GAE wait response from other source
You don't seem to have understood how web applications work. They don't wait for signals - or, rather, that's all they do. Every page served by a Web service is in response to a signal, ie a request. Your web service just needs to respond to normal requests in the normal way.
I don't know how to present the title more clearly. 
I want build a site on Google app engine (GAE), and one app on android.
The site on GAE should wait the signal which is from the app on android and handle the signal to do something. 
I don't know how to search the "keyword" on Google of waiting signal on GAE, or what method should I use. 
Is here have anyone who have some related experiment on it ?
Thank you very much.