I want the server to constantly track for available clients using WCF Discovery.
public void Start()
{
findCriteria = new FindCriteria(typeof(ITestRunnerAgent))
{
Scopes = {new Uri(scope)},
Duration = TimeSpan.FromMilliseconds(DiscoveryIntervalInMiliseconds)
};
discoveryClient = GetInitilizedDisoveryClient();
discoveryClient.FindAsync(findCriteria);
}
private DiscoveryClient GetInitilizedDisoveryClient()
{
var client = new DiscoveryClient(new UdpDiscoveryEndpoint());
client.FindProgressChanged += OnFindProgressChanged;
client.FindCompleted += OnFindCompleted;
return client;
}
private void OnFindCompleted(object sender, FindCompletedEventArgs e)
{
if (!e.Cancelled)
{
// HERE! Sometimes e.Error is not null, but as described in question
discoveryClient.FindAsync(findCriteria);
}
}
Unfortunately, sometimes at the point specified by comment i get an aborted Udp channel:
The communication object,
System.ServiceModel.Channels.UdpChannelFactory+ClientUdpDuplexChannel,
cannot be used for communication
because it has been Aborted.
Has anyone ideas why?
It could be that some network infrastructure at your office is droping the connections.
You should write your code to check for aborted communication, and recover from it.
To recover you could close down the aborted channel and create a new one.
Well, this doesn't answer your question, but I feel a little wary about your code. It seems fundamentally correct, but it feels like your discovery could be running very fast. I would implement recurring discovery in a separate thread with some sleep time just to make the network happier. Just a thought to clean up the code. Sorry if this doesn't help.
public void Start()
{
var bw = new System.ComponentModel.BackgroundWorker();
bw.DoWork += new System.ComponentModel.DoWorkEventHandler(DiscoveryThread);
bw.RunWorkerAsync();
}
private void DiscoveryThread(object sender, System.ComponentModel.DoWorkEventArgs e)
{
var client = new DiscoveryClient(new UdpDiscoveryEndpoint());
var findCriteria = new FindCriteria(typeof(ITestRunnerAgent))
{
Scopes = {new Uri(scope)},
Duration = TimeSpan.FromMilliseconds(DiscoveryIntervalInMiliseconds)
};
while(true)
{
client.Find(findCriteria);
// lock, clear, and add discovered endpoints to a global List of some sort
System.Threading.Thread.Sleep(3000);
}
}
As it is asynchronous operation the thread terminates after executing FindAsync(criteria) method. just wrote Console.Readline() after method call or use Autoreset event hold the thread.
Related
I want to be able to used NServiceBus to add a message on a queue in RabbitMQ. I dont want to handle it yet so just want to see an item on the queue, my code is as follows, but I get this error when I run it?
I have been trying to look at the documentation but is seems overly confusing. I am familar with RabbitMq and using it as is or with the Rabbit client library, but NService bus seems to complicate and confuse the situation!
using Shared;
using System;
using System.Threading.Tasks;
namespace NServiceBus.RabbitMqTest
{
class Program
{
static async Task Main(string[] args)
{
var endpointConfiguration = new EndpointConfiguration("UserChanged");
var transport = endpointConfiguration.UseTransport<RabbitMQTransport>();
transport.UseConventionalRoutingTopology();
transport.ConnectionString("host=localhost;username=guest;password=guest");
//transport.Routing().RouteToEndpoint(typeof(MyCommand), "Samples.RabbitMQ.SimpleReceiver");
endpointConfiguration.EnableInstallers();
var endpointInstance = await Endpoint.Start(endpointConfiguration).ConfigureAwait(false);
await SendMessages(endpointInstance);
//await endpointInstance.Publish(new UserChanged { UserId = 76 });
await endpointInstance.Stop().ConfigureAwait(false);
}
static async Task SendMessages(IMessageSession messageSession)
{
Console.WriteLine("Press [e] to publish an event. Press [Esc] to exit.");
while (true)
{
var input = Console.ReadKey();
Console.WriteLine();
switch (input.Key)
{
//case ConsoleKey.C:
// await messageSession.Send(new MyCommand());
// break;
case ConsoleKey.E:
await messageSession.Publish(new UserChanged { UserId = 87 });
break;
case ConsoleKey.Escape:
return;
}
}
}
}
}
Your endpoint is publishing the message as well as receiving it. Since there's no handler defined to handle the UserChanged messages (events), NServiceBus recoverability kicks in. Your options are
Declare the endpoint as send-only to avoid handling the messages when there are no handlers defined
Define a handler for UserChanged
I have a scenario where I want to "pull" messages of a RabbitMQ queue/topic and process them one at a time.
