Documentation Version: 3.3-EA - Publication Date : May 22, 2014

Cluster Utilities

Cluster Interface

Hazelcast allows you to register for membership events to get notified when members added or removed. You can also get the set of cluster members.

import com.hazelcast.core.*;
import com.hazelcast.config.Config;

Config cfg = new Config();
HazelcastInstance hz = Hazelcast.newHazelcastInstance(cfg);
Cluster cluster = hz.getCluster();
cluster.addMembershipListener(new MembershipListener(){
    public void memberAdded(MembershipEvent membersipEvent) {
        System.out.println("MemberAdded " + membersipEvent);
    }

    public void memberRemoved(MembershipEvent membersipEvent) {
        System.out.println("MemberRemoved " + membersipEvent);
    }
});

Member localMember  = cluster.getLocalMember();
System.out.println ("my inetAddress= " + localMember.getInetAddress());

Set setMembers  = cluster.getMembers();
for (Member member : setMembers) {
    System.out.println ("isLocalMember " + member.localMember());
    System.out.println ("member.inetaddress " + member.getInetAddress());
    System.out.println ("member.port " + member.getPort());
}

Cluster Wide ID Generator

Hazelcast IdGenerator creates cluster wide unique IDs. Generated IDs are long type primitive values between 0 and Long.MAX_VALUE. ID generation occurs almost at the speed of AtomicLong.incrementAndGet(). Generated IDs are unique during the life cycle of the cluster. If the entire cluster is restarted, IDs start from 0 again or you can initialize to a value.

import com.hazelcast.core.IdGenerator;
import com.hazelcast.core.Hazelcast;

Config cfg = new Config();
HazelcastInstance hz = Hazelcast.newHazelcastInstance(cfg);
IdGenerator idGenerator = hz.getIdGenerator("customer-ids");
idGenerator.init(123L); //Optional
long id = idGenerator.newId();