I am trying to write sender receiver program which will send request and wait for the reply until receiver process the request. But getting a "null" response when I call this method -convertSendAndReceive().
Well, which reply are you going to get if your "receiver is not running"?
Anyway RabbitTemplate has replyTimeout option which is:
private static final long DEFAULT_REPLY_TIMEOUT = 5000;
yeah... by default.
Related
I have Java code similar to this in a class called "MyService" to receive messages, process the object passed and return a response, with the intention to have the returned response using the configured exchange and routing key, as specified using the #SendTo annotation:
#RabbitListener(containerFactory = "myContainerFactory", queues = RabbitConfig.MY_QUEUE_NAME)
#SendTo("#{T(com.acme.config.RabbitOutboundConfig).OUTBOUND_EXCHANGE_NAME + '/' + myService.getRoutingKey()}")
public OrderResponse handlePaidOrder(Order order) {
// do processing on the input Order object here...
OrderResponse orderResponse = new OrderResponse();
// fill up response object here
return orderResponse;
}
public String getRoutingKey() {
String routingKey;
// .. custom logic to build a routing key
return routingKey;
}
This makes sense and works fine. The problem I am having is I can't figure out how to stop the "reply_to" property from coming in the message. I know if my sender configures a RabbitTemplate by calling setReplyAddress, that will result in a reply_to property and a correlation_id in the message.
However, if I simply do not call setReplyAddress, I still get a reply_to property, one that looks like this:
reply_to: amq.rabbitmq.reply-to.g2dkAAxyYWJiaXRAd3NK and so forth
and with that reply_to in the message, #SendTo has no effect. The Spring AMQP docs and this post: Dynamic SendTo annotation state:
The #SendTo is only used if there's no replyTo in the message.
Furthermore, when I don't call setReplyAddress on the RabbitTemplate, I don't get a correlation-id either. I pretty sure I am going to need that. So, my question is, how do I get my sender to generate a correlation-id but to not generate a reply-to so that my receiver can use the #SendTo annotation?
Thanks much in advance.
The correlationId is for the sender; it's not needed with direct reply-to since the channel is reserved; you could add a MessagePostProcessor on the sending side to add a correlationId.
The #SendTo is a fallback in case there is no reply_to header.
If you want to change that behavior you can add an afterReceivePostProcessor to the listener container to remove the replyTo property on the MessageProperties.
container.setAfterReceivePostProcessor(m -> {
m.getMessageProperties().setReplyTo(null);
return m;
}
Bear in mind, though, that if the sender set a replyTo, he is likely expecting a reply, so sending the reply someplace else is going to disappoint him and likely will cause some delay there until the reply times out.
If you mean you want to send an initial reply someplace else that does some more work and then finally replies to the originator, then you should save off the replyTo in another header, and reinstate it (or use an expression that references the saved-off header).
I am try to figure out if the Winsock UDP way of sending and recieving datagrams has an option to get a respond back to the sendto() like a function.
To make it clear lets say that i have a function that uses UDP to send a message
and needs to return back a true or false state
Since this function is using UDP to send a message, the application that recieves the message needs to execute a specific command and send back the returned value of true false to the UDP sender, so in that way the function from the control program will know that the function was properly executed or not.
Application 1 :
bool Test(){
functionToRun = "checkandRespond";
respond = sendto(....);
if(respond == "true"){
Brespond = true;
}else{
Brespond = false;
}
return Brespond;
}
Application 2 :
bool check(){
return true;
}
DWORD WINAPI IncomingMessages(){
recvfrom(....)
//run the function requested e.x.
bool respondto1App = check();
sendback the respondto1App boolean to string to Application 1
}
Is there any way to get back an instant respond like a function needs between two applications using UDP ?
NOTE : i don`t want to know if the sendto() command has send the message to the other application successfully, i want to get the respond back from the second application like if i was running the check() function from application 1.
