Software Development Life Cycles

Software Development Life Cycles

1. Predicitive

   • Waterfall Models
     • Advantages
       • Very easy model to follow
       • Documentation is done throughout
       • Only producing 1 version of the product
       • Anyone can pick up and run with it at any stage
     • Disadvatages
       • If the initial requirements are misunderstood then the final product would be inccorect
       • Issues may not be found until final release to client
       • Difficult to expand or adapt the product
       • Dosen't account for any developments or changes to the initial requirements
     • Basic Principals
       • Based on sequential tasks that rely on previous tasks completed first
         • 1. Requirements: Meet with client, gain list of requirements and decide some deliverables
         • 2. System Design: Use the requirements from previous phase and design the system appropriately. GUIs, Wireframes, Relationship Diagrams Flowcharts.
         • 3.Implementation: Using the design documentation and build the end product, this could be in smaller sections which are then all brought together.
         • 4. Integration and Testing: Once all individual sections are designed, begin to bring all these elements together into 1 package and test the system internally
         • 5. Deployment: Post testing release the product to the client. All bugs should have been picked up in testing(In theory)
         • 6. Maintenance: Occurs post deployment. This could be improvements/additional functionality/repairs
       • Useful for small projects
       • Each stage must be signed off before moving on
   • Prototyping
     • Advantages
       • Ongoing client reviews and testing result in picking up issues early
       • Can allow for larger products to be delivered and tested out earlier, whilst next stage of the product is been developed.
       • Customer can see the development of the product
       • Accounts for changing requirements which can be discussed and built into the next version
       • The software is signed off at each stage, so at the end of the product the clients are more likely to approve
     • Disadvantages
       • Very time consuming
       • Requires a lot of customer input and evaluation.
       • Could lead to greater costs which where not initially agreed on
       • Gives the customer more flexibility, to change their minds
     • Basic Principals
       • Based on releasing versions of the end product with limited functions in each
       • The individual versions may not reflect the end GUI
       • Some versions may be written off
       • End goals can become clearer through each version

2. Adaptive

   • Spiral
     • Basic Principals
       • Split into 4 main parts and a version is released to the client on each cycle.
       • Each version is a revision of the last after a review and testing phase.
       • Risks are identified early on and resolved before each version.
     • Advantages
       • Can account for changes to the customers requirements at each stage
       • Can give a good representation of progression for the client
       • Can be scaleable for larger projects
       • Allows for any issues to be picked up in early versions and rectified in the next
     • Disadvantages
       • Can become very complex as projects grow
       • Would likley lead to more work to do meaning higher overheads
       • Can be very time comsuming
       • Harder to manage
   • Agile
     • Basic Principals
       • The Agile model is based on the principal of taking a large project and dividing it up into smaller tasks.
       • Tasks are delegated between teams.
       • Teams each produce a small part of the program which is then added together to create a full version for client release.
       • After each release, developers will work on improving the product based on client feedback to launch a revised version
       • Each team has a focus and will carry out a sprint to get tasks complete and products turned around quickly
     • Advantages
       • Enables developers to turn software around very quickly
       • Lots of feedback and communication with client
       • Each team will specilise in area. This results in a higher quality end product
       • Any big changes can be made quickly
     • Disadvantages
       • Documentation is done by different people at various stages.
       • Requires a team of people
       • Each person needs to be specilised in their area.
       • Requires customers to review the entire product at each stage rather than small chunks.

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