Invoking CICS Programs Externally

The client program for your CICS application need not run in a CICS region, and need not use BMS. You can invoke your CICS programs externally via a graphical or Web user interface that is written in Java, Cobol, C, or runs under Microsoft .NET or uses Dialog System. You achieve this using the External Call Interface (ECI) and (External Presentation Interface (EPI), which allow non-CICS programs to interact with CICS programs and transactions.

Enterprise Server supports standard ECI and EPI calls to Mainframe Subsystem enterprise server instances. ECI allows non-CICS programs running outside the server to invoke COMMAREA-based CICS programs within a region. EPI allows non-CICS programs to initiate 3270-based CICS transactions and send/receive associated data. Both ECI and EPI facilitate the opening up of access to legacy business logic.

Which Middleware?

Micro Focus provides two methods of communicating with CICS applications running under Enterprise Server. These are: IBM CICS Transaction Gateway (CTG), and Micro Focus ECI. You need to determine which of these two methods best suits your requirements.

IBM CICS Transaction Gateway
IBM's CICS Transaction Gateway (CTG) is a full function connector, allowing a wide range of application platforms to connect to CICS. If you require all the features provided by CTG, then you may wish to choose this product. However, consider these factors:
  • You require an IBM CTG license
  • You need to install and configure CTG on each client machine, unless you link the CTG module into your client program

For more information, refer to the IBM publication CICS Transaction Gateway for Multiplatforms.

Micro Focus ECI
Micro Focus provides a no-cost ECI emulator as part of Enterprise Server. Being an integral part of the product, you do not need to install or configure any additional software. This emulator has a simpler feature set, and supports the following:
  • COBOL ECI LUW and ELUW
  • COBOL ECI client with ES region on the same local machine and shared memory link between client and server
  • COBOL ECI client with ES region on a local or remote machine and TCP/IP link between client and server
  • Java ECI LUW and ELUW with SSL
  • Java ECI client with ES Server on a local or remote machine and TCP/IP link between client and server
  • Additionally, Java ECI clients can invoke CICS programs passing data either in a Commarea or in a Channel and its associated Containers.
  • Non transactional Java Connector Architecture based resource adapter. Java ECI clients run in Java AS. Support for Websphere 8.5 and JBoss 7.1
The following restrictions apply to this implementation:
  • No JVM COBOL
  • No SSL for COBOL ECI clients
  • No support for External Presentation Interface (EPI)
  • No support for External Security Interface (ESI)
  • No workload management
Parent topic: About CICS applications