Whats the best way to receive MSMQ messages.
I used the following code, but after receiving MSMQ messages not getting removed in Queue
var msgEnumerator = myQueue.GetMessageEnumerator2();
var messages = new List<System.Messaging.Message>();
while (msgEnumerator.MoveNext(new TimeSpan(0, 0, 1)))
{
var msg = myQueue.ReceiveById(msgEnumerator.Current.Id, new TimeSpan(0, 0, 1));
messages.Add(msg);
for (int i = 0; i < messages.Capacity; i++)
{
String DataMessages = messages[i].ToString();
}
But i cant receive messages.
How to receive those messages.
I would use asynchronous MessageQueue.BeginPeek to start listening on the queue:
queue.BeginPeek();
Then register a handler with the MessageQueue.PeekCompleted event:
queue.PeekCompleted += new PeekCompletedEventHandler(MessageHasBeenReceived);
Then in your handler use MessageQueue.EndPeek to access the message. Remember to call BeginPeek again.
private void MessageHasBeenReceived(object sender, PeekCompletedEventArgs e)
{
// Get message
var msg = queue.EndPeek(e.AsyncResult);
// Do message processing here
....
// Remove message from queue
queue.ReceiveById(msg.Id);
// Listen for more messages
queue.BeginPeek();
}
See here for MSDN example.
Related
I'm using MassTransit with Reactive Extensions to stream messages from the queue in batches. Since the behaviour isn't the same as a normal consumer I need to be able to send a message to the error queue if it fails an x number of times.
I've looked through the MassTransit source code and posted on the google groups and can't find an anwser.
Is this available on the ConsumeContext interface? Or is this even possible?
Here is my code. I've removed some of it to make it simpler.
_busControl = Bus.Factory.CreateUsingRabbitMq(cfg =>
{
var host = cfg.Host(new Uri("rabbitmq://localhost/"), h =>
{
h.Username("guest");
h.Password("guest");
});
cfg.UseInMemoryScheduler();
cfg.ReceiveEndpoint(host, "customer_update_queue", e =>
{
var _observer = new ObservableObserver<ConsumeContext<Customer>>();
_observer.Buffer(TimeSpan.FromMilliseconds(1000)).Subscribe(OnNext);
e.Observer(_observer);
});
});
private void OnNext(IList<ConsumeContext<Customer>> messages)
{
foreach (var consumeContext in messages)
{
Console.WriteLine("Content: " + consumeContext.Message.Content);
if (consumeContext.Message.RetryCount > 3)
{
// I want to be able to send to the error queue
consumeContext.SendToErrorQueue()
}
}
}
I've found a work around by using the RabbitMQ client mixed with MassTransit. Since I can't throw an exception when using an Observable and therefore no error queue is created. I create it manually using the RabbitMQ client like below.
ConnectionFactory factory = new ConnectionFactory();
factory.HostName = "localhost";
factory.UserName = "guest";
factory.Password = "guest";
using (IConnection connection = factory.CreateConnection())
{
using (IModel model = connection.CreateModel())
{
string exchangeName = "customer_update_queue_error";
string queueName = "customer_update_queue_error";
string routingKey = "";
model.ExchangeDeclare(exchangeName, ExchangeType.Fanout);
model.QueueDeclare(queueName, false, false, false, null);
model.QueueBind(queueName, exchangeName, routingKey);
}
}
The send part is to send it directly to the message queue if it fails an x amount of times like so.
consumeContext.Send(new Uri("rabbitmq://localhost/customer_update_queue_error"), consumeContext.Message);
Hopefully the batch feature will be implemented soon and I can use that instead.
https://github.com/MassTransit/MassTransit/issues/800
I'm developing a cloud service (worker role) for collecting data from a number of instruments. These instruments reports data randomly every minute or so. The service itself is not performance critical and doesn't need to be asynchronous. The instruments are able to resend their data up to an hour on failed connection attempt.
I have tried several implementations for my cloud service including this one:
http://msdn.microsoft.com/en-us/library/system.net.sockets.tcplistener.stop(v=vs.110).aspx
But all of them hang my cloud server sooner or later (sometimes within an hour).
I suspect something is wrong with my code. I have a lot of logging in my code but I get no errors. The service just stops to receive incoming connections.
In Azure portal it seems like the service is running fine. No error logs and no suspicious cpu usage etc.
If I restart the service it will run fine again until it hangs next time.
