Activity chart

Activity chart
See also

Activity chart is a graphical description of activities and actions used to illustrate workflows. Workflow is a work sequence process. This is a specific position of a state diagram in which mostly or all of the elements have an activity effect (or subactivity) and in which mostly or all of the proceedings are caused by end of the activities or subactivities. The main function is to concentrate on flows pushed by interior processing (UML Revision Task Force s. 299). It describes actions between many objects between which communication occurs during the performance of activities. The activity chart is also used to create how the set of use cases integrates to present business workflows. Using an activity chart, without knowing the domestic information ( they are demanded by collaboration diagram), is really useful to understand the first-class execution attitude of structure (G. Booch i in. 1999, s. 31). Through the activity chart, we can visualize the activities performed by a worker and one (or more) devices at the same time (International Labour Office 1992, s. 123). We can use activity diagrams when all or most of the events end internally ("that is, the procedural flow of control"). Normal diagrams (state diagrams) are used for asynchronous operations (UML Revision Task Force s. 299).

Elements of Activity Chart

The activity chart contains activities and transitions to display the flow of control from one action to another. It “has a start and end nodes” (T. Janowski, M. Hrushikesha 2010, s. 258). There are five key elements in the diagram (Activity, Decision, Synchronization Bars, Transition and Swim Lines). Building a chart, we don't have to use all of these parts. However, using all parts we create a productive scheme. In fact, there are also many diagrams consisting only of Transitions and Activities (Daniel R. Windle, L. Rene Abreo 2003, s. 58). The activity chart consists of a certain number of window form, that are connected together by arrows. Below are the most commonly used and most important window shapes (OMG Unified Modeling Language Superstructure Specification, s. 414-415) :

  • Initial state - a black dot, used as starting point;
  • Action - ellipse/rectangle with rounded corners, it concerns the performance of an action;
  • Arrows - indicate the order of performing the action;
  • Control Flow - two ellipses connected by arrow, it shows the page where the information flows;
  • Decision - rhombus or diamond, gives you the opportunity to choose;
  • Start or Ened Synchronal Activities - "black bars, show the activities carried out at the same time";
  • Flow Final - a circle with an "x" in the middle, is a control final node that ends a flow;
  • Fork - resembles a fork made of arrows, holds up synchronous activities;
  • Swimming lanes - broken solid lines show which element is currently performing the action;
  • The End - a black circle surrounded by a second circle.


Author: Sandra Kaczara