This view describes the hexagonal reference architecture for a typical bounded context (BC) in the Farmacy Food system. The diagram shows the interaction between external components and the Farmacy Food BC via adapters. This hexagonal architecture prescribes that technology-specific logic be placed in adapters, which isolate the application and domain layers.
The execution of an inbound adapter is activated by an external element. These adapters typically call logic that is not technology specific and resides in the Application and Domain layers in the center.
Outbound adapters are used by the application to interact with other external elements: reading or writing to/from databases, calling http services, publishing events to a message broker topic.
The hexagons are layers and hence the hexagonal architecture is a layered architecture. In our hexagonal architecture, the constraint is that modules in an outer layer can use modules in any inner layer. There's one exception: modules in the application layer can use outbound adapter modules (via interfaces and dependency inversion to avoid platform-specific dependencies in the application layer).
- An inbound REST adapter exposes http endpoints and handles the requests from outside components.
- If you create an inbound REST adapter using for example the Spring MVC framework, the REST adapter would typically
consist of one or more
@RestControllerclasses. - An outbound REST adapter makes calls to http services. It typically offers a function interface that is called by the application and then translates that function call into a http request.
- You can use for example the Open Feign framework to implement an outbound REST adapter.
- Application elements are called from adapters and provide communication with the domain.
- In general, domain objects cannot leak outside of the domain area. Ordinarily, domain objects are wrapped in DTOs (Data Transfer Objects) and returned to outside elements.
- Executes scheduled tasks typically following a cron table.
- Typically, these are tasks pool components like REST services or datasources. Their purpose can be, for example, to synchronize data between a primary data store and its replicas, or to call third-party systems to get updates or activate processes.
- N/A.