Using CICS intercommunication

The CICS® intercommunication facilities allow you to implement many different types of distributed transaction processing. Some examples of typical applications are explained.

Multiregion operation allows two CICS regions to share selected system resources, and to present a “single-system” view to terminal operators. At the same time, each region can run independently of the other, and can be protected against errors in other regions. Various possible applications of MRO are described in Multiregion operation.

ISC over SNA, using the ACF/SNA access method and ACF/NCP/VS network control, allows resources to be distributed among and shared by different systems, which can be in the same or different physical locations.

IPIC connections allow you to use a TCP/IP network for intercommunication between systems. IPIC provides similar capabilities and qualities of service to those provided by ISC over SNA.

Figure 1 shows some typical possibilities.

This picture shows two ways of using CICS intercommunication to distribute resources, as discussed in the text. The first example is entitled “Connecting regional centers”. It shows three CICS regions, named North, Central, and South. Each region supports a network of terminals and has its own database. The regions are connected by intercommunication links. In this example: The corporate database is partitioned by area. The same applications run in each center. All terminal users can access applications or data in all systems. Terminal operators and applications are unaware of the location of data. The second example is entitled “Connecting divisions: distributed applications and data”. It shows three CICS regions, named Headquarters, Warehouse, and Plant. Each region supports a network of terminals and has its own database. The Headquarters' database is named “Financial and Planning”, the Warehouse database is named “Inventory”, and the Plant database is named “Work Orders”. The Warehouse and Plant regions are connected to the Headquarters region by intercommunication links. In this example: The corporate database is partitioned by function. The applications are partitioned by function. All terminal users and applications can access data in all systems. — Figure 1. Examples of distributed resources (Part 1)

This picture shows two further ways of using CICS intercommunication to distribute resources, as discussed in the text. The first example is entitled “Hierarchical division of database”. It shows four CICS regions, named Head Office, Plant A, Plant B, and Plant C. Each region supports a network of terminals and has its own database. The Head Office database is named “Summaries and Planning”; the Plant databases are each named “Parts, Cross-Reference, and Work Order”. The Plant regions are connected to Head Office by intercommunication links. Over these links, orders and schedules are sent from Head Office to the Plants; production status reports are sent from the Plants to Head Office. In this example: The corporate database is partitioned hierarchically. Summaries and central data are held at Head Office. Detailed data is held at the Plants.Orders are processed at Head Office. Then schedules of work are sent to the Plants for manufacture and shipping of orders to customers.The Plants send summaries of production status to Head Office.If necessary, operators can access data from Head Office or the Plants.The second example is entitled “Hierarchical division of data and applications”. It shows three CICS regions. Two of these regions handle high-priority applications and data; the third region handles low-priority applications and data. Both the high-priority regions support a network of terminals and are connected to the low-priority region by intercommunication links. Each region has its own database. In this example: The corporate database and applications are partitioned hierarchically, according to the priority of the information handled.The two high-priority regions support the same applications. Multiple regions gives improved response times.If necessary, terminal users attached to the high-priority regions can access the low-priority applications, by routing from the high-priority regions. — Figure 2. Examples of distributed resources (Part 2)