Software Development

Software Development

1. Systems Analysis Methods

   • Waterfall Lifecycle
     • User involved in analysis
       • Little input until evaluation
     • Not most effective
     • Suitable for small projects
       • Needing careful supervision
     • Linear sequence
       • Steps completed one at a time
         • Specific outputs lead to next step
   • Agile Methodologies
     • Development not completed in linear sequence
     • User feedback given throughout
       • Incremental changes made
       • Rapid
     • iterative process
       • Prototype built at each stage
     • Simple model
     • User requirements may change
   • Extreme Programming
     • Improve software quality
     • Responsive to customer requirements changing
     • Type of agile software development
       • Frequent releases of software
         • Short development cycles
           • Improve productivity
           • Checkpoints where new requirements adopted
     • Large projects
   • Spiral Model
     • Iterative stages
     • Requirements defined at start
       • Initial prototype
     • Each loop generates refined prototype
     • Large scale projects
   • Rapid Application Development
     • Large projects
     • Faster completion
     • Workshops and focus groups gather requirements
     • Prototyping refines system
       • Response to user feedback
     • Strict time limit for each part
     • Reuse software components

2. Aspects of Software Development

   • Analysis
     • Define requirements
   • Design
     • Data structures
     • Input/output
     • User interface
   • Programming and Testing
     • Black Box
       • Functional
       • Independent of code
       • Set of test data
         • Covers all input and outputs
     • White Box
       • Structural
       • Dependent on code logic
       • Tests each path
       • Does not detect missing functions
     • Alpha
       • Developer's testing team
       • Reveals errors and omissions
       • Checks against system requirements
     • Beta
       • Almost ready for release
       • Volunteers
         • Potential users report problems
       • Product exposed to real use
   • Implementation
     • Coding and testing carried out
     • Errors found and corrected
     • Software installed on user's system
     • More weaknesses found
   • Evaluation
     • Post-implementation review
     • Shortcomings found
     • User's share views and discuss improvements
     • Effectiveness
       • Usability
         • Maintainability

3. Writing and Following Algorithms

   • Good Algorithm Properties
     • Clear steps
       • Produce correct output for valid inputs
     • Allow invalid inputs
     • Terminate
     • Execute efficiently
       • As few steps as possible
     • Others can understand and modify
   • Internet-Related
     • Manage large data amounts stored on internet
   • Route-Finding
     • Driving vehicles
     • Transmitting data packets over networks
   • Compression
     • Compress data files
       • Transmitted
       • Held in smaller storage space
   • Encryption
     • Data cannot be read if intercepted
   • Interpreting Algorithms
     • Read comments
     • Look at variable names
     • Follow program's steps
     • Try "dry run" with test data

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