TERMOS: a Formal Language for Scenarios in Mobile Computing Systems Hélène Waeselynck 1,2 , Zoltán Micskei 3 , Nicolas Rivière 1,2 , Áron Hamvas 3 , Irina Nitu 1,2 1 CNRS; LAAS 7 av. Colonel Roche F-31077 Toulouse, France 2 Université de Toulouse UPS, INSA, INP, ISAE ; LAAS F-31077 Toulouse, France 3 Budapest University of Technology and Economics Muegyetem rkp. 3 1111 Budapest, Hungary {waeselyn, nriviere}@laas.fr, micskeiz@mit.bme.hu Abstract. This paper presents TERMOS, a UML-based formal language for specifying scenarios in mobile computing systems. TERMOS scenarios are used for the verification of test traces. They capture key properties to be checked on the traces, considering both the spatial configuration of nodes and their communication. We give an overview of the TERMOS design and semantics. As part of the semantics, we present the principle of an algorithm that computes the orders of events from a scenario. Two proof-of-concept prototypes have been developed to study the realization of the algorithm. Keywords: Mobile computing systems, UML Sequence Diagrams, formal semantics, testing. 1 Introduction Graphical scenario languages (e.g., Message Sequence Charts [1], UML Sequence Diagrams [2]) allow the visual representation of interactions in distributed systems. Typical use cases, forbidden behaviors, test cases and many more aspects can be depicted. The popularity of graphical scenarios is due to their user-friendly syntax, which facilitates communication while opening the door for formal treatments (this however requires that the used notation has a precise semantics). We investigate one of such formal treatments, namely the automated analysis of test traces. In our work, a scenario captures a key property to be checked on the traces. Scenario-based verification is not a novel approach, the originality here is that we apply it to a specific class of distributed systems: mobile computing systems. Mobile computing systems involve devices (handset, PDA, laptop, intelligent car) that move within some physical areas, while being connected to networks by means of wireless links (Blue-tooth, IEEE 802.11, GPRS). Such systems differ from “traditional” distributed systems in many aspects: frequent connections and disconnections of mobile nodes, communication with unknown partners in a local