Transaction Routing

XCICS transaction routing allows terminals connected to one XCICS/CICS system to run with transactions in another connected XCICS/CICS system. This means that you can distribute terminals and transactions around your XCICS/CICS systems and still have the ability to run any transaction with any terminal.

The system that owns the terminal is called the terminal-owning region or TOR, and the system that owns the transaction is called the application-owning region or AOR. These terms are not meant to imply that one system owns all the terminals and the other system all the transactions, although this is a possible configuration.

The terminal-owning region and the application-owning region must be by APPC links.

The user transaction can use the terminal control, BMS, of XCICS to communicate with the terminal, as appropriate for the terminal or session type. Mapping and data interchange functions are performed in the application-owning region.

The transaction routing feature can be successfully employed in the following scenarios.

Multiple server systems (Cluster)

The architecture of XCICS does not require the creation of a pool of regions to make use of all the power provided by a single SMP computer, because every XCICS region can use effectively more than one CPU.

In some situation, you want to use the power of more than system: this is the case of a cluster. In this scenario one ore more XCICS regions runs on every machine of the cluster, each one serving a part of the application. The terminal users will connect to one region (TOR), which will route the transaction requested to the corresponding server.

Partial or progressive re-hosting

In the case of a partial re-hosting of a mainframe system (only a part of the applications running on the mainframe are moved to UNIX/Linux or Windows) or in the case of a progressive re-hosting (applications are moved one next the other to the UNIX/Linux/Windows system), the transaction routing can be successfully used.

In this situations XCICS normally acts as AOR, serving transactions for the TOR (the old mainframe application), reducing the work-load of the mainframe system.

Of course a reverse scenario could also be possible, using XCICS as TOR and IBM CICS as AOR.