Computer Software and Software Systems

Computer Software and Software Systems

[ From chapter-5 of the book "Information Technology in Banking" written by Abul Kashem Md. Shirin and Nusrat Tamanna Prianka and published by Institute of Bankers, Bangladesh (IBB) ]

1.         Computer Software

Computer is a machine which can’t work itself. To start and make the computer operative, a computer program is required. After the computer is made operative, another set of specific programs are required to perform a specific task. Such programs are collectively known as computer software. Computer software can be divided into two types – System Software and Application Software.

1.1.      System Software

The Software used to start the computer and make the computer operational is called System Software. On the other hand, when the Application Software instructs a device of the computer system to do something, the System Software first translates the instruction into a language which is understandable to the device. The System Software then sends the translated instructions to the respective devices. The devices act accordingly. As such the System Software is positioned in between the computer hardware and the Application Software. The Operating Systems are popular System Software.

The Operating System was first developed for the Mainframe Computer in 1960s. Later on various operating systems like Macintosh, Disk Operating System (DOS), Unix and Windows were developed. The Microsoft Company of USA is the developer of DOS and Windows operating systems. The functionalities of an Operating System are as mentioned below:

1.      To make the computer active and usable

2.      To communicate between hardware and application software

3.      To accept and execute the instruction of a user

4.      To fetch a program into the main memory and process it

5.      To control the activities like writing, storing and reading data to/from Disk.

1.2.      Application Software

A program used to perform a specific job using a computer is called Application Software. For example, Word Star, Word Perfect and MS Word are used for typing or word processing; Lotus 1-2-3, Quattro Pro, MS Excel are used for calculation or spread sheet analysis; Netscape Navigator and Internet Explorer are used for web browsing; Out Look, Messenger and Eudora are used for e-mail checking, Power Point is used for presentation; Auto CAD is used for Engineering drawing; SPSS is used for statistical analysis; Access, SQL Server and Oracle are used for data manipulation and storage. These software are developed by different company to sale commercially in the market. The users buy them and use at home and office. For this reason, they are called General Purpose Application Software.

Programmers also develop application software for a specific activity of a specific organization. These are called Application Specific program. For example, a group of programmer or a company may develop a program for a bank for recording transactions of its customers, and at the day-end, to prepare reports like Balance Sheet and Income Statement. The program written for a Bank may not fit to the requirement of another bank, as the transaction rules may be different for different banks.

2.         Programming Language

The program which is used for writing a General Purpose Program or an Application Specific Program is called Programming Language. Large companies develop Programming Language to sale commercially. Programmers buy these Programming Languages and use one or more of them to write a general-purpose or application-specific program. The commonly used programming languages are:

·         C / C++

·         Assembly language

·         COBOL

·         FORTRAN

·         BASIC / BASICA / Q-Basic / Quick Basic

·         Visual Basic

·         .Net

·         HTML

·         JAVA

·         FoxPro / FoxBase / dBase

The programming languages can be divided into three types:

·         Low-Level Languages

·         High-Level Languages

·         Object Oriented Languages

2.1.      Low-Level Language

Low-Level languages are languages where the computer programs are written using machine code (binary or hexadecimal codes) or mnemonic code. Low-level language consists of two computer languages – Machine Language and Assembly Language.

Machine Language: During the initial stage of development of Computers, programmers had used machine code, i.e. binary and hexadecimal codes for writing computer program. These computer programs which use machine code from writing a specific user programs are called Machine Language. Machine language can execute very fast and efficiently. However if a specific user program is written using a machine language for a particular computer it can’t be run on another computer. Writing, reading and modifying such a computer program is very complex and time consuming. To solve this problem, Assembly Language was developed for writing computer program much comfortably.

Assembly Language: In Assembly Language, instead of machine code such as binary and hexadecimal codes, mnemonic codes are used. For example, assembly language programs use SUB to perform a subtraction operation. For this, assembly language is also called Symbolic language. For developing an operating system, a game or a high-level language, normally the assembly language is used.

2.2.      High Level Language

A high-level language (developed using assembly language) is very user friendly. It’s syntaxes are very similar to English language. A high-level language is used by computer programmers to develop an application specific computer program. The following are the example of high=level languages:

·         COBOL (Common Business Oriented Language)

·         BASIC (Beginners All-purpose Symbolic Instruction Code)

·         FORTRAN (FORmula TRANslator)

·         C

·         PASCAL

2.3.      Object Oriented Language

Object Oriented Language is language that supports the idea of bundling instructions and data into a set of programming code - called an object. The object can be used repeatedly throughout the program. The technique of writing a computer program using an object oriented language is called Object Oriented Programming or OOP. An OOP has the following three characteristics:

a.         Polymorphism

Polymorphism means different objects respond distinctively to the same message. For example, when we send the same message – “Speak” to a cat object, a dog object, and a cow object, each of one respond appropriately. The cat purrs, the dog barks, and the cow moos.

b.         Inheritance

Inheritance means that the language gives us the ability to extend or enhance existing objects. The child object created from the parent object will get all the properties of the parent object and also it can have its own properties.

c.         Encapsulation

Encapsulation means that the data and instructions for variables are wrapped up together and treated as a unit. The blueprints for these variables are called classes and the units are called objects.

The example of object oriented language is C++ and Java.

