Abstract: An architecture model is provided in this paper. Consistencies required to be preserved in the architecture evolution are also discussed. A rulebased approach of architecture evolution is introduced. With communicating sequential processes as the formalization approach, condition as preserving consistencies is defined in behavior and structure evolution of architectu re at abstract layer. Formalization restriction of every rule is so defined that the condition of consistencies is still right at the end of evolution.

Key words: architecture evolution, consistency, communicating s equential processes