503 lines
20 KiB
Plaintext
503 lines
20 KiB
Plaintext
"use strict";
|
|
// Run with: npx tsx src/examples/server/elicitationFormExample.ts
|
|
//
|
|
// This example demonstrates how to use form elicitation to collect structured user input
|
|
// with JSON Schema validation via a local HTTP server with SSE streaming.
|
|
// Form elicitation allows servers to request *non-sensitive* user input through the client
|
|
// with schema-based validation.
|
|
// Note: See also elicitationUrlExample.ts for an example of using URL elicitation
|
|
// to collect *sensitive* user input via a browser.
|
|
Object.defineProperty(exports, "__esModule", { value: true });
|
|
const node_crypto_1 = require("node:crypto");
|
|
const mcp_js_1 = require("../../server/mcp.js");
|
|
const streamableHttp_js_1 = require("../../server/streamableHttp.js");
|
|
const types_js_1 = require("../../types.js");
|
|
const express_js_1 = require("../../server/express.js");
|
|
// Factory to create a new MCP server per session.
|
|
// Each session needs its own server+transport pair to avoid cross-session contamination.
|
|
const getServer = () => {
|
|
// Create MCP server - it will automatically use AjvJsonSchemaValidator with sensible defaults
|
|
// The validator supports format validation (email, date, etc.) if ajv-formats is installed
|
|
const mcpServer = new mcp_js_1.McpServer({
|
|
name: 'form-elicitation-example-server',
|
|
version: '1.0.0'
|
|
}, {
|
|
capabilities: {}
|
|
});
|
|
/**
|
|
* Example 1: Simple user registration tool
|
|
* Collects username, email, and password from the user
|
|
*/
|
|
mcpServer.registerTool('register_user', {
|
|
description: 'Register a new user account by collecting their information',
|
|
inputSchema: {}
|
|
}, async () => {
|
|
try {
|
|
// Request user information through form elicitation
|
|
const result = await mcpServer.server.elicitInput({
|
|
mode: 'form',
|
|
message: 'Please provide your registration information:',
|
|
requestedSchema: {
|
|
type: 'object',
|
|
properties: {
|
|
username: {
|
|
type: 'string',
|
|
title: 'Username',
|
|
description: 'Your desired username (3-20 characters)',
|
|
minLength: 3,
|
|
maxLength: 20
|
|
},
|
|
email: {
|
|
type: 'string',
|
|
title: 'Email',
|
|
description: 'Your email address',
|
|
format: 'email'
|
|
},
|
|
password: {
|
|
type: 'string',
|
|
title: 'Password',
|
|
description: 'Your password (min 8 characters)',
|
|
minLength: 8
|
|
},
|
|
newsletter: {
|
|
type: 'boolean',
|
|
title: 'Newsletter',
|
|
description: 'Subscribe to newsletter?',
|
|
default: false
|
|
},
|
|
role: {
|
|
type: 'string',
|
|
title: 'Role',
|
|
description: 'Your primary role',
|
|
oneOf: [
|
|
{ const: 'developer', title: 'Developer' },
|
|
{ const: 'designer', title: 'Designer' },
|
|
{ const: 'manager', title: 'Manager' },
|
|
{ const: 'other', title: 'Other' }
|
|
],
|
|
default: 'developer'
|
|
},
|
|
interests: {
|
|
type: 'array',
|
|
title: 'Interests',
|
|
description: 'Select your areas of interest',
|
|
items: {
|
|
type: 'string',
|
|
enum: ['frontend', 'backend', 'mobile', 'devops', 'ai']
|
|
},
|
|
minItems: 1,
|
|
maxItems: 3
|
|
}
|
|
},
|
|
required: ['username', 'email', 'password']
|
|
}
|
|
});
|
|
// Handle the different possible actions
|
|
if (result.action === 'accept' && result.content) {
|
|
const { username, email, newsletter } = result.content;
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: `Registration successful!\n\nUsername: ${username}\nEmail: ${email}\nNewsletter: ${newsletter ? 'Yes' : 'No'}`
|
|
}
|
|
]
|
|
};
|
|
}
|
|
else if (result.action === 'decline') {
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: 'Registration cancelled by user.'
|
|
}
|
|
]
|
|
};
|
|
}
|
|
else {
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: 'Registration was cancelled.'
