/**
 * This class represents a DAO factory for a SQL database. You can use {@link #getInstance(String)}
 * to obtain a new instance for the given database name. The specific instance returned depends on
 * the properties file configuration. You can obtain DAO's for the DAO factory instance using the
 * DAO getters.
 * <p>
 * This class currently requires a properties file named 'dao.properties' in the classpath with among others
 * the following properties:
 * <pre>
 * name.url *
 * name.driver
 * name.username
 * name.password
 * </pre>
 * Those marked with * are required, others are optional and can be left away or empty. Only the
 * username is required when any password is specified.
 * <ul>
 * <li>The 'name' must represent the database name in {@link #getInstance(String)}.</li>
 * <li>The 'name.url' must represent either the JDBC URL or JNDI name of the database.</li>
 * <li>The 'name.driver' must represent the full qualified class name of the JDBC driver.</li>
 * <li>The 'name.username' must represent the username of the database login.</li>
 * <li>The 'name.password' must represent the password of the database login.</li>
 * </ul>
 * If you specify the driver property, then the url property will be assumed as JDBC URL. If you
 * omit the driver property, then the url property will be assumed as JNDI name. When using JNDI
 * with username/password preconfigured, you can omit the username and password properties as well.
 * <p>
 * Here are basic examples of valid properties for a database with the name 'javabase':
 * <pre>
 * javabase.jdbc.url = jdbc:mysql://localhost:3306/javabase
 * javabase.jdbc.driver = com.mysql.jdbc.Driver
 * javabase.jdbc.username = java
 * javabase.jdbc.password = d$7hF_r!9Y
 * </pre>
 * <pre>
 * javabase.jndi.url = jdbc/javabase
 * </pre>
 * Here is a basic use example:
 * <pre>
 * DAOFactory javabase = DAOFactory.getInstance("javabase.jdbc");
 * UserDAO userDAO = javabase.getUserDAO();
 * </pre>
 *
 * @author Leon Merten
 */