Why do a get a DeathWatchNotification when running this console app:
class Program
{
private static ActorSystem TestSystem;
static void Main(string[] args)
{
TestSystem = ActorSystem.Create("TestSystem");
TestSystem.ActorOf<TestActor>("Test");
Console.WriteLine("Press a key to shutdown actor system");
Console.ReadKey();
TestSystem.Shutdown();
TestSystem.AwaitTermination();
Console.WriteLine("Press a key to quit");
Console.ReadKey();
}
}
public class TestActor : ReceiveActor
{
public TestActor()
{
}
protected override void Unhandled(object message)
{
Console.WriteLine("unhandled message");
//Do something with the message.
}
}
public class TestMessage
{
}
Obviously I haven't sent any messages and the actor doesn't do anything. It's not a huge deal but I'm concerned I'll miss a real problem if I ignore this message.
As I understand, DeathWatchNotification is a special type of message, that actor sends to its watcher(s) when it's getting terminated.
For example, consider this piece of code, that I got from the source of Akka.NET-1.0.4 (ActorCell.DeatWatch.cs file):
private void SendTerminated(bool ifLocal, IActorRef watcher)
{
if (((IActorRefScope)watcher).IsLocal == ifLocal && !watcher.Equals(Parent))
{
watcher.Tell(new DeathWatchNotification(Self, true, false));
}
}
Related
I am trying to log any information or exception that occurs during message sending in RabbitMQ, for that I tried to add ConnectionListener on the existing connection factory.
kRabbitTemplate.getConnectionFactory().addConnectionListener(new ConnectionListener() {
#Override
public void onCreate(Connection connection) {
System.out.println("Connection Created");
}
#Override
public void onShutDown(ShutdownSignalException signal) {
System.out.println("Connection Shutdown "+signal.getMessage());
}
});
kRabbitTemplate.convertAndSend(exchange, routingkey, empDTO);
To test the exception scenario, I unbind and even deleted the queue from RabbitMQ console. But I did not get any exception or any shutdown method call.
Although, When I stopped RabbitMQ service, I got
Exception in thread "Thread-5" org.springframework.amqp.AmqpConnectException: java.net.ConnectException: Connection refused: connect
But this exception is not from the listener I added.
I want to know
Why I did not get any exception or call from shutdown method
How can I use ConnectionListner and/or ChannelListner for logging failure/success of message delivery.
Can we use the AMQP appender, if yes how can we do that? (any example / tutorial)
What are the other approaches to ensure the message is sent?
Note: I do not want to use the publisher confirm the approach.
Connection Refused is not a ShutdownSignalException - the connection was never established because the broker is not present on the server/port.
You can't use the listeners to confirm delivery or return of individual messages; use publisher confirms and returns for that.
https://docs.spring.io/spring-amqp/docs/current/reference/html/#publishing-is-async
See the documentation for how to use the appenders.
https://docs.spring.io/spring-amqp/docs/current/reference/html/#logging
EDIT
To get notified of failures to connect, you currently need to use other techniques, depending on whether you are sending or receiving.
Here is an example that shows how:
#SpringBootApplication
public class So66882099Application {
private static final Logger log = LoggerFactory.getLogger(So66882099Application.class);
public static void main(String[] args) {
SpringApplication.run(So66882099Application.class, args);
}
#RabbitListener(queues = "foo")
void listen(String in) {
}
// consumer side listeners for no connection
#EventListener
void consumerFailed(ListenerContainerConsumerFailedEvent event) {
log.error(event + " via event listener");
if (event.getThrowable() instanceof AmqpConnectException) {
log.error("Broker down?");
}
}
// or
#Bean
ApplicationListener<ListenerContainerConsumerFailedEvent> eventListener() {
return event -> log.error(event + " via application listener");
}
// producer side - use a RetryListener
#Bean
RabbitTemplate template(ConnectionFactory cf) {
RabbitTemplate rabbitTemplate = new RabbitTemplate(cf);
RetryTemplate retry = new RetryTemplate();
// configure retries here as needed
retry.registerListener(new RetryListener() {
#Override
public <T, E extends Throwable> boolean open(RetryContext context, RetryCallback<T, E> callback) {
return true;
}
#Override
public <T, E extends Throwable> void onError(RetryContext context, RetryCallback<T, E> callback,
Throwable throwable) {
log.error("Send failed " + throwable.getMessage());
}
#Override
public <T, E extends Throwable> void close(RetryContext context, RetryCallback<T, E> callback,
Throwable throwable) {
}
});
rabbitTemplate.setRetryTemplate(retry);
return rabbitTemplate;
}
#Bean
public ApplicationRunner runner(RabbitTemplate template) {
return args -> {
try {
template.convertAndSend("foo", "bar");
}
catch (Exception e) {
e.printStackTrace();
}
};
}
}
Starting with this...
https://github.com/jeremytammik/RevitLookup/blob/master/CS/EventTrack/Events/ApplicationEvents.cs
I'm trying to add an event listener for a synchronization event. the code below throws an error stating that the m_app is null. Can i not subscribe to this event while Revit is starting up?
