Eventual consistency in Microservices - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to represent the basic idea of eventual consistency in microservices.

Microservices

service_state = 'stale'
# After some time, the state becomes [1]

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

Ainconsistent

Bimmediate

Cconsistent

Dpermanent

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'immediate' because it sounds fast

Confusing 'inconsistent' as the final state

Eventual consistency means the system will become consistent after some time, not immediately.

2fill in blank

medium

Complete the code to show how a microservice might handle updates asynchronously for eventual consistency.

Microservices

def update_data(data):
    # Send update to message queue
    message_queue.[1](data)

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

Apublish

Breceive

Cdelete

Dprocess

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'receive' which is for consuming messages

Using 'delete' which removes data

To achieve eventual consistency, updates are published to a message queue for asynchronous processing.

3fill in blank

hard

Fix the error in the code that processes messages to update the local state eventually.

Microservices

def process_message(msg):
    # Update local state
    local_state = [1]

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Amsg

Bmsg.data

Cmsg.process()

Dmsg.update()

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning the whole message object instead of its data

Calling non-existent methods on the message

The local state should be updated with the actual data from the message, which is msg.data.

4fill in blank

hard

Fill both blanks to complete the code that checks if the local state is eventually consistent with the source.

Microservices

if local_state [1] source_state:
    print('States are consistent')
else:
    print('States are [2]')

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A==

B!=

Cconsistent

Dinconsistent

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' in the if condition

Confusing 'consistent' and 'inconsistent' in the print statements

We check if the local state is equal (==) to the source state. If not, states are inconsistent.

5fill in blank

hard

Fill all three blanks to complete the code that implements a retry mechanism for eventual consistency.

Microservices

def retry_update(data, attempts=3):
    for i in range(attempts):
        success = send_update(data)
        if success:
            return [1]
    return [2]

result = retry_update(new_data)
print('Update [3]' if result else 'Update failed')

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

ATrue

BFalse

Csucceeded

Dfailed

Attempts:

3 left

💡 Hint

Common Mistakes

Returning False on success

Printing 'failed' when update succeeded

The function returns True on success and False if all retries fail. The print statement shows 'Update succeeded' if result is True.