🤝 Agent间通信协议：A2A协议实战指南

A2A（Agent-to-Agent）协议定义了多个AI Agent之间如何发现彼此、交换信息、协商任务和协同工作。它是构建多Agent系统的通信基础，让不同Agent框架中的Agent能够无缝协作。

🎯 A2A协议核心概念

通信模型

┌─────────────────────────────────────────────┐
│           A2A Communication Model            │
│                                              │
│  Agent A ──(发现)──→ Agent Registry          │
│  Agent A ──(邀请)──→ Agent B                 │
│  Agent B ──(接受)──→ Agent A                 │
│  Agent A ──(任务)──→ Agent B                 │
│  Agent B ──(结果)──→ Agent A                 │
│  Agent A ──(确认)──→ Agent B                 │
└─────────────────────────────────────────────┘

消息类型

🚀 在OpenClaw中使用A2A

1. 配置Agent注册

// agent-registry.yaml
registry:
  name: "My Agent Network"
  version: "1.0"
  
agents:
  - id: "researcher"
    name: "研究助手"
    description: "负责信息搜索和分析"
    capabilities:
      - web_search
      - document_analysis
      - data_extraction
    endpoint: "http://localhost:8001/a2a"
    
  - id: "writer"
    name: "写作助手"
    description: "负责内容创作和编辑"
    capabilities:
      - content_writing
      - copy_editing
      - translation
    endpoint: "http://localhost:8002/a2a"
    
  - id: "reviewer"
    name: "审查助手"
    description: "负责质量审查和反馈"
    capabilities:
      - quality_review
      - fact_check
      - style_check
    endpoint: "http://localhost:8003/a2a"

2. 实现Agent通信

import { A2AClient, A2AServer } from 'openclaw/a2a';

// Agent A: 任务分配者
const coordinator = new A2AClient({
  agentId: 'coordinator',
  registry: './agent-registry.yaml'
});

// 发现可用Agent
const agents = await coordinator.discover({
  capability: 'web_search'
});

// 邀请Agent协作
const invitation = await coordinator.invite(
  agents[0].id,
  {
    task: '研究OpenClaw最新功能',
    context: '为技术博客准备素材',
    deadline: '2026-05-13T08:00:00Z',
    priority: 'high'
  }
);

// 等待结果
const result = await invitation.waitForResult({
  timeout: 3600000  // 1小时超时
});

console.log(result.output);
console.log(result.tokenUsage);
console.log(result.duration);

3. 接收任务

// Agent B: 任务执行者
const server = new A2AServer({
  agentId: 'researcher',
  port: 8001,
  registry: './agent-registry.yaml',
  
  // 能力声明
  capabilities: ['web_search', 'document_analysis'],
  
  // 任务处理器
  handlers: {
    async handleInvitation(invitation) {
      // 决定是否接受任务
      if (invitation.task.matches(capabilities)) {
        return { accept: true };
      }
      return { accept: false, reason: '超出能力范围' };
    },
    
    async handleTask(task) {
      // 执行任务
      const agent = new Agent({ name: 'researcher' });
      const result = await agent.run(task.description);
      
      return {
        success: true,
        output: result.text,
        artifacts: result.files,
        tokenUsage: result.usage
      };
    },
    
    async handleCancel(taskId) {
      // 取消任务
      return { cancelled: true };
    }
  }
});

server.start();

🔧 高级模式

多Agent编排

// 编排多个Agent协同工作
const orchestrator = new A2AOrchestrator({
  registry: './agent-registry.yaml',
  
  // 工作流定义
  workflows: {
    blogPost: {
      steps: [
        {
          agent: 'researcher',
          task: '研究主题相关资料',
          output: 'research_notes'
        },
        {
          agent: 'writer',
          task: '基于研究笔记撰写文章',
          input: 'research_notes',
          output: 'draft_article'
        },
        {
          agent: 'reviewer',
          task: '审查文章质量',
          input: 'draft_article',
          output: 'review_feedback'
        },
        {
          agent: 'writer',
          task: '根据反馈修改文章',
          input: ['draft_article', 'review_feedback'],
          output: 'final_article'
        }
      ],
      
      // 并行执行
      parallel: {
        research: ['web_search', 'document_analysis'],
        review: ['fact_check', 'style_check']
      },
      
      // 重试策略
      retry: {
        maxAttempts: 3,
        backoff: 'exponential'
      },
      
      // 超时
      timeout: 7200000  // 2小时
    }
  }
});

// 执行工作流
const result = await orchestrator.run('blogPost', {
  topic: 'OpenClaw A2A协议详解',
  targetAudience: '开发者'
});

安全通信

// A2A安全配置
const server = new A2AServer({
  security: {
    // 认证
    authentication: {
      type: 'jwt',
      publicKey: './keys/public.pem',
      issuer: 'my-agent-network'
    },
    
    // 加密
    encryption: {
      enabled: true,
      algorithm: 'aes-256-gcm',
      keyExchange: 'ecdh'
    },
    
    // 授权
    authorization: {
      type: 'rbac',
      roles: {
        coordinator: ['invite', 'task', 'cancel'],
        worker: ['accept', 'result', 'event']
      }
    },
    
    // 速率限制
    rateLimit: {
      maxMessagesPerMinute: 60,
      maxConcurrentTasks: 5
    }
  }
});

🔗 相关资源