feature: #2542 Dynamic proxy pattern (#2814)

* #2542 First commit * #2542 Fixing comments * #2542 Refactoring code * #2542 Update Readme * #2542 Add mockito dependencies * #2542 Add unit test * #2542 Fixes for testing * #2542 Fixing typos * #2542 Fixing SonarLint issues * #2542 Fixing code review --------- Co-authored-by: Sashir Estela <sashirestela@yahoo.com> Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>
2026-05-15 00:58:24 +00:00 · 2024-03-23 05:34:32 -05:00
parent 4b704c807f
commit f65bb820d8
22 changed files with 1542 additions and 0 deletions
@@ -0,0 +1,46 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+/**
+ * This class represents an endpoint resource that
+ * we are going to interchange with a Rest API server.
+ */
+@Data
+@AllArgsConstructor
+@NoArgsConstructor(force = true)
+@Builder
+public class Album {
+
+  private Integer id;
+  private String title;
+  private Integer userId;
+
+}
@@ -0,0 +1,61 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy;
+
+import com.iluwatar.dynamicproxy.tinyrestclient.TinyRestClient;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.net.http.HttpClient;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Class whose method 'invoke' will be called every time that an interface's method is called.
+ * That interface is linked to this class by the Proxy class.
+ */
+@Slf4j
+public class AlbumInvocationHandler implements InvocationHandler {
+
+  private TinyRestClient restClient;
+
+  /**
+   * Class constructor. It instantiates a TinyRestClient object.
+   *
+   * @param baseUrl    Root url for endpoints.
+   * @param httpClient Handle the http communication.
+   */
+  public AlbumInvocationHandler(String baseUrl, HttpClient httpClient) {
+    this.restClient = new TinyRestClient(baseUrl, httpClient);
+  }
+
+  @Override
+  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+
+    LOGGER.info("===== Calling the method {}.{}()",
+        method.getDeclaringClass().getSimpleName(), method.getName());
+
+    return restClient.send(method, args);
+  }
+
+}
@@ -0,0 +1,87 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy;
+
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Body;
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Delete;
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Get;
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Path;
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Post;
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Put;
+import java.util.List;
+
+/**
+ * Every method in this interface is annotated with the necessary metadata to represents an endpoint
+ * that we can call to communicate with a host server which is serving a resource by Rest API.
+ * This interface is focused in the resource Album.
+ */
+public interface AlbumService {
+
+  /**
+   * Get a list of albums from an endpoint.
+   *
+   * @return List of albums' data.
+   */
+  @Get("/albums")
+  List<Album> readAlbums();
+
+  /**
+   * Get a specific album from an endpoint.
+   *
+   * @param albumId Album's id to search for.
+   * @return Album's data.
+   */
+  @Get("/albums/{albumId}")
+  Album readAlbum(@Path("albumId") Integer albumId);
+
+  /**
+   * Creates a new album.
+   *
+   * @param album Album's data to be created.
+   * @return New album's data.
+   */
+  @Post("/albums")
+  Album createAlbum(@Body Album album);
+
+  /**
+   * Updates an existing album.
+   *
+   * @param albumId Album's id to be modified.
+   * @param album   New album's data.
+   * @return Updated album's data.
+   */
+  @Put("/albums/{albumId}")
+  Album updateAlbum(@Path("albumId") Integer albumId, @Body Album album);
+
+  /**
+   * Deletes an album.
+   *
+   * @param albumId Album's id to be deleted.
+   * @return Empty album.
+   */
+  @Delete("/albums/{albumId}")
+  Album deleteAlbum(@Path("albumId") Integer albumId);
+
+}
@@ -0,0 +1,109 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy;
+
+import java.lang.reflect.Proxy;
+import java.net.http.HttpClient;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Application to demonstrate the Dynamic Proxy pattern. This application allow us to hit the public
+ * fake API https://jsonplaceholder.typicode.com for the resource Album through an interface.
+ * The call to Proxy.newProxyInstance creates a new dynamic proxy for the AlbumService interface and
+ * sets the AlbumInvocationHandler class as the handler to intercept all the interface's methods.
