Question

My application is based on the hibernate to fetched data from a mysql server. This mysql server is replicated to another mysql server instance. Today, I got a downtime as the primary database server was gone down without any notice. To avoid any future accidental problem, I am planing to add a functionality that will enable system to connect to secondary database if it finds the primary down.

Is there exists a way by which, I can leverage hibernate library to enable this functionality?

Answer 1

I have created following class after getting an idea form this thread
It seems to be working well. I don’t know if this is a good approach at all.

package com.vsd.server.hibernate;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

import org.apache.commons.lang.StringUtils;
import org.hibernate.HibernateException;
import org.hibernate.connection.C3P0ConnectionProvider;

public class FailoverConnectionProvider extends C3P0ConnectionProvider {

    String password;
    String username;
    String connectionString;
    String failover_connstring;

    @Override
    public Connection getConnection() throws SQLException {

        Connection conn = null;

        try {
            conn = DriverManager.getConnection(connectionString, username, password);
        } catch (Exception ex) {
            conn = DriverManager.getConnection(failover_connstring, username, password);
        }

        if(conn == null){
            throw new IllegalStateException("Database connection was not initialized");
        }

        return conn;

    }

    @Override
    public void configure(Properties properties) throws HibernateException {
        failover_connstring = properties.getProperty("hibernate.connection.failover.url");

        if (StringUtils.isBlank(connectionString)
                && StringUtils.isBlank(failover_connstring)
                && StringUtils.isBlank(username)
                && StringUtils.isBlank(password)) {
            throw new IllegalStateException("Unable to initialize connection provider for hibernate");
        }
    }
}