This document introduces three generic software process models: the waterfall model, incremental development, and reuse-oriented software engineering. The waterfall model involves separate, sequential phases from specification to development. Incremental development interleaves specification and development in iterations. Reuse-oriented engineering assembles systems from existing software components. The document also discusses the benefits, disadvantages, and applicability of each model as well as key activities in software processes like specification, design, implementation, validation, and evolution.

1. Software Processes
Elliot Attipoe
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2. Objectives
• To introduce software process model
• To introduce 3 generic software process
models
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3. The software process
• A structured set of activities required to develop a
software system
– Specification
– Design and implementation
– Validation
– Evolution
• A software process model is an abstract
representation of a process.
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4. Generic software process models
• The waterfall model
– Separate and distinct phases of specification and
development
• Incremental (Evolutionary) development
– Specification and development are interleaved
• Reuse-oriented software engineering
– The system is assembled from existing
components
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5. Waterfall model
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6. Waterfall model problems
• Inflexible partitioning of projects into distinct stages.
• Difficult to respond to changing customer
requirements.
• This model is only appropriate when requirements
are well-understood.
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7. Incremental Development
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8. Benefits compared to waterfall
• Cost of accommodating changing customer
requirements.
• Easier to get customer feedback
• Rapid delivery and deployment of useful
software to the customer.
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9. Disadvantages
• The process is invisible.
• System structure tends to degrade as new
increments are added.
• Not good for critical systems which needs a
stable framework or architecture.
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10. Applicability
• For small or medium-sized interactive
systems.
• For parts of large systems (e.g. user
interface).
• For short-lifetime systems.
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11. Reuse-oriented software
engineering
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12. Process Activities
• Software specification
• Software design and implementation
• Software validation
• Software evolution
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13. Software Specification
• The process of establishing what services are
required and the constraints on the system’s
operation and development.
• Requirements engineering process
– Feasibility study
– Requirements elicitation and analysis
– Requirement specification
– Requirement validation
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14. Requirements engineering process
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15. Software design and Implementation
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16. Software validation
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17. Software Validation
Time
Cost to fix
error
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18. Software Evolution
• Coping with change
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19. Reading Assignment
• Prototyping - pp 45
• Spiral model – pp 48
• The rational unified process - pp 50
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20. Group Assignment (Project proposal)
• Each group is to come up with any project (software product)
they think is interesting and valuable.
• The project should have some connection to real world.
• The project can be a web application, an android application or a
desktop application.
• It is your responsibility to make sure that the project can be
built, making use of the available resources and technology to
you.
• The project should be of suitable size to be completed (including
design, testing and documentation) in 7 weeks.
• Due date : 1st Oct. 2013
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