Topics and subscriptions in GCP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a topic in Google Cloud Pub/Sub?

A topic is a named resource to which messages are sent by publishers. It acts like a mailbox where messages are stored until subscribers receive them.

beginner

What is a subscription in Google Cloud Pub/Sub?

A subscription is a named resource representing the stream of messages from a single, specific topic, to be delivered to the subscriber.

intermediate

How do topics and subscriptions work together?

Publishers send messages to topics. Subscribers create subscriptions to those topics to receive messages. Each subscription gets its own copy of every message sent to the topic.

intermediate

What happens if a subscriber does not acknowledge a message in Pub/Sub?

The message remains unacknowledged and will be redelivered after a deadline, ensuring reliable delivery until acknowledged.

beginner

Can a topic have multiple subscriptions in Google Cloud Pub/Sub?

Yes, a topic can have multiple subscriptions. Each subscription independently receives all messages published to the topic.

What is the role of a topic in Google Cloud Pub/Sub?

A It deletes messages after delivery

B It delivers messages to subscribers

C It processes messages before delivery

D It stores messages sent by publishers

A topic stores messages sent by publishers until subscribers receive them.

What does a subscription represent in Pub/Sub?

A A stream of messages from a topic to a subscriber

B A message queue for a topic

C A publisher sending messages

D A storage bucket for messages

A subscription represents the stream of messages from a topic to a subscriber.

If a subscriber does not acknowledge a message, what happens?

A The message is redelivered after a deadline

B The message is lost

C The message is deleted immediately

D The subscription is deleted

Unacknowledged messages are redelivered after a deadline to ensure reliable delivery.

Can one topic have multiple subscriptions?

A No, only one subscription per topic

B No, subscriptions belong to different topics

C Yes, each subscription receives all messages

D Yes, but subscriptions share messages

A topic can have multiple subscriptions, each receiving all messages independently.

Who sends messages to a topic in Pub/Sub?

A Subscribers

B Publishers

C Subscriptions

D Cloud Storage

Publishers send messages to topics.

Explain how topics and subscriptions work together in Google Cloud Pub/Sub.

Think of topics as mailboxes and subscriptions as mailboxes' readers.

Describe what happens when a message is not acknowledged by a subscriber.

Consider how Pub/Sub guarantees message delivery.