UML Sequence Diagrams - Activation Blocks - steps

Here are the steps for making a sequence diagram with activations


Start by drawing the actor initiating the activity and the participating classes and objects

Start the first activation block. An activation block representation of C# is any set of open and closed braces{}, such as for a method, try catch, if, foreach, etc

Next, add in the next message. Any place an arrow will terminate, before drawing in the arrow head, start the next activation block, then draw in the arrowhead pointing to that activation block(See Fig 4 and 5)

Once you have added all of the messages you want to show, finish off your activation blocks. Waiting until the end is easier, because you know how long they need to be.