Abstract: The importance of early performance assessment grows as software systems increase in terms of size, logical distribution and interaction complexity. Lack of time from the side of software developers, as well as distance among software model notations and performance model representation do not help to build an integrated software process that takes into account, from the early phases of the lifecycle, non functional requirements. In this paper we work towards filling this gap by extending the capabilities of a simulative environment developed for the UML notation. Out intent is to introduce new stereotypes representing performance related items, such as resource types and job dispatchers. They allow the software designers to homogeneously represent a software architecture integrated with a running platform as well as parameterized with the resource demand that the components require.