Real-time data subscription

Ionic Framework
1

When on app A a product price is changed, app B should update the displayed price there, too, ideally as soon as possible. I would let the updated field flash briefly and show a temporary message that the value just has changed to notify the user.

websockets come to mind as a faster and more efficient alternative to classical polling.
For keeping everything simple I want to use something very high-level.

What libraries would you recommend?

2

It depends on your back-end. I use socket.io for nodejs and signalr for dot.net.

3

i’ve made the backed in java (spring), in my typescrit code (ionic with angular) i call a refresh function every X seconds, depending on the type of data i’m handling:

if i’m on a product page, i call the refresh method on “add to cart”, on “page enter” and every 30-60 secs if the user stays on the page.

For “less important data” i just call a refresher inside a setInterval, every 2-3 minutes

4

You are using REST HTTP API for the apps to communicate with the server?

Are you using an API generator or something else to bind the API to the app/react?

5

i’m using REST API, without any api generator

i just use import { HttpClient } from ‘@angular/common/http’;

and an example of function to get the items:

  doPostApplicationJsonBearer = (url: string, params: any, token: string) => {

    const headers = {
      "Accept": 'application/json',
      'Content-Type': 'application/json',
      'Authorization': 'Bearer ' + token
    };
    return this.http.post<any>(url, params, { headers });
  };

  doGetApplicationJsonBearer = (url: string, token: string) => {
    const headers = {
      'Accept': 'application/json',
      'Content-Type': "application/json",
      'Authorization': 'Bearer ' + token
    };

    return this.http.get<any>(url, { headers });

  };

i’ve made a service provider, i call the functions from the components of my app, like this for example:

    getLastOrders() {
    this.http.doGetApplicationJsonBearer(this.myEndpoints.getLastOrders, this.tokenValue).subscribe(res => {
        this.lastOrders = res;
        console.log(res);
    }

my data are stored on google cloud, a mysql database