These are the External Call Interface (ECI), the External Presentation Interface (EPI) and the External Security Interface (ESI).
There are also statistical data APIs, which enable a user application to collect statistical information about a running CICS Transaction Gateway.