General introduction to quality and evaluation of projects

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IntroductionQuality Assurance (QA): standards

Quality PlanningQuality ControlProduct qualityProcess quality

Introduction to software quality evaluation

Master on Free Software

Felipe Ortega, Daniel Izquierdo, Pedro Coca

[email protected]/Libresoft

19 de noviembre de 2010

Felipe Ortega, Daniel Izquierdo, Pedro Coca Introduction to software quality evaluation

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(cc) 2010 Felipe Ortega, Daniel Izquierdo, Pedro Coca.Some rights reserved. This document is distributed under the Creative

Commons Attribution-ShareAlike 3.0 licence, available inhttp://creativecommons.org/licenses/by-sa/3.0/


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Index

1 Introduction

2 Quality Assurance (QA): standards

3 Quality Planning

4 Quality Control

5 Product quality

6 Process quality


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What is software quality?

Complex concept, different from quality in manufacturing.

Product developed to meet its specification.But it is difficult to write good software specification.

Maintainability, reusability, modularity, security, etc. areusually not included (but required).

Quality is linked to meeting end-user expectations(subjective).


I d i

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Factors that may improve quality

OOP, CASE support.

Standards (development and organizational). But bureaucracyis not enough.

Quality culture: experience, best practices, management.


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Main areas of software quality in large projects

Quality assurance: Defining framework for organizationalquality.

Quality planning: Selecting elements from the framework,adapted to a particular project.

Quality control: Checking that development teams adhere tothe plan.

For many community FLOSS projects, none of the above aredefined.

Problems for companies with this methods in place tointegrate community FLOSS.


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Process and product quality

In traditional manufacturing, process quality is tightly linkedto final product quality.

But software involves design, creativity. Subject to pastexperience and team skills.

Difficult to measure some aspects: maintainability, reusability,etc.

Obscure links between changes in process and softwareproduct quality.

Blind application of process quaility is not good for allsituations.


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Index

1 Introduction


3 Quality Planning

4 Quality Control

5 Product quality

6 Process quality


Introduction

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Quality assurance overview


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Role of software development standards

Try to convey best practices in software development.Offer required framework for QA.

Many examples: US DoD, ANSI, IEEE, BSI, NATO, etc.

Engineers usually reluctant to adopt standards (bureaucracy).


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Quality Assurance (QA): standardsQuality Planning

Quality ControlProduct qualityProcess quality

ISO 9000

International body of standards for quality in any industry.

ISO 9001 is the most extended version.

Quality in process, development and maintenance of anyproduct.Mainly concerned about high level procedures.Forces definition of specific metrics to measure quality.Involves periodic reviews to maintain ISO 9001 label award.

Involve definition of documentation templates, anddocumenting all processes.

Does not ensure that standarized process reflects bestpractices in the field.


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Documentation standards

3 different categories:

Documentation process standards: Establish good processfor document production.

Documentation standards: Define structure andpresentation of documents.

Document interoperability standards: Compatibilitybetween document formats.


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Some examples

Document identification: Unique names, easy tracking andidentification.

Document structure: Homogeneous structure for docs of similar character.

Document presentation: Customized layout and “look and

feel” (design and presentation).

Document update: Tracking changes/updates/reviews.


IntroductionQ (Q )

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Index

1 Introduction


3 Quality Planning

4 Quality Control

5 Product quality

6 Process quality


IntroductionQ li A (QA) d d

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Quality planning overview

5 different aspects:

Product overview: Description, target market, user

expectations.Product plan: Releases, updates, support, distribution, etc.

Process description: Product development and management.

Quality goals: Including identification of quality attributes to

be tracked.Risks and risk management: Risks affecting quality andcorrective actions.


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Software quality attributes


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3 components:

Quality reviews: Periodic checks of conformity with qualitystandards define in the project.

Automated assessment: Collecting quality informationautomatically (product and process).

Quality metrics: Measure different quality aspects as aninput for assessment.


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Software measurement and metrics

Sofware metric : Measurement linked to a software system,process or related documentation.

Examples: SLOC, complexity, coupling, connascence, etc.

