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Software development process


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All about developing a reliable software!

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Software development process

  1. 1. Software Development Process<br /> Its Phases and Overview<br />
  2. 2. Introduction<br />This document describes the (SDLC) for small to medium database application development efforts.<br /><ul><li>This chapter presents an overview of the SDLC, alternate lifecycle models, and associated references.
  3. 3. The following project describes the internal processes that are common across all stages of the SDLC, and the third chapter describes the inputs, outputs, and processes of each stage. </li></ul>SYIT 191-200<br />2<br />
  4. 4. Cont:<br />There are six stages in SDLC:<br /> Analysis<br /> Planning<br /> Design <br /> Coding<br /> Testing<br /> Implementation & maintenance<br />SDLC uses four main approaches viz.<br />SYIT 191-200<br />3<br />
  5. 5. cont<br />Waterfall Approach<br />Spiral Approach<br />Incremental Approach<br />Win Win Spiral Approach<br />SYIT 191-200<br />4<br />
  6. 6. Meaning And Methodologies<br />5<br />CONCEPT OF SDLC <br />
  7. 7. Contemplative Questions<br />What are the various approaches to developing Information Systems?<br />Is there one best way?<br />What is the difference between techniques, methodologies and tools?<br />What does the popular term “SDLC” actually mean?<br />SYIT 191-200<br />6<br />
  8. 8. SDLC<br />SDLC stands for <br />Systems <br />Development <br />Life <br />Cycle<br />What does it mean?<br />Why do we need it?<br />SYIT 191-200<br />7<br />
  9. 9. What is SDLC?<br />SDLC stands for <br />Systems Development Life Cycle<br />First, SDLC is a Life Cycle.<br />All systems have a life cycle or a series of stages they naturally undergo.  <br />The number and name of the stages varies, but the primary stages are conception, development, maturity and decline. <br />The systems development life cycle (SDLC) therefore, refers to the development stage of the system’s life cycle<br />SYIT 191-200<br />8<br />
  10. 10. Approaches to Systems Development<br />Process-Oriented Approach<br />Focus is on flow, use and transformation of data in an information system<br />Involves creating graphical representations such as data flow diagrams and charts<br />Data are tracked from sources, through intermediate steps and to final destinations<br />Natural structure of data is not specified<br />Disadvantage: data files are tied to specific applications<br />SYIT 191-200<br />9<br />
  11. 11. Cont Which is better, the Process Approach or the Data Approach<br />Process Approach:<br /> “Let’s look at all of our processes. Processes take precedence over data. Get the processes correct first. Then we’ll address what data is important.”<br /><ul><li>Data Approach :</li></ul>“Forget the processes, let’s look at the data. Data comes first. Get the data correct, then see how the processes actually use the data<br />SYIT 191-200<br />10<br />
  12. 12. Its Phases and Overview<br />Milestone In SDLC<br />
  13. 13. Milestones<br />Following are the milestones in SDLC –<br />Requirement Gathering<br />In this, customer needs are analysed in order to get a clear picture of the user requirements. If it is an existing system, requirements include improvement on the backlogs of the existing system.<br /> This is done by interviewing users and consultants of the the company (client).<br />SYIT 191-200<br />12<br />
  14. 14. Cont:<br />Functional Specification<br /> It mentions, what functions is the product supposed to have i.e how the interface should be, what should the product do, how will the user use the product.<br />SYIT 191-200<br />13<br />
  15. 15. High Level Design (HLD)<br />In this stage, logical view of the solution to customer requirements is arrived at. It helps in deciding operating systems, hardware, database design, architecture, security issues etc.<br />SYIT 191-200<br />14<br />
  16. 16. Low Level Design (LLD)<br />In this phase, HLD is broken down into smaller modules/programs. LLD is used by developers.<br />SYIT 191-200<br />15<br />
  17. 17. Type of approaches and definition<br />16<br />Approaches in sdlc<br />
  18. 18. Software development methodology approaches<br />There are a number of software development approaches that have been used since the origin of information <br />Technology. These software development approaches are:<br /><ul><li> 1.Waterfall Approach : linear framework type.
