# Discovery v5 *Dmitrii Shmatko* ### .. slides: https://hackmd.io/@0klO-1bXTU-4eDnt-ZnrHg/d#/ --- ## Who am I? - Dmitrii Shmatko from Harmony team - Last 5 years: Java, Ethereum, Python, Node.js, Financial apps - Before: small IT enterprenuer, development management, databases ---  --- ### Specification Read full [Discovery v5 specification](https://github.com/ethereum/devp2p/blob/master/discv5/discv5.md)  What's node ID?  --- ### Module first!  --- ### Module structure  --- ### Client/Server ```java= /** * Netty-specific extension of {@link DiscoveryServer}. * Made to reuse server channel for client. */ public interface NettyDiscoveryServer extends DiscoveryServer { /** * Reuse Netty server channel with client, * so you are able to send packets from the same port */ CompletableFuture<Void> useDatagramChannel( Consumer<NioDatagramChannel> consumer); } ``` --- ### Data flow Pipeline setup: ```java= incomingPipeline .addHandler(new IncomingDataPacker()) .addHandler(new WhoAreYouAttempt(homeNode.getNodeId())) .addHandler(new WhoAreYouSessionResolver(authTagRepo)) .addHandler(new UnknownPacketTagToSender(homeNode)) .addHandler(nodeIdToSession) .addHandler(new UnknownPacketTypeByStatus()) .addHandler(new NotExpectedIncomingPacketHandler()) .addHandler(new WhoAreYouPacketHandler(outgoingPipeline, taskScheduler)) ``` start: ```java= incomingPipeline.build(); Flux.from(discoveryServer.getIncomingPackets()) .subscribe(incomingPipeline::push); ``` --- ### Handler  --- ### Outgoing pipeline setup: ```java= outgoingPipeline .addHandler(new OutgoingParcelHandler(outgoingSink)) .addHandler(new NodeSessionRequestHandler()) .addHandler(nodeIdToSession) .addHandler(new NewTaskHandler()) .addHandler(new NextTaskHandler(outgoingPipeline, taskScheduler)); ``` usage: ```java= public void sendOutgoing(Packet packet) { logger.trace(() -> String.format("Sending outgoing packet %s in session %s", packet, this)); outgoing.accept(packet); } ``` --- ### ENR  --- ### ENR Specification as defined in [EIP-778](https://eips.ethereum.org/EIPS/eip-778)  --- ### NodeSession  --- ### Discovery Manager  --- ### Tests  --- ### Interop test   --- ### Plans - minor polishing and finish - implement topics - topics research --- ### Thank you! You can find discovery implementation [on Github](https://github.com/harmony-dev/beacon-chain-java/pull/189) ### Questions ?!