一台服务器上的多个客户端

Question

I am new to GUIs, and i have encountered a problem in my client-server program.

My program is like a "customer-support", where multiple clients can use it from different computers simultaneously.My problem is that when one client changes some info, its inserted into the db but the other client will not see it unless I add a "Refresh" button to my gui.

I want the gui to be dynamic and react to different clients actions. How can you come over this issue?

EDIT: 1. .net4, 2. sql-server, 3. The actions happends after a button click

Answer 1

Basically, you have two options: push or poll. Push (some central server announcing the change to all the listeners) is more immediate, but demands suitable infrastructure. It also depends on the number of clients you need to support, and how many events are passing through the system. Personally, I'm a big fan of redis pub/sub for this (it is actually what we use for the live updates here on stackexchange, coupled with web-sockets). But in some cases you can get the database to provide change notifications directly (personally I prefer not to use this). You may also be able to use events over something like WCF from a central app-server, but that depends on there only being one app-server, which doesn't sound like a good idea to me.

The other option is polling - ie have the application automatically query the system periodically (every minute perhaps) to see if the data being displayed has changed. If you can, using the timestamp/rowversion is a cheap way of doing this.