Top: 1 Software and Software Engineering

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Top 1Software and Software Engineering
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Softwares Dual Role

• Software is a product
• Produces, manages, acquires, modifies, displays,
  or transmits information
• Software is a vehicle for delivering a product
• Supports or directly provides system
  functionality
• Controls other programs (e.g., an operating
  system)
• Effects communications (e.g., networking
  software)
• Helps build other software (e.g., software tools)

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What is Software?
Software is a set of items or objects that form
a configuration that includes
programs documents data ...




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What is Software?

• software is engineered
• software doesnt wear out
• software is complex

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Software Applications

• system software
• application software
• engineering/scientific software
• product-line software
• WebApps (Web applications)
• AI software

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Legacy Software
Why must it change?

• software must be adapted to meet the needs of new
  computing environments or technology.
• software must be enhanced to implement new
  business requirements.
• software must be extended to make it
  interoperable with other more modern systems or
  databases.
• software must be re-architected to make it viable
  within a network environment.

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Software Evolution

• The Law of Continuing Change (1974) E-type
  systems must be continually adapted else they
  become progressively less satisfactory.
• The Law of Increasing Complexity (1974) As an
  E-type system evolves its complexity increases
  unless work is done to maintain or reduce it.
• The Law of Self Regulation (1974) The E-type
  system evolution process is self-regulating with
  distribution of product and process measures
  close to normal.
• The Law of Conservation of Organizational
  Stability (1980) The average effective global
  activity rate in an evolving E-type system is
  invariant over product lifetime.
• The Law of Conservation of Familiarity (1980) As
  an E-type system evolves all associated with it,
  developers, sales personnel, users, for example,
  must maintain mastery of its content and behavior
  to achieve satisfactory evolution.
• The Law of Continuing Growth (1980) The
  functional content of E-type systems must be
  continually increased to maintain user
  satisfaction over their lifetime.
• The Law of Declining Quality (1996) The quality
  of E-type systems will appear to be declining
  unless they are rigorously maintained and adapted
  to operational environment changes.
• The Feedback System Law (1996) E-type evolution
  processes constitute multi-level, multi-loop,
  multi-agent feedback systems and must be treated
  as such to achieve significant improvement over
  any reasonable base.

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Software Engineering A Layered Technology
Software Engineering
tools
methods
process model
a quality focus
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A Process Framework
Process framework Framework activities work
tasks work products milestones deliverables QA
checkpoints Umbrella Activities
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Framework Activities

• Communication
• Planning
• Modeling
• Analysis of requirements
• Design
• Construction
• Code generation
• Testing
• Deployment

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Umbrella Activities

• Formal technical reviews
• Software quality assurance
• Software configuration management
• Work product preparation and production
• Reusability management
• Measurement

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The Process ModelAdaptability

• the framework activities will always be applied
  on every project ... BUT
• the tasks (and degree of rigor) for each activity
  will vary based on
• the type of project
• common sense judgment concurrence of the project
  team

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Process Patterns

• Process patterns define a set of activities,
  actions, work tasks, work products and/or related
  behaviors
• A template is used to define a pattern
• Typical examples
• Analysis (an action)
• Requirements gathering (a process task)
• Reviewing a work product (a process task)
• Design model (a work product)

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Process Assessment

• The process should be assessed to ensure that it
  meets a set of basic process criteria that have
  been shown to be essential for a successful
  software engineering.
• The CMMI defines each process area in terms of
  specific goals and the specific practices
  required to achieve these goals.
• Specific goals establish the characteristics
  that must exist if the activities implied by a
  process area are to be effective.
• Specific practices refine a goal into a set of
  process-related activities.

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Assessment and Improvement
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Personal Software Process (PSP)

• Recommends five framework activities
• Planning
• High-level design
• High-level design review
• Development
• Postmortem
• stresses the need for each software engineer to
  identify errors early and as important, to
  understand the types of errors

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Team Software Process (TSP)

• Each project is launched using a script that
  defines the tasks to be accomplished
• Teams are self-directed
• Measurement is encouraged
• Measures are analyzed with the intent of
  improving the team process

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The Primary Goal of Any Software Process High
Quality
Remember High quality project
timeliness Why? Less rework!