WIP upgraded hyper-reverse-proxy, hyper, and futures

README.md

@@ -4,3 +4,54 @@ 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<Body>| -> 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<Body>, ... 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<Body>) -> 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!