The Activity Diagram. Modelling workflows.
What are activity diagrams, why are they important and what benefits do they provide?
Activity diagrams depict the activities in a system that are made up of a series of actions.
An initial node represents the beginning of the process.
A fork or splitting node allows parallel functions to be represented. “Parallel” in this sense refers to events that happen separate from each other though not necessarily simultaneously.
Confirm by user is an action, or a step in an activity, in which a user or system carries out a function.
Parallel processes can be reunited using the join node. After the reunification all control tokens and identical object tokens are melded together.
Decision nodes visualize alternative workflows and are depicted using a # sign. Generally alternative workflows are connected to conditions.
A conflation purifies flows that are divided at a decision node.
The end node displays the end of an activity. When an end node reaches the end, the activity also ends.
What is an Activity Diagram?
An activity diagram shows business and software processes as a progression of actions. These actions can be carried out by people, software components or computers. Activity diagrams are used to describe business processes and use cases as well as to document the implementation of system processes.
Even the most complex progressions can be visualized by activity diagrams. Sequential and peripheral workflows are depicted by control and object flows. Activity diagrams represent activities that are made up by a flow of actions.
What are Activity Diagrams Used for?
Activity diagrams area ideal for describing the following processes:
- Use cases and the steps described in them,
- Business processes or workflows among users and systems,
- Software protocol, i.e. the permissible sequence of interactions between components
- Software algorithms
Activity diagrams can be divided into a few areas of responsibility such that these actions can be assigned to particular model elements like classes or components.
Why are Activity Diagrams Important?
Activity diagrams can be used in many different situations. In addition, various relationships between activity diagrams and other UML diagrams can exist. Activity diagrams are well suited to visualizing models of procedures and their management. Activity diagrams illustrate the individual steps in activities as well as the order in which they are presented. They can be used for a range of functions: from the modelling of business processes all the way through to the depiction of control flows. Activity diagrams can be used anywhere where behavior needs to be described or where control flows need to be modelled.