Activity diagrams visually represent the flow of control and actions in a system, serving as a tool for business process modeling. Key components include initial states, actions, decisions, synchronization, and final states, which help delineate the sequence and structure of activities. These diagrams are useful for modeling workflows, business requirements, and understanding system functionalities.

1. Software Requirement
Activity Diagram Model

2.  An activity diagram visually presents a series of actions or flow
of control in a system similar to a flowshart or a data
flow diagram. Activity diagrams are often used in business
process modeling.
 Contrary to use case diagrams, in activity diagrams it is
obvious whether actors can perform business use cases
together or independently from one another
Overview

3. Purpose:
Draw the activity flow of a system.
Describe the sequence from one activity to
another.
Describe the parallel, branched and
concurrent flow of the system.

4. How to draw Activity Diagram?
before drawing an activity diagram we should identify
the following elements:
 Initial State or Start Point
 Activity or Action State
 Object Flow
 Decisions and Branching
 Synchronization
 Time Event
 Final State or End Point

5. Initial State or Start Point
A small filled circle followed by an arrow represents
the initial action state or the start point for any
activity diagram.

6. Activity or Action State
 An action state represents the non-interruptible action of
objects.

7. Action Flow
Action flows, also called edges and paths,
illustrate the transitions from one action state
to another

8. Decisions and Branching
A diamond represents a decision with alternate
paths. When an activity requires a decision prior to
moving on to the next activity, add a diamond
between the two activities.

9. Synchronization
A fork node is used to split a single incoming
flow into multiple concurrent flows. It is
represented as a straight, slightly thicker line
in an activity diagram.
A join node joins multiple concurrent flows
back into a single outgoing flow.
A fork and join mode used together are
often referred to as synchronization.

11. Time Event
 This refers to an event that stops the flow for a time; an hourglass depicts it.


12. Merge Event
 A merge event brings together multiple flows that are not concurrent.

13. Accepting an Event (Action)
 This action waits for an event to occur. After the event is accepted, the flow that
comes from this action (and is defined in the activity diagram) is executed.
Accepting events is an important element for business processes in activity
diagrams:

14. Sending Signals (Action)
 Sending a signal means that a signal is being sent to an accepting activity:


15. Final State or End Point
1.
 An arrow pointing to a filled circle nested inside another circle represents the final
action state.


16. Activity Partition
User do action and system reply

17. EX:

18. Where to use Activity Diagrams?
Modeling work flow by using activities.
Modeling business requirements.(usecase
scenario)
High level understanding of the system's
functionalities.
Investigate business requirements at a later
stage.