Sequence Diagrams for Mobility.

There are several kinds of UML diagrams for convenient modelling of behaviour, but these diagrams can be hardly used for modelling mobility. The situation is not very different in the case of agent languages. There exist already some proposals for modelling mobility of interacting agents by graphical notations, but these notations are rather not very intuitive and hard to read if the specification becomes a bit complex. In this paper we propose a new graphical notation for modelling interaction of mobile objects. The notation is based on UML sequence diagrams. We model behaviour of mobile objects using a generalized version of lifelines. For different kinds of actions like creating, entering or leaving a mobile object we use stereotyped messages. We provide also a zoom-out, zoom-in facility allowing us to abstract from specification details. We explain our notation in a series of examples; study its applicability and limits.