ExSpecT

ExSpecT (Executable Specification Tool) is a process modelling toolbased on high level Petri nets.

ExSpecT models

An ExSpecT model is a hierarchical, coloured Petri net: it consists of transitions and places, connected by arcs; the structure of these nets is displayed as a set of diagrams.

A transition represents a subprocess; there are two kinds:;processor: primitive, contains processing logic;system: contains another Petri net

A place represents state information: there are two kinds:;channel: represents control flow: contain data items called "tokens" that processors can consume and produce;store: represents collective data: processors can read, write and modify them

The values of tokens and stores are strongly typed. Transitions contain processing logic, written in a functional language, that describes the relationships between the values of the tokens they consume and produce and the stores they access.

ExSpecT tool features

The ExSpecT editor supports direct manipulation of diagrams to create the control flow structure, and forms-based specification of data types and values and processing logic.

The ExSpecT simulator supports simulated execution of processes, both stepwise and completely automated (randomized). The state of the process is visualized in the diagram.

The "dashboard" feature allows user interface elements to be associated with the system; during simulation these elements display the (structured) values passing the system at that point, or prompt the user to specify such values.

In this way, fully functional prototypes of systems, including the user interface, can be developed directly from their specifications.

ExSpecT implementations

ExSpecT was developed in the early 1990s by a research group led by Kees van Hee at TU Eindhoven. The first versions ran on SunOS 4 operating system with the SunView windowing system. Later versions used the XView window toolkit. A port was done to Solaris 2.

From 1995, a Microsoft Windows version of the user interface was developed using the XVT windowing toolkit by Bakkenist, a consultancy firm, and a COM server interface to the simulator was added. In the latter form the simulator is part of the Protos process modeling tool.

ExSpecT today

Today, ExSpecT is used in education and research, and finds some commercial use; the software is kept alive, but is not under active development.

ExSpecT can be freely downloaded and used, but the source code is not public.

ExSpecT webpage

* [http://www.exspect.com/ ]