Rules of modeling

There are a number of important rules that must always be followed when modeling workflows:

• Each workflow must have precisely one Start status.
• Each workflow must have at least one End status.
• The “Start” status can follow precisely one outgoing transition.
• An “End” status is not allowed to have any outgoing transitions.
• Transitions represent a target-oriented connection between precisely one source and one target element.
• A transition's source and target element can only take the form of a status and an activity, but not other transitions.
• Statuses and activities can have as many incoming and outgoing transitions as desired (exceptions: “Start” and “End”).
• Transitions can only ever run between one status and one activity, never between two statuses or two activities.
• The status and activity elements must always have reference names that are unique (to the workflow).
• Transitions are allowed to have a name; this name must be unique in relation to the associated starting element. If a transition does not have a name, the names of the subsequent status and subsequent activity are used (preceded by a triangle).

Examples for the modeling rules

Modeling rule for status and activities

A “status” is always followed by an “activity”. The status and activity are connected by means of “transitions” and have to have a unique reference name. Names can be assigned to transitions and each of these must be unique in relation to the respective starting element.

Modeling rule for one status and multiple activities

A status can be followed by multiple activities. Likewise, multiple activities can lead to one status.

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One activity can lead to multiple statuses. Likewise, multiple statuses can trigger one activity.

A script can only be attached to an (automatic) activity and the connecting line does not run in a specific direction.