How do I get a Windows Form client to update every time a access table on webserver changes?

Question

I have a form with a list that shows information from a database. I want the list the update in run time (or almost real time) every time something changes in the database. These are the three ways I can think of to accomplish this:

Set up a timer on the client to check every few seconds: I know how to do this now, but it would involve making and closing a new connection to the database hundreds of times an hour, regardless of whether there was any change Build something sort of like a TCP/IP chat server, and every time a program updates the database it would also send a message to the TCP/IP server, which in turn would send a message to the client's form: I have no idea how to do this right now Create a web service that returns the date and time of when the last time the table was changed, and the client would compare that time to the last time the client updated: I could figure out how to build a web service, but I don't how to do this without making a connection to the database anyway The second option doesn't seem like it would be very reliable, and the first seems like it would consume more resources than necessary. Is there some way to tell the client every time there is a change in the database without making a connection every few seconds, or is it not that big of a deal to make that many connections to a database?

Answer 1

I would imagine connection pooling would make this a non-issue. Depending on your database, it probably won't even notice it.

Answer 2

Are you making the update to the database? Or is the update happening from an external source?

Generally, hundreds of updates per hour won't even bother the DB. Even Access, which is pretty slow, won't cause a performance issue.

Here's a rough idea if you really want to optimize it and you're doing the data updates. Store an application variable on the server side called, say, LastUpdateTime. When you make updates to the database, you can update the LastUpdateTime variable with the current time. Since LastUpdateTime is a very lightweight object in server memory, your clients can technically request the last update time hundreds if not thousands of times per second without any round trip to the database. Based on the last time the client retrieved new information vs. the last update time on the server, you can then go fetch the updated info.

Answer 3

We have a similar question Polling database for updates from C# application. Another idea (may be not a proper solution) would be to use Microsoft Sync Framework. You can use a timer to sync the DB.