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					               Software Engineering
            Methodologies (Introduction)

                              Shahbaz Pervez Chattha

Software Engineering Methodologies                         Slide 1
             Software Engineering Methodologies
Course title                                Course code
Software Engineering Methodologies
Instructor: Shahbaz Pervez Chattha          Semester
Venue                                       Credit hours: 3
Class room: 1
Instructor’s Office Number                  Visiting hours
Direct: 051-9047465                         By availability
Instructor’s email                          Mode of lecture delivery:                    Multimedia
Course TA/: Mr. Farhan Adil                 Schedule
       Software Engineering Methodologies   Fridays 3:00 – 6:00 pm   Slide 2
             Why Software Engineering?
• Software development is hard !
• Important to distinguish “easy” systems (one
  developer, one user, experimental use only) from
  “hard” systems (multiple developers, multiple users,
• Experience with “easy” systems is misleading
   – One person techniques do not scale up
• Analogy with bridge building:
    – Over a stream = easy, one person job
    – Over River Jhelum … ? (the techniques do not scale)

 Software Engineering Methodologies                  Slide 3
            Why Software Engineering ?

• The problem is complexity
• Many sources, but size is key:
    – UNIX contains 4 million lines of code
    – Windows 2000 contains 108 lines of code

    Software engineering is about managing
                this complexity.
 Software Engineering Methodologies             Slide 4
           Recommended Course Textbooks

• Sommerville I. (2001)
  Software Engineering
  6th Edition, Addison-Wesley, Harlow,
  Essex, UK

• Roger S. Pressman (2000)
  Software Engineering:
  A Practitioner's Approach,
  5th edition, McGraw-Hill, USA
  Software Engineering Methodologies     Slide 5
     Recommended Course Textbooks

• Project Management
A systems Approach to Planning, Scheduling and
  Controlling.(7th Edition)
By Harold Kerzner

 Software Engineering Methodologies        Slide 6
                                 Outline Syllabus
1.    Introduction to Software Engineering
2.    Software Processes & Process Improvement
3.    Software Design and Implementation
4.    Software verification, validation and testing
5.    Quality Assurance
6.    Configuration Management
7.    Metrics and measurement
8.    Requirements Engineering
9.    Software Project Management
10.   Risk Management
11.   WBS Estimation & Scheduling
12.   MS Project, Tools – Applications
13.   Reengineering
14.   Integration & Testing
15.   Real Time and Embedded Systems Design
16.   Software Engineering in Pakistan Industry

 Software Engineering Methodologies                   Slide 7
                                What is software?
• Computer programs and associated documentation

• Software products may be developed for a particular
  customer or may be developed for a general market
• Software products may be
   – Generic - developed to be sold to a range of different
   – Bespoke (custom) - developed for a single customer
     according to their specification
  Software Engineering Methodologies                          Slide 8
             What is software engineering?
Software engineering is an engineering discipline
  which is concerned with all aspects of software
Software engineers should
  – adopt a systematic and organised approach to their work
  – use appropriate tools and techniques depending on
       • the problem to be solved,
       • the development constraints and
       • the resources available
   Software Engineering Methodologies                Slide 9
          What is the difference between software
           engineering and computer science?

   Computer Science                               Software Engineering
                                        is concerned with

 theory                                         the practicalities of
 fundamentals                                   delivering useful software
    Computer science theories are currently
 insufficient to act as a complete underpinning
     for software engineering       
   Software Engineering Methodologies                                 Slide 10
                What is the difference between software
                 engineering and system engineering?

• System engineering is concerned with all aspects
  of computer-based systems development including
  hardware, software and process engineering

• Software engineering is part of this process

• System engineers are involved in
     system specification, architectural design,
     integration and deployment
  Software Engineering Methodologies             Slide 11
               What is a software process?

• A set of activities whose goal is the
  development or evolution of software
• Generic activities in all software processes are:
    – Specification - what the system should do and its
      development constraints
    – Development - production of the software system
    – Validation - checking that the software is what the
      customer wants
    – Evolution - changing the software in response to
      changing demands
 Software Engineering Methodologies                  Slide 12
           What is a software process model?
     A simplified representation of a software process,
          presented from a specific perspective
• Examples of process perspectives:
  Workflow perspective represents inputs, outputs and dependencies
  Data-flow perspective represents data transformation activities
  Role/action perspective represents the roles/activities of the
                          people involved in software process
• Generic process models
  – Waterfall
  – Evolutionary development
  – Formal transformation
  –Software Engineering Methodologies reusable components
      Integration from                                      Slide 13
                  What are the costs of software
• Roughly 60% of costs are development costs,
  40% are testing costs. For custom software, evolution
  costs often exceed development costs

• Costs vary depending on the type of system being
  developed and the requirements of system attributes
  such as performance and system reliability

• Distribution of costs depends on the development
  model that is used
 Software Engineering Methodologies               Slide 14
                     What are software engineering
Structured approaches to software development
which include system models, notations, rules, design
advice and process guidance
• Model descriptions                    (Descriptions of graphical
  models which should be produced)
• Rules (Constraints applied to system models)
• Recommendations (Advice on good design practice)
• Process guidance (What activities to follow)
   Software Engineering Methodologies                            Slide 15
                          What is CASE ?
                (Computer-Aided Software Engineering)

  Software systems which are intended to provide
  automated support for software process activities, such
  as requirements analysis, system modelling, debugging
  and testing

• Upper-CASE
  – Tools to support the early process
     activities of requirements and design
• Lower-CASE
  – Tools to support later activities such as
    programming, debugging and testing
   Software Engineering Methodologies              Slide 16
                  What are the attributes of good
 The software should deliver the required functionality
      and performance to the user and should be
           maintainable, dependable and usable
• Maintainability
    – Software must evolve to meet changing needs
• Dependability
    – Software must be trustworthy
• Efficiency
    – Software should not make wasteful use of system resources
• Usability
    – Software must be usable by the users for which it was designed
 Software Engineering Methodologies                          Slide 17
                        What are the key challenges
                                 facing software engineering?
  Software engineering in the 21st century faces
  three key challenges:
• Legacy systems
  – Old, valuable systems must be maintained and updated
• Heterogeneity
  – Systems are distributed and include
     a mix of hardware and software
• Delivery
  – There is increasing pressure
    for faster delivery of software
   Software Engineering Methodologies                      Slide 18
                     Professional and ethical
• Software engineering involves wider responsibilities
  than simply the application of technical skills

• Software engineers must behave in an honest and
  ethically responsible way if they are to be respected
  as professionals

• Ethical behaviour is more than
     simply upholding the law

 Software Engineering Methodologies                 Slide 19
                                     Next lecture

                  Software Processes

Software Engineering Methodologies                  Slide 20