Addressing OLTP Solutions with CICS: The Transaction Server ... - Ibm

Figure 9. Interconnection Using Encina PPC TCP/IP Support
3.3.3 SNA
34 CICS for AIX as the Transaction Server
When an intersystem request is made, the name service is used to locate the
required region. A connection is then set up between the two systems and used
exclusively by the intersystem communication requests. The connection is
closed down when the request has completed. Depending on the frequency of
the requests, a lot of session startup and shutdown processing could be
involved. If this is the case, consider using CICS family TCP/IP where the
connection remains for as long as the two systems are active. Synchronization
levels 0, 1, and 2 are supported with Encina PPC TCP/IP.
With SNA, proprietary network architecture from IBM, the end points of
conversations operate as logical entities, or a logical type of device. Thus, a
piece of code can communicate in the same manner as an actual device and so
appear to its partner in the conversation to be a device. SNA is widely used in
IBM mainframe-based systems. It is also now available on a number of
UNIX-based systems such as AIX. It is implemented on these systems through
products such as SNA Server for AIX. The availability of SNA on these
UNIX-based systems facilitates communication between the UNIX-based systems
and applications that run on mainframes.
CICS for AIX regions can communicate across SNA with any APPC-capable
system, including:
• Other CICS on Open Systems regions
• IBM CICS clients
• CICS for OS/2 regions