Availability Guide for Application Design

Glossary
Availability Guide for Application Design—525637-004
Glossary-25
transaction-processing monitor (TP monitor)
transaction-processing monitor (TP monitor). An entity that provides a transaction-
execution environment on top of the operating system. See also Pathway transaction-
processing environment, and NonStop Tuxedo System /T.
transient error. A hardware or software error that is difficult to reproduce or that occurs in
an unpredictable way. These errors typically occur only when a specific set of
conditions coincide. Transient errors are sometimes known as soft errors. Contrast with
deterministic error.
trickle catchup. A technique for placing transaction requests on a transaction-protected
queue while the server system is unavailable. The server reads these requests from
the queue when it becomes available again before it accepts any new request from a
requester. This technique works for applications for which the order in which requests
are processed is important. Contrast with transaction playback.
Tuxedo System /T. See NonStop Tuxedo System /T.
Tuxedo /WS. The component of the NonStop Tuxedo transaction-processing environment
that extends transaction management to the client workstation.
two-phase commit protocol. A series of operations performed when a statement is
executed to commit a transaction. In the first phase, the after-image for the transaction
is written to the audit trail. In the second phase, locks held by the transaction are
released.
TX interface. In the X/Open Distributed Transaction Processing (X/Open DTP)
environment, the name of the application programming interface between the
application and the transaction manager. The TX interface allows portable applications.
It includes verbs to begin, commit, and abort a transaction.
UDP/IP. User Datagram Protocol/Internet Protocol—A set of layered communications
protocols used to send a datagram message from one computer to an application
running in another computer. Like TCP/IP
, UDP is used with IP (the Internet Protocol).
Unlike TCP/IP, UDP/IP is connectionless and does not guarantee reliable
communication; the application itself must process any errors and check for reliable
delivery.
unilateral abort. An abort caused by a participant in a transaction that is not yet in a
prepared state.
unknown state. The state of an object when it is not defined. To the application, the object
does not exist. See also up state
, down state, and odd state.
unplanned outage. Time during which the system is not capable of doing useful work
because of an unplanned interruption. Unplanned interruptions can include failures
caused by faulty hardware, operator error, or disaster. Contrast with planned outage.
See also outage, outage minutes, outage log, and availability.