Using Advanced Queueing v4.0.10.2

EXEC DBMS_AQADM.CREATE_QUEUE_TABLE
      (queue_table => 'MSG_QUEUE_TABLE',
       queue_payload_type => 'myxml',
       comment => 'Message queue table');
END;

BEGIN
DBMS_AQADM.CREATE_QUEUE ( queue_name => 'MSG_QUEUE', queue_table => 'MSG_QUEUE_TABLE', comment => 'This queue contains pending messages.');
END;

BEGIN
DBMS_AQADM.START_QUEUE
(queue_name => 'MSG_QUEUE');
END;

using EnterpriseDB.EDBClient;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AQXml
{
    class MyXML
    {
        public string value { get; set; }
    }
    class Program
    {
        static void Main(string[] args)
        {
            int messagesToSend = 1;
            if (args.Length > 0 && !string.IsNullOrEmpty(args[0]))
            {
                messagesToSend = int.Parse(args[0]);
            }
            for (int i = 0; i < 5; i++)
            {
                EnqueMsg("test message: " + i);
            }
        }

      private static EDBConnection GetConnection()
        {
            string connectionString = "Server=127.0.0.1;Host=127.0.0.1;Port=5444;User Id=enterprisedb;Password=test;Database=edb;Timeout=999";
            EDBConnection connection = new EDBConnection(connectionString);
            connection.Open();
            return connection;
        }


        private static string ByteArrayToString(byte[] byteArray)
        {
            // Sanity check if it's null so we don't incur overhead of an exception
            if (byteArray == null)
            {
                return string.Empty;
            }
            try
            {
                StringBuilder hex = new StringBuilder(byteArray.Length * 2);
                foreach (byte b in byteArray)
                {
                    hex.AppendFormat("{0:x2}", b);
                }

                return hex.ToString().ToUpper();
            }
            catch
            {
                return string.Empty;
            }
        }

        private static bool EnqueMsg(string msg)
        {
            EDBConnection con = GetConnection();
            using (EDBAQQueue queue = new EDBAQQueue("MSG_QUEUE", con))
            {
                queue.MessageType = EDBAQMessageType.Xml;
                EDBTransaction txn = queue.Connection.BeginTransaction();
                QueuedEntities.Message queuedMessage = new QueuedEntities.Message() { MessageText = msg };

                try
                {
                    string rootElementName = queuedMessage.GetType().Name;
                    if (rootElementName.IndexOf(".") != -1)
                    {
                        rootElementName = rootElementName.Split('.').Last();
                    }

                    string xml = new Utils.XmlFragmentSerializer<QueuedEntities.Message>().Serialize(queuedMessage);
                    EDBAQMessage queMsg = new EDBAQMessage();
                    queMsg.Payload = new MyXML { value = xml };
                    queue.MessageType = EDBAQMessageType.Udt;
                    queue.UdtTypeName = "myxml";
                    queue.Enqueue(queMsg);
                    var messageId = ByteArrayToString((byte[])queMsg.MessageId);
                    Console.WriteLine("MessageID: " + messageId);
                    txn.Commit();
                    queMsg = null;
                    xml = null;
                    rootElementName = null;
                    return true;
                }
                catch (Exception ex)
                {
                    txn?.Rollback();
                    Console.WriteLine("Failed to enqueue message.");
                    Console.WriteLine(ex.ToString());
                    return false;
                }
                finally
                {
                    queue?.Connection?.Dispose();
                }
            }
        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using EnterpriseDB.EDBClient;

namespace DequeueXML
{
    class MyXML
    {
        public string value { get; set; }
    }
    class Program
    {
        static void Main(string[] args)
        {
            DequeMsg();
        }


        private static EDBConnection GetConnection()
        {
            string connectionString = "Server=127.0.0.1;Host=127.0.0.1;Port=5444;User Id=enterprisedb;Password=test;Database=edb;Timeout=999";
            EDBConnection connection = new EDBConnection(connectionString);
            connection.Open();
            return connection;
        }


        private static string ByteArrayToString(byte[] byteArray)
        {
            // Sanity check if it's null so we don't incur overhead of an exception
            if (byteArray == null)
            {
                return string.Empty;
            }
            try
            {
                StringBuilder hex = new StringBuilder(byteArray.Length * 2);
                foreach (byte b in byteArray)
                {
                    hex.AppendFormat("{0:x2}", b);
                }

                return hex.ToString().ToUpper();
            }
            catch
            {
                return string.Empty;
            }
        }
        public static void DequeMsg(int waitTime = 10)
        {
            EDBConnection con = GetConnection();
            using (EDBAQQueue queueListen = new EDBAQQueue("MSG_QUEUE", con))
            {
                queueListen.UdtTypeName = "myxml";
                queueListen.DequeueOptions.Navigation = EDBAQNavigationMode.FIRST_MESSAGE;
                queueListen.DequeueOptions.Visibility = EDBAQVisibility.ON_COMMIT;
                queueListen.DequeueOptions.Wait = 1;
                EDBTransaction txn = null;

                while (1 == 1)
                    {

                    if (queueListen.Connection.State == System.Data.ConnectionState.Closed)
                    {
                        queueListen.Connection.Open();
                    }

                    string messageId = "Unknown";
                    try
                    {
                        // the listen function is a blocking function. It will Wait the specified waitTime or until a
                        // message is received.
                        Console.WriteLine("Listening...");
                        string v = queueListen.Listen(null, waitTime);
                        // If we are waiting for a message and we specify a Wait time,
                        // then if there are no more messages, we want to just bounce out.
                        if (waitTime > -1 && v == null)
                        {
                            Console.WriteLine("No message received during Wait period.");
                            Console.WriteLine();
                            continue;
                        }

                        // once we're here that means a message has been detected in the queue. Let's deal with it.
                        txn = queueListen.Connection.BeginTransaction();

                        Console.WriteLine("Attempting to dequeue message...");
                        // dequeue the message
                        EDBAQMessage deqMsg;
                        try
                        {
                            deqMsg = queueListen.Dequeue();
                        }
                        catch (Exception ex)
                        {
                            if (ex.Message.Contains("ORA-25228"))
                            {
                                Console.WriteLine("Message was not there.  Another process must have picked it up.");
                                Console.WriteLine();
                                txn.Rollback();
                                continue;
                            }
                            else
                            {
                                throw;
                            }
                        }

                        messageId = ByteArrayToString((byte[])deqMsg.MessageId);
                        if (deqMsg != null)
                        {
                            Console.WriteLine("Processing received message...");
                            // process the message payload
                            MyXML obj = new MyXML();
                            queueListen.Map<MyXML>(deqMsg.Payload, obj);

                            QueuedEntities.Message msg = new Utils.XmlFragmentSerializer<QueuedEntities.Message>().Deserialize(obj.value);

                            Console.WriteLine("Received Message:");
                            Console.WriteLine("MessageID: " + messageId);
                            Console.WriteLine("Message: " + msg.MessageText);
                            Console.WriteLine("Enqueue Time" + queueListen.MessageProperties.EnqueueTime);

                            txn.Commit();

                            Console.WriteLine("Finished processing message");
                            Console.WriteLine();

                        }
                        else
                        {
                            Console.WriteLine("Message was not dequeued.");
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine("Failed To dequeue or process the dequeued message.");
                        Console.WriteLine(ex.ToString());
                        Console.WriteLine();
                        if (txn != null)
                        {
                            txn.Rollback();
                            if (txn != null)
                            {
                                txn.Dispose();
                            }
                        }
                    }
                }
            }

        }
    }
}