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Transports (Message Passing)

Transports deliver A2UI messages from agents to clients. A2UI is transport-agnostic—use any method that can send JSON.

The actual component rendering is done by the renderer, and the agents are responsible for generating the A2UI messages. Getting the messages from the agent to the client is the job of the transport.

How It Works

Agent → Transport → Client Renderer

A2UI defines a sequence of JSON messages. The transport layer is responsible for delivering this sequence from the agent to the client. A common transport mechanism is a stream using a format like JSON Lines (JSONL), where each line is a single A2UI message.

Available Transports

Transport Status Use Case
A2A Protocol ✅ Stable Multi-agent systems, enterprise meshes
AG UI ✅ Stable Full-stack React applications
REST API 📋 Planned Simple HTTP endpoints
WebSockets 💡 Proposed Real-time bidirectional
SSE (Server-Sent Events) 💡 Proposed Web streaming

A2A Protocol

The Agent2Agent (A2A) protocol provides secure, standardized agent communication. An A2A extension provides easy integration with A2UI.

Benefits:

  • Security and authentication built-in.
  • Bindings for many message formats, auth, and transport protocols.
  • Clean separation of concerns.

If you are using A2A, this should be nearly automatic.

TODO: Add a detailed guide.

See: A2A Extension Specification

AG UI

AG UI translates A2UI messages to AG UI events and handles transport and state sync automatically. It is the recommended transport for React / Next.js clients.

See: Use A2UI with Any Agent Framework (Using AG-UI) — guide to setting up CopilotKit with your agent framework of choice and enabling A2UI rendering.

Custom Transports

You can use any transport that sends JSON:

HTTP/REST:

// TODO: Add an example

WebSockets:

// TODO: Add an example

Server-Sent Events:

// TODO: Add an example

Next Steps