The Library's Create Loan Card

In practice

The header is REQ, LOAN, zero one, Create Loan. The business statement says staff and kiosks must be able to lend an item to a member, so that the library knows who has each item, when it is due back, and which loan rules applied. The material focus is the Loan, with the Member, the Item, the Branch and the Loan Policy Version as related things. The change type is create. The properties are grouped. Under parties come the member and the item, both required. Under timing come the checkout date, set automatically, and the due date, calculated from the loan policy version in force. Under place comes the branch where the loan began. Under rules comes the policy version, recorded on the loan itself. The constraints come next. The member's card must be active. The item must be available, or on hold for this member. A member may hold no more than the policy's maximum number of loans. Laptops may be lent only to adult members. The precondition is a member identified at the desk or kiosk. The outcome is that the item's status becomes on loan and a log entry is written. The example: a member borrows a laptop at the main branch, and the system sets a seven-day loan from the current laptop rules.