Software Engineering Processes

Software Processes

• Software processes are a set of related activities involved in producing a software system.
• Fundamental software engineering activities: specification, design, implementation, validation, evolution.
• A software process model is an abstract representation of a process. It describes the process from a specific perspective.
• Software process descriptions often involve activities like data modeling, interface design, their order and sub-activities (e.g., requirements validation, testing).
• Descriptions include products (outcomes), roles (responsibilities), pre and post conditions.

Software Process Models

• Waterfall model: Plan-driven, distinct phases (requirements, design, implementation, testing, maintenance). Appropriate when requirements are well-understood.
• Incremental development: Interleaved specification, development, validation . Rapid feedback. Better for changing requirements.
• Integration and configuration: Assembling systems from components. Plan-driven or agile. Common for large systems.

Plan-driven and Agile Processes

• Plan-driven: All activities planned in advance, progress measured against the plan. Used for safety critical systems.
• Agile: Planning is incremental and continuous, easier to adapt to changing customer needs. Suitable for business systems with rapidly changing requirements.

The Waterfall Model

• Phases are: Requirements definition, System and software design, Implementation and unit testing, Integration and system testing, Operation and maintenance.
• Process activities are sequential.
• Results (documents) must be approved before moving on
• Not adaptable to changes.

Incremental Development

• Specification, development and validation are interleaved.
• Rapid feedback across activities
• Multiple releases
• Cost-effective when requirements change

Incremental Development Benefits

• Reduced cost of accommodating changes.
• Easier to get customer feedback on development work
• Early delivery of usable software.

Incremental Development Problems

• Process visibility problems.
• Structural degradation as new increments are added.
• Costs to add new features can increase.

Integration and Configuration

• Systems are integrated from existing components or commercially available systems.
• Reuse of elements allows adaptation to user needs.
• Standard approach for many systems.

Types of Reusable Software

• Stand-alone application systems (COTS).
• Collections of objects organized in frameworks.
• Web services.

Advantages and Disadvantages of Reusable Software

• Advantages: reduced costs, faster delivery, earlier deployment.
• Disadvantages: requirement compromises, loss of control over reused elements.

Process Activities

• Software processes include technical, collaborative, and managerial activities.
• Core activities (specification, development, validation, evolution) are organized differently in various models. Waterfall is sequential, incremental is interleaved.

Software Specification

• Establishing the services, constraints, and requirements of the software.
• Critical stage, mistakes affect later stages

Requirement Engineering Activities

• Elicitation and analysis: understand stakeholder needs.
• Specification: detailed requirements definition.
• Validation: checking the requirements for accuracy.

Software Design and Implementation

• Converting the specification into an executable system.
• Includes architectural design, data modeling, interface design, and component design.
• Activities are closely related and can occur simultaneously.

A General Model of the Design Process

• Inputs: platform details, requirements specification, and data descriptions.
• Activities: architectural, interface, database, and component design.

System Implementation

• Developing or configuring software based on the design. Design and implementation are often combined.
• Debugging faults and resolving them.

Software Validation

• Ensuring the system conforms to its specification and customer requirements.
• Includes verification checking, review processes, and system testing

Testing Stages

• Component testing: testing individual components.
• System testing: testing the system as a whole (interactions).
• Customer testing (Alpha/Beta testing) real-world testing.

Testing Phases in a Plan-Driven Software Process

• Testing is driven by plans.
• Independent testing teams work in parallel, deriving test plans from specifications, design and code.

Software Evolution

• Software is flexible and needs change to reflect business changes.
• Development and maintenance are a continuum. Not distinct.

Coping with Change

• Change is inevitable.
• Processes must be able to adapt to changing needs & circumstances.
• Important to anticipate and plan for change.

Reducing Rework Costs

• Anticipate change through activities like prototyping.
• Design processes that tolerate and accommodate changes easily.

Software Prototyping

• Creating an initial version for demonstrating concepts.
• Used to learn more about customer needs & explore different design choices.
• Prototypes are typically disposable.

Process Improvement Cycle

• Measure: Gather data and document what needs to be improved
• Change: Make necessary alterations/develop new strategies
• Analyze: Assess the effectiveness of the improvements & identify further areas for improvement.

Process Improvement

• Understanding existing processes, improving quality & reducing cost
• Agile methodologies focus on reducing overhead
• Maturity-based approaches use good software engineering principles

Approaches to Process Improvement

• Process Maturity Approach: Focuses on improving process & project management, enforcing good software engineering principles.
• Agile Approach: Focuses on iterative development, rapid delivery, responsiveness to changing customer needs.

Process Measurement

• Gathering data to aid decisions on where to improve.
• Data collection methods include time taken, resources used, and numbers of defects discovered.

SEI Capability Maturity Model

• Initial: Uncontrolled process
• Managed: Basic process management
• Defined: Standardized process
• Quantitatively Managed: Process measurements
• Optimizing: Continuous process monitoring

Rational Unified Process(RUP)

• Framework for software development.
• Iterative and incremental.
• Four phases: Inception, Elaboration, Construction, and Transition.
• Iterations within phases.
• Static and dynamic perspectives.

Explore the various software processes and models including the Waterfall model and Incremental development. This quiz covers key activities involved in software engineering, such as specification, design, and validation. Test your knowledge on different software process models and their applications.