Activity Diagram | Scenario and Case Study Base Project Examples
Activity diagrams are behavioral diagrams.

Activity VS Task
An activity is work that is done with no specific purpose in mind or in some cases, activity can have a mini purpose.
The task is a big term as compared to activity and task is specifically an activity that is done with only having a particular purpose in mind.
What is Activity?
A project is divided into many interdependent activities to complete a task.
The sequence or the order of the activities is very important.

Activity Diagram Case Study 1
Suppose we want to develop a web-based social network with the following functionalities;
The user should signup for the system.
The user should log into the system and can send friend requests or block the user.
Solution:
We need to convert this system into separate components;
Activity 1: Sign up
Activity 2: log in
Activity 3: Send Friend request
Activity 4: block a user
Explicit requirements VS implicit requirements
Explicit requirements:
- Understood
- Clearly described by the customers
implicit requirements:
- Not Understood
- Not Clearly described r by the customers
Explicit requirements |
implicit requirements |
Sign up | Show form and enter data |
log in | Email confirmation |
Send Friend request | Show message of success |
Accept friend request | Search a user |
Block user | View profile |
Activity Diagram for module 1 of case study 1

Activity Diagram for module 2 of case study 1

Activity Diagram for module 1 of case study 2
The user can search books, viewbooks Without any fee but can download the Book only and only if he pays money. Provide the facility of managing the cart To the user, so that he can update his cart.

How many activity diagrams for 1 Project?
In most of the cases;
- 1 activity diagram for each separate module of your project.
- The activity of one module can also be drawn in another module if required.
- Don’t mix all activities of all modules of your big project in only one diagram.
- 1 diagram represents the flow of one selected activity from starting to end. Only helping activities can be drawn with the selected activity.
Purpose of Activity Diagram
- Draw the activity flow for a system
- Describe the sequence from one activity to another
- High-level understanding of the system’s functionalities
- Modeling business requirements
- Investigating business requirements as and when required