Smart play-out

We describe "smart play-out", a new method for executing and analyzing scenario based behavior, which is part of the Play-In/Play-Out methodology and the Play-Engine tool. Behavior is "played in" directly from the system's GUI, and as this is being done the Play-Engine continuously constructs Live Sequence Charts (LSCs), a powerful extension of sequence diagrams. Later, behavior can be "played out" freely from the GUI, and the tool executes the LSCs directly, thus driving the system's behavior. An inherent difficulty in constructing a "play-out" mechanism is how to resolve the nondeterminism allowed by the LSC specification in order to obtain an executable model. Smart playout, is a recent strengthening of the play-out mechanism, which addresses this problem by using powerful verification methods, mainly model-checking, to execute and analyze the LSCs, helping the execution to avoid deadlocks and violations. Thus, smart play-out utilizes verification techniques to run programs, rather than to verify a program with respect to given requirements, as in traditional verification approaches. The ideas appear to be relevant in various stages of system development, including requirements specification and analysis, implementation and testing.