Sequence Diagrams Are: There are 5 Important Components in them

One type of diagram in the unified modeling language is sequence. Sequence diagrams are diagrams that explain interactions between objects in a system. 

So, what are the goals and components in this type of diagram?  

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Sequence Diagram Is 

It can be interpreted that a sequence diagram is an example of a UML diagram that shows the interactions between components in a process visually. 

This type of diagram will display the sequence of actions and communication of each component in the system, such as users and objects. 

Each component in the sequence diagram is depicted via a vertical line. Then, there are messages exchanged between these components via horizontal lines. 

Meanwhile, the main purpose of creating a sequence is to determine the sequence of events. In addition, this diagram will illustrate the flow of data in more detail. 

Components in Sequence Diagrams

The following are some of the components in a sequence diagram : 

Actor 

The first component is an actor that describes the user who interacts with the system. In this type of diagram, actors are depicted using stick figure symbols. 

Activation box 

The activation box represents the time required for the object to complete its task. The longer the time, the longer the activation box will be. 

The activation box component is depicted using a rectangle.  

Lifelines 

Meanwhile, for the lifeline, use the sequence diagram symbol in the form of a dotted line. This lifeline describes the activity of an object. 

Object 

The next component of the sequence diagram is the object depicted with a box symbol. The function of objects is to document the behavior of objects in a system. 

Messages 

Meanwhile, messages are the final component to describe the communication carried out by objects. Sequential messages appear on the lifeline. 

The message component is depicted with an arrow symbol which is the core of the diagram. 

Example of Sequence Diagram 

To make it easier for you to understand, look at the example of a sequence diagram on a shopping card. This diagram involves customers as actors. 

Meanwhile, the three objects are shopping cards, orders and goods items. The sequence diagram begins with the customer sending a message to the Lifeline shopping card. 

The next process is, the lifeline will send messages to other lifelines including the order section. Meanwhile, the shopping card diagram depicts interactions between objects. 

Considering their function, sequence diagrams are important to learn. So, you can create applications that work well.