Fundamental modeling concepts: Difference between revisions

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=== Compositional Structure Diagram ===

[[Image:FMCBlockDiagram.png|thumb|right|Example of FMC Compositional Structure Diagram]]

Compositional structure diagrams (also known as block diagrams) show the systems structure as a composition of collaborating system components.

:"There are active system components called agents and passive system components called locations. Each agent processes information and thus serves a well-defined purpose. Therefore an agent stores information in storages and communicates via channels or shared storages with other agents. Channels and storages are (virtual) locations where information can be observed." <ref>[http://www.fmc-modeling.org/notation_reference/ fmc-modeling.org Notations Reference]</ref>

Compositional structure diagrams depict the static structure of a system, and the relationships between system components. System components can be active or passive. '''Agents''' are active system components. They perform activities in the system. '''Storages''' and '''channels''' are passive components which store or transmit information.

The image to the right is an example of a compositional structure diagram. It contains the agents ''Order Processor'', ''Supplier Manager'', ''Supplier'', ''Online Shop'' and an unnamed '''human agent'''. Agents are represented by rectangles. The dots and the shadow of the agent ''Supplier'' indicate that this agent has multiple instances, i.e. the ''Supplier Manager'' communicates with one or many suppliers. The so called human agent represents a user interacting with the system.

The diagram contains the storages ''Orders'', ''Purchase Order'' and ''Product Catalog''. Storages are represented by curved shapes. Agents can read from storages, write to storages or modify the content of storages. The directions of the arrows indicate which operation is performed by an agent. In the diagram, the ''Supplier Manager'' can modify the content of the ''Product Catalog'', whereas the ''Order Processor'' can only read the content of the ''Product Catalog''.

Agents communicate via channels. The direction of information flow is either indicated by arrows (not shown in the picture), by a request-response-symbol (e.g. between ''Supplier Manager'' and ''Supplier'') or omitted (e.g. between ''Order Processor'' and ''Supplier Manager'').

=== Dynamic Structure Diagram ===