Distributed Data Management in Oracle Coherence

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This article shows how to provide distributed(partitioned) data management by using Oracle Coherence. In below sample application, a new cluster named OTV has been created and a cache object nameduser-map has been distributed between two members of the cluster.

Used Technologies :

JDK 1.6.0_21
Maven 3.0.2
Coherence 3.7.0
SolarisOS 5.10

STEP 1 : CREATE MAVEN PROJECT

A maven project is created as below. (It can be created by using Maven or IDE Plug-in).

STEP 2 : DOWNLOAD COHERENCE PACKAGE

Coherence package is downloaded viahttp://www.oracle.com/technetwork/middleware/coherence/downloads/index.html

STEP 3 : LIBRARIES

Firstly, Coherence library is installed to Local Maven Repository and its description is added to pom.xml as below. Also, if maven is not used, coherence.jar file can be added to classpath.

< dependency >
    < groupId >com.tangosol groupId >
    < artifactId >coherence artifactId >
    < version >3.7.0 version >
dependency >

Below plugin can be used to create runnable-jar.

< plugin >
    < groupId >org.apache.maven.plugins groupId >
    < artifactId >maven-assembly-plugin artifactId >
    < configuration >
        < descriptorRefs >
            < descriptorRef >jar-with-dependencies descriptorRef >
        descriptorRefs >
        < archive >
            < manifest >
                < mainClass >com.otv.exe.TestCacheExecutor mainClass >
            manifest >
        archive >
    configuration >
    < executions >
        < execution >
            < phase >package phase >
            < goals >
                < goal >single goal >
            goals >
        execution >
    executions >
plugin >

STEP 4 : CREATE otv-coherence-cache-config.xml

otv-coherence-cache-config.xml contains caching-schemes(distributed or replicated) and caching-scheme-mapping configuration. Created all cache mappings should be added to coherence-cache-config.xml.

xml version = "1.0" ?>

< cache-config xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
    xmlns = "http://xmlns.oracle.com/coherence/coherence-cache-config"
    xsi:schemaLocation="http://xmlns.oracle.com/coherence/coherence-cache-config
   coherence-cache-config.xsd">

    < caching-scheme-mapping >
        < cache-mapping >
            < cache-name >user-map cache-name >
            < scheme-name >MapDistCache scheme-name >
        cache-mapping >
    caching-scheme-mapping >

    < caching-schemes >
        < distributed-scheme >
            < scheme-name >MapDistCache scheme-name >
            < service-name >MapDistCache service-name >
            < backing-map-scheme >
                < local-scheme >
                    < unit-calculator >BINARY unit-calculator >
                local-scheme >
            backing-map-scheme >
            < autostart >true autostart >
        distributed-scheme >
    caching-schemes >

cache-config >

STEP 5 : CREATE tangosol-coherence-override.xml

tangosol-coherence-override.xml contains cluster, member-identity and configurable-cache-factoryconfiguration. Also below configuration xml file show first member of the cluster.

tangosol-coherence-override.xml for first member of the cluster :

xml version = '1.0' ?>

< coherence xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xmlns = "http://xmlns.oracle.com/coherence/coherence-operational-config"
   xsi:schemaLocation = "http://xmlns.oracle.com/coherence/coherence-operational-config coherence-operational-config.xsd" >

   < cluster-config >

      < member-identity >
         < cluster-name >OTV cluster-name >

         < role-name >OTV1 role-name >
      member-identity >

      < unicast-listener >
          < well-known-addresses >
            < socket-address id = "1" >

              < address >x.x.x.x address >
              < port >8089 port >
            socket-address >
            < socket-address id = "2" >

              < address >y.y.y.y address >
              < port >8089 port >
            socket-address >
          well-known-addresses >


          < machine-id >OTV1 machine-id >

          < address >x.x.x.x address >
          < port >8089 port >
          < port-auto-adjust >true port-auto-adjust >
      unicast-listener >

   cluster-config >

   < configurable-cache-factory-config >
      < init-params >
         < init-param >
            < param-type >java.lang.String param-type >
            < param-value system-property = "tangosol.coherence.cacheconfig" >
              otv-coherence-cache-config.xml
            param-value >
         init-param >
      init-params >
   configurable-cache-factory-config >

coherence >

tangosol-coherence-override.xml for second member of the cluster :

xml version = '1.0' ?>

< coherence xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xmlns = "http://xmlns.oracle.com/coherence/coherence-operational-config"
   xsi:schemaLocation = "http://xmlns.oracle.com/coherence/coherence-operational-config coherence-operational-config.xsd" >

