Apache Kafka® Consumer Example using SpringBoot 3 | Consumer Groups | Java Techie

In this tutorial, we will be creating a simple Kafka consumer using Spring Boot 3.0 and will understand below key points
👉 How to consume events from topic
👉 How kafka makes partition and consumer mapping
👉 Offset Explorer to visualize kafka events and lags
#JavaTechie #SpringBoot #Kafka
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[@satyabatigoswami1735]

Got to understand kafka by following your tutorials. So clear explanation!! You are great😇

[@amankumar-f4n5r]

just started watching your video of kafka today at 10 am morning. I couldn't stop myself and its 2 am next day just completed your all videos of kafka with hands on. Just one suggestions keep your kafka consumer topic in kafka playlist otherwise many can miss tracking this .Also i'm waiting for other kafka topics like kafka connect with database where messages are being received from different source system which kafka server listen and stores those in our database and vice versa

[@Javatechie]

Waoo super excitement.thanks buddy i will definitely cover all concepts of Kafka

[@SivaChaitanyaReddySanivarapu]

Great topic, we are using this in my billing project

[@AleksandarT10]

Great video! Explains how Kafka Consumers work pretty clearly. As an idea for the next video/s, you can go over more of the properties of Kafka for Producers/Consumers - and explain concepts like batching, the most common properties that can be configured (like manual acknowledgement or not) etc

[@Javatechie]

Thanks for the tips! That's what's on my queue 🤪

[@dileepkumarsattaru1909]

Nice Basant, Keep going with this series...

[@ravi.m4954]

Nice explanation. Can you cover in upcoming videos like how can we replay or retry lagged messages and how to identify which messages lagged and how to replay those .

[@Javatechie]

Yes i will cover that

[@shubhammotghare783]

Hey, 1st of all thank you for the great tutorial. I've one question. When you change the group-id in service class, is it not mandatory to change or add that new group-id in application.yml ?

[@vaishalis]

Hi Basant, thank you for an excellent informative video. What I do not understand about the lag is, if Kafka stores the messages for minimum one week, then why do we have to republish the messages which are in the lag. Why it will not automatically be reprocessed when the consumer is back up and running?

[@Javatechie]

It will automatically be consumed by the consumer once it goes back to online. But republish required when you want to resend a particular events

[@GunelMammadova93]

Thanks for the amazing tutorial!

[@BhanuNandanaPavanKumarBavirise]

How to write consumer instances dynamically in a single method...for every consumer instance you have created one method but only one method should multiple consumer instances naa?

[@gauravsrivastava3884]

Hi Basant !! Can you please all the necessary videos of this particular Kafka series to a KZbin Playlist. It will make it easy to access all relevant videos from one place. And as and when you create new videos, you can add them to the playlist. Thanks!

[@Javatechie]

Hi buddy it’s already there in Kafka for beginners playlist please check

[@gauravsrivastava3884]

Got it. Thanks!!

[@SandeepPuvvada-u5p]

Good Explanation basant. Great work. I have one quick question you change the group id in the java class but not changed in yml still application works fine. Then what is the point of adding the group id in yml.

[@Javatechie]

Either or you can add buddy. I forgot to mention that in video

[@ankurverma4592]

awesome explanation able to learn the whole very well. Thank you

[@mohammedsardar3779]

Mesage consumption is decided by leader broker and not by the zookeeper. Zukeeper will be keeping the status of brokers and act as coordinator for all the brokers. Am I wrong Basant?

[@Javatechie]

No you are correct

[@LearncodewithMuneeb]

Thanks sir for making useful videos for us. But I request you very respectfully to work in a project in spring boot having at least 6 entities/tables using spring boot in the back end and React/Angular/Next in the front end

[@Зебратв-п7э]

thank you for your tutuorial easy to understand but i have question is it possible to miss data in kafka between producer and consumer process if it likes that how can i avoid missing data

[@Javatechie]

We need to implement a retry i will cover that

[@RochaNahuel]

The example is clear and I like it , but these 3 consumers who are listening to the same topic and working together , could call the same method of the logica layer without problems ?

[@Javatechie]

Yes no problem at all because message will not be duplicate

[@amankumar-f4n5r]

you are awesome Basant

[@appstude6247]

thank you for the video. can please tell me what's will happen if you start kafka-consumer-example project twice ? how many consumer will have ? 3 consumer in each instance ?

[@maximilian_gl]

Very nice and helpful!

[@Javatechie]

Glad it was helpful!

[@VIKASSINGH-jf6jd]

Basant. How do you create this beautiful presentation ? Which tool do you use or animation ?

[@Javatechie]

No animation buddy it's simple Microsoft power point

[@raghugattu296]

Hi, Instead of creating new consumer groups, can we not increase threads count to 3 in one method using thread property?

[@Javatechie]

I will cover that content buddy

[@geekdeb5363]

Great , If you can enlighten on the real time project prospective, it would be great

[@Javatechie]

I will do one e2e project using microservice that time will cover that scenario

[@geekdeb5363]

@@Javatechie Thank you 😊

[@Gsuresh_3]

Hello, Recently I faced a question in interview, if I give a java project along with remote server without any IDE how you run that project. Can you make a video on it

[@dhamodharankrishnamoorthi1921]

How i can create multiple consumer group, and consume message concurrent please explain

[@RaviKumar-v9b6m]

Hi can you create videos on Kafka stream?

[@Chinmay0692010]

If consumers get shut down while consuming, so if we start again the consumers , will it not take those messages which was not consumed….?

