CEN5011 Software Engineering

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CEN5011 Software Engineering

• Dr. Yi Deng
• ECS359, [phone]
• deng_at_cs.fiu.edu

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Bottom Lines of Software Project

• COST, TIME, QUALITY
• not necessarily in that order

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Unified Process

• A software development process - A set of
  activities needed to transform a user's
  requirements into a software system
• What constitutes a software system? The CODE?
• Also a generic process framework that can be
  specialized to different types of
• Application problems,
• Application areas,
• Organizations
• Project sizes
• Uses UML
• Relationship between design language, method and
  process
• UML an integral part of UP

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Unified Process - contd

• Is Use-Case driven
• Use-Case - a piece of functionality in the system
  that is visible (or usable) to a user (not
  necessarily human user)
• All use-cases made up the Use-Case Model, which
  replaces traditional functional specification.
• Use-case model represents functional
  specification of the system FOR EACH USER - has
  important implications
• Not only for requirement specification, but also
  drives design, implementation, testing, i.e.
  development process

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Unified Process - contd

• Is Architecture-Centric
• What is architecture?
• A view of the whole design with the important
  characteristics made more visible by leaving
  details aside
• Every product has both FUNCTION and FORM these
  two cases must be balanced for a success product
• Use-case corresponds to function, architecture to
  form
• Relationship and interplay of use-case and
  architecture

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Unified Process - contd

• Is Iterative and Incremental
• Issues of complexity and evolution
• Issue of Risks
• Issues of changing requirements, platforms, and
  technology
• Controlled (planned) iteration vs. random
  iteration

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Lifecycle of Unified Process

• Is a cycle with four phases and their iterations
  (Fig. 1.3)
• Inception - seed idea of development is being
  matured and to warrant entering the elaboration
  phase. Use-case model defined
• Elaboration - architecture is defined
• Construction
• Transition - software is turned into the hands of
  the user community

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Four Phases of Unified Process
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Lifecycle of Unified Process - contd

• Each cycle results in a new release - a new
  product
• What's in a product
• Requirements, use cases, non-functional
  requirements, test cases, executable code, etc.
• A product needs to meet the needs of all
  important stakeholders, who needs different
  elements of a product (Fig. 1.4)
• Traceability between different models

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Products of Stakeholders
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Lifecycle of Unified Process - contd

• Phases within a cycle
• Phase terminates by a milestone, the availability
  of a set of artifacts
• Purpose of milestone - evaluation of process and
  make critical decisions before work can proceed
  to the next phase.
• Concept of software baseline
• Typical iterations of workflow in a cycle (Fig
  1.5)

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Process Workflow
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Key Elements of Software Development

• People - stakeholders
• Project - specialization of process
• Process - set of organized developed activities,
  template for project
• Product - outcome of project
• Tools - process automation

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Key Elements of Development
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People

• Factors that affect the effectiveness of people
• Development process affect people
• Project feasibility
• Risk management
• Team structure
• Project schedule
• Project understandability
• Sense of accomplishment

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Projects Make the Product

• A project is a sequence of changes
• A project is a series of iterations
• A project follows an organization pattern
• for people
• for planning
• for management

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Product Is More Than Code

• What is a software system? (fig. 2.3)
• Code
• Requirements, tests, sales, production,
  installation, operation,
• Different stakeholders sees different parts of
  the system
• A system has a collection of MODELS
• What is a model?
• An abstraction of a system
• A self-contained view of the system
• The system is in the eye of beholders (or
  stakeholders)
• System development is a process of modeling
  building
• Key what models to build and what relationship
  holds between models

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Multiple Facets of System
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Process Directs Projects

• Software development process
• Complete set of activities needed to transform
  users requirements into a consistent set of
  artifacts that represents a software product and,
  later, to transform changes in those requirements
  into a new, consistent set of artifacts
• A process is a template
• In other works, a process is a definition of
  activities, not their execution
• Process needs to be instantiated or specialized
  for individual projects
• Should cover entire software lifecycle

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Specializing Process

• No universally applicable process
• Why?
• Organizational factors structure, culture,
  project organization management, competence
  skill levels, prior experience, etc.
• Domain factors application domain, e.g. mission
  critical v.s. word processor, real-time v.s.
  batch processing, user community, market
  competition, etc.
• Lifecycle factors time to market, expected life
  span, planned future releases, etc.
• Technological factors programming languages,
  development tools, databases, middleware,
  communication distribution, etc.
• Bottom line general process needs to be
  specialized

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Why Process?

• Bottom line software development is a complex,
  risky, expensive and people-intensive venture
• Mutual understanding of roles, responsibilities,
  dependence, communication and coordination among
  developers and customers
• Orderly development
• Improved quality and predictivity of software
• Standardized training
• Repeat-ability of successful projects and
  continuous organizational improvement
• Improved productivity?

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Tools

• Essential to modern, complex development
• Tools impact process
• Formalized development process involves large
  amount of information and coordination
• Automation is essential
• e.g. software configuration management tools
• Process drive tools
• Process specifies the tool functionality
• Judging feasibility of tools in terms of their
  support to particular process
• Balance process and tools
• Process drives tool development, tool guides
  process