NOTE: links in docs and changes in docs will become available only after release!
Improvements
Delta Compression in channels. Utilizing the Fossil delta algorithm, this feature reduces bandwidth costs by sending only the differences from the previous publication. The effectiveness of delta compression varies depending on the data within the channels. It requires support from the Centrifugo SDK and is only available in the Centrifugo JavaScript SDK at this point (starting from centrifuge-js v5.2.0), and only for client-side subscriptions. For more insights about delta compression, and also other compression configurations within different Centrifugo protocol formats, read our new blog post Experimenting with Real-Time Data Compression by Simulating Football Match Events.
Cache Recovery Mode in channels. This allows Centrifugo to function as a real-time key-value store. When a client first subscribes to a channel with recovery enabled and recover flag on, the latest publication from the history stream is immediately sent to the subscriber. On resubscription, the latest publication is also delivered (only if needed, based on the provided offset). This improvement addresses #745.
Add new option: client_connect_include_server_time. When enabled – Centrifugo includes server time in the connection reply/push [#817], resolves #787. The time is sent as a Unix timestamp in milliseconds. Currently, SDK support is not available since the use case in the issue involves unidirectional transport, we can add time to the connected event context in future SDK releases, let us know if you need it.
Add new metric: centrifugo_node_pub_sub_lag_seconds (histogram) to monitor PUB/SUB timings: from time since publication was published till time it reached broadcast (does not include broadcast itself, see another metric below).
Performance optimizations for WebSocket Upgrade. The number of allocations per Upgrade operation has been reduced, making connection establishment stage slightly more efficient.
Many improvements in documentation - more clear description of features, new diagrams, several typos fixed. Also, one Easter Egg (tip: set lights to up in localStorage, use dark theme).
Fixes
Kafka Consumer: Proper parallelism for partition processing #814 – ensures that the processing of all partitions is not blocked when a single partition is blocked for some reason.
More careful positioning: avoid subscriber insufficient state due to PUB/SUB lag. Centrifugo now skips publications coming from PUB/SUB layer to positioned connection with the correct epoch but with offset smaller than position offset. This should prevent occasional insufficient states upon subscribing.
NOTE: links in docs and changes in docs will become available only after release!
Improvements
timein the connection reply/push [#817], resolves #787. The time is sent as a Unix timestamp in milliseconds. Currently, SDK support is not available since the use case in the issue involves unidirectional transport, we can add time to theconnectedevent context in future SDK releases, let us know if you need it.codelabel.lightstoupin localStorage, use dark theme).Fixes
Miscellaneous