The relationship of software engineering to other area of computer science

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The relationship of software engineering to
other area of computer science
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• Programming language
• Central tools used in software development
• Having influenced how well we can achieve our
  software engineering goals

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• Operating systems
• Software should usually run on a specific
  operating system
• Need to consider if the software can work well
  with a specific operating system

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• Database
• Databases allow applications to be written that
  use data without worrying about the underlying
  representation of the data
• Allow database systems to be used as components
  of large software systems

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• Artificial intelligence
• Some researchers have been trying to apply
  artificial-intelligence techniques to improve
  software engineering

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The software life cycle

• Software is said to have a life cycle composed of
  several phases.
• waterfall model - the process structures the
  activities as a linear cascade of phases, in
  which the output of one phase flows as the input
  to the next one. Each phase has well-defined
  starting and ending points, with clearly
  identifiable deliverables to the next phase

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Phases of waterfall life cycle model

• Requirements analysis and specification
• Usually the first phase of a large-scale
  software development project
• Purpose of this phase is to identify and
  document the exact requirements of the system

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• System design and specification
• Software engineers design a software system to
  meet requirements.

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• Coding and module testing
• The engineer produces the actual code that will
  be delivered to the customer as the running
  system
• Individual modules developed in the coding
  phase are tested before being delivered to the
  next phase

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• Integration and system testing
• All the modules having been developed before
  and tested individually are put
  together-integrated-in this phase and are tested
  as a whole system

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• Delivery and maintenance
• Once the system passes all the tests, it is
  delivered to the customer and enters the
  maintenance phase. All modifications made to the
  system after the initial delivery are usually
  attributed to this phase

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Definition of software production process

• Software production process
• The process we follow to build, deliver, deploy
  and evolve the software product, from the
  inception of an idea all the way to the delivery
  and final retirement of the system.

Satisfy customers expectations by delivering
quality products on time.
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• Software can be decomposed into a number of
  specific activities
• Feasibility study
• Performed before the production process actually
  starts, to support the decision of weather a new
  development should be started.
• Its goal is to provide a feasibility study
  document, which represents different scenarios
  and alternative solutions.
• The feasibility study document should contain
• A definition of problem
• Alternative solutions and their expected benefits
  
• Required resources, costs, and delivery dates in
  each proposed alternative solution

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• Designing
• Design is the activity through which software
  engineer structure the application at different
  levels of detail.
• The result is a design specification document,
  which contains a description of the software
  architecture, including
• The system in terms of its components
• Their interfaces,
• Their interconnections

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• Delivery, deployment, and maintenance
• Delivery
• Distributed among a selected group of customers
  prior to its official release, also called beta
  testing
• Deployment
• It defines the physical run-time architecture
• Maintenance
• A set of activities performed to modify the
  system after it is delivered to the customer

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PROJECT SIZE CATEGORIES
CATEGORY NUMBER OF PROGRAMMERS DURATION PRODUCT SIZE
Trivial 1 1-4 weeks 500
Small 1 1-6 months 1K to 2K
Medium 2 to 5 1-2 years 5k to 50k
Large 5 to 20 2-3 years 50k to 100k
Very Large 100 to 1000 4-5 years 1 M
Extremely Large 2000 - 5000 5 - 10 years 1M to 10M
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Trivial PROJECTS

• 1 programmer working perhaps, part time.
• Packaged in 10 to 20 sub routines.
• Doesnt need a formal analysis.
• Conflict
• If personal software intended for personal use
  became a software product.

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SMALL PEOJECTS

• 1 programmer
• packaged perhaps in 25 to 50 routines
• Small programs have no interaction at all.
• Client interaction.
• Do have standards.
• Development Notation
• Documentation
• Reviews

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MEDIUM PROJECTS

• 2 to 5 programmers
• 250 to 1000 subroutines
• Have interactions with other programs!
• Do also have client and developer interaction.
• Advantage
• has a vastly improved product quality

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LARGE PROJECTS

• 5 to 20 programmers
• Has massive number of subroutines
• Applies several subsystem
• Example
• 1. Compiler
• 2. Database Package
• 3. Graphics Program
• 4. Real-time control system

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Very large project

• Requires 100 to 1000 programmers
• 1,000,000 source instructions
• HAS MASSIVE NUMBER OF SUBROUTINES and SUBSYSTEMS
  which forms a LARGE SYSTEM!
• Involves real-time processing, telecommunication
  and multitasking!
• Example
• LARGE SCALE OS, LARGE DB SYSTEM, AND MILITARY
  COMMAND CONTROL SYSTEM.

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TRIVIA

• According to Brooks
• IBM and OS/360 was developed by 5000 programmers
  over a period of 5 years and contained more that
  1,000,000 codes!

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Extremely large project

• Employs 2000 to 5000 programmers for a period of
  up to 10 years and results in 1 to 10 million
  lines of codes.
• It involves LIFE-and-DEATH processes
• Example
• air traffic control
• ballistic missile defense
• military command and control system

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The phases of WATERFALL life cycle model A.
Requirement analysis and specifications B.
System design and specifications C. Coding and
module testing D. Integration and system
testing E. Delivery and maintenance
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Analysis

• _______1. They are the activities through which
  we actually write programs using a programming
  language.
• _______ 2. In this phase, all system modules will
  be integrated together and tested as a whole.
•  
• _______ 3. In this phase, software engineers
  produced the actual code that will be delivered
  to the customer as running system.
•  
• _______ 4. Once the system has passed all the
  tests conducted, it will be delivered to the
  clients and then proceeds to the maintenance
  phase.
• _______ 5. It usually the first phase of a
  large-scale software development project.

