messages

Handshake protocol message types

This module defines the message types used during the handshake protocol between nodes in a distributed system. These messages facilitate capability negotiation and connection establishment.

Protocol Flow

Initiator sends Hello with node info and capabilities
Responder replies with Capabilities or Reject
If compatible, Responder sends Accept with agreed protocol/version
Connection is established

Example

let hello = Hello(
  node_info: "node@host:9000",
  capabilities: my_capabilities,
)

Types

Accept

</>

Connection acceptance message.

Sent when the handshake is successful and both nodes agree on a protocol and version to use for communication.

pub type Accept {
  Accept(protocol: String, version: Int)
}

Constructors

```
Accept(protocol: String, version: Int)
```

Capabilities

</>

Capability advertisement message.

Sent by the responder to share its own capabilities after receiving a Hello message. Used during capability negotiation to find a common protocol version and features.

pub type Capabilities {
  Capabilities(capabilities: List(capability.Capability))
}

Constructors

Capabilities(capabilities: List(capability.Capability))

Hello

</>

Initial handshake message sent by the initiator.

Contains the node’s identity information and its advertised capabilities. The responder uses this to determine compatibility and decide whether to accept or reject the connection.

pub type Hello {
  Hello(
    node_info: String,
    capabilities: List(capability.Capability),
  )
}

Constructors

Hello(
  node_info: String,
  capabilities: List(capability.Capability),
)

Reject

</>

Connection rejection message.

Sent when the handshake fails, typically due to incompatible capabilities or other errors. Includes a human-readable reason.

pub type Reject {
  Reject(reason: String)
}

Constructors

```
Reject(reason: String)
```