Discrete event systems with concurrency are often modelled with
a graphical process modelling technique that generalizes simpler
techniques such as UML activity diagrams and finite state models.
Dozens of tools exist to support systems modelling, simulation, and analysis with Petri nets. Some have found widespread deployment in commercial applications. others are mainly used in the context of university teaching and research.
Petri nets have been studied extensively; they are a common part of the computing science curriculum, and the basis for several process modelling tools, both free and commercial. Many oft-cited examples of Petri nets exist that illustrate a particular modelling technique, provide a construction example or counterexample for a theorem, etcetera.
Petriweb attempts to gather a significant body of such examples into a public repository. The repository can be browsed with a web browser, and individual nets can be retrieved and uploaded in PNML, an emerging standard format supported by many tools.
The repository contains Petri nets with associated properties. Properties are defined by the repository administrator. A property can be defined to be computed automatically from the net's PNML source through an external software program.
Browsing and use of the nets in the repository is open to all; to upload nets, you must register as a user. Uploaded nets can only be viewed by the uploading user and the administrator, until the latter approves them.
Petriweb is still in the prototype phase. It supports a restricted form of PNML, including flat, uncoloured nets, plus limited support for hierarchy. The database only contains a handful of examples. You are most welcome to register, and upload your own.