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Here, we are going to discuss about Activity diagram used by business analysts.
An Activity Diagram are one of the diagram the UML for Modelling in the Dynamic Aspects the system.
An Activity Diagram is Drawn to model how the system should function in order to achieve Business Logic, Business Functionality and Business Objectives.
An Activity Diagrams is a flow chart showing flow of control from activity to activity which says about what is happening
in the system through System Perspective but not in actor
perspective.
Activity Diagrams are used for the modelling the logic captured
by a single use case or for the detailed logic of a business rule.
Activity diagram are object-oriented equivalent of flow charts, process flow diagram, data flow diagrams from structured development.
These diagrams shows flow of control based on sequence and conditions of the flow. It is drawn from one operation to another
and it is not only used for visualizing Dynamic nature of the system but they are used to construct the executable system by
using forward and reverse engineering techniques.
Differences Between Flow Chart and Activity Diagram:-
| Flow Chart | Activity Diagram |
| 1. Customer visits the ATM machine.
2. Customer enters the details Of the card details and Password. 3.Customer enters the amount details and withdraws the amount 4. Customer checks the amount and leaves the ATM Machine. |
1. System accepts the card details and password.
2.System verify the details and process to the Amount Withdraws. 3.System Checks the Withdrawal amount details and Process the amount through machine. 4.System Updated the details of the customer. |
Drawing Elements are used to control the operations in the activity diagram and following are the basic components in the
activity diagram.
Basic Components or Drawing Elements in Activity Diagram:
| SL.NO | Symbol | Name | Description |
|
1.
|
 |
Initial Node Start Node |
It Indicates Work Flow Begins |
|
2. |
 |
Control Flow |
It Shows the direction of work flow. An Horizontal Arrow indicates it flows from left to right.
An vertical arrow indicates flow from top to bottom. |
|
3. |
 |
Final Node End Node |
It is the final node representing the last step in the activity. |
|
4. |
 |
Stop Node |
It indicates the Exit from the flow. |
|
5. |
 |
Activity |
It indicates a Step in a process.
It is unit of work done by the system or it is state achieved consistent. |
|
6. |
|
Decision Box |
It indicates the work flow from one path to number of possible paths based on the guard conditions,
It is also Shown as 1:m |
|
7.
|
|
Connector
|
It also used as connector which as multiple inputs and multiple outputs. It also shown as m:n or n:m.
|
| 8.
|
 |
Branch and merge |
It is used to combine multiple concurrent activities and reintroduce them to a flow where only one activity occurs at a time. It is represented by thick vertical or horizontal line.
|
|
9. |
 |
Fork and Joint |
Splits a single activity flow into multiple concurrent activities and it is symbolized with multiple arrowed lines from a joint |
|
10. |
 |
Nested Loop Activity | It is an activity may contain a series of activities internally |
|
11. |
Continution Node | It indicates continuity from one page to another page and it is also used for reusable of code. | |
|
12. |
Guard Condition | It is attached to control flow when the condition is true. It also flows
Along the workflow and it is represented by a square brackets.
|
|
|
13.
|
Event | Event is external triggered (or) it is
Consistent point of a specified timeframe. It is indicated without square brackets. |
How to draw Activity Diagram?:
An Activity Diagram must have a clear understanding about elements used in activity diagram. The main element of activity diagram is activity itself. We should identify the following elements:
- Activity
- Conditions
- Events
Activity Diagram are not only important for modeling the dynamic aspects of a system, but also for constructing executable systems through forward and reverse engineering.
Notes:-
1.Activity Diagrams are drawn to simplify Complexity.
2.Activity Diagrams can be drawn at any level.
3.Activity Diagrams can be drawn based on frequency.
4.Multiple activity diagrams can be drawn for a single case study but there will be only one Use case diagram.
5.If we are drawing a multiple activity diagram then we should have headings based on points 2 and 3.
- Below is the sample diagrammatic representation of the Activity Diagram and points to be noted:-
- Few things that you need to keep in mind while developing this diagram are as follows:
1)Restrict your description to the functionalities of the system while developing it so that outsiders wont misuse it.
2)Make sure conditions involves all kinds of possibities; otherwise involve ‘else’ if you are not sure.
3)In case of fork and join, make sure that there are equal number of flows that leave and end at fork and join respectively.
