How to make a systemd-timer depend on internet connectivity?

I'm using systemd-timer to periodically run a script which consumes a webservice. Problem is, upon system resume or wake-up, internet connectivity would not get started right away but the timer gets fired and hence the script returns error (If the service waits for a couple of seconds, the script would run correctly and there would be no need to postpone the task until next run.) 1- How can I make it so that the timer (or the service associated with it), waits until net connectivity is available? 2- How can I make the timer (or service) not call the script when system is not online yet?