Software Quality and SCM for UGC NET JRF 2024

Software Quality and SCM

• The lecture covers software quality and software configuration management (SCM) for UGC NET Mission JRF December 2024, Software Engineering.
• The lecture includes a recap of software testing.

Topics

• Software Quality and SCM

Content

• McCall's Factors
• ISO 9126 Quality Factor
• Quality Control
• Quality Assurance
• Change Control
• Process of change control
• Software Reuse
• Software Re-engineering
• Software Reverse engineering

McCall's Quality Factors

• Introduced in 1977
• Incorporates attributes that influence software
• Categorizes software requirements into 11 factors
• Organized into three product quality factors (product operation, product revision, and product transition)

Product Operation

• Includes five software quality factors related to operation requirements
• Operational performance, convenience, ease of use, correctness
• Aids in user experience

Product Quality Factors

• Correctness: The extent to which the software meets its requirements.
• Efficiency: The amount of resources (hardware, code) needed for the software function.
• Integrity: The software's ability to prevent unauthorized access to data.
• Reliability: The software performs its intended functions without failure.
• Usability: The effort required to learn, use, and understand the software.

Product revision

• Includes three software factors for testing and maintenance
• Focuses on providing maintenance, flexibility, and testing support for the software.

Maintainability

• Effort to detect and correct errors during maintenance phase

Flexibility

• Effort required to improve an operational software program

Testability

• Effort to verify software meets specified requirements

Portability

• Effort required to transfer a program from one platform to another

Reusability

• Extent to which the program's code can be reused in other applications

Interoperability

• Effort to integrate two or more systems

ISO 9126 Quality Factors

• International standard software quality model
• Helps create a framework for assessing software
• Categorized into four different ways to address subjects of different natures

Functionality

• Key aspect of any software that ensures task completion
• Includes purpose and/or use

Reliability

• Software's ability to sustain use under varying circumstances
• Example: ATM machine operations

Usability

• Highly dependent on software's functions
• Example: ATM cash withdrawal

Efficiency

• Focuses on system resources (disk space, memory, network) used for desired functionality

Maintainability (Software Property)

• Ability to recognize and fix defects in the software
• Software should easily adapt to environmental changes

Changes to the Software (Control)

• Documentation and control processes within a controlled environment
• Ensures integrity and consistency

Quality Control

• Focuses on identifying and resolving issues after the product release
• Reactive approach: Deal with issues after they occur
• Proactive approach: Anticipate issues and take preventative measures

Quality Assurance

• Ensuring quality requirements are met before the product release
• Proactive approach: Prevent issues before they occur

Change Logs

• Document that details information about change requests in software development
• Includes project details, priority, ownership, target dates, statuses, etc.

Change Request Forms

• Form for managing decision-making regarding software changes
• Includes details like change type, benefits, resource requestors, time estimates, costs, and status

Version Control

• Revision control for managing changes to software, computer programs, documents.
• Git for version control and project management (free and open-source)

Software Reuse

• Method for creating systems from preplanned components
• Systematic component development
• Structured reuse of components in new systems
• Increases productivity
• Shortens development time
• Develops standardized software

Software Re-Engineering

• Method for increasing software maintainability
• Study and modification of an existing system to a new form
• Risk is reduced compared to new development

Reverse Engineering

• Process of understanding a software system by analyzing its structure and behavior
• Aims to analyze the software to understand its design & requirements.

Software Maintenance Types

• Corrective: Finding and fixing errors in software
• Adaptive: Modifying software to adapt to changes in its environment
• Perfective: Improving the software's functionality

Re-engineering Cost Factors

• Cost is less than developing new software
• Software quality for re-arrangement
• Tool support available for re-engineering
• Extent of required data conversion
• Availability of expert staff

Objectives of Re-Engineering

• Relating cost-cutting options for system evolution
• Relate software maintenance process
• Differentiate software and data re-engineering to explain existing problems or issues

Reverse Engineering Steps

• Collecting information about the software (design documents, etc.)
• Examining the collected information to become familiar with the system
• Extracting the program structure (structure charts)
• Recording functionality (structured languages like decision tables)
• Recording Data Flow (Data Flow Diagrams)
• Recording Control Flow (Increased levels of control structure)
• Reviewing extracted design (for consistency and correctness)
• Generating documentation (SRS, design documents, history, etc.)

Difference Between Re-Engineering and Reverse Engineering

• Re-engineering: Improve existing software, make better
• Reverse Engineering: Understand existing software's internal functioning to implement similar functionalities