Output interceptor

httpListener and webSocketListener allows to intercept outgoing messages via output$ attribute. Using HttpOutputEffect or WsOutputEffect you can grab an outgoing HTTP/Event response and map it into another form of outgoing message. Using this kind of response interceptor you can modify certain type of responses on demand. For example, in case of Accept: application/vnd.api+json you would like to adjust the response accordingly to fit the needs of JSON API specification.

HTTP:

import { HttpOutputEffect, httpListener } from '@marblejs/core';
const output$: HttpOutputEffect = res$ =>
res$.pipe(
map(res => ... ),
);
export default httpListener({
middlewares: [ ... ],
effects: [ ... ],
output$,
});

HTTP output interceptor allows you to grab the initial request via EffectMetadata.initiator. You can use it eg. for creating a compression middleware.

import { HttpOutputEffect } from '@marblejs/core';
const output$: HttpOutputEffect = (res$, _, { initiator }) =>
res$.pipe(
map(res => {
switch(initiator.headers['accept-encoding']) {
case 'br':
return ({
...res,
headers: { ...res.headers, 'Content-Encoding': 'br' },
body: res.body.pipe(zlib.createBrotliDecompress()),
});
case 'gzip':
return ({
...res,
headers: { ...res.headers, 'Content-Encoding': 'gzip' },
body: res.body.pipe(zlib.createGunzip()),
});
case 'deflate':
return ({
...res,
headers: { ...res.headers, 'Content-Encoding': 'deflate' },
body: res.body.pipe(zlib.createInflate()),
});
default:
return res;
}
}),
);

WebSockets:

import { WsOutputEffect, webSocket } from '@marblejs/websockets';
const output$: WsOutputEffect = event$ =>
event$.pipe(
map(event => ... ),
);
export default webSocketListener({
middlewares: [ ... ],
effects: [ ... ],
output$,
});