Software Design and Development

Software Design

• Software Design transforms user requirements into a suitable form, facilitating programmer coding and implementation
• During the design phase, a design document is created based on customer requirements outlined in the SRS (Software Requirements Specification) document
• The software design phase transforms the SRS document into a design document

Software Development Terminologies

• Software includes instructions or programs for computers, independent of hardware, and makes computers programmable
• System software provides core functions like OS, disk, and hardware management
• Programming software gives programmers tools like text editors, compilers and debuggers
• Application software helps users with tasks, such as office suites, data management, media players, web and mobile apps
• Embedded systems software controls telecommunications networks, cars, industrial robots, and connects to the IoT
• Programmers, or coders, write source code for computers and interpret instructions from developers/engineers
• Software engineers use engineering principles to build software and systems, devising general solutions to problems
• Software developers creatively mastermind computer programs and can be application or systems-focused

Software Developers

• Applications software developers design computer or mobile apps focused on consumers
• Systems software developers focus on operating systems-level software and enterprise solutions

Software Development

• Software Development involves building software in successive phases in an orderly way
• Software development includes writing code and preparing requirements and objectives
• The design phase and confirmation all contribute to the final objectives of the software

Systems Development Life Cycle (SDLC)

• Software development is a collective process included in creating software programs, within the SDLC
• SDLC methodologies support software design to meet business needs, development as per design, and deployment
• SDLC supports maintenance, based on project needs

SDLC Phases

• The Typical phases include
• Problem identification and planning
• Feasibility study
• Requirements analysis
• Software design
• Programming (Development or coding)
• Testing
• Software deployment
• Maintenance

Problem Identification and Planning

• Problem identification aims to describe problems and challenges, preventing the current system from achieving organizational goals
• Problem identification provides intervention and generates a broad range of intervention/options
• These problems must be linked to the stated objectives
• Problem identification considers challenges, constraints, and opportunities preventing goals from being achieved
• Problem assessment follows problem identification, assessing the scale and impact of the problem Problem assessment involves checking the scale and extent of the problem, looking at the cause and effect on project goals
• Problem prioritization allocates precedence to the identified problems, determining which problems should be tackled first
• This should also result in problem statements which describes the problem an organization faces
• Planning guides the development team through execution
• Plans should manage time, cost, quality, change, risk, and issues for the development team
• Planning includes
• Resource allocation
• Capacity planning
• Project scheduling
• Cost estimation
• Provisioning

Feasibility Study

• Feasibility Study are preliminary study to assess a project feasibility
• A feasibility study determines if the proposed solution is practical and workable in software
• Resource availability, estimation for software development, software benefits and cost is all considered in this study
• Objectives include
• Checking organizational requirements
• Checking implementations
• Checking integrations

Types of Feasibility

• Technical Feasibility
• Operational Feasibility
• Economic Feasibility
• Scheduling Feasibility
• Legal Feasibility
• Technical Feasibility considerations include technology available or if resources are needed such as programmers, testers & debuggers
  • Economic feasibility a cost-benefit analysis used for evaluating costs and benefits of a system
• Factors such as total cost, expenses are considered to determine if a venture will be profitable
• Operational feasibility checks problem resolution in the user's environment with existing and proposed systems
• The study examines the needs and the maintenance after implementation

Feasibility Report

• Feasibility report is prepared after a study and should recommend to continue or not
• The report can include additional requirements based on updates in scope, budget, and schedule

Requirements Analysis

• Requirements Analysis is a detailed statement of information needs, defining stakeholders
• Analysis includes who needs data, when do they need it, where and how the person receives that info
• Faulty requirements analysis causes system failure and development costs
• This stage includes a study of an organizations business needs
• The Major functions and analysis identifies critical processes and data entities
• Processes include business inputs, outputs and reports
• Each definition is termed a requirement with its own unique ID with a title and textual description

Elements of Requirements Analysis

• Requirements elicitation identifies and obtains system requirements from users, customers, and stakeholders
• Validation ensures that requirements represent the actual needs of stakeholders
• Raw requirements are discussed with the stakeholders to ensure the software development team is working in the right direction
• Verification confirms project requirements should be "Concise", "Traceable", "Organized", "Verifiable" and "Conformant to standards"
• Analysis in software engineering encompassing needs determination, considering conflicting stakeholder requirements
• A gap analysis should also be performed

Software Requirements Specification (SRS)

• SRS specification documents capture all software specifications
• The Document gives a description of how a system behavior functions during implementation
• Use case helps define all user interactions with the software
• SRS has non-functional requirements, imposing constraints for design and implementation
• Performance engineering requirements or quality standards help to address non-functional requirements