Dify Officially Launched the Nacos A2A Plugin, Completing Its Bidirectional Multi-agent Collaboration Capabilities

This article introduces Dify's Nacos A2A plugins, enabling bidirectional agent collaboration—discovering external A2A agents and exposing Dify apps as discoverable agents via Nacos Registry.

By Zhuo Guang

I. Background and Challenges: Typical Issues in Multi-Agent Collaboration

With the rapid development of AI Agent technology, a single agent has become insufficient to meet the demands of complex business scenarios. Multi-Agent Collaboration is becoming a mainstream trend in AI applications—allowing multiple agents with different expertise to work together to complete complex tasks.

The A2A (Agent-to-Agent) protocol, released by Google in early 2025, provides an important foundation for standardized communication between multi-agents. The A2A protocol defines standards for discovery, capability description, and task interaction between agents, enabling seamless collaboration among agents from different sources and frameworks.

However, the Dify platform currently does not natively support the A2A protocol. This means that developers cannot directly discover and invoke agents that follow the A2A standard within Dify, lacking effective means to integrate with the A2A ecosystem. Specifically, Dify developers face the following challenges:

● Protocol Incompatibility: Dify does not natively support the A2A protocol, cannot directly parse AgentCards, handle A2A message formats, and is completely isolated from the existing A2A Agent ecosystem.

● Difficulty in Agent Discovery: Multiple A2A Agents are deployed in different environments, with no standard way for Dify applications to discover and manage these agents, requiring extensive custom development for each integration.

● Limited Dynamic Selection: In traditional methods, Dify applications can only call a single agent that is hard-coded in advance, unable to dynamically choose the most suitable agent based on actual task requirements.

● Complex Collaboration Orchestration: When business requires multiple agents to collaborate, developers need to conduct extensive conditional judgments and routing logic within workflows, leading to high development and maintenance costs.

● Lack of Unified Registration Center: Without a centralized platform to manage A2A Agents, it is difficult to conduct unified registration, discovery, and governance of agents.

● Inability to Expose Externally: The agent applications built on Dify can only be used within the Dify platform and cannot provide services externally using standard protocols, making it hard for other agents within the A2A ecosystem to discover and invoke them.

These issues result in Dify developers facing the dilemma of protocol incompatibility, high integration costs, poor scalability, low flexibility, and inability to interconnect externally when building multi-agent applications.

II. Solutions: Nacos Agent Registry + A2A Plugin Combination

To address the above issues, the Nacos team has developed a bidirectional A2A protocol integration solution for the Dify platform, filling the gap in A2A protocol support with two complementary plugins, allowing Dify applications to both invoke external A2A agents and be called as A2A agents by external systems.

Nacos 3.0 has expanded its support for A2A Agents on the basis of the MCP Registry, launching the Nacos Agent Registry—a unified AI agent registration and discovery platform. Combined with the A2A plugin combination, Dify developers can:

A2A Discovery Plugin (Invoke External Agents):

● Open Up A2A Protocol: The plugin contains complete A2A protocol support, automatically parsing AgentCards and handling standard message formats, allowing Dify to seamlessly connect with the A2A ecosystem.

● Unified Agent Discovery: Automatically discover all registered A2A Agents from the Nacos Agent Registry without manually configuring the connection information for each agent.

● Dynamic Agent Selection: LLM can intelligently select the most suitable agent for invocation based on task requirements from multiple available agents.

● Flexible Discovery Modes: Supports both Nacos mode and URL mode for discovery, satisfying needs for different deployment scenarios.

A2A Server Plugin (Expose Dify Applications):

● Standard Protocol Exposure: Expose any application (Chatbot/Agent/Chatflow/Workflow) within Dify as an agent compliant with A2A protocol standards.

● Automatic Registration and Discovery: Supports automatically registering Dify applications to the Nacos Agent Registry, allowing other agents to discover and invoke them.

● Support for Multi-Turn Conversations: Maintains session context based on Dify Plugin Storage, supporting continuous conversations across requests.

● Standard Endpoint: Provides a standard /.well-known/agent.json endpoint for agent metadata discovery.

Currently, the official Nacos A2A plugins have been officially launched in the Dify official plugin marketplace:

● A2A Discovery Plugin (A2A Agent Client)

● A2A Server Plugin

Overall Architecture

III. Detailed Overview of Core Features

3.1 A2A Discovery Plugin: Invoke External Agents

3.1.1 Two Modes of Agent Discovery

Nacos Mode (Recommended)

Manage and discover agents uniformly through the Nacos Agent Registry. Simply register A2A Agents in Nacos, and Dify applications can automatically discover and invoke them.

