# http2-wrapper
> HTTP/2 client, just with the familiar `https` API
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This package was created to support HTTP/2 without the need to rewrite your code.
I recommend adapting to the [`http2`](https://nodejs.org/api/http2.html) module if possible - it's much simpler to use and has many cool features!
**Tip**: `http2-wrapper` is very useful when you rely on other modules that use the HTTP/1 API and you want to support HTTP/2.
**Pro Tip**: While the native `http2` doesn't have agents yet, you can use `http2-wrapper` Agents and still operate on the native HTTP/2 streams.
## Installation
> `$ npm install http2-wrapper`
> `$ yarn add http2-wrapper`
## Usage
```js
const http2 = require('http2-wrapper');
const options = {
hostname: 'nghttp2.org',
protocol: 'https:',
path: '/httpbin/post',
method: 'POST',
headers: {
'content-length': 6
}
};
const request = http2.request(options, response => {
console.log('statusCode:', response.statusCode);
console.log('headers:', response.headers);
const body = [];
response.on('data', chunk => {
body.push(chunk);
});
response.on('end', () => {
console.log('body:', Buffer.concat(body).toString());
});
});
request.on('error', console.error);
request.write('123');
request.end('456');
// statusCode: 200
// headers: [Object: null prototype] {
// ':status': 200,
// date: 'Fri, 27 Sep 2019 19:45:46 GMT',
// 'content-type': 'application/json',
// 'access-control-allow-origin': '*',
// 'access-control-allow-credentials': 'true',
// 'content-length': '239',
// 'x-backend-header-rtt': '0.002516',
// 'strict-transport-security': 'max-age=31536000',
// server: 'nghttpx',
// via: '1.1 nghttpx',
// 'alt-svc': 'h3-23=":4433"; ma=3600',
// 'x-frame-options': 'SAMEORIGIN',
// 'x-xss-protection': '1; mode=block',
// 'x-content-type-options': 'nosniff'
// }
// body: {
// "args": {},
// "data": "123456",
// "files": {},
// "form": {},
// "headers": {
// "Content-Length": "6",
// "Host": "nghttp2.org"
// },
// "json": 123456,
// "origin": "xxx.xxx.xxx.xxx",
// "url": "https://nghttp2.org/httpbin/post"
// }
```
## API
**Note:** The `session` option was renamed to `tlsSession` for better readability.
### http2.auto(url, options, callback)
Performs [ALPN](https://nodejs.org/api/tls.html#tls_alpn_and_sni) negotiation.
Returns a Promise giving proper `ClientRequest` instance (depending on the ALPN).
**Note**: The `agent` option represents an object with `http`, `https` and `http2` properties.
```js
const http2 = require('http2-wrapper');
const options = {
hostname: 'httpbin.org',
protocol: 'http:', // Note the `http:` protocol here
path: '/post',
method: 'POST',
headers: {
'content-length': 6
}
};
(async () => {
try {
const request = await http2.auto(options, response => {
console.log('statusCode:', response.statusCode);
console.log('headers:', response.headers);
const body = [];
response.on('data', chunk => body.push(chunk));
response.on('end', () => {
console.log('body:', Buffer.concat(body).toString());
});
});
request.on('error', console.error);
request.write('123');
request.end('456');
} catch (error) {
console.error(error);
}
})();
// statusCode: 200
// headers: { connection: 'close',
// server: 'gunicorn/19.9.0',
// date: 'Sat, 15 Dec 2018 18:19:32 GMT',
// 'content-type': 'application/json',
// 'content-length': '259',
// 'access-control-allow-origin': '*',
// 'access-control-allow-credentials': 'true',
// via: '1.1 vegur' }
// body: {
// "args": {},
// "data": "123456",
// "files": {},
// "form": {},
// "headers": {
// "Connection": "close",
// "Content-Length": "6",
// "Host": "httpbin.org"
// },
// "json": 123456,
// "origin": "xxx.xxx.xxx.xxx",
// "url": "http://httpbin.org/post"
// }
```
### http2.auto.protocolCache
An instance of [`quick-lru`](https://github.com/sindresorhus/quick-lru) used for ALPN cache.
