AsyncHandler (Asynchronous Http Client 2.12.2 API)

Type Parameters:

T - Type of object returned by the Future.get()

All Known Subinterfaces:

ProgressAsyncHandler<T>, StreamedAsyncHandler<T>

All Known Implementing Classes:

AsyncCompletionHandler, AsyncCompletionHandlerBase, BodyDeferringAsyncHandler, ResumableAsyncHandler, TransferCompletionHandler, WebDavCompletionHandlerBase, WebSocketUpgradeHandler
```
public interface AsyncHandler<T>
```
An asynchronous handler or callback which gets invoked as soon as some data is available when processing an asynchronous response.
Callback methods get invoked in the following order:
1. onStatusReceived(HttpResponseStatus),
2. onHeadersReceived(HttpHeaders),
3. onBodyPartReceived(HttpResponseBodyPart), which could be invoked multiple times,
4. onTrailingHeadersReceived(HttpHeaders), which is only invoked if trailing HTTP headers are received
5. onCompleted(), once the response has been fully read.
Returning a AsyncHandler.State.ABORT from any of those callback methods will interrupt asynchronous response processing. After that, only onCompleted() is going to be called.
AsyncHandlers aren't thread safe. Hence, you should avoid re-using the same instance when doing concurrent requests. As an example, the following may produce unexpected results:
```
   AsyncHandler ah = new AsyncHandler() {....};
   AsyncHttpClient client = new AsyncHttpClient();
   client.prepareGet("http://...").execute(ah);
   client.prepareGet("http://...").execute(ah);
 
```
It is recommended to create a new instance instead.
Do NOT perform any blocking operations in any of these methods. A typical example would be trying to send another request and calling get() on its future. There's a chance you might end up in a dead lock. If you really need to perform a blocking operation, execute it in a different dedicated thread pool.

Nested Class Summary

Nested Classes
Modifier and Type Interface and Description

static class AsyncHandler.State

Nested Classes
Modifier and Type	Interface and Description
`static class`	`AsyncHandler.State`

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`AsyncHandler.State`	`onBodyPartReceived(HttpResponseBodyPart bodyPart)` Invoked as soon as some response body part are received.
`T`	`onCompleted()` Invoked once the HTTP response processing is finished.
`default void`	`onConnectionOffer(io.netty.channel.Channel connection)` Notify the callback when trying to offer a connection to the pool.
`default void`	`onConnectionPoolAttempt()` Notify the callback when trying to fetch a connection from the pool.
`default void`	`onConnectionPooled(io.netty.channel.Channel connection)` Notify the callback when a new connection was successfully fetched from the pool.
`AsyncHandler.State`	`onHeadersReceived(io.netty.handler.codec.http.HttpHeaders headers)` Invoked as soon as the HTTP headers have been received.
`default void`	`onHostnameResolutionAttempt(String name)` Notify the callback before hostname resolution
`default void`	`onHostnameResolutionFailure(String name, Throwable cause)` Notify the callback after hostname resolution failed.
`default void`	`onHostnameResolutionSuccess(String name, List<InetSocketAddress> addresses)` Notify the callback after hostname resolution was successful.
`default void`	`onRequestSend(NettyRequest request)` Notify the callback when a request is being written on the channel.
`default void`	`onRetry()` Notify the callback every time a request is being retried.
`AsyncHandler.State`	`onStatusReceived(HttpResponseStatus responseStatus)` Invoked as soon as the HTTP status line has been received
`default void`	`onTcpConnectAttempt(InetSocketAddress remoteAddress)` Notify the callback when trying to open a new connection.
`default void`	`onTcpConnectFailure(InetSocketAddress remoteAddress, Throwable cause)` Notify the callback after a failed connect.
`default void`	`onTcpConnectSuccess(InetSocketAddress remoteAddress, io.netty.channel.Channel connection)` Notify the callback after a successful connect
`void`	`onThrowable(Throwable t)` Invoked when an unexpected exception occurs during the processing of the response.
`default void`	`onTlsHandshakeAttempt()` Notify the callback before TLS handshake
`default void`	`onTlsHandshakeFailure(Throwable cause)` Notify the callback after the TLS failed
`default void`	`onTlsHandshakeSuccess(SSLSession sslSession)` Notify the callback after the TLS was successful
`default AsyncHandler.State`	`onTrailingHeadersReceived(io.netty.handler.codec.http.HttpHeaders headers)` Invoked when trailing headers have been received.

- Method Detail
  - onStatusReceived
```
AsyncHandler.State onStatusReceived(HttpResponseStatus responseStatus)
                             throws Exception
```
    Invoked as soon as the HTTP status line has been received
    
    Parameters:
    
    responseStatus - the status code and test of the response
    
    Returns:
    
    a AsyncHandler.State telling to CONTINUE or ABORT the current processing.
    
    Throws:
    
    Exception - if something wrong happens
  - onHeadersReceived
```
AsyncHandler.State onHeadersReceived(io.netty.handler.codec.http.HttpHeaders headers)
                              throws Exception
```
    Invoked as soon as the HTTP headers have been received.
    
    Parameters:
    
    headers - the HTTP headers.
    
    Returns:
    
    a AsyncHandler.State telling to CONTINUE or ABORT the current processing.
    
