IPX/SPX Programming Manual

Glossary
HP NonStop IPX/SPX Programming Manual—528022-001
Glossary-17
UDP
UDP. (User Datagram Protocol) The Internet standard protocol that allows an application
program on one machine to send a datagram to an application program on another
machine. UDP uses the Internet Protocol to deliver datagrams. Conceptually, the
important difference between UDP and IP is that UDP messages include a protocol
port number, allowing the sender to distinguish among multiple destinations
(application programs) on the remote machine. In practice, UDP also includes a
checksum over the data being sent.
ViewPoint console application. An extensible interactive application for operators,
provided as part of DSM. ViewPoint allows a system or a network to be controlled from
a single terminal. It includes several block-mode display screens for event messages,
a block-mode display for system or network status, a conversational TACL screen, and
a facility called Define Process to maintain sessions with multiple subsystems at the
same time.
wait mode. In the NonStop Kernel operating system, the mode in which the called
procedure waits for the completion of an I/O operation and then returns a condition
code to the caller. Compare nowait mode.
warning. In DSM interfaces, a condition encountered in performing a command or other
operation that can be significant but that does not cause the command or operation to
fail. A warning is less serious than an error. Compare error.
well-known port. Any of a set of protocol port preassigned for specific uses by transport
level protocols (That is, TCP and UDP). Servers follow the well-known port
assignments so clients can locate them. Examples of well-known port numbers include
ports assigned to echo servers, time servers, remote login (TELNET) servers, and file
transfer (FTP) servers.
wild-card character. A character that stands for any possible character(s) in a search string
or in a name applying to multiple objects. In DSM object-name templates, two wild-card
characters can appear: ? for a single character, and * for zero, one, or more
consecutive characters. See also object-name template
.
Xerox Network Services. Early networking protocol suite that is the basis for many
network architectures, including NetWare.
XNS. See Xerox Network Services
.
X.25 Access Method. See X25AM.
X.25 network. Any network or subnetwork linked using X.25 standards. X.25 standards are
CCITT standards that define packet-switching carrier communication in the Network
Layer over wide area networks (WANs). See also packet-switching.
X.25. The CCITT standard protocol for transport level network service. Originally designed
to connect terminals to computers, X.25 provides a reliable stream transmission
service that can support remote logon.