+ * Everytime that we call an AlbumService's method, the handler's method "invoke" will be call
+ * automatically, and it will pass all the method's metadata and arguments to other specialized
+ * class - TinyRestClient - to prepare the Rest API call accordingly.
+ * In this demo, the Dynamic Proxy pattern help us to run business logic through interfaces without
+ * an explicit implementation of the interfaces and supported on the Java Reflection approach.
+ */
+@Slf4j
+public class App {
+
+  static final String REST_API_URL = "https://jsonplaceholder.typicode.com";
+
+  private String baseUrl;
+  private HttpClient httpClient;
+  private AlbumService albumServiceProxy;
+
+  /**
+   * Class constructor.
+   *
+   * @param baseUrl    Root url for endpoints.
+   * @param httpClient Handle the http communication.
+   */
+  public App(String baseUrl, HttpClient httpClient) {
+    this.baseUrl = baseUrl;
+    this.httpClient = httpClient;
+  }
+
+  /**
+   * Application entry point.
+   *
+   * @param args External arguments to be passed. Optional.
+   */
+  public static void main(String[] args) {
+    App app = new App(App.REST_API_URL, HttpClient.newHttpClient());
+    app.createDynamicProxy();
+    app.callMethods();
+  }
+
+  /**
+   * Create the Dynamic Proxy linked to the AlbumService interface and to the AlbumInvocationHandler.
+   */
+  public void createDynamicProxy() {
+    AlbumInvocationHandler albumInvocationHandler = new AlbumInvocationHandler(baseUrl, httpClient);
+
+    albumServiceProxy = (AlbumService) Proxy.newProxyInstance(
+        App.class.getClassLoader(), new Class<?>[]{AlbumService.class}, albumInvocationHandler);
+  }
+
+  /**
+   * Call the methods of the Dynamic Proxy, in other words, the AlbumService interface's methods
+   * and receive the responses from the Rest API.
+   */
+  public void callMethods() {
+    int albumId = 17;
+    int userId = 3;
+
+    var albums = albumServiceProxy.readAlbums();
+    albums.forEach(album -> LOGGER.info("{}", album));
+
+    var album = albumServiceProxy.readAlbum(albumId);
+    LOGGER.info("{}", album);
+
+    var newAlbum = albumServiceProxy.createAlbum(Album.builder()
+        .title("Big World").userId(userId).build());
+    LOGGER.info("{}", newAlbum);
+
+    var editAlbum = albumServiceProxy.updateAlbum(albumId, Album.builder()
+        .title("Green Valley").userId(userId).build());
+    LOGGER.info("{}", editAlbum);
+
+    var removedAlbum = albumServiceProxy.deleteAlbum(albumId);
+    LOGGER.info("{}", removedAlbum);
+  }
+
+}
@@ -0,0 +1,98 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.type.CollectionType;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * Utility class to handle Json operations.
+ */
+@Slf4j
+public class JsonUtil {
+
+  private static ObjectMapper objectMapper = new ObjectMapper();
+
+  private JsonUtil() {
+  }
+
+  /**
+   * Convert an object to a Json string representation.
+   *
+   * @param object Object to convert.
+   * @param <T>    Object's class.
+   * @return Json string.
+   */
+  public static <T> String objectToJson(T object) {
+    try {
+      return objectMapper.writeValueAsString(object);
+    } catch (JsonProcessingException e) {
+      LOGGER.error("Cannot convert the object " + object + " to Json.", e);
+      return null;
+    }
+  }
+
+  /**
+   * Convert a Json string to an object of a class.
+   *
+   * @param json  Json string to convert.
+   * @param clazz Object's class.
+   * @param <T>   Object's generic class.
+   * @return Object.
+   */
+  public static <T> T jsonToObject(String json, Class<T> clazz) {
+    try {
+      return objectMapper.readValue(json, clazz);
+    } catch (IOException e) {
+      LOGGER.error("Cannot convert the Json " + json + " to class " + clazz.getName() + ".", e);
+      return null;
+    }
+  }
+
+  /**
+   * Convert a Json string to a List of objects of a class.
