Protocols

NATS uses text-based protocols for all communication between clients, servers, and clusters. These protocols are designed to be simple, efficient, and easy to implement.

Protocol Types

Client Protocol

The fundamental protocol for client-server communication. This text-based protocol defines how clients connect, authenticate, publish messages, create subscriptions, and handle responses. Features include:

• Simple text-based commands (PUB, SUB, UNSUB)
• Optional TLS encryption
• Built-in heartbeat mechanism (PING/PONG)
• Support for request-reply patterns
• Header support for metadata

Route Protocol

Used for intra-cluster communication between NATS servers. Routes create a full mesh topology where every server connects to every other server in the cluster. Key characteristics:

• Automatic message routing between servers
• Interest propagation for efficient message delivery
• Cluster-wide state synchronization
• Fault tolerance and automatic failover

Leafnode Protocol

Enables lightweight, unidirectional connections from edge servers to a central cluster. Ideal for:

• IoT and edge deployments
• Hub-and-spoke architectures
• Reducing bandwidth usage
• Selective message propagation
• Account isolation

Gateway Protocol

Connects multiple NATS clusters into a super-cluster while maintaining cluster autonomy. Benefits include:

• Cross-cluster communication
• Geographic distribution
• Interest-only message exchange
• Account mapping and isolation
• Optimized for WAN connections

Protocol Selection

Use Case	Recommended Protocol
Client applications	Client Protocol
High availability cluster	Route Protocol
Edge/IoT deployments	Leafnode Protocol
Multi-region/Multi-cloud	Gateway Protocol

Common Protocol Features

All NATS protocols share these characteristics:

• Text-based - Human-readable for easy debugging
• Lightweight - Minimal overhead for high performance
• Secure - TLS support across all protocols
• Resilient - Automatic reconnection and failover
• Efficient - Interest-based message routing