The best way to understand sequence diagrams is to look at some examples of sequence diagrams. A tool called UJECTOR for automatic translation of UML models to executable Java code, which uses UML class diagram, sequence diagrams and activity diagrams for automated code generation and shows that the generated code is consistent with U ML models, fully functional, and understandable. It's shown by an arrow going from a lifeline to an endpoint, a filled circle or an x. It can be shown by an arrow with an x at the end.Ī message sent from an unknown recipient, shown by an arrow from an endpoint to a lifeline.Ī message sent to an unknown recipient. This is a message that destroys an object. Similar to a return message, it's depicted with a dashed line and an open arrowhead that points to the rectangle representing the object created. This is a message that creates a new object.
Like synchronous messages, they are drawn with an arrow connecting two lifelines however, the arrowhead is usually open and there's no return message depicted.Ī reply message is drawn with a dotted line and an open arrowhead pointing back to the original lifeline.Ī message an object sends to itself, usually shown as a U shaped arrow pointing back to itself. It's usually drawn using a line with a solid arrowhead pointing from one object to another.Īsynchronous messages don't need a reply for interaction to continue. Ī synchronous message requires a response before the interaction can continue. Place the condition for exiting the loop at the bottom left corner in square brackets. When that object's lifeline ends, you can place an X at the end of its lifeline to denote a destruction occurrence.Ī repetition or loop within a sequence diagram is depicted as a rectangle. Objects can be terminated early using an arrow labeled ">" that points to an X. Lifelines are vertical dashed lines that indicate the object's presence over time. Asynchronous messages are sent from an object that will not wait for a response from the receiver before continuing its tasks. Use half-arrowed lines to represent asynchronous messages. The relevant snippets of source code are shown below the diagram.
It starts with a call to the method calcTotal () of the Sale class.
UML SEQUENCE DIAGRAM GENERATOR JAVA SOFTWARE
The canonical case is a UML Sequence Diagram (where the notation comes from), which represents the messages exchanged between objects in a software system. Typically, they represent events sent and received between some entities over time. Figure 2 shows a sequence diagram for calculating the total of a sale transaction. As their name says, sequence diagrams are meant to represent ordered sequences of elements. Messages are arrows that represent communication between objects. UML sequence diagrams typically show some sequence of method invocations that achieve some specific purpose. When an object is busy executing a process or waiting for a reply message, use a thin gray rectangle placed vertically on its lifeline. Use the UML object symbol to illustrate class roles, but don't list object attributes.Īctivation boxes represent the time an object needs to complete a task. Start Now Basic Sequence Diagram NotationsĬlass roles describe the way an object will behave in context.
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