Activity (software Engineering)

Activity diagrams

are graphical representations of workflows of stepwise activities and actions
with support for choice, iteration, and concurrency.
In the Unified Modeling Language, activity diagrams are intended to model both computational and organizational processes (i.e., workflows), as well as the data flows intersecting with the related activities.
"Object nodes hold data that is input to and output from executable nodes, and moves across object flow edges.
Control nodes specify sequencing of executable nodes via control flow edges."
In other words, although activity diagrams primarily show the overall control flow, they can also include elements showing the data flow between activities through one or more data stores.

Construction

Activity diagrams are constructed from a limited number of shapes, connected with arrows. The most important shape types are as follows:
* '' stadia'' represent ''actions'';
* ''diamonds'' represent ''decisions'';
* ''bars'' represent the start (''split'') or end (''join'') of concurrent activities;
* a ''black circle'' represents the start (''initial node'') of the workflow;
* an ''encircled black circle'' represents the end (''final node'').
Arrows run from the start towards the end and represent the order in which activities happen.

Activity diagrams can be regarded as a form of a structured flowchart combined with a traditional data flow diagram. Typical flowchart techniques lack constructs for expressing concurrency. However, the join and split symbols in activity diagrams only resolve this for simple cases. The meaning of the model is not clear when these symbols are arbitrarily combined with decisions or loops.

While in UML 1.x, activity diagrams were a specialized form of state diagram, in UML 2.x, the activity diagrams were reformalized to be based on Petri net-like semantics, increasing the scope of situations that can be modeled using activity diagrams. These changes cause many UML 1.x activity diagrams to be interpreted differently in UML 2.x.

UML activity diagrams in version 2.x can be used in various domains, e.g. in design of embedded systems. It is possible to verify such a specification using model checking techniques.I. Grobelna, M. Grobelny, M. Adamski, "Model Checking of UML Activity Diagrams in Logic Controllers Design", Proceedings of the Ninth International Conference on Dependability and Complex Systems DepCoS-RELCOMEX, Advances in Intelligent Systems and Computing Volume 286, Springer International Publishing Switzerland, pp. 233-242, 2014

See also

* Specification and Description Language
* Business Process Modeling Notation
* Control-flow graph
* Data flow diagram
* Drakon-chart
* Event-driven process chain
* List of UML tools
* Pseudocode
* State diagram
*Flowchart
*Activity cycle diagram

References

External links

Articles on UML 2 Activities and Actions

{{DEFAULTSORT:Activity Diagram
Unified Modeling Language diagrams
Systems Modeling Language
Modeling languages

es:Diagrama de actividades