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This book does not tell a story. Instead, it is about stories. Or rather, in
technical terms, it is about scenarios. Scenarios of system behavior. It concentrates
on reactive systems, be they software or hardware, or combined
computer-embedded systems, including distributed and real-time systems.
We propose a different way to program such systems, centered on interobject
scenario-based behavior. The book describes a language, two techniques,
and a supporting tool. The language is a rather broad extension of
live sequence charts (LSCs), the original version of which was proposed
in 1998 by W. Damm and the first-listed author of this book. The first of
the two techniques, called play-in, is a convenient way to ‘play in’ scenariobased
behavior directly from the system’s graphical user interface (GUI).
The second technique, play-out, makes it possible to execute, or ‘play out’,
the behavior on the GUI as if it were programmed in a conventional intraobject
state-based fashion. All this is implemented in full in our tool, the
Play-Engine.
The book can be viewed as offering improvements in some of the phases of
known system development life cycles, e.g., requirements capture and analysis,
prototyping, and testing. However, there is a more radical way to view
the book, namely, as proposing an alternative way to program reactivity,
which, being based on inter-object scenarios, is a lot closer to how people
think about systems and their behavior.
We are excited by the apparent potential of this work. However, whether
or not it is adopted and becomes really useful, what kinds of systems are the
ideas most fitting for, and how we should develop methodologies for largescale
applications, all remain to a large extent open questions. Whatever the
case, we hope that the book triggers further research and experimentation. |
