RSocket is a binary protocol for use on byte stream transports such as TCP, WebSockets, and Aeron.

It enables the following symmetric interaction models via async message passing over a single connection:

Programming language: Java
License: Apache License 2.0
Tags: Networking     Reactive Libraries     API    

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RSocket is a binary protocol for use on byte stream transports such as TCP, WebSockets, and Aeron.

It enables the following symmetric interaction models via async message passing over a single connection:

  • request/response (stream of 1)
  • request/stream (finite stream of many)
  • fire-and-forget (no response)
  • event subscription (infinite stream of many)

Learn more at http://rsocket.io

Build and Binaries

Build Status

⚠️ The master branch is now dedicated to development of the 1.2.x line.

Releases and milestones are available via Maven Central.


repositories {
    maven { url 'https://repo.spring.io/milestone' }  // Reactor milestones (if needed)
dependencies {
    implementation 'io.rsocket:rsocket-core:1.2.0-SNAPSHOT'
    implementation 'io.rsocket:rsocket-transport-netty:1.2.0-SNAPSHOT'

Snapshots are available via [oss.jfrog.org](oss.jfrog.org) (OJO).


repositories {
    maven { url 'https://maven.pkg.github.com/rsocket/rsocket-java' }
    maven { url 'https://repo.spring.io/snapshot' }  // Reactor snapshots (if needed)
dependencies {
    implementation 'io.rsocket:rsocket-core:1.2.0-SNAPSHOT'
    implementation 'io.rsocket:rsocket-transport-netty:1.2.0-SNAPSHOT'


Install the google-java-format in Intellij, from Plugins preferences. Enable under Preferences -> Other Settings -> google-java-format Settings

Format automatically with

$./gradlew goJF


Frames can be printed out to help debugging. Set the logger io.rsocket.FrameLogger to debug to print the frames.


Trivial Client

package io.rsocket.transport.netty;

import io.rsocket.Payload;
import io.rsocket.RSocket;
import io.rsocket.core.RSocketConnector;
import io.rsocket.transport.netty.client.WebsocketClientTransport;
import io.rsocket.util.DefaultPayload;
import reactor.core.publisher.Flux;

import java.net.URI;

public class ExampleClient {
    public static void main(String[] args) {
        WebsocketClientTransport ws = WebsocketClientTransport.create(URI.create("ws://rsocket-demo.herokuapp.com/ws"));
        RSocket clientRSocket = RSocketConnector.connectWith(ws).block();

        try {
            Flux<Payload> s = clientRSocket.requestStream(DefaultPayload.create("peace"));

            s.take(10).doOnNext(p -> System.out.println(p.getDataUtf8())).blockLast();
        } finally {

Zero Copy

By default to make RSocket easier to use it copies the incoming Payload. Copying the payload comes at cost to performance and latency. If you want to use zero copy you must disable this. To disable copying you must include a payloadDecoder argument in your RSocketFactory. This will let you manage the Payload without copying the data from the underlying transport. You must free the Payload when you are done with them or you will get a memory leak. Used correctly this will reduce latency and increase performance.

Example Server setup

RSocketServer.create(new PingHandler())
        // Enable Zero Copy

Example Client setup

RSocket clientRSocket =
            // Enable Zero Copy

Bugs and Feedback

For bugs, questions and discussions please use the Github Issues.


Copyright 2015-2020 the original author or authors.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at


Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

*Note that all licence references and agreements mentioned in the RSocket README section above are relevant to that project's source code only.