AG-UI + A2A Multi-Agent Communication Demo

A demonstration of Agent-to-Agent (A2A) communication between different AI agent frameworks using the AG-UI Protocol and A2A Middleware.

Quick Start

Prerequisites

• Node.js 18+
• Python 3.10+
• Google API Key
• OpenAI API Key

Setup

1. Install frontend dependencies:

npm install

2. Install Python dependencies:

cd agents
python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
pip install -r requirements.txt

3. Configure environment variables:

cp .env.example .env
# Edit .env and add your GOOGLE_API_KEY and OPENAI_API_KEY

4. Start all services:

npm run dev

This starts:

• UI on http://localhost:3000
• Orchestrator on http://localhost:9000
• Itinerary Agent on http://localhost:9001
• Budget Agent on http://localhost:9002
• Restaurant Agent on http://localhost:9003
• Weather Agent on http://localhost:9005

Usage

Try asking: "Plan a 3-day trip to Tokyo" or "I want to visit New York for 5 days"

The orchestrator will coordinate the agents to:

1. Collect trip requirements (destination, days, people, budget level)
2. Generate an itinerary
3. Provide weather forecast
4. Recommend restaurants for each day
5. Estimate budget and request approval

Agent interactions are visible in the UI with message flow visualization.

What This Demonstrates

This demo shows how specialized agents built with different frameworks can communicate via the A2A protocol:

LangGraph Agents (Python + OpenAI)

• Itinerary Agent (Port 9001) - Creates day-by-day travel itineraries
• Restaurant Agent (Port 9003) - Recommends meal plans

ADK Agents (Python + Gemini)

• Budget Agent (Port 9002) - Estimates travel costs
• Weather Agent (Port 9005) - Provides weather forecasts

Orchestrator

• Orchestrator Agent (Port 9000) - Coordinates all agents via A2A middleware

The demo includes multi-framework integration, structured JSON outputs, generative UI components, human-in-the-loop workflows, and real-time message visualization

Architecture

┌──────────────────────────────────────────┐
│ Next.js UI (CopilotKit)                  │
└────────────┬─────────────────────────────┘
             │ AG-UI Protocol
┌────────────┴─────────────────────────────┐
│ A2A Middleware                            │
│ - Routes messages between agents          │
└──────┬───────────────────────────────────┘
       │ A2A Protocol
       │
       ├─────► LangGraph Agents (OpenAI)
       │       ├── Itinerary (9001)
       │       └── Restaurant (9003)
       │
       └─────► ADK Agents (Gemini)
               ├── Budget (9002)
               └── Weather (9005)
       ▲
       │
┌──────┴──────────┐
│ Orchestrator    │
│ (Port 9000)     │
└─────────────────┘

Project Structure

ag-ui-a2a-demo/
├── app/
│   ├── api/copilotkit/route.ts       # A2A middleware setup
│   └── page.tsx                      # Main UI
│
├── components/
│   ├── a2a/                          # A2A message components
│   ├── travel-chat.tsx               # Chat orchestration
│   └── [other UI components]
│
├── agents/                           # Python agents
│   ├── orchestrator.py               # Orchestrator (9000)
│   ├── itinerary_agent.py            # LangGraph (9001)
│   ├── budget_agent.py               # ADK (9002)
│   ├── restaurant_agent.py           # LangGraph (9003)
│   └── weather_agent.py              # ADK (9005)
│
└── .env.example

Technologies

• Frontend: Next.js, CopilotKit, AG-UI Client, Tailwind CSS
• Backend: Google ADK (Gemini), LangGraph (OpenAI), FastAPI
• Protocols: A2A (agent-to-agent), AG-UI (agent-UI)
• Middleware: @ag-ui/a2a-middleware

Troubleshooting

Agents not connecting? Verify all services are running by checking http://localhost:9000-9005

Missing API keys? Ensure .env contains GOOGLE_API_KEY and OPENAI_API_KEY

Python issues? Activate the virtual environment: cd agents && source .venv/bin/activate

Learn More

• AG-UI Protocol
• A2A Protocol
• Google ADK
• LangGraph
• CopilotKit

License

MIT