A2A Agent注册与发现机制

分布式Agent系统中的智能服务发现与路由

本文档基于A2A Protocol设计理念,展示Agent注册与发现的技术实现

1. A2A Agent注册中心架构

1.1 分布式注册中心设计

A2A Protocol采用分布式Agent注册中心架构,确保高可用性和横向扩展能力。注册中心负责管理所有Agent的生命周期、能力信息和服务状态。

A2A注册中心核心组件

Agent Registry
  • • Agent基本信息存储
  • • 能力索引和查询
  • • 版本管理和兼容性
  • • 访问权限控制
Discovery Engine
  • • 智能能力匹配算法
  • • 多维度搜索索引
  • • 语义相似度计算
  • • 实时推荐系统
Load Balancer
  • • 智能路由策略
  • • 实时负载监控
  • • 故障自动切换
  • • 性能优化算法
Health Monitor
  • • Agent健康状态检查
  • • 性能指标收集
  • • 异常检测和告警
  • • 自动恢复机制

1.2 数据模型设计

Agent注册信息数据结构:

{
  "registryEntry": {
    "agentId": "kb-agent-prod-01",
    "registrationTime": "2024-12-19T10:30:00Z",
    "lastHeartbeat": "2024-12-19T11:45:30Z",
    "status": "ACTIVE",
    "agentCard": {
      // 完整的Agent Card信息
      "agentInfo": { ... },
      "capabilities": [ ... ],
      "endpoints": { ... }
    },
    "runtimeMetrics": {
      "currentLoad": 0.65,
      "averageResponseTime": 850,
      "activeConnections": 23,
      "memoryUsage": 0.42,
      "cpuUsage": 0.38
    },
    "networkInfo": {
      "datacenter": "us-west-2",
      "zone": "us-west-2a",
      "internalIP": "10.0.1.15",
      "publicEndpoint": "https://kb-agent.example.com"
    },
    "capabilities_index": {
      // 为快速查询优化的能力索引
      "search": {
        "keywords": ["knowledge", "search", "nlp", "semantic"],
        "inputTypes": ["text", "query"],
        "outputTypes": ["results", "json"],
        "performance": "high",
        "languages": ["zh-CN", "en-US"]
      }
    },
    "dependencies": {
      "required": ["vector-db-service", "nlp-processor"],
      "optional": ["translation-service"]
    },
    "configProfile": {
      "environment": "production",
      "version": "2.1.0",
      "features": ["semantic-search", "multi-language"]
    }
  }
}

2. Agent注册流程详解

2.1 注册生命周期

完整注册流程

1
预注册验证 (Pre-Registration)

验证Agent身份、检查权限、确认依赖服务可用性

POST /registry/validate → 验证AgentCard格式和完整性
2
正式注册 (Registration)

提交完整注册信息,分配Agent ID,建立监控连接

POST /registry/register → 创建注册条目并分配ID
3
能力索引 (Capability Indexing)

分析Agent能力,构建搜索索引,优化发现算法

内部处理 → 构建多维度搜索索引
4
健康检查 (Health Check)

启动定期健康检查,建立心跳机制,监控性能指标

WebSocket连接 → 实时状态监控
激活服务 (Service Activation)

Agent正式上线,开始接受服务请求,参与负载均衡

状态: ACTIVE → 开始处理A2A请求

2.2 注册API实现

Python Agent注册客户端示例:

import asyncio
import aiohttp
import json
from datetime import datetime
from typing import Dict, List, Optional

class A2ARegistryClient:
    """A2A Protocol Agent注册客户端"""
    
    def __init__(self, registry_url: str, agent_card: Dict):
        self.registry_url = registry_url
        self.agent_card = agent_card
        self.agent_id = None
        self.registration_token = None
        self.heartbeat_task = None
        
    async def register(self) -> bool:
        """注册Agent到A2A注册中心"""
        try:
            # 步骤1: 预验证
            validation_result = await self._validate_agent_card()
            if not validation_result["valid"]:
                raise Exception(f"Agent Card validation failed: {validation_result['errors']}")
            
