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Overall Systems Development Process

08/06/2012. Overall Systems Development Process II. 2. Learning Objectives. Describe the traditional systems development lifecycle (waterfall model)Identify cross-lifecycle activitiesIdentify key stages of all development lifecycles Identify the typical outputs of a systems development lifecycle.

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Overall Systems Development Process

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    1. Overall Systems Development Process Dr Jon Tepper Room N330 Hello everyone, my name is Jon Tepper. Some of you may already know me from your Level I and II of your course. However, for those who do not, you can normally find me in room N411 of the Newton Building. As you are aware, you will soon be entering Level III and thus the final year of your degree. Level III consists of an individual project supported by two compulsory modules on design and quality. It also consists of a number of optional modules selected by yourself one of these being Artificial Intelligence - which is the one I would like to interest YOU in.Hello everyone, my name is Jon Tepper. Some of you may already know me from your Level I and II of your course. However, for those who do not, you can normally find me in room N411 of the Newton Building. As you are aware, you will soon be entering Level III and thus the final year of your degree. Level III consists of an individual project supported by two compulsory modules on design and quality. It also consists of a number of optional modules selected by yourself one of these being Artificial Intelligence - which is the one I would like to interest YOU in.

    2. 08/06/2012 Overall Systems Development Process II 2 Learning Objectives Describe the traditional systems development lifecycle (waterfall model) Identify cross-lifecycle activities Identify key stages of all development lifecycles Identify the typical outputs of a systems development lifecycle

    3. 08/06/2012 Overall Systems Development Process II 3 Learning Objectives Discuss the problems associated with the traditional waterfall model Explain Prototyping and its advantages and disadvantages Identify the different stakeholders in a systems development project

    5. 08/06/2012 Overall Systems Development Process II 5 Project Identification & Selection Someone (system owners or users) initiates a project by identifying the need for a new or enhanced system Could be at corporate-level e.g. to convert keyboard input to barcode input Projects can be planned or unplanned Planned – plan to select system development project that provides most benefits Unplanned – easily overwhelms organisation and must be screened and prioritised by IT managers

    6. 08/06/2012 Overall Systems Development Process II 6 Project Initiation & Planning Further investigation to determine if project is worth pursuing What are the risks? What is the project scope? Project leader and systems analysts will draw up a plan for management Can the IT dept develop the solution with resources available? Project leader and some team members will evaluate feasibility and present this information to system owner

    8. 08/06/2012 Overall Systems Development Process II 8 Analysis Current system is studied and alternative or replacement systems are proposed Problem analysis – systems analyst must understand problem and present to management Requirements analysis – what data must be captured and stored? What must the system do? Decision analysis – How much of the system must be computerised? Should we buy or build it? What technology should we use? Is the web required?

    10. 08/06/2012 Overall Systems Development Process II 10 Design Description of the recommended solution is converted into logical and then physical system specifications How will technology be used in the new system? What ideas and opinions do users, vendors & IT specialists have? Designs must adhere to internal technical design standards that ensure completeness, usability, reliability, performance and quality Technology based views of data,processes & interfaces

    12. 08/06/2012 Overall Systems Development Process II 12 Implementation System specifications are converted into a working system that is tested and used The computer-based system is coded, tested and installed within the organisation. Coding : programmers produce programs that make up the system Testing : programmers and test engineers test individual programs and the entire system to find and correct errors Installation : new system becomes part of daily activities of the organisation. Application software is installed onto new or existing hardware User Training & Support : finalisation of documentation & training

    15. 08/06/2012 Overall Systems Development Process II 15 Operation and Support Once the system is operating, it delivers the business solution to the user community It will require on-going system support for the remainder of its life Systems support (maintenance) consists of : Technical support User support Fixing software errors (bugs) Recovering the system after a crash Adapting the system to new requirements Eventually user feedback and problems indicate its time to start over and reinvent the system (system entropy reached!)

