Design and implementation school management system

CHAPTER II: THEORETICAL CONCEPT

2.1 Introduction

The purpose of this part is to provide a brief description about terms that are

used during development of this project. It deals with theoretical concepts and fundamentals that support this project. It provides definitions and characteristics of technologies used. Since theoretical concepts involved are complex the description provides only the over view.

2.2 Information system and fundamentals

2.2.1 System

A set of interrelated components that function together to achieve one or more

results¹. For example, a computer System includes both hardware and software to process any information.

2.2.2 Information

Information is the result of data processing², the data is processed, manipulated,

organized, in order to be in suitable form for human interpretation.

2.2.3 Information system

Information system (IS)is an arrangement of people, data, processes, and

information technology that interact to collect, process, store, and provide as output the information needed to support an organization³.

Examples: Hotel Online Booking System

Student Online registration System

2.2.4 Information technology

Information Technology (IT), as defined by the Information Technology⁴

association of America (ITAA), means all computerized and auxiliary automated

¹ Saint JOSEPH Computer learning Center (System Analysis & Design e-Book) page 5

² Saint JOSEPH Computer learning Center (System Analysis & Design e-Book) page 5

³ Whitten & Bently, 2007, Systems analysis and design methods, 7th edition, McGraw-Hill,chap.1

4 http://en.wikipedia.org/wiki/Information technology, 15^th April, 2010

information handling, including system analysis and design, computer programming, data conversion, information storage and retrieval, data communication, voice, video, requisite systems controls, and simulation. Generally the term Information Technology is abbreviated with «IT»

2.3 Database concepts

2.3.1 Data

Data is a representation of facts, concepts, or instructions in a manner suitable

for communication, interpretation, or processing by humans or by automated means; data⁵ consists of basic facts that are the system's raw material.

2.3.2 Data versus information

Data and information are closely related, and in fact are often used

interchangeably. However it is useful to distinguish between data and information. Information is normally defined as data that has been processed in such a way that it can increase the knowledge of the person who uses the data.

2.3.3 Database

Database is an organized collection of related data⁶. It means that data are

structured in manner suitable to be stored, manipulated, and retrieved by users; By related I mean the data describe domain of interest to a group of users and that the users can use the data to answer questions concerning that domain.

2.3.4 Entity

It is a person, object, place, event, or concept in the user environment about

which the organization wishes maintain data.

2.3.5 Entity Relationship Diagram

An entity-relationship (ER) diagram is a specialized graphic that illustrates the

interrelationships between entities in a database. ER diagrams often use symbols to represent three different types of information.

⁵ Saint JOSEPH Computer learning Center (System Analysis & Design e-Book) page 5

⁶ Whitten & Bently, 2007, Systems analysis and design methods, 7th edition, McGraw-Hill ,chap3

Boxes are commonly used to represent entities. Diamonds are normally used to represent relationships and ovals are used to represent attributes.

2.3.6 Table

A table is a two-dimensional display of data values corresponding to an entity.

The columns of a table represent the characteristics of the entity, and the rows represent instance of the entity.

2.3.7 Record

A record is a generic term of a row in database, just like a card. A record very

often represents a piece of content. The dynamic functionality and much of the content of Mambo relies in a database in order to function.

2.3.8 Field

The location in a database record reserve for a particular type of data; for

example in library catalog, author, title; subject headings would all be stored in specific fields.

2.3.9 Attribute

A named property or characteristic of an entity that is of interest to an

organization. An example of attribute is «personnel_Id»

2.3.10 Primary key

The primary key is used to create relationships between tables. It's «the entry

keyed off of» to identify the record in question.

An otherwise meaningless surrogate value is often used for the primary key. The primary key for an entry must never change: if the referred to by a record in a different table, the relationship (link) will be often irretrievably broken.

2.3.11 Foreign key

A foreign key is a reference to a key in another table, meaning that the

referencing table has, as one of its attributes, the values of a key in the referenced table. Usually a foreign key will be a primary key in another table.

2.3.12 Data Modeling

It is a technique for organizing and documenting a system's data. Sometimes it is

called database modeling⁷ because it is eventually implemented as a database. The actual model is frequently called Entity Relationship Diagram (ERD), where entity means a class of persons, objects, events or concepts about which we need to capture and store data and relationship means association among the instance of one or more entity types.

Figure 1: Data modeling

Source: http://upload.wikimedia.org/wikipedia/commons/f/f4/4- 3_Data_Modelling_Today.jpg

2.3.13 Relational database

Relational database creates relationships between fields in tables explicitly

through keyed fields.

Because the relationships are not handled programmatically but are integral to the data itself, users can access the data without knowing the physical structure of the data (i.e. how data are written on disk). Logically, relational databases lend themselves very efficiently to many situations, and because their structure is transparent, they can be designed and modified relatively easily.