            # 步骤2: 正式注册
            registration_data = {
                "agentCard": self.agent_card,
                "timestamp": datetime.utcnow().isoformat(),
                "requestedCapabilities": self._extract_capabilities(),
                "networkInfo": await self._gather_network_info()
            }
            
            async with aiohttp.ClientSession() as session:
                async with session.post(
                    f"{self.registry_url}/api/v1/agents/register",
                    json=registration_data,
                    headers={"Content-Type": "application/json"}
                ) as response:
                    
                    if response.status == 201:
                        result = await response.json()
                        self.agent_id = result["agentId"]
                        self.registration_token = result["token"]
                        
                        # 步骤3: 启动心跳
                        await self._start_heartbeat()
                        
                        print(f"Agent successfully registered with ID: {self.agent_id}")
                        return True
                    else:
                        error = await response.text()
                        raise Exception(f"Registration failed: {error}")
                        
        except Exception as e:
            print(f"Registration error: {e}")
            return False
    
    async def _validate_agent_card(self) -> Dict:
        """验证Agent Card格式和内容"""
        validation_data = {"agentCard": self.agent_card}
        
        async with aiohttp.ClientSession() as session:
            async with session.post(
                f"{self.registry_url}/api/v1/agents/validate",
                json=validation_data
            ) as response:
                return await response.json()
    
    def _extract_capabilities(self) -> List[str]:
        """提取Agent能力列表"""
        capabilities = []
        for cap in self.agent_card.get("capabilities", []):
            capabilities.append({
                "name": cap["name"],
                "inputTypes": self._analyze_schema_types(cap.get("inputSchema", {})),
                "outputTypes": self._analyze_schema_types(cap.get("outputSchema", {})),
                "keywords": self._extract_keywords(cap.get("description", "")),
                "performance": cap.get("performance", {})
            })
        return capabilities
    
    async def _gather_network_info(self) -> Dict:
        """收集网络和环境信息"""
        import psutil
        import socket
        
        return {
            "hostname": socket.gethostname(),
            "internalIP": socket.gethostbyname(socket.gethostname()),
            "systemInfo": {
                "cpu_count": psutil.cpu_count(),
                "memory_total": psutil.virtual_memory().total,
                "disk_total": psutil.disk_usage('/').total
            },
            "endpoint": self.agent_card["endpoints"]["primary"]
        }
    
    async def _start_heartbeat(self):
        """启动心跳机制"""
        async def heartbeat_loop():
            while True:
                try:
                    await self._send_heartbeat()
                    await asyncio.sleep(30)  # 30秒心跳间隔
                except Exception as e:
                    print(f"Heartbeat error: {e}")
                    await asyncio.sleep(5)  # 错误后短暂等待
        
        self.heartbeat_task = asyncio.create_task(heartbeat_loop())
    
    async def _send_heartbeat(self):
        """发送心跳信息"""
        import psutil
        
        heartbeat_data = {
            "agentId": self.agent_id,
            "timestamp": datetime.utcnow().isoformat(),
            "status": "ACTIVE",
            "metrics": {
                "cpu_usage": psutil.cpu_percent(interval=1),
                "memory_usage": psutil.virtual_memory().percent / 100,
                "active_connections": len(psutil.net_connections()),
                "uptime": datetime.utcnow().isoformat()
            }
        }
        
        async with aiohttp.ClientSession() as session:
            await session.post(
                f"{self.registry_url}/api/v1/agents/{self.agent_id}/heartbeat",
                json=heartbeat_data,
                headers={"Authorization": f"Bearer {self.registration_token}"}
            )

# 使用示例
async def main():
    # 定义Agent Card
    agent_card = {
        "agentInfo": {
            "name": "Knowledge Base Agent",
            "type": "knowledge-base",
            "version": "1.0.0",
            "description": "智能知识库检索Agent"
        },
        "capabilities": [
            {
                "name": "search",
                "description": "在知识库中搜索相关信息",
                "inputSchema": {
                    "type": "object",
                    "properties": {
                        "query": {"type": "string"},
                        "category": {"type": "string"}
                    }
                },
                "outputSchema": {
                    "type": "object",
                    "properties": {
                        "results": {"type": "array"}
                    }
                }
            }
        ],
        "endpoints": {
            "primary": "ws://localhost:8080/agent",
            "healthCheck": "http://localhost:8080/health"
        }
    }
    
