A2A Protocol Technical Documentation

What is the A2A Protocol?

The A2A (Agent-to-Agent) Protocol is an open-source agent communication protocol initiated by Google and supported by over 50 top technology partners. This protocol aims to become the HTTP of the agent internet era, building an open, secure, and efficient collaboration network for billions of agents.

Core Features

• Open Standard: Uses the Apache 2.0 license, providing complete technical specifications.
• High Interoperability: Supports mainstream frameworks like LangGraph, CrewAI, AutoGen, etc.
• Enterprise-Grade Features: Built-in security authentication, monitoring management, and performance optimization.
• Active Community: Continuously updated SDKs, rich tool support, and case studies.

Design Principles

1. Embrace Agent Capabilities

   • Allows agents to collaborate in natural, unstructured patterns.
   • No need for shared memory, tools, or context.
   • Enables true multi-agent scenarios.

2. Build on Existing Standards

   • Adopts widely accepted technical standards like HTTP, SSE, and JSON-RPC.
   • Facilitates integration with existing enterprise IT systems.

3. Secure by Default

   • Supports enterprise-grade authentication and authorization.
   • Ensures only authorized users and systems can access agents.

4. Support Long-Running Tasks

   • Flexibly supports various scenarios from quick tasks to complex research.
   • Provides real-time feedback, notifications, and status updates.

5. Modality Agnostic

   • Supports various interaction forms like text, audio, and video streams.
   • Supports rich UI interactions like forms and iframes.

Participant Roles

The A2A protocol defines three main participants:

1. User: The entity (human or service) using the agent system to complete tasks.
2. Client: The entity representing the user that sends requests to the agent.
3. Server: The agent providing the service, i.e., the A2A server.

Documentation Navigation

Introduction

• Background of A2A Protocol
• Design Goals and Principles
• Technical Architecture Overview

Core Concepts

• Detailed Explanation of AgentCard
• Task Management Mechanism
• Communication Mechanism
• Security Mechanism

Getting Started

• Environment Setup and Preparation
• Running Your First Agent
• Basic Development Guide

Code Examples

• Complete JavaScript Example
• Complete Python Example
• Framework Integration Examples

Demo Applications

• Web Application Example
  • Application Architecture Overview
  • Component Usage Instructions
• Command-Line Tool Example
  • CLI Tool Introduction
  • Usage Instructions

FAQ

• Development Troubleshooting
• Best Practice Recommendations
• Troubleshooting Guide

🚀 Getting Started

1. Quick Start

   • Environment Setup
   • Installation & Configuration
   • First Application

2. Core Concepts

   • Agent Model
   • Protocol Structure
   • Message Format

💡 Development Guide

Basic Features

1. Agent Management

   • Lifecycle Management
   • Capability Description
   • State Synchronization

2. Message Communication

   • Sync/Async Modes
   • Message Format
   • Error Handling

3. Security Mechanisms

   • Authentication
   • Access Control
   • Encrypted Transport

Advanced Features

1. Capability Discovery

   • Service Registration
   • Capability Query
   • Dynamic Discovery

2. Event System

   • Event Types
   • Subscription Mechanism
   • Processing Flow

📚 Framework Integration

Major Frameworks

1. LangGraph

   • Quick Integration
   • Best Practices
   • Code Examples

2. CrewAI

   • Configuration Guide
   • Feature Examples
   • Common Issues

3. AutoGen

   • Integration Solutions
   • API Usage
   • Performance Optimization

🔧 Operations & Deployment

Deployment Solutions

1. Local Deployment
2. Container Deployment
3. Cloud Native Deployment

Operations Guide

1. Monitoring & Alerts
2. Log Management
3. Performance Optimization

📖 API Reference

Interface Documentation

• Core API
• Extension API
• Event API

SDK Documentation

• Python SDK
• JavaScript SDK
• Java SDK

🎯 Best Practices

Architecture Design

1. System Architecture

   • Architecture Patterns
   • Scalability Design
   • Availability Assurance

2. Security Practices

   • Security Policies
   • Risk Control
   • Compliance Requirements

Development Guidelines

1. Coding Standards

   • Coding Standards
   • Naming Conventions
   • Documentation Requirements

2. Testing Guidelines

   • Testing Strategy
   • Test Case Design
   • Automated Testing

Enterprise Practices

1. Case Studies

   • Implementation Solutions
   • Technology Selection
   • Experience Summary

2. Performance Tuning

   • Optimization Strategies
   • Performance Testing
   • Practical Experience