Sequence Diagram

[D Anthony]

Hello there, I'm trying to design a squence diagram to cancel library book reservation with the following scenarios
The (actor) enters the surname of  a customer. The system listss the full names and addresses of customers with that surname
The (actor) chooses a customer. The system lists the start and end dates of any reserves books for that customer and any outstanding fines
The (actor) selects a reservation for cancellation. The system asks the (actor) to confirm that the reservation should be cancelled
The (actor) confirms that the reservation is to be cancelled. The system deletes the reservation and confirms the deletion to the (actor).

I have attached what i have done but i would appreciate if i could have some feedback please, i.e is it correct, have i missed anything...

Thanks

[Junilu Lacar]

Seems like you have a number of things that are not quite right.

"... trying to design a sequence diagram..." - No, you don't design a sequence diagram. As with any other diagram of this nature, a sequence diagram is a communication tool. As such, it communicates your ideas of how certain aspects of a system are meant to work, i.e. the design. In other words, a diagram like this is meant to communicate aspects of the system's design.

A sequence diagram illustrates the sequence of method calls that are involved in performing a task to produce something useful for the actor(s) involved. Your diagram doesn't do this. The lifelines, which are the parallel vertical lines, represent different objects in the system that interact with each other.  The horizontal arrows depict messages, i.e. method calls, that are sent from one object to another so that each object can perform its part in completing the task. Your diagram doesn't depict this either. Instead, it looks like you are trying to use a sequence diagram (an object-oriented diagram) to depict some kind of hybrid data/logic flow chart (procedural).

I think it's best that you go back to your book/notes and figure out the purpose and proper use of a sequence diagram first.

[D Anthony]

Thank you for the feedback, you can tell this is not something i do on a regular basis:-)

Your comments are noted and very helpful in deed.

many thanks!