Distributed systems verification is one of the main issues in software engineering. It is considered as the major field of the formal specification techniques. However, many difficulties remain. In fact, the principal problem is in producing a coherent specification and providing a fully integrated semantics. Since formal methods are mathematical description models that try to give a response concerning the reliability of a system. It remains a hard way for the designers. Thus, we present, in this paper, an open environment for the integration of formal methods in the description and verification of distributed and concurrent systems. The system currently uses UML notation and provides rewriting logic, model checking, theorem proving, and simulation techniques.