Return a small amount in a variable and a large amount by some other means. Data remains available until next run. A URL implies HTTP, that is, not UDP only. Yes, to say results are available. Intermediate results can go by push.
Final results can go by pull that causes script to run.
A script can push as it wishes. This is all we can do without specifying a language. For intermediate results script should be able to use standard notifications. A URL can be private between application and script. Time of day seems appropriate here.