Sequence diagram

.. uml::

    Browser -> Server: Authentication Request
    Server --> Browser: Authentication Response

    Browser -> Server: Another authentication Request
    Browser <-- Server: another authentication Response

->

is used to draw a message between two actors. The actors do not have to be declared explicitly.

-->

is used to draw a dotted line.

<- and <--

do not change the drawing, but may increase readability.

Note

This applies only to sequence diagrams. In other diagrams other rules may apply.