to the English edition Many processes that describe the operation of
engineering, economic, organiza- tional, and other systems are
represented as sequences of operations performed on material,
information, or other types of flows. Typical examples are processes of
connection of telephone users, data transmission and processing,
calculation at multi user computer centers, and queueing at service
centers. The models studied by the theory of service systems, or
queueing theory, are used to describe such processes. The more
pessimistic term "queueing theory" is used more often in the non-Soviet
literature. Random arrivals (requests for service), probability
distributions defining queueing processes (distributions of service
times and acceptable waiting times), and structure parameters (customer
priorities, parameters that delimit acceptable queues, parameters that
define paths of customers, etc.) are characteristic com- ponents of
queueing models. Typical output characteristics of queueing models are
the probability distributions of queue lengths, waiting times, lengths
of busy periods, and so forth.