    16. 08/06/2012 Overall Systems Development Process II 16 Process of Maintenance Four major activities occur within maintenance (support): Obtaining maintenance requests Transforming requests into changes Designing changes Implementing changes Remember: by definition the SDLC is cyclic, therefore the last activity leads back to the first and then repeating development steps until the change is implemented – see Hoffer et al (2001) pp 619, fig18.4: Deliverables will thus be produced at each SDLC phase

    17. 08/06/2012 Overall Systems Development Process II 17 Cross Life Cycle Activities Activities that overlap many or all phases of the methodology : Fact finding : research, interviews, questionnaires etc Documentation & presentations : recording facts and specifications. Presenting findings to management. Estimation & measurement Feasibility analysis Project and process management Change management Quality management

    18. 08/06/2012 Overall Systems Development Process II 18 SDLC Outputs

    19. 08/06/2012 Overall Systems Development Process II 19 Key Stages of All SDLCs More Generally Life of a computer-based system can always be divided into two key stages : Systems development Analyse, design and build it! Systems operation and support Use it, keep it running and support it! Eventually you cycle back from operation and support to redevelopment

    20. 08/06/2012 Overall Systems Development Process II 20 Is A Lifecycle A Methodology? Whitten et al (2001) states that a systems development methodology implements the development stages of the 2 general phases of an SDLC So are the terms methodology and life cycle abused in ISAD? What do you think?

    21. 08/06/2012 Overall Systems Development Process II 21 Problems with Waterfall Model Iteration complicates manageability Working guidelines and rules inflexible : change a user or system requirement you must go to initial phase and propagate changes through each phase Amount of documentation produced makes it difficult for users and analysts to see overall picture Long development times May take years to develop a complex software system - by which business needs, priorities and market place may change Use of parallelism may minimise these limitations

    22. 08/06/2012 Overall Systems Development Process II 22 Prototyping An iterative process of systems development in which requirements are converted to a working system which is continually revised through close work between an analyst and the users Since prototyping is only a small-scale version of the whole system some features and functionality may be omitted Prototypes typically contain the Graphical User Interface (GUI) and partial functionality

    24. 08/06/2012 Overall Systems Development Process II 24 Prototyping Complements SDLC Prototyping can be used to complement a traditional structured SDLC A prototype could be developed early on in the analysis and design phase to help identify user requirements The final system developed is based on the specification of the prototype Prototyping is an excellent method for accurately determining user requirements

    25. 08/06/2012 Overall Systems Development Process II 25 Prototyping Tools Computer-aided Software Engineering (CASE) tools are software tools that help the analyst through each phase of the SDLC e.g., to construct system designs, code or tests A prototype can be developed using such CASE tools as 4th Generation Languages (4GLs) Allows graphical construction of prototype via query, screen and report design tools rather than writing code from scratch Examples., Borland Delphi : visual editing of GUI, creation of database apps, programming with object-orientated Pascal; Borland C++ Builder : same as Delphi but uses C++ instead of Pascal; Microsoft Visual Basic : same as Delphi but uses BASIC

    26. 08/06/2012 Overall Systems Development Process II 26 Advantages of Prototyping Shortened development times Less chance for business or system requirement changes Reduced development costs Allows users to be actively involved in the analysis and design phases : Users can see and experiment with the system thus solving problem of trying to understand system through endless documentation Visual nature of the prototype creates an understanding of the system that would be difficult to achieve from paper diagrams & written documentation

    27. 08/06/2012 Overall Systems Development Process II 27 Disadvantages of Prototyping The term Rapid Application Development (RAD) is used to market the prototyping products and attracts criticisms of it not being a ‘serious’ method i.e. it’s for hackers! Name refers to projects that complete quicker than when using traditional SDLC but 4GL tool vendors use RAD as a buzzword to sell products 4GL tools can tempt application programmers to avoid structure analysis and design techniques Result : inconsistencies between system modules, non compliance with standards, non-functional requirements not expressed, lack of safety features Users may not give up prototype Users want analysts to use RAD techniques as they want the system as quick as possible - probably at the expense of quality!

    28. 08/06/2012 Overall Systems Development Process II 28 Stakeholders and their Roles A stakeholder is any person who has an interest in an existing or new computer-based system. Stakeholders can be technical or non-technical workers For information systems, the stakeholders can be classified as : System owners System users Systems analysts System designers System builders (programmers!) IT vendors and consultants

    29. 08/06/2012 Overall Systems Development Process II 29 Summary Describe the traditional systems development lifecycle (waterfall model) Identify cross-lifecycle activities Identify key stages of all development lifecycles Identify the typical outputs of a systems development lifecycle

    30. 08/06/2012 Overall Systems Development Process II 30 Summary Discuss the problems associated with the traditional waterfall model Explain Prototyping and its advantages and disadvantages Identify the different stakeholders in a systems development project

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