First message (produce and consume) in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to produce a message to the Kafka topic.

Kafka

producer.send('[1]', b'Hello Kafka!')

Drag options to blanks, or click blank then click option'

Amessages

Bmy_topic

Ckafka_topic

Dtopic1

Attempts:

3 left

💡 Hint

Common Mistakes

Using a topic name that is not defined or different from the example.

Forgetting to put the topic name as a string.

The code sends a message to the Kafka topic named 'topic1'.

2fill in blank

medium

Complete the code to consume a message from the Kafka topic.

Kafka

for message in consumer.[1]():
    print(message.value.decode('utf-8'))

Drag options to blanks, or click blank then click option'

Aconsume

Bpoll

Csubscribe

Dpoll_messages

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'subscribe' instead of 'consume' to get messages.

Using a method that does not exist on the consumer object.

The consumer uses the consume() method to get messages from the topic.

3fill in blank

hard

Fix the error in the code to produce a message with the correct key.

Kafka

producer.send('topic1', key=[1], value=b'Hello')

Drag options to blanks, or click blank then click option'

A'key1'

Bb'key1'

Ckey1

D123

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string without b prefix for the key.

Using a variable name without quotes or bytes.

The key must be bytes, so b'key1' is correct.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps message keys to values.

Kafka

messages = {msg.[1]: msg.[2] for msg in consumer.consume()}

Drag options to blanks, or click blank then click option'

Akey

Bvalue

Ctopic

Dpartition

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'topic' or 'partition' instead of 'key' or 'value'.

Mixing up key and value positions.

Each message's key and value are accessed by msg.key and msg.value.

5fill in blank

hard

Fill all three blanks to produce and flush a message to the topic with a key and value.

Kafka

producer.send('[1]', key=[2], value=[3])
producer.flush()

Drag options to blanks, or click blank then click option'

Atopic1

Bb'key123'

Cb'Hello Kafka!'

Db'value'

Attempts:

3 left

💡 Hint

Common Mistakes

Using strings instead of bytes for key or value.

Forgetting to flush after sending.

The message is sent to 'topic1' with key b'key123' and value b'Hello Kafka!'.

Practice

1. What is the main purpose of producing a message in Kafka?

easy

A. To send data to a Kafka topic

B. To read data from a Kafka topic

C. To delete messages from a Kafka topic

D. To create a new Kafka topic

Solution

1. Step 1: Understand Kafka producing

   Producing means sending messages to a Kafka topic as bytes.

2. Step 2: Differentiate producing from consuming

   Consuming reads messages, but producing sends them.

3. Final Answer:

   To send data to a Kafka topic -> Option A

4. Quick Check:

   Producing = Sending messages [OK]

Hint: Producing means sending messages to Kafka topics [OK]

Common Mistakes:

• Confusing producing with consuming
• Thinking producing deletes messages
• Assuming producing creates topics

2. Which of the following is the correct way to create a Kafka producer in Python using the kafka-python library?

easy

A. producer = KafkaConsumer(topic='mytopic')

B. producer = KafkaConsumer(bootstrap_servers='localhost:9092')

C. producer = KafkaProducer(topic='mytopic')

D. producer = KafkaProducer(bootstrap_servers='localhost:9092')

Solution

1. Step 1: Identify Kafka producer creation syntax

   KafkaProducer is created with bootstrap_servers parameter specifying Kafka server address.

2. Step 2: Eliminate consumer and wrong parameters

   KafkaConsumer is for consuming, not producing. Topic is not a parameter for producer creation.

