Activity (UML)

An activity in Unified Modeling Language (UML) is a major task that must take place in order to fulfill an operation contract.

The Student Guide to Object-Oriented Development defines an activity as a "sequence of activities that make up a process.

[2] An activity can represent: Activities can be decomposed into subactivities, until at the bottom we find atomic actions.

In UML 2.0 an activity is no longer based on the state-chart rather it is based on a Petri net like coordination mechanism.

There the activity represents user-defined behavior coordinating actions.