  19. 19. 2.Prototyping Approach : iterative framework type
  20. 20. 3.Rapid Application Development (RAD) Approach: Iterative Framework Type</li></ul> 4.Spiral Approach : combination of linear and iterative framework type<br />
  21. 21. Waterfall Approach<br />The Waterfall model is a sequential development approach, in which development is seen as flowing steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation, testing (validation), integration, and maintenance. <br />Basic principles of the waterfall approach are:<br />Project is divided into sequential phases, with some overlap and splashback acceptable between phases.<br />Emphasis is on planning, time schedules, target dates, budgets and implementation of an entire system<br />
  22. 22. Prototyping Approach<br />Software prototyping, is the development approach of activities during software development the creation of prototypes, i.e., incomplete versions of the software program being developed.<br />Basic principles of the Prototyping Approach are:<br />Attempts to reduce inherent project risk by breaking a project into smaller segments and providing more ease-of-change during the development process.<br />A basic understanding of the fundamental business problem is necessary to avoid solving the wrong problem.<br />
  23. 23. Spiral Approach<br />
  24. 24. Spiral Approach<br />The spiral model.<br />The spiral model approach is a software development process combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down aweigh consideration of project continuation throughout the life cycle.<br />Focus is on risk assessment and on minimizing project risk by breaking a project into smaller segments and providing more ease-of-change during the development process, as well as providing the opportunity to evaluate risks <br />
  25. 25. Rapid Application Development (RAD) Approach<br />Rapid Application Development(RAD) is a software development methodology approach, which involves iterative development and the construction of prototypes. Rapid application development is a term originally used to describe a software development process introduced by James Martin in 1991. Standard systems analysis and design techniques can be fitted into this framework.<br />Basic principles:<br />Key objective is for fast development and delivery of a high quality system at a relatively low investment cost.<br />Standard systems analysis and design techniques can be fitted into this framework.<br />
  26. 26. Phases In SDLC<br />Types Of Phases<br />
  27. 27. Analysis<br />Analysis is first phase in SDLC wherein the possible outcome of the software are discussed in detail.<br />Analysis is similar to a patient visiting a doctor.Doctors always analyse their patient:observing,testing,questioning.<br />SYIT 191-200<br />24<br />
  28. 28. Analysis Phase<br />Identify problem<br />Feasibility study for new system<br />Investigate current system<br />Organisational & system goals<br />Problems / limitations identified<br />Possible solutions<br />Evaluate all data collected<br />Decision to continue<br />
  29. 29. Coding<br /><ul><li>Coding</li></ul> During this phase, source code, executables are produced to develop the final product.<br />SYIT 191-200<br />26<br />
  30. 30. Design Phase<br />Hardware / Software to be used<br />Suppliers selection<br />Program specifications<br />Screen design<br />User interface<br />Inputs<br />Outputs<br />Setting up Tests to be performed<br />General Specifications for user documentation<br />
  31. 31. Development<br />Program Development Life Cycle (PDLC) ( to be used with customised software )<br />Testing<br />
  32. 32. Development<br />Stages of the PDLC:<br />Analyse<br />Design<br />Code<br />Debug<br />Test<br />Document<br />Implement<br />Evaluate<br />
  33. 33. Development<br /> Within he development phase there are various program development methodologies:<br />RAD: Rapid Application Development<br />Prototyping<br />Waterfall model (traditional staged development)<br />Agile model (Short bursts developing functional units of the project)<br />
  34. 34. Implementation Phase<br />Hardware purchase & set up<br />System conversion<br />Testing<br />Handover of system and documentation<br />