There is a maximum of 100 entries. You can modify the limit through `protocolCache.maxSize` - note that the change will be visible globally.
### http2.request(url, options, callback)
Same as [`https.request`](https://nodejs.org/api/https.html#https_https_request_options_callback).
##### options.h2session
Type: `Http2Session`
The session used to make the actual request. If none provided, it will use `options.agent`.
### http2.get(url, options, callback)
Same as [`https.get`](https://nodejs.org/api/https.html#https_https_get_options_callback).
### new http2.ClientRequest(url, options, callback)
Same as [`https.ClientRequest`](https://nodejs.org/api/https.html#https_class_https_clientrequest).
### new http2.IncomingMessage(socket)
Same as [`https.IncomingMessage`](https://nodejs.org/api/https.html#https_class_https_incomingmessage).
### new http2.Agent(options)
**Note:** this is **not** compatible with the classic `http.Agent`.
Usage example:
```js
const http2 = require('http2-wrapper');
class MyAgent extends http2.Agent {
createConnection(origin, options) {
console.log(`Connecting to ${http2.Agent.normalizeOrigin(origin)}`);
return http2.Agent.connect(origin, options);
}
}
http2.get({
hostname: 'google.com',
agent: new MyAgent()
}, res => {
res.on('data', chunk => console.log(`Received chunk of ${chunk.length} bytes`));
});
```
#### options
Each option is assigned to each `Agent` instance and can be changed later.
##### timeout
Type: `number`
Default: `60000`
If there's no activity after `timeout` milliseconds, the session will be closed.
##### maxSessions
Type: `number`
Default: `Infinity`
The maximum amount of sessions in total.
##### maxFreeSessions
Type: `number`
Default: `10`
The maximum amount of free sessions in total. This only applies to sessions with no pending requests.
**Note:** It is possible that the amount will be exceeded when sessions have at least 1 pending request.
##### maxCachedTlsSessions
Type: `number`
Default: `100`
The maximum amount of cached TLS sessions.
#### Agent.normalizeOrigin(url)
Returns a string representing the origin of the URL.
#### agent.settings
Type: `object`
Default: `{enablePush: false}`
[Settings](https://nodejs.org/api/http2.html#http2_settings_object) used by the current agent instance.
#### agent.normalizeOptions([options](https://github.com/szmarczak/http2-wrapper/blob/master/source/agent.js))
Returns a string representing normalized options.
```js
Agent.normalizeOptions({servername: 'example.com'});
// => ':example.com'
```
#### agent.getSession(origin, options)
##### [origin](https://nodejs.org/api/http2.html#http2_http2_connect_authority_options_listener)
Type: `string` `URL` `object`
An origin used to create new session.
##### [options](https://nodejs.org/api/http2.html#http2_http2_connect_authority_options_listener)
Type: `object`
The options used to create new session.
Returns a Promise giving free `Http2Session`. If no free sessions are found, a new one is created.
#### agent.getSession([origin](#origin), [options](options-1), listener)
##### listener
Type: `object`
```
{
reject: error => void,
resolve: session => void
}
```
If the `listener` argument is present, the Promise will resolve immediately. It will use the `resolve` function to pass the session.
#### agent.request([origin](#origin), [options](#options-1), [headers](https://nodejs.org/api/http2.html#http2_headers_object), [streamOptions](https://nodejs.org/api/http2.html#http2_clienthttp2session_request_headers_options))
Returns a Promise giving `Http2Stream`.
#### agent.createConnection([origin](#origin), [options](#options-1))
Returns a new `TLSSocket`. It defaults to `Agent.connect(origin, options)`.
#### agent.closeFreeSessions()
Makes an attempt to close free sessions. Only sessions with 0 concurrent streams will be closed.
#### agent.destroy(reason)
Destroys **all** sessions.
#### Event: 'session'
```js
agent.on('session', session => {
// A new session has been created by the Agent.
});
```
## Proxy support
An example of a full-featured proxy server can be found [here](examples/proxy/server.js). It supports **mirroring, custom authorities and the CONNECT protocol**.
### Mirroring
To mirror another server we need to use only [`http2-proxy`](https://github.com/nxtedition/node-http2-proxy). We don't need the CONNECT protocol or custom authorities.