|
|
}
|
|
]
|
|
};
|
|
}
|
|
}
|
|
catch (error) {
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: `Registration failed: ${error instanceof Error ? error.message : String(error)}`
|
|
}
|
|
],
|
|
isError: true
|
|
};
|
|
}
|
|
});
|
|
/**
|
|
* Example 2: Multi-step workflow with multiple form elicitation requests
|
|
* Demonstrates how to collect information in multiple steps
|
|
*/
|
|
mcpServer.registerTool('create_event', {
|
|
description: 'Create a calendar event by collecting event details',
|
|
inputSchema: {}
|
|
}, async () => {
|
|
try {
|
|
// Step 1: Collect basic event information
|
|
const basicInfo = await mcpServer.server.elicitInput({
|
|
mode: 'form',
|
|
message: 'Step 1: Enter basic event information',
|
|
requestedSchema: {
|
|
type: 'object',
|
|
properties: {
|
|
title: {
|
|
type: 'string',
|
|
title: 'Event Title',
|
|
description: 'Name of the event',
|
|
minLength: 1
|
|
},
|
|
description: {
|
|
type: 'string',
|
|
title: 'Description',
|
|
description: 'Event description (optional)'
|
|
}
|
|
},
|
|
required: ['title']
|
|
}
|
|
});
|
|
if (basicInfo.action !== 'accept' || !basicInfo.content) {
|
|
return {
|
|
content: [{ type: 'text', text: 'Event creation cancelled.' }]
|
|
};
|
|
}
|
|
// Step 2: Collect date and time
|
|
const dateTime = await mcpServer.server.elicitInput({
|
|
mode: 'form',
|
|
message: 'Step 2: Enter date and time',
|
|
requestedSchema: {
|
|
type: 'object',
|
|
properties: {
|
|
date: {
|
|
type: 'string',
|
|
title: 'Date',
|
|
description: 'Event date',
|
|
format: 'date'
|
|
},
|
|
startTime: {
|
|
type: 'string',
|
|
title: 'Start Time',
|
|
description: 'Event start time (HH:MM)'
|
|
},
|
|
duration: {
|
|
type: 'integer',
|
|
title: 'Duration',
|
|
description: 'Duration in minutes',
|
|
minimum: 15,
|
|
maximum: 480
|
|
}
|
|
},
|
|
required: ['date', 'startTime', 'duration']
|
|
}
|
|
});
|
|
if (dateTime.action !== 'accept' || !dateTime.content) {
|
|
return {
|
|
content: [{ type: 'text', text: 'Event creation cancelled.' }]
|
|
};
|
|
}
|
|
// Combine all collected information
|
|
const event = {
|
|
...basicInfo.content,
|
|
...dateTime.content
|
|
};
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: `Event created successfully!\n\n${JSON.stringify(event, null, 2)}`
|
|
}
|
|
]
|
|
};
|
|
}
|
|
catch (error) {
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: `Event creation failed: ${error instanceof Error ? error.message : String(error)}`
|
|
}
|
|
],
|
|
isError: true
|
|
};
|
|
}
|
|
});
|
|
/**
|
|
* Example 3: Collecting address information
|
|
* Demonstrates validation with patterns and optional fields
|
|
*/
|
|
mcpServer.registerTool('update_shipping_address', {
|
|
description: 'Update shipping address with validation',
|
|
inputSchema: {}
|
|
}, async () => {
|
|
try {
|
|
const result = await mcpServer.server.elicitInput({
|
|
mode: 'form',
|
|
message: 'Please provide your shipping address:',
|
|
requestedSchema: {
|
|
type: 'object',
|
|
properties: {
|
|
name: {
|
|
type: 'string',
|
|
title: 'Full Name',
|
|
description: 'Recipient name',
|
|
minLength: 1
|
|
},
|
|
street: {
|
|
type: 'string',
|
|
title: 'Street Address',
|
|
minLength: 1
|
|
},
|
|
city: {
|
|
type: 'string',
|
|
title: 'City',
|
|
minLength: 1
|
|
},
|
|
state: {
|
|
type: 'string',
|
|
title: 'State/Province',
|
|
minLength: 2,
|
|
maxLength: 2
|
|
},
|
|
zipCode: {
|
|
type: 'string',
|
|
title: 'ZIP/Postal Code',
|
|
description: '5-digit ZIP code'
|
|
},
|
|
phone: {
|
|
type: 'string',
|
|
title: 'Phone Number (optional)',
|
|
description: 'Contact phone number'
|
|
}
|
|
},
|
|
