GCP - Cloud PubSub

Topics are subscriptions are within a project. Resource names:

• //pubsub.googleapis.com/projects/PROJECT_ID/topics/TOPIC
• //pubsub.googleapis.com/projects/PROJECT_ID/subscriptions/SUBSCRIPTION

Subscription types:

• Pull: the subscriber requests messages from the Pub/Sub server.
• Push: the subscriber creates a endpoint; Pub/Sub server calls the endpoint to "push" a message.
• Export: export messages to a GCP service, e.g. BigQuery, GCS.

Eventarc

Eventarc is built on top of Pub/Sub. While Eventarc provides a higher-level abstraction for event-driven architectures and simplifies the process of reacting to events, it uses Pub/Sub internally for the reliable and scalable delivery of those events.