Specifically if there are already messages sitting on the queue when the consumer starts up.
I have tried the following with no success (meaning, each of these options reads the queue until it is either empty or until another thread closes the context).
1.Stopping route immediately it is first processed
final CamelContext context = new DefaultCamelContext();
try {
context.addRoutes(new RouteBuilder() {
#Override
public void configure() throws Exception {
RouteDefinition route = from("rabbitmq:harley?queue=IN&declare=false&autoDelete=false&hostname=localhost&portNumber=5672");
route.process(new Processor() {
Thread stopThread;
#Override
public void process(final Exchange exchange) throws Exception {
String name = exchange.getIn().getHeader(Exchange.FILE_NAME_ONLY, String.class);
String body = exchange.getIn().getBody(String.class);
// Doo some stuff
routeComplete[0] = true;
if (stopThread == null) {
stopThread = new Thread() {
#Override
public void run() {
try {
((DefaultCamelContext)exchange.getContext()).stopRoute("RabbitRoute");
} catch (Exception e) {}
}
};
}
stopThread.start();
}
});
}
});
context.start();
while(!routeComplete[0].booleanValue())
Thread.sleep(100);
context.stop();
}
Similar to 1 but using a latch rather than a while loop and sleep.
Using a PollingConsumer
final CamelContext context = new DefaultCamelContext();
context.start();
Endpoint re = context.getEndpoint(srcRoute);
re.start();
try {
PollingConsumer consumer = re.createPollingConsumer();
consumer.start();
Exchange exchange = consumer.receive();
String bb = exchange.getIn().getBody(String.class);
consumer.stop();
} catch(Exception e){
String mm = e.getMessage();
}
Using a ConsumerTemplate() - code similar to above.
I have also tried enabling preFetch and setting the max number of exchanges to 1.
None of these appear to work, if there are 3 messages on the queue, all are read before I am able to stop the route.
If I were to use the standard RabbitMQ Java API I would use a basicGet() call which lets me read a single message, but for other reasons I would prefer to use a Camel consumer.
Has anyone successfully been able to process a single message on a queue that holds multiple messages using a Camel RabbitMQ Consumer?
Thanks.
This is not the primary intention of the component as its for continued received. But I have created a ticket to look into supporting a basicGet (single receive). There is a new spring based rabbitmq component coming in 3.8 onwards so its going to be implemeneted there (first): https://issues.apache.org/jira/browse/CAMEL-16048
I have developed a small console application to test EWS StreamingSubscriptions / Notifications. In the past we used Push Notifications but ,in theory, when using StreamingNotifications I should be able to avoid creating a listener http endpoint and all the trouble with it (firewall, etc.).
So, from my local machine; I'm doing this:
static void Main(string[] args)
{
if (String.IsNullOrEmpty(ConfigurationManager.AppSettings["PrimaryLabUserId"]))
{
throw new ArgumentNullException("Please provide a value for PrimaryLabUserId in app.config");
}
_primaryLabUserId = ConfigurationManager.AppSettings["PrimaryLabUserId"];
string ServiceAccountName = ConfigurationManager.AppSettings["ExchangeServiceAccountName"];
string ServiceAccountPassword = ConfigurationManager.AppSettings["ExchangeServiceAccountPassword"];
_service = new ExchangeService(ExchangeVersion.Exchange2010_SP2);
_service.Credentials = new WebCredentials(ServiceAccountName, ServiceAccountPassword);
_service.AutodiscoverUrl(_primaryLabUserId, (x) => true);
_ewsUrl = _service.Url.AbsoluteUri;
var _connection = new StreamingSubscriptionConnection(_service, 30);
var sub = SubscribeForStreamingNotifications();
_connection.AddSubscription(sub);
_connection.OnDisconnect +=
new StreamingSubscriptionConnection.SubscriptionErrorDelegate(OnDisconnect);
// set up subscriptions here.
