How do I implement a Push-Pull web application

The data is either in files or databases.

I want to implement data grids which will pull data from files (either .h5, csv or xml) and sql server database and show them being updated in rea开发者_开发百科l time.

I don't want to implement a timer which has few seconds interval. I want to implement a pull push technology in asp.net/c#/silverlight which I could use?

Please guide how best to implement it and if there are any libraries available that I can use?

Try the PokeIn ASP.NET Comet Library.

Look into Comet. Also check out this question (and answers).

You could look into Websockets, be aware the end users will need to have a websocket enabled browser and also note the following from wiki

For the client side, WebSocket was to be implemented in Firefox 4, Google Chrome 4, Opera 11, and Safari 5, as well as the mobile version of Safari in iOS 4.2.1 However, although present, support is now disabled by default in Firefox and Opera because of concerns over security vulnerabilities

WCF tech in a publisher-subscriber or observer pattern. Or SQL Server Service Broker notifications with a SqlDependency object. Or CLR stored procs that notify clients from within the DB.