Cloud Pub/Sub

It is a message-oriented middleware to the cloud that is simple and provides scalability, flexibility, and reliability for streaming analytics and event-driven computing systems.

It provides many-to-many asynchronous messaging, decoupling senders and receivers. It allows secure and highly available communication between independently written applications. The following image shows the architecture of Cloud Pub/Sub:

When to use

The following table illustrates some of the use cases for Google Pub/Sub:

Balancing workloads in a network cluster	Efficiently distributing a large queue of tasks among multiple workers, like GCE
Implementing asynchronous workflows	An order processing application can place...