Hands-On Software Engineering with Golang

The Any type

When building event-driven systems, a common pattern is to define a top-level message that acts as an envelope for different event payloads. Since new event types may be added (or removed) at any point in time, using a union is simply not going to suffice. Furthermore, the following are from the standpoint of event consumers:

• Consumers might ship with older .proto versions than the event producers do. It is quite possible for them to encounter an event payload that they don't really know how to decode.
• Some consumers may only be interested in processing a subset of the events. In such a scenario, consumers should only decode the messages they care about and skip over all other messages.

To cater for such cases, we can use the ...