required: ['name', 'street', 'city', 'state', 'zipCode']
|
|
}
|
|
});
|
|
if (result.action === 'accept' && result.content) {
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: `Address updated successfully!\n\n${JSON.stringify(result.content, null, 2)}`
|
|
}
|
|
]
|
|
};
|
|
}
|
|
else if (result.action === 'decline') {
|
|
return {
|
|
content: [{ type: 'text', text: 'Address update cancelled by user.' }]
|
|
};
|
|
}
|
|
else {
|
|
return {
|
|
content: [{ type: 'text', text: 'Address update was cancelled.' }]
|
|
};
|
|
}
|
|
}
|
|
catch (error) {
|
|
return {
|
|
content: [
|
|
{
|
|
type: 'text',
|
|
text: `Address update failed: ${error instanceof Error ? error.message : String(error)}`
|
|
}
|
|
],
|
|
isError: true
|
|
};
|
|
}
|
|
});
|
|
return mcpServer;
|
|
};
|
|
async function main() {
|
|
const PORT = process.env.PORT ? parseInt(process.env.PORT, 10) : 3000;
|
|
const app = (0, express_js_1.createMcpExpressApp)();
|
|
// Close sessions that have been idle for IDLE_MS, and keep at most MAX_SESSIONS open
|
|
const IDLE_MS = 30 * 60000;
|
|
const MAX_SESSIONS = 1000;
|
|
const sessions = new Map();
|
|
// Count open responses so a long-running request or a listening SSE stream is not treated as idle
|
|
const trackResponse = (session, res) => {
|
|
if (!res.socket || res.destroyed)
|
|
return;
|
|
session.open++;
|
|
res.on('close', () => {
|
|
session.open--;
|
|
session.lastActive = Date.now();
|
|
});
|
|
};
|
|
// Close sessions with nothing open and no activity for IDLE_MS
|
|
setInterval(() => {
|
|
const cutoff = Date.now() - IDLE_MS;
|
|
for (const { transport, open, lastActive } of sessions.values()) {
|
|
if (open === 0 && lastActive < cutoff)
|
|
transport.close().catch(console.error);
|
|
}
|
|
}, 60000).unref();
|
|
// MCP POST endpoint
|
|
const mcpPostHandler = async (req, res) => {
|
|
const sessionId = req.headers['mcp-session-id'];
|
|
if (sessionId) {
|
|
console.log(`Received MCP request for session: ${sessionId}`);
|
|
}
|
|
try {
|
|
const session = sessionId ? sessions.get(sessionId) : undefined;
|
|
let transport;
|
|
if (session) {
|
|
// Reuse existing transport for this session
|
|
transport = session.transport;
|
|
trackResponse(session, res);
|
|
}
|
|
else if (!sessionId && (0, types_js_1.isInitializeRequest)(req.body)) {
|
|
// New initialization request - create new transport
|
|
if (sessions.size >= MAX_SESSIONS) {
|
|
res.status(503).json({ jsonrpc: '2.0', error: { code: -32000, message: 'Too many open sessions' }, id: null });
|
|
return;
|
|
}
|
|
transport = new streamableHttp_js_1.StreamableHTTPServerTransport({
|
|
sessionIdGenerator: () => (0, node_crypto_1.randomUUID)(),
|
|
onsessioninitialized: sessionId => {
|
|
// Store the transport by session ID when session is initialized
|
|
console.log(`Session initialized with ID: ${sessionId}`);
|
|
sessions.set(sessionId, { transport, open: 0, lastActive: Date.now() });
|
|
}
|
|
});
|
|
// Set up onclose handler to clean up transport when closed
|
|
transport.onclose = () => {
|
|
const sid = transport.sessionId;
|
|
if (sid && sessions.has(sid)) {
|
|
console.log(`Transport closed for session ${sid}, removing from sessions map`);
|
|
sessions.delete(sid);
|
|
}
|
|
};
|
|
// Create a new server per session and connect it to the transport
|
|
const mcpServer = getServer();
|
|
await mcpServer.connect(transport);
|
|
await transport.handleRequest(req, res, req.body);
|
|
return;
|
|
}
|
|
else if (sessionId) {
|
|
// Unknown or expired session ID - the client should start a new session
|
|
res.status(404).json({ jsonrpc: '2.0', error: { code: -32001, message: 'Session not found' }, id: null });
|
|
return;