3. Final Answer:

   producer = KafkaProducer(bootstrap_servers='localhost:9092') -> Option D

4. Quick Check:

   Producer uses KafkaProducer with bootstrap_servers [OK]

Hint: Producer uses KafkaProducer with bootstrap_servers [OK]

Common Mistakes:

• Using KafkaConsumer instead of KafkaProducer
• Passing topic during producer creation
• Missing bootstrap_servers parameter

3. Consider this Python code snippet using kafka-python:

from kafka import KafkaProducer, KafkaConsumer

producer = KafkaProducer(bootstrap_servers='localhost:9092')
producer.send('test-topic', b'Hello Kafka')
producer.flush()

consumer = KafkaConsumer('test-topic', bootstrap_servers='localhost:9092', auto_offset_reset='earliest', consumer_timeout_ms=1000)
for msg in consumer:
    print(msg.value.decode())

What will be the output when this code runs?

medium

A. Error: topic not found

B. Hello Kafka

C. No output, consumer times out

D. b'Hello Kafka'

Solution

1. Step 1: Analyze producer sending message

   Producer sends bytes message b'Hello Kafka' to 'test-topic' and flushes to ensure delivery.

2. Step 2: Analyze consumer reading message

   Consumer reads from 'test-topic' from earliest offset and decodes bytes to string before printing.

3. Final Answer:

   Hello Kafka -> Option B

4. Quick Check:

   Consumer prints decoded message string [OK]

Hint: Consumer decodes bytes to string before printing [OK]

Common Mistakes:

• Expecting raw bytes output
• Assuming consumer misses message due to timeout
• Thinking topic does not exist

4. You wrote this code to consume messages but it raises an error:

consumer = KafkaConsumer('my-topic')
for message in consumer:
    print(message.value.decode())

What is the most likely cause of the error?

medium

A. Using decode() on message.value which is already a string

B. Not calling consumer.poll() before iterating

C. Missing bootstrap_servers parameter when creating KafkaConsumer

D. Topic name should be a list, not a string

Solution

1. Step 1: Check KafkaConsumer creation requirements

   KafkaConsumer requires bootstrap_servers parameter to connect to Kafka cluster.

2. Step 2: Validate other options

   decode() is needed because message.value is bytes; consumer.poll() is optional; topic can be string or list.

3. Final Answer:

   Missing bootstrap_servers parameter when creating KafkaConsumer -> Option C

4. Quick Check:

   KafkaConsumer needs bootstrap_servers [OK]

Hint: Always specify bootstrap_servers when creating KafkaConsumer [OK]

Common Mistakes:

• Omitting bootstrap_servers parameter
• Assuming message.value is string without decoding
• Thinking poll() is mandatory before iteration

5. You want to produce and consume the first message in a Kafka topic named 'orders'. Which sequence of steps correctly achieves this in Python using kafka-python?

hard

A. Create KafkaProducer with bootstrap_servers, send message as bytes, flush; create KafkaConsumer with bootstrap_servers and auto_offset_reset='earliest', then read and decode messages

B. Create KafkaConsumer first, then KafkaProducer; send message as string; consumer reads without decoding

C. Create KafkaProducer without bootstrap_servers, send string message; create KafkaConsumer with bootstrap_servers, read messages as bytes

D. Create KafkaProducer with topic parameter, send message; create KafkaConsumer without bootstrap_servers, read and decode messages

Solution

1. Step 1: Properly create KafkaProducer and send message

   KafkaProducer must be created with bootstrap_servers; messages sent as bytes and flushed to ensure delivery.

2. Step 2: Properly create KafkaConsumer and read messages

   KafkaConsumer needs bootstrap_servers and auto_offset_reset='earliest' to read from the first message; decode bytes to string when reading.

3. Final Answer:

   Create KafkaProducer with bootstrap_servers, send message as bytes, flush; create KafkaConsumer with bootstrap_servers and auto_offset_reset='earliest', then read and decode messages -> Option A

4. Quick Check:

   Correct producer and consumer setup with bytes and decoding [OK]

Hint: Producer sends bytes and flushes; consumer reads earliest and decodes [OK]

Common Mistakes:

• Creating producer or consumer without bootstrap_servers
• Sending string instead of bytes
• Not setting auto_offset_reset to 'earliest'
• Not decoding message bytes before printing