I have an asp.net c# desktop application which constantly polls for the database data every 5 minutes. This results in lots of load on the server, which in turn reduces its efficiency.
is there any technology in asp.net that supports publish subscribe model independent of database used? I know long polling is one of the alternatives. But I was looking for something which is event driven rather than long poll the data. Any help would be appreciated.
If you actually are using ASP.net, you can add the SignalR framework to establish a push channel to your desktop application.
On the server side, add the Microsoft.AspNet.SignalR nuget package (Install-Package Microsoft.AspNet.SignalR); on the client, add Microsoft.AspNet.SignalR.Client (Install-Package Microsoft.AspNet.SignalR.Client).
This way, you can notify all your clients whenever an update to the database has been made, like this:
public void AddCustomer(Customer customer)
{
using (var db = new CustomerContext)
{
db.Customers.Add(customer);
db.SaveChanges();
}
var hub = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
hub(customer.Id);
}
I think you are looking for something like Reactive Extensions.
http://msdn.microsoft.com/en-gb/data/gg577610.aspx
Under the covers it is all done with some implementation of polling, but the idea is to get the event loop monitoring the polling as efficient as possible.
Well typically you can do this with any messaging service.
Following .net messaging services come in mind:
I've no idea what or how much data you're dealing with here so this answer maybe far too much work unless you have a fairly small amount of data/database tables you're wanting to look at.
Instead of pulling sets of data every 5 minutes, add to your database a Table with a single datetime field. Then create triggers on the tables you want to monitor (on add/edit/delete/whatever). Have it so when the trigger is fired it updates the datetime in the table you created.
Change your desktop application to only pull that datetime value every 5 minutes, keep the value cached somewhere and compare it on each poll, if the datetime changes; your desktop application can then trigger the required data update.