|
|
}
|
|
else {
|
|
// Invalid request - no session ID and not an initialization request
|
|
res.status(400).json({
|
|
jsonrpc: '2.0',
|
|
error: {
|
|
code: -32000,
|
|
message: 'Bad Request: No valid session ID provided'
|
|
},
|
|
id: null
|
|
});
|
|
return;
|
|
}
|
|
// Handle the request with existing transport
|
|
await transport.handleRequest(req, res, req.body);
|
|
}
|
|
catch (error) {
|
|
console.error('Error handling MCP request:', error);
|
|
if (!res.headersSent) {
|
|
res.status(500).json({
|
|
jsonrpc: '2.0',
|
|
error: {
|
|
code: -32603,
|
|
message: 'Internal server error'
|
|
},
|
|
id: null
|
|
});
|
|
}
|
|
}
|
|
};
|
|
app.post('/mcp', mcpPostHandler);
|
|
// Handle GET requests for SSE streams
|
|
const mcpGetHandler = async (req, res) => {
|
|
const sessionId = req.headers['mcp-session-id'];
|
|
if (!sessionId) {
|
|
res.status(400).send('Missing session ID');
|
|
return;
|
|
}
|
|
const session = sessions.get(sessionId);
|
|
if (!session) {
|
|
// Unknown or expired session ID - the client should start a new session
|
|
res.status(404).json({ jsonrpc: '2.0', error: { code: -32001, message: 'Session not found' }, id: null });
|
|
return;
|
|
}
|
|
console.log(`Establishing SSE stream for session ${sessionId}`);
|
|
trackResponse(session, res);
|
|
await session.transport.handleRequest(req, res);
|
|
};
|
|
app.get('/mcp', mcpGetHandler);
|
|
// Handle DELETE requests for session termination
|
|
const mcpDeleteHandler = async (req, res) => {
|
|
const sessionId = req.headers['mcp-session-id'];
|
|
if (!sessionId) {
|
|
res.status(400).send('Missing session ID');
|
|
return;
|
|
}
|
|
const session = sessions.get(sessionId);
|
|
if (!session) {
|
|
// Unknown or expired session ID - the client should start a new session
|
|
res.status(404).json({ jsonrpc: '2.0', error: { code: -32001, message: 'Session not found' }, id: null });
|
|
return;
|
|
}
|
|
console.log(`Received session termination request for session ${sessionId}`);
|
|
try {
|
|
trackResponse(session, res);
|
|
await session.transport.handleRequest(req, res);
|
|
}
|
|
catch (error) {
|
|
console.error('Error handling session termination:', error);
|
|
if (!res.headersSent) {
|
|
res.status(500).send('Error processing session termination');
|
|
}
|
|
}
|
|
};
|
|
app.delete('/mcp', mcpDeleteHandler);
|
|
// Start listening
|
|
app.listen(PORT, error => {
|
|
if (error) {
|
|
console.error('Failed to start server:', error);
|
|
process.exit(1);
|
|
}
|
|
console.log(`Form elicitation example server is running on http://localhost:${PORT}/mcp`);
|
|
console.log('Available tools:');
|
|
console.log(' - register_user: Collect user registration information');
|
|
console.log(' - create_event: Multi-step event creation');
|
|
console.log(' - update_shipping_address: Collect and validate address');
|
|
console.log('\nConnect your MCP client to this server using the HTTP transport.');
|
|
});
|
|
// Handle server shutdown
|
|
process.on('SIGINT', async () => {
|
|
console.log('Shutting down server...');
|
|
// Close all active transports to properly clean up resources
|
|
for (const [sessionId, { transport }] of sessions) {
|
|
try {
|
|
console.log(`Closing transport for session ${sessionId}`);
|
|
await transport.close();
|
|
sessions.delete(sessionId);
|
|
}
|
|
catch (error) {
|
|
console.error(`Error closing transport for session ${sessionId}:`, error);
|
|
}
|
|
}
|
|
console.log('Server shutdown complete');
|
|
process.exit(0);
|
|
});
|
|
}
|
|
main().catch(error => {
|
|
console.error('Server error:', error);
|
|
process.exit(1);
|
|
});
|
|
//# sourceMappingURL=elicitationFormExample.js.map |