Specifications and description language (SDL)

Initial SDL recommendations were produced by CCITT in 1976. Recent versions are SDL-88 and SDL-92. SDL explains a path for gradual conversion from informal specification to formal specification. SDL also supports designing of web, high-level programming and simulation. SDL also supports both graphical representation and textual representation (phrase representation). In this model, we have a collection of EFSMs. They communicate with one another. A start node is related to state machine while starting. Then transitions describe the behaviour of the system.

QoS processing

Here processing is performed by a software system that will attend the user, application and transmission perspectives. In the parlance of current agent-based software systems, software which is capable of handling even user requests is termed as User-QoS-Agent or UQA. The three top layers in the QoS processing model are the user perspective layer (UPL), the application perspective layer (APL) and the transmission perspective layer (TPL). The three distinct steps in QoS processing are assessment, mapping and negotiating.

Networking devices

A multimedia network connects a large number of networking devices like computers, servers, terminals, printers, workstations, scanners, plotters, cameras etc. In the initial stage, in batch processing systems, users usually submit their tasks to a computer operator on punched tape or punched cards and subsequently operator perform these tasks. A terminal network uses a single mainframe computer that connects many user terminals. Here we use star topology. Every user terminal is connected to an RS-232 port. The I/O devices are known as console, terminal and workstation. Teletype (TTY), a mechanical device is an I/O device used as a console. CRT based terminals are also known as dumb terminals, smart terminals and intelligent terminals. User communicates to a remote computer in the terminal emulation mode. Terminals with advanced features are called workstations. The front-end processor (FEP) is a device which makes the host processor easy to transmit input and output data to the user terminals. A concentrator is a device which is often used to mix the traffic of a large number of terminals which are relatively low speed terminals and after combining concentrator allows passage towards FEP through an ultrahigh speed port.