Software Development Life Cycle

Software Development Life Cycle

1. Software Development Life Cycle model

   • Requirements-gathering
     • Design
       • Implementation
         • Testing
   • WA T E R F A L L L I F E C Y C L E MOD E L
     • The Waterfall model is characterized by a series of steps that must be completed in a linear, sequential order
     • Disadvantages of the Waterfall model
       • If requirements change or are added, the project must start over from the beginning
         • its usefulness is limited
           • is inappropriate for complex projects
             • It should not be used for developing object-oriented software, for long-term or ongoing projects, or for projects in which requirements are unknown or subject to change.
     • Advantages of the Waterfall model
       • the Waterfall model is simple and easy to use
         • Is appropriate for small development projects in which the requirements are well understood
           • Each phase has a specific purpose
   • INCREMENTAL LIFE CYCLE MODEL
     • The Incremental life cycle model builds an iterative approach into the Waterfall model
       • Requirement, design, implementation and testing phases are completed for each iteration.
     • Disadvantages of the Incremental model
       • the Incremental model exhibits some rigidity in that phases cannot be overlapped.
         • but it may be inappropriate for large, longterm projects.
           • the Incremental model may incur errors in early iterations.
     • Advantages of the Incremental model
       • generates a working prototype early in the development process.
         • flexible when adding or changing requirements
           • This model is also easier to test and debug because testing is performed incrementally during each iteration
             • The Incremental model is an effective tool for managing risk
   • SPIRAL LIFE CYCLE MODEL
     • The Spiral life cycle model is similar to the Incremental model but incorporates risk analysis. It is divided into four phases: planning, risk analysis, engineering, and evaluation.
     • Advantages of the Spiral model
       • The focus on risk avoidance makes the Spiral model ideal for large-scale and missioncritical products
         • the customer is given many opportunities to evaluate the software and plenty of time to ease into adoption of the software
     • Disadvantages of the Spiral model
       • The Spiral model is inappropriate for use in small and medium-scale projects that are not mission-critical.
         • The Spiral model can cost considerably more to implement than other life cycle models.
   • V-SHAPED LIFE CYCL
     • the V-Shaped life cycle model provides a sequential path of discrete phases that must each be completed before development proceeds to the next phase
     • Advantages of the V-Shaped model
       • is relatively simple and easy to use.
         • is appropriate for small development projects in which requirements are well understood
     • Disadvantages of the V-Shaped model
       • The rigidity of the V-Shaped model makes it inappropriate for most projects
         • all requirements must be stated at the beginning of the project,
           • All software development occurs in a single phase
             • the V-Shaped model is inappropriate for complex projects.

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