    # 创建注册客户端并注册
    registry_client = A2ARegistryClient(
        registry_url="http://localhost:9000",
        agent_card=agent_card
    )
    
    success = await registry_client.register()
    if success:
        print("Agent注册成功,开始提供服务...")
        # 保持运行状态
        await asyncio.Event().wait()

if __name__ == "__main__":
    asyncio.run(main())

3. A2A Agent智能发现算法

3.1 多维度搜索策略

A2A Protocol实现了基于多个维度的智能Agent发现算法,能够根据请求的复杂性和上下文自动选择最合适的Agent。

能力匹配

  • • 精确能力名称匹配
  • • 语义相似度计算
  • • 输入输出类型兼容
  • • 参数结构匹配度
权重: 40%

性能评估

  • • 历史响应时间
  • • 当前负载水平
  • • 可用性评分
  • • 成功率统计
权重: 30%

地理位置

  • • 网络延迟优化
  • • 数据中心亲和性
  • • 区域合规要求
  • • 成本优化考虑
权重: 20%

3.2 发现算法实现

智能发现算法核心逻辑:

class A2AAgentDiscovery:
    """A2A Protocol智能Agent发现引擎"""
    
    def __init__(self, registry_client):
        self.registry = registry_client
        self.capability_embeddings = {}  # 能力向量索引
        self.performance_cache = {}      # 性能指标缓存
        
    async def discover_agents(self, 
                            requirement: Dict, 
                            context: Dict = None,
                            preferences: Dict = None) -> List[Dict]:
        """
        智能发现匹配的Agent
        
        Args:
            requirement: 能力需求描述
            context: 请求上下文信息  
            preferences: 选择偏好设置
        """
        
        # 步骤1: 能力匹配
        capability_matches = await self._match_capabilities(requirement)
        
        # 步骤2: 性能评估
        performance_scores = await self._evaluate_performance(capability_matches)
        
        # 步骤3: 地理位置优化
        location_scores = await self._calculate_location_scores(
            capability_matches, context
        )
        
        # 步骤4: 综合评分
        final_scores = self._calculate_composite_scores(
            capability_matches,
            performance_scores, 
            location_scores,
            preferences or {}
        )
        
        # 步骤5: 排序和筛选
        ranked_agents = self._rank_and_filter(final_scores, requirement)
        
        return ranked_agents[:10]  # 返回前10个最佳匹配
    
    async def _match_capabilities(self, requirement: Dict) -> List[Dict]:
        """能力匹配算法"""
        required_capability = requirement.get("capability")
        input_schema = requirement.get("inputSchema", {})
        
        # 从注册中心获取所有相关Agent
        all_agents = await self.registry.query_agents({
            "capabilities": required_capability,
            "status": "ACTIVE"
        })
        
        matches = []
        for agent in all_agents:
            for capability in agent["agentCard"]["capabilities"]:
                # 精确匹配
                if capability["name"] == required_capability:
                    match_score = 1.0
                else:
                    # 语义相似度匹配
                    match_score = await self._semantic_similarity(
                        required_capability, 
                        capability["name"],
                        capability.get("description", "")
                    )
                
                # 输入输出兼容性检查
                io_compatibility = self._check_io_compatibility(
                    input_schema, 
                    capability.get("inputSchema", {}),
                    capability.get("outputSchema", {})
                )
                
                if match_score > 0.6 and io_compatibility > 0.7:
                    matches.append({
                        "agent": agent,
                        "capability": capability,
                        "capability_score": match_score * io_compatibility,
                        "match_details": {
                            "semantic_score": match_score,
                            "io_compatibility": io_compatibility
                        }
                    })
        
        return matches
    
    async def _semantic_similarity(self, req_cap: str, agent_cap: str, description: str) -> float:
        """计算能力语义相似度"""
        # 使用预训练的语义向量模型
        req_embedding = await self._get_capability_embedding(req_cap)
        agent_embedding = await self._get_capability_embedding(f"{agent_cap} {description}")
        
