/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.client;

import java.net.URI;
import java.util.Map;
import java.util.Set;

import org.springframework.core.ParameterizedTypeReference;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.RequestEntity;
import org.springframework.http.ResponseEntity;

/**
 * Interface specifying a basic set of RESTful operations.
 * Implemented by {@link RestTemplate}. Not often used directly, but a useful
 * option to enhance testability, as it can easily be mocked or stubbed.
 *
 * @author Arjen Poutsma
 * @author Juergen Hoeller
 * @since 3.0
 * @see RestTemplate
 * @see AsyncRestOperations
 */
public interface RestOperations {

	// GET

	/**
	 * Retrieve a representation by doing a GET on the specified URL.
	 * The response (if any) is converted and returned.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand the template
	 * @return the converted object
	 */
	<T> T getForObject(String url, Class<T> responseType, Object... uriVariables) throws RestClientException;

	/**
	 * Retrieve a representation by doing a GET on the URI template.
	 * The response (if any) is converted and returned.
	 * <p>URI Template variables are expanded using the given map.
	 * @param url the URL
	 * @param responseType the type of the return value
	 * @param uriVariables the map containing variables for the URI template
	 * @return the converted object
	 */
	<T> T getForObject(String url, Class<T> responseType, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Retrieve a representation by doing a GET on the URL .
	 * The response (if any) is converted and returned.
	 * @param url the URL
	 * @param responseType the type of the return value
	 * @return the converted object
	 */
	<T> T getForObject(URI url, Class<T> responseType) throws RestClientException;

	/**
	 * Retrieve an entity by doing a GET on the specified URL.
	 * The response is converted and stored in an {@link ResponseEntity}.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand the template
	 * @return the entity
	 * @since 3.0.2
	 */
	<T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Object... uriVariables) throws RestClientException;

	/**
	 * Retrieve a representation by doing a GET on the URI template.
	 * The response is converted and stored in an {@link ResponseEntity}.
	 * <p>URI Template variables are expanded using the given map.
	 * @param url the URL
	 * @param responseType the type of the return value
	 * @param uriVariables the map containing variables for the URI template
	 * @return the converted object
	 * @since 3.0.2
	 */
	<T> ResponseEntity<T> getForEntity(String url, Class<T> responseType, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Retrieve a representation by doing a GET on the URL .
	 * The response is converted and stored in an {@link ResponseEntity}.
	 * @param url the URL
	 * @param responseType the type of the return value
	 * @return the converted object
	 * @since 3.0.2
	 */
	<T> ResponseEntity<T> getForEntity(URI url, Class<T> responseType) throws RestClientException;


	// HEAD

	/**
	 * Retrieve all headers of the resource specified by the URI template.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param uriVariables the variables to expand the template
	 * @return all HTTP headers of that resource
	 */
	HttpHeaders headForHeaders(String url, Object... uriVariables) throws RestClientException;

	/**
	 * Retrieve all headers of the resource specified by the URI template.
	 * <p>URI Template variables are expanded using the given map.
	 * @param url the URL
	 * @param uriVariables the map containing variables for the URI template
	 * @return all HTTP headers of that resource
	 */
	HttpHeaders headForHeaders(String url, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Retrieve all headers of the resource specified by the URL.
	 * @param url the URL
	 * @return all HTTP headers of that resource
	 */
	HttpHeaders headForHeaders(URI url) throws RestClientException;


	// POST

	/**
	 * Create a new resource by POSTing the given object to the URI template, and returns the value of
	 * the {@code Location} header. This header typically indicates where the new resource is stored.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @param uriVariables the variables to expand the template
	 * @return the value for the {@code Location} header
	 * @see HttpEntity
	 */
	URI postForLocation(String url, Object request, Object... uriVariables) throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URI template, and returns the value of
	 * the {@code Location} header. This header typically indicates where the new resource is stored.
	 * <p>URI Template variables are expanded using the given map.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @param uriVariables the variables to expand the template
	 * @return the value for the {@code Location} header
	 * @see HttpEntity
	 */
	URI postForLocation(String url, Object request, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URL, and returns the value of the
	 * {@code Location} header. This header typically indicates where the new resource is stored.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @return the value for the {@code Location} header
	 * @see HttpEntity
	 */
	URI postForLocation(URI url, Object request) throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URI template,
	 * and returns the representation found in the response.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand the template
	 * @return the converted object
	 * @see HttpEntity
	 */
	<T> T postForObject(String url, Object request, Class<T> responseType, Object... uriVariables)
			throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URI template,
	 * and returns the representation found in the response.
	 * <p>URI Template variables are expanded using the given map.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand the template
	 * @return the converted object
	 * @see HttpEntity
	 */
	<T> T postForObject(String url, Object request, Class<T> responseType, Map<String, ?> uriVariables)
			throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URL,
	 * and returns the representation found in the response.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @param responseType the type of the return value
	 * @return the converted object
	 * @see HttpEntity
	 */
	<T> T postForObject(URI url, Object request, Class<T> responseType) throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URI template,
	 * and returns the response as {@link ResponseEntity}.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @param uriVariables the variables to expand the template
	 * @return the converted object
	 * @since 3.0.2
	 * @see HttpEntity
	 */
	<T> ResponseEntity<T> postForEntity(String url, Object request, Class<T> responseType, Object... uriVariables)
			throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URI template,
	 * and returns the response as {@link HttpEntity}.
	 * <p>URI Template variables are expanded using the given map.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @param uriVariables the variables to expand the template
	 * @return the converted object
	 * @since 3.0.2
	 * @see HttpEntity
	 */
	<T> ResponseEntity<T> postForEntity(String url, Object request, Class<T> responseType, Map<String, ?> uriVariables)
			throws RestClientException;

