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differenc
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PART 1: What is Activity
Diagram
3. Activity diagram illustrate 3 flow methods, as follows:
Parallel
Branched
Concurrent
1. Activity diagram describe the dynamic aspects of the system. Activity
diagram is basically a kind of flowchart to represent the flow from one
activity to another activity, but not a flowchart.
2. A kind of flow chart to represent the flow of one activity to another
activity but not a flowchart
• This means that two tasks can literally run at same time
• This means having a task and that task is been evaluated in another
task A or task B
• This means when two or more task can start, run, and complete in
overlapping time period.
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Purpose of Activity Diagrams
1. Activity is a particular operation of the system. Activity diagrams
are not only used for visualizing the dynamic nature of a system,
but they are also used to construct the executable system by using
forward and reverse engineering techniques. The only missing thing
in the activity diagram is the message part.
2. The purpose of an activity diagram can be described as −
• 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.
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PART 2: How to Draw an Activity Diagram?
1. Before drawing an activity diagram,
we must
have a clear understanding about the
elements
(notations) used in activity diagram.
1. Notations
• Initial state start point
A small filled circle with an arrow.
It defines the initial state or start point for
any activity diagram
• Activity or action state
An action state represents the non-interruptible action
of objects. You can draw an action state in SmartDraw
using a rectangle with rounded corners.
Activity
• Action flow Action flows, also called edges and paths, illustrate the transitions
from one action state to another. They are usually drawn with
an arrowed line.
Before drawing an activity diagram, we should
identify the following elements:
• Activities . Association
• Conditions, and Constraints
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How to Draw an Activity Diagram?
• Object flow
Object flow refers to the creation and modification of objects
by activities. An object flow arrow from an object to an action
indicates that the action state uses the object.
Activity
Class/object
• 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
• Guards
.
In UML, guards are a statement written next to a
decision diamond that must be true before moving
next to the next activity. These are not essential, but
are useful when a specific answer, such as "Yes,
three labels are printed," is needed before moving
forward
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How to Draw an Activity Diagram?
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.
Time Event
This refers to an event that stops
the flow for a time; an hourglass
depicts it.
Merge Event
A merge event brings together
multiple
flows that are not concurrent.
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How to Draw an Activity Diagram?
Sent and Received
Signals Signals represent how activities can be modified from
outside the system. They usually appear in pairs of sent
and received signals. For example, an authorization of
payment is needed before an order can be completed.
Interrupting
Edge
An event, such as a cancellation, that interrupts
the flow denoted with a lightning bolt.
Swimlanes group related activities into one column.
Swimlanes
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How to Draw an Activity Diagram?
3. Following is an example of an activity diagram for order
management system. In the diagram, four activities are identified
which are associated with conditions. One important point should be
clearly understood that an activity diagram cannot be exactly matched
with the code.
Following diagram is drawn with the four main
activities
• Submit student details.
• Check attendance and yearly income.
• Approve or decline.
Final State or End
Point An arrow pointing to a filled circle nested inside
Another circle represents the final action state.
Interrupting
Edge
An event, such as a cancellation, that interrupts
the flow denoted with a lightning bolt.
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Where to Use Activity Diagrams?
1. Activity diagram is suitable for modeling the activity flow of the
system. An application can have multiple systems. Activity
diagram also captures these systems and describes the flow
from one system to another. This specific usage is not available
in other diagrams. These systems can be database, external
queues, or any other system.
2. This diagram is used to model the activities which are nothing
but business requirements. The diagram has more impact on
business understanding rather than on implementation details.
Activity diagram can be used for:
• Modeling work flow by using activities.
• Modeling business requirements.
• High level understanding of the system's
functionalities.
• Investigating business requirements at a later
stage.
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Uml behavior
diagram that
represents the work
flow of stepwise
activity of the
system
Activity diagram vs Flowchart diagrams?
Activity Diagram Flowchart Diagrams
Graphical diagram that
represents the
sequence of steps
Includes parallel flow,
merge, fork, swimlane
etc.
Does not contain
advanced concept as of
activity diagram
Part of Uml diagram
suite.
Not a Uml diagram.
Part 3:
