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1 . Software Development Process

1 . Software Development Process. User’s Requirements. Software System. A Process. Unified Process: Component Based Development Components for implementation Interfaces for interconnection. Software Development Process. Activities in System Development. Requirements. Analysis.

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1 . Software Development Process

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  1. 1.Software Development Process

  2. User’s Requirements Software System A Process • Unified Process: Component Based Development • Components for implementation • Interfaces for interconnection Software Development Process

  3. Activities in System Development Requirements Analysis Design Implementation Testing System

  4. Versions of a Project • Full requirements are not given at start • Full requirements are not known • Full development may take several years Start Version 1 Version 2 Version 3 ... Implementation Analysis Design Requirements System Testing

  5. Time . . . . . . Stage 1 Stage 2 Stage 3 Stage n Release Incremental Development Reasons: • Requirements are not very clear • Requirement changes in the mean time • Feedback will help “steer” the project • Feedback helps new requirements Each stage adds new functionality Save Add / Remove spokes wheel

  6. Prototyping • Illustrates the working of system • Focuses on properties requiring insight • Allows experimentation • “Seeing it” promotes opinion & clarification • Can play with it to understand system dynamics • Not a product - just a demo Rapid Prototyping : quick functioning model Build it - See it - Dump it

  7. Reuse • Put together set of available components to develop system • Components are finest level of granularity for reuse Components: • Units that provide some functionality • Powerful and useful • Well defined interfaces • Simple to find, understand & use • Wide application • Can be used to build other components Flexible to change • Alteration must be to single component / module • Cost effective

  8. Methodology Tools Process Method Architecture

  9. Architecture, Method, Process & Tool Architecture: • Types of model that can be built and characteristic of each model • What makes the components? Method: • Sequence of Steps to realize the goal • Based on the underlying architecture • Simplifies development for a given architecture

  10. Architecture, Method, Process & Tool Process: • Scaling up of the Method • Industrialization of a Method • Activities for the entire lifetime of a product • Must be specialized into other processes Tools: • Computer - aided Systems Engineering (CASE) • Provides automation for documentation • Effective to communicate • Easy to flow from one activity to another • Improves productivity

  11. Development Approach • Waterfall Method • Spiral Method • Incremental and Iterative Development Need a Mature Repeatable Development Process

  12. Waterfall Method Requirements Analysis Design Implementation &Testing Integration Maintenance

  13. Fountain Method Maintenance Integration Implementation &Testing Design Analysis Requirements Specification

  14. Spiral Method Analysis Requirements Specification Design Implementation & Unit Testing Integration

  15. Iterative and Incremental Life Cycle • Neither top-down nor bottom-up • Successive Refinement of the OO Architecture • Apply Experience & Results to next iteration Booch’s Approach: Micro Development Process (Spiral) Macro Development Process (Waterfall)

  16. Micro Development Process Represents Daily Activity of Developers Identify Classes and Objects Specify Class and Object Interfaces and Implementation Identify Class and Object Semantics Identify Class and Object Relationships

  17. Macro Development Process Controlling Framework for Micro Process Helps Assess Risk and Make Early Corrections Activities on the Scale of Weeks to Months Conceptualization Analysis Design Evolution Maintenance

  18. Function / data Methods • Treat Functions & data as being separate • Structured Analysis and Design Technique • Functions : Active, describes behavior • Data : Passive holder of information Data Data Data . . . Function Function Function . . .

  19. Function / data Methods : Problems • Difficult to maintain • Hard to handle different data format • spilled with Switch-CASE statements • Poor readability • Change to data structure results in change to several functions • Unstable - small modifications result in major changes

  20. Object - Oriented Development • Functions and data highly integrated • More understandable • More flexible to modifications • Stable - modifications are localized

  21. Object - Oriented Analysis • Activities: • Finding the objects • Organizing the objects • Describing object interaction • Defining operations on the objects • Defining the object’s internals • Obtain understanding of system based on functional requirements • Considers functional requirements & data as integrated objects

  22. OOA Activities • Finding the Objects • Nouns in problem statement • Easy to find objects • difficult to know what is relevant • Find essential objects • Organizing the Objects • Exploring similarity between classes of objects • Organizing Classes into hierarchy • Inheritance • Whole / part • Association

  23. OOA Activities continued • Object Interaction • Scenarios or use cases provide insight - which objects work together • Helps to define Object interface • Operations on Objects • Simple primitive operations based on the interface • Avoid creating complex objects • Object Implementation / Internals • Information to be held, alternate ways of storing • Number of instances of the object • Attributes may be inherited

  24. OO Design & Implementation • Analysis model Designed & Implemented • Take care of restrictive demands • memory, response time, etc. • Traceability of Objects • Create & use Components

  25. Object - Oriented Testing • Integration is not very painful • Help broadening unit testing to larger units • Integration testing comes in earlier stages • Inheritance poses a bit of challenge in testing

  26. The Unified Process Architecture Centric Use-case Driven Iterative and Incremental

  27. Use-Case Driven • Remember the User?! • What does the user want and need from the system • Use-case • interaction by the user and the system’s response • captures functional requirements • Use-case Model • All use-cases make up complete functional model • What does the system do for each user? • What do you do with it?

  28. Use-case Model Use-case Model Developers Create design & implementation model Check models for conformance Testers Test to ensure use case implementation Drives the development process

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