Requirements Determination CIS 4800 Kannan Mohan Department of CIS Zicklin School of Business, Baruch College Copyright © 2009 John Wiley & Sons, Inc. Copyright © 2009 Kannan Mohan

Learning Objectives What are requirements? Where do they come from? How do we get to them? Any issues? Where do they go?

What are requirements? What a system must do A property exhibited by software developed An observable characteristic of a desired system Should be about what and not how to do it (but in practice…?)

What are requirements? Types – Functional – what the system should do The ATM system shall facilitate cash withdrawal – Non-functional (quality) – a constraint placed on the system The ATM system shall validate transactions in less than 3 seconds

Nonfunctional Requirements

Non-Functional Requirements Correctness: Behaves as specified Adaptability: Ability to easily change to handle new situations Robustness: Behaves predictably for odd cases Stability: Copes with large amount of data Usability: Ease of use Maintainability, Compatibility, Portability etc.

Where do they come from? Clients Which stakeholders? Strategic Tactical Operational

How do we get to them? Interviews Questionnaires Observation Joint application development (JAD) Document analysis

Any issues? Selecting Appropriate Techniques

Any issues? Cognitive biases? – Anchoring and adjustment – Confirmation – Availability Complete? Consistent?

Where do they go? Specifications To the development team

Summary What is a requirement? What are different types of requirements? Provide examples for functional and non- functional requirements. Assess the various requirements determination techniques based on various factors.