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*
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*
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* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
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*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
The JAX-RS client API
The JAX-RS client API is a Java based API used to access Web resources. It is not restricted to resources implemented using JAX-RS. It provides a higher-level abstraction compared to a plain HTTP
communication API
as well as integration with the JAX-RS extension providers, in order to enable concise and efficient implementation of reusable client-side solutions that leverage existing and well established client-side implementations of HTTP-based communication.
The JAX-RS Client API encapsulates the Uniform Interface Constraint – a key constraint of the REST
architectural style – and associated data elements as client-side Java artifacts and supports a pluggable
architecture by defining multiple extension points.
Client API Bootstrapping and Configuration
The main entry point to the API is a ClientBuilder
that is used to bootstrap Client
instances - configurable
, heavy-weight objects that manage the underlying communication infrastructure and serve as the root objects for accessing any Web resource. The following example illustrates the bootstrapping and configuration of a Client
instance: Client client = ClientBuilder.newClient();
client.property("MyProperty", "MyValue")
.register(MyProvider.class)
.register(MyFeature.class);
Accessing Web Resources
A Web resource can be accessed using a fluent API in which method invocations are chained to configure and ultimately submit an HTTP request. The following example gets a text/plain
representation of the resource identified by "http://example.org/hello"
: Client client = ClientBuilder.newClient();
Response res = client.target("http://example.org/hello").request("text/plain").get();
Conceptually, the steps required to submit a request are the following:
- obtain an
Client
instance
- create a
WebTarget
pointing at a Web resource
build
a request
- submit a request to directly retrieve a response or get a prepared
Invocation
for later submission
As illustrated above, individual Web resources are in the JAX-RS Client API represented as resource targets. Each WebTarget
instance is bound to a concrete URI, e.g. "http://example.org/messages/123"
, or a URI template, e.g. "http://example.org/messages/{id}"
. That way a single target can either point at a particular resource or represent a larger group of resources (that e.g. share a common configuration) from which concrete resources can be later derived: // Parent target for all messages
WebTarget messages = client.target("http://example.org/messages/{id}");
// New target for http://example.org/messages/123
WebTarget msg123 = messages.resolveTemplate("id", 123);
// New target for http://example.org/messages/456
WebTarget msg456 = messages.resolveTemplate("id", 456);
Generic Invocations
An Invocation
is a request that has been prepared and is ready for execution. Invocations provide a generic interface that enables a separation of concerns between the creator and the submitter. In particular, the submitter does not need to know how the invocation was prepared, but only whether it should be executed synchronously or asynchronously. Invocation inv1 = client.target("http://example.org/atm/balance")
.queryParam("card", "111122223333").queryParam("pin", "9876")
.request("text/plain").buildGet();
Invocation inv2 = client.target("http://example.org/atm/withdrawal")
.queryParam("card", "111122223333").queryParam("pin", "9876")
.request().buildPost(text("50.0")));
Collection<Invocation> invs = Arrays.asList(inv1, inv2);
// Executed by the submitter
Collection<Response> ress = Collections.transform(invs, new F<Invocation, Response>() {
public Response apply(Invocation inv) {return inv.invoke(); }
});
/**
* <h2>The JAX-RS client API</h2>
* <p>
* The JAX-RS client API is a Java based API used to access Web resources. It is not restricted to resources implemented
* using JAX-RS. It provides a higher-level abstraction compared to a {@link java.net.HttpURLConnection plain HTTP
* communication API} as well as integration with the JAX-RS extension providers, in order to enable concise and
* efficient implementation of reusable client-side solutions that leverage existing and well established client-side
* implementations of HTTP-based communication.
* </p>
* The JAX-RS Client API encapsulates the Uniform Interface Constraint – a key constraint of the REST
* architectural style – and associated data elements as client-side Java artifacts and supports a pluggable
* architecture by defining multiple extension points.
*
* <h3>Client API Bootstrapping and Configuration</h3> The main entry point to the API is a
* {@link jakarta.ws.rs.client.ClientBuilder} that is used to bootstrap {@link jakarta.ws.rs.client.Client} instances -
* {@link jakarta.ws.rs.core.Configurable configurable}, heavy-weight objects that manage the underlying communication
* infrastructure and serve as the root objects for accessing any Web resource. The following example illustrates the
* bootstrapping and configuration of a {@code Client} instance:
*
* <pre>
* Client client = ClientBuilder.newClient();
*
* client.property("MyProperty", "MyValue")
* .register(MyProvider.class)
* .register(MyFeature.class);
* </pre>
*
* <h3>Accessing Web Resources</h3> A Web resource can be accessed using a fluent API in which method invocations are
* chained to configure and ultimately submit an HTTP request. The following example gets a {@code text/plain}
* representation of the resource identified by {@code "http://example.org/hello"}:
*
* <pre>
* Client client = ClientBuilder.newClient();
* Response res = client.target("http://example.org/hello").request("text/plain").get();
* </pre>
*
* Conceptually, the steps required to submit a request are the following:
* <ol>
* <li>obtain an {@link jakarta.ws.rs.client.Client} instance</li>
* <li>create a {@link jakarta.ws.rs.client.WebTarget WebTarget} pointing at a Web resource</li>
* <li>{@link jakarta.ws.rs.client.Invocation.Builder build} a request</li>
* <li>submit a request to directly retrieve a response or get a prepared {@link jakarta.ws.rs.client.Invocation} for
* later submission</li>
* </ol>
*
* As illustrated above, individual Web resources are in the JAX-RS Client API represented as resource targets. Each
* {@code WebTarget} instance is bound to a concrete URI, e.g. {@code "http://example.org/messages/123"}, or a URI
* template, e.g. {@code "http://example.org/messages/{id}"}. That way a single target can either point at a particular
* resource or represent a larger group of resources (that e.g. share a common configuration) from which concrete
* resources can be later derived:
*
* <pre>
* // Parent target for all messages
* WebTarget messages = client.target("http://example.org/messages/{id}");
*
* // New target for http://example.org/messages/123
* WebTarget msg123 = messages.resolveTemplate("id", 123);
*
* // New target for http://example.org/messages/456
* WebTarget msg456 = messages.resolveTemplate("id", 456);
* </pre>
*
* <h3>Generic Invocations</h3> An {@link jakarta.ws.rs.client.Invocation} is a request that has been prepared and is
* ready for execution. Invocations provide a generic interface that enables a separation of concerns between the
* creator and the submitter. In particular, the submitter does not need to know how the invocation was prepared, but
* only whether it should be executed synchronously or asynchronously.
*
* <pre>
* Invocation inv1 = client.target("http://example.org/atm/balance")
* .queryParam("card", "111122223333").queryParam("pin", "9876")
* .request("text/plain").buildGet();
* Invocation inv2 = client.target("http://example.org/atm/withdrawal")
* .queryParam("card", "111122223333").queryParam("pin", "9876")
* .request().buildPost(text("50.0")));
*
* Collection<Invocation> invs = Arrays.asList(inv1, inv2);
* // Executed by the submitter
* Collection<Response> ress = Collections.transform(invs, new F<Invocation, Response>() {
* public Response apply(Invocation inv) {return inv.invoke(); }
* });
* </pre>
*/
package jakarta.ws.rs.client;