voder-proxy

Intercept requests to voder/tts_service and determine the appropriate backend to send them to. This acts as a load balancer of sorts.

make_service_fn ->

service_fn(|req : Request| -> ServiceFn<F,R>) It can return: - Ok(Response::new(Body::from("whatevs))) - Err("some explanation")

I'm doing matching on the route and method,

speak_proxy(req: Request, ... other args ...) -> BoxFut

 where BoxFut = Box<dyn Future<Item=Response<Body>, Error=hyper::Error> + Send>

 this also calls,

hyper_reverse_proxy::call( client_ip: IpAddr, forward_uri: &str, request: Request) -> BoxFut

Future is from futures-0.1.29

 boxed() -> BoxFut<> + Send
    * Use Box::new() to get around Send
 
 map() can turn Future<Item=T> into Future<Item=U>
   * Only called on success
   * Consumes the future
    * future::ok(1).map(|x| x+3) -> Ok(4)
   
 map_err() 
    * Only called on error
    * future::err(1).map_err(|x| x+3) -> Err(4)
 
 and_then() can create a future(?)
 
 then() runs the future, no matter what
    * Runs over Result<> type
    * Returns `IntoFuture` trait type; Result has this
    * future::ok(1).then(|x| match x { OK() => {} Err => { future::ok(...) } }
 
 and_then() execute another future 
    * Runs over Ok()/Item type.
 
 and_then() execute another future in success case
    * Runs over Ok()/Item type.
 
 or_else() execute another future in fail case 
    * Runs over Err()/Error type.
    
 inspect() look at the future, but pass it on!