What is A2a Langgraph

a2a-langgraph is an Agent-to-Agent (A2A) Protocol implementation built on top of LangGraph, designed to facilitate conversational interactions, including multi-turn dialogues and streaming responses.

Use cases

Use cases include building currency conversion agents, developing intelligent chatbots for customer service, and creating interactive applications that require multi-turn conversations.

How to use

To use a2a-langgraph, deploy it via Docker, set up your environment with the required API key, and run the agent using the provided commands. You can interact with the agent through a client that supports A2A protocol.

Key features

Key features include the ReAct pattern for reasoning, streaming support for real-time updates, checkpoint memory for maintaining conversation state, and a webhook-based push notification system for updates.

Where to use

a2a-langgraph can be used in various fields such as finance for currency conversion, customer support for conversational agents, and any application requiring interactive dialogue systems.

🤖 A2A Protocol 💬 from Enso Labs 🤖

This sample demonstrates a currency conversion agent built with LangGraph and exposed through the A2A protocol. It showcases conversational interactions with support for multi-turn dialogue and streaming responses. For more information checkout the OFFICIAL repo at https://github.com/google/A2A/tree/main

Docker Deploy

# Pull Image
docker pull ghcr.io/enso-labs/a2a-langgraph

# Run Image
docker run -p 10000:10000 --name a2a \
-e GOOGLE_API_KEY=$GOOGLE_API_KEY \
ghcr.io/enso-labs/a2a-langgraph

# Check Logs
docker logs -f a2a

Prerequisites

• Python 3.13 or higher
• UV
• Access to an LLM and API Key

Setup & Running

1. Navigate to the samples directory:

   cd samples/python/agents/langgraph
   

2. Create an environment file with your API key:

   echo "GOOGLE_API_KEY=your_api_key_here" > .env
   

3. Run the agent:

   # Basic run on default port 10000
   uv run .
   
   # On custom host/port
   uv run . --host 0.0.0.0 --port 8080
   

4. In a separate terminal, run an A2A client:

   uv run hosts/cli
   

Technical Implementation

• LangGraph ReAct Agent: Uses the ReAct pattern for reasoning and tool usage
• Streaming Support: Provides incremental updates during processing
• Checkpoint Memory: Maintains conversation state between turns
• Push Notification System: Webhook-based updates with JWK authentication
• A2A Protocol Integration: Full compliance with A2A specifications

Limitations

• Only supports text-based input/output (no multi-modal support)
• Uses Frankfurter API which has limited currency options
• Memory is session-based and not persisted between server restarts

Examples

Synchronous request

Request:

POST http://localhost:10000
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "id": 11,
  "method": "tasks/send",
  "params": {
    "id": "129",
    "sessionId": "8f01f3d172cd4396a0e535ae8aec6687",
    "acceptedOutputModes": [
      "text"
    ],
    "message": {
      "role": "user",
      "parts": [
        {
          "type": "text",
          "text": "How much is the exchange rate for 1 USD to INR?"
        }
      ]
    }
  }
}

Response:

{
  "jsonrpc": "2.0",
  "id": 11,
  "result": {
    "id": "129",
    "status": {
      "state": "completed",
      "timestamp": "2025-04-02T16:53:29.301828"
    },
    "artifacts": [
      {
        "parts": [
          {
            "type": "text",
            "text": "The exchange rate for 1 USD to INR is 85.49."
          }
        ],
        "index": 0
      }
    ],
    "history": []
  }
}

Multi-turn example

Request - Seq 1:

POST http://localhost:10000
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "id": 10,
  "method": "tasks/send",
  "params": {
    "id": "130",
    "sessionId": "a9bb617f2cd94bd585da0f88ce2ddba2",
    "acceptedOutputModes": [
      "text"
    ],
    "message": {
      "role": "user",
      "parts": [
        {
          "type": "text",
          "text": "How much is the exchange rate for 1 USD?"
        }
      ]
    }
  }
}

Response - Seq 2:

{
  "jsonrpc": "2.0",
  "id": 10,
  "result": {
    "id": "130",
    "status": {
      "state": "input-required",
      "message": {
        "role": "agent",
        "parts": [
          {
            "type": "text",
            "text": "Which currency do you want to convert to? Also, do you want the latest exchange rate or a specific date?"
          }
        ]
      },
      "timestamp": "2025-04-02T16:57:02.336787"
    },
    "history": []
  }
}

Request - Seq 3:

POST http://localhost:10000
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "id": 10,
  "method": "tasks/send",
  "params": {
    "id": "130",
    "sessionId": "a9bb617f2cd94bd585da0f88ce2ddba2",
    "acceptedOutputModes": [
      "text"
    ],
    "message": {
      "role": "user",
      "parts": [
        {
          "type": "text",
          "text": "CAD"
        }
      ]
    }
  }
}

Response - Seq 4:

{
  "jsonrpc": "2.0",
  "id": 10,
  "result": {
    "id": "130",
    "status": {
      "state": "completed",
      "timestamp": "2025-04-02T16:57:40.033328"
    },
    "artifacts": [
      {
        "parts": [
          {
            "type": "text",
            "text": "The current exchange rate is 1 USD = 1.4328 CAD."
          }
        ],
        "index": 0
      }
    ],
    "history": []
  }
}

Streaming example

Request:

{
  "jsonrpc": "2.0",
  "id": 12,
  "method": "tasks/sendSubscribe",
  "params": {
    "id": "131",
    "sessionId": "cebd704d0ddd4e8aa646aeb123d60614",
    "acceptedOutputModes": [
      "text"
    ],
    "message": {
      "role": "user",
      "parts": [
        {
          "type": "text",
          "text": "How much is 100 USD in GBP?"
        }
      ]
    }
  }
}

Response:

data: {"jsonrpc":"2.0","id":12,"result":{"id":"131","status":{"state":"working","message":{"role":"agent","parts":[{"type":"text","text":"Looking up the exchange rates..."}]},"timestamp":"2025-04-02T16:59:34.578939"},"final":false}}

data: {"jsonrpc":"2.0","id":12,"result":{"id":"131","status":{"state":"working","message":{"role":"agent","parts":[{"type":"text","text":"Processing the exchange rates.."}]},"timestamp":"2025-04-02T16:59:34.737052"},"final":false}}

data: {"jsonrpc":"2.0","id":12,"result":{"id":"131","artifact":{"parts":[{"type":"text","text":"Based on the current exchange rate, 1 USD is equivalent to 0.77252 GBP. Therefore, 100 USD would be approximately 77.252 GBP."}],"index":0,"append":false}}}

data: {"jsonrpc":"2.0","id":12,"result":{"id":"131","status":{"state":"completed","timestamp":"2025-04-02T16:59:35.331844"},"final":true}}

Learn More

• A2A Protocol Documentation
• LangGraph Documentation
• Frankfurter API
• Google Gemini API