Untitled

• UNIT-1 Introduction to Software and Software Engineering

Core Topics

• Layered Technology/software process layers
• Software Process Models
• Linear Sequential Model
• Prototyping Model
• Evolutionary Process Models
• Introduction to software process
• Generic process framework activities
• Umbrella activities

What is Software Engineering?

• Software engineering is a combination of software and engineering
• Software is a program containing instructions to provide a desired functionality
• Engineering is designing and building something for a specific purpose, finding cost-effective solutions

Types of Software

• System Software: Operating Systems, BIOS
• Middleware Software: Transaction Middleware, Database Middleware, Message oriented Middleware
• Application Software: General Purpose, Specific Purpose
• Programming Software: Assemblers, Compilers, Interpreters, Debuggers
• Driver Software: Kernel-Mode Device Drivers, User-Mode Device Drivers
• Embedded Software: Bare Metal, Embedded Real-Time Operating System (RTOS), Embedded Networking

API's and Rest API's

• API is a broader term, REST API is a specific type of API found in mobile and cloud apps
• SOAP/XML based web services require special expertise about XML parsing, which isn't easily available
• REST APIs are lightweight and simple to implement
• REST is based on HTTP, making it easy to understand and implement across platforms like iOS, Android, Windows Phone

Software Engineering

• Software engineering is the process of designing, developing, testing, and maintaining software
• It involves a disciplined approach aiming for high-quality, reliable, and maintainable software
• It includes techniques, tools, and methodologies for requirements analysis, design, testing, and maintenance

Software Process Layers

• Tools are the outermost layer
• Methods are the second layer
• Processes are the third layer
• A quality focus is the innermost layer

Quality Focus

• Defines continuous process improvement principles
• Provides integrity, ensuring security and authorized data access only
• Focuses on maintainability and usability

Process Activities

• Communication
• Planning
• Modeling
• Construction
• Deployment

Software Engineering Foundation

• Processes are the basis of software engineering
• Key to binding layers together for development
• Processes define a framework for effective software engineering
• Software processes cover all required activities, actions, and tasks for software development

Method

• During software development, the method provides instructions on how to do certain things
• Gives the information to implement the tasks which enables communication, requirement analysis, design modeling, program construction, & testing

Tools

• Software engineering tools provide a self-operating system for processes and methods
• Tools are integrated to mean information created by one tool can be used by another

Software Processes

• Software processes are activities for designing, implementing, and testing a software system
• Software development is complicated and requires more than technical knowledge
• A software process model is an abstract representation of the development

Models Define

• Tasks to be performed
• Input and output of tasks
• Pre and post conditions
• Flow and sequence of each task

Software Development Models

• Waterfall
• V-shaped
• RAD
• Prototype
• Spiral Method
• Iterative & Incremental
• Agile Development

Software Process and Software Development Lifecycle Models

• Waterfall
• V
• Incremental
• RAD
• Agile
• Iterative
• Spiral
• Prototype

Waterfall Model

• The waterfall model is a breakdown of activities in sequential linear phases
• Each phase depends on the deliverables of the previous one and corresponds to a specialization of tasks

Waterfall Model Advantages

• Each phase must be completed before the next phase
• Error can only be fixed during a specific phase

Waterfall Model Disadvantages

• Suited for smaller projects with well-defined requirements
• Not ideal for complex projects where requirements change often

V-Model

• It represents a development process similar to the waterfall model
• Demonstrates relationships between each development life cycle phase and corresponding testing phase
• Also referred to as the Verification and Validation Model

V-Model Key Points

• Software design is a top-down process
• Testing and Validation follow a bottom-up approach

V-Model Applications

• Usage includes projects with clear, documented requirements like RFPs or requests for proposals
• Suited for military, mission-critical, and projects with well-defined & clear requirements

V-Model Advantages

• Simple and easy to use
• Each phase provides specific deliverables
• Higher chance of success with earlier test plans

V-Model Disadvantages

• Similar inflexibility issues like other waterfall models
• Early prototypes for the software are not produced

