koa-multifetch

A simple koa.js middleware to multiplex several HTTP requests into one. Very useful on mobile devices where latency can kill performance. Based on Facebook's Batch Requests philosophy, and inspired by multifetch for Express.

Installation

npm install koa-multifetch

After installing the package, mount the middleware on any URL, using koa-route. For example, to add /multi as a multifetch endpoint:

var multifetch = require('koa-multifetch')();
var koaRoute = require('koa-route');
app.use(koaRoute.post('/multi', multifetch));

By default koa-multifetch use relative url. In this example all request will be prepended with "/multi".

But koa-multifetch can take an object of options as parameter, object that can have two properties:

1. If you want to allow koa-multifetch to send request anywhere on your site, enable absoluteUrl option with absolute property by calling

var multifetch = require('koa-multifetch')({absolute: true}); // enable absolute url, absolute is false by default

2. If you want to force koa-multifetch to send request on a specific host (for exemple if you are behind a load balancer on level 7), enable custom host option with header_host property by calling

var multifetch = require('koa-multifetch')({header_host: 'http://localhost:3000'}); // set a custom host for multiFetch requests

koa-multifetch can be mounted both as a GET and POST route.

Usage

Send a request to the route where the middleware is listening, passing the requests to fetch in parallel as a JSON object in the request body. For instance, to fetch /products/1 and /users in parallel, make the following request:

POST /multi HTTP/1.1
Content-Type: application/json
{
    "product": "/products/1",
    "all_users": "/users"
}

The middleware will call both HTTP resources, and return a response with a composite body once all the requests are fetched:

{
    "product": {
        "code":"200",
        "headers":[
            { "name": "Content-Type", "value": "text/javascript; charset=UTF-8" }
        ],
        "body": "{ id: 1, name: \"ipad2\", stock: 34 }"
    },
    "all_users": {
        "code":"200",
        "headers":[
            { "name": "Content-Type", "value": "text/javascript; charset=UTF-8" }
        ],
        "body": "[{ id: 2459, login: \"john\" }, { id: 7473, login: \"jane\" }]"
    }
}

Any header present in the multifetch request will be automatically added to all sub-requests.

Tip: When mounted as a GET route, koa-multifetch reads the query parameters to determine the requests to fetch:

GET /multi?product=/product/1&all_users=/users HTTP/1.1

License

koa-multifetch is licensed under the MIT Licence, courtesy of marmelab.