_connection.OnNotificationEvent +=
new StreamingSubscriptionConnection.NotificationEventDelegate(OnNewMail);
_connection.Open();
Console.WriteLine("Listening streaming...");
Console.ReadLine();
}
public static StreamingSubscription SubscribeForStreamingNotifications()
{
var folderIds = new List<FolderId>()
{
WellKnownFolderName.Inbox,
WellKnownFolderName.Calendar
};
var eventTypes = new List<EventType>();
eventTypes.Add(EventType.NewMail);
eventTypes.Add(EventType.Deleted);
eventTypes.Add(EventType.Moved);
eventTypes.Add(EventType.Created);
eventTypes.Add(EventType.Modified);
return _service.SubscribeToStreamingNotifications(folderIds, eventTypes.ToArray());
}
private static void OnNewMail(object sender, NotificationEventArgs args)
{
var test = args;
Console.WriteLine("Incoming");
}
The Subscription initializes OK, but when I send a new mail to the LabUser nothing happens. The Notification Event never fires. I tried the same with pushnotifications and it was working (on another server with a public http endpoint for exchange to call back).
I was wondering if this might have anything to do with my local machine.
How very stupid of me. I forgot to impersonate. Since I'm calling into EWS with a service account it is of course listening on the mailbox of that account unless you specify:
_service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, _primaryLabUserId);
I have the following planned architecture for my WCF client library:
using ChannelFactory instead of svcutil generated proxies because
I need more control and also I want to keep the client in a separate
assembly and avoid regenerating when my WCF service changes
need to apply a behavior with a message inspector to my WCF
endpoint, so each channel is able to send its
own authentication token
my client library will be used from a MVC front-end, so I'll have to think about possible threading issues
I'm using .NET 4.5 (maybe it has some helpers or new approaches to implement WCF clients in some better way?)
I have read many articles about various separate bits but I'm still confused about how to put it all together the right way. I have the following questions:
as I understand, it is recommended to cache ChannelFactory in a static variable and then get channels out of it, right?
is endpoint behavior specific to the entire ChannelFactory or I can apply my authentication behavior for each channel separately? If the behavior is specific to the entire factory, this means that I cannot keep any state information in my endpoint behavior objects because the same auth token will get reused for every channel, but obviously I want each channel to have its own auth token for the current user. This means, that I'll have to calculate the token inside of my endpoint behavior (I can keep it in HttpContext, and my message inspector behavior will just add it to the outgoing messages).
my client class is disposable (implements IDispose). How do I dispose the channel correctly, knowing that it might be in any possible state (not opened, opened, failed ...)? Do I just dispose it? Do I abort it and then dispose? Do I close it (but it might be not opened yet at all) and then dispose?
what do I do if I get some fault when working with the channel? Is only the channel broken or entire ChannelFactory is broken?
I guess, a line of code speaks more than a thousand words, so here is my idea in code form. I have marked all my questions above with "???" in the code.
public class MyServiceClient : IDisposable
{
// channel factory cache
private static ChannelFactory<IMyService> _factory;
private static object _lock = new object();
private IMyService _client = null;
private bool _isDisposed = false;
/// <summary>
/// Creates a channel for the service
/// </summary>
public MyServiceClient()
{
lock (_lock)
{
if (_factory == null)
{
// ... set up custom bindings here and get some config values
var endpoint = new EndpointAddress(myServiceUrl);
_factory = new ChannelFactory<IMyService>(binding, endpoint);
// ???? do I add my auth behavior for entire ChannelFactory
// or I can apply it for individual channels when I create them?
