Step 0 – Step 2
Mail Order Case Study
Use Case Modeling – Step 0: Developing the Problem Statement
In order to improve the operational efficiency of a mail order company, the chief executive officer is interested in computerizing the company’s business process. The major business activities of the company can be briefly described as follows:
A customer registers to become a member by filling in the membership form and mailing it to the company. A member who has not been active (no transactions) for a period of one year will be removed from the membership list and he/she needs to re-apply for reinstatement of the lapsed membership.
A member should inform the company of any change in personal details, such as home address, telephone numbers and etc.
A member can place an order by filling out a sales order form and faxes it to the company or by phoning the Customer Service Assistant with the order details.
The Customer Service Assistant first checks for the validity of membership and enters the sales order information into the system.
The Order Processing Clerk checks the availability of the ordered items and, if they are available, holds them for the order. When all the ordered items are available, the Order Processing Clerk will schedule their delivery.
The Inventory Control Clerk controls and maintains an appropriate level of stock and is also responsible for acquiring new items.
If there is a problem with an order, the member will phone the Customer Service Assistant, who will then take appropriate action to follow up the particular sales order.
Members may return defective goods within 30 days and get their money back.
The system will record the name of staff member who handles the transaction for future follow up action.
Figure 1 – Textual Analysis
Use Case Modeling – Step 1: Identifying Major Actors
If you carefully examine the problem statement, it is not difficult to identify the Customer Service Assistant, Order Processing Clerk and Inventory Clerk as the major users of the Mail Order System. The following actors of the system are identified:
- Customer Service Assistant
- Order Processing Clerk
- Inventory Control Clerk
A short paragraph should then be written to describe each of the actors.
Table 1 shows the specification of the Order Processing Clerk.
Actor Name:
Order Processing Clerk
Description:
The Order Processing Clerk is responsible for processing sales orders, submitting re-order requests, requesting necessary deposits from members, and scheduling the delivery of the goods to the member.
Table 1 – Specification of the Order Processing Clerk Actor
Figure 2 – Actor Description in Textual Analysis
Guidelines for Identifying Use Cases
Finding use cases is an iterative process. This process normally starts with interviewing the users (actors) who directly or indirectly interact with the system. Typically, it starts from bottom up, involving the customer to describe scenarios from their business activities. Each of these descriptions is a possible use case. These potential use cases can then be elaborated on, modified, broken into smaller use cases, or integrated into larger ones.
An important fact to remember is that people are generally not very forthcoming, and extracting useful information from the users is a skill that takes a lot of experience to acquire. The following questions may be useful in collecting information from users:
- What are the main tasks carried out by each actor?
- What data are manipulated and processed by the system?
- What problems is the system going to solve?
- What goals does an actor want to achieve using the system?
- What are the major problems with the current system and how could the proposed system simplify the work of the user?
- Guidelines for Naming Use Cases
The name of a use case consists of a verb and a noun or noun phrase in the following format:
Verb + Noun or Verb + Noun Phrase
The use case name describes an operation which achieves an observable user goal. For example, Place Order is a case use in an Order Process System, and Withdraw Money is also a use case for an ATM system. They are in the Verb + Noun format.
Figure 3 – Examples of Use Cases
Use Case Modeling – Step 2: Identifying Use Cases
By examining the responsibilities of the actors of the mail order system, the following use cases are identified:
- Check order status
- Place order
- Handle goods return
- Update membership record
- Archive membership
- Register new member
- Process order
- Schedule delivery
- Order goods
- Receive goods
- Deliver goods
- The complete initial use case model is shown in Figure 2.