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This article guides you through the JDBC features in the Apache Geronimo appplication server. To demonstrate the JDBC features, we use a simple Inventory application which has JSP, Servlets to handle web related features and inbuilt Derby as database.

Inventory Application will use the Service Provider Interface (SPI) method to access its database. In this method the application uses a JDBC DataSource interface to establish connections with the database. This is the preferred access method for a JEE application for several reasons:

• Program code will be totally database independent. Driver information, database location, and configuration parameters are stored in the JEE Server.
• It allows the use of connection pooling. The JEE Server connection manager effectively manages connections to greatly improve performance and scalability.
• It enables the database to be used by Enterprise JavaBeans (EJB) to implement business logic as part of the JEE Server. Implementing an EJB tier, although not required, lays the foundation for creating a highly scalable, distributed application architecture.

After reading this article you should be able get the best out of the JDBC features of Geronimo, such as defining database pools and using DataSources to access databasessample illustrates direct use of JDBC connections from a servlet. For details on outbound connection support see Connectors and Transaction Management. Generally direct use of JDBC is not advised unless you have performance constraints or need for dynamic jdbc (such as in a database browser) that make the use of JPA impractical.

This article is organized in to following sections.

Overview of JDBC Features

JDBC implementation in application servers vary from application server to other. Following table gives a feature list of JDBC in Apache Geronimo.

...

Feature

...

Description

...

JDBC access

...

Geronimo does not have any direct integration with JDBC but supports access through the generic J2CA framework. The TranQL project has J2CA adapters for various databases.

...

JCA implementation

...

Geronimo supports the JCA 1.5 specification and is backward compatible to the JCA 1.0 specification.

...

Data sources supported

...

TranQL has generic wrappers for each data sources.

...

...

TranQL has specialized drivers for certain databases (including Apache Derby, Oracle and DB2) that provide a tighter integration with the advanced features of the driver.
It is at this level that features such as load-balancing and failover would be provided. You can also use a C-JDBC wrapper for providing database clustering and failover.

...

XA support

...

Supports XA transactions, Local Transactions, and No transaction.

...

Connection Manager Configurability

...

The J2CA framework is interceptor based which allows different parts of the connection framework to be plugged in.

...

JTA implementation

...

Transaction support is provided through Geronimo Specific Transaction Managing Framework and HOWL.

...

Connection pooling and management

...

Custom Geronimo Code and TranQL used for connection pooling and management.

...

Legacy driver support

...

Geronimo provides this through the TranQL- connector JDBC to JCA wrapper in Geronimo. Supports JDBC 3.0 and 2.1.

Application Overview

The Inventory application in this article only supports three basic usecases of such applications.

1. Add Items to the Stock
2. Receive Items
3. Issue Items
   The application workflow starts with adding item information to the stock. Then it allows enter goods receiving and issuing information. All those updated information are stored in the inbuilt sample database, by default Derby database.

The Inventory Web Application has following list of pages

...

• org.apache.geronimo.samples.inventory
  • Item - represents Item in the Inventory.
• org.apache.geronimo.samples.inventory.services
  • InventoryManager - represents list of services offered by the inventory.
• org.apache.geronimo.samples.inventory.dao
  • ItemDAO - contains all database access methods.
• org.apache.geronimo.samples.inventory.exception
  • DuplicateItemIdException - custom exception to handle duplication item id scenario.
  • ItemException - wraps data access exceptions (NamingException, SQLException).
  • NotSufficientQuantityException - Custom exception to handle not sufficient quantity situation.
• org.apache.geronimo.samples.inventory.util
  • DBManager - handle database related activities such as issuing database connections.
  org.apache.geronimo.samples.inventory.web
  • AddItemServlet - dispatch add item information to service layer.
  • IssueingServlet - dispatch issuing items information to service layer.
  • RecievingServlet ReceivingServlet - dispatch receiving items information to service layer.

...

This application defines a datasource with the help of the geronimo -web.xmlplan and web.xml deployment plans. geronimo-web.xml adds a link to the database pool that is packaged with the EAR fileThe Geronimo plan from inventory-jetty or inventory-tomcat links the internal JNDI name "java:comp/env/jdbc/InventoryDS" to the sample database.

