Merge pull request #294 from shivdeepak/main

add support for Streamable HTTP server

Author: cliffhall

client/src/App.tsx

@@ -81,9 +81,14 @@ const App = () => {
   const [sseUrl, setSseUrl] = useState<string>(() => {
     return localStorage.getItem("lastSseUrl") || "http://localhost:3001/sse";
   });
-  const [transportType, setTransportType] = useState<"stdio" | "sse">(() => {
+  const [transportType, setTransportType] = useState<
+    "stdio" | "sse" | "streamable-http"
+  >(() => {
     return (
-      (localStorage.getItem("lastTransportType") as "stdio" | "sse") || "stdio"
+      (localStorage.getItem("lastTransportType") as
+        | "stdio"
+        | "sse"
+        | "streamable-http") || "stdio"
     );
   });
   const [logLevel, setLogLevel] = useState<LoggingLevel>("debug");

client/src/components/Sidebar.tsx

@@ -39,8 +39,8 @@ import {
 
 interface SidebarProps {
   connectionStatus: ConnectionStatus;
-  transportType: "stdio" | "sse";
-  setTransportType: (type: "stdio" | "sse") => void;
+  transportType: "stdio" | "sse" | "streamable-http";
+  setTransportType: (type: "stdio" | "sse" | "streamable-http") => void;
   command: string;
   setCommand: (command: string) => void;
   args: string;
@@ -117,7 +117,7 @@ const Sidebar = ({
             </label>
             <Select
               value={transportType}
-              onValueChange={(value: "stdio" | "sse") =>
+              onValueChange={(value: "stdio" | "sse" | "streamable-http") =>
                 setTransportType(value)
               }
             >
@@ -127,6 +127,7 @@ const Sidebar = ({
               <SelectContent>
                 <SelectItem value="stdio">STDIO</SelectItem>
                 <SelectItem value="sse">SSE</SelectItem>
+                <SelectItem value="streamable-http">Streamable HTTP</SelectItem>
               </SelectContent>
             </Select>
           </div>

client/src/lib/hooks/useConnection.ts

@@ -42,7 +42,7 @@ import { getMCPServerRequestTimeout } from "@/utils/configUtils";
 import { InspectorConfig } from "../configurationTypes";
 
 interface UseConnectionOptions {
-  transportType: "stdio" | "sse";
+  transportType: "stdio" | "sse" | "streamable-http";
   command: string;
   args: string;
   sseUrl: string;

server/src/index.ts

@@ -14,11 +14,13 @@ import {
 } from "@modelcontextprotocol/sdk/client/stdio.js";
 import { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
 import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
+import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
 import express from "express";
 import { findActualExecutable } from "spawn-rx";
 import mcpProxy from "./mcpProxy.js";
 
 const SSE_HEADERS_PASSTHROUGH = ["authorization"];
+const STREAMABLE_HTTP_HEADERS_PASSTHROUGH = ["authorization"];
 
 const defaultEnvironment = {
   ...getDefaultEnvironment(),
@@ -94,6 +96,29 @@ const createTransport = async (req: express.Request): Promise<Transport> => {
 
     console.log("Connected to SSE transport");
     return transport;
+  } else if (transportType === "streamable-http") {
+    const headers: HeadersInit = {};
+
+    for (const key of STREAMABLE_HTTP_HEADERS_PASSTHROUGH) {
+      if (req.headers[key] === undefined) {
+        continue;
+      }
+
+      const value = req.headers[key];
+      headers[key] = Array.isArray(value) ? value[value.length - 1] : value;
+    }
+
+    const transport = new StreamableHTTPClientTransport(
+      new URL(query.url as string),
+      {
+        requestInit: {
+          headers,
+        },
+      },
+    );
+    await transport.start();
+    console.log("Connected to Streamable HTTP transport");
+    return transport;
   } else {
     console.error(`Invalid transport type: ${transportType}`);
     throw new Error("Invalid transport type specified");