    Throws:
    
    Exception - if something wrong happens
  - onBodyPartReceived
```
AsyncHandler.State onBodyPartReceived(HttpResponseBodyPart bodyPart)
                               throws Exception
```
    Invoked as soon as some response body part are received. Could be invoked many times. Beware that, depending on the provider (Netty) this can be notified with empty body parts.
    
    Parameters:
    
    bodyPart - response's body part.
    
    Returns:
    
    a AsyncHandler.State telling to CONTINUE or ABORT the current processing. Aborting will also close the connection.
    
    Throws:
    
    Exception - if something wrong happens
  - onTrailingHeadersReceived
```
default AsyncHandler.State onTrailingHeadersReceived(io.netty.handler.codec.http.HttpHeaders headers)
                                              throws Exception
```
    Invoked when trailing headers have been received.
    
    Parameters:
    
    headers - the trailing HTTP headers.
    
    Returns:
    
    a AsyncHandler.State telling to CONTINUE or ABORT the current processing.
    
    Throws:
    
    Exception - if something wrong happens
  - onThrowable
```
void onThrowable(Throwable t)
```
    Invoked when an unexpected exception occurs during the processing of the response. The exception may have been produced by implementation of onXXXReceived method invocation.
    
    Parameters:
    
    t - a Throwable
  - onCompleted
```
T onCompleted()
       throws Exception
```
    Invoked once the HTTP response processing is finished.
    Gets always invoked as last callback method.
    
    Returns:
    
    T Value that will be returned by the associated Future
    
    Throws:
    
    Exception - if something wrong happens
  - onHostnameResolutionAttempt
```
default void onHostnameResolutionAttempt(String name)
```
    Notify the callback before hostname resolution
    
    Parameters:
    
    name - the name to be resolved
  - onHostnameResolutionSuccess
```
default void onHostnameResolutionSuccess(String name,
                                         List<InetSocketAddress> addresses)
```
    Notify the callback after hostname resolution was successful.
    
    Parameters:
    
    name - the name to be resolved
    
    addresses - the resolved addresses
  - onHostnameResolutionFailure
```
default void onHostnameResolutionFailure(String name,
                                         Throwable cause)
```
    Notify the callback after hostname resolution failed.
    
    Parameters:
    
    name - the name to be resolved
    
    cause - the failure cause
  - onTcpConnectAttempt
```
default void onTcpConnectAttempt(InetSocketAddress remoteAddress)
```
    Notify the callback when trying to open a new connection.
    Might be called several times if the name was resolved to multiple addresses and we failed to connect to the first(s) one(s).
    
    Parameters:
    
    remoteAddress - the address we try to connect to
  - onTcpConnectSuccess
```
default void onTcpConnectSuccess(InetSocketAddress remoteAddress,
                                 io.netty.channel.Channel connection)
```
    Notify the callback after a successful connect
    
    Parameters:
    
    remoteAddress - the address we try to connect to
    
    connection - the connection
  - onTcpConnectFailure
```
default void onTcpConnectFailure(InetSocketAddress remoteAddress,
                                 Throwable cause)
```
    Notify the callback after a failed connect.
    Might be called several times, or be followed by onTcpConnectSuccess when the name was resolved to multiple addresses.
    
    Parameters:
    
    remoteAddress - the address we try to connect to
    
    cause - the cause of the failure
  - onTlsHandshakeAttempt
```
default void onTlsHandshakeAttempt()
```
    Notify the callback before TLS handshake
  - onTlsHandshakeSuccess
```
default void onTlsHandshakeSuccess(SSLSession sslSession)
```
    Notify the callback after the TLS was successful
  - onTlsHandshakeFailure
```
default void onTlsHandshakeFailure(Throwable cause)
```
    Notify the callback after the TLS failed
    
    Parameters:
    
    cause - the cause of the failure
  - onConnectionPoolAttempt
```
default void onConnectionPoolAttempt()
```
    Notify the callback when trying to fetch a connection from the pool.
  - onConnectionPooled
```
default void onConnectionPooled(io.netty.channel.Channel connection)
```
    Notify the callback when a new connection was successfully fetched from the pool.
    
    Parameters:
    
    connection - the connection
  - onConnectionOffer
```
default void onConnectionOffer(io.netty.channel.Channel connection)
```
    Notify the callback when trying to offer a connection to the pool.
    
    Parameters:
    
    connection - the connection
  - onRequestSend
```
default void onRequestSend(NettyRequest request)
```
    Notify the callback when a request is being written on the channel. If the original request causes multiple requests to be sent, for example, because of authorization or retry, it will be notified multiple times.
    
    Parameters:
    
    request - the real request object as passed to the provider
  - onRetry
```
default void onRetry()
```
    Notify the callback every time a request is being retried.

Interface AsyncHandler<T>

Nested Class Summary

Method Summary

Method Detail

onStatusReceived

onHeadersReceived

onBodyPartReceived

onTrailingHeadersReceived

onThrowable

onCompleted

onHostnameResolutionAttempt

onHostnameResolutionSuccess

onHostnameResolutionFailure

onTcpConnectAttempt

onTcpConnectSuccess

onTcpConnectFailure

onTlsHandshakeAttempt

onTlsHandshakeSuccess

onTlsHandshakeFailure

onConnectionPoolAttempt

onConnectionPooled

onConnectionOffer

onRequestSend

onRetry