mqtt0 (Rust)

Crate Layout

• lib.rs: public exports, crate overview
• client.rs: async QoS 0 client
• broker.rs: async broker with ACL hooks
• protocol.rs: MQTT encode/decode
• transport.rs: TCP/TLS/WebSocket transport abstraction
• trie.rs: subscription routing
• types.rs: public types and traits

Public Interfaces

• Client, ClientConfig: async connect/subscribe/publish/recv
• Broker, BrokerConfig, BrokerBuilder: broker setup and lifecycle
• Authenticator, Handler: ACL and message handling
• Message, ProtocolVersion, QoS
• TransportType, Transport (feature-gated TLS/WebSocket)

Design Notes

• Fully async, based on Tokio and mpsc channels.
• Builder pattern for broker configuration and hooks.
• Transport features are behind Cargo feature flags (TLS, WebSocket).

Differences vs Go

• Rust uses async traits for client/broker operations.
• TLS/WebSocket support is feature-gated.
• Broker construction encourages builder configuration.