In Rational Rhapsody, both events and messages create operations for a class. You can edit the operations created as a result of messages, but you cannot modify any event handlers.
Events and operations relate statecharts to the rest of the model by triggering transitions. Operations specified by a statechart are called triggered operations (as opposed to operations specified in object model diagrams, called primitive operations).
Events facilitate asynchronous collaborations and operations facilitate synchronous collaborations. Triggered operations have a return type and reply. Triggered operations have a higher priority than events.
In the rest of this guide, the term message means either an event or an operation.
Statecharts can react to operations and events that are part of the interface of a reactive class. Using a message as a trigger in a statechart to transition from state S1 to state S2 means that if the object is in S1 when it receives the message, it transitions to S2.
Events that do not trigger an active transition are ignored and discarded. If the object happens to be in state S3 when it receives the message and S3 does not reference the message, it ignores the message.
See Using events for more information.