Question

What are the four types of messages and what are the differences between them in a sequence diagram?

Answer 1

Synchronous Message:

It requires a response before the interaction can continue.It is represented by line with a solid arrowhead pointing from one object to another.

Asynchronous Message:

It doesn't need a reply for interacttion to continue.It is represented by an arrow connecting two lifelines.

Reply or Return Message:

It is represented with a dotted line and an open arrowhead pointing back to the original object.

Self Message:

Sending message to self object.It is represented by U shaped arrow pointing back to itself.

Create Message:

It will create a new object.It is represented by dashed line and a open arrowhead that points to the rectangle representing the object created.

Delete Message:

It is used to destroy an object.It is represented by an arrow with an X at the end.

The above are the different types of messages used in sequence diagram.