CS611 Handouts by MS

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Contents

Module 02: Cost of Software Quality Module 03: Standards and Models Module 04: Engineering Process Area Module 05: Process Management Process Area Module 06: Software Requirement Engineering vs. Software Quality Engineering Module 07: Quality Assurance Basics Module 08: Software Quality Assurance & Defects Module 09: Software Testing? Module 10: Test Activities and Management Page | 3

A. Quality Engineering Basics

What is software quality? What are the characteristics of high quality software solutions? What defines quality? These are some of the subjective question in the field of Software Quality Engineering. Modern Software Systems are usually interconnections of multiple underlying software and due to lack of standardization and varied nature it’s really difficult to define quality. Software Quality Engineering involves complete software development process just to ensure that that any agreed-upon processes, standards and procedures are being followed to get desired results and there should be no cherry picking of standards

B. Roles and Responsibility

People may have different expectations related to software quality assurance based on their roles and responsibility. The stakeholders for software development are divided into two and their expectations are as follows:

C. Consumer

Consumers of a software product are further categorized into the following:

1. Users are the group which use the services acquired by the customer: The quality expectations on the side of users are as follows:

o It performs all the functions as specified in the software requirements, which fits/meets the user’s needs. o Performs all the specified functions correctly over repeated use or over a long period of time, or performs its functions reliably.

1. Customer usually acquire the Software and Services: The quality expectations on the side of consumer are as follows:

o Basic expectations of the consumer are similar to that of users with additional concentration on the cost of the software solution.

D. Producer

Producer of the software solutions includes person involved in the development, management, maintenance and service of the software product. It also includes third party software product and organizations. For producers, the expectations are as follows:

1. Their biggest concern is to fulfill their contractual obligations by producing software products that conform to product specifications.
2. Proper choice of software methodologies, languages, tools, software usability and modifiability and other factors are closely related to quality for this category of stakeholders.

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E. Off the Shelf Products

These are plug-and-play products and are usually known as Plugins. They are developed and tested independently of Software Solutions. Their main purpose is to provide reusable functionality. Off-the-shelf (OTS) software products can be defined as “software product(s) available for any user, at cost or not, and used without the need to conduct development activities”. Proper analysis should be perform while making decision regarding selection OTS as one solution does not fit all.

ISO-9126 Quality Framework

ISO-9126 is International Standard for Software Evaluation, it provides hierarchical framework for quality definition, organized into quality characteristics. There are six top-level quality characteristics that are summarized below:

F. Functionality

Functionality is the essential purpose of any product or service. The functionality characteristic allows drawing conclusions about how well software provides and performs desired functions. The functions are those that satisfy stated or implied needs. The more functions a product has, e.g. a sale order processing system, then the more complicated it becomes to define it's functionality. Continuing with the same example, the sales order system must be able to record sales, price, quantity, tax, shipping and inventory details. The software product may have multiple functions, but functionality is expressed as a totality of essential functions that the software product provides.

G. Reliability

The set of attributes related to the capability of software to maintain its level of performance under stated conditions for a stated period of time. The reliability characteristic tells the stakeholders about how effectively and efficiently a software solution maintains the level of performance if used under specified/stated conditions. Reliability can be used to evaluate the performance of whole or part of software and based on that suggest corrective measures to ensure continued software performance.

H. Usability

Usability can be defined as the ease to use any function especially from user view-point. Usability refers to the set of attributes of any software solution related to the individual assessment of different function by the stated users. The usability characteristic allows the stakeholders to conclude about how easily the solutions can be learned, understood and used. A good example to understand the concept is the revolutionary switch from Keyboard to touchscreen in 2007, and that makes Steve Jobs quote “Machines can be user Friendly too” a reality.