TCP/IP TELNET Management Programming Manual

How a Management Application Fits Into the Architecture
Management Programming for the TELNET Subsystem
2–2 53474 Tandem Computers Incorporated
How a Management
Application Fits Into
the Architecture
A management application uses Subsystem Programmatic Interface (SPI) messages to
communicate with the TELNET subsystem. These messages are passed between the
management application and the TELNET subsystem by means of the Subsystem
Control Point (SCP) or the EMS interface. The function of an SPI message determines
whether the message is passed through SCP or EMS. SCP is a management process
that provides the control-and-inquiry interface. EMS is a collection of processes, tools,
and interfaces that support the reporting and retrieving of event information.
The control-and-inquiry interface differs from the EMS interface in key areas. For
instance, the control-and-inquiry interface requires that the management application
initiate communication with the subsystem by sending a command through SCP to the
subsystem. The subsystem then returns the appropriate response to the application
through SCP. This means that the exchange of a command and response between
your application and the subsystem is bidirectional and occurs synchronously. The
commands available to you for managing the TELNET subsystem are listed in Table 2-
1 in the next subsection, “Commands.”
Unlike the control-and-inquiry interface, the EMS interface requires that the subsystem
initiate communication. The subsystem reports event information when events
happen, not in response to a request from a management application. The
communication between EMS and your management application is unidirectional and
occurs asynchronously. Using EMS, a management application can monitor events
that occur in the TELNET subsystem. This enables the application to handle problems
that occur in the subsystem or to track the current status of the subsystem. An
application can then retrieve the event messages from the consumer distributor
process. If you want your application to retrieve specific information only, you can
write a filter. Figure 2-1 shows how a management application fits into the TELNET
subsystem architecture.