Upstream (Ratpack API (2.0.0-rc-1))

Type Parameters:

T - the type of item emitted downstream
```
public interface Upstream<T>
```
An upstream asynchronous data source.
An upstream can be connected at any time to a Downstream, zero or more times. Once connected, the upstream will at some time in the future invoke one of the downstream's Downstream.success(T), Downstream.error(java.lang.Throwable), Downstream.complete() methods. Only one of these methods will be invoked per downstream that is connected, and only invoked once.
An upstream is the producer side of a Promise. Unlike a Publisher, it only produces one value and does not stream.
Multiple downstreams can connect to a single upstream.

See Also:

Promise.transform(Function)

- Method Summary
  
  All Methods Instance Methods Abstract Methods
  Modifier and Type Method Description
  
  void connect(Downstream<? super T> downstream)
  Connect the downstream.

- Method Detail
  - connect
```
void connect(Downstream<? super T> downstream)
      throws Exception
```
    Connect the downstream.
    
    Parameters:
    
    downstream - the downstream to emit data to
    
    Throws:
    
    Exception - any