   < cluster-config >

      < member-identity >
         < cluster-name >OTV cluster-name >

         < role-name >OTV2 role-name >
      member-identity >

      < unicast-listener >

          < well-known-addresses >
            < socket-address id = "1" >

              < address >x.x.x.x address >
              < port >8089 port >
            socket-address >
            < socket-address id = "2" >

              < address >y.y.y.y address >
              < port >8089 port >
            socket-address >
          well-known-addresses >


          < machine-id >OTV2 machine-id >

          < address >y.y.y.y address >
          < port >8089 port >
          < port-auto-adjust >true port-auto-adjust >

      unicast-listener >

   cluster-config >

   < configurable-cache-factory-config >
      < init-params >
         < init-param >
            < param-type >java.lang.String param-type >
            < param-value system-property = "tangosol.coherence.cacheconfig" >
              otv-coherence-cache-config.xml param-value >
         init-param >
      init-params >
   configurable-cache-factory-config >

coherence >

STEP 6 : CREATE USER BEAN

A new User bean is created. This bean will be distributed between two node in OTV cluster. For serializing,java.io.Serializable interface has been implemented but PortableObject can be implemented for better performance.

package com.otv.user;

import java.io.Serializable;

/**
 * @author onlinetechvision.com
 * @since 9 Oct 2011
 * @version 1.0.0
 *
 */
public class User implements Serializable {

    private static final long serialVersionUID = 1L;
    private String name;
    private String surname;

    public User(String name, String surname) {
        this .name = name;
        this .surname = surname;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this .name = name;
    }

    public String getSurname() {
        return surname;
    }

    public void setSurname(String surname) {
        this .surname = surname;
    }

    @Override
    public String toString() {
        StringBuffer strBuff = new StringBuffer();
        strBuff.append( "name : " ).append(name);
        strBuff.append( ", surname : " ).append(surname);
        return strBuff.toString();
    }
}

STEP 7 : CREATE CACHE CLASS

A new TestCache Class is created. This class initializes distributed(patitioned) data management and creates a cache object named user-map.

package com.otv;

import org.apache.log4j.Logger;

import com.otv.listener.UserMapListener;
import com.tangosol.net.CacheFactory;
import com.tangosol.net.NamedCache;

/**
 * @author onlinetechvision.com
 * @since 9 Oct 2011
 * @version 1.0.0
 *
 */
public class TestCache {

    private static Logger log = Logger.getLogger(TestCache. class );
    private static TestCache instance = null ;
    private NamedCache cache = null ;
    private static final String USER_MAP = "user-map" ;
    private static final long LOCK_TIMEOUT = - 1 ;

    public TestCache() {
        setCache(CacheFactory.getCache(USER_MAP));
        getCache().addMapListener( new UserMapListener());
    }

    public static TestCache getInstance() {
        if (instance == null ) {
            instance = new TestCache();
        }
        return instance;
    }

    public static void setInstance(TestCache instance) {
        TestCache.instance = instance;
    }

    public NamedCache getCache() {
        return cache;
    }

    public void setCache(NamedCache cache) {
        this .cache = cache;
    }

    public void addToCache(Object key, Object value) {
        // key is locked
        getCache().lock(key, LOCK_TIMEOUT);
        try {
            // application logic
            getCache().put(key, value);
        } finally {
            // key is unlocked
            getCache().unlock(key);
        }
    }

    public void deleteFromCache(Object key) {
        // key is locked
        getCache().lock(key, LOCK_TIMEOUT);
        try {
            // application logic
            getCache().remove(key);
        } finally {
            // key is unlocked
            getCache().unlock(key);
        }
    }
}

STEP 8 : CREATE UserMapListener IMPL CLASS

A new UserMapListener class is created. This listener receives distributed user-map events.

package com.otv.listener;

import org.apache.log4j.Logger;

import com.tangosol.util.MapEvent;
import com.tangosol.util.MapListener;

/**