I have a Spring Boot app, where I receive one single message from a Azure Service Bus queue session.
The code is:
#Autowired
ServiceBusSessionReceiverAsyncClient apiMessageQueueIntegrator;
.
.
.
Mono<ServiceBusReceiverAsyncClient> receiverMono = apiMessageQueueIntegrator.acceptSession(sessionid);
Disposable subscription = Flux.usingWhen(receiverMono,
receiver -> receiver.receiveMessages(),
receiver -> Mono.fromRunnable(() -> receiver.close()))
.subscribe(message -> {
// Process message.
logger.info(String.format("Message received from quque. Session id: %s. Contents: %s%n", message.getSessionId(),
message.getBody()));
receivedMessage.setReceivedMessage(message);
timeoutCheck.countDown();
}, error -> {
logger.info("Queue error occurred: " + error);
});
As I am receiving only one message from the session, I use a CountDownLatch(1) to dispose of the subscription when I have received the message.
The documentation of the library says that it is possible to use Mono.usingWhen instead of Flux.usingWhen if I only expect one message, but I cannot find any examples of this anywhere, and I have not been able to figure out how to rewrite this code to do this.
How would the pasted code look if I were to use Mono.usingWhen instead?
Thank you conniey. Posting your suggestion as an answer to help other community members.
By default receiveMessages() is a Flux because we imagine the messages from a session to be "infinitely long". In your case, you only want the first message in the stream, so we use the next() operator.
The usage of the countdown latch is probably not the best approach. In the sample, we had one there so that the program didn't end before the messages were received. .subscribe is not a blocking call, it sets up the handlers and moves onto the next line of code.
Mono<ServiceBusReceiverAsyncClient> receiverMono = sessionReceiver.acceptSession("greetings-id");
Mono<ServiceBusReceivedMessage> singleMessageMono = Mono.usingWhen(receiverMono,
receiver -> {
// Anything you wish to do with the receiver.
// In this case we only want to take the first message, so we use the "next" operator. This returns a
// Mono.
return receiver.receiveMessages().next();
},
receiver -> Mono.fromRunnable(() -> receiver.close()));
try {
// Turns this into a blocking call. .block() waits indefinitely, so we have a timeout.
ServiceBusReceivedMessage message = singleMessageMono.block(Duration.ofSeconds(30));
if (message != null) {
// Process message.
}
} catch (Exception error) {
System.err.println("Error occurred: " + error);
}
You can refer to GitHub issue:ServiceBusSessionReceiverAsyncClient - Mono instead of Flux
Related
I have what it thought would be a simple statestore use case. We loop through a state store every 10s and try to send to a partner, if we receive 404, we try again next intervall.
If we receive 200, we delete the entry from the state store.
In my test (1 entry in statestore) I first let it run a few loops, where we receive 404, just to test that the retry works. When I switch my mock endpoint to return 200, I can see through the logs that both:
stateStore.delete(key) and stateStore.flush() is called. I even confirm after stateStore.delete(key) that stateStore.get(key) returns a null value (tombstone).
However, the next time the punctuator runs (10s), the object is still in the state store and the entire block is called again. it keeps looping like this, without ever deleting the entry in the statestore
#Override
public void punctuate(long l) {
log.info("PeriodicRetryPunctuator started: " + l);
try(KeyValueIterator<String, TestEventObject> iter = stateStore.all()) {
while(iter.hasNext()) {
KeyValue<String, TestEventObject> keyValue = iter.next();
String key = keyValue.key;
TestEventObject event = keyValue.value;
try {
log.info("Event: " + event);
// Sends event over HTTP. Will throw HttpResponseException if 404 is received
eventService.processEvent(event);
stateStore.delete(key);
stateStore.flush();
// Check that statestore returns null
log.info("Check: " + stateStore.get(key));
} catch (HttpResponseException hre) {
log.info("Periodic retry received 404. Retrying at next interval");
}
catch (Exception e) {
e.printStackTrace();
log.error("Exception with periodic retry: {}", e.getMessage());
}
}
}
}
Update:
It seems to be Confluent's encryption libraries that causes these issues. I've done quite an extensive A/B test, and every time it occurs is with Confluent encryption. Without I never experience this issue.