	/**
	 * Create a new resource by POSTing the given object to the URL,
	 * and returns the response as {@link ResponseEntity}.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be POSTed (may be {@code null})
	 * @return the converted object
	 * @since 3.0.2
	 * @see HttpEntity
	 */
	<T> ResponseEntity<T> postForEntity(URI url, Object request, Class<T> responseType) throws RestClientException;


	// PUT

	/**
	 * Create or update a resource by PUTting the given object to the URI.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be PUT (may be {@code null})
	 * @param uriVariables the variables to expand the template
	 * @see HttpEntity
	 */
	void put(String url, Object request, Object... uriVariables) throws RestClientException;

	/**
	 * Creates a new resource by PUTting the given object to URI template.
	 * <p>URI Template variables are expanded using the given map.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be PUT (may be {@code null})
	 * @param uriVariables the variables to expand the template
	 * @see HttpEntity
	 */
	void put(String url, Object request, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Creates a new resource by PUTting the given object to URL.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * @param url the URL
	 * @param request the Object to be PUT (may be {@code null})
	 * @see HttpEntity
	 */
	void put(URI url, Object request) throws RestClientException;


	// PATCH

	/**
	 * Update a resource by PATCHing the given object to the URI template,
	 * and return the representation found in the response.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * <p><b>NOTE: The standard JDK HTTP library does not support HTTP PATCH.
	 * You need to use the Apache HttpComponents or OkHttp request factory.</b>
	 * @param url the URL
	 * @param request the object to be PATCHed (may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand the template
	 * @return the converted object
	 * @since 4.3.5
	 * @see HttpEntity
	 * @see RestTemplate#setRequestFactory
	 * @see org.springframework.http.client.HttpComponentsAsyncClientHttpRequestFactory
	 * @see org.springframework.http.client.OkHttp3ClientHttpRequestFactory
	 */
	<T> T patchForObject(String url, Object request, Class<T> responseType, Object... uriVariables)
			throws RestClientException;

	/**
	 * Update a resource by PATCHing the given object to the URI template,
	 * and return the representation found in the response.
	 * <p>URI Template variables are expanded using the given map.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * <p><b>NOTE: The standard JDK HTTP library does not support HTTP PATCH.
	 * You need to use the Apache HttpComponents or OkHttp request factory.</b>
	 * @param url the URL
	 * @param request the object to be PATCHed (may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand the template
	 * @return the converted object
	 * @since 4.3.5
	 * @see HttpEntity
	 * @see RestTemplate#setRequestFactory
	 * @see org.springframework.http.client.HttpComponentsAsyncClientHttpRequestFactory
	 * @see org.springframework.http.client.OkHttp3ClientHttpRequestFactory
	 */
	<T> T patchForObject(String url, Object request, Class<T> responseType, Map<String, ?> uriVariables)
			throws RestClientException;

	/**
	 * Update a resource by PATCHing the given object to the URL,
	 * and return the representation found in the response.
	 * <p>The {@code request} parameter can be a {@link HttpEntity} in order to
	 * add additional HTTP headers to the request.
	 * <p><b>NOTE: The standard JDK HTTP library does not support HTTP PATCH.
	 * You need to use the Apache HttpComponents or OkHttp request factory.</b>
	 * @param url the URL
	 * @param request the object to be PATCHed (may be {@code null})
	 * @param responseType the type of the return value
	 * @return the converted object
	 * @since 4.3.5
	 * @see HttpEntity
	 * @see RestTemplate#setRequestFactory
	 * @see org.springframework.http.client.HttpComponentsAsyncClientHttpRequestFactory
	 * @see org.springframework.http.client.OkHttp3ClientHttpRequestFactory
	 */
	<T> T patchForObject(URI url, Object request, Class<T> responseType) throws RestClientException;



