2. Activity Diagram
• Activity is a particular operation of the system.
• An Activity diagram is a dynamic diagram that shows
the activity and the event that causes the object to
be in the particular state.
• The diagrams describe the state of activities by
showing the sequence of activities performed.
• Activity diagrams can show activities that are
conditional or parallel.
3. Activity Diagram
• The purposes of 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.
4. Elements in Activity Diagram
Initial Activity: This shows the starting
point or first activity of the flow. Denoted
by a solid circle. This is similar to the
notation used for Initial State.
Activity: Represented by a rectangle with
rounded (almost oval) edges.
Decisions: Similar to flowcharts, a logic
where a decision is to be made is
depicted by a diamond, with the options
written on either sides of the arrows
emerging from the diamond, within box
brackets.
5. Elements in Activity Diagram
Concurrent Activities: Some
activities occur simultaneously
or in parallel. Such activities are
called concurrent activities. For
example, listening to the
lecturer and looking at the
blackboard is a parallel activity.
This is represented by a
horizontal split (thick dark line)
and the two concurrent
activities next to each other, and
the horizontal line again to show
the end of the parallel activity.
6. Elements in Activity Diagram
• Fork and Join Nodes
Forks and joins have the same notation: either a horizontal or
vertical bar (the orientation is dependent on whether the
control flow is running left to right or top to bottom). They
indicate the start and end of concurrent threads of control.
The following diagram shows an example of their use.
7. Elements in Activity Diagram
• Decision and Merge Nodes
Decision nodes and merge nodes have the same notation: a
diamond shape. They can both be named. The control flows
coming away from a decision node will have guard conditions
which will allow control to flow if the guard condition is met.
The following diagram shows use of a decision node and a
merge node.
8. Join node vs Merge node
• A join is different from a merge in that the join
synchronizes two inflows and produces a
single outflow. The outflow from a join cannot
execute until all inflows have been received. A
merge passes any control flows straight
through it.
9.
10.
11. • The following diagram is drawn with the four main
activities:
• Send order by the customer
• Receipt of the order
• Confirm order
• Dispatch order
• After 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.
12.
13.
14.
15. Activity Diagram vs. Other Diagrams
• Other 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.
• Activity 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 etc.
16. Sequence diagram vs. Activity Diagram
Sequence diagrams describe interactions among
objects in terms of an exchange of messages over time.
Sequence diagrams show a detailed flow for a specific
use case or even just part of a specific use case.
Activity diagrams illustrate the dynamic nature of a
system by modeling the flow of control from activity to
activity. An activity represents an operation on some
class in the system that results in a change in the state
of the system.
Editor's Notes
The diagram below shows a super-state. Both the Checking and Dispatching states can transition into the Canceled state, so a transition is shown from a super-state named Active to the state Cancel. By contrast, the state Dispatching can only transition to the Delivered state, so we show an arrow only from the Dispatching state to the Delivered state.
the first activity is to get dressed to leave for the lecture. A decision then has to be made, depending on the time available for the lecture to start, and the timings of the public trains (metra). If there is sufficient time to catch the train, then take the train; else, flag down a cab to the University. The final activity is to actually attend the lecture, after which the Activity diagram terminates.
A possible activity diagram for processing an order. The diagram shows the flow of actions in the system's workflow. Once the order is received the activities split into two parallel sets of activities. One side fills and sends the order while the other handles the billing. On the Fill Order side, the method of delivery is decided conditionally. Depending on the condition either the Overnight Delivery activity or the Regular Delivery activity is performed. Finally the parallel activities combine to close the order.
First, you enter the dates. Once you submit your desired flight plan, you can enter your personal information and at the same time the system could be searching availability. The system flow then joins back into one and you can select the specific flight on the dates you want to fly. This activity diagram gives you two different paths dependent on whether you are using reward points. After entering payment information, the system performs two processes at the same time and then sends out a confirmation email.
The activity diagram shows a typical event or class registration process for a client. This diagram uses notes to give more details about the initial and final states. After filling out the registration form, the client submits the form to a validation loop that is represented as a decision in the flow. If the information is correct, the system creates an account for the client and lets the client know about the creation of the account.