}
}
_client = _factory.CreateChannel();
}
public string MyMethod()
{
RequireClientInWorkingState();
try
{
return _client.MyMethod();
}
catch
{
RecoverFromChannelFailure();
throw;
}
}
private void RequireClientInWorkingState()
{
if (_isDisposed)
throw new InvalidOperationException("This client was disposed. Create a new one.");
// ??? is it enough to check for CommunicationState.Opened && Created?
if (state != CommunicationState.Created && state != CommunicationState.Opened)
throw new InvalidOperationException("The client channel is not ready to work. Create a new one.");
}
private void RecoverFromChannelFailure()
{
// ??? is it the best way to check if there was a problem with the channel?
if (((IChannel)_client).State != CommunicationState.Opened)
{
// ??? is it safe to call Abort? won't it throw?
((IChannel)_client).Abort();
}
// ??? and what about ChannelFactory?
// will it still be able to create channels or it also might be broken and must be thrown away?
// In that case, how do I clean up ChannelFactory correctly before creating a new one?
}
#region IDisposable
public void Dispose()
{
// ??? is it how to free the channel correctly?
// I've heard, broken channels might throw when closing
// ??? what if it is not opened yet?
// ??? what if it is in fault state?
try
{
((IChannel)_client).Close();
}
catch
{
((IChannel)_client).Abort();
}
((IDisposable)_client).Dispose();
_client = null;
_isDisposed = true;
}
#endregion
}
I guess better late then never... and looks like author has it working, this might help future WCF users.
1) ChannelFactory arranges the channel which includes all behaviors for the channel. Creating the channel via CreateChannel method "activates" the channel. Channel factories can be cached.
2) You shape the channel factory with bindings and behaviors. This shape is shared with everyone who creates this channel. As you noted in your comment you can attach message inspectors but more common case is to use Header to send custom state information to the service. You can attach headers via OperationContext.Current
using (var op = new OperationContextScope((IContextChannel)proxy))
{
var header = new MessageHeader<string>("Some State");
var hout = header.GetUntypedHeader("message", "urn:someNamespace");
OperationContext.Current.OutgoingMessageHeaders.Add(hout);
}
3) This is my general way of disposing the client channel and factory (this method is part of my ProxyBase class)
public virtual void Dispose()
{
CloseChannel();
CloseFactory();
}
protected void CloseChannel()
{
if (((IChannel)_client).State == CommunicationState.Opened)
{
try
{
((IChannel)_client).Close();
}
catch (TimeoutException /* timeout */)
{
// Handle the timeout exception
((IChannel)innerChannel).Abort();
}
catch (CommunicationException /* communicationException */)
{
// Handle the communication exception
((IChannel)_client).Abort();
}
}
}
protected void CloseFactory()
{
if (Factory.State == CommunicationState.Opened)
{
try
{
Factory.Close();
}
catch (TimeoutException /* timeout */)
{
// Handle the timeout exception
Factory.Abort();
}
catch (CommunicationException /* communicationException */)
{
// Handle the communication exception
Factory.Abort();
}
}
}
4) WCF will fault the channel not the factory. You can implement a re-connect logic but that would require that you create and derive your clients from some custom ProxyBase e.g.
protected I Channel
{
get
{
lock (_channelLock)
{
if (! object.Equals(innerChannel, default(I)))
{
ICommunicationObject channelObject = innerChannel as ICommunicationObject;
if ((channelObject.State == CommunicationState.Faulted) || (channelObject.State == CommunicationState.Closed))
{
// Channel is faulted or closing for some reason, attempt to recreate channel
innerChannel = default(I);
}
}
if (object.Equals(innerChannel, default(I)))
{
Debug.Assert(Factory != null);
innerChannel = Factory.CreateChannel();
((ICommunicationObject)innerChannel).Faulted += new EventHandler(Channel_Faulted);
}
}
return innerChannel;
}
}
5) Do not re-use channels. Open, do something, close is the normal usage pattern.
