Is it possible to call http API by websocket? - php

Question

I was asked me to make an api call using websocket with php Ratchet at work. Since I'm totally unfamilier with websocket so I googled and watched youtube videos to solve this problem, but The more I searched, the more I felt it is impossible to call api with websocket.
Am I missing something or is it really impossible to call api by websocket?
If it is possible, can you please show me an example how to do it
I know i might sound awkward since I don't have a solid understanding of websockets, English isn't even my first language, but i'm really desperate please help me

Answer 1

A REST API is fundamentally different from a WebSocket API.
REST API
Calls are made through HTTP(S). You can use AJAX (see here: https://en.wikipedia.org/wiki/Ajax_(programming)) to access HTTP endpoints directly from the browser. In JavaScript you would use the Fetch-API (see here: https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API) to make calls. Each and every call is stateless per definition. Cookies and special headers must be send with every request to create a context (e.g. user that is logged in).
Example (Client):
fetch('http://example.com/my-rest-api/endpoint1')
.then(response => response.json())
.then(data => console.log(data));
Example (Server):
app.get('/my-rest-api/endpoint1', handlerFunc);
WebSocket API
A stateful connection must be established between a client and a server. The client and server can exchange messages via the connection. Unlike a REST-API messages can be send bidirectional.
A high-level implementation of the WebSocket API is Socket.io.
An API can be designed by defining message types with payloads.
I also would not recommend to use PHP for a WS-API (even though there is a solution like Ratchet). Use a language/runtime that was developed for event-based use cases like this (e.g. nodeJS).
Example (Client):
const socket = SocketClass('example.com/my-websocket-api');
// variant 1 with callbacks
const response = socket.sendMessage('endpoint1', myData);
// variant 2 with message listener
socket.on('endpoint1Response', handlerFunc);
socket.sendMessage('endpoint1', myData);
Example (Server):
const serverSocket = SocketClass('/my-websocket-api');
serverSocket.on('connection', function (socket) {
// variant 1 with callbacks
socket.on('endpoint1', (data, callback) => {
callback(null, responseData);
});
// variant 2 with message listener
socket.on('endpoint1', (data, cb) => {
socket.emit('endpoint1Answer', responseData);
});
});