Add dependency

Adding encon’s dependency to your JVM app:

Maven:

<dependencies>
  ...
  <dependency>
    <groupId>io.appulse.encon</groupId>
    <artifactId>encon</artifactId>
    <version>1.6.7</version>
  </dependency>
  ...
</dependencies>

Gradle:

dependencies {
  compile 'io.appulse.encon:encon:1.6.7'
}

Start the Node

import io.appulse.encon.Node;
import io.appulse.encon.Nodes;
import io.appulse.encon.config.NodeConfig;


// Creating node's config.
// For more details - see encon-config project
NodeConfig config = NodeConfig.builder()
    .shortName(true) // true - for local nodes, false (default) - for remote accessable
    .cookie("secret")
    .build();

// Creates, registers in EPMD and starts a new Erlang node
Node node = Nodes.singleNode("echo-node", config);

Create a Mailbox

import io.appulse.encon.mailbox.Mailbox;


Mailbox mailbox = node.mailbox()
    .name("popa") // this is an optional
    .build();

Connect the nodes

NOTICE: You can initiate the connection from either Erlang/Elixir or Java side automatically by sending to a remote name using tuple format {Name, Node} or sending to a remote pid (if you have it).

You can initiate the connection between nodes from Erlang side. To do this, on Erlang side you can use net_adm:ping.

(erlang@localhost)1> net_adm:ping('java@localhost').
pong
(erlang@localhost)2>

Also you could send a message to {Name, Node}, where Node is an atom like 'java@localhost', and Name is a pid or some registered name, which exists on the Java side.

(erlang@localhost)1> {my_process, 'java@localhost'} ! hello.
hello
(erlang@localhost)2>

If the process exists on Java side, its mailbox will receive your message. You can check it from your code using one of the Mailbox methods: receive() or receive(timeout, timeUnit), which can wait eternal or fixed amount of time for another message.

Send message from Java

You can send messages using the family of send methods, which can deliver messages locally or remotely:

  • send(ErlangPid, ErlangTerm) - sends a payload to a remote or local PID;
  • send(String, ErlangTerm) - sends a message to local mailbox of this Node by its name;
  • send(String, String, ErlangTerm) - sends a payload to a remote/local node and mailbox by its names.

To try this, open an Erlang shell and register shell with the name 'shell':

(erlang@localhost)1> erlang:register(shell, self()).
true
(erlang@localhost)2>

Now we can try and send the message from Java (node connection will be established automatically):

import static io.appulse.encon.terms.Erlang.atom;


mailbox.send("erlang@localhost", "shell", atom("hello"));

(erlang@localhost) 1> flush().
Shell got hello
ok
(erlang@localhost) 2>

Receive message in Java

import io.appulse.encon.Node;
import io.appulse.encon.Nodes;
import io.appulse.encon.config.NodeConfig;
import io.appulse.encon.connection.regular.Message;
import io.appulse.encon.mailbox.Mailbox;


public class Main {

  public static void main (String[] args) {
    NodeConfig config = NodeConfig.builder()
        .shortName(true)
        .build();

    Node node = Nodes.singleNode("java@localhost", config);

    Mailbox mailbox = node.mailbox()
        .name("my_process")
        .build();

    Message message = mailbox.receive();
    System.out.println("Incoming message: " + message.getBody().asText());
  }
}

Start erlang node and send a message:

$> erl -sname erlang@localhost
...
(erlang@localhost)1> {my_process, 'java@localhost'} ! hello.