V3 How do we connect two nodes?

[davidroman0O]

I've been looking at the v3 codebase and played with the ergo_examples repo on the v3 branch, there are lot of examples on how to setup one node with all the tooling ergo is providing (udp, tcp, http, web server, etc), so far so good!

I know you're going to release the documentation soon but in the same time I would like to continue playing with it!

I saw there is a "registrar" that is supposed to help to connect nodes, I'm a little bit confused, I tried but i end up with err being filled for various reasons, I'm pretty sure i'm missing one little thing!

Do you have a simple code snippet of a simple ping-pong between two different runtimes? 🙏

[davidroman0O]

Just posting what I had, to test that ping-pong, what not supported means in that case? Do I miss a hierarchy permission thing?

ping

package main

import (
	"fmt"
	"log"
	"time"

	"ergo.services/ergo"
	"ergo.services/ergo/act"
	"ergo.services/ergo/gen"
)

type Ping struct {
	act.Actor
}

func (p *Ping) HandleCall(from gen.PID, ref gen.Ref, request any) (any, error) {
	switch request.(type) {
	case string:
		log.Println("Ping received pong, sending ping")
		return "ping", nil
	}
	return nil, fmt.Errorf("unexpected request: %#v", request)
}

func (p *Ping) HandleMessage(from gen.PID, message any) error {
	switch message.(type) {
	case string:
		log.Println("Ping received pong, sending ping")
		_, err := p.Call(from, "ping")
		return err
	}
	return fmt.Errorf("unexpected message: %#v", message)
}

func NewPing() gen.ProcessBehavior {
	return &Ping{}
}

func main() {
	node, err := ergo.StartNode("ping@localhost", gen.NodeOptions{
		Network: gen.NetworkOptions{
			Cookie:             "cookie",
			InsecureSkipVerify: true,
		},
	})
	if err != nil {
		log.Fatalf("Failed to start ping: %v", err)
	}
	defer node.Stop()

	node.Spawn(NewPing, gen.ProcessOptions{})

	go func() {
		time.Sleep(1 * time.Second)
		if err = node.Send("pong@localhost", "ping"); err != nil {
			fmt.Printf("Unable to send message to node '%s': %s\n", "pong@localhost", err)
			return
		}
	}()

	node.Wait()
}

pong

package main

import (
	"fmt"
	"log"

	"ergo.services/ergo"
	"ergo.services/ergo/act"
	"ergo.services/ergo/gen"
)

type Pong struct {
	act.Actor
}

func (p *Pong) HandleCall(from gen.PID, ref gen.Ref, request any) (any, error) {
	switch request.(type) {
	case string:
		log.Println("Pong received ping, sending pong")
		return "pong", nil
	}
	return nil, fmt.Errorf("unexpected request: %#v", request)
}

func (p *Pong) HandleMessage(from gen.PID, message any) error {
	switch message.(type) {
	case string:
		log.Println("Pong received ping, sending pong")
		_, err := p.Call(from, "pong")
		return err
	}
	return fmt.Errorf("unexpected message: %#v", message)
}

func NewPong() gen.ProcessBehavior {
	return &Pong{}
}

func main() {
	node, err := ergo.StartNode("pong@localhost", gen.NodeOptions{
		Network: gen.NetworkOptions{
			Cookie:             "cookie",
			InsecureSkipVerify: true,
		},
	})
	if err != nil {
		log.Fatalf("Failed to start pong: %v", err)
	}
	defer node.Stop()

	node.Spawn(NewPong, gen.ProcessOptions{})

	node.Wait()
}

[halturin]

Things that need to be fixed in your example:

1. Use SpawnRegister to be able to send messages by the process name. for example
   node.SpawnRegister("pong_process", NewPong, gen.ProcessOptions{})

2. Incorrect process name "pong@localhost". Use gen.ProcessID for sending messages to the remote process by name
   node.Send(gen.ProcessID{Name: "pong_process", Node: "pong@localhost"}, message)
   that was the reason of your "not supported" error. Node couldn't recognize the destination in node.Send("pong@localhost", "ping"). Destination must be:
   

   You can use node.Send(gen.Atom("pong_process"), message) only if that process was spawned on the same node.

Beside that...

• You are sending messages using Send(...) method of gen.Node interface. It uses CorePID as a sender which is a virtual process identifier with no process under the hood (no mailbox for the messages, no handlers etc).
• You will get the gen.ErrTimeout in p.Call(...) since no real process with that pid.

Please, take a look at "call" example https://github.com/ergo-services/examples/tree/v300. It does exactly what you want:

[davidroman0O]

Ooooh ok it works now, i see!

Oh I completely missed that line remote := gen.ProcessID{Name: "b", Node: "nodeB@localhost"} on your example! 🤦‍♂️

Thank you for your answer, very instructive! I can't wait to read the doc!

Now I'm curious to explore what's that alias thing! 😄
I will continue to read the code and explore until i have thing ive missed or don't understand

Thanks again!