I'm writing code in java (using Azure SDK for Java), I have a Service bus queue that contains sessionful messages. I want to receive those messages and process them to another place.
I make a connection to the Queue by using QueueClient, and then I use registerSessionHandler to process through the messages (code below).
The problem is that whenever a message is received, I can print all details about it including the content, but it is printed 10 times and after each time it prints an Exception.
(printing 10 times: I understand that this is because there is a 10 times retry policy before it throws the message to the Dead letter queue and goes to the next message.)
The Exception says
> USERCALLBACK-Receiver not created. Registering a MessageHandler creates a receiver.
The output with the Exception
But I'm sure that the SessionHandler does the same thing as MessageHandler but includes support for sessions, so it should create a receiver since it receives messages. I have tried to use MessageHandler but it won't even work and stops the whole program because it doesn't support sessionful messages, and the ones I receive have sessions.
My problem is understanding what the Exception wants me to do, and how can I fix the code so it won't give me any exceptions? Does anyone have suggestions on how to improve the code? or other methods that do the same thing?
QueueClient qc = new QueueClient(
new ConnectionStringBuilder(connectionString),
ReceiveMode.PEEKLOCK);
qc.registerSessionHandler(
new ISessionHandler() {
#Override
public CompletableFuture<Void> onMessageAsync(IMessageSession messageSession, IMessage message) {
System.out.printf(
"\nMessage received: " +
"\n --> MessageId = %s " +
"\n --> SessionId = %s" +
"\n --> Content Type = %s" +
"\n --> Content = \n\t\t %s",
message.getMessageId(),
messageSession.getSessionId(),
message.getContentType(),
getMessageContent(message)
);
return qc.completeAsync(message.getLockToken());
}
#Override
public CompletableFuture<Void> OnCloseSessionAsync(IMessageSession iMessageSession) {
return CompletableFuture.completedFuture(null);
}
#Override
public void notifyException(Throwable throwable, ExceptionPhase exceptionPhase) {
System.out.println("\n Exception " + exceptionPhase + "-" + throwable.getMessage());
}
},
new SessionHandlerOptions(1, true, Duration.ofMinutes(1)),
Executors.newSingleThreadExecutor()
);
(The getMessageContent(message) method is a separate method, for those interested:)
public String getMessageContent(IMessage message){
List<byte[]> content = message.getMessageBody().getBinaryData();
StringBuilder sb = new StringBuilder();
for (byte[] b : content) {
sb.append(new String(b)
);
}
return sb.toString();
}
For those who wonder, I managed to solve the problem!
It was simply done by using Azure Functions ServiceBusQueueTrigger, it will then listen to the Service bus Queue and process the messages. By setting isSessionsEnabled to true, it will accept sessionful messages as I wanted :)
So instead of writing more than 100 lines of code, the code looks like this now:
public class Function {
#FunctionName("QueueFunction")
public void run(
#ServiceBusQueueTrigger(
name = "TriggerName", //Any name you choose
queueName = "queueName", //QueueName from the portal
connection = "ConnectionString", //ConnectionString from the portal
isSessionsEnabled = true
) String message,
ExecutionContext context
) {
// Write the code you want to do with the message here
// Using the variable messsage which contains the messageContent, messageId, sessionId etc.
}
}
I have following flow:
return flow -> flow.channel(inputChannel())
...
.gateway(childFlow, addMyInterceptor(str)); // by name
}
Consumer<GatewayEndpointSpec> addMyInterceptor(String objectIdHeader) {
return endpointSpec -> endpointSpec.advice(addMyInterceptorInternal(objectIdHeader))
.errorChannel(errorChannel());
}
default IdempotentReceiverInterceptor addMyInterceptorInternal(String header) {
MessageProcessor<String> headerSelector = message -> headerExpression(header).apply(message);
var interceptor = new IdempotentReceiverInterceptor(new MetadataStoreSelector(headerSelector, idempotencyStore()));
interceptor.setDiscardChannel(idempotentDiscardChannel());
return interceptor;
}
When IdempotentReceiverInterceptor encounters that message is duplicated - I see that application hangs on after 4-th duplicated message. I understand that it is because gateway expected response(like here: PubSubInboundChannelAdapter stops to receive messages after 4th message) but I don't have any ideas how to return result from interceptor.
