1 Enhancing Collaborative Synchronous UML Modelling with Fine-grained Versioning of Software Artefacts A. De Lucia*, F. Fasano*, G. Scanniello † , G. Tortora* adelucia@unisa.it, ffasano@unisa.it, gscanniello@unisa.it, tortora@unisa.it * Dipartimento di Matematica e Informatica - Università di Salerno Via Ponte don Melillo - 84084 Fisciano (SA) - Italy † Dipartimento di Matematica e Informatica - Università della Basilicata Viale dell’Ateneo, 10 – Macchia Romana – 85100 – Potenza - Italy Abstract Software development teams are composed of people with different knowledge and skills, who contribute to a project from often widely dispersed locations. Software development in geographically distributed environments creates software engineering challenges due to the interaction among members of distributed teams and the management of consistency and concurrency among project artefacts. In this paper we propose STEVE (Synchronous collaborative modelling Tool Enhanced with VErsioning management) a collaborative tool supporting distributed UML modelling of software systems. The tool provides a communication infrastructure enabling the concurrent editing of the same UML diagram at the same time by distributed developers. Complex UML diagrams are decomposed and managed in a fine-grained hierarchy of sub-artefacts, thus providing change and configuration management functionalities for both the diagram and the graphical objects. Thus, software predefined diagram components can be consistently reused and shared across different diagrams of a given project. 1. Introduction The phases of a process development model typically involve the interaction of specialists in different geographical settings and from different fields, who must communicate their decisions and coordinate their activities. Therefore, software organisations require new paradigms and tools to reduce development costs,