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Google Cloud Pub/Sub

Scalable, real-time messaging service for building event-driven systems

What is Cloud Pub/Sub?

Google Cloud Pub/Sub is a fully managed, real-time messaging service that allows you to send and receive messages between independent applications. It implements the publish-subscribe pattern, enabling asynchronous communication between services by decoupling senders (publishers) from receivers (subscribers).

Built on Google's global infrastructure, Cloud Pub/Sub provides reliable, many-to-many, asynchronous messaging that scales automatically to handle millions of messages per second. It serves as the backbone for event-driven architectures, stream analytics, and real-time data integration across distributed systems.

Architecture

Publisher 1 Publisher 2 Publisher 3 Topic Message Queue Ordering & Delivery Subscription A Push/Pull Subscription B Push/Pull Subscription C Push/Pull Subscriber 1 Subscriber 2 Subscriber 3 Publishers Pub/Sub Service Subscriptions Subscribers

Key Components

Topics

Named resources that act as communication channels where publishers send messages. Topics are globally unique within a project.

  • • Message ordering
  • • Schema validation
  • • Message retention

Subscriptions

Named resources representing the stream of messages from a topic to be delivered to subscribing applications.

  • • Push/Pull delivery
  • • Message filtering
  • • Dead letter queues

Messages

Data units that publishers send to topics and subscribers receive from subscriptions, containing payload and attributes.

  • • Up to 10MB payload
  • • Custom attributes
  • • Message ID & timestamp

Key Capabilities

Auto-scaling

Automatically scales to handle millions of messages per second with no manual intervention required.

At-least-once Delivery

Guarantees message delivery with configurable acknowledgment deadlines and retry policies.

Push and Pull Delivery

Supports both push (webhook) and pull (polling) message delivery modes for flexible integration.

Message Filtering

Filter messages at the subscription level based on message attributes to reduce unnecessary processing.

Message Retention

Configurable message retention periods from 10 minutes to 7 days for replay and recovery scenarios.

Common Use Cases

Event-driven Architecture

Decouple microservices with asynchronous messaging

Stream Analytics

Real-time data processing and analytics pipelines

Notifications

Push notifications and alert systems

Data Integration

ETL processes and data synchronization

Task Queues

Background job processing and work distribution

IoT Data Ingestion

Collect and process IoT sensor data at scale

Related Topics

Cloud Functions Cloud Run Dataflow BigQuery Cloud Storage Kubernetes Engine

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