CPSC-488 Book

What is a requirement?

A feature that the system must have or a constraint that it must satisfy to be accepted by the client.

What is requirements engineering?

 Process of defining the requirements of the system under construction.

What is the two main activities of requirements engineering?

Requirements elicitation and analysis.

What is requirements elicitation?

Process that results in the specification of the system that the client understands. Improves communication among developers, clients, and users to define a new system.

What is specification?

Formal document of what the system must do.

What is requirement analysis?

Process that results in an analysis model that the developers can interpret.

Why is requirements elicitation more challenging than requirements analysis?

It requires the collaboration of several groups of participants with different backgrounds.

Why are scenarios and use cases important?

Bridges the gap between the client knowing the domain but not software development and developers knowing software development but not the domain.

What is a scenario?

Describes an example of system use in terms of a series of interactions between the user and the system.

What are both scenarios and use cases written in?

Natural language.

What do devolpers first do?

Begins by observing/interviewing users in their environment to build a model of the application domain. During this phase, they represent the user’s current work processes as "as-is" scenarios.

What is application domain?

The activity the system is being built for. Includes the specific terms, rules, and actors used in that world.

• Terms: ISBN, Due Date, Borrower, Catalog, and Reservation

• Rules: A borrower cannot check out more than 10 books at once.

• Actors: Librarian, the Member, and perhaps an External Book Suppliers.

What is an ‘as-is’ scenario?

Represents the current work process before any new software is introduced. 

• Describes the reality of the library today.

What do developers do next after observing/interviewing users in their environment to build a model of the application domain?

 They then select understandable representations (scenarios and use cases) to describe the functionality to be provided by the future system. 

What is the final step in requirements elicitation?

The client validates the system description by reviewing the scenarios and testing simple prototypes provided by the developers to provide feedback.

Why are errors introduced during requirements elicitation are expensive to correct?

Because they are usually discovered late in the process.

What are some errors that are introduced during requirements elicitation?

Missing functionality of the system, functionality that was incorrectly specified, unusable user interfaces.

What does requirements elicitation focus on?

Describing the purpose of the system.

What is requirements specification?

The client, developers, and users identify a problem area and define a system that addresses the problem. Serves as a contract between the client and the developers

When is requirements specification structured and formalized?

During requirements analysis to produce an analysis model.

Requirements specification and analysis model contain the same what?

Information and system functionality but differ in language.

• Requirements specification is written in natural language.

• Analysis model is expressed in a formal notation.

Requirements elicitation and requirements analysis occur concurrently and iteratively.

What does requirements specification support?

The communication with the client and users. Analysis model supports the communication among developers.