I have built a website with PHP + Apache + JS + HTML 5. Now there is a point where I have to tell the user every second if the server is connected and ready to receive data and/or internet connection is lost/available or whatever else which can tell the user to not to send data to server because of unavailability of Server or internet connection.
For this purpose I can either move to Long Polling with Ajax and keep pinging my server every second but surely this will cause alot of network overhead on my Apache Server where my clients are about tens of thousands live at a time so keep pinging the server is not a good option. Therefore, I decided to use WebSockets.
I have been googling for about 2 days but yet could not find enough good article to answer my 3 basic questions regarding WebSocket and Apache + PHP.
1) If once the WebSocket connection is made with server, then does it remain active like Long Polling with Server or what is the mechanism behind it? I mean how does WebSocket maintain its relation with server does it keep polling with server and hence there is always a connection between Client and Server?
2) If your answer to above question is yes then what network/IO overhead would be on server side if I use websockets because there is a continuous connection between Client and Server. And imagine if there are hundreds of thousands of clients online at a time what load will it create on Server Network or IO?
3) What is the Best approach to use WebSockets when using Apache + PHP on server? Any good article on this where I can study how to communicate with Apache Server using WebSockets? I found this question, but it doesn't answer well Using WebSocket on Apache server. In this question, it limits the experts to not to include any answer which has sysadmin tools, while I am asking for it if any required.
I have a VPS Server so tunning and installing some tools isn't a problem.
Any help would be highly appreciated. Thanks with Regards.
1) If once the WebSocket connection is made with server, then does it remain active like Long Polling with Server or what is the mechanism behind it? I mean how does WebSocket maintain its relation with server does it keep polling with server and hence there is always a connection between Client and Server?
Yes, it remains active and there is always a connection between Client and Server. However, the client needs to maintain the connection and on connection exceptions. In this case, it is your javascript code.
2) If your answer to above question is yes then what network/IO overhead would be on server side if I use websockets because there is a continuous connection between Client and Server. And imagine if there are hundreds of thousands of clients online at a time what load will it create on Server Network or IO?
WebSocket connections are handled on TCP/IP level and by definition, they are not resource consuming operations when there is no data going through the TCP tunnel. So rather than worrying about your CPU and memory conception, you need to worry about the limit on the number of connections. Consider using a load balancer for your socket connections and utilize multiple servers if you are expecting more than 10000 concurrent connections.
3) What is the Best approach to use WebSockets when using Apache + PHP on server? Any good article on this where I can study how to communicate with Apache Server using WebSockets? I found this question, but it doesn't answer well Using WebSocket on Apache server. In this question, it limits the experts to not to include any answer which has sysadmin tools, while I am asking for it if any required.
For such a use case of yours - getting the status of the server, I would suggest using a message broker rather than load this simple operation to Apache.
Please consider looking at mosquitto, hivemq or rabbitmq
All of them are supporting WebSockets and all of them have their pros and cons. Do the small proof of concepts over them and choose what is best for you.