I am building a Springboot application using Spring Kafka where I am getting messages from a topic. I have to modify those messages and then produce them to another topic. I don't want to consume any other message till I have processed my current one. How can I achieve this?
#KafkaListener(
topics = "${event.topic.name}",
groupId = "${event.topic.group.id}",
containerFactory = "eventKafkaListenerContainerFactory"
)
public void consume(Event event) {
logger.info(String.format("Event created(from consumer)-> %s", event));
}
"event" is a json object which I am receiving as a message.
See https://docs.confluent.io/platform/current/installation/configuration/consumer-configs.html#consumerconfigs_max.poll.records:
max.poll.records
The maximum number of records returned in a single call to poll().
Type: int
Default: 500
With Spring Boot you can configure it as this property:
spring.kafka.consumer.maxPollRecords
So, you set it to 1 and no more records are going to be polled from this consumer until you return from your #KafkaListener method.
Related
I have an listener which is listening for UDP packets and after receiving and processing that data want to stream it to a topic (currently Kafka).
I have managed to run a sample program of Spring Cloud Stream Kafka Binder producer.
#Bean
public Supplier<PacketDataPojo> data() {
return () -> {
PacketDataPojo pdp = new PacketDataPojo(UUID.randomUUID().toString());
log.info("Current data {}", pdp);
return pdp;
};
}
application.properties
spring.cloud.function.definition=data
spring.cloud.stream.bindings.data-out-0.destination=data-stream
Now as it is generating data with some scheduled interval, how can I make Supplier to stream data after packet processing is completed.
Thanks
I believe the StreamBridge will do the trick for you - https://docs.spring.io/spring-cloud-stream/docs/3.1.5/reference/html/spring-cloud-stream.html#_sending_arbitrary_data_to_an_output_e_g_foreign_event_driven_sources
So, you may not need Supplier for your case
I have requirement where need to have a Spring Boot Rest Service that a client application will call every 30 minutes and service is to return
number of latest messages based on the number specified in query param e.g. http://messages.com/getNewMessages?number=10 in this case should return 10 messages
number of messages based on the number and offset specified in query param e.g. http://messages.com/getSpecificMessages?number=5&start=123 in this case should return 5 messages starting offset 123.
I have simple standalone application and it works fine. Here is what I tested and would lke some direction of incorporating it in the service.
public static void main(String[] args) {
// create kafka consumer
Properties properties = new Properties();
properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
properties.put(ConsumerConfig.GROUP_ID_CONFIG, "my-first-consumer-group");
properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
properties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
properties.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, false);
properties.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG, args[0]);
Consumer<String, String> consumer = new KafkaConsumer<>(properties);
// subscribe to topic
consumer.subscribe(Collections.singleton("test"));
consumer.poll(0);
//get to specific offset and get specified number of messages
for (TopicPartition partition : consumer.assignment())
consumer.seek(partition, args[1]);
ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(5000));
System.out.println("Total Record Count ******* : " + records.count());
for (ConsumerRecord<String, String> record : records) {
System.out.println("Message: " + record.value());
System.out.println("Message offset: " + record.offset());
System.out.println("Message: " + record.timestamp());
Date date = new Date(record.timestamp());
Format format = new SimpleDateFormat("yyyy MM dd HH:mm:ss.SSS");
System.out.println("Message date: " + format.format(date));
}
consumer.commitSync();
As my consumer will be on-demand wondering in Spring Boot Service how I can achieve this. Where do I specify the properties if I put in application.properties those get's injected at startup time but how do i control MAX_POLL_RECORDS_CONFIG at runtime. Any help appreciated.
MAX_POLL_RECORDS_CONFIG only impact your kafka-client return the records to your spring service, it will never reduce the bytes that the consumer poll from kafka-server
see the above picture, no matter your start offset = 150 or 190, kafka server will return the whole data from (offset=110, offset=190), kafka server even didn't know how many records return to consumer, he only know the byte size = (220 - 110)
so i think you can control the record number by yourself,currently it is controlled by the kafka client jar, they are both occupy your jvm local memory
The answer to your question is here and the answer with code example is this answer.
Both written by the excellent Gary Russell, the main or one of the main person behind Spring Kafka.
TL;DR:
If you want to arbitrarily rewind the partitions at runtime, have your
listener implement ConsumerSeekAware and grab a reference to the
ConsumerSeekCallback.
i define a queue channel
#Bean("mail-action-laundry-list-channel")
public MessageChannel mailRecipientActionMessageChannel() {
return new QueueChannel(20);
}
the flow below, i will aggrate messages from the queue channel, i tried this:
#Bean
public IntegrationFlow mailRecipientActionLaundryListMessageFlow(#Qualifier("laundryListMessageHandler") MessageHandler laundryListMessageHandler) {
return IntegrationFlows.from("mail-action-laundry-list-channel")
.log("--> laundry list messages:：")
.aggregate(aggregatorSpec -> aggregatorSpec
.correlationExpression("#this.payload.email")
.releaseExpression("#this.size() == 5")
.messageStore(new SimpleMessageStore(100))
.groupTimeout(2000))
.transform(laundryListMessageToItemProcessDtoTransformer())
.handle(laundryListMessageHandler)
.get();
}
but why it aggrate first 5 messages from the channel always, and aggrate other message no longer
You need to configure expireGroupsUponCompletion(true) on the aggregator:
When set to true (default false), completed groups are removed from the message store, allowing subsequent messages with the same correlation to form a new group. The default behavior is to send messages with the same correlation as a completed group to the discard-channel.
