The Trellis system architecture is a client server system, with each document being an engine process that communicated via RPC with interface clients. Each client presents an application-specific view of the information stored an engine.
We have applied Trellis in several domains, including
To get reports on our Trellis projects, access the TAMU HRL server.
Pnet for moderated meeting protocol
referee B objection
browsable CSP program
CSP: three processes shown
CSP program: message sent to East
CSP program: East gets message
CSP program: message sent to X
CSP program: X gets message
Trellis contains mechanisms for expressing the relationships among agents, parallel threads of control, data capture and exchange among agents, hypermedia annotations and documentation, and for analysis of the state space of a process. It is an interpreted system, so processes can change... evolve... as simulation progresses. The colored net formalism on which Trellis is based is also appropriate for expressing CSCW protocols... interactions among the agents involved in a process.
Debit Net, for people processes
We have created Debit Nets, a new class of Petri-net-like automata for representing software processes. In modeling the activities normally undertaken during software development, it is important to allow some actions to proceed even if all its preconditions have not been met. Normal Petri net formalisms do not contains such semantics.
In Debit Nets, some arcs are designated debit arcs, shown with open arrowheads in the diagram. A debit arc indicates that its input place is not required to contain a token for the output transition to be enabled. When a transition fires, if a token is present in the place on a debit arc it will be consumed as normal; if a token is not present, an anti-token (shown as an open circle in the diagram) will be deposited in the place to record a debt. Later, a normal token will be required to combine with this anti-token to pay off the debt.
The current version of Trellis can be obtained from ftp.cs.unc.edu, directory pub/stotts. The system is compiled for SparcStations only, and also requires a Perl interpreter and tcl/tk libraries.