Curveball

Curveball is a framework for building web services in Node.js. It fullfills a similar role to Express and it's heavily inspired by Koa.

This web framework has the following goals:

• A minimal foundation.
• Completely written in and for TypeScript.
• Modern Ecmascript features.
• Async/await-based middleware.
• Native support for HTTP/2, including easy access to HTTP/2 Push.
• Native support for modern HTTP features, such as 103 Early Hints.

If you used Koa in the past, this is going to look pretty familiar. I'm a big fan of Koa myself and would recommend it over this project if you don't need any of the things this project offers.

Installation

npm install curveball

Getting started

Curveball only provides a basic framework. Using it means implementing or using curveball middleware. For example, if you want a router, use or build a Router middleware.

All of the following examples are written in typescript, but it is also possible to use the framework with plain javascript.

import { Application, Context } from 'curveball';

const app = new Application();
app.use((ctx: Context) => {

  ctx.response.status = 200;
  ctx.body = 'Hello world!'

});

Sending 1xx Informational responses

Curveball has native support for sending informational responses. Examples are:

• 100 Continue to let a client know even before the request completed that it makes sense to continue, or that it should break off the request.
• 102 Processing to periodically indicate that the server is still working on the response. This might not be very useful anymore.
• 103 Early Hints a new standard to let a client or proxy know early in the process that some headers might be coming, allowing clients or proxies to for example pre-fetch certain resources even before the initial request completes.

Here's an example of a middleware using 103 Early Hints:

import { Application, Context, Middleware } from 'curveball';

const app = new Curveball();
app.use(async (ctx: Context, next: Middleware) => {

  await ctx.response.sendInformational(103, {
    'Link' : [
      '</style.css> rel="prefetch" as="style"',
      '</script.js> rel="prefetch" as="script"',
    ]
  });
  await next();

});

API

The Context class

The Context object has the following properties:

• request - An instance of Request.
• response - An instance of Response.
• state - An object you can use to store request-specific state information. this object can be used to pass information between middlewares. A common example is that an authentication middlware might set 'currently logged in user' information here.

The Request interface

The Request interface represents the HTTP request. It has the following properties and methods:

• headers - An instance of Headers.
• path - The path of the request, for example /foo.html.
• method - For example, POST.
• requestTarget - The full requestTarget from the first line of the HTTP request.
• body - This might represent the body, but is initially just empty. It's up to middlewares to do something with raw body and parse it.
• rawBody() - This function uses the raw-body function to parse the body from the request into a string or Buffer. You can only do this once, so a middleware should use this function to populate body.
• query - An object containing the query parametes.
• type - The Content-Type without additional parameters.
• accepts - Uses the accepts package to do content-negotiation.

The Response interface

The Response interface represents a HTTP response. It has the following properties and methods:

• headers - An instance of Headers.
• status - The HTTP status code, for example 200 or 404.
• body - The response body. Can be a string, a buffer or an Object. If it's an object, the server will serialize it as JSON.
• type - The Content-Type without additional parameters.
• sendInformational(status, headers?) - Sends a 100 Continue, 102 Processing or 103 Early Hints response with optional headers.

The Headers inteface

The Headers interface represents HTTP headers for both the Request and Response.

It has the following methods:

• set(name, value) - Sets a HTTP header.
• get(name) - Returns the value of a HTTP header, or null.
• delete(name) - Deletes a HTTP header.
• append(name, value) - Adds a HTTP header, but doesn't erase an existing one with the same name.
• getAll() - Returns all HTTP headers as a key-value object.

Status

• Basic framework is in place.
• Many features still missing.