<?xml version="1.0" encoding="UTF-8"?>
<web-app
	 xmlns="http://geronimo.apache.org/xml/ns/j2ee/web-2.0.1">
	
	<environment>
		<moduleId>
			<groupId>org  <dep:environment xmlns:dep="http://geronimo.apache.org/xml/ns/deployment-1.2">
    <dep:moduleId>
      <dep:groupId>org.apache.geronimo.samples</dep:groupId>
      <dep:artifactId>inventory-jetty</dep:artifactId>
      <dep:version>2.2-SNAPSHOT</dep:version>
      <dep:type>car</dep:type>
    </dep:moduleId>
    <dep:dependencies>
      <dep:dependency>
        <dep:groupId>org.apache.geronimo.samples<configs</dep:groupId>
			<artifactId>inventory-war</artifactId>
			<version>2.1</version>
        <dep:artifactId>jasper</dep:artifactId>
        <dep:version>2.2-SNAPSHOT</dep:version>
        <dep:type>car</dep:type>
      </dep:dependency>
      <dep:dependency>
        <dep:groupId>org.apache.geronimo.configs</dep:groupId>
        <dep:artifactId>jetty6</dep:artifactId>
        <dep:version>2.2-SNAPSHOT</dep:version>
        <dep:type>car</dep:type>
      </dep:dependency>
      <dep:dependency>
        <dep:groupId>org.apache.geronimo.samples</dep:groupId>
        <dep:artifactId>sample-datasource</dep:artifactId>
        <dep:version>2.2-SNAPSHOT</dep:version>
        <type>war<<dep:type>car</dep:type>
		      </moduleId>
		<dependencies></dependencies>		
	</environment>
		
	dep:dependency>
    </dep:dependencies>
    <dep:hidden-classes/>
    <dep:non-overridable-classes/>
  </dep:environment>
  <context-root>/inventory</context-root>
	
	  <!-- define a reference name to the db pool-->
	  <resource-ref>
        <ref-name>jdbc/InventoryDS</ref-name>
        <resource-link>InventoryPool<link>SampleTxDatasource</resource-link>
    </resource-ref>    
</web-app>

Following is the web.xml of the Inventory application. It uses same name as in the geronimo-web.xml, which is used to create declares the name "java:comp/env/jdbc/InventoryDS" used in ItemDAO to lookup the datasource.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
	         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
	 http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
	         version="2.4">	

	    
	<welcome-file-list>
		        <welcome-file>index.html</welcome-file>
  	  </welcome-file-list>

    <servlet>
  	
  	<servlet>
	    <display-name>AddItemServlet</display-name>
	        <servlet-name>AddItemServlet</servlet-name>
	        <servlet-class>org.apache.geronimo.samples.inventory.web.AddItemServlet</servlet-class>
    	</servlet>
  	  <servlet>
	        <display-name>IssueingServlet</display-name>
	        <servlet-name>IssueingServlet</servlet-name>
	        <servlet-class>org.apache.geronimo.samples.inventory.web.IssueingServlet</servlet-class>
	    </servlet>
	    <servlet>
	        <display-name>RecievingServlet<name>ReceivingServlet</display-name>
	        <servlet-name>RecievingServlet<name>ReceivingServlet</servlet-name>
	        <servlet-class>org.apache.geronimo.samples.inventory.web.RecievingServlet<ReceivingServlet</servlet-class>
	    </servlet>

  	
  	<servlet-mapping>
	        <servlet-name>AddItemServlet</servlet-name>
	        <url-pattern>/add_item</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
	        <servlet-name>IssueingServlet</servlet-name>
	        <url-pattern>/issue</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
	        <servlet-name>RecievingServlet<name>ReceivingServlet</servlet-name>
	        <url-pattern>/recv</url-pattern>
    </servlet-mapping>
    
    <!-- reference name exposed as a datasource -->
    <resource-ref>
    	    <res-ref-name>jdbc/InventoryDS</res-ref-name>
    	    <res-type>javax.sql.DataSource</res-type>
        	<res-auth>Container</res-auth>
    	    <res-sharing-scope>Shareable</res-sharing-scope>
   	 </resource-ref>
    
</web-app>

geronimo-application.xml tells the application that there is a database pool that needs to be deployed as well. The db pool is defined in InventoryPool.xml and the driver that is needs in order to be deployed is the tranql-connector-ra-1.3.rar file--these two files will reside on the top level layer of the resultant EAR file.