Would be most grateful if someone could help me with this.
public class WorkerRole : RoleEntryPoint
{
private LoggingService _loggingService;
public override void Run()
{
_loggingService = new LoggingService();
StartListeningForIncommingTCPConnections();
}
private void StartListeningForIncommingTCPConnections()
{
TcpListener listener = null;
try
{
listener = new TcpListener(RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["WatchMeEndpoint"].IPEndpoint);
listener.Start();
while (true)
{
_loggingService.Log(SeverityLevel.Info, "Waiting for connection...");
var client = listener.AcceptTcpClient();
var remoteEndPoint = client.Client != null ? client.Client.RemoteEndPoint.ToString() : "Unknown";
_loggingService.Log(SeverityLevel.Info, String.Format("Connected to {0}", remoteEndPoint));
var netStream = client.GetStream();
var data = String.Empty;
using (var reader = new StreamReader(netStream, Encoding.ASCII))
{
data = reader.ReadToEnd();
}
_loggingService.Log(SeverityLevel.Info, "Received data: " + data);
ProcessData(data); //data is processed and stored in database (all resources are released when done)
client.Close();
_loggingService.Log(SeverityLevel.Info, String.Format("Connection closed for {0}", remoteEndPoint));
}
}
catch (Exception exception)
{
_loggingService.Log(SeverityLevel.Error, exception.Message);
}
finally
{
if (listener != null)
listener.Stop();
}
}
private void ProcessData(String data)
{
try
{
var processor = new Processor();
var lines = data.Split('\n');
foreach (var line in lines)
processor.ProcessLine(line);
processor.ProcessMessage();
}
catch (Exception ex)
{
_loggingService.Log(SeverityLevel.Error, ex.Message);
throw new Exception(ex.InnerException.Message);
}
}
}
One strange observation i just did:
I checked the log recently and no instrument has connected for the last 30 minutes (which indicates that the service is down).
I connected to the service myself via a TCP client i've written myself and uploaded some test data.
This worked fine.
When I checked the log again my test data had been stored.
The strange thing is, that 4 other instruments had connected about the same time and send their data successfully.
Why couldn't they connect by themself before I connected with my test client?
Also, what does this setting in .csdef do for an InputEndpoint, idleTimeoutInMinutes?
===============================================
Edit:
Since a cuple of days back my cloud service has been running successfully.
Unfortunately this morning last log entry was from this line:
_loggingService.Log(SeverityLevel.Info, String.Format("Connected to {0}", remoteEndPoint));
No other connections could be made after this. Not even from my own test TCP client (didn't get any error though, but no data was stored and no new logs).
This makes me think that following code causes the service to hang:
var netStream = client.GetStream();
var data = String.Empty;
using (var reader = new StreamReader(netStream, Encoding.ASCII))
{
data = reader.ReadToEnd();
}
I've read somewhere that StremReader's ReadToEnd() could hang. Is this possible?
I have now changed this piece of code to this:
int i;
var bytes = new Byte[256];
var data = new StringBuilder();
const int dataLimit = 10;
var dataCount = 0;
while ((i = netStream.Read(bytes, 0, bytes.Length)) != 0)
{
data.Append(Encoding.ASCII.GetString(bytes, 0, i));
if (dataCount >= dataLimit)
{
_loggingService.Log(SeverityLevel.Error, "Reached data limit");
break;
}
dataCount++;
}
Another explanation could be something hanging in the database. I use the SqlConnection and SqlCommand classes to read and write to my database. I always close my connection afterwards (finally block).
SqlConnection and SqlCommand should have default timeouts, right?
===============================================
Edit:
After some more debugging I found out that when the service wasn't responding it "hanged" on this line of code:
while ((i = netStream.Read(bytes, 0, bytes.Length)) != 0)
After some digging I found out that the NetStream class and its read methods could actually hang. Even though MS declares otherwise.
NetworkStream read hangs
I've now changed my code into this:
Thread thread = null;
var task = Task.Factory.StartNew(() =>
{
thread = Thread.CurrentThread;
while ((i = netStream.Read(bytes, 0, bytes.Length)) != 0)
{
// Translate data bytes to a ASCII string.
data.Append(Encoding.ASCII.GetString(bytes, 0, i));
}
streamReadSucceeded = true;
});
task.Wait(5000);
if (streamReadSucceeded)
{
//Process data
}
else
{
thread.Abort();
}
Hopefully this will stop the hanging.
I'd say that part of your problem is you are processing your data on the thread that listens for connections from clients. This would prevent new clients from connecting if another client has started a long running operation of some type. I'd suggest you defer your processing to worker threads thus freeing the "listener" thread to accept new connections.
