Data Communication betwwen Server Client

Dear All,

I wants to develop one application in which i wants to data communication between server and client where client should be POS.I mean there are POS and i wants to update data to server from POS.

·          Client should have periodic transfer for data

·          Either it should be connected to web service permanently or connect on periodic basis

·          Should have option to validate if internet is connected

·          If no internet than should attempt 3 times to connect to web service than try at scheduled time

·          Client application should have option of read text file, sql server/access and xml file.

·          Configuration should be done using .ini or config file

·          During data transfer if internet disconnected(or any other reason) than should revert (revoke the process) and bookmark the data for future transaction

·          I don't know if we can bulk transfer the data if yes than bulk should be the best option.