        # 计算余弦相似度
        similarity = self._cosine_similarity(req_embedding, agent_embedding)
        return max(0.0, min(1.0, similarity))
    
    async def _evaluate_performance(self, matches: List[Dict]) -> Dict[str, float]:
        """性能评估算法"""
        performance_scores = {}
        
        for match in matches:
            agent_id = match["agent"]["agentId"]
            
            # 获取性能指标
            metrics = await self.registry.get_agent_metrics(agent_id)
            
            # 计算性能评分
            response_time_score = self._normalize_response_time(
                metrics.get("averageResponseTime", 1000)
            )
            
            load_score = 1.0 - metrics.get("currentLoad", 0.5)
            
            availability_score = metrics.get("availability", 0.99)
            
            success_rate_score = metrics.get("successRate", 0.95)
            
            # 综合性能评分
            performance_score = (
                response_time_score * 0.3 +
                load_score * 0.3 +
                availability_score * 0.2 +
                success_rate_score * 0.2
            )
            
            performance_scores[agent_id] = performance_score
            
        return performance_scores
    
    def _calculate_composite_scores(self, 
                                  matches: List[Dict],
                                  performance_scores: Dict[str, float],
                                  location_scores: Dict[str, float],
                                  preferences: Dict) -> List[Dict]:
        """计算综合评分"""
        
        # 默认权重
        weights = {
            "capability": 0.4,
            "performance": 0.3,
            "location": 0.2,
            "other": 0.1
        }
        
        # 根据偏好调整权重
        if preferences.get("prioritize") == "performance":
            weights["performance"] = 0.5
            weights["capability"] = 0.3
        elif preferences.get("prioritize") == "location":
            weights["location"] = 0.4
            weights["capability"] = 0.3
        
        scored_matches = []
        for match in matches:
            agent_id = match["agent"]["agentId"]
            
            composite_score = (
                match["capability_score"] * weights["capability"] +
                performance_scores.get(agent_id, 0.5) * weights["performance"] +
                location_scores.get(agent_id, 0.5) * weights["location"]
            )
            
            match["composite_score"] = composite_score
            scored_matches.append(match)
        
        return scored_matches

# 使用示例
async def discover_knowledge_agent():
    """发现知识库Agent示例"""
    registry_client = A2ARegistryClient("http://localhost:9000")
    discovery = A2AAgentDiscovery(registry_client)
    
    # 定义需求
    requirement = {
        "capability": "search",
        "inputSchema": {
            "type": "object",
            "properties": {
                "query": {"type": "string"},
                "language": {"type": "string"}
            }
        },
        "priority": "high",
        "timeout": 5000
    }
    
    # 上下文信息
    context = {
        "requestLocation": "us-west-2",
        "sessionId": "session_123",
        "userLanguage": "zh-CN"
    }
    
    # 偏好设置
    preferences = {
        "prioritize": "performance",
        "maxResults": 5,
        "includeBackup": True
    }
    
    # 执行发现
    agents = await discovery.discover_agents(requirement, context, preferences)
    
    for agent in agents:
        print(f"Agent: {agent['agent']['agentId']}")
        print(f"Score: {agent['composite_score']:.3f}")
        print(f"Capability: {agent['capability']['name']}")
        print("---")

4. A2A 能力匹配机制

智能能力匹配特性

🎯 精确匹配

  • • 能力名称完全匹配
  • • 输入参数类型检查
  • • 输出格式验证
  • • 版本兼容性确认

🧠 语义匹配

  • • 同义词识别
  • • 上下文理解
  • • 意图推理
  • • 模糊查询支持

⚡ 性能匹配

  • • 响应时间预估
  • • 负载容量评估
  • • SLA等级匹配
  • • 资源需求分析

🌐 上下文匹配

  • • 地理位置优化
  • • 时区感知
  • • 语言环境适配
  • • 业务场景契合

A2A注册中心工具

Agent发现器

智能搜索和发现可用的A2A Agent服务

体验工具 →

注册验证器

验证Agent Card格式和注册信息完整性

开始验证 →

性能监控

实时监控Agent性能和健康状态

查看监控 →