ADK Orchestration

Guide for building multi-agent systems with delegation, orchestration, inter-agent communication, and real-time streaming capabilities. Enables specialized agents to collaborate on complex tasks with modern communication patterns.

When to Use

Multi-Agent Systems

• Routing requests to specialized sub-agents
• Building agent pipelines (sequential execution)
• Running agents concurrently (parallel execution)
• Creating hierarchical agent teams
• Cross-system agent communication (A2A)

Streaming & Real-Time

• Streaming text responses as they generate
• Real-time chat with user interrupts
• Voice agent interactions (Live API)
• Video processing and multimodal streaming
• WebSocket bidirectional communication

When NOT to Use

• Single agent with tools → Use @adk-agents and @adk-tools instead
• Callbacks and state → Use @adk-behavior instead
• Agent deployment → Use @adk-deployment instead

Key Concepts

Multi-Agent Patterns

Delegation routes requests to sub-agents based on their descriptions. The parent agent decides which child handles each request.

SequentialAgent executes sub-agents in order (A → B → C). Each agent receives the previous agent's output.

ParallelAgent runs sub-agents concurrently. Results are aggregated when all complete.

LoopAgent repeats execution until a condition is met. Useful for iterative refinement.

Hierarchy nests agent teams for complex organizations. Parent agents coordinate child teams.

A2A Protocol enables cross-system agent communication. Agents can call agents in other deployments.

Streaming Patterns

SSE (Server-Sent Events) streams text responses incrementally. Client receives partial responses as they generate.

Bidirectional Streaming enables real-time two-way communication. Users can interrupt agent responses mid-stream.

Live API powers voice and video agents. Use gemini-3-flash-live model for real-time audio/video processing.

Runner Types: Runner for basic execution, BidiStreamingRunner for bidirectional, LiveAPIRunner for voice/video.

References

Detailed guides with code examples:

Multi-Agent

• references/delegation.md - Sub-agent routing patterns
• references/orchestration.md - Sequential, Parallel, Loop agents
• references/advanced.md - Hierarchical and complex patterns
• references/a2a.md - Agent-to-Agent protocol

Streaming

• references/sse.md - Server-sent events streaming
• references/bidirectional.md - WebSocket bidirectional
• references/multimodal.md - Live API voice/video