Engineering and Software Development Overview

Engineering and Software Development

• Engineering is the application of science and mathematics to solve real-world problems
• It involves using scientific principles to analyze, design, and build machines, structures, and other items (bridges, tunnels, roads, vehicles, and buildings).
• An engineer is a professional who invents, analyzes, designs, builds, and tests machines, complex systems, structures, and materials to meet functional objectives, considering practicality, regulation, safety, and cost.
• Software Engineering (SE) is the systematic application of engineering approaches to the development of software.
• It involves the systematic application of scientific and technological knowledge, methods, and experience to the analysis, design, implementation, testing, deployment, and documentation of software.
• A software engineer applies the principles of software engineering to analyze, design, develop, test, deploy, maintain, and evaluate computer software.

Main Components of SE

• People: Project stakeholders
• Product: Software product with associated documents
• Project: Activities necessary to produce the product

What is a System?

• A system is a collection of elements organized for a common purpose.
• A system is a group of interacting or interrelated entities that form a unified whole.

What is an Information System?

• An information system (IS) is a formal, organizational system designed to collect, process, store, and distribute information.
• A computer information system is a system composed of people and computers that process or interpret information.

Information System Components

• Hardware: The physical layer of the information system
• Software: Set of instructions that control hardware
• Data: Raw material that an information system transforms into useful information
• Process: Business function that users perform to achieve specific results
• People: Inside/outside users who interact with an IS

Four Ps of Systems Analysis and Design

• People: Project stakeholders
• Product: Software product with associated documents
• Process: Framework within which the team carries out activities
• Project: Sequence of activities having one goal that must be completed on time and within budget.

Measures of Project Success

• The resulting information system must meet user needs
• The resulting information system must be delivered on time
• The resulting information system must be delivered within budget

Stakeholders

• System Owner: Responsible for funding, developing, operating, and maintaining the system.
• Project Manager: Experienced professional responsible for planning, monitoring, and controlling projects.
• Systems Analyst: Specialist who studies problems, opportunities, directives, and needs of an organization to determine how people, data, processes, and information technology can best accomplish improvements for the business.
• System Designer: Technical specialist who translates business requirements into technical solutions.
• System Builder: Technical specialist who constructs information systems.
• Software Tester: Individual who tests software for bugs, errors, or problems.
• System User: Customer who will use or is affected by an information system.

Software Development Life Cycle (SDLC)

• A process of creating or altering information systems, and the models and methodologies people use to develop them.

SDLC Planning Phase

• The goal is to formulate a plan to produce the target software application.
• The important output is the Software Project Management Plan (SPMP).
• Stakeholders involved are owners, managers, analysts, and users.
• Activities include developing problem statements, formulating initial product ideas, and defining a vision for the organization's goals.
• Important activities include identifying target customers and market segments, defining project scope.

SDLC Requirements Analysis Phase

• Goal: Identify user and business requirements for the target application.
• Output: Software Requirements Specification (SRS) document
• Stakeholders are owners, managers, analysts, and users.
• Activities include identifying problems, specifying actors to understand needs, generating business requirements, preparing use cases, and creating use case diagrams.

SDLC Software Design Phase

• Goal: Define how the software will be constructed to satisfy requirements.
• Output: Software Design Document (SDD).
• Activities include creating UML diagrams(Class, Component, Deployment, Object, Package, Profile, Composite Structure, Use Case, Activity, Sequence, State Machine, Communication, Interaction Overview, Timing), E-R diagrams, and data flow diagrams.

SDLC Development Phase

• Goal: Build a system that fulfills requirements and implements necessary interfaces.
• Output: Program code ready for testing.
• Stakeholders are managers, analysts, designers, builders, and users.
• Activities include implementing code, modules and interfaces, integrating components.

SDLC Testing Phase

• Goal: Test the system to meet requirements.
• Output: Tested system ready for installation
• Stakeholders include managers, analysts, designers, builders, testers, and users.
• Activities include unit, integration, regression, system, and user testing (beta and acceptance).

Software Quality

• Definition: The degree to which software satisfies its requirements
• Metrics: Defect density, Mean Time to Failure

Veri cation and Validation

• Veri cation: Checking if a product was built according to requirements and specifications.
• Validation: Checking if each complete product artifact meets specifications.

Software Quality Assurance (SQA)

• Supported by veri cation and validation.
• Activities: Inspections and reviews, software testing.

SDLC Deployment Phase

• Final phase of SDLC.
• Involves putting the product in production and making it available to end-users.
• The goal is to make the system operational in a production environment.
• Outputs: Delivered system, release/version, trained users
• Stakeholders: Managers, analysts, builders, users
• Activities: Deployment communication, training, data entry/conversion, system installation, and post-deployment review.

SDLC Maintenance Phase

• Modifying software after release to address defects, enhancements, and performance improvements.
• Goal: Support released software, fix defects, and make improvements.