Thanks in advance for any help on the issue
I am implementing a MassTransit middleware in my receive end point to record the performance of handling the message, i want to get the message type from the PipeContext, how can i get it?
public async Task Send(T context, IPipe<T> next)
{
// I want to know the message type from here so that i can log it
using (_logger.BeginTimedOperation("Time for handling message", null, LogEventLevel.Debug))
{
await next.Send(context);
}
}
You would need to intercept at the ConsumeContext, which has a property for the message types from the serialization envelope.
Then, you can get the supported message types using:
IEnumerable<string> SupportedMessageTypes {get;}
That should get you what you need to log the message type with the duration.
So a filter along the lines of:
public class LogMessageTypeFilter :
IFilter<ConsumeContext>
{
}
Implement the send method, call next within the method, and then take action after the next pipe completes.
In my test application I can see messages that were processed with an exception being automatically inserted into the default EasyNetQ_Default_Error_Queue, which is great. I can then successfully dump or requeue these messages using the Hosepipe, which also works fine, but requires dropping down to the command line and calling against both Hosepipe and the RabbitMQ API to purge the queue of retried messages.
So I'm thinking the easiest approach for my application is to simply subscribe to the error queue, so I can re-process them using the same infrastructure. But in EastNetQ, the error queue seems to be special. We need to subscribe using a proper type and routing ID, so I'm not sure what these values should be for the error queue:
bus.Subscribe<WhatShouldThisBe>("and-this", ReprocessErrorMessage);
Can I use the simple API to subscribe to the error queue, or do I need to dig into the advanced API?
If the type of my original message was TestMessage, then I'd like to be able to do something like this:
bus.Subscribe<ErrorMessage<TestMessage>>("???", ReprocessErrorMessage);
where ErrorMessage is a class provided by EasyNetQ to wrap all errors. Is this possible?
You can't use the simple API to subscribe to the error queue because it doesn't follow EasyNetQ queue type naming conventions - maybe that's something that should be fixed ;)
But the Advanced API works fine. You won't get the original message back, but it's easy to get the JSON representation which you could de-serialize yourself quite easily (using Newtonsoft.JSON). Here's an example of what your subscription code should look like:
[Test]
[Explicit("Requires a RabbitMQ server on localhost")]
public void Should_be_able_to_subscribe_to_error_messages()
{
var errorQueueName = new Conventions().ErrorQueueNamingConvention();
var queue = Queue.DeclareDurable(errorQueueName);
var autoResetEvent = new AutoResetEvent(false);
bus.Advanced.Subscribe<SystemMessages.Error>(queue, (message, info) =>
{
var error = message.Body;
Console.Out.WriteLine("error.DateTime = {0}", error.DateTime);
Console.Out.WriteLine("error.Exception = {0}", error.Exception);
Console.Out.WriteLine("error.Message = {0}", error.Message);
Console.Out.WriteLine("error.RoutingKey = {0}", error.RoutingKey);
autoResetEvent.Set();
return Task.Factory.StartNew(() => { });
});
autoResetEvent.WaitOne(1000);
}
I had to fix a small bug in the error message writing code in EasyNetQ before this worked, so please get a version >= 0.9.2.73 before trying it out. You can see the code example here
Code that works:
(I took a guess)
The screwyness with the 'foo' is because if I just pass that function HandleErrorMessage2 into the Consume call, it can't figure out that it returns a void and not a Task, so can't figure out which overload to use. (VS 2012)
Assigning to a var makes it happy.
You will want to catch the return value of the call to be able to unsubscribe by disposing the object.