	// DELETE

	/**
	 * Delete the resources at the specified URI.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param uriVariables the variables to expand in the template
	 */
	void delete(String url, Object... uriVariables) throws RestClientException;

	/**
	 * Delete the resources at the specified URI.
	 * <p>URI Template variables are expanded using the given map.
	 *
	 * @param url the URL
	 * @param uriVariables the variables to expand the template
	 */
	void delete(String url, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Delete the resources at the specified URL.
	 * @param url the URL
	 */
	void delete(URI url) throws RestClientException;


	// OPTIONS

	/**
	 * Return the value of the Allow header for the given URI.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param uriVariables the variables to expand in the template
	 * @return the value of the allow header
	 */
	Set<HttpMethod> optionsForAllow(String url, Object... uriVariables) throws RestClientException;

	/**
	 * Return the value of the Allow header for the given URI.
	 * <p>URI Template variables are expanded using the given map.
	 * @param url the URL
	 * @param uriVariables the variables to expand in the template
	 * @return the value of the allow header
	 */
	Set<HttpMethod> optionsForAllow(String url, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Return the value of the Allow header for the given URL.
	 * @param url the URL
	 * @return the value of the allow header
	 */
	Set<HttpMethod> optionsForAllow(URI url) throws RestClientException;


	// exchange

	/**
	 * Execute the HTTP method to the given URI template, writing the given request entity to the request, and
	 * returns the response as {@link ResponseEntity}.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestEntity the entity (headers and/or body) to write to the request
	 * may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand in the template
	 * @return the response as entity
	 * @since 3.0.2
	 */
	<T> ResponseEntity<T> exchange(String url, HttpMethod method, HttpEntity<?> requestEntity,
			Class<T> responseType, Object... uriVariables) throws RestClientException;

	/**
	 * Execute the HTTP method to the given URI template, writing the given request entity to the request, and
	 * returns the response as {@link ResponseEntity}.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestEntity the entity (headers and/or body) to write to the request
	 * (may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand in the template
	 * @return the response as entity
	 * @since 3.0.2
	 */
	<T> ResponseEntity<T> exchange(String url, HttpMethod method, HttpEntity<?> requestEntity,
			Class<T> responseType, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Execute the HTTP method to the given URI template, writing the given request entity to the request, and
	 * returns the response as {@link ResponseEntity}.
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestEntity the entity (headers and/or body) to write to the request
	 * (may be {@code null})
	 * @param responseType the type of the return value
	 * @return the response as entity
	 * @since 3.0.2
	 */
	<T> ResponseEntity<T> exchange(URI url, HttpMethod method, HttpEntity<?> requestEntity,
			Class<T> responseType) throws RestClientException;

	/**
	 * Execute the HTTP method to the given URI template, writing the given
	 * request entity to the request, and returns the response as {@link ResponseEntity}.
	 * The given {@link ParameterizedTypeReference} is used to pass generic type information:
	 * <pre class="code">
	 * ParameterizedTypeReference&lt;List&lt;MyBean&gt;&gt; myBean = new ParameterizedTypeReference&lt;List&lt;MyBean&gt;&gt;() {};
	 * ResponseEntity&lt;List&lt;MyBean&gt;&gt; response = template.exchange(&quot;https://example.com&quot;,HttpMethod.GET, null, myBean);
	 * </pre>
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestEntity the entity (headers and/or body) to write to the
	 * request (may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand in the template
	 * @return the response as entity
	 * @since 3.2
	 */
	<T> ResponseEntity<T> exchange(String url,HttpMethod method, HttpEntity<?> requestEntity,
			ParameterizedTypeReference<T> responseType, Object... uriVariables) throws RestClientException;

	/**
	 * Execute the HTTP method to the given URI template, writing the given
	 * request entity to the request, and returns the response as {@link ResponseEntity}.
	 * The given {@link ParameterizedTypeReference} is used to pass generic type information:
	 * <pre class="code">
	 * ParameterizedTypeReference&lt;List&lt;MyBean&gt;&gt; myBean = new ParameterizedTypeReference&lt;List&lt;MyBean&gt;&gt;() {};
	 * ResponseEntity&lt;List&lt;MyBean&gt;&gt; response = template.exchange(&quot;https://example.com&quot;,HttpMethod.GET, null, myBean);
	 * </pre>
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestEntity the entity (headers and/or body) to write to the request
	 * (may be {@code null})
	 * @param responseType the type of the return value
	 * @param uriVariables the variables to expand in the template
	 * @return the response as entity
	 * @since 3.2
	 */
	<T> ResponseEntity<T> exchange(String url, HttpMethod method, HttpEntity<?> requestEntity,
			ParameterizedTypeReference<T> responseType, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Execute the HTTP method to the given URI template, writing the given
	 * request entity to the request, and returns the response as {@link ResponseEntity}.
	 * The given {@link ParameterizedTypeReference} is used to pass generic type information:
	 * <pre class="code">
	 * ParameterizedTypeReference&lt;List&lt;MyBean&gt;&gt; myBean = new ParameterizedTypeReference&lt;List&lt;MyBean&gt;&gt;() {};
	 * ResponseEntity&lt;List&lt;MyBean&gt;&gt; response = template.exchange(&quot;https://example.com&quot;,HttpMethod.GET, null, myBean);
	 * </pre>
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestEntity the entity (headers and/or body) to write to the request
	 * (may be {@code null})
	 * @param responseType the type of the return value
	 * @return the response as entity
	 * @since 3.2
	 */
	<T> ResponseEntity<T> exchange(URI url, HttpMethod method, HttpEntity<?> requestEntity,
			ParameterizedTypeReference<T> responseType) throws RestClientException;