3.         Database Management System

Programming language is used to write a computer program for a specific purpose. In such a computer program, there may have some input screens through which the users input data into the computer system. These data are stored into the computer system for further use or generation of reports later on. For storing data into the computer system in easy retrievable manner, Database is used. A database is a computer program used to store and manipulate data. In a database, the data is kept at row and column as under:

Column Row	1 (Account No)	2 (Name of Customer)	3 (Account Balance)
1	S101	Ornab Alinur	5000.00
2	S102	Abrar Rahman	3010.00
3	C101	Aminul Islam	2505.00
4	C102	Raiyan Islam	4017.00

In the above example, the file where these information will be stored is called database table. One or more database table together creates a Database. The database and all of its tables have different name. All the tables have rows and columns. In the above example, there are 4 rows and 3 columns.

There are some specific commands for a database to create/modify/delete table, add rows into the table, and ready/modify/delete rows from the table. These commends are called Data Description Language (DDL) and Data Manipulation Language (DML).

Database Management System (DBMS) is a system which not only stores data, but also provides Data Description Language (DDL) and Data Manipulation Language (DML) for the users to create facilities for storing data and manipulation of the stored data.

According to Graham Taylor, the DBMS is a general set of programs designed to link with the application programs of the various users and departments, and the database itself. It controls access (who can use it) and includes facilities for data independences, integrity and security.

DBMS is very useful for a bank. The balance and transactions are recorded into the DBMS. Oracle, DB2 and SQL server are three widely used DBMS in banks.

The officer who is engaged for planning, organizing and controlling a DBMS is called Database Administrator (DBA). A DBA is responsible for security and availability of data in the DBMS. If the database is crashed for any reason, it is the responsibility of the DBA to make the data available within shortest possible time. For this reason, the DBA always (normally at the day-end) keeps a copy of the database into a Tape Cartridge and another computer system. This is called taking Backup of the database.

4.         Internet and related terminologies

4.1.      Internet

The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic and optical networking technologies. The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support electronic mail.

Most traditional communications media including telephone, music, film, and television are being reshaped or redefined by the Internet. Newspaper, book and other print publishing are having to adapt to Web sites and blogging. The Internet has enabled or accelerated new forms of human interactions through instant messaging, Internet forums, and social networking. Online shopping has boomed both for major retail outlets and small traders. Business-to-business and financial services on the Internet affect supply chains across entire industries.

The origins of the Internet reach back to the 1960s with both private and United States military research into robust, fault-tolerant, and distributed computer networks. The funding of a new U.S. backbone by the National Science Foundation, as well as private funding for other commercial backbones, led to worldwide participation in the development of new networking technologies, and the merger of many networks. The commercialization of what was by then an international network in the mid 1990s resulted in its popularization and incorporation into virtually every aspect of modern human life. As of 2009, an estimated quarter of Earth's population used the services of the Internet.

The Internet has no centralized governance in either technological implementation or policies for access and usage; each constituent network sets its own standards. Only the overreaching definitions of the two principal name spaces in the Internet, the Internet Protocol (IP) address space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise.

4.2.      WWW

The World Wide Web, abbreviated as WWW and commonly known as the Web, is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them by using hyperlinks. Using concepts from earlier hypertext systems, English engineer and computer scientist Sir Tim Berners-Lee, now the Director of the World Wide Web Consortium, wrote a proposal in March 1989 for what would eventually become the World Wide Web. The World-Wide Web (W3) was developed to be a pool of human knowledge, and human culture, which would allow collaborators in remote sites to share their ideas and all aspects of a common project.

4.3.      Hypertext

Hypertext is text displayed on a computer or other electronic device with references (hyperlinks) to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Apart from running text, hypertext may contain tables, images and other presentational devices. Hypertext is the underlying concept defining the structure of the World Wide Web, making it an easy-to-use and flexible format to share information over the Internet.

4.4.      Hyperlinks

Hyperlink is a reference to a document that the reader can directly follow, or that is followed automatically. The reference points to a whole document or to a specific element within a document. A user following hyperlinks is said to navigate or browse the hypertext.

4.5.      Web browser

A web browser or Internet browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. Although browsers are primarily intended to access the World Wide Web, they can also be used to access information provided by Web servers in private networks or files in file systems.

4.6.      Web Page

A web page or webpage is a document or resource of information that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a monitor or mobile device. This information is usually in HTML or XHTML format, and may provide navigation to other webpages via hypertext links. Webpages may be retrieved from a local computer or from a remote web server. The web server may restrict access only to a private network, e.g. a corporate intranet, or it may publish pages on the World Wide Web.

Webpages may consist of files of static text and other content stored within the web server's file system (static webpages), or may be constructed by server-side software when they are requested (dynamic webpages).

4.7.      Internet vs WWW

The terms Internet and World Wide Web are often used in everyday speech without much distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is a global data communications system. It is a hardware and software infrastructure that provides connectivity between computers. In contrast, the Web is one of the services communicated via the Internet. It is a collection of interconnected documents and other resources, linked by hyperlinks and URLs.

4.8.      URL

Uniform Resource Locator (URL) is a Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it. The best-known example of a URL is the "address" of a web page on the World Wide Web, e.g. http://www.dbbl.com.bd.

5.         E-mail

Electronic mail, commonly called email or e-mail, is a method of exchanging digital messages across the Internet or other computer networks. Originally, email was transmitted directly from one user to another computer. This required both computers to be online at the same time. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver and store messages. Users no longer need be online simultaneously and need only connect briefly, typically to an email server, for as long as it takes to send or receive messages.

An email message consists of two components, the message header, and the message body, which is the email's content. The message header contains control information, including, minimally, an originator's email address, one or more recipient addresses and a subject header field. Email can also carry multi-media content attachments.