Shape Reference - Overview

Block Diagram

A Block diagram describes the compositional structure of a system as a composition of collaborating system components. A Block diagram consist of active components, called Agents, that perform operations visible on passive components, called Locations, which save the information processed by the agents. Locations are divided into two categories namely Storages and Channels. Agents may store information to Storages and transmit information to other agents via Channels.

Petri Net

A Petri Net is a directed graph describing causal dependencies between events, operations, and activities and thus defining a process type. Transitions descibe the events, operations, and activities whereas the causal dependencies between them are described by the marking of the places. Petri nets are used to describe the behavior, the dynamic structure, of a system and of agents.

E/R Diagram

E/R diagrams are bipartite graphs used to describe value range structures or topic diagrams. Value range structures describe observable values at locations within the system whereas topic diagrams allow a much wider usage in order to cover all correlations between interesting points. The main elements of an ER diagram are entity sets and relations among them.

Layer Diagram

Layer diagrams are used to illustrate layerings, i.e. quadratic relations. Elements of a set thus appear in two different, hierarchically distinct, roles in the relation. Thus an ordering criterion exists, so that an element can be ordered as a junior of another element. E.g. if a set consists of routines in a computer program and the relation is "A calls B", routines can assume the role of the caller or the callee.

Shared Masters

This is no diagram type but Shared Masters are a common part of all stencils and are therefore described only once within this Help.