feat(MssqlMcp/Node): Add multi-client HTTP/SSE transport and fix authentication fallback

MssqlMcp/Node/src/index.ts

@@ -3,8 +3,10 @@
 // External imports
 import * as dotenv from "dotenv";
 import sql from "mssql";
+import * as http from "http";
 import { Server } from "@modelcontextprotocol/sdk/server/index.js";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
+import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
 import {
   CallToolRequestSchema,
   ListToolsRequestSchema,
@@ -23,6 +25,7 @@ import { DescribeTableTool } from "./tools/DescribeTableTool.js";
 
 // MSSQL Database connection configuration
 // const credential = new DefaultAzureCredential();
+dotenv.config();
 
 // Globals for connection and token reuse
 let globalSqlPool: sql.ConnectionPool | null = null;
@@ -31,30 +34,54 @@ let globalTokenExpiresOn: Date | null = null;
 
 // Function to create SQL config with fresh access token, returns token and expiry
 export async function createSqlConfig(): Promise<{ config: sql.config, token: string, expiresOn: Date }> {
+  const trustServerCertificate = process.env.TRUST_SERVER_CERTIFICATE?.toLowerCase() === 'true';
+  const connectionTimeout = process.env.CONNECTION_TIMEOUT ? parseInt(process.env.CONNECTION_TIMEOUT, 10) : 30;
+
+  // Base configuration shared by both auth methods
+  const baseConfig = {
+    server: process.env.SERVER_NAME!,
+    database: process.env.DATABASE_NAME!,
+    options: {
+      encrypt: true,
+      trustServerCertificate
+    },
+    connectionTimeout: connectionTimeout * 1000, 
+  };
+
+  // ---------------------------------------------------------
+  // PATH A: Standard SQL Authentication (via .env)
+  // ---------------------------------------------------------
+  if (process.env.SQL_USER && process.env.SQL_PASSWORD) {
+    return {
+      config: {
+        ...baseConfig,
+        user: process.env.SQL_USER,
+        password: process.env.SQL_PASSWORD,
+      },
+      token: '',
+      expiresOn: new Date(Date.now() + 30 * 60 * 1000)
+    };
+  }
+
+  // ---------------------------------------------------------
+  // PATH B: Azure Active Directory Authentication (Browser Token)
+  // ---------------------------------------------------------
   const credential = new InteractiveBrowserCredential({
     redirectUri: 'http://localhost'
     // disableAutomaticAuthentication : true
   });
+
   const accessToken = await credential.getToken('https://database.windows.net/.default');
 
-  const trustServerCertificate = process.env.TRUST_SERVER_CERTIFICATE?.toLowerCase() === 'true';
-  const connectionTimeout = process.env.CONNECTION_TIMEOUT ? parseInt(process.env.CONNECTION_TIMEOUT, 10) : 30;
-
   return {
     config: {
-      server: process.env.SERVER_NAME!,
-      database: process.env.DATABASE_NAME!,
-      options: {
-        encrypt: true,
-        trustServerCertificate
-      },
+      ...baseConfig,
       authentication: {
         type: 'azure-active-directory-access-token',
         options: {
           token: accessToken?.token!,
         },
       },
-      connectionTimeout: connectionTimeout * 1000, // convert seconds to milliseconds
     },
     token: accessToken?.token!,
     expiresOn: accessToken?.expiresOnTimestamp ? new Date(accessToken.expiresOnTimestamp) : new Date(Date.now() + 30 * 60 * 1000)
@@ -156,11 +183,6 @@ async function runServer() {
   }
 }
 
-runServer().catch((error) => {
-  console.error("Fatal error running server:", error);
-  process.exit(1);
-});
-
 // Connect to SQL only when handling a request
 
 async function ensureSqlConnection() {
@@ -197,4 +219,112 @@ function wrapToolRun(tool: { run: (...args: any[]) => Promise<any> }) {
   };
 }
 
