Principle:Elevenlabs Elevenlabs python Conversational Session
| Knowledge Sources | |
|---|---|
| Domains | Conversational_AI, WebSocket, Real_Time_Systems |
| Last Updated | 2026-02-15 00:00 GMT |
Overview
An event-driven session manager that orchestrates bidirectional real-time voice communication between a user and an AI agent over WebSocket, handling audio streaming, transcript callbacks, tool execution, and interruption management.
Description
Conversational Session is the core orchestration component of the ElevenLabs Conversational AI system. It manages the complete lifecycle of a voice conversation:
- Session establishment: Opens a WebSocket connection to the ConvAI endpoint with agent configuration
- Audio routing: Streams user microphone audio (via AudioInterface) to the server and plays agent audio responses
- Event handling: Processes server messages including agent responses, user transcripts, interruptions, pings, and tool calls
- Tool execution: Dispatches client tool calls to registered handlers and returns results
- Session termination: Gracefully shuts down audio, tools, and WebSocket connection
The session runs in a background thread with a non-blocking message receive loop (500ms timeout). It supports multiple callback types for observing conversation events (agent response, user transcript, latency, audio alignment, response corrections).
The system handles interruptions by tracking event IDs and discarding audio events that occurred before the interruption.
Usage
Use this principle when building a real-time voice AI agent. Create a Conversation instance with the SDK client, agent ID, audio interface, and desired callbacks, then call start_session() to begin. The session runs autonomously until end_session() is called.
Theoretical Basis
The Conversational Session follows an event-driven state machine pattern:
# Abstract conversation lifecycle
session = ConversationSession(agent_id, audio_io, tools, callbacks)
session.start() # Opens WS, starts audio, begins message loop
# Background loop (runs in thread):
while not stopped:
message = ws.recv(timeout=500ms)
match message.type:
case "audio" -> audio_io.output(decode(audio))
case "agent_response" -> callbacks.on_agent_response(text)
case "user_transcript"-> callbacks.on_user_transcript(text)
case "interruption" -> audio_io.interrupt(); update_interrupt_id
case "ping" -> ws.send(pong)
case "client_tool_call" -> tools.execute(name, params, ws.send)
session.end() # Stops audio, tools, WS