To see the result, just navigate to the server's address.
### HTTP/1 over HTTP/2
Since we don't care about mirroring, the server needs to support the CONNECT protocol in this case.
The client looks like this:
```js
const https = require('https');
const http2 = require('http2');
const session = http2.connect('https://localhost:8000', {
// For demo purposes only!
rejectUnauthorized: false
});
session.ref();
https.request('https://httpbin.org/anything', {
createConnection: options => {
return session.request({
':method': 'CONNECT',
':authority': `${options.host}:${options.port}`
});
}
}, response => {
console.log('statusCode:', response.statusCode);
console.log('headers:', response.headers);
const body = [];
response.on('data', chunk => {
body.push(chunk);
});
response.on('end', () => {
console.log('body:', Buffer.concat(body).toString());
session.unref();
});
}).end();
```
### HTTP/2 over HTTP/2
It's a tricky one! We cannot create an HTTP/2 session on top of an HTTP/2 stream. But... we can still specify the `:authority` header, no need to use the CONNECT protocol here.
The client looks like this:
```js
const http2 = require('../../source');
const {Agent} = http2;
class ProxyAgent extends Agent {
constructor(url, options) {
super(options);
this.origin = url;
}
request(origin, sessionOptions, headers, streamOptions) {
return super.request(this.origin, sessionOptions, {
...headers,
':authority': (new URL(origin)).host
}, streamOptions);
}
}
const request = http2.request({
hostname: 'httpbin.org',
protocol: 'https:',
path: '/anything',
agent: new ProxyAgent('https://localhost:8000'),
// For demo purposes only!
rejectUnauthorized: false
}, response => {
console.log('statusCode:', response.statusCode);
console.log('headers:', response.headers);
const body = [];
response.on('data', chunk => {
body.push(chunk);
});
response.on('end', () => {
console.log('body:', Buffer.concat(body).toString());
});
});
request.on('error', console.error);
request.end();
```
## Notes
- If you're interested in [WebSockets over HTTP/2](https://tools.ietf.org/html/rfc8441), then [check out this discussion](https://github.com/websockets/ws/issues/1458).
- [HTTP/2 sockets cannot be malformed](https://github.com/nodejs/node/blob/cc8250fab86486632fdeb63892be735d7628cd13/lib/internal/http2/core.js#L725), therefore modifying the socket will have no effect.
- You can make [a custom Agent](examples/push-stream/index.js) to support push streams.
## Benchmarks
CPU: Intel i7-7700k (governor: performance)
Server: H2O v2.2.5 [`h2o.conf`](h2o.conf)
Node: v14.5.0
Linux: 5.6.18-156.current
`auto` means `http2wrapper.auto`.
```
http2-wrapper x 12,181 ops/sec ±3.39% (75 runs sampled)
http2-wrapper - preconfigured session x 13,140 ops/sec ±2.51% (79 runs sampled)
http2-wrapper - auto x 11,412 ops/sec ±2.55% (78 runs sampled)
http2 x 16,050 ops/sec ±1.39% (86 runs sampled)
https - auto - keepalive x 12,288 ops/sec ±2.69% (79 runs sampled)
https - keepalive x 12,155 ops/sec ±3.32% (78 runs sampled)
https x 1,604 ops/sec ±2.03% (77 runs sampled)
http x 6,041 ops/sec ±3.82% (76 runs sampled)
Fastest is http2
```
`http2-wrapper`:
- 32% **less** performant than `http2`
- as performant as `https - keepalive`
- 100% **more** performant than `http`
`http2-wrapper - preconfigured session`:
- 22% **less** performant than `http2`
- 8% **more** performant than `https - keepalive`
- 118% **more** performant than `http`
`http2-wrapper - auto`:
- 41% **less** performant than `http2`
- 8% **less** performant than `https - keepalive`
- 89% **more** performant than `http`
`https - auto - keepalive`:
- 31% **less** performant than `http2`
- as performant as `https - keepalive`
- 103% **more** performant than `http`
## Related
- [`got`](https://github.com/sindresorhus/got) - Simplified HTTP requests
## License
MIT