JNDI DataSource Configuration in JBoss with DB2 in Eclipse Example

Assume that Eclipse is configured with JBoss Application Server 4.0. Before an application can get data from any Database (db2, Postgress, MySql , Oracle, etc..), it needs to establish a connection to the database. In our example we are going to connect with db2 database (eg. Employee). This can be done using JDBC in following ways.

1. Use the DriverManager class to establish a connection -> Load the Db2 JDBC Driver using Class.forName() & Create a connection to a db2 database using DriverManager.getConnection() method

2. Connect to the db2 database through a DataSource object. This is to use an implementation of the javax.sql.DataSource interface in conjunction with the Java Naming and Directory Interface (JNDI).

Now we are going to connect using the IInd way i.e using an implementation of the javax.sql.DataSource interface in conjunction with JNDI. Please follow the following steps for successful data base connection with db2 . .

It is always better to recycle and reuse existing connections to a data base than opening a new connection. So it needs to maintain a DB connection pool. JBoss supports DBCB which uses the Jakarta-Commons Database Connection Pool

Steps to be followed to configure JNDI Data Source in JBoss 4.0 with DB2 (in our example: jdbc/JbossTestDS)

1) Make an appropriate JDBC driver for DB2 available to JBoss & to your web application (Necessary driver class files for Db2 are available in the JARs db2jcc.jar, db2jcc_license_cisuz.jar, db2jcc_license_cu.jar. Copy these jars to Jboss (Drive:\jboss-4.0.0\server\default\lib) also include these jars to build path of the application )

2) Three Important XML files are to be configured. They are web.xml, Jboss-web.xml, *-ds.xml. Details are given below.

Assume that installation folder of Jboss 4.0 Application Server is D:\jboss-4.0.0. JNDI name is JbossTestDS, Database Name is Employee.

a) Define a reference lookup name (eg. jdbc/JbossTestDS) to an external resource in the WEB-INF\web.xml. Modify the web application deployment descriptor (/WEB-INF/web.xml) to define the JNDI name for the Datasource (ie. jdbc/datasourcename) for the web application level.

web.xml

The following lines will be added in the web.xml before </web-app> for declaring resource requirements.

<resource-ref>
<description>Database Connection</description>
<res-ref-name>jdbc/JbossTestDS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref> 


b) Next Modify the jboss-web.xml located in the WEB-INF in the application.

jboss-web.xml

The following lines will be added in the jboss-web.xml between <jboss-web> </jboss-web>

<resource-ref>
<res-ref-name>jdbc/JbossTestDS
<res-type>javax.sql.DataSource<jndi-name>java:/jdbc/JbossTestDS </resource-ref>

More than one resource reference also can be defined.

c) Deployment descriptor (web.xml) only define a resource adaptor. This resource adapter can be used by integrating into the JBoss application server using a ds.xml descriptor file. Configure JBoss *-ds.xml ( in our example : jdbc-db.xml ) located in D:\jboss-4.0.0\server\default\deploy
jdbc-ds.xml

The following lines will be added in the jdbc-ds.xml between <datasources> </datasources>

<local-tx-datasource>
<jndi-name>jdbc/JbossTestDS</jndi-name>
<connection-url>jdbc:db2://localhost:50000/employee</connection-url>
<driver-class>com.ibm.db2.jcc.DB2Driver</driver-class>
<user-name>abc</user-name>
<password>xyz</password>
<min-pool-size>0</min-pool-size>
<metadata>
<type-mapping>DB2</type-mapping>
</metadata>
</local-tx-datasource>

Note that the jndi name jdbc/JbossTestDS must match the resource reference specified in the web application deployment descriptor

Finally write Java Code to use the resource.

ConnectionFactory.java

    
 public static Connection getConnection() throws CDRCFatalException {

  Context  m_ctxLookup = null;

  DataSource  ds = null;

  Connection  conn = null;

 try {

    Context initCtx = new InitialContext();

    Context envCtx = (Context) initCtx.lookup("java:comp/env");

     ds = (DataSource)   envCtx.lookup("jdbc/JbossTestDS");

 } catch (NamingException exc) {

   System.out.println("Lookup fail db " + exc.toString()+ " The context is " + m_ctxLookup);

   throw new CDRCFatalException( exc.getMessage(), "01001" );

  }



  try {

      conn = ds.getConnection();

  }catch (SQLException exc) {

   System.out.println(" Fail to connect database " + exc.toString()+ " The context is " + m_ctxLookup);

   throw new CDRCFatalException( exc.getMessage(), "02006");

  }

  return conn;

 }

You can call the above getConnection() static method whereever connection is required in Java Code

 Connection conn = null;

conn = ConnectionFactory.getConnection();

 

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How to Configure JDBC Datasource (JNDI) in Tomcat 7 with DB2 in Ecplise Example.