-[insertDataTool, readDataTool, updateDataTool, createTableTool, createIndexTool, dropTableTool, listTableTool, describeTableTool].forEach(wrapToolRun);
+[insertDataTool, readDataTool, updateDataTool, createTableTool, createIndexTool, dropTableTool, listTableTool, describeTableTool].forEach(wrapToolRun);
+
+// ==========================================
+// Transports & Server Startup
+// ==========================================
+
+// HTTP / Server-Sent Events Transport
+async function runHttpServer(port: number) {
+
+  // Map to store active client sessions
+  const activeTransports = new Map<string, SSEServerTransport>();
+
+  const httpServer = http.createServer(async (req, res) => {
+    // Parse the URL to get the path and query parameters
+    const parsedUrl = new URL(req.url || "/", `http://${req.headers.host}`);
+
+    // Add basic CORS headers for web clients
+    res.setHeader("Access-Control-Allow-Origin", "*");
+    res.setHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
+    res.setHeader("Access-Control-Allow-Headers", "Content-Type");
+
+    // Handle preflight requests
+    if (req.method === "OPTIONS") {
+      res.writeHead(200);
+      res.end();
+      return;
+    }
+
+    // ---------------------------------------------------------
+    // SSE Connection Endpoint (Handshake & Stream Start)
+    // ---------------------------------------------------------
+    if (req.method === "GET" && parsedUrl.pathname === "/sse") {
+      console.error("New client connecting...");
+
+      const transport = new SSEServerTransport("/messages", res as any);
+
+      // Connect this specific transport to the server instance
+      await server.connect(transport);
+
+      // Store the transport session so we can route POST messages to it later
+      activeTransports.set(transport.sessionId, transport);
+      console.error(`Client connected. Session ID: ${transport.sessionId}`);
+
+      // Crucial: Clean up memory when the client disconnects
+      res.on("close", () => {
+        console.error(`Client disconnected. Cleaning up Session ID: ${transport.sessionId}`);
+        activeTransports.delete(transport.sessionId);
+      });
+      return;
+    } 
+
+    // ---------------------------------------------------------
+    // Message Posting Endpoint (Receiving Client Tool Calls)
+    // ---------------------------------------------------------
+    if (req.method === "POST" && parsedUrl.pathname === "/messages") {
+      const sessionId = parsedUrl.searchParams.get("sessionId");
+
+      if (!sessionId) {
+        res.writeHead(400, { "Content-Type": "application/json" });
+        res.end(JSON.stringify({ error: "Missing sessionId in query parameters." }));
+        return;
+      }
+
+      const transport = activeTransports.get(sessionId);
+
+      if (transport) {
+        // Native Node http handles the stream internally in the SDK, 
+        // no need to parse req.body like in Express
+        await transport.handlePostMessage(req as any, res as any);
+      } else {
+        res.writeHead(404, { "Content-Type": "application/json" });
+        res.end(JSON.stringify({ error: "Session not found or expired. Reconnect to /sse." }));
+      }
+      return;
+    }
+
+    // 404 Fallback
+    res.writeHead(404);
+    res.end("Not Found");
+  });
+
+  httpServer.listen(port, () => {
+    console.error(`Multi-Client MSSQL MCP Server running on HTTP/SSE.`);
+    console.error(`Connect to SSE stream at: http://localhost:${port}/sse`);
+    console.error(`Send POST messages to:   http://localhost:${port}/messages?sessionId=...`);
+  });
+}
+
+// ==========================================
+// Execution Logic
+// ==========================================
+
+// Parse command line arguments
+const args = process.argv.slice(2);
+const isSSE = args.includes("--sse");
+const portArgIndex = args.indexOf("--port");
+const port = portArgIndex !== -1 ? parseInt(args[portArgIndex + 1], 10) : 3000;
+
+if (isSSE) {
+  runHttpServer(port).catch((error) => {
+    console.error("Fatal error running HTTP server:", error);
+    process.exit(1);
+  });
+} else {
+  runServer().catch((error) => {
+    console.error("Fatal error running stdio server:", error);
+    process.exit(1);
+  });
+}