Enterprise service bus in a nutshell

Event processing consists of taking one or more events from an event stream and applying actions over those events. In general, in an enterprise service bus, there are commodity services; the most common are the following:

Data transformation

Event handling

Protocol conversion

Data mapping

Message processing in the majority of cases involves the following:

Message structure validation against a message schema

Given an event stream, filtering the messages from the stream

Message enrichment with additional data

Message aggregation (composition) from two or more message to produce a new message

https://www.ibm.com/docs/en/ftmswsfz324?topic=components-message-validation