A2A Server Plugin

Author: nacos
Version: 0.0.1
Type: extension
Repository: https://github.com/nacos-group/nacos-dify-plugins

Expose Dify apps as A2A (Agent-to-Agent) protocol agents for external discovery and invocation.

Features

A2A Protocol Support: Expose any Dify App (Chatbot/Agent/Chatflow/Workflow) as an A2A-compatible agent
Agent Discovery: Support endpoint for agent metadata discovery
Nacos Integration: Optional registration to Nacos Agent Registry for centralized agent management
Multi-turn Conversation: Maintain conversation context across multiple requests using Dify Plugin Storage
Streaming Response: Support streaming mode for Agent Chat Apps

Quick Start

Step 1: Install the Plugin

Download the plugin package from GitHub Releases
In Dify, go to Plugins → Install Plugin
Upload the plugin package and complete the installation

Step 2: Create an Endpoint (First Time)

Go to Plugins → a2a_server → Create Endpoint
Configure the required settings:

Parameter	Example Value	Description
Dify App	Select your app	The Dify App to expose
Agent Name		Display name for your agent
Agent Description		What your agent does
Agent Public URL		Placeholder value (will update later)

Click Save to create the endpoint

Important: The endpoint ID is generated by Dify after you save. You cannot know the correct URL before creating the endpoint. Use a placeholder value first (e.g., ).

Step 3: Update the Correct URL

After saving, Dify will generate an endpoint ID (e.g., ). Now you need to update the URL:

Go back to Edit Endpoint
Update Agent Public URL to the correct value:
Click Save again

Your final A2A URLs will be:

Step 4: Test the Agent

Test by fetching the Agent Card:

If successful, you'll receive a JSON response with your agent's metadata.

Note: If Nacos registration is enabled, the agent will be registered to Nacos when you call this GET endpoint for the first time. Before calling this endpoint, the agent is NOT registered to Nacos.

For sending messages via the POST endpoint, it's recommended to use an A2A SDK or A2A-compatible client.

Configuration Reference

Parameter	Required	Default	Description
Dify App	Yes	-	Select the Dify App to expose as A2A agent
Agent Name	Yes	-	Name of the A2A agent
Agent Description	Yes	-	Description of the agent's capabilities
Agent Public URL	Yes	-	Public URL where this agent can be accessed
Agent Version	No		Version string
Enable Nacos Registry	Yes		Enable/disable Nacos registration
Nacos Address	No	-	Nacos server address (e.g., )
Nacos Namespace ID	No		Nacos namespace ID
Nacos Username	No	-	Username for Nacos authentication
Nacos Password	No	-	Password for Nacos authentication
Aliyun AccessKey	No	-	AccessKey for Aliyun MSE Nacos
Aliyun SecretKey	No	-	SecretKey for Aliyun MSE Nacos

Nacos Registration

When to Use Nacos

You have multiple A2A agents and want centralized discovery
You're using Nacos as your service registry
You want agents to discover each other automatically

Registration Behavior

Lazy Registration: The agent is NOT registered to Nacos immediately when the plugin starts
First Request Trigger: Registration only occurs when the first GET request is made to
Cache-based Deduplication: After registration, the AgentCard is cached locally (15 seconds TTL) to avoid duplicate registrations
Change Detection: If the agent configuration changes (name, description, or URL), the agent will be re-registered to Nacos
Remote Sync: After successful registration, the plugin fetches the AgentCard from Nacos to ensure cache consistency

Configuration Examples

Self-hosted Nacos:

Aliyun MSE Nacos:

API Reference

Endpoints

Method	Path	Description
GET		Returns AgentCard metadata
POST		JSON-RPC endpoint for A2A protocol

Supported JSON-RPC Methods

Method	Description
	Send a message to the agent and receive a response

Response Format

Troubleshooting

Agent Card Not Returned

Check that the endpoint is correctly configured
Verify the URL path includes
Check Dify logs for error messages

Nacos Registration Failed

Verify Nacos server is accessible from Dify
Check authentication credentials
Ensure the namespace ID exists in Nacos

Message Send Returns Error

Verify the Dify App is properly configured
Check that the app supports chat/conversation mode
Review the JSON-RPC request format

Requirements

Dify version with plugin support
Python 3.12+
(Optional) Nacos server for agent registration

License

Apache License 2.0

a2a_server