org.hibernate.TransactionException: Unable to locate JTA UserTransaction

I am writing my first example for Inserting Record using Hibernate Framework .

To start with I am trying to following instructions given at URL

You can see my code at GIT Hibernate Basic

When calling below piece of code

public Long saveEmployee(Employee emp){
    Session session = new Configuration().configure().buildSessionFactory().openSession();
    session.beginTransaction();
    Long id = (Long) session.save(emp);
    session.getTransaction().commit();
    session.close();
    return id;
}

hibernate.cfg.xml

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
        <!-- Database connection settings -->
            <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
            <property name="connection.url">jdbc:mysql://localhost:3306/test</property>
            <property name="connection.username">root</property>
            <property name="connection.password">root123</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">2</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">false</property>
        <!-- validate | update | create | create-drop -->
        <!-- validate: validate the schema, makes no changes to the database.
        update: update the schema.
        create: creates the schema, destroying previous data.
        create-drop: drop the schema at the end of the session. -->
        <property name="hbm2ddl.auto">validate</property>
 <!-- added as suggested in below answer-->            
<property name="hibernate.transaction.factory_class">org.hibernate.transaction.JTATransactionFactory</property>

        <mapping resource="Employee.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

It throws org.hibernate.TransactionException: Unable to locate JTA UserTransaction

Details :

• I am not deploying the application from any Application server I am running it as plan Java application.
• I am using Hibernate 4.1

Is it neccessary to deploy it in Application Server ?

Whether we have to explicitly specify the JTAUsertransaction in Hibernate 4.1 version?

=============== Update ==============

With
hibernate.transaction.factory_class = org.hibernate.engine.transaction.internal.jdbc.JdbcTransactionFactory Solved this error and I can execute the program .

But I still wanted to know the reason why its not working when using org.hibernate.transaction.JTATransactionFactory