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Use Case Modeling – Step 5: Performing a Textual Analysis

A textual analysis need to be performed for each of all the use cases based on their descriptions, yielding a set of candidate classes in the process. These classes will then be considered for inclusion in the domain class model which serves as a preliminary class model for the future development of the initial class model.

A textual analysis on the Process Order use case is demonstrated in Table 4. All the nouns and noun phrases have been underlined in the brief use case description.

Use Case:

Schedule Delivery

Use Case ID:

UC-300

Actor:

Order Processing Clerk

Description:

The Order Processing Clerk selects an order from the list of filled sales orders. The system displays the sales order details, and the member’s telephone number and address are displayed. The Order Processing Clerk enters the delivery date and time after talking with the member over the phone. The system records the delivery date and time in a dispatch request to the delivery team.

Table 4 – Textual Analysis on the Schedule Delivery Use Case

Note: Recall that a use case model often consists of several use cases. Each of the use cases has its own corresponding use case description, including its brief description and the flow of events, providing more details. As you progress in the development of the project, more and more use case will be developed according to the use case schedule. Refine and enrich the initial class model iteratively and incrementally by performing the textual analysis for each of the use cases that you have developed.

Figure 6 – Initial Class Model

Expanding on the Initial Use Case Model

The initial use case model is expanded incrementally in subsequent phases of the system development life cycle. In each phase, some use cases are selected and analyzed to produce detailed specifications of the necessary behavioral and functional requirements. Common behaviors and alternative behaviors of use cases are identified when the use cases are expanded and analyzed. These behaviors are extracted to become inclusion, extension and generalization use cases. The inclusion, extension and generalization use cases help to make the use case model more maintainable. The classes identified in the analysis of the use cases are used to update and refine the class model.

Use Case Modeling – Step 6: Developing Base Use Case Descriptions

Table 5 shows a use case description for an order processing system. In this example, the use case name is Place Order. Along with the name, you need to provide a brief description of each use case.  The pre-condition can effectively reduce the complexity of the use case.  For example, as a registered member, one must already have a valid account.  Consequently, many alternative situations such as invalid account, account on-hold etc will not be applicable to valid members.

Table 5 – Description for the Place Order Use Case