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Software Design
Lecture : 22
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Categories of UML Diagrams (3)
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Static
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Use case diagram
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Class diagram
Dynamic
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Activity diagram
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Implementation
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Component diagram
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Deployment diagram
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Introduction to Activity Diagram
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In many ways UML Activity diagrams are the object
oriented equivalent of flow charts and dataflow
diagrams (DFDs). They are used to explore the logic of:
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A complex operation
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A complex business rule
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A single use case
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Several use cases
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A business process
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Activity Diagram – Dynamic
Category
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It shows the flow from activity to activity within
a single process ie Work Flow.
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With an activity diagram, you can also model the
flow of an object as it moves from state to state
at different points in the flow of control
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Basic Vocabulary of Activity
Diagram
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Diagrams are read from top to bottom and have
branches and forks to describe conditions and
parallel activities
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Initial State
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filled in circle is the starting point of the
diagram. An initial node isn’t required although it
does make it significantly easier to read the diagram
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will be only one initial state in the activity
diagram
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Activity
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An activity, also known as an activity state, on a
UML Activity diagram typically represents the
invocation of an operation, a step in a business
process, or an entire business process.
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The rounded rectangles represent activities that
occur
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Flow / Edges
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The directed arrows on the diagram to show the
flow between activities to complete a workflow
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Vocabulary
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Join
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A black bar with several flows entering it and
one leaving it. All flows going into the join must
reach it before processing may continue. This
denotes the end of parallel processing.
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Fork – Parallel Activities
Ø A fork is used when multiple activities are
occurring at the same time
Ø A black bar with one flow going into it and several
leaving it
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Vocabulary of Activity Diagram
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Branch Decision:
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The branch describes what activities will take
place based on a set of conditions.
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It is represented by a diamond with one flow
entering and several leaving. The flows leaving
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Merging
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A diamond with several flows entering and one
leaving. The implication is that one or more
incoming flows must reach this point until
processing continues, based on any guards on the
outgoing flow.
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Basic Vocabulary
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Activity Final Node
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The filled circle with a border is the ending point.
An activity diagram can have zero or more activity
final nodes.
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Rule of Activity Diagram
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After the merge all of the parallel activities must
be combined by a join before transitioning into
the final activity state.
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Pictorial Representation of Vocabulary of
Activity Diagram
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Problem Statement
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NonComputer Science Scenario
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Consider the workflow associated with building a house.
First, you select a site. Next, you commission an architect
to design your house. After you've settled on the plan,
your developer asks for bids to price the house. Once
you agree on a price and a plan, construction can begin.
Permits are secured, ground is broken, the foundation is
poured, the framing is erected, and so on, until
everything is done. You're then handed the keys and a
certificate of occupancy, and you take possession of the
house
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Problem Statement
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In an order processing system, once the order is
received multiple activities are initiated to
complete the order process. On one side order
filing is initiated and on the other end billing
mechanism is initiated to receive the payment.
On the order filing side delivery mechanism is
finalized whether it is a rush delivery or regular
delivery. In the end all the activities end to close
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Possible Solution
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Swim Lanes
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At times it useful, especially when you are
modeling workflows of business processes, to
partition the activity states on an activity diagram
into groups
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Each group representing the business
organization responsible for those activities.
Each group is known as “Swim Lane”
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