1. Concept
Class diagram showing the most important business concepts and the relationships between them. Classes represent business concepts, but classes typically contain only important properties, not operations. Associations and generalizations show the relationship between these concepts.
2. The process of building a use case model
2.1 Discovering classes and objects
(1) Noun analysis method
Identify nouns and noun phrases in problem domains and use-case descriptions and use them as candidate concept classes or attributes.
Example:
Main success scenarios:
1. The customer brings the purchased goods to the POS machine charging port
2. The cashier starts a new sale
3. The cashier enters the product ID
4. The system records the list of commodity items sold, and displays the description, price and accumulated value of the commodity. Prices can be calculated based on a set of pricing specifications
The cashier repeats steps 3-4 until the end
5. The system displays the final total price
6. The cashier asks the customer to pay
7. The customer pays and the system processes the payment
8. The system records complete sales information and sends sales and payment information to external billing systems (for billing) and inventory systems
9. The system prints the receipt
10. Customer leaves with merchandise and receipt
noun: customer, purchased item, POS, cashier, new sale, item identification, item list, description, price, accumulated value, total price, payment, sales information, payment information, billing system, inventory system, receipt
Identify Objects: Customer, Merchandise, POS, Cashier, New Sales, Item List, Payment, Sales Information, Payment Information, Billing System, Inventory System, Receipt
Discarded objects: product identification, description, price, cumulative value, total price
2.2 Establish relationships between classes
(1) Association list method
A is physically or logically part of B;
A is a description of B
A is an item in transaction or item B
A is known to B / recorded by B / entered in B / captured by B
A is a member of B
A is an organizational subunit of B
A uses or manages B
A given B communication
A is related to a transaction B
A is a transaction related to another transaction B
A is adjacent to B
A is owned by B
A is an event related to B
2.3 Add important properties
1) First, enumerate the candidate attributes of the class from the perspective of the semantic integrity of the class;
2) Screen the candidate attributes of the class once according to the system goal and the role of the class in the system and the relevant characteristics of the problem domain;
3. Summary
The domain conceptual model is equivalent to a simplification of the class diagram, which has only some important properties and no operations.