The following discussion demonstrates how to define the structure and behavior of a business object from the requirements imposed by the business problem it belongs to. Each account should have contact information for a client such as name, street address, and email address. Clients must be able to create new accounts. Clients must be able to update contact information for their account. Clients must be able to retrieve information for their account.
Clients can retrieve and update only their own account information.
The account information must be maintained in persistent storage. Multiple clients must be able to access their account information at the same time. Multiple clients cannot update the same account concurrently. The first two requirements specify the structural attributes of the account object. Following these rules, the account object should have a field to hold account identification and several other fields to hold address, phone, and other contact information.