Topics & Subscriptions

Topics and subscriptions are the two fundamental resources in Google Cloud Pub/Sub. Topics are where publishers send messages, and subscriptions are how subscribers receive them. Understanding how to create, configure, and manage these resources is essential for building reliable messaging systems.

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Topics in Depth

A topic is a named resource that acts as a message channel. Publishers send messages to a topic, and Pub/Sub distributes copies of each message to all subscriptions attached to that topic.

Creating and Managing Topics

# Create a topic
gcloud pubsub topics create orders-topic

# Create a topic with a schema for message validation
gcloud pubsub topics create orders-topic \
  --schema=orders-schema \
  --message-encoding=json

# Add labels for organisation and billing
gcloud pubsub topics update orders-topic \
  --update-labels=team=payments,env=production

# Delete a topic (does not delete subscriptions)
gcloud pubsub topics delete orders-topic

Topic Configuration