I was able to do this before with application.ViewActivated += ..... Im wondering if this has something to do with DB vs UI driven events and when they are allowed to be subscribed to? I just don't know.
namespace RevitModelHealth
{
public class checkHealth : IExternalApplication
{
// Document doc;
static public Autodesk.Revit.ApplicationServices.Application m_app = null;
public Result OnShutdown(UIControlledApplication application)
{
return Result.Succeeded;
}
public Result OnStartup(UIControlledApplication application)
{
m_app.DocumentSynchronizingWithCentral += new EventHandler<DocumentSynchronizingWithCentralEventArgs>(m_app_DocumentSavingToCentral);
return Result.Succeeded;
}
void m_app_DocumentSavingToCentral(object sender, Autodesk.Revit.DB.Events.DocumentSynchronizingWithCentralEventArgs e)
{
MessageBox.Show("asd","asd");
}
}
}
Here is updated code reflecting my response to the first answer. The message box opens when the document is loaded. No errors are thrown when I try to initialize the synchronization event handlers, however, neither of the message boxes open before or after a synchronization event.
public class checkHealth : IExternalApplication
{
// Document doc;
static public Autodesk.Revit.ApplicationServices.Application m_app;
public Result OnShutdown(UIControlledApplication application)
{
return Result.Succeeded;
}
public Result OnStartup(UIControlledApplication application)
{
application.ControlledApplication.DocumentOpened += new EventHandler<DocumentOpenedEventArgs>(app_DocOpened);
return Result.Succeeded;
}
public void app_DocOpened(object sender, DocumentOpenedEventArgs args)
{
MessageBox.Show("asd","asd");
m_app.DocumentSynchronizingWithCentral += new EventHandler<DocumentSynchronizingWithCentralEventArgs>(m_app_DocumentSavingToCentral);
m_app.DocumentSynchronizedWithCentral += new EventHandler<Autodesk.Revit.DB.Events.DocumentSynchronizedWithCentralEventArgs>(m_app_DocumentSavedToCentral);
}
void m_app_DocumentSavingToCentral(object sender, Autodesk.Revit.DB.Events.DocumentSynchronizingWithCentralEventArgs e)
{
MessageBox.Show("sync", "sync");
}
void m_app_DocumentSavedToCentral(object sender, Autodesk.Revit.DB.Events.DocumentSynchronizedWithCentralEventArgs e)
{
MessageBox.Show("Doone", "Done");
}
}
this worked.... Thanks largely in part to the SDK sample project EventsMonitor
namespace RevitModelHealth
{
public class checkHealth : IExternalApplication
{
public Result OnShutdown(UIControlledApplication application)
{
return Result.Succeeded;
}
public Result OnStartup(UIControlledApplication application)
{
application.ControlledApplication.DocumentSynchronizingWithCentral += new EventHandler<DocumentSynchronizingWithCentralEventArgs>(app_syncStart);
application.ControlledApplication.DocumentSynchronizedWithCentral += new EventHandler<DocumentSynchronizedWithCentralEventArgs>(app_syncOver);
return Result.Succeeded;
}
public void app_syncStart(object o ,DocumentSynchronizingWithCentralEventArgs args)
{
MessageBox.Show("","Stasrting");
}
public void app_syncOver(object o,DocumentSynchronizedWithCentralEventArgs args)
{
MessageBox.Show("", "Over");
}
}
}
Try
application.ControlledApplication.DocumentSynchronizingWithCentral += new EventHandler<DocumentSynchronizingWithCentralEventArgs>(m_app_DocumentSavingToCentral)
in your OnStartup() method.
The call is failing because instance member m_app is initialized to null.
The UIApplication.ControlledApplication object that raises the DocumentSynchronizingWithCentralEventArgs is being accessible from the parameter to OnStartup.
You can try this:
public void app_DocOpened(object sender, DocumentOpenedEventArgs args)
{
MessageBox.Show("asd","asd");
Autodesk.Revit.ApplicationServices.Application m_app = args.Document.Application;
m_app.DocumentSynchronizingWithCentral += new EventHandler<DocumentSynchronizingWithCentralEventArgs>(m_app_DocumentSavingToCentral);
m_app.DocumentSynchronizedWithCentral += new EventHandler<Autodesk.Revit.DB.Events.DocumentSynchronizedWithCentralEventArgs>(m_app_DocumentSavedToCentral);
}
We're building a WCF server (.NET 4.5). It will only use net.pipe transport.
