SQA presenatation made by krishna ballabh gupta

Software Quality Assurance

ForSoftware Engineering

&&Architecture and Design


• What is “quality”?



• IEEE Glossary: Degree to which a system, component, or process meets (1) specified requirements, and (2) customer or user needs or expectations



• IEEE Glossary: Degree to which a system, component, or process meets (1) specified requirements, and (2) customer or user needs or expectations

• ISO: the totality of features and characteristics of a product or service that bear on its ability to satisfy specified or implied needs


• An alternate view of Quality:– is not absolute– is multidimensional, can be difficult to quantify – has aspects that are not easy to measure– assessment is subject to constraints (e.g., cost)– is about acceptable compromises– criteria are not independent, can conflict


• Quality Criteria include:– correctness – efficiency– flexibility– integrity– interoperability– maintainability– portability– reliability– reusability– testability– usability

What is Software Quality Assurance (SQA)?

• “Set of systematic activities providing evidence of the ability of the software process to produce a software product that is fit to use”– G. Schulmeyer and J. McManus, Software

Quality Handbook, Prentice Hall, 1998.

What is SQA?

• Monitoring processes and products throughout the software development lifecycle to ensure the quality of the delivered product(s)

• Monitoring the processes– Provides management with objective feedback

regarding process compliance to approved plans, procedures, standards, and analyses

• Monitoring the products– Focus on the quality of product within each phase

of the SDLC • e.g., requirements, test plan, architecture, etc.

– Objective: identify and remove defects throughout the lifecycle, as early as possible

Quality of Software developed in-house & COTS components

• SQA processes apply when integrating purchased or customer-supplied software products into the developed product

• Question. How do you determine the “quality” of COTS components?– Current research problem

Process Assessment

• Use of standards and process models has a positive impact on the quality of the software product– Disciplined, controlled development process

• Examples include:– ISO 9001

– CMM• CMU SEI, 5 levels

– SPICE • Developing a standard for software process assessment

• ISO joint committee, Europe, Australia

– IEEE 1074, IEEE 12207, …

Product Assessment

• Reviews, inspections, walkthroughs– Specialized techniques available:

• How to review/assess requirements, architecture, detailed designs, code

• …

• Testing• Simulation• Protoyping• Formal verification

– Model checking, theorem proving

Product Assessment

• Reviews, inspections, walkthroughs of Plans, reports, models, standards– Project management, quality assurance,

training, test plan(s)– Requirements, analysis, architecture, detailed

design model, test cases – Issue or problem reports– Metric reports– Traceability reports– Documentation, coding standards– …

Software Reviews

• They may include managerial reviews, acquirer-supplier reviews, technical reviews, inspections, walkthroughs, and audits.

• Inspection:– A formal evaluation technique in which an artifact (e.g., software

requirements, design, or code) is examined in detail by a person or group other than the originator

– detect faults, violations of development standards, and other problems.– review members are peers (equals) of the designer or programmer.– data is collected during inspections for later analysis and to assist in future

inspections. Note– Introduced by Fagan, 1976.– Fagan, M., “Design and Code Inspections to Reduce Errors in Program

Development”, IBM Systems Journal, 15, 3 (1976), pp. 182-211– Fagan, M., “Advances in Software Inspections”, IEEE Transactions on Software

Engineering, 12, 7(July 1986), pp. 744-751

Picture from “Inspections” presentation http://www.math.uaa.alaska.edu/~afkjm/cs470/handouts/inspections.pdf

Defect Checklists• Useful to support reviews, inspections, walkthroughs• Expertise is captured in a list format

– Less experienced people can use• Straightforward to use (each check should be clear, simple to assess/apply)

– Improve consistency of assessments

• Example architecture checklist used in undergrad./grad. courses for OO – spreadsheet in in the course materials subdirectory

• One or more architectural styles are selected.• Capabilities and interfaces are defined for subsystems.• Capabilities of and interfaces among subsystems support all of the use cases.• Concurrency defined.• Distribution defined.• Error handling defined.• Start up and shut down defined.• Data persistency defined.• Rationale for the model is provided.• Other

Verifying Formal Specifications• Formal specifications may be verified in a number of

different ways:–Syntax, typechecking

• If the notation is typed–Simulated–Model checked (e.g., SPIN)–Proven correct (e.g., HOL, PVS)

• More straightforward? Less assurance of correctness; fully automated

• Less straightforward? Higher assurance of correctness; not fully automated

More straightforward

Lessstraightforward

Problem Reporting, Tracking, and Resolving

• Describe the practices and procedures to be followed for reporting, tracking, and resolving problems– Who can report a problem?– How is it reported?– How is is tracked?– Who determines if it is a problem that going to be resolved?– How is it assigned for resolution?– How does the person indicate it has been corrected?– Who reviews it to determine if it can be closed?

• Problems can be product or process related– e.g. incorrect requirement, incomplete class definition, code

defect, ambiguous description in user documentation, process to review detailed design is not clearly defined, etc.

Metrics

• Metrics for each artifact• e.g., Requirements

– Number of requirements– Number of changes per requirement

• Called “churn” rate

– Characterization of defects• Not testable, ambiguous, inconsistent, incorrect,

incomplete redundant, infeasible, …• Major or minor defect• Phase defect detected• Cost to fix

Tools, techniques, training

• What tools?– e.g., CVS for CM, excel spreadsheet for

problem reporting/tracking, ...

• What techniques?– e.g., formal peer review for deliverables,

checklists for defect detection, ...

• What training is needed on tools, techniques?

Media Control

• Identify the media for each intermediate and deliverable artifact

• Documentation required to store the media, including the backup and restore process

• Protect computer program physical media from:– unauthorized access– inadvertent damage– degradation

Architecture Analysis Methods• Why evaluate an architecture?

http://www.slideshare.net/kevinjew/evaluating-software-architectures-presentation

• Specialized techniques available:http://www.slideshare.net/timmenzies/architecture-

tradeoff-analysis-method-presentation

SEI presentation and technical report on ATAM are in the course subdirectory