Message passing in RabbitMQ to seperate process successful

pom.xml

@@ -64,6 +64,12 @@
             <artifactId>slf4j-api</artifactId>
             <version>1.7.30</version>
         </dependency>
+        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-pool2 -->
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-pool2</artifactId>
+            <version>2.9.0</version>
+        </dependency>
     </dependencies>
 
 </project>

src/main/java/SkierServlet.java

@@ -1,3 +1,4 @@
+import com.rabbitmq.client.Channel;
 import com.rabbitmq.client.Connection;
 import com.rabbitmq.client.ConnectionFactory;
 import data.SkierDbConnection;
@@ -17,9 +18,13 @@
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.pool2.ObjectPool;
+import org.apache.commons.pool2.impl.GenericObjectPool;
 import org.json.JSONException;
 import org.json.JSONObject;
 import utils.JsonFormatter;
+import utils.RabbitMQChannelFactory;
 
 @WebServlet(name = "SkierServlet")
 public class SkierServlet extends HttpServlet {
@@ -28,12 +33,15 @@ public class SkierServlet extends HttpServlet {
     // RabbitMQ objects
     private final static String QUEUE_NAME = "DB_POST";
     private Connection rmqConn;
+    private ObjectPool<Channel> channelPool;
 
     /**
      * Used to set up RabbitMQ. Does not use the config object.
      */
     public void init(ServletConfig config) throws ServletException  {
         super.init(config);
+
+        // Connection setup
         ConnectionFactory factory = new ConnectionFactory();
         factory.setHost("localhost");
         try {
@@ -42,14 +50,25 @@ public void init(ServletConfig config) throws ServletException  {
             e.printStackTrace();
             throw new ServletException("couldn't connect to RabbitMQ");
         }
+
+        // Channel pool setup
+        channelPool= new GenericObjectPool<>(new RabbitMQChannelFactory(rmqConn));
     }
 
+    /**
+     * Cleans up RabbitMQ leftovers.
+     */
     public void destroy() {
         try {
             rmqConn.close();
         } catch (IOException e) {
             e.printStackTrace();
         }
+        try {
+            channelPool.clear();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
     }
 
     /**
@@ -93,15 +112,36 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
         int time = requestJson.getInt(keys[3]);
         int lift = requestJson.getInt(keys[4]);
 
-        // Write the response
+        // Do the request and write response
         PrintWriter out = response.getWriter();
         try {
+            // Get and declare a channel
+            Channel channel = channelPool.borrowObject();
+            //Channel channel = rmqConn.createChannel();
+            channel.queueDeclare(QUEUE_NAME, false, false, false, null);
+
+            // Keep the message as simple as possible, just the arguments.
+            // Consumers will know the schema here.
+            String message = String.format(
+                    "%s %d %d %d %d", resort, day, skier, time, lift);
+            // Send it
+            channel.basicPublish("", QUEUE_NAME, null, message.getBytes());
+            channelPool.returnObject(channel);
+
+            // TODO: Move db processing to consumer program
             dbConn.postLiftRide(resort, day, skier, time, lift);
+
+            // Send a successful response
             response.setStatus(HttpServletResponse.SC_CREATED);
         } catch (SQLException e) {
             response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
             out.println(JsonFormatter.buildError("problem executing SQL: "
                     + e.getMessage()));  // For development
+        } catch (Exception e) {
+            // Error with RabbitMQ
+            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
+            out.println(JsonFormatter.buildError("problem pushing to worker queue: "
+                    + e.getMessage()));  // For development
         }
     }
 

src/main/java/utils/RabbitMQChannelFactory.java

@@ -0,0 +1,31 @@
+package utils;
+
+import com.rabbitmq.client.Channel;
+import com.rabbitmq.client.Connection;
+import org.apache.commons.pool2.BasePooledObjectFactory;
+import org.apache.commons.pool2.PooledObject;
+import org.apache.commons.pool2.impl.DefaultPooledObject;
+
+/**
+ * Provides a connection pool for RabbitMQ channel objects.
+ */
+public class RabbitMQChannelFactory
+    extends BasePooledObjectFactory<Channel> {
+
+    private final Connection conn;
+
+    public RabbitMQChannelFactory(Connection conn) {
+        super();
+        this.conn = conn;
+    }
+
+    @Override
+    public Channel create() throws Exception {
+        return conn.createChannel();
+    }
+
+    @Override
+    public PooledObject<Channel> wrap(Channel channel) {
+        return new DefaultPooledObject<>(channel);
+    }
+}