Typically, the resource method accepting AsyncResponse will either store it and start a new thread to finish the request, the method will return and the invocation will be suspended, then eventually another thread (either the one which initiated an internal job or some other thread) will resume the suspended call. Note in this case the invocation will be suspended indefinitely until it is resumed.

Another approach is to have AsyncResponse suspended for a limited period of time only and also register a TimeoutHandler. The latter will be invoked when the invocation is resumed by the container after the timeout has expired and the handler will either complete the invocation or suspend it again till it is ready to finish it.

CompletionCallback can be registered with AsyncResponse to receive the notifications when the async response has been sent back.

This feature can help developers write very sophisticated asynchronous applications.

JAX-RS : Client API

JAX-RS 2.0 Client API
JAX-RS 2.0 and CXF specific API
Proxy-based API

Customizing proxies
Converting proxies to Web Clients and vice versa
Handling exceptions
Configuring proxies in Spring
Injecting proxies
Limitations
Working with user models

CXF WebClient API

Asynchronous invocations
Working with explicit collections
Handling exceptions
Configuring HTTP clients in Spring

XML-centric clients
Thread Safety
Configuring Clients at Runtime
Creating clients programmatically with no Spring dependencies
Configuring an HTTP Conduit from Spring
Clients and Authentication

Maven Dependency
JAX-RS 2.0 Client API

Overview
JAX-RS 2.0 and CXF specific API

Proxy-based API

Customizing proxies
Converting proxies to Web Clients and vice versa
Handling exceptions
Configuring proxies in Spring
Injecting proxies
Limitations
Working with user models

CXF WebClient API

Asynchronous invocations
Working with explicit collections
Handling exceptions
Configuring HTTP clients in Spring

XML-centric clients
Support for arbitrary HTTP methods for sync invocations.
Thread Sa fety
Configuring Clients at Runtime
Creating clients programmatically with no Spring dependencies
Configuring an HTTP Conduit from Spring
Clients and Authentication

Maven Dependency

<dependency>
+ <groupId>org.apache.cxf</groupId>
+ <artifactId>cxf-rt-rs-client</artifactId>
+ <version>3.0.0-milestone1</version>
+</dependency>

JAX-RS 2.0 Client API

CXF 3.0.0 implements JAX-RS 2.0 Client API. Internally it is implemented in terms of CXF specific WebClient.

JAX-RS 2.0 and CXF specific API

Overview

CXF proxy and WebClient client code has been retrofitted to support all the new JAX-RS 2.0 client constructs except for the client API itself.
-Specifically, JAX-RS 2.0 client filters, reader and writer interceptors, new exception classes and Response API all can be used in scope of working with proxy or WebClient API.

JAX-RS 2.0 and CXF specific API

Additionally, WebClient supports JAX-RS 2.0 AsyncInvoker interface and offers few shortcuts, please see more about it below.

CXF proxy and WebClient client code has been retrofitted to support JAX-RS 2.0 client filters, reader and writer interceptors, new exception classes and Response API.

Users can expect WebClient API maintained in the next CXF releases as it offers a light-weight fluent API alternative.

WebClient.getConfig(Object client) supports JAX-RS 2.0 WebTarget and Invocation.Builder for 2.0 clients to be able to get to the lower-level CXF configuration and set up the properties such as 'receiveTimeout', etc.

Proxy-based API

Asynchronous invocations

WebClient has several methods accepting JAX-RS 2.0 InvocationCallback and returning Future. Alternatively, users can also use WebClient.async() shortcut to work with a standard AsyncInvoker.

Working with explicit collections

WebClient supports GenericEntity and JAX-RS 2.0 GenericType directly and via JAX-RS 2.0 SyncInvoker and AsyncInvoker to make it easier to work with the explicit collections.