Software Engineering Roger s' Pressman, Ph'D

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Software EngineeringRoger s. Pressman, Ph.D

• By Saroja Nalamalapu

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Software Engineering

• 1. Layered Technology
• 2. Process Models
• 3. The Management Spectrum
• 4. Software project Management

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5.Software Quality Assurance

• SQA Conformance to explicitly stated functional
  and performance requirements, explicitly
  documented development standards, and implicit
  characteristics that are expected of all
  professionally developed software.

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factors

• McCall and Cavano defined a set of quality
  factors that were a first step towards the
  development of metrics for software quality.
  These factors assessed software from 3 distinct
  point of views (1) product operation (using it)
  (2) product revision (changing it) (3) product
  transition (modifying it to work in a different
  environment, i.e. porting)

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factors

• These factors include correctness, Reliability,
  Efficiency, Integrity, Usability,
  Maintainability, Flexibility, Testability,
  Portability, Reusability, Interoperability .
• Invariant in past 20 years.

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Specification and design

• SQA begins with a set of technical methods and
  tools that help the analyst to achieve a high
  quality specification and the designer to develop
  a high quality design.
• Formal technical review to accomplish quality
  assurance.
• FTR-walk through or an inspection.

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Software testing

• Combines multi-step strategy with a series of
  test case design methods that help ensure
  effective error detection.
• Even testing is not effective. So use FTRs
• The major threat to software quality comes from
  changes.
• Measurement Software metrics must be colleced.

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6. Software Configuration Management

• The art of coordinating software development to
  minimize.. Confusion
• It is an art of identifying, organizing and
  controlling modifications
• Goal Maximize productivity
• SCM activities are developed to 1)Identify the
  change 2)control change 3)ensure that the
  change is implemented 4)report change to others

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7.The Technical Spectrum

• In software problem analysis- design and testing
  slowly evolved.And at the same time to make the
  software engineering tasks more systematic,
  methods were developed.
• Some methods stood the test of time.

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Software Engineering methods-The Landscape

• Different methods to achieve activities
• 3 different regions ---Conventional software
  engineering methods, Object oriented approaches,
  formal methods.
• Single objective to create high quality SW
• Any method, if properly applied within a context
  of a solid set of sw engineering principles, will
  lead to higher quality sw than an undisciplined
  approach.

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Problem Definition

• Customer communication
• Basic requirements, then req. analysis.
• Analysis Principles
• 1.The data domain of problem must be modeled
  (data objects)
• 2.The functional domain of the problem must be
  modeled (modeled as hierarchy, services to
  classes within the system, or a set of
  mathematical expressions.

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Analysis Principles cont.

• 3. The behavior of the system must be
  represented (externally observable states of
  operations and how transform occurs)
• 4. Models of data, function and behavior must be
  partitioned (As the problem definition
  progresses, detail is refined and abstraction is
  reduced partitioning)
• 5. The overriding trend in analysis is from
  essence toward implementation (Implementation
  leads from analysis toward design)

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Analysis Methods

• Beyond the scope
• Similarities among different methods and regions
  data objects and relationships,
• how functions operate on data, behavior at
  system level at more localized level,
  partitioning approach that leads to more
  detailed, foundation at which design begins

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Design

• Set of basic principles and a pyramid of modeling
  methods that provide the necessary framework for
  getting it right
• Design principles1. Data and the algorithms that
  manipulate data should be created as set of
  interrelated abstractions.
• 2.The internal design detail of data structures
  and algorithms should be hidden from other sw
  components

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Design principles cont.

• 3. Models should exhibit independence
  Effective modularity, i.e. independent models are
  easier to develop
• 4. Algorithms should be designed using a
  constrained set of logical constructs
  Structured programming

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Design Pyramid

• Data design translates the data model created
  during the analysis into DS
• Architectural design differs in intent depending
  upon the designers view point
• Conventional design creates hierarchical sw
  architectures
• OOD views architecture as message network that
  enables objects to communicate

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Design Pyramid cont.

• Interface design creates implementation models
  for human- computer interface
• Procedural design is conducted as algorithms are
  created to implement the processing requirements
  of program components

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Program construction

• 4th generation techniques, graphical programming
  methods, component-based sw construction
• The challenges that face can only be solved
  through better approaches to analysis and design
  , more comprehensive SQA techniques, more
  effective and efficient testing

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Software Testing

• Testing is the process of executing a program
  with the intent of finding an error
• Good test case high probability of finding an
  as-yet-discovered error
• Successful test uncovers an as-yet-discovered
  error
• Testing can not show the absence of defects, it
  can only show that the sw defects are present

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Strategy

• Characteristics of SW testing strategies
• 1) Testing begins at module level
• 2) Different testing techniques are required
  at different points of time
• 3) Testing is conducted by developer of SW and
  an independent test group
• 4) Testing and debugging are different
  activities.

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Tactics

• Any engineered product can be tested in 2 ways
• 1)knowing the specified function that a product
  has been designed to perform (Black-box testing)
  
• 2) knowing the internal workings of the product
  (white-box testing)

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Reuse

• To build faster software
• Components must be demonstrably defect free

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Reengineering

• SW plant must be rebuilt and that demands a
  reengineering strategy
• Takes time and money
• Paradigm for reengineering inventory analysis,
  document restructuring, code restructuring, data
  restructuring, reverse engineering (examine
  software internals to determine how the system
  has been constructed), forward engineering (
  rebuild the applications with modern SW pracices
  and principles)

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Retooling

• New generation of SW tools to meet the
  expectations
• They should emphasize Reuse and Reengineering

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Thank you.