Expand Management Programming Manual

SECTION 4
ELEMENTS OF SPI MESSAGES FOR THE EXPAND SUBSYSTEM
The Subsystem Programmatic Interface (SPI) is used for building
commands to, decoding responses from, and obtaining event mes-
sages issued by the EXPAND subsystem. The procedures used
by an application to perform these tasks are described in the
Distributed Systems Management (DSM) Programming Manual . Using
SPI messages to communicate with the EXPAND subsystem through SCP
is described in the Communications Management Programming Manual .
The commands, responses, and event messages that are sent to
and received from the EXPAND subsystem are made up of special
codes called tokens. Each token contains a particular piece
of information, such as the command number of a command or one
element of an event message. Tokens can be single values or
structures consisting of several values, and some tokens, called
header tokens, are present in every command, response, or event
message.
This manual does not attempt to give a complete explanation
of tokens; it provides subsystem-specific information about the
tokens used to communicate with the EXPAND subsystem. General
information about tokens can be found in the Distributed Systems
Management (DSM) Programming Manual , and information about tokens
that is common to all data-communications subsystems can be found
in the Communications Management Programming Manual .
This manual uses DDL to describe all tokens. For a quick
explanation of DDL as it applies to SPI, refer to the appendix
"Overview of DDL for SPI" in the Distributed Systems Management
(DSM) Programming Manual .
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