org.jboss.resteasy.client.jaxrs.engines

Class ApacheHttpAsyncClient4Engine

java.lang.Object

org.jboss.resteasy.client.jaxrs.engines.ApacheHttpAsyncClient4Engine

All Implemented Interfaces:

Closeable, AutoCloseable, AsyncClientHttpEngine, ClientHttpEngine

public class ApacheHttpAsyncClient4Engine
extends Object
implements AsyncClientHttpEngine, Closeable

AsyncClientHttpEngine using apache http components HttpAsyncClient 4.

Some words of caution:

• Asynchronous IO means non-blocking IO utilizing few threads, typically at most as much threads as number of cores. As such, performance may profit from fewer thread switches and less memory usage due to fewer thread-stacks. But doing synchronous, blocking IO (the invoke-methods not returning a future) may suffer, because the data has to be transferred piecewiese to/from the io-threads.
• Request-Entities are fully buffered in memory, thus this engine is unsuitable for very large uploads.
• Response-Entities are buffered in memory, except if requesting a Response, InputStream or Reader as Result. Thus for large downloads or COMET one of these three return types must be requested, but there may be a performance penalty because the response-body is transferred piecewise from the io-threads. When using InvocationCallbacks, the response is always fully buffered in memory.
• InvocationCallbacks are called from within the io-threads and thus must not block or else the application may slow down to a halt. Reading the response is safe (because the response is buffered in memory), as are other async (and in-memory) Client-invocations (the submit-calls returning a future not containing Response, InputStream or Reader). Again, there must be no blocking IO inside InvocationCallback! (If you are wondering why not to allow blocking calls by wrapping InvocationCallbacks in extra threads: Because then the main advantage of async IO, less threading, is lost.)
• InvocationCallbacks may be called seemingly "after" the future-object returns. Thus, responses should be handled solely in the InvocationCallback.
• InvocationCallbacks will see the same result as the future-object and vice versa. Thus, if the invocationcallback throws an exception, the future-object will not see it. Another reason to handle responses only in the InvocationCallback.

Author:

Markus Kull

Nested Class Summary

Nested classes/interfaces inherited from interface org.jboss.resteasy.client.jaxrs.AsyncClientHttpEngine

AsyncClientHttpEngine.ResultExtractor<T>

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.http.impl.nio.client.CloseableHttpAsyncClient	client
protected boolean	closeHttpClient

Constructor Summary

Constructors

Constructor and Description
ApacheHttpAsyncClient4Engine(org.apache.http.impl.nio.client.CloseableHttpAsyncClient client, boolean closeHttpClient)

Method Summary

Modifier and Type	Method and Description
void	close()
HostnameVerifier	getHostnameVerifier() Needed for Client.getHostnameVerifier()
SSLContext	getSslContext() Needed for Client.getSslContext();
ClientResponse	invoke(ClientInvocation request)
<T> Future<T>	submit(ClientInvocation request, boolean buffered, InvocationCallback<T> callback, AsyncClientHttpEngine.ResultExtractor<T> extractor) Submits an asynchronous request.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

client

protected final org.apache.http.impl.nio.client.CloseableHttpAsyncClient client

closeHttpClient

protected final boolean closeHttpClient

Constructor Detail

ApacheHttpAsyncClient4Engine

public ApacheHttpAsyncClient4Engine(org.apache.http.impl.nio.client.CloseableHttpAsyncClient client,
                                    boolean closeHttpClient)

Method Detail

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface ClientHttpEngine

getSslContext

public SSLContext getSslContext()

Description copied from interface: ClientHttpEngine

Needed for Client.getSslContext();

Specified by:

getSslContext in interface ClientHttpEngine

Returns:

getHostnameVerifier

public HostnameVerifier getHostnameVerifier()

Description copied from interface: ClientHttpEngine

Needed for Client.getHostnameVerifier()

Specified by:

getHostnameVerifier in interface ClientHttpEngine

Returns:

invoke

public ClientResponse invoke(ClientInvocation request)

Specified by:

invoke in interface ClientHttpEngine

submit

public <T> Future<T> submit(ClientInvocation request,
                            boolean buffered,
                            InvocationCallback<T> callback,
                            AsyncClientHttpEngine.ResultExtractor<T> extractor)

Description copied from interface: AsyncClientHttpEngine

Submits an asynchronous request.

Specified by:

submit in interface AsyncClientHttpEngine

Parameters:

request - Request

buffered - buffer the response?

callback - Optional callback receiving the result, which is run inside the io-thread. may be null.

extractor - ResultExtractor for extracting a result out of a ClientResponse. Is run inside the io-thread

Returns:

Future with the result or Exception