The Metamodel



As safety cases evolve to cover the whole of the life cycle, changes will be a frequent occurrence. This presents a significant challenge to System Engineers and the DSM meta-model has been designed to address these challenges.  Within the DSM metamodel, these entity types have been defined:

     General: Package, query, report, matrix

     GSN: Goal, Strategy, Assumption, Justification, Solution,        Evidence, Context Arrow, Support Arrow, GSN Diagram

     Causality: Causal Diagram, State, Simple Event, Mishap Event, Event Logic, Guard Arrow, Component,        Component instance, Trigger Arrow, Sequence Arrow, Causal diagram

     Bowtie: Bowtie Event, Threat Line, Control, Control Event, Event, Hazard, Hazard Arrow

Each entity is a single source of truth and remains the same in whichever diagram it is used.  Thus if the entity is changed, the change will be reflected in all the diagrams.

Both boxes and arrows are entities, and all entities can be extended with data fields and new relationships. For instance, GSN goals could be associated with their main diagram.