LECTURE-2

Software Is a Product Designed by software engineers. Consists of : –Programs - that execute within a computer and provides desired functions. –Documents- describe the operation and use of the program –Data - which can be numerical, textual, pictorial, video etc.

Software - the Product Information Software Vehicle to deliver the product Software Operating System Network Software Case tools Produces Manages Acquires Modifies Displays Transforms

In today’s lecture we will learn about the product that is to be engineered. And the process (Next class) that provides a framework for the engineering technology The following questions will addressed in today’s lecture. What is computer software ? Why do we struggle to build high-quality computer-based systems? How can we categorize application domains for computer software ? What myths about software still exist? Software characteristics. Failure curve for hardware The crisis of software.

Computer software is the product that designed and built by software engineers. Software is used by virtually everyone in society. Software engineers have a moral obligation to build reliable software that does no harm to other people. Software engineers view computer software, as being made up of the programs, documents, and data required to design and build the system. Software users are only concerned with whether or not software products meet their expectations and make their tasks easier to complete. Overview

HOW SHOULD WE DEFINE SOFTWARE ? A textbook description of software might take the following form: Software is (1) instructions (computer programs) that when executed provide desired function and performance, (2) data structures that enable the programs to adequately manipulate information, and (3)documents that describe the operation and use of the programs. There is no question that other, more complete definitions could be offered. But we need more than a formal definition.

Software Software is both a product and a vehicle for developing a product. Software is engineered not manufactured. Software does not wear out, but it does deteriorate. Currently, most software is still custom- built. SOFTWARE CHARACTERISTICS

FAILURE RATE TIME “Infant mortality” “Wear out” Figure2.1:- Failure curve for hardware

FAILURE RATE TIME Figure2.2:- Idealized and actual failure curves for software Increased failure rate due to side effects Idealized curve Change Actual curve

Software application System Software Real time software Web-based software Business software Engineering and scientific software Embedded software Personal computer software Artificial intelligence software. Compilers, editors, and file management utilities,operating system components, drivers, telecommunications processors Software that monitors/analyzes/controls real- world events as they occur is called real time Payroll, accounts receivable/payable, inventory,MIS, Point of sale transaction processing Scientific area are moving away from conventional numerical algorithms. Computer- aided design, system simulation, and other interactive applications have begun to take on real time and even system software characteristic. Keypad control for microwave oven, Digital functions in an automobile such as fuel control, dashboard displays, and braking systems Word processing, spreadsheets, computer graphics, multimedia, entertainment, database management, personal and bussiness financial applications, external network. HTML,Perl, or Java and data hypertext and a variety of visual and audio formats Expert systems, Knowledge based systems, pattern recognition (image and voice),artificial neural networks, theorem proving, and game playing.

Types of Software System software – it services other programs –heavy interaction with hardware, Real-time software –data gathering component –analysis component –monitoring component Business software –largest single software area –MIS important component Engineering and scientific software –number crunching numerical algorithms

Types of Software Embedded software –resides in read-only memory of any appliances –controls products and system for consumers PC software –several hundreds of applications available as software packages Web-based software –unlimited software resource AI software –makes use of non-numerical algorithms –expert systems, pattern recognition, games

Software failures receive a lot more publicity than software engineering success stories. The software crisis predicted thirty years ago has never materialized and software engineering successes outnumber the failures. The problems that afflict software development are associated more with how to develop and support software properly, than with simply building software that functions correctly. Software Crisis

Software Myths Management myths. Customer myths. Practitioner’s myths. Myth? Reality?

Evolving Role of Software Software is both a product, and the means for delivering a product or service The most important product of our time: information Advances in hardware performance result in ever more complex software applications

Important Questions Why does it take so long to finish a software project? Why does it cost so much to develop software? Why do we deliver software with significant bugs still present? Why is it so hard to measure progress during development?

KEY POINTS OF TODAY’S LECTURE 1.Software is both a product and a vehicle for delivering a product. 2. Software is engineered, not manufactured. 3.Software doesn’t wear out, but it does deteriorate. 4.Most software continues to be custom built.