Availability Guide for Application Design

Glossary
Availability Guide for Application Design—525637-004
Glossary-23
Subsystem Programmatic Interface (SPI)
Subsystem Programmatic Interface (SPI). A set of procedures for building and decoding
commands, responses, and event messages.
sync depth. A parameter that sets the maximum number of operations or messages that a
process is allowed to queue before action must be taken or a reply must be performed.
synchronization block. A data block containing a synchronization identifier. This
synchronization block is checkpointed to the backup process along with the data it is
synchronizing. See synchronization identifier.
synchronization identifier. A value that is maintained in an application process and in the
disk process to make it possible to retry some operations that would be otherwise
nonretryable, such as partial sector disk writes.
Systems Network Architecture (SNA). The prevalent IBM communications model.
Syshealth. A maintenance and diagnostic software package that polls devices and monitors
system events on HP NonStop systems. When a problem occurs, Syshealth generates
an alarm describing the problem and sends notification to a remote site.
TandemTalk. A reliable communication protocol between HP NonStop systems and
Macintosh computers.
TCP. See terminal control process (TCP).
TCP/IP. Transmission Control Protocol/Internet Protocol—A set of layered communications
protocols for connecting workstations and larger systems. See also UDP/IP.
TCP requester. A COBOL program that runs as one thread in a TCP and makes requests
of a Pathway server process. See also COBOL and terminal control process (TCP).
TDP. See Transaction Delivery Process (TDP).
terminal control process (TCP). A process responsible for terminal management and
transaction control, provided by HP as part of the Pathway/iTS product. A TCP is a
multithreaded process that interprets the COBOL requester programs in the user’s
application, executing the appropriate program instructions for each I/O device or
process the TCP is configured to handle. The TCP coordinates communication
between COBOL programs and their I/O devices or processes and, with the help of the
PATHMON process, establishes links between screen programs and server processes.
See also requester and COBOL.
TFDS. See HP Failure Data System (TFDS).
thread. A unit that can be separately dispatched and that represents a sequential flow of
control within a process. A COBOL program executing within a terminal control
process (TCP) is an example of a thread.
TLAM. See HP LAN Access Method (TLAM).