Usually, the main problem is how to define meaningfulmetrics.

We can measure many different aspects and elements.But do they describe the quality aspect we want to track?

2 types: Control metrics (process) and predictor metrics(product).

Key application: predicting possible problems for proactivemanagement and control.



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Q y (Q )Quality Planning


Measurement procedure



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( )Quality Planning


Index

1 Introduction


3 Quality Planning

4 Quality Control

5 Product quality

6 Process quality


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Q li Pl i




Product metrics

Static metrics:

Fan-in/Fan-out : Number of functions or methods that callsome other function or method (complexity, connascence).

Length of code : Size of program. SLOC (LOC or LLOC).Cyclomatic complexity : Metric for control complexity of software.Length of identifiers : Average length of identifiers used in aprogram. Supposedly, the longer the ID, the better forreadability and maintenance of code.Depth of conditional nesting : Deeply nested statements areharder to be grasped.Fog index : Average length of words and sentences indocuments.



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Product metrics

Dynamic metrics:

Depth of inheritance tree : Number of discrete levels in the treeof classes (OOP). The deeper the tree, the more complex the

desgin.Method fan-in/fan-out : Distinction between origin of calls toother methods (from object or from external methods).Weighted methods per class : Number of methods included in aclass, weighted complexity of every method. Too complex

classes are difficult as for understanding and maintenance.Number of overriding operations : Operations overridden insub-classes. The higher this number, the less appropriate maybe the super-class.



Quality Planning

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Metrics assessment

It is not enough to collect different metrics. We need to inferassessments and conclusions from these results.

Most of times, human interpretation of results is needed.

Value ranges drawn from multiple case examples may serve asguidelines.

Usually, supported through integrated assessment frameworks(Business Intelligence).

Organization of measurement areas and lists of metrics.

Automated production of reports summarizing results.Support for elaboration of assessment reports and executivesummaries.Other buit-in functionalities: data mining, data warehouse,statistical tools, etc.


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Quality Planning




Process improvement

Quality frameworks focused on improving the process, ratherthan just describing it.

3 stages:1 Process measurement : Compilation of metrics and indicators

related to software process (development and management).2 Process analysis : Producing meaningful assessment from

results, identifying or anticipating problems that must be

corrected.3 Process change : Alter problematic elements or practices to

align the process to the quality goals of the project.



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Q y gQuality ControlProduct qualityProcess quality

Link between process and product

Humphrey, in his book about process management (1988),states that the same techniques applied to any kind of industry are valid for sofware processes.

However, a number of caveats are present in sofware projects.

The design phase plays a key role in the whole process andresults.Skills and experience of team leaders and experts affect qualityof results.Different projects may need different methodologies andapproaches.Great influence of 3 variables: cost, time frame and schedule.



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y gQuality ControlProduct qualityProcess quality

Process metrics

Process metrics should be aimed to facilitate process

improvement.3 types:

Time to complete the process.Resources required to carry on the process.Number of occurrences of a particular event to be monitored.

The key question is to identify what we need to measure.



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The GQM methodology

Frequently applied to develop customized process qualityframeworks.

Goal-oriented, top-down methodology to measure quality of software processes and products.

First developed at University of Maryland (1984) incollaboration with NASA.

Hierarchical structure composed by 3 kinds of elements: goals,questions and metrics.


IntroductionQuality Assurance (QA): standardsQuality Planning

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GQM Hierarchy


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IntroductionQuality Assurance (QA): standardsQuality Planning

Quality Control




References

Humphrey, W. S. Characterizing the software process . IEEESoftware, 5(2), 73-79. 1988.

Ian Sommerville, Software Engineering , 8th Edition. AddisonWesley, 2006.

Hans van Vliet, Software Engineering: Principles and Practice ,3rd Edition. Wiley, 2008.

V. R. Basili, Quantitative Evaluation of Software Engineering Methodology , Proceedings of the First Pan Pacific ComputerConference, Melbourne, Australia, Vol. 1 pp. 379-398, 1985.


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General introduction to quality and evaluation of projects