定期检查服务器更新

Question

I am designing an app that will have to periodically check a web address for updates. The updates will be in a MySQL database tables.

I know the idea way to do this, is to create a service that is constantly running and trying to check for an update periodically (lets say 10 seconds).

Below are some questions that are unclear to me as I start my quest to accomplish this task.

1. Do I need to manually do the check for an update everytime from the client to server ? (that is, take a value on the client side, send it to server side, and do a head to head comparison), OR, the php/MySQL server can send a notification that there is an update that took place.

2. I came across a RSS feature in several posts in SO, however those tend to be NEWS applications, mine is not anything like that. Does it help to use RSS feeds in here ?

3. I'm planning on doing the check every 10 seconds. This means that upon the install of the app and since the app is on the device (and as long as there is internet connectivity) I will keep on fetching the server. This tends to be bandwidth and ram/cpu consuming for the client side. How do big apps like Viber, WhatsApp manage to do so ?

4. Just thinking out loud - , in order to avoid such a hassle, I was thinking with each update on the server, send a notification to the user with a certain code, and do the math inside the onReceive, if the code was something related to an update, 1-not show the notification to the user, 2-run the server update check thing.

ideas ?

Answer 1

The trouble is traditional php/html systems are client centric (the client has to initiate all communications).

You might want to look into websockets, or node.js. These technologies will allow you to create a persistent connection between the server and its clients. This in turn will allow you to 'push' data to the client when appropriate, without the client having to ask for it every x amount of minutes.

Node.js Chat Example

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