RedPepper Documentation

Communucation Protocol

This document describes the protocol used for communication between the Manager and Agents.

Message Transport

The protocol uses a simple bidirectional message transport. This is intended to be somewhat generic and could be replaced with a different message transport if needed (e.g. WebSockets, message queues, etc.).

The default message transport is implemented using TLS-encrypted TCP sockets. Messages are passed back and forth as binary blobs prefixed with the message’s 32-bit encoded length.

Message Encoding

Messages are encoded as MessagePack dicts with a type field which determines both the semantics and the accepted message schema. See messages.py for the schema definitions.

Message Types

AgentHello and ManagerHello messages are used for initial connection setup.

Ping and Pong messages are used for connection keep-alive.

Request and Response messages are used for asynchronous request/response communication.

Notification messages are used for notifications which do not require a response.

Bye messages are used to close the connection gracefully.

Communication Flow

On startup (agent):

• Initiate connection to manager
• Send AgentHello
• Wait for ManagerHello with timeout
  • If timeout, close connection
• Validate ManagerHello details as needed
  • If validation fails, send Bye and close connection
• Start listening for incoming requests and notifications

On connection received (manager):

• Wait for AgentHello with timeout
  • If timeout, close connection
• Authenticate agent based on information in AgentHello
  • If authentication fails, send Bye and close connection
• Send ManagerHello
• Start listening for incoming messages and notifications

Periodically:

• Send Ping message
• Wait for Ping message with timeout
  • If timeout, close connection

Receive Request:

• Execute the request specified in the message
• Send Response with the request ID and the result of the request

Receive Response:

• Match the response to the request and return the result to the caller

Receive Notification:

• Handle the notification as needed without sending a response

Receive Bye:

• Close the connection

This site is open source. Improve this page.