+   *
+   * @param json  Json string to convert.
+   * @param clazz Object's class.
+   * @param <T>   Object's generic class.
+   * @return List of objects.
+   */
+  public static <T> List<T> jsonToList(String json, Class<T> clazz) {
+    try {
+      CollectionType listType = objectMapper.getTypeFactory()
+          .constructCollectionType(ArrayList.class, clazz);
+      return objectMapper.reader().forType(listType).readValue(json);
+    } catch (JsonProcessingException e) {
+      LOGGER.error("Cannot convert the Json " + json + " to List of " + clazz.getName() + ".", e);
+      return List.of();
+    }
+  }
+
+}
@@ -0,0 +1,182 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient;
+
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Body;
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Http;
+import com.iluwatar.dynamicproxy.tinyrestclient.annotation.Path;
+import java.io.IOException;
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.net.HttpURLConnection;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.web.util.UriUtils;
+
+/**
+ * Class to handle all the http communication with a Rest API.
+ * It is supported by the HttpClient Java library.
+ */
+@Slf4j
+public class TinyRestClient {
+
+  private static Map<Method, Annotation> httpAnnotationByMethod = new HashMap<>();
+
+  private String baseUrl;
+  private HttpClient httpClient;
+
+  /**
+   * Class constructor.
+   *
+   * @param baseUrl    Root url for endpoints.
+   * @param httpClient Handle the http communication.
+   */
+  public TinyRestClient(String baseUrl, HttpClient httpClient) {
+    this.baseUrl = baseUrl;
+    this.httpClient = httpClient;
+  }
+
+  /**
+   * Creates a http communication to request and receive data from an endpoint.
+   *
+   * @param method Interface's method which is annotated with a http method.
+   * @param args   Method's arguments passed in the call.
+   * @return Response from the endpoint.
+   * @throws IOException          Exception thrown when any fail happens in the call.
+   * @throws InterruptedException Exception thrown when call is interrupted.
+   */
+  public Object send(Method method, Object[] args) throws IOException, InterruptedException {
+    var httpAnnotation = getHttpAnnotation(method);
+    if (httpAnnotation == null) {
+      return null;
+    }
+    var httpAnnotationName = httpAnnotation.annotationType().getSimpleName().toUpperCase();
+    var url = baseUrl + buildUrl(method, args, httpAnnotation);
+    var bodyPublisher = buildBodyPublisher(method, args);
+    var httpRequest = HttpRequest.newBuilder()
+        .uri(URI.create(url))
+        .header("Content-Type", "application/json")
+        .method(httpAnnotationName, bodyPublisher)
+        .build();
+    var httpResponse = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofString());
+    var statusCode = httpResponse.statusCode();
+    if (statusCode >= HttpURLConnection.HTTP_BAD_REQUEST) {
+      var errorDetail = httpResponse.body();
+      LOGGER.error("Error from server: " + errorDetail);
+      return null;
+    }
+    return getResponse(method, httpResponse);
+  }
+
+  private String buildUrl(Method method, Object[] args, Annotation httpMethodAnnotation) {
+    var url = annotationValue(httpMethodAnnotation);
+    if (url == null) {
+      return "";
+    }
+    var index = 0;
+    for (var parameter : method.getParameters()) {
+      var pathAnnotation = getAnnotationOf(parameter.getDeclaredAnnotations(), Path.class);
+      if (pathAnnotation != null) {
+        var pathParam = "{" + annotationValue(pathAnnotation) + "}";
+        var pathValue = UriUtils.encodePath(args[index].toString(), StandardCharsets.UTF_8);
+        url = url.replace(pathParam, pathValue);
+      }
+      index++;
+    }
+    return url;
+  }
+
+  private HttpRequest.BodyPublisher buildBodyPublisher(Method method, Object[] args) {
+    var index = 0;
+    for (var parameter : method.getParameters()) {
+      var bodyAnnotation = getAnnotationOf(parameter.getDeclaredAnnotations(), Body.class);
+      if (bodyAnnotation != null) {
+        var body = JsonUtil.objectToJson(args[index]);
+        return HttpRequest.BodyPublishers.ofString(body);
