Requirements Analysis 2. 1 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved INFO2005 Requirements Analysis Requirements Capture Department of Information Systems

Requirements Analysis 2. 2 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Lecture 2 - Learning Objectives v Identify the problems associated with Requirements Capture v Consider various fact-finding approaches

Requirements Analysis 2. 3 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Requirements Change v Why do requirements change? 

Requirements Analysis 2. 4 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved The impact of change 1X 1.5X - 6X 6X 60X - 60X -100X

Requirements Analysis 2. 5 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Why things go wrong Type of Failure Reason for FailureComment Quality Problems Productivity Problems Wrong problem addressed Wider influences are neglected Analysis carried out incorrectly Project undertaken for wrong reason Users change their mind External events change the environment Implementation is not feasible Poor project control From Bennett et. al. (1999)

Requirements Analysis 2. 6 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Requirements Capture v We will be considering requirements capture in the context of the Unified Process v All thetechniques may be used in conjunction with development method v The traditional techniques are known collectively as Fact-Finding Techniques

Requirements Analysis 2. 7 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Rational Unified Process “ The Rational Unified Process is a Software Engineering Process. It provides a disciplined approach to assigning tasks and responsibilities within a development organization. Its goal is to ensure the production of high-quality software that meets the needs of its end users, within a predictable schedule and budget. The Rational Unified Process captures many of the best practices in modern software development in a form that can be tailorable for a wide range of projects and organizations.” Rational Software Corportation - RUP v5.1.1

Requirements Analysis 2. 8 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Requirements in RUP

Requirements Analysis 2. 9 Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Fact-Finding Techniques v Remembering the techniques: –S... –Q... –I... –R... –O... v Not in order of importance, or sequence in the project

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v The most widely used traditional technique

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v Preparing for an interview v Time-consuming  ½ day preparation for one hour interview

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing “An effective, direct person-to-person interviewing technique requires that you have prepared a list of questions designed to gain an understanding of the real problems and potential solutions. To get as unbiased answers as possible, you need to make sure the questions you ask are context free. The context- free question is a high-level, abstract question that can be posed early in a project to obtain information about global properties of the user’s problem and potential solutions.” Rational Unified Process V5.1

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v A context-free question is:  Always appropriate.

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v Examples of context-free questions used to find actors:  Who is the customer?

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v Context-free questions that help understand business processes and requirements:  How do you take a customer order at the moment?

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v Examples of non-context-free questions are:  Leading questions: "You need a faster printer, don't you?"  Self answering questions: "Are fifty items about right?"

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v Conducting an interview  Introduce …  Permission …  Stay within agreed time  State objectives- keep them in mind  Show respect  Don’t dominate  But control direction

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v Conducting an interview  Be flexible  Seek evidence…  Open questions  “Reflect back”  Summarise  Can you return later?

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Interviewing v Ending the interview  Can I ask more questions later?  Would you be willing to participate in a requirements review?  Is there anything else I should be asking you? v Post-interview  Write up asap (1/2 day per interview)  Verify facts

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Sampling v Almost always used to support interviews –Adds –Can resolve –Identifies –Confirms –Identifies

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Sampling v Range from-  highly informal to…  rigorous statistical investigation -sample size chosen for significance v Informal: u collecting used documents

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Sampling v Formal Sampling u need to understand statistical theory to set up study and analyse data v In all cases, minimise disruption to users.

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Research / Reading v Particularly useful at start of project

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Observation v Less widely used –Observation can:

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Questionnaires v Questionnaires useful where:  Many people involved with system  Geographically dispersed

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Questionnaires v Also bear in mind:

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Documenting Requirements v Requirements must be carefully documented v Analyst’s notes must be: –summarised –organised –filed v One way to do this is to use a CASE tool –We will be using the Rational CASE tools.

Requirements Analysis Req. Capture b502.ppt © Copyright De Montfort University 2000 All Rights Reserved Summary In this session we have learned about various fact finding techniques - use the acronym SQIRO to help remember them. References: u Rational Unified Process u Bennett, S. et. al. “Object-Oriented Systems Analysis & Design using UML” McGraw-Hill 1999 Ch5 pp96–121