This sample application demonstrates how you can run TransactionsEssentials in a web application by fully embedding it in the WAR file.

It is a simple blueprint application that shows and updates the content of a single Derby database.

Download the sample application here:

• dbtest.war

To install it, simply copy the WAR file in Tomcat's webapps folder. You can then access it via this URL: http://localhost:8080/dbtest/.

Notes

• This demo uses an embedded Derby database. If it doesn't exist a new one is created in TOMCAT_HOME/work or else, the existing one is reused.
• The transactions logs and debug logs are stored in TOMCAT_HOME/work.

Configuration files

context.xml

<Context antiJARLocking="true">

  <Resource name="jdbc/myDB" auth="Container" type="com.atomikos.jdbc.SimpleDataSourceBean"
            factory="org.apache.naming.factory.BeanFactory"
            uniqueResourceName="jdbc/myDB"
            xaDataSourceClassName="org.apache.derby.jdbc.EmbeddedXADataSource"
            exclusiveConnectionMode="true"
            connectionPoolSize="3"
            connectionTimeout="10"
            xaDataSourceProperties="databaseName=../work/users1;createDatabase=create"/>

  <Transaction factory="com.atomikos.icatch.jta.UserTransactionFactory" />

</Context> 

web.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
 <!DOCTYPE web-app PUBLIC
   "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
   "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>
  <listener>
    <listener-class>foo.ContextListener</listener-class>
  </listener>

  <resource-env-ref>
    <resource-env-ref-name>jdbc/myDB</resource-env-ref-name>
    <resource-env-ref-type>javax.sql.DataSource</resource-env-ref-type>
  </resource-env-ref>

  <welcome-file-list>
    <welcome-file>test.jsp</welcome-file>
  </welcome-file-list>
</web-app>

jta.properties

com.atomikos.icatch.service=com.atomikos.icatch.standalone.UserTransactionServiceFactory
com.atomikos.icatch.log_base_dir=../work
com.atomikos.icatch.output_dir=../work
com.atomikos.icatch.console_log_level=DEBUG

JSP sources

dbtest.jsp

<html>
  <head>
    <title>DB Test</title>
  </head>
  <body>

    <%
    String completion = request.getParameter("completion");
    foo.DBTest test = new foo.DBTest();
    test.init(completion);
    %>
    <h2>Transaction completion</h2>
    Transaction completion is :<strong><%= completion %></strong>

    <h2>Results</h2>
    Int stored in JDBC : <strong><%= test.getFoo() %></strong><br />

    <hr />

    <form action="test.jsp" method="get">
      <input type="radio" name="completion" value="commit" checked="true"> Commit<BR>
      <input type="radio" name="completion" value="rollback">Rollback<BR>
      <button type="submit">Completion</button>
    </form>
  </body>
</html>

Java sources

Context Listener.java

package foo;

import javax.servlet.ServletContextListener;
import javax.servlet.ServletContextEvent;

import com.atomikos.icatch.jta.UserTransactionManager;

public class ContextListener implements ServletContextListener {

    private UserTransactionManager utm;

    public void contextInitialized(ServletContextEvent event) {
        try {
            utm = new UserTransactionManager();
            utm.init();
            System.out.println("initialized transaction manager");
        }
        catch (Exception ex) {
            utm = null;
            throw new RuntimeException("cannot initialize UserTransactionManager", ex);
        }
    }

    public void contextDestroyed(ServletContextEvent event) {
        if (utm != null) {
            utm.close();
            System.out.println("shut down transaction manager");
        }
    }
}

DBTest.java

package foo;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.SQLException;
import java.sql.Connection;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;
import javax.transaction.UserTransaction;

public class DBTest{

    int foo = -1;
    // value stored in DB

    public void init(String completion) {
        try{
            Context ctx = new InitialContext();

            // JDBC stuff
            DataSource ds =
                (DataSource)ctx.lookup("java:comp/env/jdbc/myDB");
            ensureTableExists(ds);

            UserTransaction ut = (UserTransaction)ctx.lookup("java:comp/UserTransaction");

            Connection conn = ds.getConnection();

            System.out.println("<<< beginning the transaction >>>");
            ut.begin();

             // JDBC statements
             Statement stmt = conn.createStatement();
             ResultSet rst =
                 stmt.executeQuery("select id, foo from testdata");
             if(rst.next()) {
                 foo=rst.getInt(2);
             }
             System.out.println("foo = "+ foo +" (before completion)");

             PreparedStatement pstmt = conn.prepareStatement("update testdata set foo=? where id=1");
             pstmt.setInt(1,++foo);
             pstmt.executeUpdate();

              if (completion != null && completion.equals("commit")) {
                  System.out.println("<<< committing the transaction >>>");
                  ut.commit();
              } else {
                  System.out.println("<<< rolling back the transaction >>>");
                  ut.rollback();
              }

             // we set foo to the value stored in the DB
             rst =
                 stmt.executeQuery("select id, foo from testdata");
             if(rst.next()) {
                 foo=rst.getInt(2);
             }
             System.out.println("foo = "+ foo +" (after completion)");

             conn.close();
             System.out.println("<<< done >>>");
        }catch(Exception e) {
            System.out.print("DBTest >> ");
            e.printStackTrace();
        }
    }

    public String getFoo() { return ""+foo; }

    private void ensureTableExists(DataSource ds) throws Exception {
        Connection c = ds.getConnection();

        try {
            Statement stmt = c.createStatement();
            stmt.executeUpdate("create table testdata (id integer not null primary key, foo integer)");
            stmt.executeUpdate("insert into testdata values(1, 1)");
            stmt.close();
            c.commit();
            System.out.println("<<< created table >>>");
        }
        catch (SQLException ex) {
            // ignore
        }

        c.close();
    }
}

Required libs

JAR name	Source
atomikos-util.jar	TransactionsEssentials 3.1.5
derby-10.2.2.0.jar	Derby 10.2.2.0
jta.jar	TransactionsEssentials 3.1.5
transactions-api.jar	TransactionsEssentials 3.1.5
transactions-jta.jar	TransactionsEssentials 3.1.5
transactions.jar	TransactionsEssentials 3.1.5