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

3.1.3.1 Terminal Users and CICS Regions
Terminal users request services from CICS regions (servers) as clients. A CICS
for AIX region can be accessed by the following CICS clients:
• CICS Client for AIX
26 CICS for AIX as the Transaction Server
• CICS Client for Sun Systems
• CICS Client for Windows
• CICS Client for DOS
• CICS Client for Macintosh
Therefore even in an environment where users have mixed hardware with a
variety of operating systems, CICS for AIX can act as an application server. This
protects the investment in existing hardware while still allowing investment in
new technology. The CICS clients are discussed more fully in Chapter 4, “Using
CICS Clients” on page 49.
3.1.3.2 Encina Servers and CICS Regions
CICS can use the Encina PPC Gateway for intercommunication across an SNA
network. See 3.3.3, “SNA” on page 34 for more details. The Encina SFS can be
used for CICS queue and file management. CICS for AIX V2.1 introduces the
option of holding CICS queues and files within DB2. The Encina components are
covered in more detail in Chapter 6, “Interactions with Encina for AIX” on
page 77.
3.1.3.3 DCE Services
CICS can optionally be configured to use DCE security services and Cell
Directory Services (CDS). The DCE security service is used to authenticate
users. CDS are used to help clients locate servers. The use of DCE by CICS is
covered more fully in Chapter 5, “Interactions with DCE” on page 69.
Note: Alternatively an installation may wish to use encrypted passwords for
CICS userids and manually set up end-point mapping for the regions, the SFS,
and any PPC gateways instead of using DCE security services and CDS.
3.1.3.4 CICS Regions and CICS Regions
CICS for AIX regions can communicate with other systems. Thus users of a local
region can access services that are available on a remote system. In this case
the local region is the client, and the remote region, the server. Alternatively
users of a remote system can access services available on the local region. In
this case the remote region is the client, and the local region, the server. This
CICS-to-CICS intercommunication provides an effective and flexible base for the
implementation of distributed client/server processing.
CICS-to-CICS intercommunication can take several forms. In general it is
implemented such that applications or users are unaware that the resources
they are using are located on a remote system. The intercommunication
facilities are:
• Distributed program link (DPL)
DPL enables a program to link to another program that resides on a different
system. This can be useful where there is a large amount of data to be
manipulated. The manipulation can be performed close to the data location,
and the result returned to the local system. This saves having to transport
all of the data to the local system.
• Function shipping