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Chapter 5Chapter 5Client-Server Client-Server Application Application

Development Development (2-Tier Architecture)(2-Tier Architecture)

Database Application DevelopmentDatabase Application DevelopmentSSK 3408SSK 3408

Interfacing with the Database

The same table open with Notepad:

Data stored in a database in a proprietary format. Application faces the same problem as Notepad or any other application trying to

access data in an unknown format. A software interface is needed between your web application and the database

allowing the application and the database to talk to each other. Three common interfaces let applications communicate with databases.

Open Database Connectivity, or ODBC; OLE DB (object linking & embedding database); and Java Database Connectivity, or JDBC.

Understanding JSP Connection A JSP application must connect to a database

through a JDBC driver. The driver acts as an interpreter that lets a JSP

application communicate with a database. Specify certain parameter values to connect

through your JDBC driver. For the parameter values specific to your driver, see the driver vendor’s documentation or consult your system administrator.

You can also use an ODBC driver (and so a Windows DSN) if you have a JDBC-ODBC Bridge driver.

Understanding JSP Connection ..cont.

JDBC A standard API (Application Program Interface) for

accessing relational databases from a Java program.  This interface makes it easy to access a database

because it provides an abstract layer that hides the low-level details, such as managing sockets.

The basic steps to get program up and running are: Load the driver Define the connection URL Establish the connection Create a statement Execute a query and retrieve the results, or make changes to the

database Disconnect from the database

classes12.jar & nls_charset12.jar

Edit CLASSPATH.;D:\app\Admin\product\11.1.0\client_1\

jdbc\lib\classes12.jar;D:\app\Admin\product\11.1.0\client_1\jdbc\lib\nls_charset12.jar

To Start up Orion Server

JDBC Detail Process 1. Load the driver

2. Define the Connection URL

Class.forName(“oracle.jdbc.driver.OracleDriver”);

String hostname = “10.101.100.13”;int port = 1521;String sid = “orcl”;String oracleURL = “jdbc:oracle:thin:@”+hostname+”:”+port+”:”+sid;

3. Establish the Connection

4. Create a Statement

5. Execute a Query

JDBC Detail Process ..cont.

String username = “salmi”;String password = “secret”;Connection conn = DriverManager.getConnection(oracleURL, username, password);

Statement stmt = conn.createStatement();

String query = “Select empid, fname, salary, commission from employee”;Resultset rs = stmt.executeQuery(query);

6. Process the Result

7. Close the Connection

JDBC Detail Process ..cont.

while (rs.next()) { out.println (“Empid: “+rs.getString(1)); out.println (“First Name: “+rs.getString(2)); out.println (“Salary: “+rs.getString(3)); out.println (“Commission: “+rs.getString(4));}

cnn.close();

Basic JDBC Example<%@ page contentType="text/html; charset=iso-8859-1" language="java" import="java.sql.*" errorPage="" %><%try { Class.forName("oracle.jdbc.driver.OracleDriver"); String hostname = “172.16.60.13";

int port = 1521;String sid = "orcl";String oracleURL = "jdbc:oracle:thin:@"+hostname+":"+port+":"+sid;String username = “XXXX";String password = “XXXX";Connection conn = DriverManager.getConnection(oracleURL, username, password);Statement stmt = conn.createStatement();String query = "Select empid, fname, salary, commission from employee";ResultSet rs = stmt.executeQuery(query);

Basic JDBC Example …cont.int ctr = 1;out.println("<H1>MY FIRST JSP</H1>");out.println("<table border = 1>");out.println("<tr><th>No.</th><th>EmpID</th><th>FirstName</th><th>Salary</th><th>Commission</th></tr>");

while (rs.next()) { out.println("<tr><td>" +

ctr + "</td><td> " + rs.getString(1) + "</td><td> " + rs.getString(2) + "</td><td> " + rs.getString(3) + "</td><td> " + rs.getDouble(4) + "</td>"); out.println("</tr>"); ctr = ctr + 1; } conn.close(); } catch (ClassNotFoundException cnfe) { System.out.println("Error loading driver: "+cnfe); } %>

Output of JDBC Example