Software Development LifeCycle

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Software Development:

Software Development

Software Development Lifecycle:

Software Development Lifecycle


Analysis Determining exactly what the user requires This is the process of writing out clearly what the solution to the problem must to. Understanding the problems Identifying problems with the current system Identifying the needs of users Investigating similar systems elsewhere Investigating what input, processing and output are needed Establishing what tasks need to be completed Establishing deadlines for completion of tasks Problem specification:- must be clearly understood by client and developers.


Analysis Tools Flow charts Data flow diagrams Structure diagrams


Design This is where the programmer sets out how the problem will be solved by creating Screen Designs, Pseudo Code, Structure Diagrams and Test Plan. Pseudo Code is used as it can easily be transferred into code. Structure Diagrams are graphical representations of the program; this helps the programmer see the overall structure of the program clearly The design stage looks at how the new system will be built. Software systems can be broken down into: Input Process Output This stage looks at the design of all three. When the design is complete, a document called a design specification is created. This is shown to users for their comments. .


Design The Design Specification The hardware platform (PC, mainframe) The software (off the shelf, bespoke) The outputs (hardware, reports) The processing (sorting, searching, grouping) The inputs (data capture, input devices) Storage (devices, method) Security and backup The user interface (GUI, command line) The modular design of each program in the application The test plan Documentation including systems and operations documentation.


Implementation Writing the Source Code, The Code is then compiled in to machine code; machine code is in the same language as the computers operating system so it is made up of 0’s and 1’s. 101010 101010 1010101 101010 A Compiler generates Machine Code; however some programming languages use interpreters which turns the programmers code into machine code a line at a time. The advantages of this are that it can be executed with out being translated by the computer . Programs written, tested and documented Data loaded from old system to new system Staff trained on new system May be parallel running of both systems for a while or direct implementation or phased implementation System maintained by keeping it up-to-date, solving any problems and writing new programs when required.


T esting Testing the program so that it is fit for purpose. As soon as a system is developed it should be checked against user requirements to ensure the system does everything the user wants. Four stages System tested with data that contains no errors to see if it produces correct results. Known errors are introduced into the data to see how the system handles them Output is produced and checked Extreme data is entered to ensure range checks are included as part of validation Testing should use Exceptional Data; this is data outside the range. For example if a program was to accept number from 1 to 100, then exceptional data would be –12,101, A, * and any other data outside of the 1 to 100 range


Documentation Two types of documentation are produced: User guide: so that users can learn to use the system Technical documentation: so that the system can be maintained


Evaluation Does the system meet all user needs? Is it functioning correctly? Are any improvements needed?


Maintenance Good software will be readable; this helps code to be maintained, as it easy understood by other programmers.

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