4.6. Containers

The Engine represents the entity that processes the requests received by the parent Service; that is, the engine accepts requests from all Connectors defined for the Service, processes them, and returns them to the appropriate Connector.

To define the virtual host of the server that the engine can use, nest multiple Host elements inside the Engine element; each Host element represents one virtual host. You need to define at least one Host element and one of the Hosts must have a name that matches the defaultHost value defined in the parent Engine element.

The Engine element can contain at most one Realm element. The Realm element represents a database of users and their roles: the user information defined in the respective resource is shared across all Hosts and Contexts nested inside the Engine. Realm setting in the Engine element can be overridden by another Realm element defined in a lower-level element; that is, a Host or Context element.