This is usually drawn with a solid line and an open arrowhead. This illustrates a line with a solid arrowhead.Īsynchronous – A type of message that does not need a response from the receiver before the message gets back and carries another message. Synchronous – Represents a message where the sender waits for the response of the receiver before the message continues. It executes a task when a certain condition is met. Option loop – Rectangle symbol that represents a repetitive sequence in a system sequence diagram example. Lifeline – Is a vertical dashed line that represents the presence of an object over time. Object – Refers to the symbol in a system that describes how a class role will behave.Īctivation Bar – A rectangle shape placed on a lifeline that indicates the time or duration an object needs to finish a task. There are basic symbols, components, and types of message arrows that may occur in a UML sequence diagram example.Īctor – An external entity that interact with the system. System Sequence Diagram Examples and TutorialĪ sequence diagram is composed of elements and icons which you need to be familiar with in order to create one. Here in this post, we provided sequence diagram notations, sequence diagram examples, and a detailed instructional guide. What’s more, it gives developers an overview of the external actors including their order and the events they generate.

Each object passes on some messages to another in a sequential time or order of steps in a process. This is an interaction diagram that illustrates how objects in a system communicate with each other. Sequence diagram is one of the best ways to identify the requirements and processes of a system.

Uml sequence diagram tools