Looks like your subsequent messages from the queue has the same email property. Therefore an aggregator can't form a new group for the same correlation key.
https://docs.spring.io/spring-integration/docs/5.0.3.RELEASE/reference/html/messaging-routing-chapter.html#aggregator-config
I have some Java code that reads messages from an ActiveMQ queue. The code uses a JmsTemplate from Spring and I use the "browseSelected" method to retrieve any messages from the queue that have a timestamp in their header older than 7 days (by creating the appropriate criteria as part of the messageSelector parameter).
myJmsTemplate.browseSelected(myQueue, myCriteria, new BrowserCallback<Integer>() {
#Override
public Integer doInJms(Session s, QueueBrowser qb) throws JMSException {
#SuppressWarnings("unchecked")
final Enumeration<Message> e = qb.getEnumeration();
int count = 0;
while (e.hasMoreElements()) {
final Message m = e.nextElement();
final TextMessage tm = (TextMessage) MyClass.this.jmsQueueTemplate.receiveSelected(
MyClass.this.myQueue, "JMSMessageID = '" + m.getJMSMessageID() + "'");
myMessages.add(tm);
count++;
}
return count;
}
});
The BrowserCallback's "doInJms" method adds the messages which match the criteria to a list ("myMessages") which subsequently get processed further.
The issue is that I'm finding the code will only process 400 messages each time it runs, even though there are several thousand messages which match the criteria specified.
When I previously used another queueing technology with this code (IBM MQ), it would process all records which met the criteria.
I'm wondering whether I'm experiencing an issue with ActiveMQ's prefetch limit: http://activemq.apache.org/what-is-the-prefetch-limit-for.html
Versions: ActiveMQ 5.10.1 and Spring 3.2.2.
Thanks in advance for any assistance.
The broker will only return up to 400 message by default as configured by the maxBrowsePageSize option in the destination policies. You can increase that value but must use caution as the messages are paged into memory and as such can lead you into an OOM situation.
You must always remember that a message broker is not a database, using it as one will generally end in tears.
everyone. I have an HTTP API for posting messages in a RabbitMQ broker and I need to implement the request-response pattern in order to receive the responses from the server. So I am something like a bridge between the clients and the server. I push the messages to the broker with specific routing-key and there is a Consumer for that messages, which is publishing back massages as response and my API must consume the response for every request. So the diagram is something like this:
So what I do is the following- For every HTTP session I create a temporary responseQueue(which is bound to the default exchange, with routing key the name of that queue), after that I set the replyTo header of the message to be the name of the response queue(where I will wait for the response) and also set the template replyQueue to that queue. Here is my code:
public void sendMessage(AbstractEvent objectToSend, final String routingKey) {
final Queue responseQueue = rabbitAdmin.declareQueue();
byte[] messageAsBytes = null;
try {
messageAsBytes = new ObjectMapper().writeValueAsBytes(objectToSend);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
MessageProperties properties = new MessageProperties();
properties.setHeader("ContentType", MessageBodyFormat.JSON);
properties.setReplyTo(responseQueue.getName());
requestTemplate.setReplyQueue(responseQueue);
Message message = new Message(messageAsBytes, properties);
Message receivedMessage = (Message)requestTemplate.convertSendAndReceive(routingKey, message);
}
So what is the problem: The message is sent, after that it is consumed by the Consumer and its response is correctly sent to the right queue, but for some reason it is not taken back in the convertSendAndReceived method and after the set timeout my receivedMessage is null. So I tried to do several things- I started to inspect the spring code(by the way it's a real nightmare to do that) and saw that is I don't declare the response queue it creates a temporal for me, and the replyTo header is set to the name of the queue(the same what I do). The result was the same- the receivedMessage is still null. After that I decided to use another template which uses the default exchange, because the responseQueue is bound to that exchange:
requestTemplate.send(routingKey, message);
Message receivedMessage = receivingTemplate.receive(responseQueue.getName());
The result was the same- the responseMessage is still null.
The versions of the amqp and rabbit are respectively 1.2.1 and 1.2.0. So I am sure that I miss something, but I don't know what is it, so if someone can help me I would be extremely grateful.
1> It's strange that RabbitTemplate uses doSendAndReceiveWithFixed if you provide the requestTemplate.setReplyQueue(responseQueue). Looks like it is false in your explanation.
2> To make it worked with fixed ReplyQueue you should configure a reply ListenerContainer:
SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
container.setConnectionFactory(rabbitConnectionFactory);
container.setQueues(responseQueue);
container.setMessageListener(requestTemplate);
3> But the most important part here is around correlation. The RabbitTemplate.sendAndReceive populates correlationId message property, but the consumer side has to get deal with it, too: it's not enough just to send reply to the responseQueue, the reply message should has the same correlationId property. See here: how to send response from consumer to producer to the particular request using Spring AMQP?
BTW there is no reason to populate the Message manually: You can just simply support Jackson2JsonMessageConverter to the RabbitTemplate and it will convert your objectToSend to the JSON bytes automatically with appropriate headers.