Software Process Models

• Set of activities, methods, practices, deliverables, and tools stakeholders use to develop and improve information systems.
• Examples include Waterfall, Iterative, Agile, Prototyping, and Spiral.

Waterfall Process Model

• Sequential execution through each phase.
• Advantages: Simple, easy to use, phases are executed sequentially.
• Disadvantages: Requirements must be known upfront, problems are discovered late in the process, lack of parallelism, inefficient use of resources

Iterative Development Model

• Completes the system in successive iterations.
• Each iteration has analysis, design, development, and testing.

Agile Development Model

• Highly iterative process that speeds up development and efficiently responds to change.

Extreme Programming (XP)

• Agile methodology aiming for iterative and frequent small releases.
• Values: Communication, simplicity, feedback, and respect.
• Practices: Planning game, small releases, system metaphor, simple design, test-driven development, pair programming, continuous integration, and whole team.

Scrum Methodology

• Team of 3-9 people, including a Scrum Master, who work together to deliver a product increment.
• Daily Scrum Meetings: 15-minute meetings where team members share progress, plans, and obstacles.
• Sprint: 30-day cycle where teams focus on specific features (stories) from the backlog.
• Backlog: List of customer wants and needs broken down into user stories.

Software Project Management

• Process of planning, organizing, and monitoring the development of a software project.

Organization Structure

• Project-Oriented: Personnel organized around projects.
• Function-Oriented: Groups organized by function.
• Matrix-Oriented: A cross between project and function-oriented

Team Size

• Optimal team size is 3-7 people.
• N people have N(N-1) / 2 communication channels.

Project Cost Types

• Development Costs: One-time costs
• Operating Costs: Recurring costs throughout the system's lifetime

Size Estimation Techniques

• Lines of Code (LOC): Measures the physical length of the software.
• Function Point Analysis (FPA): Measures the amount of functionality based on system specifications.

Complexity Estimation

• Based on the type and size of the application.

Effort and Duration Estimation

• Task duration: Difference between planned start and completion date.
• Effort: People needed to complete a task in a certain time period.

COCOMO Type I

• The effort required to develop applications tends to increase faster than the size of the application.

Scheduling Tools

• Work Breakdown Structure (WBS)
• PERT Chart
• Gantt Chart
• Critical Path Analysis

Requirements Analysis

• Process of understanding what is wanted and needed in an application.

Classi cation of Requirements

• Business Requirements: High-level statements of goals, objectives, and needs for the project.
• Stakeholder Requirements: What end users expect from a specific solution.
• Solution Requirements: Describe the characteristics that meet user and business needs.
• Functional Requirements: Specify the functionalities and services.
• Nonfunctional Requirements: Describe the general characteristics of a satisfactory system (maintainability, performance, security, portability, compatibility, usability).

Fact-Finding Techniques

• Research
• Observation
• Prototyping
• Sampling
• Applying Questionnaires
• Conducting Interviews
• Organizing Brainstorming Meetings
• Joint Requirements Planning (JRP) Sessions

Sampling Techniques

• Random Sampling
• Systematic Sampling
• Stratified Sampling

Questionnaire Formats

• Open-Ended Format
• Closed-Ended Format

Conducting Interviews

• To collect information through face-to-face interaction.
• Types: Unstructured, Structured.

Brainstorming Meetings

• Generating ideas during group meetings.
• Joint Requirements Planning (JRP) Sessions: A technique for drawing out user requirements through joint planning sessions.

Use Case Modeling

• Modeling a system’s functions in terms of business events.
• Elements: Actors, Use Cases, Use Case Scenarios.
• Types of Actors: Primary, Supporting.

Fully Dressed Use Case

• Detailed description of a use case.
• Includes elements like: Actors, Triggers, Preconditions, Postconditions, Normal Flow, Alternate Flows.
• Example for the online shopping system.

Use Case Diagrams

• Graphical representation of interactions between a system and external systems and users.
• Components: System, boundary, use case, actor, use case relationships (Association, Include, Generalization, Extend).

Data Flow Diagram (DFD)

• Diagram (method for representing the flow of data in a process or system)

External Agent

• An outside person, entity, system, or organization interacting with the system.

Process

• Work performed by a system in response to data flows or conditions.

Data Store

• Stored data intended for later use (often a file or database).

Levels of DFD

• Context Level DFD: shows system boundaries, external entities, and major information flows.
• Level 0 DFD: represents primary individual processes.
• Level 1 DFD: represents first-level split processes and data flow.

Decision Table

• Matrix representation of logic, specifying possible conditions and resulting actions.

Example: Check Cashing Policy Statement, Inventory Reordering System

UML Diagrams

• UML Diagrams (e.g., Class, Component, Deployment, Sequence, Activity diagrams). Including Basic Symbols and notations. UML State Machine Diagram Example Including basic symbols and notations

References

• UML Diagrams
• Software Development Life Cycle
• Software Design Phases