feat: SSE server

perplexity-ask/index.ts

@@ -1,12 +1,12 @@
 #!/usr/bin/env node
 
 import { Server } from "@modelcontextprotocol/sdk/server/index.js";
-import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
 import {
   CallToolRequestSchema,
   ListToolsRequestSchema,
   Tool,
 } from "@modelcontextprotocol/sdk/types.js";
+import {createSSEServer} from "./sse-server.js";
 
 /**
  * Definition of the Perplexity Ask Tool.
@@ -294,9 +294,10 @@ server.setRequestHandler(CallToolRequestSchema, async (request) => {
  */
 async function runServer() {
   try {
-    const transport = new StdioServerTransport();
-    await server.connect(transport);
-    console.error("Perplexity MCP Server running on stdio with Ask, Research, and Reason tools");
+    const PORT = process.env.PORT || 3001
+    const sseServer = createSSEServer(server)
+    sseServer.listen(PORT)
+    console.error(`Perplexity MCP Server running on SSE and listening on port ${PORT} with Ask, Research, and Reason tools`);
   } catch (error) {
     console.error("Fatal error running server:", error);
     process.exit(1);

perplexity-ask/package.json

@@ -34,12 +34,14 @@
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.0.1",
     "axios": "^1.6.2",
-    "dotenv": "^16.3.1"
+    "dotenv": "^16.3.1",
+    "express": "^4.21.2"
   },
   "devDependencies": {
     "@types/node": "^20",
     "shx": "^0.3.4",
-    "typescript": "^5.6.2"
+    "typescript": "^5.6.2",
+    "@types/express": "^5.0.3"
   },
   "engines": {
     "node": ">=18"

perplexity-ask/sse-server.ts

@@ -0,0 +1,32 @@
+import { Server } from "@modelcontextprotocol/sdk/server/index.js";
+import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
+import express from "express";
+
+export function createSSEServer(mcpServer: Server) {
+    const app = express();
+
+    const transportMap = new Map<string, SSEServerTransport>();
+
+    app.get("/sse", async (req, res) => {
+        const transport = new SSEServerTransport("/messages", res);
+        transportMap.set(transport.sessionId, transport);
+        await mcpServer.connect(transport);
+    });
+
+    app.post("/messages", (req, res) => {
+        const sessionId = req.query.sessionId as string;
+        if (!sessionId) {
+            console.error('Message received without sessionId');
+            res.status(400).json({ error: 'sessionId is required' });
+            return;
+        }
+
+        const transport = transportMap.get(sessionId);
+
+        if (transport) {
+            transport.handlePostMessage(req, res);
+        }
+    });
+
+    return app;
+}