Gossip

Gossip protocol is a method for a group of nodes to discover and check the liveliness of a cluster. More information can be found at http://en.wikipedia.org/wiki/Gossip_protocol.

Usage

Maven

<dependency>
  <groupId>net.lvsq</groupId>
  <artifactId>jgossip</artifactId>
  <version>1.3.2</version>
</dependency>

First you need one or more seed members

List<SeedMember> seedNodes = new ArrayLis<>();
SeedMember seed = new SeedMember();
seed.setCluster(cluster);
seed.setIpAddress(ipAddress);
seed.setPort(port);
seedNodes.add(seed);

Then, instantiation a `GossipService` object

GossipService gossipService = new GossipService(cluster,ipAddress, port, id, seedNodes, new GossipSettings(), (member, state) -> {
        //Do anything what you want
    });

Run `GossipService`

gossipService.start();

Stop

gossipService.shutdown();

Get offline nodes

gossipService.getGossipManager().getDeadMembers();

Get online nodes

gossipService.getGossipManager().getLiveMembers();

Settings

gossipInterval - How often (in milliseconds) to gossip list of members to other node(s). Default is 1000ms
networkDelay - Network delay in ms. Default is 200ms
msgService - Which message sync implementation. Default is UDPMsgService.class use UDP protocol to send message, certainly you can extand it.
deleteThreshold - Delete the deadth node when the sync message is not received more than [deleteThreshold] times. Default is 3

Event Listener

Now, we have three kinds of event

GossipState.UP;
GossipState.DOWN;
GossipState.JOIN;

Example

int gossip_port = 60001;
String cluster = "gossip_cluster";

GossipSettings settings = new GossipSettings();
settings.setGossipInterval(1000);

try {
    String myIpAddress = InetAddress.getLocalHost().getHostAddress();
    List<SeedMember> seedNodes = new ArrayList<>();
    SeedMember seed = new SeedMember();
    seed.setCluster(cluster);
    seed.setIpAddress(myIpAddress);
    seed.setPort(60001);
    seedNodes.add(seed);

    gossipService = new GossipService(cluster, myIpAddress, gossip_port, null, seedNodes, settings, (member, state) ->System.out.println("member:" + member + "  state: " + state));
} catch (Exception e) {
    e.printStackTrace();
}
gossipService.start();