software development

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QUOTE Buying the right computer and getting it

to work properly is no more complicated thanbuilding a nuclear reactor from wristwatch

parts in a darkened room using only your teeth.- Dave Barry, U.S. humorist



Software Detect

- an error that, if not removed, would cause a system tofall to meet the needs of its users.

Software Quality

- The degree to which the attributes of a softwareproduct enable it to meet the needs of its users.

Quality Management

- The definition, measurement, and refinement of

product quality during the development of information systems and other products.



Deliverables

- Products created during the various stages of software development.

The Importance of Software Quality

Business Information Systems

- A set of interrelated hardware, software, databases,networks, people, and procedures that collect data,

process it, and disseminate the output.



Decision Support System (DSS)

- a type of business information system used toimproved decision making.

Software Development Methodology

- A software development methodology defines theactivities in the software development process, definesindividual and group responsibilities foraccomplishing objectives, recommends specifictechniques for accomplishing the objectives, and offers

guidelines for managing the quality of the productsduring the various stages of the development cycle.



- Using an effective development methodology enables a manufacturer to produce high quality software, forecast project completionmilestones, and reduce he overall cost todevelop and support software. It also protectssoftware manufacturers from legal liability fordefective software in two ways:

- It reduces the number of software errors that

could cause damage and- makes it more difficult to prove negligence.



Software Quality Assurance (QA)

- Methods within a software development process thatare designed to guarantee reliable operation of thesoftware.

Types of Tests used in Software Development

1. Dynamic Software Testing

- The testing of software by entering test data and

then comparing the actual results to expected results.



Two Forms of Dynamic Testing

Black-box testing

- Unit testing of software that has expected input andoutput behaviors, with the inner workings unknown.

White-box testing- Unit testing of software that has expected input andoutput behaviors and whose internal workings areknown. It involves the testing of all possible logic

paths through the software unit and is done withthrough knowledge of the software’s logic.



Other Types of Software Testing

Static testing

- The use of special software (called static analyzers) tolook for suspicious patterns in programs that might

indicate a defect.

Integration testing

- Software testing that follows successful unit testing,

where the software units are combined into anintegrated sub system that undergoes rigorous testing.



System testing

- A form of software testing that follows successfulintegration testing, in which various subsystems arecombined and tested as a complete entity.

User acceptance testing- An independent test performed by trained users toensure that a system operates as expected from theirs viewpoint.



Capability Maturity Model Integration for

SoftwareCapability maturity Model Integration (CMMI)

- A model that defines five levels of software

development maturity and identifies the issues thatare most critical to software quality and processimprovement.



CMMI Maturity Levels

1. Initial

Process unpredictable, poorly controlled, andreactive.

2. Managed

Process characterized for projects and is oftenreactive.

3. DefinedProcess characterized for the organization and isproactive.



4. Quantitatively managed

Process measured and controlled.

5. OptimizingFocus is on continuous process improvement.



KEY ISSUES IN SOFTWARE

DEVELOPMENT1. Development of Safety-Critical Systems

A safety-critical systems is one whose failure

may cause injury or death to human beings.Key Element of Safety-Critical Systems

1. Risk – the probability of an undesirableevent occurring times the magnitude of the

event’s consequences if it does happen.



2. Redundancy- the provision of multiple

interchangeable components to perform singlefunction in order to cope with failures and errors.

N-Version programming- a form of redundancy that involves the execution of a series of programinstructions simultaneously by two different systems.

3. Redundancy-the probability of a component orsystem performing without failure over its productlife.



2. Quality Management Standards

The International Organizations forStandardization (ISO), founded in 1947, is a worldwide federation of national standards bodiesfrom some 100 countries. This ISO issued its 9000series of business.

These standards require organizations to developformal quality management systems that focuses onidentifying and meeting the needs, desire, andexpectations of their customers.



The ISO 9000 standards serves many industries andorganizations as a guide to quality products,services, and management. Many companies angovernment agencies specify that a company mustbe ISO 9000- certified to win a contract fromthem.



To obtain this coveted certificate, an organization

must submit to an examination by an externalassessor and fulfill the following requirements:

1. Have written procedures for everything it does.

2. Follow those procedures.

3. Prove to an auditor that it has fulfilled the firsttwo requirements. This proof can requireobservation of actual work practices andinterview with customers, suppliers, andemployees.



The various ISO 9000 series of standards addressthe following activities:

ISO 9001

Design, development, production, installation,

servicing. ISO 9002

Production, installation, servicing.

ISO 9003

Inspection and testing



ISO 9000-3The development, supply, and maintenance. ISO 9004

Quality management and quality systems. 3.

Failure mode and effects analysis (FMEA)- a reliability evaluation technique used todetermined the effect of system and equipmentfailures.- The goal of FMEA is to identify potential design and

process failure early in a project when they arerelatively easy and inexpensive to correct.

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