Adding appropriate comments on classes and full description in App.java. Removing added function in ServiceAmbassador as it's not appropriate for the example.
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@ -1,5 +1,44 @@
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/**
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* The MIT License
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* Copyright (c) 2014-2016 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.ambassador;
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/**
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*
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* The ambassador pattern creates a helper service that sends network requests on behalf of a
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* client. It is often used in cloud-based applications to offload features of a remote service.
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*
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* An ambassador service can be thought of as an out-of-process proxy that is co-located with
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* the client. Similar to the proxy design pattern, the ambassador service provides an interface
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* for another remote service. In addition to the interface, the ambassador provides extra
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* functionality and features, specifically offloaded common connectivity tasks. This usually
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* consists of monitoring, logging, routing, security etc. This is extremely useful in
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* legacy applications where the codebase is difficult to modify and allows for improvements
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* in the application's networking capabilities.
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*
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* In this example, we will the ({@link ServiceAmbassador}) class represents the ambassador while the
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* ({@link RemoteService}) class represents a remote application.
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*
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*/
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public class App {
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/**
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@ -9,11 +48,7 @@ public class App {
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Client host1 = new Client();
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Client host2 = new Client();
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host1.useService(12);
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host2.useService(73);
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host1.useNewService(12);
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host2.useNewService(73);
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}
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}
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@ -22,6 +22,9 @@
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*/
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package com.iluwatar.ambassador;
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/**
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* A simple Client
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*/
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public class Client {
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private ServiceAmbassador serviceAmbassador;
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@ -34,9 +37,4 @@ public class Client {
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long result = serviceAmbassador.doRemoteFunction(value);
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System.out.println(result);
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}
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void useNewService(int value) {
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long result = serviceAmbassador.doAddedFunction(value);
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System.out.println(result);
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}
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}
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@ -24,6 +24,9 @@ package com.iluwatar.ambassador;
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import static java.lang.Thread.sleep;
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/**
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* A remote legacy application represented by a Singleton implementation.
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*/
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public class RemoteService implements RemoteServiceInterface {
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private static RemoteService service = null;
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@ -39,6 +42,12 @@ public class RemoteService implements RemoteServiceInterface {
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}
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/**
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* Remote function takes a value and multiplies it by 10 taking a random amount of time.
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* Will sometimes return -1. This immitates connectivity issues a client might have to account for.
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* @param value integer value to be multiplied.
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* @return if waitTime is more than 200ms, it returns value * 10, otherwise -1.
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*/
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@Override
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public long doRemoteFunction(int value) {
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@ -22,6 +22,9 @@
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*/
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package com.iluwatar.ambassador;
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/**
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* Interface shared by ({@link RemoteService}) and ({@link ServiceAmbassador}).
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*/
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interface RemoteServiceInterface {
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long doRemoteFunction(int value) throws Exception;
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@ -27,6 +27,13 @@ import org.slf4j.LoggerFactory;
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import static java.lang.Thread.sleep;
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/**
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*
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* ServiceAmbassador provides an interface for a ({@link Client}) to access ({@link RemoteService}).
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* The interface adds logging, latency testing and usage of the service in a safe way that will not
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* add stress to the remote service when connectivity issues occur.
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*
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*/
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public class ServiceAmbassador implements RemoteServiceInterface {
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private static final Logger LOGGER = LoggerFactory.getLogger(ServiceAmbassador.class);
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@ -43,10 +50,6 @@ public class ServiceAmbassador implements RemoteServiceInterface {
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return safeCall(value);
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}
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long doAddedFunction(int value) {
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return safeCall(value) * 5;
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}
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private long checkLatency(int value) {
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RemoteService service = RemoteService.getRemoteService();
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long startTime = System.currentTimeMillis();
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