Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved INFO2005 Requirements Analysis Systems Development Methodologies Department of Information Systems

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Learning Objectives v Explain what is meant by methodology v Examine benefits and limitations v Consider alternative views of lifecycles v A brief review of exemplar methodologies

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Systems Development Methodologies ‘a methodology is a collection of procedures, techniques, tools and documentation aids, supported by a philosophy, which will help the systems developers in their efforts to implement a new information system’ (Avison & Fitzgerald) ‘a set of principles of method, which in any particular situation has to be reduced to a method uniquely suited to that particular situation’ (Checkland)

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Levels of abstraction Bennett, McRobb, Farmer 1999

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Systems Development Methodologies v A methodology comprises: –Phases & Sub-phases –Techniques & Tools –Guidance on how to use the techniques & tools at each stage within a phase or sub- phase –Specified deliverables –How the project will be management –An all encompassing philosophy

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Systems Development Methodologies  Survey of software developers across Europe : -

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Why use a methodology? v Better systems v Use of a methodology better than none at all v Aim to improve

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Objectives  Objectives of a methodology:

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Systems Development Methodologies  The techniques need to possess: – notational accuracy – notational simplicity – an appropriate semantic v Use of a methodology still does not solve all the problems of system development

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Systems Development Methodologies  User training necessary v Commercially packaged products usually include:- - manuals - education and training - consultancy support - automated tools - pro forma documents - model building templates

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Benefits of Methodological Approach v Standardised process v Benefits

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Benefits vProduce a better quality product: vHelp to ensure user requirements are met completely.

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Benefits vHelps the project manager, by giving vPromote communication between project participants by

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Limitations v Methodologies vary widely e.g. v No guarantee of success v Quality of developers most important v Methodological fashion changes !

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Limitations v Applicability of methodology depends on –type of application –size of system –complexity –technology being used –experience & training of developers –and other factors … v It is important to choose a suitable methodology

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Different Perspectives v Methodologies differ in

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Unified Process v Unified Process has four phases –Inception –Elaboration –Construction –Transition v It uses UML

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Unified Process v What are its workflows:

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved DSDM v Dynamic Systems Development Method v Suggests a slightly different view of the lifecycle than UP v Fundamentally iterative

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved DSDM

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved SSADM v Structured Systems Analysis and Design Method - version 1 launched in 1981 v Developed, funded and controlled by CCTA v Version 4+ produced in v Latest version is 4.3 CCTA = Central Computing and Telecommunications Agency

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved SSADM v Comprises: v Uses traditional techniques - DFD, E-R etc.

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Yourdon v Developed during 70’s & 80’s –Many contributors including Ed Yourdon v Structured, various flavours including real-time. v Uses similar techniques to SSADM

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Real-Time Yourdon v Methodology developed from work of –De Marco –Constantine & Yourdon –Chen & Flavin –MacMenamin & Palmer v Developed by –Ward & Mellor –Hatley & Pirbhai

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Real-Time Yourdon v The methodology comprises –Essential Model –Implementation Model

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Real-Time Yourdon v Structured Analysis & Design is based upon 3 perspectives

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved Summary v Explain what is meant by methodology v Examine benefits and limitations v Consider alternative views of lifecycles v A brief review of exemplar methodologies

Requirements Analysis SDM b518.ppt © Copyright De Montfort University 2000 All Rights Reserved References v Bennett, S., McRobb, S. & Farmer, R. Object-Oriented Systems Analysis and Design using UML McGraw-Hill 2002, (Ch 22) v Jacobson, I., Booch, G. and Rumbaugh, J. (1999), The Unified Software Development Process, Addison-Wesley, Reading Mass. (Ch 7) v Rational Unified Process 2000 v Avison, D.E., Fitzgerald, G. (1995) Information Systems Development: methodologies, techniques and tools, 2nd. Ed. McGraw-Hill