Now that we have covered the Flux API, let's look at Mono. It is capable of generating a maximum of one event. This is a specific use case for Flux, capable of handling one response model, such as data aggregation, HTTP request-response, service invocation response, and so on. It is important to note that a Mono emits the following three events:
- Value refers to the single value generated by the publisher
- Completion refers to a normal termination of the stream
- Error refers to an erroneous termination of the stream
Since Mono is a subset of Flux, it supports a subset of Flux operators. Let's look at how to build a Mono.