<?xml version="1.0" encoding="UTF-8"?>
<application xmlns="http://geronimo.apache.org/xml/ns/j2ee/application-2.0">

    <dep:environment xmlns:dep="http://geronimo.apache.org/xml/ns/deployment-1.2">
        <dep:moduleId>
            <dep:groupId>org.apache.geronimo.samples</dep:groupId>
            <dep:artifactId>inventory-ear</dep:artifactId>
            <dep:version>2.1</dep:version>
            <dep:type>ear</dep:type>
        </dep:moduleId>
    </dep:environment>
	<module>
		<connector>tranql-connector-ra-1.3.rar</connector>
		<alt-dd>InventoryPool.xml</alt-dd>
	</module>
</application>

Next important phase of the application is accessing defined datasource from the source code. This part is handled by the DBManager class.

package org.apache.geronimo.samples.inventory.util;

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 DBManager {
	
	public static Connection getConnection(){
		Connection con = null;

		try {
			Context context = new InitialContext();
			DataSource ds = (DataSource)context.lookup("java:comp/env/jdbc/InventoryDS");
			con = ds.getConnection();
		} catch (NamingException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return con;
	}

}

Sample Database

The sample database that is being used to demonstrate this application is in-built Derby database. The name of the sample database is InventoryDB and it consists of two tables, namely ITEM and ITEM_MASTER. The fields for each of these tables are described below.

...

The ITEM table stores the data related to the items while ITEM_MASTER stores the quantity in hand of each item.

Tools used

The tools used for developing and building the Inventory sample application are:

Apache Derby

Apache Derby, an Apache DB subproject, is a relational database implemented in Java. Its footprint is so small you can easily embed it in any Java-based solution. In addition to its embedded framework, Derby supports a more familiar client/server framework with the Derby Network Server.
http://db.apache.org/derby/index.html

Apache Maven 2

Maven is a popular open source build tool for enterprise Java projects, designed to take much of the hard work out of the build process. Maven uses a declarative approach, where the project structure and contents are described, rather than the task-based approach used in Ant or in traditional make files, for example. This helps enforce company-wide development standards and reduces the time needed to write and maintain build scripts. The declarative, lifecycle-based approach used by Maven 1 is, for many, a radical departure from more traditional build techniques, and Maven 2 goes even further in this regard. Maven 2 can be download from the following URL:
http://maven.apache.org

Configuring, building and deploying

Currently this sample application is available from our subversion repository, use the following svn command to retrieve the content:

svn co http://svn.apache.org/repos/asf/geronimo/samples/branches/2.1/samples/inventory/Image Removed inventory_home

A directory named inventory_home will be created when you check out from the source, you can choose a directory name and location convenient to you. We will generically refer to this directory as <sample_home>.

Configuring

Configuration of the application consists of creating the database and defining the connection pool to access it.

Creating and Populating Database

After starting Apache Geronimo log into the console and follow the given steps to create the InventoryDB database.

1. Select DB Manager link from the Console Navigation panel on the left.
2. Give the database name as InventoryDB and click Create button.
3. Select InventoryDB to the Use DB field.
4. Open InventoryDB.sql in the <sample_home>/inventory-ear/src/main/resources directory from a text editor.
5. Paste the content InventoryDB.sql to the SQL Commands text area and press Run SQL button.

...

...

item

...

Building

Inventory application comes with an pom.xml script to help users to build from source code. Use the command prompt to navigate into the inventory directory and just give mvn install command to build. It will create the inventory-ear-2.1-SNAPSHOT.ear file under the <sample_home> directory. Now, you are ready to deploy Inventory web application in to the Geronimo Application server.

Deploying

Deploying sample application is pretty straight forward as we are going to use the Geronimo Console.

...

...

Testing of the Sample Application

To test the sample application, open a browser and type http://localhost:8080/inventory^{Image Removed}. The Welcome page of Inventory application which is acts as a notice board will be loaded.

...

The user can directly access Add Items, Receive Goods and Issue Goods functionalities from the Welcome page.

Summary

This article has shown you how to use JDBC features inside the Geronimo Application Server. You followed step-by-step instructions to build, deploy and test a sample application to elaborate these features.

The highlights of this article are:

...

.