Enterprises need a reliable messaging system for communication between different applications. Not all applications run at the same time to send and receive messages. Sometimes the sending and receiving applications need to be scaled to the same level to run concurrently to send and receive messages. Sometimes not all messages need to be processed by the receiving application. To solve such problems, Google Cloud offers the Google Cloud Pub/Sub service. If your vision is to create a real-time reporting and analytics tool for your company, then Google Cloud Pub/Sub will be the backbone for that vision.

Google Cloud Pub/Sub is a reliable and durable messaging system that decouples senders and receivers and allows applications to asynchronously send and receive messages. Most of the services on Google Cloud, such as Compute Engine, Cloud Storage, App Engine, and Cloud Dataflow, can write messages to Pub/Sub and also receive messages from Pub/Sub. The following are the terms used in Pub/Sub to denote various entities and operations:

• Topic: A topic is like a label for the email. It is used to categorize messages sent in Cloud Pub/Sub.
• Subscription: The subscription is the process that takes place to receive messages belonging to specific topics.
• Message: This is the actual message to be sent to the subscriber.
• Message attributes: The data to be sent along with the message, and this is optional.