Incremental Model

• The incremental build model is a software development method integrating modules until the product is done
• It involves both development and maintenance
• This model takes on elements of the waterfall and prototyping models

Incremental Advantages

• Good when requirements are known early on
• Well-suited for longer projects

Incremental Disadvantages

• Requires good planning designs
• More costly than the waterfall model, and the definitin should be complete

Iterative Model

• An iterative life cycle model focuses on an initial user feature set, progressively adds complexity, until the system is complete
• Initial planning may be limited, but enhancements evolve over time
• Includes the usage of incremental development with some overlap

Iterative Model Steps

• Feasibility Study
• Requirements Analysis and Specification
• Design
• Coding and Unit Testing
• Integration and System Testing
• Maintenance

###Iterative Model Advantages

• Efficient, versatile of managing evolving project requirements and customer needs
• Less time is spent on documentation and more on designing
• Risks are identified and addressed rapidly and every iteration can be simply handled

Iterative Model Disadvantages

• May require more resources
• Requires many changes due to imperfect requirements
• Requirement changes can cause budget issues
• Its generally unsuitable for smaller projects

Spiral Model

• Contains risks
• Delivers components in loops
• The exact number of phases required varies by the project manager

Phases Spiral Model

• Objective setting
• Risk assessment and reduction
• Development and validation
• Planning

Applications of Spiral Method

• Projects with unclear requirements, risk is high, or new product line launch

Spiral Model Advantages

• Software is produced early in the software lifecycle
• The spiral model follows the best steps for the most effective analysis and handling of risk

Spiral Model Disadvantages

• Not suitable for small projects due to its expenses
• Is more complex, and requires a highly-specific level of expertise
• Difficulty in time management, the number of phases is unknown

Model Comparisons

• Waterfall: Yes for specification of all requirements, inappropriate for long term complex projects, not costly, simple w limited customer interaction, documents as its main form of maintenance

• Spiral: Not as all are frequent for specification of all requirements, appropriate for long term complex projects, costly, intermediate in simplicity w limited customer interaction, is maintainable

• Incremental/Iterative: Not all are frequent for specification of all requirements, appropriate for long term complex projects, costly, intermediate in simplicity w high customer interaction, maintains a good record

RAD Applications

• Provides a rapid application development model proposed by IBM in the 1980s
• Uses powerful development tools and techniques
• Offers an incremental prototyping approach for end-users to give feedback

RAD (Rapid Application Development) Components

• Requirements Planning with a cycle to refine
• User Design
• Construction
• Cutover

RAD and Traditional Model

• Rapid and Quick feedback is gathered using a prototype
• The design and build follows these two steps sequentially, as a loop
• If the test is successful, the product is delivered, if not, feedback is gathered

Advantages of RAD

• Reusable components and tools help to efficiently reduce the cycle time
• Enables developers to construct quality components in less time
• Short iteration spans easily accommodate shifting consumer demand

Disadvantages of RAD

• The resources and tools must be powerful, or the project ends up lacking good function
• Close relationships between customers is a must
• Cannot be used modular, and isn't good for projects with limited funds

Prototyping

• Prototyping creates tangible forms from paper to digital
• Used if customers do not know the exact project requirements beforehand
• Defines the process of developing a working replication of a product
• Forms a basis for the final project

The Prototyping Evolution

• Consists of refining the product based on feedback
• Delivers functional operation without technical knowledge

Throwaway and EVolutionary Prototyping

• Thrown away models are not useful and take up memory in your software
• Evolutionary prototyping leads to a cycle of development

Disadvantage of Prototyping

• Can have poor documentation or customer conflicts

Evolutionary Model

• It refers to a iterative and incremental loop
• Incremetal process over time is the main action done in the model

Application of EVolutionary Model

• Software and feature set have to be redeveloped based on client feedback

Advantages of Evolutionary Model

• Users check every step and will allow product development

What is Software Engineering Framework?

• The following tasks focus on a small specific objective
• Actions define tasks to produce major results
• Includes umbrella activities