2.3.14 Database management system (DBMS)

A collection of programs that enable a user to enter, modify, manage, and delete

information in a database. There are different type of DBMSs, ranging from small systems that run on personal computers to huge systems that run on mainframes.

Database management system (DBMS)

Figure 2: Database management system (DBMS)

Source: http://www.unixspace.com/img/com.gif 2.4 Database in network environment

2.4.1 Network environment

2.4.2 Client/server architecture

A Network architecture ¹⁴ in which each computer or process on the network is either a client or a server.

Servers are powerful computers or process dedicated to managing disk drives (file servers), printers (print serves), or network traffic (network servers).

Client are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power. Another type of network architecture is known as a peer-to-peer architecture because each node has equivalent responsibilities.

Both client/server and peer-to-peer architectures are widely used, and each has unique advantages and disadvantages. Client-server architectures are sometimes called two-tier architectures.

Figure 3: Client/server architecture

Source: http://www.acm.org/ubiquity/volume_9/images/client_server_architecture.jpg

2.4.3 Client-server

Client/server describes the relationship between two computer programs in which

one program, the client, makes a service request from another program, the server, which fulfils the request. Although the client/server idea can be used by programs within a single computer, it is a more important idea in a network. In a network, the client/server model provides a convenient way to interconnect programs that are distributed efficiently across different locations.

2.4.4 Database server

A database server is a computer program that provides database services to

other computer programs or computers, as defined by the client-server model.

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Figure 4: Data server

Source: http://www.inera.it/opencms_inera/export/pics/inera/dataserver.gif

2.4.5 Web server

A computer program that is responsible for accepting HTTP requests from

clients, which are known as web browsers, and serving them HTTP responses along with optional data contents, which usually are web pages such as HTML documents and linked objects (images, etc.).

2.4.6 Web Browser

A web browser is a software application that enables a user to display and

interact with text, images, videos, music and other information typically located on a Web page at a website on the World Wide Web or a local area network. Some of the popular browsers are: Internet Explorer, Mozilla Firefox, Netscape, and Opera and further

2.4.7 Web page

A web page⁸ is a block of data available on the world-wide web, identified by an

URL.

2.4.8 Website

A website⁹ is a set of interconnected web pages, usually including a homepage,

generally located on the same server, and prepared and maintained as a collection of information by a person, group, or organization.

⁸ http://www.learnthat.com/define/view.asp?id=2348 22^th April, 2010 ⁹ http://www.answers.com/topic/website 22^th April, 2010

¹⁴ http://www.webopedia.com/TERM/Cclient server architecture.html (accessed: 23/05/2010)

2.5 Tools and Language used 2.5.1 HTML

Hypertext Markup Language" is the authoring language used to create documents on the World Wide Web (www). HTML is similar to SGML, although it is not a strict subset.

HTML defines the structure and layout of a Web document by using a variety of tags and attributes. All the information you'd like to include in your Web page fits in between the tags.

There are hundreds of other tags used to format and layout the information in a web page. Tags are also used to specify hypertext links. These allow Web developers to direct users to other web pages with only a click of the mouse on either an image or word(s).

2.5.2 PHP

PHP is a powerful tool for making dynamic and interactive Web pages.PHP is the widely-used, free, and efficient alternative to competitors such as Microsoft's ASP.PHP is an HTML-embedded scripting language¹⁰. Much of its syntax is borrowed from C, Java and Perl with a couple of unique PHP-specific features thrown in. The goal of the language is to allow web developers to write dynamically generated pages quickly

2.5.3 Mysql

Mysql is a relational database management system. It stores data in separate tables rather than putting all the data in one big storeroom. This adds speed flexibility. The Mysql database server is very fast, reliable cheaper and easy to use and learn. Mysql today offers a rich and useful set of functions. Its connectivity, speed and security make it highly suited for accessing databases on the Internet, it also supports clustering technology.

¹⁰ http://www.tizag.com/phpT/ 15 Marchr, 2010

2.5.4 Apache server

Apache has been the world's most popular Web server (HTTP server) on the

Internet since April 1996 and is generally considered to be more stable than other servers. The name Apache derives from the word «patchy» that the Apache developers used to describe early versions of their software. This web server has been chosen because of its performance regarding to the other servers

2.5.5 JavaScript

A popular scripting language that is widely supported in Web browsers and other

Web tools. It adds interactive functions to HTML pages, which are otherwise static, since HTML is a display language, not a programming language.

On the client, JavaScript is maintained as source code embedded into an HTML page. On the server, it is compiled into byte code (intermediate language), similar to Java programs.

2.5.6 CSS

It stands for Cascading Style Sheet. Style sheet refers to the document itself.

Style sheets have been used for document design for years. They are the technical specifications for a layout, whether print or online. Print designers use style sheets to insure that their designs are printed exactly to specifications.