Server and Client

Question

I'mdoing 2 applications installed in different hosts (Client n' Server). Both works on SQL Server. When there is no problem with the network connection the Client send data to the Server, but when there is a problem, the data are stored locally (in the Client) and when the connection is fine again, the data in the client are sent to the server. My problem is: How can I know when the connection is fine again? thanx in advance.