问题
I am implementing VOIP application. I use this sample VOIP sample.
when a call changes status, I want to send an event from app service to main project in order to update UI, but I can not find any way to do it, I just can send a message from the main project to app service and receive a response.
So anyone can show me the way to send message from app service to main project ?
来源：https://stackoverflow.com/questions/39462097/send-events-from-appservice-to-main-project