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 front-end middle layer backend Front-end:user interface ·Forms Graphical user interfaces Many interfaces are Web-based Database System Concepts-7th Edition 9.3 ©Silberscha乜，Korth and Sudarshan
Database System Concepts - 7 9.3 ©Silberschatz, Korth and Sudarshan th Edition 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 ▪ front-end ▪ middle layer ▪ backend ▪ Front-end: user interface • Forms • Graphical user interfaces • Many interfaces are Web-based
Application Architecture Evolution Three distinct era's of application architecture Mainframe(1960's and 70's) Personal computer era(1980's) Web era(mid 1990's onwards) Web and Smartphone era(2010 onwards) Terminals Desktop PCs Web browsers Application Application Program Program Propietary Network or dial up phone lines Local Area Network Internet Mainframe Computer Web Application Server Database Database (a)Mainframe Era (b)Personal Computer Era (c)Web era Database System Concepts-7th Edition 9.4 @Silberschatz,Korth and Sudarshan
Database System Concepts - 7 9.4 ©Silberschatz, Korth and Sudarshan th Edition Application Architecture Evolution ▪ Three distinct era’s of application architecture • Mainframe (1960’s and 70’s) • Personal computer era (1980’s) • Web era (mid 1990’s onwards) • Web and Smartphone era (2010 onwards)
Web Interface Web browsers have become the de-facto 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-7th Edition 9.5 @Silberschatz,Korth and Sudarshan
Database System Concepts - 7 9.5 ©Silberschatz, Korth and Sudarshan th Edition Web Interface ▪ 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. Web browsers have become the de-facto standard user interface to databases
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 value="instructor">Instructor </option> </select><br> Name:<input type=text size=20 name="name"> <input type=submit value="submit"> </form> </body></html> Database System Concepts-7th Edition 9.9 @Silberschatz,Korth and Sudarshan
Database System Concepts - 7 9.9 ©Silberschatz, Korth and Sudarshan th Edition 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 value="instructor"> Instructor </option> </select> <br> Name: <input type=text size=20 name="name"> <input type=submit value="submit"> </form> </body> </html>
Display of Sample HTML Source ID Name Department 00128 Zhang Comp.Sci. 12345 Shankar Comp.Sci. 19991 Brandt History Search for: Student Name: submit Database System Concepts-7th Edition 9.10 @Silberschatz,Korth and Sudarshan
Database System Concepts - 7 9.10 ©Silberschatz, Korth and Sudarshan th Edition Display of Sample HTML Source Search for: Name: Student submit