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

egion or server it is looking for. If the server or the region does not exist on that
host, hostB is searched, and finally hostC if required. Optionally for CICS Client
for AIX, the host name of the CICS for AIX region may be specified on the
cicsterm command.
When any CICS region or Encina server is moved from one system to another,
the $CICS_HOST variable must be updated on those systems which access that
CICS region or Encina server. This scheme lacks the flexibility that DCE CDS
has. Additionally if there are many host names specified in the $CICS_HOST
variable, the search time to locate a CICS region or Encina server will be longer.
Figure 21 shows a simple configuration consisting of two systems, host 1 and
host 2. DCE CDS and security are not in use in this configuration. The DCE RPC
daemon is still required on each system so that a client can call a server.
Figure 21. Configuration without DCE CDS and Security Services
As DCE is no longer in use there is no requirement for a DCE server and so
there are no DCE clerks on each of the client nodes.
In this configuration users must authenticate themselves to a CICS for AIX region
by using a CICS userid and password.
5.3 Planning Considerations for DCE
74 CICS for AIX as the Transaction Server
As the use of DCE CDS and security are optional, you must first decide whether
to use them or not. We strongly recommend using DCE CDS and security for the
following reasons:
• DCE provides a common, standards-based infrastructure across multiple
vendors for distributed processing. Installations are typically multivendor.
Software that is multivendor can simplify the process of administration and
reduce the administrative overhead. It is possible to operate the mixed
environment as a single DCE cell.
• DCE security provides comprehensive security facilities. The security
facilities cover authentication, authorization, data integrity, and data
encryption. CICS for AIX in comparison only provides limited authentication
facilities. We recommend combining the DCE and CICS security methods.
• DCE CDS provides dynamic server location for requesting clients. In a
complex environment where servers may move as configurations change or
processors are upgraded, for example, the administrative overhead of doing
server location is reduced. CICS for AIX does provide facilities for allowing
clients to access to servers. Manual intervention is required, however, when
a server is moved, to ensure that the clients can locate the repositioned
server. This could become a significant overhead when a CICS for AIX