From 27523d3ac31bc0aa80bb7411080a117eb655e458 Mon Sep 17 00:00:00 2001
From: chaoice <12228095+chaoice@users.noreply.github.com>
Date: Wed, 2 Apr 2025 10:40:48 +0800
Subject: [PATCH] Update HttpClientSseClientTransport.java

fix: switch HttpClient to HTTP/1.1 to prevent body loss with Python servers

This change modifies the HttpClient configuration to explicitly use HTTP_1_1 instead
of the default HTTP_2, resolving a critical compatibility issue with Python-based
servers (uvicorn/starlette) that cannot properly handle HTTP/2 upgrade requests with
bodies.

The issue occurs because:
1. Java's HttpClient attempts to upgrade to HTTP/2 (h2c) while simultaneously
   sending request bodies
2. Python servers (particularly with HttpToolsProtocol) prioritize protocol upgrade
   handling, causing the body parsing to be skipped or interrupted
3. This results in request bodies being lost during transmission
---
 .../client/transport/HttpClientSseClientTransport.java          | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mcp/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java b/mcp/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
index 696efdffd..962a38d2a 100644
--- a/mcp/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
+++ b/mcp/src/main/java/io/modelcontextprotocol/client/transport/HttpClientSseClientTransport.java
@@ -133,7 +133,7 @@ public HttpClientSseClientTransport(HttpClient.Builder clientBuilder, String bas
 		this.baseUri = baseUri;
 		this.sseEndpoint = sseEndpoint;
 		this.objectMapper = objectMapper;
-		this.httpClient = clientBuilder.connectTimeout(Duration.ofSeconds(10)).build();
+		this.httpClient = clientBuilder.version(HttpClient.Version.HTTP_1_1).connectTimeout(Duration.ofSeconds(10)).build();
 		this.sseClient = new FlowSseClient(this.httpClient);
 	}