Ambassador adds logging, imitates trying to connect to remote service and provides new client-side functionality. Need to clean up code, add tests and add descriptive comments.

ambassador/pom.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>java-design-patterns</artifactId>
+        <groupId>com.iluwatar</groupId>
+        <version>1.20.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>ambassador</artifactId>
+
+
+</project>

ambassador/src/main/java/com/iluwatar/ambassador/App.java

@@ -0,0 +1,19 @@
+package com.iluwatar.ambassador;
+
+public class App {
+
+    /**
+     * Entry point
+     */
+    public static void main(String[] args) {
+
+        Client host1 = new Client();
+        Client host2 = new Client();
+
+        host1.useService(12);
+        host2.useService(73);
+
+        host1.useNewService(12);
+        host2.useNewService(73);
+    }
+}

ambassador/src/main/java/com/iluwatar/ambassador/Client.java

@@ -0,0 +1,42 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 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.ambassador;
+
+public class Client {
+
+    private ServiceAmbassador serviceAmbassador;
+
+    Client() {
+        serviceAmbassador = new ServiceAmbassador();
+    }
+
+    void useService(int value) {
+        long result = serviceAmbassador.doRemoteFunction(value);
+        System.out.println(result);
+    }
+
+    void useNewService(int value) {
+        long result = serviceAmbassador.doAddedFunction(value);
+        System.out.println(result);
+    }
+}

ambassador/src/main/java/com/iluwatar/ambassador/RemoteService.java

@@ -0,0 +1,54 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 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.ambassador;
+
+import static java.lang.Thread.sleep;
+
+public class RemoteService implements RemoteServiceInterface {
+
+    private static RemoteService service = null;
+
+    static synchronized RemoteService getRemoteService() {
+        if (service == null) {
+            service = new RemoteService();
+        }
+        return service;
+    }
+
+    private RemoteService() {
+
+    }
+
+    @Override
+    public long doRemoteFunction(int value) {
+
+        long waitTime = (long) Math.floor(Math.random() * 1000);
+
+        try {
+            sleep(waitTime);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        return waitTime >= 200 ? value * 10 : -1;
+    }
+}

ambassador/src/main/java/com/iluwatar/ambassador/RemoteServiceInterface.java

@@ -0,0 +1,28 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 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.ambassador;
+
+interface RemoteServiceInterface {
+
+    long doRemoteFunction(int value) throws Exception;
+}

ambassador/src/main/java/com/iluwatar/ambassador/ServiceAmbassador.java

@@ -0,0 +1,85 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 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.ambassador;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static java.lang.Thread.sleep;
+
+public class ServiceAmbassador implements RemoteServiceInterface {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(ServiceAmbassador.class);
+    private static final int RETRIES = 3;
+    private static final int DELAY_MS = 3000;
+
+    ServiceAmbassador() {
+
+    }
+
+    @Override
+    public long doRemoteFunction(int value) {
+
+        return safeCall(value);
+    }
+
+    long doAddedFunction(int value) {
+        return safeCall(value) * 5;
+    }
+
+    private long checkLatency(int value) {
+        RemoteService service = RemoteService.getRemoteService();
+        long startTime = System.currentTimeMillis();
+        long result = service.doRemoteFunction(value);
+        long timeTaken = System.currentTimeMillis() - startTime;
+
+        LOGGER.info("Time taken (ms): " + timeTaken);
+        return result;
+    }
+
+    private long safeCall(int value) {
+
+        int retries = 0;
+        long result = -1;
+
+        for (int i = 0; i < RETRIES; i++) {
+
+            if (retries >= RETRIES) {
+                return -1;
+            }
+
+            if ((result = checkLatency(value)) == -1) {
+                LOGGER.info("Failed to reach remote: (" + (i + 1) + ")");
+                retries++;
+                try {
+                    sleep(DELAY_MS);
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            } else {
+                break;
+            }
+        }
+        return result;
+    }
+}

pom.xml

@@ -161,6 +161,7 @@
         <module>dirty-flag</module>
         <module>trampoline</module>
         <module>serverless</module>
+        <module>ambassador</module>
     </modules>
 
     <repositories>