Load Balancer

Overview

This is Load Balancer library.

How to run

Requirements:

• Java 8
• Maven

To build this project, just type in terminal:

mvn clean install

How to configure Load Balancer using Spring Framework

1. Create persistence.xml file in your \resources\META-INF directory. Next you have to copy below configuration into this file.

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">
    <persistence-unit name="manager1" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
            <property name="hibernate.show_sql" value="true"/>
        </properties>
    </persistence-unit>
</persistence>

2.Create Spring configuration class PersistanceConfig in your config directory
3.Because Spring requires one DataSource specified as Bean, you should create it but it is unnecessery to our library
4.To achieve successful LoadBalancer configuration you need to use LoadBalancerDataSource, DatabaseConfiguration, LoadBalancingStrategy classes and create LoadBalancer class bean.

Class description:
LoadBalancerDataSource class is used to specify database connection details. You must pass driverClassName, url, username, password. By default driverClassName="org.postgresql.Driver", user= "postgres", pass = "", so if you have database with these parameters you need to give just url.
DatabaseConfiguration class is used to specify whole database settings. That includes collection of LoadBalancerDataSources and LoadBalancingStrategy. It has to be passed as an argument in LoadBalancer constructor
LoadBalancingStrategy class is used to specify concrete load balancing strategy. There are two available strategies: EqualDistributionStrategy and RandomStrategy.

Configuration example:

@Configuration
@EnableTransactionManagement
public class PersistenceConfig {

    //Simple DataSource is created because of Spring restrictions
    @Bean
    public DataSource primaryDataSource() {
        BasicDataSource dataSource = new BasicDataSource();
        dataSource.setDriverClassName("org.postgresql.Driver");
        dataSource.setUrl("jdbc:postgresql://192.168.99.100:5432/postgres");
        dataSource.setUsername("postgres");
        dataSource.setPassword("");

        return dataSource;
    }

    @Bean
    public DatabaseConfiguration prepareDatabaseConfiguration(){
        DatabaseConfiguration config = new DatabaseConfiguration.ConfigurationBuilder()
                .dataSources(createLoadBalancerDataSourceList())
                .strategy(new EqualDistributionStrategy())
                .build();
        return config;
    }

    @Bean
    public LoadBalancer getLoadBalancer(){

        LoadBalancer loadBalancer = new LoadBalancerImpl(prepareDatabaseConfiguration());
        return loadBalancer;
    }

    private List<LoadBalancerDataSource> createLoadBalancerDataSourceList() {
        List<LoadBalancerDataSource> list = new LinkedList<>();
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5432/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5433/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5434/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5435/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5436/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5437/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5438/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5439/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5440/postgres")
                .build());
        list.add(new LoadBalancerDataSource.DataSourceBuilder()
                .url("jdbc:postgresql://192.168.99.100:5441/postgres")
                .build());
        return list;
    }
}

Authors

• Mateusz Kuźmik
• Jakub Kacorzyk
• Bartłomiej Łazarczyk
• Szymon Jakóbczyk