When a client closes the PIPE connection, the server gets unhandled CommunicationException, and terminates.
Q1. How do I handle the CommunicationException so the server does not terminate and continues serving other clients?
Q2. In the handler, how do I get SessionId of the session that was aborted? I need this to do clean up some session-specific data.
Thanks in advance!
contract
[ServiceContract(CallbackContract = typeof(IContractCallback))]
public interface IContractServer
{
[OperationContract(IsOneWay = true)]
void Connect(bool status);
[OperationContract(IsOneWay = false)]
void Disconnect(IContractServer _channelCallback);
[OperationContract(IsOneWay = true)]
void Play(bool status);
}
service
[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
public class Service : IContractServer
{
public List<IContractCallback> _channeList = new List<IContractCallback>();
public void Connect(bool status)
{
IContractCallback a = OperationContext.Current.GetCallbackChannel<IContractCallback>();
int call = 0;
foreach (var callBack in _channeList)
{
if (callBack == a)
{
call++;
}
}
if (call == 0)
{
_channeList.Add(a);
a.ConnectCallback(true);
}
else
{
a.ConnectCallback(false);
}
}
public void Disconnect(IContractServer _channelCallback)
{
foreach (var contractCallback in _channeList)
{
if (contractCallback == _channelCallback)
{
_channeList.Remove(contractCallback);
}
}
}
public void Play(bool status)
{
foreach (var contractCallback in _channeList)
{
contractCallback.PlayCallback(status);
}
}
}
client
using System.ComponentModel;
using System.ServiceModel;
using System.Windows;
using Host;
namespace VideoPlayer
{
public partial class MainWindow : Window, IContractCallback
{
private IContractServer Proxy = null;
public MainWindow()
{
InitializeComponent();
InstanceContext context = new InstanceContext(this);
DuplexChannelFactory<IContractServer> factory = new DuplexChannelFactory<IContractServer>(context, new NetNamedPipeBinding(), "net.pipe://localhost");
Proxy = factory.CreateChannel();
Proxy.Connect(true);
}
public void ConnectCallback(bool status)
{
MessageBox.Show(status ? "connected" : "no connected");
}
public void PlayCallback(bool status)
{
if (status)
{
MessageBox.Show("status true");
}
else
{
MessageBox.Show("status false");
}
}
private void ButtonPlay(object sender, RoutedEventArgs e)
{
Proxy.Play(true);
}
private void MainWindow_OnClosing(object sender, CancelEventArgs e)
{
//хочу отправить сообщение о закрытии
Proxy.Disconnect(Proxy);
}
I faced with this problem before in my duplex services when an event raised from server side the exception occurred if there was no alive channel between client and server so server dropped to Fault state and all next requests won't be responded,
For this reason I came to this conclusion to check the channel and if it was alive then let call back methods to be raised.
In service side the trick would be like ↓
bool IsChannelAlive()
{
Logging logging = new Logging(LogFile);
try
{
if (((ICommunicationObject)_callbackChannel).State == CommunicationState.Opened)
{
logging.Log(LoggingMode.Prompt, "Channeld is still alive, can raise events...");
return true;
}
}
catch (Exception exp)
{
logging.Log(LoggingMode.Error, "IsChannelAlive()=> failed, EXP: {0}", exp);
}
logging.Log(LoggingMode.Warning, "Channeld is not alive so events won't raised...");
return false;
}
and in one of my events I use it like :
void stran_OperationTimedOut(object sender, EventArgs e)
{
if (IsChannelAlive())
_callbackChannel.OnOperationTimedOut();
}
But for a while I use this trick to know closed channel to do something:
public ImportService()
{
//Handle ContextClose to Audit all actions made in session
OperationContext.Current.InstanceContext.Closed += delegate
{
//Here
};
}
which is not reliable.
I am still using that IsAliveChannel() in my services.
Hope this answer resolve your problem or give you the clue.
When working with SQL Azure, if I create my own RetryPolicy, e.g.:
var retryStrategy = new FixedInterval(3, TimeSpan.FromSeconds(10));
var retryPolicySQL = new RetryPolicy<SqlAzureTransientErrorDetectionStrategy>(retryStrategy);
retryPolicySQL.Retrying += ....;
I am able to get notified when a retry is happening which is useful to log.
However, if I use what seems to be the new recommended strategy with EF6 and Azure - i.e. a custom DbConfiguration class something like this:
public class MyConfiguration : DbConfiguration
{
public MyConfiguration()
{
this.SetExecutionStrategy("System.Data.SqlClient", () =>
{
var strat = new SqlAzureExecutionStrategy();
// strat. No events
return strat;
});
}
}
I can't seem to find a way to hook into the retrying process. Is there a way to do this?