The following steps tells how to Configure JDBC Data Resources (JNDI) in Tomcat 7 with DB2 in Ecplise with Example. Assume that Eclipse is configured with Apache Tomcat Application Server 7.0.

A database connection pool creates and manages a pool of connections to a database. It is always better to recycle and reuse already existing connections to a dB than opening a new connection. Tomcat supports DBCP connection pool from the Commons project by default. It is also possible to use any other connection pool that implements javax.sql.DataSource

Suppose if you need to access db2 database via a JDBC driver, follow the following steps for successful data base connection with db2.

Steps to be followed to configure JDBC Data Resources (JNDI) in Tomcat 7 with DB2 (in our example jdbc/javaOnlineDS)

In Brief :
1) Place appropriate JDBC drivers of DB2 to Tomcat for  your web application (i.e place it inside WEB-INF\lib)
2) Configure web.xml, context.xml files as described in the detail section.

In Detail :
Copy all necessary JDBC drivers of DB2 database, to the lib folder under WEB-INF. i.e  copy db2 jdbc drivers db2java.zip, db2jcc.jar, db2jcc_license_cisuz.jar, db2jcc_license_cu.jar to the lib folder.

Next, Declare Resource Requirements in web.xml. Modify the web application deployment descriptor (/WEB-INF/web.xml) to declare the JNDI name for the Database resource (ie. jdbc/javaOnlineDS) for the web application level.

web.xml
The following lines will be added in the web.xml before </web-app> for declaring resource requirements.

<resource-ref>

<description>DB Connection Pool</description>

<res-ref-name>jdbc/javaOnlineDS</res-ref-name>

<res-type>javax.sql.DataSource</res-type>

<res-auth>Container</res-auth>

</resource-ref >

context.xml

The following lines will be added in the context.xml under META-INF between <Context> </Context>

<Resource name="jdbc/javaOnlineDS" auth="Container"   type="javax.sql.DataSource" username="abc" password="*****" driverClassName="com.ibm.db2.jcc.DB2Driver"  url="jdbc:db2://localhost:50000/test" maxActive="8" maxIdle="4" />

Note that the resource name jdbc/javaOnlineDS must match the value specified in the web application deployment descriptor


Now let us write Java code to use the resource. Create a connection class

ConnectionFactory.java

package javaonline;

import java.sql.Connection;

import java.sql.SQLException;

import javax.naming.Context;

import javax.naming.InitialContext;

import javax.naming.NamingException;

import javax.sql.DataSource;


public class ConnectionFactory {

 
  public static Connection getConnection()  {

    Context  m_ctxLookup = null;

    DataSource  dataSource = null;

    Connection  conn  = null;


   try {
 
      Context initCtx = new InitialContext();

      Context envCtx = (Context) initCtx.lookup("java:comp/env");

      dataSource = (DataSource)   envCtx.lookup("jdbc/javaOnlineDS");

    } catch (NamingException exc) {

      System.out.println("Lookup fail of database " + exc.toString()+ "The context is " + m_ctxLookup);

       }


    try {

      conn = dataSource.getConnection();

    }catch (SQLException exc) {

      System.out.println("Getting Connection. Fail of database " + exc.toString()+ "The context is " + m_ctxLookup);

    }

    return conn;

   }

}



Call the above getConnection() static method in DAO class

public class GetDetailsDAO { 
public String getData() throws  JSONException

 {  

  PreparedStatement ps = null;

     ResultSet rs = null;

     Connection conn = null;

    try

     {     

      conn = ConnectionFactory.getConnection();


      String strQry = "SELECT * from Employee";

      ps = conn.prepareStatement(strQry);

      rs = ps.executeQuery();

  ----

  ----
         } catch (SQLException se) {}

 }
}

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