Could you please explain it for me?
As long as all channels are direct (default) - i.e. no async handoffs in the flow using queue or executor channels, set the gateway's replyTimeout to 0 when the flow might not return a reply
I have have a message producer on my local machine and a broker on remote host (aws).
After sending a message from the producer,
I wait and call the console consumer on the remote host and
see excessive logs.
Without the value from producer.
The producer flushes the data after calling the send method.
Everything is configured correctly.
How can I check to see that the broker received the message from the producer and to see if the producer received the answer?
The Send method asynchronously sends the message to the topic and
returns a Future of RecordMetadata.
java.util.concurrent.Future<RecordMetadata> send(ProducerRecord<K,V> record)
Asynchronously sends a record to a topic
After the flush call,
check to see that the Future has completed by calling the isDone method.
(for example, Future.isDone() == true)
Invoking this method makes all buffered records immediately available to send (even if linger.ms is greater than 0) and blocks on the completion of the requests associated with these records. The post-condition of flush() is that any previously sent record will have completed (e.g. Future.isDone() == true). A request is considered completed when it is successfully acknowledged according to the acks configuration you have specified or else it results in an error.
The RecordMetadata contains the offset and the partition
public int partition()
The partition the record was sent to
public long offset()
the offset of the record, or -1 if {hasOffset()} returns false.
Or you can also use Callback function to ensure messages was sent to topic or not
Fully non-blocking usage can make use of the Callback parameter to provide a callback that will be invoked when the request is complete.
here is clear example in docs
ProducerRecord<byte[],byte[]> record = new ProducerRecord<byte[],byte[]>("the-topic", key, value);
producer.send(myRecord,
new Callback() {
public void onCompletion(RecordMetadata metadata, Exception e) {
if(e != null) {
e.printStackTrace();
} else {
System.out.println("The offset of the record we just sent is: " + metadata.offset());
}
}
});
You can try get() API of send , which will return the Future of RecordMetadata
ProducerRecord<String, String> record =
new ProducerRecord<>("SampleTopic", "SampleKey", "SampleValue");
try {
producer.send(record).get();
} catch (Exception e) {
e.printStackTrace();
}
Use exactly-once-delivery and you won't need to worry about whether your message reached or not: https://www.baeldung.com/kafka-exactly-once, https://www.confluent.io/blog/exactly-once-semantics-are-possible-heres-how-apache-kafka-does-it/
I've encounter the problem that if my method below fails or it's an exception I still consume the msg. I would want the functionality to do a rollback during the catch and place the msg back on the queue/topic.
public void onMessage(Message message)
{
String messageId = null;
Date messagePublished = null;
try
{
messageId = message.getJMSMessageID();
messagePublished = new Date(message.getJMSTimestamp());
LOGGER.info("JMS Message id =" + messageId + " JMS Timestamp= " + messagePublished);
process(message);
LOGGER.info(" returning from onMessage() successfully =" + messageId + " JMS Timestamp= " + messagePublished);
}
catch(Throwable t)
{
LOGGER.error("Exception:",t);
LOGGER.error(t.getStackTrace() + "\n Exception is unrecoverable.");
throw new RuntimeException("Failed to handle message.",t);
}
}
You can look at the different acknowledge modes that exist within JMS for this. See this article http://www.javaworld.com/javaworld/jw-02-2002/jw-0315-jms.html.
The appropriate mode for you would be Client mode.
So basically, the client needs to acknowledge when they are happy they have processed the message.
You could call the acknowledge after the call to process(message), if an exception occurs in the proccess(message) method, the message will not have been dequeued as you didnt acknowledge it. We used this approach before with Oracle AQ and it works very well.
This approach means you dont have to worry about transactions for the messages on the queue (Database transactions are another story). The only thing you need to ensure is that your app can handle a call to process(message) with potential duplicate messages
you should be able to just make your onMessage method transacted.