JavaScript mim Runtime API

The JavaScript mim Runtime API provides the objects and methods available to your mim code at runtime. Every mim request handler receives three objects:

mimikModule.exports = (context, request, response) => {
    // context - runtime services (storage, http, env, info)
    // request - incoming HTTP request data
    // response - methods to send HTTP response
};

Handler Signature

Your mim exports a single function that mimOE calls for each incoming request:

import Router from 'router';

const app = Router({ mergeParams: true });

mimikModule.exports = (context, request, response) => {
    global.context = context;  // Make context available globally
    app(request, response, (e) => {
        response.end(JSON.stringify({ code: e ? 400 : 404, message: e || 'Not Found' }));
    });
};

app.get('/hello', (request, response) => {
    response.end('Hello World!');
});

app.get('/data', (request, response) => {
    const value = context.storage.getItem('myKey');
    response.end(JSON.stringify({ value }));
});

The Three Objects

context

The context object provides runtime services for your mim:

Property	Type	Description
context.http	object	HTTP client for outbound requests
context.storage	object	Persistent key-value storage
context.env	object	Environment variables passed at deployment
context.info	object	Metadata about the mim and node
context.dispatchWebSocketEvent	function	Dispatch WebSocket events (when enabled)

request

The request object contains the incoming HTTP request:

Property	Type	Description
request.url	string	Full URL including query string
request.method	string	HTTP method (GET, POST, etc.)
request.headers	object	HTTP headers (lowercase keys)
request.body	string	Request body (for POST/PUT)
request.authorization	string	Authorization header value

response

The response object is used to send the HTTP response:

Property/Method	Description
response.statusCode	Set HTTP status code (default: 200)
response.setHeader(key, value)	Set a response header
response.write(content)	Write to response stream
response.end(body)	Send response and close connection

Quick Examples

Simple GET endpoint

app.get('/status', (request, response) => {
    response.end(JSON.stringify({ status: 'ok' }));
});

POST with JSON body

app.post('/users', (request, response) => {
    const user = JSON.parse(request.body);
    context.storage.setItem('user:' + user.id, JSON.stringify(user));
    response.statusCode = 201;
    response.end(JSON.stringify({ created: true }));
});

Making outbound HTTP requests

app.get('/external', (request, response) => {
    context.http.request({
        url: 'https://api.example.com/data',
        success: (result) => {
            response.end(result.data);
        },
        error: (err) => {
            response.statusCode = 500;
            response.end(err.message);
        }
    });
});

Using environment variables

app.get('/config', (request, response) => {
    const apiKey = context.env.API_KEY;
    const debug = context.env.DEBUG === 'true';
    response.end(JSON.stringify({ debug }));
});

API Reference

Page	Description
context.http	HTTP client for outbound requests
context.storage	Persistent key-value storage with tagging, embeddings, and pagination
context.info	Node metadata and environment variables
context.dispatchWebSocketEvent	WebSocket event dispatch for real-time notifications
request	Incoming HTTP request object
response	HTTP response methods

Runtime Environment

Critical Understanding

The mimOE JavaScript runtime is NOT Node.js. It is a custom ES5-based runtime. Node.js built-in modules are not available.

ES5 with Transpilation

The runtime executes ES5 JavaScript, but you can write modern JavaScript and transpile it using Webpack with Babel:

// You can write modern JavaScript
const add = (a, b) => a + b;
const message = `Hello ${name}`;
const { data } = response;

// Webpack + Babel transpiles to ES6 for deployment

See the JavaScript mims guide for toolchain setup.

What's Available vs. What's Not

Available	Not Available
context.http	fetch, XMLHttpRequest
context.storage	fs, localStorage
console.log (debugging)	process, __dirname

For the full list of trade-offs and alternatives, see Design Trade-offs.

Related

• JavaScript mims: Development guide
• MCM API: Deploy and manage mims
• Architecture: How mims work