Protocols-and-Streams.md

Protocols & Streams 🗺️

In easyp2p, you communicate by defining Protocols. A protocol is a specific "app" or "service" running on your node.

Why Protocols?

Using protocols allows your node to do many things at once:

• Handle chat messages (/chat/1.0)
• Respond to database queries (/db/1.0)
• Facilitate a VPN tunnel (/vpn/1.0)

All of these can run over the same physical connection between two peers.

Setting Up a Protocol Handler

Tell your node what to do when someone connects using a specific protocol:

const myProtocol = "/myapp/v1"

node.HandleProtocol(myProtocol, func(s *easyp2p.Stream) {
    defer s.Close()
    
    // Read from the stream
    buf := make([]byte, 1024)
    n, err := s.Read(buf)
    if err != nil {
        return
    }
    
    fmt.Printf("Received: %s\n", string(buf[:n]))
    
    // Respond back
    s.Write([]byte("Message received!"))
})

Connecting to a Peer

To talk to another node, you must know their Peer ID:

peerID, _ := peer.Decode("Qm...")
stream, err := node.ConnectTo(peerID, myProtocol)
if err != nil {
    // Handle error
}

// Write to the peer
stream.Write([]byte("Hello!"))

// Read response
result := make([]byte, 256)
n, _ := stream.Read(result)

PubSub (GossipSub) 🗣️

If you want to broadcast messages to everyone in a group (like a chat room), use Topics.

topic, _ := node.JoinTopic("general-chat")

// Receive broadcasts
topic.OnMessage(func(msg string, sender string) {
    fmt.Printf("[%s]: %s\n", sender, msg)
})

// Send broadcast
topic.Publish("Hello everyone!")

easyp2p uses GossipSub, which is a highly efficient peer-to-peer messaging protocol.