Software Development LifecycleThis is used by software designers - the wholedesign process can be thought of as a cycleThe stages are: Identify - Define requirements and specification Design - Plan the solution to the problem Develop - Produce the program code Test - Locate and remove any errors Evaluate - Review against program requirements 2
Identify the ScopeThe first stage of the design process is based uponanalysing the user’s requirements to determinewhat is achievable with the resources available.Resource limitations (called constraints) usuallyinvolve time and money.Prioritise the most important features and decidewhat will be included in the first version of thesoftware and what can be left out and put on the‘wish list’ for future versions.You then need to produce a formal writtenrequirements specification for the program 3
Design DocumentationRequirement Specification: Inputs are required from the user Outputs expected by the user Processing needed to provide functionality Constraints e.g. time, funds, specialist skillsScreen DesignsProgram Design: Modules and Algorithms: Structure Diagram / Flowcharts / PseudocodeData DictionaryTest Plan 4
Requirements SpecificationInputs: List of all the data that is input by the user Give specific details of the actual data, e.g. first name and last name of user Identify valid and invalid values for text and acceptable ranges for numeric dataOutputs: List of all output expected by the user Give specific details of the actual data and format, e.g. Monthly sales report which will be displayed in a bar chart, showing total sales for each product Include any help information e.g. Instructions, error messages or visual feedback 5
Requirements SpecificationProcessing: Give details of all the functions theprogram will need to have. You should break this down into each processing task e.g. validation, calculations, formatting etc. Explain what each function should do (not how – yet!) There could be many of these in your proposed systemConstraints: Identify any resource limitations It could include budget, development timescales, hardware available, training requirements, special needs of users etc. Give specific details of each, e.g. The total budget available is £50,000 6
Screen DesignsProvide a storyboard to show screens atvarious stages of the programDraw them… Count Down On paper… In Word or Visio… In Visual Studio…They must show The prompts the user will see Example input Example output 7
Process SpecificationRequirements Specification - describes WHAT thesystem must be able to do.Process Specification - provides details of HOW therequired functionality is achieved.Various techniques used to clarify procedures Flow Charts Structure Diagram Pseudocode / Structured EnglishProvides the logical design for a computer algorithmNot language specific 8
Data DictionaryThis is used to document the variables and datatypes used in your programShow the variable names, datatypes and adescription of what data the variable is going tostoreIdentify location e.g. Local or Global Remember local is better 9 9
A Data Dictionary Table with details of all important variablesVariable DataType DescriptionVAT Global Single, Constant Holds current VAT rate (17.5%)sngVATPrice Local to Single Holds price of goods Checkout inc VATintQuantity Local to Integer Number of items Checkout 10
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