107 lines
4.6 KiB
JavaScript
107 lines
4.6 KiB
JavaScript
"use strict";
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var __importDefault = (this && this.__importDefault) || function (mod) {
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return (mod && mod.__esModule) ? mod : { "default": mod };
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};
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Object.defineProperty(exports, "__esModule", { value: true });
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const node_crypto_1 = require("node:crypto");
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const mcp_js_1 = require("../../server/mcp.js");
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const express_js_1 = require("../../server/express.js");
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const streamableHttp_js_1 = require("../../server/streamableHttp.js");
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const inMemoryEventStore_js_1 = require("../shared/inMemoryEventStore.js");
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const cors_1 = __importDefault(require("cors"));
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// Factory to create a new MCP server per session.
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// Each session needs its own server+transport pair to avoid cross-session contamination.
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const getServer = () => {
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const server = new mcp_js_1.McpServer({
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name: 'sse-polling-example',
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version: '1.0.0'
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}, {
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capabilities: { logging: {} }
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});
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// Register a long-running tool that demonstrates server-initiated disconnect
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server.tool('long-task', 'A long-running task that sends progress updates. Server will disconnect mid-task to demonstrate polling.', {}, async (_args, extra) => {
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const sleep = (ms) => new Promise(resolve => setTimeout(resolve, ms));
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console.log(`[${extra.sessionId}] Starting long-task...`);
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// Send first progress notification
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await server.sendLoggingMessage({
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level: 'info',
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data: 'Progress: 25% - Starting work...'
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}, extra.sessionId);
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await sleep(1000);
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// Send second progress notification
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await server.sendLoggingMessage({
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level: 'info',
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data: 'Progress: 50% - Halfway there...'
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}, extra.sessionId);
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await sleep(1000);
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// Server decides to disconnect the client to free resources
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// Client will reconnect via GET with Last-Event-ID after the transport's retryInterval
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// Use extra.closeSSEStream callback - available when eventStore is configured
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if (extra.closeSSEStream) {
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console.log(`[${extra.sessionId}] Closing SSE stream to trigger client polling...`);
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extra.closeSSEStream();
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}
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// Continue processing while client is disconnected
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// Events are stored in eventStore and will be replayed on reconnect
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await sleep(500);
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await server.sendLoggingMessage({
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level: 'info',
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data: 'Progress: 75% - Almost done (sent while client disconnected)...'
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}, extra.sessionId);
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await sleep(500);
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await server.sendLoggingMessage({
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level: 'info',
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data: 'Progress: 100% - Complete!'
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}, extra.sessionId);
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console.log(`[${extra.sessionId}] Task complete`);
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return {
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content: [
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{
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type: 'text',
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text: 'Long task completed successfully!'
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}
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]
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};
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});
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return server;
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};
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// Set up Express app
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const app = (0, express_js_1.createMcpExpressApp)();
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app.use((0, cors_1.default)());
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// Create event store for resumability
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const eventStore = new inMemoryEventStore_js_1.InMemoryEventStore();
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// Track transports by session ID for session reuse
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const transports = new Map();
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// Handle all MCP requests
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app.all('/mcp', async (req, res) => {
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const sessionId = req.headers['mcp-session-id'];
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// Reuse existing transport or create new one
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let transport = sessionId ? transports.get(sessionId) : undefined;
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if (!transport) {
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transport = new streamableHttp_js_1.StreamableHTTPServerTransport({
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sessionIdGenerator: () => (0, node_crypto_1.randomUUID)(),
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eventStore,
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retryInterval: 2000, // Default retry interval for priming events
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onsessioninitialized: id => {
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console.log(`[${id}] Session initialized`);
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transports.set(id, transport);
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}
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});
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// Create a new server per session and connect it to the transport
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const server = getServer();
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await server.connect(transport);
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}
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await transport.handleRequest(req, res, req.body);
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});
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// Start the server
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const PORT = 3001;
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app.listen(PORT, () => {
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console.log(`SSE Polling Example Server running on http://localhost:${PORT}/mcp`);
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console.log('');
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console.log('This server demonstrates SEP-1699 SSE polling:');
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console.log('- retryInterval: 2000ms (client waits 2s before reconnecting)');
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console.log('- eventStore: InMemoryEventStore (events are persisted for replay)');
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console.log('');
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console.log('Try calling the "long-task" tool to see server-initiated disconnect in action.');
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});
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//# sourceMappingURL=ssePollingExample.js.map
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