Advantages:

● Centralized management, unified maintenance of agent information

● Supports dynamic registration and deregistration without restarting Dify applications

● Seamless integration with the Nacos ecosystem, enjoying enterprise-level governance capabilities

Configuration Example:

discovery_type: nacos
available_agent_names: translator_agent,search_agent,code_agent
namespace_id: public

URL Mode

Discover directly through the standard URL of A2A Agents, suitable for lightweight scenarios that don't require Nacos.

Configuration Example:

discovery_type: url
available_agent_urls: {
  "translator_agent": "http://host1:8080/.well-known/agent.json",
  "search_agent": "http://host2:8080/.well-known/agent.json"
}

3.1.2 Two Core Tools

Get Agent Information (get_a2a_agent_information)

Query detailed information about all configured A2A Agents, including:

● Agent Name (agent_name)

● Function Description (description)

● Skill List (skills)

LLM uses this information to understand each agent's capabilities, providing a basis for subsequent intelligent selection.

Invoke Agent (call_a2a_agent)

According to LLM's selection, sends query messages to the designated A2A Agent and receives responses. Supports:

● Dynamically selecting target agents

● Customizing query messages

● Complete context passing

3.1.3 Dynamic Agent Selection Workflow

Through the cooperation of the above two tools, Agents within Dify can achieve:

A comprehensive understanding of available agent resources
Intelligently match the best agent based on specific tasks
Realize true dynamic collaboration among multiple agents

3.2 A2A Server Plugin: Expose Dify Applications

The A2A Server plugin enables Dify applications to provide services externally using the standard A2A protocol, allowing other agents to discover and invoke them.

3.2.1 Supported Application Types

A2A Server supports exposing the following types of Dify applications as A2A agents:

Application Type	Description
Chatbot	Conversational applications that support multi-turn conversations
Agent	Agent applications with tool invocation capabilities
Chatflow	Applications based on conversational processes
Workflow	Workflow applications

3.2.2 Two Core Endpoints

Agent Metadata Endpoint (GET /.well-known/agent.json)

Returns an AgentCard that complies with the A2A protocol, containing:

● Agent Name (name)

● Function Description (description)

● Access Address (url)

● Version Information (version)

● Capability Declarations (capabilities)

● Skill List (skills)

External callers discover the agent's capabilities and invocation methods through this endpoint.

JSON-RPC Invocation Endpoint (POST /a2a)

Handles JSON-RPC requests adhering to the A2A protocol standards. Supports:

● message/send method: sends a message to the agent and receives a response

● Managing multi-turn conversation contexts

● Complete task state management

3.2.3 Automatic Registration with Nacos

Once Nacos registration is enabled, the A2A Server will automatically register the Dify application to the Nacos Agent Registry upon receiving the first AgentCard request. After registration, other A2A agents can discover and invoke this Dify application through Nacos.

3.2.4 Support for Multi-Turn Conversations

The A2A Server implements cross-request session context management based on Dify Plugin Storage:

● Automatically maintain conversation_id mappings

● Support continuous multi-turn dialogues

● Persist session state storage

IV. Practical Tutorial: Build Multi-Agent Collaborative Applications

This chapter will demonstrate the usage of the A2A Discovery and A2A Server plugins through two specific cases.

4.1 Using A2A Discovery to Invoke External Agents

Let's use a specific example to demonstrate how to build a multi-agent collaborative AI assistant using the A2A Discovery plugin.

Scenario Description

Assume we need to build an intelligent customer service system that requires invoking the following three specialized agents:

Translation Agent: Handles multilingual translation needs
Search Agent: Queries product information and knowledge bases
Customer Service Agent: Handles order inquiries and after-sale issues

Step One: Register A2A Agent in Nacos

There are two ways to register A2A Agents in the Nacos Agent Registry:

Method One: Manual Registration via Console

Log into the MSE Nacos console
Go to "Agent Registration Center"
Add information for each A2A Agent (name, access address, description, etc.)

Method Two: AgentScope Automatic Registration (Recommended)

AgentScope is an open-source framework developed by Alibaba, focusing on multi-agent development with developers at its core. Its main goal is to address challenges in the construction, operation, and management of agents, providing a complete production-grade solution covering the entire lifecycle of "development, deployment, monitoring".

The latest version of AgentScope fully supports the A2A protocol and integrates Nacos as the default implementation for A2A Registry, establishing a complete distributed multi-agent collaborative system from development to deployment. A2A Agents built using AgentScope can automatically register with Nacos without manual configuration. Below is reference code:

from agentscope_runtime.engine.app import AgentApp
from agentscope_runtime.engine.deployers.adapter.a2a import (
    AgentCardWithRuntimeConfig,
)
from agentscope_runtime.engine.deployers.adapter.a2a.nacos_a2a_registry import (
    NacosRegistry,
)
from v2.nacos import ClientConfigBuilder

# Create Nacos Registry instance
registry = NacosRegistry(
    nacos_client_config=ClientConfigBuilder()
    .server_address("mse-xxx.nacos.mse.aliyuncs.com:8848")
    # Other optional configuration items
    .build()
)

# Create an AgentApp
app = AgentApp(
    app_name="translator_agent",
    app_description="TestAgent",
    # Configure the registry within a2a_config
    a2a_config=AgentCardWithRuntimeConfig(registry=registry),
)

For more integration methods, please refer to the AgentScope Official Documentation.

