Software Development Process

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Software Development Process
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Computer Programs(sometimes called software)

• Word Processor
• Spread Sheet
• Data Base
• Games
• Robotic manipulation
• Network Management
• Many other kinds of programs

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Computer Programming(software development)

• Requirements analysis
• Specification
• Software architecture
• Coding
• Compilation
• Software testing
• Documentation
• Integration
• Maintenance

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Requirements Analysis

• Customers almost always do not know what they
  want the software to do.
• incomplete requirements
• ambiguous requirements
• contradictory requirements
• Communication and teamwork is essential.
• You have to know how to do the job before you can
  program a computer to do it!
• Organizational Introspection (do we really want
  to do it the way we are doing it?)

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Requirements Analysis

• Communication and teamwork is essential to
  success.
• Programmer with Customer (User)
• Programmer with programmer
• Programmer with hardware developer

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Requirements Analysis

• You have to know how to do the job before you can
  program a computer to do it!

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Requirements Analysis

• Organizational Introspection
• Do we really want to the job the way it has
  always been done?
• What opportunity for improved efficiency is made
  possible by evolving computer technology?

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Specification

• Precisely states WHAT the system is to do but
  does not say how it will be done.
• There are symbolic schemes for precisely stating
  a specification (see Z Notation ). Far beyond
  the scope of this course.

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Software Architecture

• Will the software interface and integrate with
  hardware and other software in current use?
• Is the software flexible enough to change as the
  needs of the customer change?

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Coding

• Coding is the art of translating the program
  specifications into a form useable by a computer.
  
• Coding is the central subject of this course
  although coding is not necessarily the most
  important part of the software development
  process.

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Compilation

• Code initially is nothing more than a text file.
  This text file is not executable by itself.
• A compiler converts the text code file into an
  executable program file.
• Once compiled, the executable program file runs
  on its own without any further use of the
  compiler. Compiled programs have the .exe
  extension.

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Interpretation

• An interpreter is a computer program that reads
  the un-compiled text code file and runs it as
  though it were a compiled program.
• Until the code is processed by a compiler into an
  executable file, an interpreter is needed to run
  the code.

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Compilation vs Interpretation

• It does take time to compile a program so it
  often efficient to use an interpreter to test
  small portions of the code.
• The program will run slower under an interpreter
  than it would if complied into an executable file.

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Assembly

• A level away from machine programming.
• Commonly used to develop firmware for
  microprocessor based embedded systems.
• Involves use of mnemonics representing machine
  code.
• An assembler is a computer program that
  automatically converts text code file into an
  executable file.

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Testing

• Especially important when parts of the program
  have been coded by separate individuals or teams.

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Documentation

• Documentation describes the internal design of
  the program. This step of software development
  is often overlooked.
• Documentation facilitates software maintenance.

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Maintenance

• Could be fixing bugs that were not discovered
  during testing.
• Most "maintenance" involves modifying the program
  to meet revised specifications.