Implementation help needed for displaying recent updates om webapp in .net c#

The important point with web applications is that all updates are driven by the client. HTTP is stateless and operates on a model with clients asking for information and servers providing it.

So in your client code, you will need to have an AJAX request that asks for updates to the widgets. To save on traffic you could ask for updates to all four. The callback for that request should parse the server response and make appropriate adjustments to the widget display.

On the server, you need an easy way of determining whether a table has changed since a particular time. How exactly you do this depends on what the widgets and the data storage is, but it should be fast (i.e. no complex queries). When I did something similar (a PM box which updated its display when you received a message) the table I was using had an auto_increment key and the client code used the largest ID it had seen as the request token. A query like select id from pm where id>@clientrequestid or select id from pm order by id desc limit 1 will do the job of telling you whether there are updates and not hit the database hard; if there are updates, you can then do a more complex query to retrieve the data the client will need to render the update.

There is only one way to check for update when it comes to browser and web server, which is polling. You can do this using window.setTimeout (initiate AJAX request from client) or you can have timer on your page.

For better performance you should implement AJAX on your page when you are polling for data.

When call goes to backend check database for update and update the widgets with new content.

The Websocket API in HTML-5 provides better architecture to handle this kind of situation. Where server notify client (browser) for any changes. But I thing it if far from your actual requirement.

But for now polling is the best way to implement this kind of requirement.