Complete the event description by adding information that is passed along with the event and the expected answer or response. Both of these elements are optional, that is, not every event requires parameters and not every event requires a response.
For example, an event called "notify" from one context might be as simple as an alarm with no parameters and no return. In another context, "notify" might mean "send a message and wait for a reply."
Convert event descriptions to operations
The goal of creating the sequence diagram is to discover and document the interfaces of each class. To define each interface fully, you must convert the event description to a formal operation signature.
The standard definition for an operation signature consists of a name, input parameters (or arguments), the expected return data type, and constraints.