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46.6. Asynchronous Processing on the Client
Overview
JAX-RS 2.0 supports asynchronous processing of invocations on the client side. Two different styles of asynchronous processing are supported: either using a
java.util.concurrent.Future<V> return value; or by registering an invocation callback.
Asynchronous invocation with Future<V> return value
Using the
Future<V> approach to asynchronous processing, you can invoke a client request asynchronously, as follows:
// Java
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Client;
import java.util.concurrent.Future;
import javax.ws.rs.core.Response;
...
Client client = ClientBuilder.newClient();
Future<Response> futureResp = client.target("http://example.org/bookstore/books/123")
.request("application/xml")
.async()
.get();
...
// At a later time, check (and wait) for the response:
Response resp = futureResp.get();
You can use a similar approach for typed responses. For example, to get a response of type,
BookInfo:
Client client = ClientBuilder.newClient();
Future<BookInfo> futureResp = client.target("http://example.org/bookstore/books/123")
.request("application/xml")
.async()
.get(BookInfo.class);
...
// At a later time, check (and wait) for the response:
BookInfo resp = futureResp.get();Asynchronous invocation with invocation callback
Instead of accessing the return value using a Future<V> object, you can define an invocation callback (using
javax.ws.rs.client.InvocationCallback<RESPONSE>), as follows:
// Java
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Client;
import java.util.concurrent.Future;
import javax.ws.rs.core.Response;
import javax.ws.rs.client.InvocationCallback;
...
Client client = ClientBuilder.newClient();
Future<Response> futureResp = client.target("http://example.org/bookstore/books/123")
.request("application/xml")
.async()
.get(
new InvocationCallback<Response>() {
@Override
public void completed(final Response resp) {
// Do something when invocation is complete
...
}
@Override
public void failed(final Throwable throwable) {
throwable.printStackTrace();
}
});
...
You can use a similar approach for typed responses:
// Java
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Client;
import java.util.concurrent.Future;
import javax.ws.rs.core.Response;
import javax.ws.rs.client.InvocationCallback;
...
Client client = ClientBuilder.newClient();
Future<BookInfo> futureResp = client.target("http://example.org/bookstore/books/123")
.request("application/xml")
.async()
.get(
new InvocationCallback<BookInfo>() {
@Override
public void completed(final BookInfo resp) {
// Do something when invocation is complete
...
}
@Override
public void failed(final Throwable throwable) {
throwable.printStackTrace();
}
});
...