Hexagonal Architecture (http://alistair.cockburn.us/Hexagonal+architecture), as shown in the following diagram, aims to decouple the business logic from the persistence and the service layer. Clojure provides the concept of a protocol (https://clojure.org/reference/protocols) that can be used to define the interfaces, that act as ports of Hexagonal Architecture. These ports can then be implemented by the adapters, resulting in a decoupled implementation that can be swapped based on the requirement. Execution of these adapters can then be triggered via Pedestal interceptors based on the business logic.
The interceptor chain must be defined for each microservice of the Helping Hands application separately. Each interceptor chain may consist of interceptors that authenticate the request, validate the data models, and apply the business logic. Interceptors can also be added to interact with the Persistence layer and...