POST /buy where payload is: {'id':1, 'cant':1} and the res is: {'date':'31-07-2020'} (fake delivery date)
main starts all the services
server handles http reqs to /buy
server calls stock service with a rpc call
stock service callas delivery service with a rpc call
delivery service retuns fake delivery date to stock and stock sends date to server
curl -i -X POST -d '{"id": 1, "quantity":1}' http://localhost:8080/buy/
res json '{"delivery_date":"random string delivery date"}'