MCP Streamable HTTP 传输层的深度解析及实战分析

---

一、Streamable HTTP 传输层设计革新

1. 核心设计思想

• 协议融合：将 HTTP/1.1、HTTP/2 与 SSE 协议特性深度整合
• 动态协商：通过 HTTP Header 实现传输协议动态协商（X-MCP-Transport）
• 流式优先：默认启用流式传输，支持半双工通信
• 背压控制：基于 HTTP/2 流级流量控制实现智能速率调节

2. 与传统 HTTP+SSE 的对比

特性	传统 HTTP+SSE	Streamable HTTP
协议栈	单一 HTTP/1.1	HTTP/1.1/2 智能切换
流式支持	依赖特定 Content-Type	内置流式传输层
多路复用	不支持	HTTP/2 多路复用
背压控制	无	流级流量控制
协议协商	静态配置	动态 Header 协商

3. 协议栈架构

+----------------+     +-------------------+     +------------------+
|  Application    |     |   Streamable      |     |    HTTP/2        |
|  Layer (MCP)    |<----|  HTTP Transport   |<----|   Multiplexing   |
|                 |     |   Layer           |     | (可选)          |
+----------------+     +-------------------+     +------------------+|                      |                      ||  JSON Events         |  Binary Frames       |v                      v                      v
+----------------+     +-------------------+     +------------------+
|   TLS 1.3      |     |   HTTP/1.1        |     |   QUIC           |
+----------------+     +-------------------+     +------------------+

---

二、Spring AI Alibaba Streamable HTTP 实现

1. 核心组件架构

2. 关键代码实现

(1) 请求处理适配器

public class StreamableRequestAdapter {private final TransportMode transportMode;private final Decoder decoder;private final Encoder encoder;public StreamableRequestAdapter(MCPRequest request) {this.transportMode = determineTransportMode(request);this.decoder = createDecoder(transportMode);this.encoder = createEncoder(transportMode);}private TransportMode determineTransportMode(MCPRequest request) {if (request.getHeader("X-MCP-Transport").equals("binary")) {return TransportMode.HTTP2;}return request.getBodySize() > 1024 * 1024 ? TransportMode.SSE : TransportMode.JSON;}
}

(2) 流式响应处理器

@RestController
@RequestMapping("/mcp/v1")
public class MCPController {@PostMapping("/execute")public void executeCommand(@RequestBody MCPRequest request,HttpServletResponse response) {// 流式传输检测boolean isStreamable = request.getHeader("Accept-Stream").contains("text/event-stream");StreamableResponseWriter writer = new StreamableResponseWriter(response);writer.setContentType(isStreamable ? "text/event-stream" : "application/json");// 执行流式处理try (StreamableContext ctx = new StreamableContext(request, writer)) {executeTool(ctx);}}private void executeTool(StreamableContext ctx) {// 模拟流式响应for (int i = 0; i < 5; i++) {ctx.writeEvent(new MCPEvent().setStreamId(UUID.randomUUID().toString()).setChunk("Processing chunk " + i));}ctx.complete();}
}

3. Spring Boot 配置

spring:ai:mcp:transport:mode: AUTOhttp2:enabled: truemax-concurrent-streams: 512sse:chunk-size: 1024reconnect-interval: 5000security:enabled: truetoken: ${MCP_TOKEN:default-secret}

---

三、Higress 集成方案

1. 核心网关配置

http {stream {server {listen 8080;proxy_pass backend_servers;proxy_protocol on;proxy_http_version 2;}}server {listen 8081 http2;location /mcp/v1 {proxy_pass http://mcp-service;proxy_set_header X-MCP-Transport $http_x_mcp_transport;proxy_http_version 2;# 流式传输优化proxy_request_buffering off;proxy_buffering off;proxy_chunked_transfer_encoding on;# 安全策略proxy_set_header Authorization $http_authorization;proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;}}
}

2. WASM 智能路由模块

// higress-plugin.js
module.exports = {name: 'mcp-stream-optimizer',version: '1.0.0',async requestReceived(context) {const request = context.getRequest();const headers = request.getHeaders();// 流式传输检测逻辑if (headers['x-mcp-stream'] === 'required' && headers['content-type'] === 'application/octet-stream') {// 强制启用 HTTP/2context.setTransportProtocol('h2');context.setResponseHeader('X-MCP-Transport', 'binary');}}
};

---