feature: Add gateway pattern (#1297) (#2734)

* Implement Gateway pattern * Fixed docstrings * Fixed README.md * Fixed App * Fixed pom.xml * Fixed pom.xml * Fixed pom.xml * Fixed pom.xml * fixed checkstyle errors and directory names * fixed pom.xml * fixed checkstyle errors * Bug fixed * Bug fixed * Bug fixed * Bug fixed and code improvement * Bug fixed and code improvement * Bug fixed and update README.md * update APP.java * update gateway pattern * Revert "update gateway pattern" This reverts commit f31a00c268889b2c6b7690e07847df7247725999. * update gateway pattern --------- Co-authored-by: Finn <u7552286@anu.edu.au>
2026-08-22 08:23:59 +00:00 · 2024-03-10 10:55:18 +02:00
parent ec80239e5e
commit 2d54709d1a
12 changed files with 642 additions and 0 deletions
@@ -0,0 +1,68 @@
+/*
+ * 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.gateway;
+
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * the Gateway design pattern is a structural design pattern that provides a unified interface to a set of
+ * interfaces in a subsystem. It involves creating a Gateway interface that serves as a common entry point for
+ * interacting with various services, and concrete implementations of this interface for different external services.
+ *
+ * <p>In this example, GateFactory is the factory class, and it provides a method to create different kinds of external
+ * services. ExternalServiceA, B, and C are virtual implementations of the external services. Each service provides its
+ * own implementation of the execute() method. The Gateway interface is the common interface for all external services.
+ * The App class serves as the main entry point for the application implementing the Gateway design pattern. Through
+ * the Gateway interface, the App class could call each service with much less complexity.
+ */
+@Slf4j
+public class App {
+  /**
+   * Simulate an application calling external services.
+   */
+  public static void main(String[] args) throws Exception {
+    GatewayFactory gatewayFactory = new GatewayFactory();
+
+    // Register different gateways
+    gatewayFactory.registerGateway("ServiceA", new ExternalServiceA());
+    gatewayFactory.registerGateway("ServiceB", new ExternalServiceB());
+    gatewayFactory.registerGateway("ServiceC", new ExternalServiceC());
+
+    // Use an executor service for execution
+    Gateway serviceA = gatewayFactory.getGateway("ServiceA");
+    Gateway serviceB = gatewayFactory.getGateway("ServiceB");
+    Gateway serviceC = gatewayFactory.getGateway("ServiceC");
+
+    // Execute external services
+    try {
+      serviceA.execute();
+      serviceB.execute();
+      serviceC.execute();
+    } catch (ThreadDeath e) {
+      LOGGER.info("Interrupted!" + e);
+      throw e;
+    }
+  }
+}
@@ -0,0 +1,43 @@
+/*
+ * 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.gateway;
+
+
+import lombok.extern.slf4j.Slf4j;
+import org.slf4j.Logger;
+
+/**
+* ExternalServiceA is one of external services.
+*/
+@Slf4j
+class ExternalServiceA implements Gateway {
+  @Override
+  public void execute() throws Exception {
+    LOGGER.info("Executing Service A");
+    // Simulate a time-consuming task
+    Thread.sleep(1000);
+  }
+}
+
@@ -0,0 +1,42 @@
+/*
+ * 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.gateway;
+
+
+import lombok.extern.slf4j.Slf4j;
+
+/**
+* ExternalServiceB is one of external services.
+*/
+@Slf4j
+class ExternalServiceB implements Gateway {
+  @Override
+  public void execute() throws Exception {
+    LOGGER.info("Executing Service B");
+    // Simulate a time-consuming task
+    Thread.sleep(1000);
+  }
+}
+
@@ -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.gateway;
+
+
+import lombok.extern.slf4j.Slf4j;
+
+/**
+* ExternalServiceC is one of external services.
+*/
+@Slf4j
+class ExternalServiceC implements Gateway {
+  @Override
+  public void execute() throws Exception {
+    LOGGER.info("Executing Service C");
+    // Simulate a time-consuming task
+    Thread.sleep(1000);
+  }
+
+  public void error() throws Exception {
+    // Simulate an exception
+    throw new RuntimeException("Service C encountered an error");
+  }
+}
@@ -0,0 +1,8 @@
+package com.iluwatar.gateway;
+
+/**
+ * Service interface.
+ */
+interface Gateway {
+  void execute() throws Exception;
+}
@@ -0,0 +1,20 @@
+package com.iluwatar.gateway;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * The "GatewayFactory" class is responsible for providing different external services in this Gateway design pattern
+ * example. It allows clients to register and retrieve specific gateways based on unique keys.