Step Two: Install and Configure A2A Discovery Plugin

Search for “A2A Agent Client” in the Dify plugin marketplace or directly visit the plugin page
Click to install the plugin
Configure Nacos connection information:

Parameter	Description
Nacos Agent Registration Center Address	e.g.: `mse-xxx.nacos.mse.aliyuncs.com:8848`
Nacos Username	Nacos authentication username (optional)
Nacos Password	Nacos authentication password (optional)
Alibaba Cloud AccessKey	For MSE Nacos (optional)
Alibaba Cloud SecretKey	For MSE Nacos (optional)

Step Three: Create Dify Agent Application

1. Create a new Agent application in Dify

2. Add the two tools from the A2A Discovery plugin:

● get_a2a_agent_information

● call_a2a_agent

3. Configure tool parameters:

discovery_type: nacos
available_agent_names: translator_agent,search_agent,customer_service_agent
namespace_id: public

4. Set system prompt:

"You are an intelligent customer service assistant capable of invoking multiple specialized agents to handle user requests.

Workflow:

First, invoke get_a2a_agent_information to retrieve information about all available agents.
Based on the type of the user's query, select the most suitable agent.
Invoke call_a2a_agent to send the request to the selected agent.
Integrate the response results to provide a comprehensive answer to the user.
Available specialized agents include translation, search, customer service, etc. Please make intelligent selections based on the specific characteristics of the task."

Step Four: Test Validation

After deploying the application, try the following dialogues:

User: Please help me translate "How to return the product?" into Chinese

AI Assistant (Internal Process):

Call get_a2a_agent_information to get the list of agents
Identify this as a translation task and select translator_agent
Call call_a2a_agent to send the translation request
Return the translation result

User: I want to query the logistics status of order #12345

AI Assistant (Internal Process):

Identify this as a customer service issue and select customer_service_agent
Invoke the agent to get order information
Return the logistics status

4.2 Using A2A Server to Expose Dify Applications

Now let's demonstrate how to use the A2A Server plugin to expose Dify applications as A2A agents, enabling other systems to discover and invoke them.

Scenario Description

Assuming we have already built a powerful "Intelligent Customer Service Assistant" application in Dify, we now wish to expose it as an A2A agent, allowing:

● Other AgentScope applications to call it

● Other agents in the A2A ecosystem to discover and collaborate with it

● External AI applications to access it through standard protocols

Step One: Install A2A Server Plugin

Search for “A2A Server” in the Dify plugin marketplace or directly visit the plugin page
Click to install the plugin

Step Two: Create Endpoint

1. Enter the plugin management page and find the A2A Server plugin

2. Click "Create Endpoint"

3. Configure basic parameters:

Parameter	Description	Example Value
Dify App	Select the application to be exposed	Intelligent Customer Service Assistant
Agent Name	Agent Name	smart-service-agent
Agent Description	Agent Description	Intelligent customer service assistant, supports order inquiries, after-sale services, product consultations
Agent Public URL	Public access address (fill in a placeholder first)	`https://your-domain.com/a2a`
Agent Version	Version Number	1.0.0

4. Click save, and Dify will generate an Endpoint ID

Step Three: Update the Correct URL

After saving, obtain the generated Endpoint ID (e.g., abc123), then:

1. Return to edit the Endpoint

2. Update the Agent Public URL to the correct address:

https://your-domain.com/e/abc123/a2a

3. Save the configuration

The final A2A endpoint:

● AgentCard Address: https://your-domain.com/e/{endpoint_id}/a2a/.well-known/agent.json

● JSON-RPC Address: https://your-domain.com/e/{endpoint_id}/a2a

Step Four: Configure Nacos Registration (Optional)

If you wish for agents to be automatically discovered, you can configure Nacos registration:

Parameter	Description
Enable Nacos Registration	On
Nacos Address	e.g.: `mse-xxx.nacos.mse.aliyuncs.com:8848`
Namespace ID	Default `public`
Username/Password	Nacos authentication information (optional)
AccessKey/SecretKey	Specific to Alibaba Cloud MSE Nacos (optional)

Step Five: Test Validation

Test AgentCard Retrieval

curl https://your-domain.com/e/{endpoint_id}/a2a/.well-known/agent.json

Successful return example:

