Activity Diagrams in Software Engineering

UML Activity Diagrams

What is UML Diagram…?

UML stands for “Unified Modeling Language”.

It is a industry-standard graphical language for specifying, visualizing, constructing and documenting the artifacts of software system.

The UML uses mostly graphical notation to express the analysis’ and ‘design’ of software projects.

The UML represent a collection of best engineering practices that are very helpful in the modeling o large and complex system.

It is mostly use for simplifies the complex process of software design.

The UML is very important part of developing object oriented software and the software development process.

The UML helps project teams communicate, explore design and validate the architectural design of the software.




  • Class Diagram
  • Component
  • Deployment
  • Object
  • Composite structure
  • Package


  • Activity
  • State Machine
  • Use case


  • Communication
  • sequence
  • Timing


Activity diagrams describe the workflow behavior of a system.

–Activity diagrams are used in process modeling and analysis of during requirements engineering.

–A typical business process which synchronizes several external incoming events can be represented by activity diagrams.

They are most useful for understanding work flow analysis of synchronous behaviors across a process.

  • Activity diagrams are used for

–documenting existing process

–analyzing new Process Concepts

–finding reengineering opportunities.

  • The diagrams describe the state of activities by showing the sequence of activities performed.

–they can show activities that are conditional or parallel.

  • An activity is trigged by one or more events and activity may result in one or more events that may trigger other activity or processes.
  • Events start from start symbol and end with finish marker having activities in between connected by events.
  • The activity diagram represents the decisions, iterations and parallel/random behavior of the processing.

–They capture actions performed.

–They stress on work performed in operations (methods).

When to Use Activity Diagrams  

  • The main reason to use activity diagrams is to model the workflow behind the system being designed.
  • Activity Diagrams are also useful for:

–analyzing a use case by describing what actions need to take place and when they should occur

–describing a complicated sequential algorithm

–modeling applications with parallel processes

  • Activity Diagrams should not take the place of interaction diagrams and state diagrams.
  • Activity diagrams do not give detail about how objects behave or how objects collaborate.


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