  35. 35. Evaluation Phase<br />Determine suitable time<br />Original aims & objectives<br />Design specifications<br />Other factors eg: efficiency, effectiveness etc..<br />
  36. 36. Overview of Analysis<br /> Analysis Phase<br />
  37. 37. What is Analysis?<br />Analysis is the first phase in SDLC where the Software is Discussed Much before it is implemented. <br />SYIT 191-200<br />34<br />
  38. 38. Phases in sdlc<br />SYIT 191-200<br />35<br />
  39. 39. Question that need to be asked?<br />Is there really a problem? <br />If there is a problem, is it worth fixing? <br />Like:<br />Technical feasibility<br /> Economic feasibility <br /> Legal feasibility <br /> Operational feasibility <br /> Schedule feasibility<br />SYIT 191-200<br />36<br />
  40. 40. Analysis does not try to describe HOW the solution will work.<br />A problem analysis will describe:<br />required input (what data has to be acquired to produce the output?) <br />required output (i.e. what information is the system supposed to produce?) <br />Data and information should be described in detail. <br />SYIT 191-200<br />37<br />
  41. 41. SDLC REQUIREMENT<br />Basic Requirement In SDLC<br />
  42. 42. SDLC REQUIREMENT<br /><ul><li>Scope
  43. 43. Technical Activities
  44. 44. Management Activities
  45. 45. Installation Guidance</li></li></ul><li>Scope Requirements<br /><ul><li>-New Development
  46. 46. - Rewrites of Existing Systems
  47. 47. - Maintenance
  48. 48. - Package Selection
  49. 49. - System Conversions</li></li></ul><li>Technical Activities<br /><ul><li>-System Definition (Analysis, Design, Coding)
  50. 50. -Testing
  51. 51. - System Installation (e.g., Data Conversion, Training)
  52. 52. - Production Support (e.g., Problem Management)
  53. 53. - Evaluating Alternatives
  54. 54. - Defining Releases
  55. 55. - Reconciling Information Across Multiple Phases
  56. 56. - Reconciling To A Global View
  57. 57. - Defining The Project's Technical Strategy.</li></li></ul><li>Management Activities<br /><ul><li>- Setting Priorities
  58. 58. - Defining Objectives
  59. 59. - Planning And Estimating
  60. 60. - Tracking/Status Reporting
  61. 61. - Change Control
  62. 62. - Step Wise Commitment
  63. 63. - Cost/Benefit Analysis
  64. 64. - Risk Assessments
  65. 65. - Interacting With Users
  66. 66. - Managing Vendors
  67. 67. - Post Implementation Reviews
  68. 68. - Quality Assurance Reviews</li></li></ul><li>Installation Support Requirements<br /><ul><li>Large and complex system containing many tasks, tools and techniques.
  69. 69. That process requires training, guidance and a phased installation.</li></li></ul><li>Designing phase<br />How to Design a software<br />
  70. 70. Design phase technical activities diagram<br />SYIT 191-200<br />45<br />
  71. 71. Purpose of designing<br />To transform the data model (developed in the analysis phase) into logical and physical information structure<br />SYIT 191-200<br />46<br />
  72. 72. Design user interface standards and guidelines<br />The GUI standards and guidelines are based on the requirements for the user interface identified in the analysis phase. Standards are needed to ensure:<br />consistency of the GUI of different parts of the application or system<br />usability of the application (e.g. reducing error in using the application)<br />maintainability<br />SYIT 191-200<br />47<br />
  73. 73. Design system architecture<br />The technical architecture used by the application is described by presenting the various hardware, software and networking components, and their interfaces.<br />SYIT 191-200<br />48<br />
  74. 74. Design software components<br />The design of functionality in Web applications include e.g. <br />navigation (functionality of control buttons)<br />control of windows (moving between frames, opening and closing of pop-up windows)<br />data input (HTML forms, cgi data transfers)<br />data processing output (dynamically created HTML pages)<br />SYIT 191-200<br />49<br />
  75. 75. Conclusion<br />The structure imposed by this SDLC is specifically designed to maximize the<br /> probability of a successful software development effort.<br />SYIT 191-200<br />50<br />