6) Create common proxy base class and derive all your clients from it. This can be helpful, like re-connecting, using pre-invoke/post invoke logic, consuming events from factory (e.g. Faulted, Opening)
7) Create your own CustomChannelFactory this gives you further control how factory behaves e.g. Set default timeouts, enforce various binding settings (MaxMessageSizes) etc.
public static void SetTimeouts(Binding binding, TimeSpan? timeout = null, TimeSpan? debugTimeout = null)
{
if (timeout == null)
{
timeout = new TimeSpan(0, 0, 1, 0);
}
if (debugTimeout == null)
{
debugTimeout = new TimeSpan(0, 0, 10, 0);
}
if (Debugger.IsAttached)
{
binding.ReceiveTimeout = debugTimeout.Value;
binding.SendTimeout = debugTimeout.Value;
}
else
{
binding.ReceiveTimeout = timeout.Value;
binding.SendTimeout = timeout.Value;
}
}
I have WCF WebService for Silverlight client.
Let's say client click "Make building".
Service will receive new task, and star counting time, until it's ready to make action (i.e add to database).
Time - how much time task will need to complete (i.e to construct building).
The point is how to delay task for the certain amount of time.
Also, is there a way to stream time from server to client ?
I have setup this:
[OperationContract]
public void GetTime()
{
foreach (IDuplexClient client in _clientDic.Values)
{
client.ShowStatus(DateTime.Now);
}
}
[OperationContract]
public void Login()
{
string clientID = OperationContext.Current.Channel.SessionId;
IDuplexClient client = OperationContext.Current.GetCallbackChannel<IDuplexClient>();
_clientDic.Add(clientID, client);
}
IDuplexClient:
[OperationContract(IsOneWay = true)]
void ShowStatus(DateTime status);
And client side:
_client.LoginAsync();
_client.GetTimeAsync();
_client.ShowStatusReceived += new EventHandler<ShowStatusReceivedEventArgs>(_client_ShowStatusReceived);
void _client_ShowStatusReceived(object sender, ShowStatusReceivedEventArgs e)
{
label1.Content = e.status.ToString();
}
It's working.. For first run. But time doesn't get refreshed, which is not what I want.
As well, after few forced refresh in browser, time stop to show at all.
public partial class MainPage : UserControl
{
Service1Client _client;
int time = 10000;
public MainPage()
{
InitializeComponent();
_client = new Service1Client(new PollingDuplexHttpBinding { DuplexMode = PollingDuplexMode.SingleMessagePerPoll, OpenTimeout = TimeSpan.FromMinutes(10), ReceiveTimeout = TimeSpan.FromMinutes(10) },
new EndpointAddress("http://localhost:44544/Service1.svc"));
_client.LoginAsync();
_client.DoWorkCompleted += new EventHandler<DoWorkCompletedEventArgs>(_client_DoWorkCompleted);
_client.DoWorkAsync();
_client.AddNewTaskAsync("testTaskzor", time);
_client.GetTimeAsync();
//_client.AddNewTaskCompleted += new EventHandler<AddNewTaskCompletedEventArgs>(_client_AddNewTaskCompleted);
_client.ShowStatusReceived += new EventHandler<ShowStatusReceivedEventArgs>(_client_ShowStatusReceived);
}
void _client_ShowStatusReceived(object sender, ShowStatusReceivedEventArgs e)
{
label1.Content = e.status.ToString();
}
void _client_DoWorkCompleted(object sender, DoWorkCompletedEventArgs e)
{
//label1.Content = e.Result;
}
}
That' entire client code.
Although I finally fixed and time is streaming properly to client (it wa surpsingly easy it was enough to enlose foreach with while(true) statment, at least for now).
But on other side. When I close browser, and open it again, nothing show up. As well as after I refresh it, time do not show up at all.
The easiest way would be to implement the delay on the client side. You can't really delay a RESTful service like WCF without breaking the model.