Platform Events with Pub/Sub APIs
"Use Pub/Sub API to subscribe to event messages in an external client to integrate your systems. Simplify
your developmentby using one APIto publish, subscribe, and retrieve the event schema. Based on gRPC
and HTTP/2, Pub/Sub API enables efficient delivery of binary event messages in the Apache Avro format."
"Salesforce sends platform events to Pub/Sub API clients sequentially in the order they’re received. The
order of event notifications is based on the replay ID of events. A client can receive a batch of events at
once."
"The event schema is versioned-when the schema changes, the schema ID changes as well."
Source:
https://developer.salesforce.com/docs/atlas.en-us.platform_events.meta/platform_events/platform_events_subscribe_pubsub_api.htm