Also note that Someone used a System Object name (Queue) instead of making it a EasyNetQueue or something, so you have to add the using clarification for the compiler, or fully specify it.
using Queue = EasyNetQ.Topology.Queue;
private const string QueueName = "EasyNetQ_Default_Error_Queue";
public static void Should_be_able_to_subscribe_to_error_messages(IBus bus)
{
Action <IMessage<Error>, MessageReceivedInfo> foo = HandleErrorMessage2;
IQueue queue = new Queue(QueueName,false);
bus.Advanced.Consume<Error>(queue, foo);
}
private static void HandleErrorMessage2(IMessage<Error> msg, MessageReceivedInfo info)
{
}
I am trying to understand how I would implement message framing with WCF. The goal is to create a server in WCF that can handle proprietary formats over Tcp. I can't use the net.Tcp binding because that is only for SOAP.
I need to write a custom channel that would receive messages in the following format
. An example message would be "5 abcde". In particular I am not sure how to do framing in my custom channel.
Here is some sample code
class CustomChannel: IDuplexSessionChannel
{
private class PendingRead
{
public NetworkStream Stream = null;
public byte[] Buffer = null;
public bool IsReading = false;
}
private CommunicationState state = CommunicationState.Closed;
private TcpClient tcpClient = null;
private MessageEncoder encoder = null;
private BufferManager bufferManager = null;
private TransportBindingElement bindingElement = null;
private Uri uri = null;
private PendingRead pendingRead;
public CustomChannel(Uri uri, TransportBindingElement bindingElement, MessageEncoderFactory encoderFactory, BufferManager bufferManager, TcpClient tcpClient)
{
this.uri = uri;
this.bindingElement = bindingElement;
this.tcpClient = tcpClient;
this.bufferManager = bufferManager;
state = CommunicationState.Created;
}
public IAsyncResult BeginTryReceive(TimeSpan timeout, AsyncCallback callback, object state)
{
if (this.state != CommunicationState.Opened) return null;
byte[] buffer = bufferManager.TakeBuffer(tcpClient.Available);
NetworkStream stream = tcpClient.GetStream();
pendingRead = new PendingRead { Stream = stream, Buffer = buffer, IsReading = true };
IAsyncResult result = stream.BeginRead(buffer, 0, buffer.Length, callback, state);
return result;
}
public bool EndTryReceive(IAsyncResult result, out Message message)
{
int byteCount = tcpClient.Client.EndReceive(result);
string content = Encoding.ASCII.GetString(pendingRead.buffer)
// framing logic here
Message.CreateMessage( ... )
}
}
So basically the first time around EndTryReceive could just get a piece of the message from the pending read buffer "5 ab". Then the second time around it could get the rest of the message. The problem is when EndTryReceive gets called the first time, I am forced to create a Message object, this means that there will be a partial Message going up the channel stack.
What I really want to do is to make sure that I have my full message "5 abcde" in the buffer, so that when I construct the message in EndTryReceive it is a full message.
Does anyone have any examples of how they are doing custom framing with WCF?
Thanks,
Vadim
Framing at the wire level is not something that the WCF channel model really cares about; it's pretty much up to you to handle it.
What I mean by this is that it is your responsibility to ensure that your transport channel returns "entire" messages on a receive (streaming changes that a bit, but only up to a point).
In your case, it seems you're translating receive operations on your channel directly into receive operations on the underlying socket, and that just won't do, because that won't give you a chance to enforce your own framing rules.
So really, a single receive operation on your channel might very well translate to more than one receive operation on the underlying socket, and that's fine (and you can still do all that async, so it doesn't need to affect that part).
So basically the question becomes: what's your protocol framing model look like? Wild guess here, but it looks like messages are length prefixed, with the length encoded as a decimal string? (looks annoying).
I think your best bet in that case would be to have your transport buffer incoming data (say, up to 64KB of data or whatever), and then on each receive operation check the buffer to see if it contains enough bytes to extract the length of the incoming message. If so, then either read as many bytes as necessary from the buffer, or flush the buffer and read as many bytes from the socket. You'll have to be careful as, depending on how your protocol works, I'm assuming you might end up reading partial messages before you actually need them.
I agree with the thomasr. You can find some basic inspiration in Microsoft Technology Sample "ChunkingChannel".