I want to create an application in C# with client and server sides. It will work over local network. Client sides must check for updates on a remote SQL Server. Lets say we've set update time interval to 2 seconds. If i have 20 client side applications, then they'll send query to the remote SQL Server every 2 sec and it will load server quite a lot. Now I want to know is there any way to reduce server load or it's only way to check for updates?
Sorry for my bad english. Thx in advance
From my point of view, there is no need to allow clients to connect the DB serer directly. There should be one more tier here which will only connect to the server and cache information about the updates. Your clients should connect to this additional information and work with the cached info.
UPDATE As far as I understand, the problem appears because all your clients ping your DB server every two seconds. The solution to this problem is to create a special module which will only have access to the DB server and asks it for the update. For example, every two seconds. If the update is ready, it should be able to fetch it from the DB and store. This is what I meant under the additional tier.
Now, let's return to your clients. They should be able to communicate with this module and get information from it about a ready update (this information is cached and thus it is really fast to obtain it. Also you needn't ping the server at every client request). If update is ready, fetch it to the client side and work on client side.
As for the communication between this additional tier and clients. Since you are working with .NET, I would suggest that you take a look at the WCF which, from my point of view, becomes a standard approach of implementing the between-process communication in .NET. There are a lot of information in the network about it, I will post the links shortly.
Here is my favorite WCF book: