API specification: An OpenAPI document (in YAML or JSON format) that describes a REST API. It specifies the metadata (verbs, paths, headers, and so on) a client needs to make a valid request to the API.
Application: A container of components.
Connector: An interface that abstracts underlying backend systems (for example, database, web service, and so on).
Context: An encapsulation of request and response objects provides useful values for writing web applications and APIs. For more information, see Context.
Controller: The implementation of API endpoints.
DataSource: A named configuration for a Connector instance that represents data in an external system.
Element: The building blocks of a Sequence, such as route, params, and result. For more information, see Sequence.
Mixin: An interface for models.
Model: Defines application data and how it is connected to other data.
Sequence: A stateless grouping of actions that control how an Application responds to requests.
Service: Operations implemented in an external system.
Repository: A type of Service that represents a collection of data within a DataSource. For more information, see Repositories.