hyper App Middleware

hyper Middleware allows you to extend the hyper App interface to support opinionated features, without having to modify the Core interface.

Middleware should be function that receives the App instance as a parameter and returns the App instance, creating a chain-able collection of middleware. For example, with express:

type HyperExpressAppMiddleware = (app: Express) => Express;

INFO

It is up to the hyper App implementation to properly apply the Middleware to itself.

In other words, the Middleware is specific to an App implementation

Middleware Examples

A common use-case is to enforce authN/Z on the hyper Server. Here is an example of a JWT verifying middleware when using an express-based App (See here):

import jwt from 'npm:express-jwt'

const auth = (app) => {
  app.use(jwt({
    secret: process.env.SECRET,
    algorithms: ['HS256']
  }).unless({ path: ['/', /^\/data$/] }))

  app.use('/data', jwt({
    secret: process.env.ADMIN_SECRET,
    algorithms: ['HS256']
  })

  app.use((err, req, res, next) => {
    if (err.name === 'UnauthorizedError') {
      res.status(401).send({ok: false, msg: 'not authorized'})
    }
  })

  return app
}

Because hyper is modular and in this case using express, you could use any express framework middleware to manage your authN/Z process. You can add more advanced security checks for each hyper Service resource or even for a specific Domain.

For example, let's say you only wanted certain clients to be able to create or destroy hyper Data Services on your hyper Server.

You would modify your Middleware to perform special checks based on those endpoints.

Other common use-cases:

• Throttling
• Additional Routes for other services, like email, or maybe serving files in a hyper Storage service

Applying Middleware

Once you've created your middleware, you'll want to apply it to your hyper Server

In the hyper Config file, you may specify an array of middleware. This middleware is then passed to the hyper App as services.middleware by hyper Core

import { auth } from "./auth.js";

export default {
  app: express,
  adapters: [
    /*...*/
  ],
  middleware: [auth],
};