Abstract: An event-driven, multithreaded programmable system permits the network system operator to write concurrently-executing network policies for causing operations to be performed on a computer network in response to changes in state of the computer network. Changes in state are reported to the policy implementation system by monitors interfaced with the network operating system. A policy interpreter scans, screens and parses the network policy statements and builds data structures for managing the multithreaded system in response to state changes supplied by the monitors. The policy interpreter executor issues commands to action engines which in turn cause operations to be performed on the network.

Abstract: This disclosure relates to a system and method for the synchronization of variable-length messages being transmitted between stations of a local area contention network where the messages are made up of a variable number of fixed-length packets. This system is adapted for automatic address assignment of different stations of the network so that the network may be expanded or contracted by adding stations and removing stations respectively. In this manner, a very reliable network is provided in that the failure of any particular station does not interfere with the functioning of the other stations in the network or the network itself. In addition, the system includes provision for associating various server stations with a given procedure so that a client station may broadcast a request for a procedure and corresponding server stations will send the response to the client station containing the network identification of the server station.

Abstract: This disclosure relates to a station for a data transmission network which is adapted to operate in a cyclic mode for contending for access to the network channel along with other stations of the network. The three states of the cycle are the idle state, the packet-being-transmitted state and the acknowlegement period state. Each station will not begin transmission until it determines that the channel is in an idle state. Once the station has determined that the channel is idle, it will then delay for a period of time that is randomly chosen and, if the channel is still idle, will then begin transmission. In this way, contention conflicts between stations is minimized without unduly restricting communication between stations. Following transmission, the channel will again be quiescent a short period of time before the acknowledgement signal is transmitted from the receiver.