How to Draw a UML Sequence Diagram

Learn how to draw a UML sequence diagram in 5 simple steps. See how you can visually describe object interactions of someone withdrawing money from an ATM. Model the dynamics of message passing between objects. Nail down the order in which the interactions occur.

  1. Step 1 - Define who will initiate the interaction

    Draw an actor on the diagram to specify who kick starts the interaction within a system.

  2. Step 2 - Draw the first message to a sub-system

    Specify the message sent from the actor who begins the interaction to the first point of contact in the system.

  3. Step 3 - Draw message to other sub-systems

    Send other messages between objects (i.e. lifelines) in the system.

  4. Step 4 - Draw reply message to actor

    Send reply messages back to the original callers upon receiving their messages.

  5. Step 5 - Send/Respond to anonymous actors

    Send messages to unknown receivers or receive messages from unknown senders.