SCF Reference Manual for G-Series RVUs (G06.24+)

Introduction to SCF
SCF Reference Manual for G-Series RVUs—520413-004
3-2
Subsystem Control Point (SCP)
SCF automatically opens and closes the SCP. In most cases, the default SCP is the
only one you need. If you need to establish an SCF session with a specific SCP other
than the default SCP, you can start additional SCP processes by using one of the
following:
•
An SCF RUN command
•
A TACL RUN command (as described in the Subsystem Control Point (SCP)
Management Programming Manual)
•
A generic process (as described in SCF Reference Manual for the Kernel
Subsystem)
To select a running SCP other than the default SCP, use the OPEN command
described on page 5-86 in this manual.
During the initialization of a system with a large number of communications devices, it
can be advantageous to have multiple SCF processes and multiple SCP processes
running at one time, but this use is limited to system managers and super-group
(255,n) users.
Subsystem Control Point (SCP)
The Subsystem Control Point (SCP) is a network management process for receiving
and redistributing the messages that SCF sends to its subsystems. SCP provides
security, version control, and tracing support for many of these subsystems.
SCP can be used in two ways, interactively and programmatically.
•
The interactive interface (using SCF) is provided so you can choose either to let a
person perform an action or to automate the action. The interactive interface is
described in this section under How SCF Works on page 3-4.
•
The programmatic interface is controlled by the Subsystem Programmatic Interface
(SPI), which builds and retrieves information from command, response, and event-
message buffers. SPI is described in the SPI Programming Manual.
The SCP programmatic interface (using software programs) is based on the
requester-server model and the use of tokenized messages (SPI messages) rather
than text. This basic interface is used for control and inquiry as well as for event-
management functions. The programmatic interface is fully described in the
Subsystem Control Point (SCP) Management Programming Manual.
When SCP receives a request, it performs a security check. SCP allows sensitive
commands to be used only by super-group users (255,n) or by users in the group that
created the subsystem. If the security check fails, SCP generates a security-failure
error response.
Next, SCP checks the subsystem destination. If the subsystem is not open, SCP
opens it. Once the subsystem is opened, SCP provides version control by comparing
the request version and the destination subsystem version. If the versions are not