As usual, we'll take the plunge into our refactor with the inventory management module and the Book entity. We want to build out both ViewBuilder and View for Book so that we can build its read projection and be able to query against it again. We'll have to make some changes to our common code first so that we have a good framework to build our CQRS implementation on top of it. I'll start with describing those changes and then we can jump into the Book read-model implementation.
When discussing the high-level approach we can use to build our read models, we decided that eventsByTag was the Persistence Query feature to leverage. We wanted to tag our events with two String tags—the entity type and the event type. We'll implement this tagging process in the ProtobufDatamodelAdapter class that we created in Detaching the domain model from the data model section in Chapter 4, Making History with Event Sourcing. Before...