Modelling an object as Session Bean or Entity Bean ?

[Francesco]

Hi all !
I'm modelling an application for selling tickets on-line.
Tickets are booked on-line then the user navigates to the payment page
and pays with credit card.

The business analyst decided to allow a 30 minutes reservation time for
people who booked the ticket to pay with credit card.

If time elapses the seat "lock" is released.

I think there should be an EJB responsible to keep up with Seat
reservations.

My dilemma is : should I model it as Session Bean or Entity Bean ?
I initially modelled it as Session Bean with plain (Insert/Update) of
the Seats Table when the ticket is booked / paid / time elapsed

On the other hand I think, if there's multi-user access of the PK
(SeatId),
an Entity Bean should be used.

What do you say to it ? Session Bean or Entity Bean ?
Thanks in advance
Francesco

 

[wesley.hall]

Hi all !
I'm modelling an application for selling tickets on-line.
Tickets are booked on-line then the user navigates to the payment page
and pays with credit card.

The business analyst decided to allow a 30 minutes reservation time for
people who booked the ticket to pay with credit card.

If time elapses the seat "lock" is released.

I think there should be an EJB responsible to keep up with Seat
reservations.

My dilemma is : should I model it as Session Bean or Entity Bean ?
I initially modelled it as Session Bean with plain (Insert/Update) of
the Seats Table when the ticket is booked / paid / time elapsed

On the other hand I think, if there's multi-user access of the PK
(SeatId),
an Entity Bean should be used.

What do you say to it ? Session Bean or Entity Bean ?
Thanks in advance
Francesco

It should be an entity bean.

 

[Danno]

Hi all !
I'm modelling an application for selling tickets on-line.
Tickets are booked on-line then the user navigates to the payment page
and pays with credit card.

The business analyst decided to allow a 30 minutes reservation time for
people who booked the ticket to pay with credit card.

If time elapses the seat "lock" is released.

I think there should be an EJB responsible to keep up with Seat
reservations.

My dilemma is : should I model it as Session Bean or Entity Bean ?
I initially modelled it as Session Bean with plain (Insert/Update) of
the Seats Table when the ticket is booked / paid / time elapsed

On the other hand I think, if there's multi-user access of the PK
(SeatId),
an Entity Bean should be used.

What do you say to it ? Session Bean or Entity Bean ?
Thanks in advance
Francesco

Wesley is correct, the ticket should be an entity bean. I just want to
also mention that session beans are verbs (reserveTicket, buyTicket,
surrenderTicket, isAvailable) and entity beans are nouns (customer,
ticket, creditCard, address).

 

[wesley.hall]

Wesley is correct, the ticket should be an entity bean. I just want to
also mention that session beans are verbs (reserveTicket, buyTicket,
surrenderTicket, isAvailable) and entity beans are nouns (customer,
ticket, creditCard, address).

Danno,

I feel really bad disagreeing with you after you so nicely called me
'correct' but disagree I must

While I see where you are coming from, it can be dangerous to think in
this way. Firstly, every item in your list of 'session beans' would not
be a bean in it's own right, just a method on a bean.

Your examples of entitities are OK, but it is not correct to say
'entity beans are nouns'. What about ShoppingCart? This is a noun, but
I certainly wouldn't fault anyone for implementing it at a stateful
session bean (infact, I would have a few questions if they used an
entity).

If you want a general rule to follow, then yes generally nouns are
usually modelled as entities (but certainly not all nouns).

A general rule for session beans is much harder to pin down, they might
also be nouns (ShoppingCart) or roles (BookingAgent), or just a generic
collection of related functions (LogHandler).

The only real rule you can follow is... "Session beans hold no state or
state private to the user (stateless/stateful) and do not support
concurrency. Entity beans hold shared state and are fully concurrent".