Requirements by Pattern

Specify Intent

The intent of the Specify pattern is to describe how an actor can identify an object in the application. Specify enables authors to independently focus on methods to identify information and perform operations on that information.

Also Known As

Specified, Locate

Motivation

In applications, the author often wants to describe a method to identify a piece of data. Take the example of a car insurance company's customer-care application. When a customer calls with questions, the first activity the customer-care representative handles is collecting data from the customer to identify him in the system. For instance, the first question is often, "What is your name?" The customer-care representative enters the response into the application. In turn, the application provides a list of hits or, in the case of an exact hit, the information pertaining to the customer.

The problem arises when trying to talk about this activity without disclosing any implementation details. To remedy this, it is sufficient to require that the application enable users to "specify" some piece of information. For the customer-care application described previously, the solution is as follows:

Specify Customer

Specify Customer with Last Name

The Customer Care application will enable the Userto specify a Customer with the Customer's last name.

Later in the document, the author may refer to this feature as follows:

Change Customer Information

Change Customer Name

The Customer Care application will enable the user to change the name of a User-specified customer.

Applicability

Use Specify when: The intent of the Specify pattern is to describe the means an application provides to a user to identify an object. Specify enables authors to independently focus on methods to identify information and performing operations on that information.

Consequences

Specify has the following benefits and liabilities:

Convenient reference. Most specifications include discussions of locating or identifying a piece of information and then performing some operation on it. The pattern reduces the coupling between the operation and the specification, enabling the author to focus on the two aspects of data management independently.

Example Implementations

Examples of ways to implement Specify include:

• The File window used prevalently throughout Microsoft's Windows applications. In this case, the specification method may consist of highlighting a presented file name or typing one in.

• Many of the internet search engines provide rich methods for specifying information. These methods include wildcard keys and Boolean expressions. Once the user enters the search criteria, most search engines then provide a list and the user is guided to specify the information they want to view by pointing and clicking with their mouse.