A declarative language for data and telex exchange configuration

The LEP language is a simple, declarative language designed to define the routing and customizing rules of a telex exchange, but the concepts employed can easily be applied to telephony or data transmission. The language is in accordance with CCITT Series Z.300 Recommendations. The user writes a LEP text using a text editor-possibly in the exchange console-and then follows the normal procedures: compilation, simulation of the configuration programmed, and installation of the latter in the exchange on a resident basis. The compilation programs perform the static error detection tasks and generate the necessary tables. They also supply auxiliary information which help with the simulation and corection of errors involving logical inconsistencies. The paper discusses the general abstraction used in this language based on the present packet switching experience