v5.2.0

Centrifugo is an open-source scalable real-time messaging server. Centrifugo can instantly deliver messages to application online users connected over supported transports (WebSocket, HTTP-streaming, SSE/EventSource, GRPC, SockJS, WebTransport). Centrifugo has the concept of a channel – so it's a user-facing PUB/SUB server.

Centrifugo is language-agnostic and can be used to build chat apps, live comments, multiplayer games, real-time data visualizations, collaborative tools, etc. in combination with any backend. It is well suited for modern architectures and allows decoupling the business logic from the real-time transport layer.

Several official client SDKs for browser and mobile development wrap the bidirectional protocol. In addition, Centrifugo supports a unidirectional approach for simple use cases with no SDK dependency.

For details, go to the Centrifugo documentation site.

What's changed

Improvements

• Launching the official tutorial showing the process of building complex real-time application with Centrifugo in detail. It's called Grand Tutorial, and we have a special section on the site for it. In the tutorial we build a WebSocket chat (messenger) app with Django, React and Centrifugo. We cover various aspects of building a production-grade app with Centrifugo and going beyond basics usually shown in instant messaging app tutorials. The idea to keep it in a separate section on the site instead of a blog is to maintain the tutorial actual and extend as time goes.
• Introducing built-in asynchronous consumers. From PostgreSQL outbox table (to natively support transactional outbox) and from Kafka topics. Notably, the "Grand Tutorial" mentioned earlier demonstrates the practical use of both built-in consumers, including the Change Data Capture (CDC) approach for streaming data to Centrifugo using the Debezium connector for PostgreSQL with Kafka Connect.
• Centrifugo now offers the capability to specify an idempotency_key when invoking publish or broadcast server API methods. This is a key Centrifugo will use to prevent duplicate sending of the same publication to a channel. This allows making effective retries when publishing to Centrifugo. Centrifugo maintains a cache of results associated with the used idempotency keys during publishing for a duration of 5 minutes. This cache is utilized to prevent the redundant publication of a message and its addition to the message history if it already exists in the cache. See updated docs for publish and broadcast server APIs.
• Refactor MakeTLSConfig and support mTLS on server by @tie, see #739. This means mTLS is supported for all TLS configurations in Centrifugo – by using TLS options tls_client_ca or tls_client_ca_pem.
• Added possibility to set parallel boolean flag in batch API – to make batch commands processing parallel on Centrifugo side, potentially reducing latency, especially when using the Redis engine, as there is no need to wait for N * RTT (Round Trip Time) for sequential command processing.

Misc

• Release is built using Go v1.21.5
• Improvements to the code base by introducing the use of the Service interface with a Run(ctx context.Context) error method. This approach is now recommended for the proper initiation and termination of various extension services within Centrifugo.