Connection.java

/**
 * Created by sameerraghuram on 4/22/17.
 */

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

import java.io.IOException;
import java.util.concurrent.Callable;
import java.util.function.Consumer;

/**
 * TODO: Write a relaible function to send JSON messages
 * TODO: Write a Server (Done)
 * TODO: Figure out how GSON works
 */

public class Connection {

 String broker;
 ClientListener clientListener;
 Callbacks callbacks;

 public Connection(String broker){
 this.broker = broker;
 clientListener = new ClientListener();
 callbacks = Callbacks.getInstance();
 Thread listener = new Thread(clientListener);
 listener.start();

 }

 /**
 * Sends a request to the Broker to subscribe the client
 * to a message queue residing on the default exchange.
 *
 * @param queueName: ID of the message queue on the broker
 * @param callback: Function to be called everytime a new message arrives.
 */
 public void subscribe(String queueName, Consumer<String> callback){
 // Construct the request here

 // Step 1: Make the GSON object
 Gson gson = new GsonBuilder().setPrettyPrinting().create();

 // Step 2: Create the request JSON string
 SubscribeMessage subscribeMessage = new SubscribeMessage(queueName);
 String message = gson.toJson(subscribeMessage);

 // Step 3: Register callback to queue-id
 this.callbacks.put(queueName, callback);

 // Step 4: Send message
 try {
 Messenger messenger = new Messenger(this.broker, 12344);
 messenger.sendMessage(message);
 } catch (IOException e) {
 e.printStackTrace();
 }

 }

 /**
 * Sends a request to the Broker to subscribe the client
 * to a message queue residing on the exchange given by exchangeName.
 *
 * @param exchangeName: Identity of the exchange
 * @param queueName: ID of the message queue on the broker
 * @param callback: Function to be called everytime a new message arrives.
 */
 public void subscribe(String exchangeName, String queueName, Consumer<String> callback){
 // Step 1: Make the GSON object
 Gson gson = new GsonBuilder().setPrettyPrinting().create();

 // Step 2: Create the request JSON string
 SubscribeMessage subscribeMessage = new SubscribeMessage(exchangeName, queueName);
 String message = gson.toJson(subscribeMessage);

 // Step 3: Register callback to queue-id
 this.callbacks.put(exchangeName + "." + queueName, callback);

 // TODO: Step 4: Send message
 try {
 Messenger messenger = new Messenger(this.broker, 12344);
 messenger.sendMessage(message);
 } catch (IOException e) {
 e.printStackTrace();
 }

 }

 public void createQueue(String exchangeName, String queueName){
 // Step 1: Make the GSON object
 Gson gson = new GsonBuilder().setPrettyPrinting().create();

 // Step 2: Create the request JSON string
 CreateQueueMessage createQueueMessage = new CreateQueueMessage(exchangeName, queueName);
 String message = gson.toJson(createQueueMessage);

 // Step 3: Send message
 try {
 Messenger messenger = new Messenger(this.broker, 12344);
 messenger.sendMessage(message);
 } catch (IOException e) {
 e.printStackTrace();
 }
 }

 public void createQueue(String queueName){
 // Step 1: Make the GSON object
 Gson gson = new GsonBuilder().setPrettyPrinting().create();

 // Step 2: Create the request JSON string
 CreateQueueMessage createQueueMessage = new CreateQueueMessage(queueName);
 String message = gson.toJson(createQueueMessage);

 // Step 3: Send message
 try {
 Messenger messenger = new Messenger(this.broker, 12344);
 messenger.sendMessage(message);
 //System.out.println(message);
 } catch (Exception e) {
 e.printStackTrace();
 }
 }

 public void publish(String queueName, String message){
 // Step 1: Make the GSON object
 Gson gson = new GsonBuilder().setPrettyPrinting().create();

 // Step 2: Create the request JSON string
 PublishMessage publishMessage = new PublishMessage(queueName, message);
 message = gson.toJson(publishMessage);

 // TODO: Step 4: Send message
 try {
 Messenger messenger = new Messenger(this.broker, 12344);
 messenger.sendMessage(message);
 } catch (IOException e) {
 e.printStackTrace();
 }
 }

}