如何检查某个特定用户是否有互联网连接？

Question

I maintain a system built with Ruby on Rails. The client has asked me to prevent the system from working when a specific user has no internet connection.

How would you do it?

I need to check if a specific computer has internet connection! For instance if my pc or your pc or my mother's pc has no internet connection!

Answer 1

This has nothing to do with Ruby on Rails.

Is this user accessing a site that's on a local network but no outside internet access? If so you can have a before_filter or some kind of method on your homepage that tries to ping google.com or some other site outside of the LAN to check for internet.

Answer 2

Use Offline.js

1. Add offline.min.js file in your vendor/assets/javascripts
2. Require it in your app/assets/javascripts/application.js as //= require offline.min

3. Add the following code in the same application.js file

   $(document).ready(function() { Offline.check(); Offline.on('up', function() { $('a.btn').removeClass('disabled'); }); Offline.on('down', function() { $('a.btn').addClass('disabled'); }); });

This is in relevance to my code where I just disable all buttons when the connection goes off.

The default behaviour of Offline.js adds a overlay with a please wait message until the internet connection comes back on.

I prefer to handle it this way as it give better user experience. Disabling buttons is a subtle way of preventing a user from working.

Answer 3

So just to clarify, your Rails application exists for users to send food delivery requests to one specific user -- the shop preparing and sending that food out, presumably -- and you want users to be unable to create new delivery requests when the shop/owner isn't currently online?

The simplest way to implement this would be to have an Admin Dashboard area where the owner can click a button to 'open the shop' and allow new orders. The worry, then, is about the shop's connection going offline, resulting in customers whose order are never received. To get around that, you can have each customer order start in an 'unconfirmed' state; when a new order is submitted, the owner is notified, and he can click a button to confirm it, letting the user know that yes, their order has been seen and is being made (and their credit card can be charged then , if you have online payment). This is probably the most reliable solution because what you really want is confirmation that a human has acknowledged the order.

If you do want to tie it directly to online status, then you can have the Admin Dashboard page regularly check that it's being viewed. You could accomplish this with a websockets connection, see Action Cable introduced in Rails 5 . The Admin Dashboard page opens a websocket connection upon login; the new-connection event sets accepting_orders = true . The websocket disconnect event sets accepting_orders = false , which will happen soon after their connection is dropped (make sure to check the timeout settings). Without websockets, you could have a background HTTP request occurring on an interval; x seconds without receiving that request could cause Rails to stop accepting new orders.