Database System Concepts Essay

Submitted By yoganand1627
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Pages: 19

Chapter 9: Application Design and
Development

Database System Concepts ­ 6th Edition

9.1

©Silberschatz, Korth and Sudarshan

Chapter 9: Application Design and Development
 Application Programs and User Interfaces
 Web Fundamentals
 Servlets and JSP
 Application Architectures
 Rapid Application Development
 Application Performance
 Application Security
 Encryption and Its Applications

Database System Concepts ­ 6th Edition

9.2

©Silberschatz, Korth and Sudarshan

Application Programs and User Interfaces
 Most database users do not use a query language like SQL
 An application program acts as the intermediary between users and

the database


Applications split into


front­end



middle layer



backend

 Front­end: user interface


Forms



Graphical user interfaces



Many interfaces are Web­based

Database System Concepts ­ 6th Edition

9.3

©Silberschatz, Korth and Sudarshan

Application Architecture Evolution
 Three distinct era’s of application architecture


mainframe (1960’s and 70’s)



personal computer era (1980’s)



We era (1990’s onwards)

Database System Concepts ­ 6th Edition

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©Silberschatz, Korth and Sudarshan

Web Interface
 Web browsers have become the de­facto standard user interface to

databases


Enable large numbers of users to access databases from anywhere 

Avoid the need for downloading/installing specialized code, while providing a good graphical user interface




Javascript, Flash and other scripting languages run in browser, but are downloaded transparently

Examples: banks, airline and rental car reservations, university course registration and grading, an so on.

Database System Concepts ­ 6th Edition

9.5

©Silberschatz, Korth and Sudarshan

The World Wide Web
 The Web is a distributed information system based on hypertext.
 Most Web documents are hypertext documents formatted via the

HyperText Markup Language (HTML)

 HTML documents contain


text along with font specifications, and other formatting instructions



hypertext links to other documents, which can be associated with regions of the text.



forms, enabling users to enter data which can then be sent back to the Web server

Database System Concepts ­ 6th Edition

9.6

©Silberschatz, Korth and Sudarshan

Uniform Resources Locators
 In the Web, functionality of pointers is provided by Uniform Resource

Locators (URLs).

 URL example:

http://www.acm.org/sigmod


The first part indicates how the document is to be accessed


“http” indicates that the document is to be accessed using the
Hyper Text Transfer Protocol.



The second part gives the unique name of a machine on the
Internet.



The rest of the URL identifies the document within the machine.

 The local identification can be:


The path name of a file on the machine, or



An identifier (path name) of a program, plus arguments to be passed to the program
– E.g., http://www.google.com/search?q=silberschatz

Database System Concepts ­ 6th Edition

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©Silberschatz, Korth and Sudarshan

HTML and HTTP
 HTML provides formatting, hypertext link, and image display features


including tables, stylesheets (to alter default formatting), etc.

 HTML also provides input features


Select from a set of options
– Pop­up menus, radio buttons, check lists



Enter values
– Text boxes



Filled in input sent back to the server, to be acted upon by an executable at the server

 HyperText Transfer Protocol (HTTP) used for communication with the

Web server

Database System Concepts ­ 6th Edition

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©Silberschatz, Korth and Sudarshan

Sample HTML Source Text
<html>
<body> <table border>
<tr> <th>ID</th> <th>Name</th> <th>Department</th> </tr>
<tr> <td>00128</td> <td>Zhang</td> <td>Comp. Sci.</td> </tr>
….
</table> <form action="PersonQuery" method=get>
Search for: <select name="persontype"> <option value="student" selected>Student </option> <option…