+      }
+      index++;
+    }
+    return HttpRequest.BodyPublishers.noBody();
+  }
+
+  private Object getResponse(Method method, HttpResponse<String> httpResponse) {
+    var rawData = httpResponse.body();
+    Type returnType = null;
+    try {
+      returnType = method.getGenericReturnType();
+    } catch (Exception e) {
+      LOGGER.error("Cannot get the generic return type of the method " + method.getName() + "()");
+      return null;
+    }
+    if (returnType instanceof ParameterizedType) {
+      Class<?> responseClass = (Class<?>) (((ParameterizedType) returnType)
+          .getActualTypeArguments()[0]);
+      return JsonUtil.jsonToList(rawData, responseClass);
+    } else {
+      Class<?> responseClass = method.getReturnType();
+      return JsonUtil.jsonToObject(rawData, responseClass);
+    }
+  }
+
+  private Annotation getHttpAnnotation(Method method) {
+    return httpAnnotationByMethod.computeIfAbsent(method, m ->
+        Arrays.stream(m.getDeclaredAnnotations())
+            .filter(annot -> annot.annotationType().isAnnotationPresent(Http.class))
+            .findFirst().orElse(null));
+  }
+
+  private Annotation getAnnotationOf(Annotation[] annotations, Class<?> clazz) {
+    return Arrays.stream(annotations)
+        .filter(annot -> annot.annotationType().equals(clazz))
+        .findFirst().orElse(null);
+  }
+
+  private String annotationValue(Annotation annotation) {
+    var valueMethod = Arrays.stream(annotation.annotationType().getDeclaredMethods())
+        .filter(methodAnnot -> methodAnnot.getName().equals("value"))
+        .findFirst().orElse(null);
+    if (valueMethod == null) {
+      return null;
+    }
+    Object result;
+    try {
+      result = valueMethod.invoke(annotation, (Object[]) null);
+    } catch (Exception e) {
+      LOGGER.error("Cannot read the value " + annotation.annotationType().getSimpleName()
+          + "." + valueMethod.getName() + "()", e);
+      result = null;
+    }
+    return (result instanceof String strResult ? strResult : null);
+  }
+}
@@ -0,0 +1,39 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark a method's parameter as a Body parameter.
+ * It is typically used on Post and Put http methods.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.PARAMETER)
+public @interface Body {
+}
@@ -0,0 +1,45 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark an interface's method as a DELETE http method.
+ */
+@Http
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Delete {
+  /**
+   * Set the url for this http method.
+   *
+   * @return Url address.
+   */
+  String value() default "";
+}
@@ -0,0 +1,45 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark an interface's method as a GET http method.
+ */
+@Http
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Get {
+  /**
+   * Set the url for this http method.
+   *
+   * @return Url address.
+   */
+  String value() default "";
+}
@@ -0,0 +1,38 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark other annotations to be recognized as http methods.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.ANNOTATION_TYPE)
+public @interface Http {
+}
@@ -0,0 +1,44 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark a method's parameter as a Path parameter.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.PARAMETER)
+public @interface Path {
+  /**
+   * Path parameter to be replaced in the url.
+   *
+   * @return Path parameter.
+   */
+  String value();
+}
@@ -0,0 +1,45 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark an interface's method as a POST http method.
+ */
+@Http
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Post {
+  /**
+   * Set the url for this http method.
+   *
+   * @return Url address.
+   */
+  String value() default "";
+}
@@ -0,0 +1,45 @@
+/*
+ * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.dynamicproxy.tinyrestclient.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark an interface's method as a PUT http method.
+ */
+@Http
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Put {
+  /**
+   * Set the url for this http method.
+   *
+   * @return Url address.
+   */
+  String value() default "";
+}