Domain Modelling Cheat Sheet

Problem domain = The specific area (or domain) of the users’ business. Scope of the system.
Examples: products, sales, shippers, customers, invoices, payments
“Things” eventually modelled.

1. Identify a user and a set of use cases.
2. Brainstorm with user to ID things involved
3. Use the types of things (categ­ories) to system­ati­cally ask questions about potential things, such as the following: Are there any tangible things you store inform­ation about? Are there any locations involved? Are there roles played by people that you need to remember?
4. Continue to work with all types of users and stakeh­olders to expand the brains­torming list.
5. Merge the results, eliminate any duplic­ates, and compile an initial list.

Attribute: describes one piece of inform­ation about each instance of the class
Customer has first name, last name, phone number
Identifier or key: One attribute uniquely identifies an instance of the class. Required for data entities, optional for domain classes. Customer ID identifies a customer
Compound attribute: Two or more attributes combined into one structure to simplify the model.
Object: Class is a type of thing. Object is a specific instance of the class. Each instance has its own values for an attribute
Associ­ation (UML) / Relati­onship (ERD): a naturally occurring relati­onship between classes (UML term). # rep by Multip­lic­ity­/Ca­rdi­nality. 1 to 1 or 1 to many.

1. Using the use cases, actors, and other inform­ation about the system — including inputs and outputs — identify all nouns (names).
2. Using other inform­ation from existing systems, current proced­ures, and current reports or forms, add items or categories of inform­ation needed.
3. As this list of nouns builds, you will need to refine it. Ask these questions about each noun to help you decide whether you should include it:
- Ask questions, such as is it important and inside the scope, to see if it should be included.
- Ask questions to see if it really should be excluded, such as is it only a report or an input or is it an attribute.
- Ask questions to see if it needs further research. In other words that you cannot answer whether it needs to be included or excluded.
4. Create a master list of all nouns identified and then note whether each
one should be included, excluded, or researched further.
5. Review the list with users, stakeh­olders, and team members and then refine the list of things in the problem domain.