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Version: 0.8

Membership Management

On this page we show you how to integrate the gossip-based membership management protocol CYCLON. The CYCLON protocol generates a unstructured overlay sharing similarities with a random graph. Beside membership management this protocol can be used for resource discovery (e.g., by performing a random walk).

If you would like to learn mor about this protocl, please refer to this paper:

Voulgaris, S., Gavidia, D. & van Steen, M. CYCLON: Inexpensive Membership Management for Unstructured P2P Overlays. J Netw Syst Manage 13, 197–217 (2005).

To use this protocol, you have to use the bootstrapping interface, where you have to customize the server channel's ChannelInitializer. Below you find a code snippet with a customized initializer including the Chord related handlers. The CyclonView object passed to the handlers contains the local (partial) view of the network. By calling view.getNeighbors() you will get a list of currently known neighbors and their corresponding addresses. Please refer to the above-mentioned paper for choosing proper view size and shuffle size values.

import io.netty.bootstrap.ServerBootstrap;
import org.drasyl.handler.membership.cyclon.*;
import org.drasyl.identity.*;
import java.util.Set;

public class MembershipManagement {
public static void main(final String[] args) {
final Identity identity = /* code */;
final int viewSize = 8; // maximum size of peers in own view
final int shuffleSize = 4; // maximum number of peers to shuffle
final int shuffleInterval = 10_000; // shuffle every 10 seconds
final Set<DrasylAddress> initialNeighbors = Set.of(/* code */);
final CyclonView view = CyclonView.ofKeys(viewSize, initialNeighbors);

final ServerBootstrap b = new ServerBootstrap()
.group(new NioEventLoopGroup())
.handler(new TraversingDrasylServerChannelInitializer(identity, 0) {
protected void initChannel(final DrasylServerChannel ch) {

final ChannelPipeline p = ch.pipeline();

// (de)serialize cyclon messages
p.addLast(new CyclonCodec());
// requests shuffle with random neighbor
p.addLast(new CyclonShufflingClientHandler(shuffleSize, shuffleInterval, view));
// responses to shuffle requests
p.addLast(new CyclonShufflingServerHandler(shuffleSize, view));
.childHandler(/* code */);


A fully working example can be found here: CyclonMembershipManagement