{
  "name": "smart-service-agent",
  "description": "Smart customer service assistant, supports order inquiry, after-sales service, and product consultation.",
  "url": "https://your-domain.com/e/abc123/a2a",
  "version": "1.0.0",
  "capabilities": {
    "streaming": false,
    "push_notifications": false
  },
  "skills": [
    {
      "id": "dify_app",
      "name": "smart-service-agent",
      "description": "Smart customer service assistant, supports order inquiry, after-sales service, and product consultation."
    }
  ]
}

Test Message Sending

Use A2A SDK or compatible clients to send messages:

from a2a.client import A2AClient

client = A2AClient("https://your-domain.com/e/{endpoint_id}/a2a")
response = client.send_message("I'd like to check the status of order #12345")
print(response.text)

Integration with AgentScope

After configuring AgentScope, AgentScope applications can automatically discover and invoke this Dify agent through Nacos:

from agentscope.agent import A2AAgent
from agentscope.a2a import NacosAgentCardResolver
from agentscope.message import Msg
from nacos.client import ClientConfig # [Note] The original code is missing the import for this line; you need to add it if using ClientConfig.

# Python AgentScope v1.0.11 or above
# Create Nacos AgentCard Resolver
nacos_resolver = NacosAgentCardResolver(
    remote_agent_name="my-remote-agent",  # The name of the agent registered in Nacos
    nacos_client_config=ClientConfig(
        server_addresses="http://localhost:8848",  # Nacos server address
        # Other optional configurations
    ),
)
# Use the Resolver to create an A2AAgent, discovering the Agent by name from Nacos
agent = A2AAgent(
    agent_card=await nacos_resolver.get_agent_card()
)

For more integration methods, please refer to the AgentScope Official Documentation.

V. Nacos Agent Registry Enterprise Capabilities

Unified Registration and Discovery

All A2A Agents are centrally registered in Nacos, and developers do not need to worry about the specific deployment locations of agents. When adding new agents, registration in Nacos is all that is required, and Dify applications can automatically discover and invoke them, supporting dynamic online and offline capabilities.

Multi-Tenant Isolation

Based on Nacos' namespace isolation mechanism, agents in different environments (development, testing, production) or different business lines can be completely isolated without affecting each other, meeting enterprise-level multi-tenant scenarios.

Health Checks

Nacos automatically monitors the operating status of each agent. When an Agent is unavailable, it is automatically removed from the service list to avoid invocation failures; when recovered, it automatically comes back online.

Metadata Management

Supports dynamically updating agents' descriptions, skill lists, and other metadata at runtime without requiring service restarts. This is very friendly for agent capability iteration and upgrades.

Access Control

Through Nacos' authentication and authorization mechanism, precise control can be exercised over which applications can access which agents, ensuring the security of enterprise-level applications.

Ecological Integration

Nacos Agent Registry not only supports A2A protocols but also seamlessly interfaces with Alibaba Cloud AI Gateway, AgentScope, and other components to build a comprehensive agent governance ecosystem.

Capability	Description
Unified Registration and Discovery	All A2A Agents are centrally registered, supporting automatic discovery and dynamic updates
Multi-Tenant Isolation	Environment isolation of agents based on Namespace
Health Checks	Automatically detect agent availability, with automatic removal on failure
Metadata Management	Update agent descriptions, skills, and other information at runtime without restarting
Access Control	Access to Nacos supports authentication and authorization, ensuring agent invocation security
Ecological Integration	Seamless integration with frameworks like AgentScope

VI. Summary and Outlook

The A2A plugin combination fills the gap in A2A protocol support on the Dify platform, providing Dify developers with bidirectional multi-agent collaboration capabilities:

● Bidirectional Protocol Support: A2A Discovery invokes external agents, A2A Server exposes Dify applications, achieving complete communication within the A2A ecosystem

● Simplified Integration: Through Nacos Agent Registry, a single configuration allows the discovery of all agents and enables Dify applications to be auto-discovered

● Intelligent Selection: LLM dynamically selects the most suitable agent based on task requirements

● Standard Protocols: Fully compliant with the Google A2A protocol, seamlessly compatible with various implementations

● Ecological Interconnectivity: Deep integration with mainstream agent frameworks like AgentScope, allowing Dify applications to be discovered and invoked by other AI platforms

● Enterprise-Level Governance: Relying on the Nacos platform, enjoy complete agent management capabilities

As the AI multi-agent technology continues to evolve, Nacos will continue to deepen its efforts in the AI Agent ecosystem, from MCP Server management to A2A Agent collaboration, deeply integrating with mainstream agent frameworks like AgentScope to provide developers with a more complete agent governance platform. Through the combination of the A2A Discovery and A2A Server plugins, Dify developers can now build truly open and interconnected agent applications—capable of invoking various specialized agents in the ecosystem while also exposing their own agent capabilities to the entire A2A ecosystem. In the future, we will support more agent protocols and richer governance capabilities to assist developers in building more powerful AI applications.