## Package org.apache.catalina

Interface Summary
Authenticator: An Authenticator is a component (usually a Valve or Container) that provides some sort of authentication service.
Cluster: A Cluster works as a Cluster client/server for the local host Different Cluster implementations can be used to support different ways to communicate within the Cluster.
Connector: A Connector is a component responsible receiving requests from, and returning responses to, a client application.
Contained: Decoupling interface which specifies that an implementing class is associated with at most one Container instance.
Container: A Container is an object that can execute requests received from a client, and return responses based on those requests.
ContainerListener: Interface defining a listener for significant Container generated events.
ContainerServlet: A ContainerServlet is a servlet that has access to Catalina internal functionality, and is loaded from the Catalina class loader instead of the web application class loader.
Context: A Context is a Container that represents a servlet context, and therefore an individual web application, in the Catalina servlet engine.
DefaultContext: Used to store the default configuration a Host will use when creating a Context.
Deployer: A Deployer is a specialized Container into which web applications can be deployed and undeployed.
Engine: An Engine is a Container that represents the entire Catalina servlet engine.
Group: Abstract representation of a group of `User`s in a `UserDatabase`.
Host: A Host is a Container that represents a virtual host in the Catalina servlet engine.
HttpRequest: An HttpRequest is the Catalina internal facade for an `HttpServletRequest` that is to be processed, in order to produce the corresponding `HttpResponse`.
HttpResponse: An HttpResponse is the Catalina-internal facade for an `HttpServletResponse` that is to be produced, based on the processing of a corresponding `HttpRequest`.
InstanceListener: Interface defining a listener for significant events related to a specific servlet instance, rather than to the Wrapper component that is managing that instance.
Lifecycle: Common interface for component life cycle methods.
LifecycleListener: Interface defining a listener for significant events (including "component start" and "component stop" generated by a component that implements the Lifecycle interface.
Loader: A Loader represents a Java ClassLoader implementation that can be used by a Container to load class files (within a repository associated with the Loader) that are designed to be reloaded upon request, as well as a mechanism to detect whether changes have occurred in the underlying repository.
Logger: A Logger is a generic interface for the message and exception logging methods of the ServletContext interface.
Manager: A Manager manages the pool of Sessions that are associated with a particular Container.
Mapper: Interface defining methods that a parent Container may implement to select a subordinate Container to process a particular Request, optionally modifying the properties of the Request to reflect the selections made.
Pipeline: Interface describing a collection of Valves that should be executed in sequence when the `invoke()` method is invoked.
Realm: A Realm is a read-only facade for an underlying security realm used to authenticate individual users, and identify the security roles associated with those users.
Request: A Request is the Catalina-internal facade for a `ServletRequest` that is to be processed, in order to produce the corresponding `Response`.
Response: A Response is the Catalina-internal facade for a `ServletResponse` that is to be produced, based on the processing of a corresponding `Request`.
Role: Abstract representation of a security role, suitable for use in environments like JAAS that want to deal with `Principals`.
Server: A `Server` element represents the entire Catalina servlet container.
Service: A Service is a group of one or more Connectors that share a single Container to process their incoming requests.
Session: A Session is the Catalina-internal facade for an `HttpSession` that is used to maintain state information between requests for a particular user of a web application.
SessionListener: Interface defining a listener for significant Session generated events.
Store: A Store is the abstraction of a Catalina component that provides persistent storage and loading of Sessions and their associated user data.
User: Abstract representation of a user in a `UserDatabase`.
UserDatabase: Abstract representation of a database of `User`s and `Group`s that can be maintained by an application, along with definitions of corresponding `Role`s, and referenced by a `Realm` for authentication and access control.
Valve: A Valve is a request processing component associated with a particular Container.
ValveContext: A ValveContext is the mechanism by which a Valve can trigger the execution of the next Valve in a Pipeline, without having to know anything about the internal implementation mechanisms.
Wrapper: A Wrapper is a Container that represents an individual servlet definition from the deployment descriptor of the web application.

Class Summary
ContainerEvent: General event for notifying listeners of significant changes on a Container.
Globals: Global constants that are applicable to multiple packages within Catalina.
InstanceEvent: General event for notifying listeners of significant events related to a specific instance of a Servlet, or a specific instance of a Filter, as opposed to the Wrapper component that manages it.
LifecycleEvent: General event for notifying listeners of significant changes on a component that implements the Lifecycle interface.
ServerFactory: ServerFactory allows the registration of the (singleton) `Server` instance for this JVM, so that it can be accessed independently of any existing reference to the component hierarchy.
SessionEvent: General event for notifying listeners of significant changes on a Session.

Exception Summary
LifecycleException: General purpose exception that is thrown to indicate a lifecycle related problem.

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