Another problem you could be experiencing, if your service throws an error, then the service will stop accepting connections as well.
private static void ListenForClients()
{
tcpListener.Start();
while (true)
{
TcpClient client = tcpListener.AcceptTcpClient();
Thread clientThread = new Thread(new ParameterizedThreadStart(HandleClientComm));
clientThread.Start(client);
}
}
private static void HandleClientComm(object obj)
{
try
{
using(TcpClient tcpClient = (TcpClient)obj)
{
Console.WriteLine("Got Client...");
using (NetworkStream clientStream = tcpClient.GetStream())
using (StreamWriter writer = new StreamWriter(clientStream))
using(StreamReader reader = new StreamReader(clientStream))
{
//do stuff
}
}
}
catch(Exception ex)
{
}
}
I am developing a chat using quickblox but I am having some problems when I open a new chat. Suddenly I received all the messages that others users sends to me when I was desconnected. The problem is that when I start a chat with user A, I receive the chats from users B, C, D.. in user A chat room.
I have find the way to only show the A users. But the problem is that the server has already sent to me the "disconnected" messages, so when I start a chat to B I do not receive any text because the message that the user B sent to me has been delivered (and ommitted) while I was chating with user A.
How can I do to receive the pending messages (kind of history) or to just retreive the message of the chat I am logged in?
A piece of my code:
// Create Connection.
Connection.DEBUG_ENABLED = true;
config = new ConnectionConfiguration(CHAT_SERVER);
connection = new XMPPConnection(config);
try {
connection.connect();
connection.login(chatLogin, password);
// Create Chat Manager.
chatManager = connection.getChatManager();
// Create Chat.
chat = chatManager.createChat(friendLogin, null);
// // Set listener for outcoming messages.
// chatManager.addChatListener(chatManagerListener);
// Accept only messages from
String from_messages = Integer.toString(receiver_chat_id);
PacketFilter filter = new AndFilter(new PacketTypeFilter(Message.class),
new FromContainsFilter(from_messages+"-3758#chat.quickblox.com"));
// Collect these messages
PacketCollector collector = connection.createPacketCollector(filter);
Packet packet = collector.pollResult();
PacketListener myListener = new PacketListener() {
public void processPacket(Packet packet) {
if (packet instanceof Message) {
Message msg = (Message) packet;
if(msg!=null){
// Process message
System.out.println("Rebem missatge: " +msg.getBody());
}
}
}
};
// Register the listener.
connection.addPacketListener(myListener, filter);
// Set listener for detect Receiver Status
if (connection.isConnected()){
roster = connection.getRoster();
roster.addRosterListener(new RosterListener() {
public void entriesDeleted(Collection<String> addresses) {}
public void entriesUpdated(Collection<String> addresses) {}
public void presenceChanged(Presence presence) {}
public void entriesAdded(Collection<String> arg0) {}
});
}
Make a arraylist and store the receiving offline messages into that array-list. you could add a code in your processPacket(Packet packet) function to add incoming messages to the array-list. or you could use Multimaps(Google Guava) to store all the incoming messages with the key. and when you open the activity that displays the messages from the certain person you could match the name of that person with the key(stored in multimap) and displays the message of that certain person. And the better option is to store all the incomming and outgoing message chat with the certain person so that you could show all the previous chat then you open up the activity.
My AS3 client program does not receive all the data that was sent to it when sending a lot of messages. I do know its not my server causing this problem because all the messages are received and send correctly. My as3 client just does not receive all the data send.
private function socketData(event:ProgressEvent):void {
while(this.socket.bytesAvailable}
var str:String = this.socket.readUTFBytes(this.socket.bytesAvailable);
trace(str);
}
}
Does any of you know a solution?
I had the same issue this afternoon. Finally i came with a solution:
In fact, you have to read the message byte by byte like so:
private function socketData (evt:ProgressEvent):void {
var msg:String = ""; // create a buffer
while (socket.bytesAvailable) { // while there is byte to read
var byte:int = socket.readByte();
if (byte==0) { // if we read the end byte
trace(msg); // treat your message
msg = ""; // free the buffer
} else {
msg += String.fromCharCode(byte); // else, we add the byte to our buffer
}
}
}
I hope this will help you :)
Problem solved, I just had to open the port on my router.
I am using .net framework to work with ws queues. Is it possible to remove/delete a message from a queue?
Retrieving it will remove it from the queue. You can then discard the retrieved message if you don't want to do anything with it.
// Hit up MSMQ for list of new messages
var queuedMessages = myMessageQueue.GetAllMessages();
// Receive actual message to remove from the message queue
var messages = new List<Message>();
foreach (var queuedMessage in queuedMessages)
{
// Receive the message, which removes it from the queue.
try
{
messages.Add(this.messageQueue.ReceiveById(queuedMessage.Id));
}
// If it's already been removed, we skip over it.
// TODO: Should try to catch only the "removed" exception
catch (Exception)
{
continue;
}
}
return messages;