	/**
	 * Execute the request specified in the given {@link RequestEntity} and return
	 * the response as {@link ResponseEntity}. Typically used in combination
	 * with the static builder methods on {@code RequestEntity}, for instance:
	 * <pre class="code">
	 * MyRequest body = ...
	 * RequestEntity request = RequestEntity.post(new URI(&quot;https://example.com/foo&quot;)).accept(MediaType.APPLICATION_JSON).body(body);
	 * ResponseEntity&lt;MyResponse&gt; response = template.exchange(request, MyResponse.class);
	 * </pre>
	 * @param requestEntity the entity to write to the request
	 * @param responseType the type of the return value
	 * @return the response as entity
	 * @since 4.1
	 */
	<T> ResponseEntity<T> exchange(RequestEntity<?> requestEntity, Class<T> responseType) throws RestClientException;

	/**
	 * Execute the request specified in the given {@link RequestEntity} and return
	 * the response as {@link ResponseEntity}. The given
	 * {@link ParameterizedTypeReference} is used to pass generic type information:
	 * <pre class="code">
	 * MyRequest body = ...
	 * RequestEntity request = RequestEntity.post(new URI(&quot;https://example.com/foo&quot;)).accept(MediaType.APPLICATION_JSON).body(body);
	 * ParameterizedTypeReference&lt;List&lt;MyResponse&gt;&gt; myBean = new ParameterizedTypeReference&lt;List&lt;MyResponse&gt;&gt;() {};
	 * ResponseEntity&lt;List&lt;MyResponse&gt;&gt; response = template.exchange(request, myBean);
	 * </pre>
	 * @param requestEntity the entity to write to the request
	 * @param responseType the type of the return value
	 * @return the response as entity
	 * @since 4.1
	 */
	<T> ResponseEntity<T> exchange(RequestEntity<?> requestEntity, ParameterizedTypeReference<T> responseType)
			throws RestClientException;


	// general execution

	/**
	 * Execute the HTTP method to the given URI template, preparing the request with the
	 * {@link RequestCallback}, and reading the response with a {@link ResponseExtractor}.
	 * <p>URI Template variables are expanded using the given URI variables, if any.
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestCallback object that prepares the request
	 * @param responseExtractor object that extracts the return value from the response
	 * @param uriVariables the variables to expand in the template
	 * @return an arbitrary object, as returned by the {@link ResponseExtractor}
	 */
	<T> T execute(String url, HttpMethod method, RequestCallback requestCallback,
			ResponseExtractor<T> responseExtractor, Object... uriVariables) throws RestClientException;

	/**
	 * Execute the HTTP method to the given URI template, preparing the request with the
	 * {@link RequestCallback}, and reading the response with a {@link ResponseExtractor}.
	 * <p>URI Template variables are expanded using the given URI variables map.
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestCallback object that prepares the request
	 * @param responseExtractor object that extracts the return value from the response
	 * @param uriVariables the variables to expand in the template
	 * @return an arbitrary object, as returned by the {@link ResponseExtractor}
	 */
	<T> T execute(String url, HttpMethod method, RequestCallback requestCallback,
			ResponseExtractor<T> responseExtractor, Map<String, ?> uriVariables) throws RestClientException;

	/**
	 * Execute the HTTP method to the given URL, preparing the request with the
	 * {@link RequestCallback}, and reading the response with a {@link ResponseExtractor}.
	 * @param url the URL
	 * @param method the HTTP method (GET, POST, etc)
	 * @param requestCallback object that prepares the request
	 * @param responseExtractor object that extracts the return value from the response
	 * @return an arbitrary object, as returned by the {@link ResponseExtractor}
	 */
	<T> T execute(URI url, HttpMethod method, RequestCallback requestCallback,
			ResponseExtractor<T> responseExtractor) throws RestClientException;

}
