A discrete-time UML semantics for concurrency and communication in safety-critical applications

Abstract

We define a subset krtUML of UML which is rich enough to express such modelling entities of UML, used in real-time applications, as active objects, dynamic object creation and destruction, dynamically changing communication topologies, combinations of synchronous and asynchronous communication, and shared memory usage through object attributes. We define a formal interleaving semantics for this kernel language by associating with each model M ∈ krtUML a symbolic transition system STS(M). We briefly outline how to compile models of industrial systems making use of generalisation hierarchies, weak and strong aggregation, and hierarchical state-machines into krtUML. The main aim of the paper is to provide an executable semantics for krtUML suitable for the formal verification of temporal model properties with existing model-checking tools.

An Approach for Synthesizing Intelligible State Machine Models from Choreography Using Petri Nets

“…They have been developed based on [14], [15], and reported in [13]. A state machine has a message pool and its state is defined by a consistent set of active states, set of suspended regions, set of messages in the message pool, and values of the attributes.…”

Supporting UML-based development of embedded systems by formal techniques

“…A discrete time semantics [9] has been implemented, where only the order between the observable entities is considered. A discrete time step corresponds to the execution of a transition in a state machine or the removal of an event from an event queue.…”

“…Within OMEGA, this led to extensive discussions and decisions on semantic variation points and unclear issues in the definition of UML. Our starting point was an operational semantics [10,9] which was especially inspired by the execution mechanism of Rhapsody. Whereas many formal methods require flat state machines, this semantics also includes hierarchy and orthogonality which is convenient for modeling.…”

“…For instance, we abstracted from the pending request table for operation calls in [9] and used explicit synchronization between caller and callee. Moreover, the semantics has been defined in an incremental way, starting from a basic non-timed semantics.…”

Direct Semantics of Extended State Machines.

“…Many approaches to defining the semantics of UML state machines use flattening to reduce a state machine with composite states and features such as history states to simple finite state machines in which there are only non-composite states and simple (single source, single target) transitions without pseudostates [6,19]. The problem with this approach is that the structure of the original model will be lost and the number of states and transitions to be considered increase significantly.…”