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Applying Patterns: Select and Organize Problem-Domain Objects Connie’s Convenience Store 19
Participant-transaction
#3. “Participant-Transaction” Pattern transaction patterns
Participant
number
startDate
endDate
password
authorizationLevel
aboutMe
howMany
howMuch
rankTransactions
calcOverTransactions
isAuthorized
calcForMe
n 1
Transaction
number
date
time
status
aboutMe
calcForMe
rateMe
• Typical object interactions
howMany —> calcForMe calcOverTransactions —> calcForMe
howMuch —> calcForMe rankTransactions —> rateMe
• Examples
Participant: agent, applicant, buyer, cashier, clerk, client, civilian, customer, dealer,
delegate, distributor, donor, employee, investor, manufacturer, member, officer,
official, order clerk, owner, participant, policy holder, professional, prospect,
recipient, retailer, sales clerk, sales rep, shipper, student, subscriber,
supervisor, supplier, suspect, teacher, wholesaler, worker.
Transaction: agreement, assignment, authorization, contract, delivery, deposit,
incident, inquiry, order, payment, problem, report, purchase, refund, registration,
rental, reservation, sale, shift, shipment, subscription, time charge, title,
withdrawal.
• Combinations
actor-participant; participant-transaction; place-transaction; specific item–
transaction; transaction–transaction line item; transaction–subsequent
transaction.
That large, numbered box with a double border is a pattern box. You’ll see these boxes
from time-to-time, right when you need them, within the application chapters. The
number in the upper left corner is a pattern number; it’s there for easy reference. See
Chapter 7, “Strategies and Patterns Handbook,” for more.
Session and its participants
A session is a transaction object. What are its participants?
The participants are a cashier and a register. A cashier starts a session on a specific
register at a specific date and time.