UML Activity Diagram
diagram is another important diagram in UML to describe dynamic aspects of the
diagram is basically a flow chart to represent the flow form one activity to
another activity. The activity can be described as an operation of the system.
the control flow is drawn from one operation to another. This flow can be
sequential, branched or concurrent. Activity diagrams deals with all type of
flow control by using different elements like fork, join etc.
basic purposes of activity diagrams are similar to other four diagrams. It
captures the dynamic behaviour of the system. Other four diagrams are used to
show the message flow from one object to another but activity diagram is used
to show message flow from one activity to another
is a particular operation of the system. Activity diagrams are not only used for
visualizing 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 activity diagram is the message part.
does not show any message flow from one activity to another. Activity diagram
is some time considered as the flow chart. Although the diagrams looks like a
flow chart but it is not. It shows different flow like parallel, branched,
concurrent and single.
the purposes can be described as:
the activity flow of a system.
the sequence from one activity to another.
the parallel, branched and concurrent flow of the system.
to draw Component Diagram?
diagrams are mainly used as a flow chart consists of activities performed by
the system. But activity diagram are not exactly a flow chart as they have some
additional capabilities. These additional capabilities include branching,
parallel flow, swimlane etc.
drawing an activity diagram we must have a clear understanding about the
elements used in activity diagram. The main element of an activity diagram is
the activity itself. An activity is a function performed by the system. After
identifying the activities we need to understand how they are associated with
constraints and conditions.
before drawing an activity diagram we should identify the following elements:
the above mentioned parameters are identified we need to make a mental layout
of the entire flow. This mental layout is then transformed into an activity
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. The activity diagram is made
to understand the flow of activities and mainly used by the business users
following diagram is drawn with the four main activities:
order by the customer
of the order
receiving the order request condition checks are performed to check if it is
normal or special order. After the type of order is identified dispatch
activity is performed and that is marked as the termination of the process.
to use Interaction Diagrams?
basic usage of activity diagram is similar to other four UML diagrams. The
specific usage is to model the control flow from one activity to another. This
control flow does not include messages.
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 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.
we will look into the practical applications of the activity diagram. From the
above discussion it is clear that an activity diagram is drawn from a very high
level. So it gives high level view of a system. This high level view is mainly
for business users or any other person who is not a technical person.
diagram is used to model the activities which are nothing but business
requirements. So the diagram has more impact on business understanding rather
are the main usages of activity diagram:
work flow by using activities.
level understanding of the system's functionalities.
business requirements at a later stage