[@Javatechie]

Yes he will start picking based on what last offset he read before

[@entertainer-xyz7562]

Hi Basant , I was going through this Kafka tutorial, I got a question on groupid that you have assigned to multiple consumers. My question is can we provide different groupid to different consumers?

[@Javatechie]

Yes we can I just defined it to same consumer to just demonstrate partition and consumer relationship

[@sharmarahul17]

Excellent video!

[@royjose.]

once the consumer is enabled again, will the lag values reach the consumer automatically?

[@Javatechie]

Yes it will process automatically once consumer back to online

[@ramsharan4229]

awesome

[@pnamm6501]

Great video. Can you cover avro schema and retry mechanism and also how handle any exception when processing message consumption?

[@Javatechie]

I will do that exception handling

[@SystemDesign-fn9zu]

Thanks

[@Javatechie]

Thank you buddy 😊

[@saurabhmaurya6964]

how can we fetch all the messages from the particular topic after hitting end-point url ?..Help me with this..I tried To do with the help of KafkaConsumer consumer .. this has a method poll .. but after hitting end point i'm getting null in consumer..please help me with this ..

[@Javatechie]

What field you are getting null ?

[@saurabhmaurya6964]

@@Javatechie in the consumer.poll section..can we connect seperately on meet so I can show you there?..

[@Javatechie]

@@saurabhmaurya6964 sure please drop me an email to [e-mail]

[@kartikjain3064]

Hi, so we no need of define ProducerFactory, ConsumerFactory in our code

[@Javatechie]

That will be my next video don't worry

[@NareshSilpa-o1h]

Hi brother, Good Evening, i would like to join your - Spring boot & Micro service sessions. so Kindly guide me on that, How to register and talk to you. Thanks!

[@Javatechie]

Hello buddy please checkout any video description I have shared the course link and coupon code for course but still if you are getting confused then please refer to this video kzbin.info/www/bejne/bmWui5Rqmat_itE

[@siddharthanepal1962]

Hi can you make video for how kafka handle duplicates events or messages. What if producer send same events/message twice and how consumer will acknowledge the duplicates?

[@Javatechie]

Okay sure i will do that

[@rakushhkar4225]

How does your Producer send messages in the Queue is most important. If you send messages in a sequential way using some ID like OrderId then the message content may be duplicated but atleast the order is not. Resending messages is required if original previous message were not processed properly. There is Transaction API that supports Once Processing. Alternative is to have a Dedupe check on Consumer. But why are you insisting on non to allow duplicate messages is to be answered by you.

[@siddharthanepal1962]

@rakushhkar4225 Recently, in an interview, I got this question. The interviewer asked me what happens when an exception occurs during message processing on the consumer side. How will the consumer process the failed messages? I am a beginner with kafka. If you have some videos tutorial or sameple codes, please suggest.

[@rakushhkar4225]

@@siddharthanepal1962 Also better get RabbitMQ installed to see the console where all messages are processed and stored and the parameter D is very important. Work on Stream and Quorum messages in detail too along with Classic type

[@mohammedsardar3779]

There is an Idempotency property along with producer that helps here to avoid duplicates message process. Just shared a point of knowledge. If this is enabled broker will ignore the repetative message for uniqueness.

[@pavanreddy3162]

how long the messages are store in kafka?

[@hanumanthram6754]

If the consumer is stopped then it should continue to consume the data based on the offset. is that correct understanding?

[@Javatechie]

No if the consumer is shut down then what to consume and who will consume buddy?

[@hanumanthram6754]

@@Javatechie I mean if that consumer stopped nd again restarted that consumer will continue to consume the data based on offset. Is that not possible. Like in real-time producer produced data and stored in topic and consumer should consume data and put that in database if consumer server stopped in the middle and again again restarted can't that consumer group continue to consume the data based on offset? It is my question

[@hanumanthram6754]

Offset Management: 1. Kafka maintains the offset for each consumer group. When a consumer reads messages from a topic, it keeps track of the offset of the last message it has processed for each partition. The offset is stored in a Kafka topic called __consumer_offsets. Kafka brokers manage the offset commits and offsets are periodically committed by the consumer group coordinator. Consumer Restart Behavior: 2. When a consumer is stopped or goes down, the next time it restarts, it will retrieve its last committed offset for each partition from the __consumer_offsets topic. Upon restarting, the consumer will begin to consume messages from the topics starting at the last committed offset for each partition. This ensures that the consumer continues from where it left off, processing messages that were not yet consumed before the shutdown

[@rahulprakash5045]

is it required to add consumer group ?

[@Javatechie]

Yes it's mandatory steps to do

[@rishiraj2548]

🙏💯

[@ReplayButton_7518]

It is not working for me can , the message producer worked fine but I got nothing on message consumer

[@CharanSaiAnnam]

Share your repository we will debug

[@PradeepKumar-sx6ms]

Are any videos on kafka coming?

[@Javatechie]

Yes error handling and retry

[@saurabhsuradkar1626]

consumer is not able to receive msg or connect to broker

[@saravanakumars52]

What about @EnableKafka annotation??

[@Javatechie]

Not mandatory

[@Derrick-f8m]

The GOAT

[@Javatechie]

What?

[@rajenderprasad1193]

It means Greatest Of All Time- shortly GOAT

[@arunprabu6137]

Bro how to connect offset kafka

[@VINOTHCH]

@javatechie i need your help to complete a work. it is very urgent i'm subscribing a topic and i need to interpret the topic message and save it dynamodb

[@Javatechie]

Are you using SQS ?

[@VINOTHCH]

@@Javatechie I’m using Kafka

[@aces8481]

bro zoom in lol the text is tiny at times