Implement the protected method called ShouldRetryOn by subclassing from SqlAzureExecutionStrategy. In that method you could put your logic to log or hook it into a handler as I show below.
public delegate void ChangedEventHandler(object sender, EventArgs e);
public class MyStrategy : SqlAzureExecutionStrategy
{
public event ChangedEventHandler Changed;
protected override bool ShouldRetryOn(Exception exception)
{
OnChanged(EventArgs.Empty);
return base.ShouldRetryOn(exception);
}
protected virtual void OnChanged(EventArgs e)
{
if (Changed != null)
Changed(this, e);
}
}
If you would perfer to just log the exception or the retry, you can do as follows:
public class LoggedSqlAzureExecutionStrategy : SqlAzureExecutionStrategy
{
protected override bool ShouldRetryOn(Exception exception)
{
var shouldRetry = base.ShouldRetryOn(exception);
if (shouldRetry)
{
// log retry
}
return shouldRetry;
}
}
I have a sample service to test WCF net.tcp communication. It is very simple service and all it does is subscribing a client to the service and then calls callbackchannel to notify all connected clients about broadcasted message. The service is hosted inside IIS 7.5.
Here is service code and test client to test it.
[ServiceContract(CallbackContract = typeof(ISampleServiceCallBack), SessionMode = SessionMode.Required)]
public interface ISampleCuratioService
{
[OperationContract(IsOneWay = true)]
void SubcribeToService(string sub);
[OperationContract]
string GetData(int value);
[OperationContract(IsOneWay = true)]
void Broadcast(string message);
}
public interface ISampleServiceCallBack
{
[OperationContract(IsOneWay = true)]
void NotifyClient(string message);
}
Here is the service implementation:
[ServiceBehavior(Name = "CuratioCSMService", InstanceContextMode = InstanceContextMode.PerSession)]
public class Service1 : ISampleCuratioService
{
private static List<ISampleServiceCallBack> JoinedClien = new List<ISampleServiceCallBack>();
public void SubcribeToService(string sub)
{
var subscriber = OperationContext.Current.GetCallbackChannel<ISampleServiceCallBack>();
if (!JoinedClien.Contains(subscriber))
{
JoinedClien.Add(subscriber);
}
}
public string GetData(int value)
{
return string.Format("You entered: {0}", value);
}
public void Broadcast(string message)
{
JoinedClien.ForEach(c => c.NotifyClient("message was received " + message));
}
}
I can not understand the behavior I get when running it. After the first client runs everything works fine but as I close and open test client app, it throws exception notifying that channel can not be used for communication as it is in fault state.
This is sample test client:
static void Main(string[] args)
{
var callneckclient = new ServiceClientProxy();
var client = new SampleCuratioServiceClient(new InstanceContext(callneckclient));
client.SubcribeToService("me");
Console.ReadLine();
for (int i = 0; i < 15; i++)
{
Console.WriteLine(client.GetData(5));
client.Broadcast("this is from client me");
}
client.Close();
Console.Read();
}
public class ServiceClientProxy : ISampleCuratioServiceCallback, IDisposable
{
public void NotifyClient(string message)
{
Console.WriteLine(message);
}
public void Dispose()
{
GC.SuppressFinalize(this);
}
}
The situation gets even buggy when I run 5 clients. Non of those send or receive messages.
When a client calls SubcribeToService you add its operation context to a List called JoinedClien.
When you call Broadcast in your server, you call the method NotifyClient on all collected operation contexts for every client that has ever connected.
The problem is, that a disconnected client won't get removed from your JoinedClien list.
When you try to call an operation method on a disconnected operation context, you get the channel is in faulted state error.
To work around, you should subscribe to the Channel_Closed and Channel_Faulted events and also catch the CommunicationException when calling back into your clients and remove the operation context of the faulted clients:
public void Broadcast(string message)
{
// copy list of clients
List<OperationContext> clientsCopy = new List<OperationContext>();
lock(JoinedClien) {
clientsCopy.AddRange(JoinedClien);
}
// send message and collect faulted clients in separate list
List<OperationContext> clientsToRemove = new List<OperationContext>();
foreach (var c in JoinedClien)
{
try {
c.NotifyClient("message was received " + message));
}
catch (CommunicationException ex) {
clientsToRemove.Add(c);
}
}
foreach (var c in clientsToRemove)
{
lock(JoinedClien) {
if(JoinedClien.Contains(c))
JoinedClien.Remove(c);
}
}
}
When adding new clients you have to lock that operation, too:
var subscriber = OperationContext.Current.GetCallbackChannel<ISampleServiceCallBack>();
lock(JoinedClien)
{
if (!JoinedClien.Contains(subscriber))
{
JoinedClien.Add(subscriber);
}
}