Unfolded composite

SalesChain

Customer

pocket

Wholesaler

till

action pay (retailer, wholesaler, amount)pre retailer.till> amountpost retailer.till ñ= amount&& wholesaler.till += amount

Thing

price

Owner

stock

1

*

action supply (wholesaler, retailer, thing)pre wholesaler.stock includes thingpost wholesaler.stock ñ= thing&& retailer.stock += thing

Retailer

till

action pay (customer, retailer, amount)pre customer.pocket> amountpost customer.pocket ñ= amount&& retailer.till += amount

action supply (retailer, customer, thing)pre retailer.stock includes thingpost retailer.stock ñ= thing&& customer.stock += thing

pay

supply

supply

pay

Previous slide

Next slide

Back to first slide

View graphic version

The resulting model (ìunfoldingî).

Notice how the till of the Retailer is now affected by both sets of actions: as we said at the beginning of this section, the state of an object is where the collaborations it takes part in interact.

Notice that these are specifications: it is still up to the designer of each type to produce a class matching the resulting spec.