Pub/sub limitations (no persistence) in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to subscribe to a Redis channel named 'news'.

Redis

SUBSCRIBE [1]

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

Amessages

Bupdates

Cchannel1

Dnews

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different channel name than 'news'.

Forgetting to specify the channel name.

The SUBSCRIBE command listens to the specified channel. Here, 'news' is the correct channel name.

2fill in blank

medium

Complete the code to publish the message 'Hello' to the 'news' channel.

Redis

PUBLISH [1] 'Hello'

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

Aupdates

Bchannel1

Cnews

Dmessages

Attempts:

3 left

💡 Hint

Common Mistakes

Publishing to the wrong channel.

Omitting the channel name.

The PUBLISH command sends a message to the specified channel. Here, 'news' is the correct channel.

3fill in blank

hard

Fix the error in the code to subscribe to multiple channels: 'news' and 'updates'.

Redis

SUBSCRIBE [1] [2]

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

Anews

Bupdates

Cnews,updates

D'news' 'updates'

Attempts:

3 left

💡 Hint

Common Mistakes

Using commas to separate channel names.

Adding quotes around channel names.

The SUBSCRIBE command accepts multiple channel names separated by spaces, not commas or quotes.

4fill in blank

hard

Fill both blanks to explain why messages sent before subscription are missed.

Redis

Redis Pub/Sub [1] messages and [2] them for later delivery.

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

Adoes not store

Bstores

Cdoes not queue

Dqueues

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking Redis queues messages for later.

Assuming messages are stored for offline clients.

Redis Pub/Sub does not store or queue messages. If a client is not subscribed when a message is sent, it misses that message.

5fill in blank

hard

Fill all three blanks to describe a limitation of Redis Pub/Sub.

Redis

If a subscriber [1] before a message is published, it [2] the message because Redis Pub/Sub [3] persistence.

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

Aconnects

Bmisses

Clacks

Ddisconnects

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'connects' instead of 'disconnects'.

Assuming Redis Pub/Sub has message persistence.

If a subscriber disconnects before a message is published, it misses the message because Redis Pub/Sub lacks persistence.