René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Streamable HTTP transport hangs during initialization","articleBody":"The client hangs during the first `initialize` message to a (public) Shopify MCP `https://my-best-shoes.myshopify.com/api/mcp`\n\nI can successfully connect `https://my-best-shoes.myshopify.com/api/mcp` from `npx @modelcontextprotocol/inspector`.\n\nNote that #396 describes that the client transport hangs during sendNotification for `notifications/initialized`. In this case, the client hangs even earlier - during `initialize`.\n\nSteps to reproduce:\n```\nString url = \"https://my-best-shoes.myshopify.com/api\";\nMcpClientTransport transport = HttpClientStreamableHttpTransport.builder(url).endpoint(\"/mcp\").build();\n\nMcpSyncClient client = McpClient.sync(transport)\n    .requestTimeout(Duration.ofSeconds(20))\n    .initializationTimeout(Duration.ofSeconds(20))\n    .build();\n\ntry {\n    client.initialize();\n\n    McpSchema.ListToolsResult tools = client.listTools();\n    logger.log(Level.INFO, \"Available tools: {0}\", tools.tools());\n\n} catch (Exception e) {\n    logger.log(Level.SEVERE, \"Failed to initialize MCP client from DebugServlet\", e);\n}\n```","author":{"url":"https://github.com/andrey-star","@type":"Person","name":"andrey-star"},"datePublished":"2025-07-16T18:33:07.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/406/java-sdk/issues/406"}