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Jakarta EE Web Profile API
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/*
 * Copyright (c) 2011, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * 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 {@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.
 * 
 * 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
 * {@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:
 *
 *  * 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 {@code text/plain}
 * representation of the resource identified by {@code "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 {@link jakarta.ws.rs.client.Client} instance
 * create a {@link jakarta.ws.rs.client.WebTarget WebTarget} pointing at a Web resource
 * {@link jakarta.ws.rs.client.Invocation.Builder build} a request
 * submit a request to directly retrieve a response or get a prepared {@link jakarta.ws.rs.client.Invocation} for
 * later submission
 * 
 *
 * 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:
 *
 *  * // 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 {@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.
 *
 *  *   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(); }
 *   });
 * 
 */
package jakarta.ws.rs.client;