Guide to Pub/Sub in Golang

The Publish/Subscribe (Pub/Sub) pattern is a communication method that allows for real-time messages to be sent from one device, known as the Publisher, to other devices called Subscribers. This is done through a message broker which receives messages from Publishers and then sends them to relevant Subscribers. Topics or channels are used to identify who each message should be sent to. The key advantage of using this pattern is that it allows for dynamic message distribution without any actions on the Publisher's end, and subscribers don't need to repeatedly poll a publisher for updates nor communicate directly with them. This makes it ideal for applications like chat apps where clients can both publish messages and subscribe to them. In Go, this pattern is particularly well-fitted due to its inherent design principles of scalability and concurrency. It uses channels to communicate between goroutines, allowing multiple goroutines to both publish and subscribe to these channels. This makes it one of the most well-suited languages for extending this Pub/Sub functionality to networked communication. Ably is a protocol that can be used on top of WebSockets for pub/sub in Golang, allowing you to communicate over WebSockets by using a higher-level set of capabilities. It supports features like ensuring the ordering of messages and providing compression methods for communication. A simple chat application can be created using Ably's Go library, which allows users to connect with a unique identifier, retrieve the history of chat on the channel, and publish and subscribe to messages. This application can also use Presence to identify a user and listen for when people enter or leave the chat. Overall, Pub/Sub is an extremely powerful pattern that complements Go's inherent distributed bias. It can turn complex communications problems into more manageable chunks by separating publishers from subscribers, making it particularly versatile in its use.