+ */
+public class GatewayFactory {
+  private Map<String, Gateway> gateways = new HashMap<>();
+
+  public void registerGateway(String key, Gateway gateway) {
+    gateways.put(key, gateway);
+  }
+
+  public Gateway getGateway(String key) {
+    return gateways.get(key);
+  }
+}
@@ -0,0 +1,85 @@
+package com.iluwatar.gateway;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class AppTest {
+    private GatewayFactory gatewayFactory;
+    private ExecutorService executorService;
+
+    @Before
+    public void setUp() {
+        gatewayFactory = new GatewayFactory();
+        executorService = Executors.newFixedThreadPool(2);
+        gatewayFactory.registerGateway("ServiceA", new ExternalServiceA());
+        gatewayFactory.registerGateway("ServiceB", new ExternalServiceB());
+        gatewayFactory.registerGateway("ServiceC", new ExternalServiceC());
+    }
+
+    @Test
+    public void testServiceAExecution() throws InterruptedException, ExecutionException {
+        // Test Service A execution
+        Future<?> serviceAFuture = executorService.submit(() -> {
+            try {
+                Gateway serviceA = gatewayFactory.getGateway("ServiceA");
+                serviceA.execute();
+            } catch (Exception e) {
+                fail("Service A should not throw an exception.");
+            }
+        });
+
+        // Wait for Service A to complete
+        serviceAFuture.get();
+    }
+
+    @Test
+    public void testServiceCExecutionWithException() throws InterruptedException, ExecutionException {
+        // Test Service B execution with an exception
+        Future<?> serviceBFuture = executorService.submit(() -> {
+            try {
+                Gateway serviceB = gatewayFactory.getGateway("ServiceB");
+                serviceB.execute();
+            } catch (Exception e) {
+                fail("Service B should not throw an exception.");
+            }
+        });
+
+        // Wait for Service B to complete
+        serviceBFuture.get();
+    }
+
+    @Test
+    public void testServiceCExecution() throws InterruptedException, ExecutionException {
+        // Test Service C execution
+        Future<?> serviceCFuture = executorService.submit(() -> {
+            try {
+                Gateway serviceC = gatewayFactory.getGateway("ServiceC");
+                serviceC.execute();
+            } catch (Exception e) {
+                fail("Service C should not throw an exception.");
+            }
+        });
+
+        // Wait for Service C to complete
+        serviceCFuture.get();
+    }
+
+    @Test
+    public void testServiceCError() {
+        try {
+            ExternalServiceC serviceC = (ExternalServiceC) gatewayFactory.getGateway("ServiceC");
+            serviceC.error();
+            fail("Service C should throw an exception.");
+        } catch (Exception e) {
+            assertEquals("Service C encountered an error", e.getMessage());
+        }
+    }
+}
@@ -0,0 +1,69 @@
+package com.iluwatar.gateway;
+
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class ServiceFactoryTest {
+    private GatewayFactory gatewayFactory;
+    private ExecutorService executorService;
+
+    @Before
+    public void setUp() {
+        gatewayFactory = new GatewayFactory();
+        executorService = Executors.newFixedThreadPool(2);
+        gatewayFactory.registerGateway("ServiceA", new ExternalServiceA());
+        gatewayFactory.registerGateway("ServiceB", new ExternalServiceB());
+        gatewayFactory.registerGateway("ServiceC", new ExternalServiceC());
+    }
+
+    @Test
+    public void testGatewayFactoryRegistrationAndRetrieval() {
+        Gateway serviceA = gatewayFactory.getGateway("ServiceA");
+        Gateway serviceB = gatewayFactory.getGateway("ServiceB");
+        Gateway serviceC = gatewayFactory.getGateway("ServiceC");
+
+        // Check if the retrieved instances match their expected types
+        assertTrue("ServiceA should be an instance of ExternalServiceA", serviceA instanceof ExternalServiceA);
+        assertTrue("ServiceB should be an instance of ExternalServiceB", serviceB instanceof ExternalServiceB);
+        assertTrue("ServiceC should be an instance of ExternalServiceC", serviceC instanceof ExternalServiceC);
+    }
+
+    @Test
+    public void testGatewayFactoryRegistrationWithNonExistingKey() {
+        Gateway nonExistingService = gatewayFactory.getGateway("NonExistingService");
+        assertEquals(null, nonExistingService);
+    }
+
+    @Test
+    public void testGatewayFactoryConcurrency() throws InterruptedException {
+        int numThreads = 10;
+        CountDownLatch latch = new CountDownLatch(numThreads);
+        AtomicBoolean failed = new AtomicBoolean(false);
+
+        for (int i = 0; i < numThreads; i++) {
+            executorService.submit(() -> {
+                try {
+                    Gateway serviceA = gatewayFactory.getGateway("ServiceA");
+                    serviceA.execute();
+                } catch (Exception e) {
+                    failed.set(true);
+                } finally {
+                    latch.countDown();
+                }
+            });
+        }
+
+        latch.await();
+        assertTrue("This should not fail", !failed.get());
+    }
+}