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• _______6. In this phase, individual modules
  developed in the coding phase are tested before
  being delivered to the next phase.
•  
• _______7. All modifications made to the system
  after the initial delivery is usually attributed
  to this phase.
• _______8. In this phase, software engineers
  design the system to meet the requirements and
  specifications of the clients.
• _______ 9. This phase includes the architectural
  and detailed design of software development.
• _______ 10. The purpose of this phase is to
  identify and document the exact requirements of
  the system.
•  
•  

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Some considerations in software engineering

• A Component is a tested, special purpose software
  unit which is reusable, adaptable and portable.
  In software terms, components are also called
  component ware (CM).
• Framework is the combination of components that
  can be plugged into an application.

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• A Software interface is the program that makes it
  possible for components to interact and
  interoperate with each other.
• Eg. JAVA BEANS
• Software Entities are the processes,
  requirements, products and resources of a
  software engineering landscape.

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• Software Requirement Specification (SRS) This
  is a blueprint for the complete design of a
  software product.

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Major software Quality Factors

• Portability
• Reliability
• Efficiency
• Accuracy
• Robustness
• Correctness

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Reusability Criterion

• Portability means transfer of software from one
  system to other.
• Platform Independence means it can execute on any
  type of platform.

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Software Evolution

• A genotype provides information about a member of
  a population.
• A phenotype characterizes the behavior of a
  population member.
• Evolution pattern where why what when
  how by-whom.

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Software Life-Cycle

• This is the period of time beginning with a
  concept for a software product and ending
  whenever the software is no longer available for
  use.
• The Software life-cycle typically includes the
  following
• Requirements, Analysis, Design, construction,
  testing (Validation), installation, operation,
  maintenance, and retirement.

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Software Engineering approach

• The application of a systematic, disciplined,
  quantifiable approach to development, operation,
  and maintenance of software that is, the
  application of engineering to software.
• The specification, development, management, and
  evolution of software systems.
• A discipline whose aim is the production of
  quality software, delivered on time, within
  budget, and satisfying users' needs.
• Designing and developing high-quality software.
  Application of computer science techniques to a
  variety of problems.

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What is a CASE tool ?

• CASE stands for Computer Aided Software
  Engineering it can be used to mean any
  computer-based tool for software planning,
  development, and evolution.

What is a Function Point ?

• Function points and feature points are methods of
  estimating the "amount of functionality" required
  for a program, and are thus used to estimate
  project completion time. The basic idea involves
  counting inputs, outputs, and other features of a
  description of functionality.

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What is a BUG?

• A Fault, Failure, Mistake.

What is a Clean Room?

• 'Clean room' is a software process based on
  mathematical verification of components and
  system-level testing.

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What are the two major types of testing?

• The following are the two major groups of testing
• i) Black Box testing
• ii) White Box testing.

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Black Box testing

• Functional or black box testing is an approach to
  testing where the tests are derived from the
  program or component specification.
• The system is a black box whose behavior can only
  be determined by studying its inputs and the
  related outputs.
• Another name for this is the functional testing
  because the tester is only concentrated with the
  functionality and not the implementation of the
  software.

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White box testing

• Using white box testing methods, the software
  engineer can derive test cases that do the
  following
• Guarantee that all independent paths with in a
  module have been executive once at least.
• Exercise all logical decisions on their true and
  false sides
• Exercise all loops, data flow, conditional
  testing are working

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What are Check Points?

• Checkpoints enable you to compare the current
  behavior of your application to its expected
  behavior.
• GUI checkpoints check information about GUI
  objects. For example, you can check that a button
  is enabled or see which item is selected in a
  list.
• Database checkpoints check the data content in a
  database.
• Text checkpoints read text in GUI objects and
  in bitmaps, and enable you to check their
  contents.
• Bitmap checkpoints compare a "snapshot" of a
  window or an area in your application to an image
  captured in an earlier version.

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Levels of testing

• Unit testing
• Generally the code which is generated is
  compiled. The unit test is white box oriented and
  the steps can be conducted in parallel for
  multiple components.
• 1. The module Interface is tested to ensure that
  information properly flows into and out of the
  program unit under test.
• 2. The local data structure is examined to ensure
  that data stored temporarily maintains its
  integrity during all steps in an algorithms
  execution.
• 3. Boundary conditions are tested to ensure that
  the module operates properly at boundaries
  established to limit and restrict processing
• 4. All the statements are executed at least once
  and error handling paths are tested

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• Integration testing-
• Integration testing is a systematic technique for
  constructing the program structure .In
  integration test you have like
• Top down
• Bottom up
• Regressive
• Performance testing
• Recovery testing
• Security Testing
• Acceptance Testing

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Programming team structure

• Democratic team members participates in
  decision making.

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• Chief programmer assisted and supported by the
  team members.

Chief programmer
Back-up program consultant
Librarian
Junior Programmer
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• Hierarchical Team Structure

Senior Programmers
Project Leader
Junior Programmers
Junior Programmers
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Data bank

• CLEAN ROOM PORTABILITY
• BLACK BOX BUG
• FUNCTION POINT ROBUSTNESS
• EFFICIENCY SOFTWARE ENTITIES
• SOFTWARE REQUIREMENT SPECS.
• FRAMEWORK

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assignment

• Normalization
• All normal forms
• How to normalize many to many relation
• What is a procedure Give one example?