Interface Container

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Apache Tomcat 8.5.54

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org.apache.catalina
Interface Container

All Superinterfaces:
    Lifecycle

All Known Subinterfaces:
    Context, Engine, Host, Wrapper

All Known Implementing Classes:
    ContainerBase, FailedContext, ReplicatedContext, StandardContext, StandardEngine, StandardHost, StandardWrapper, Tomcat.ExistingStandardWrapper


public interface Container
extends Lifecycle

A Container is an object that can execute requests received from a client, and return responses based on those requests. A Container may optionally support a pipeline of Valves that process the request in an order configured at runtime, by implementing the Pipeline interface as well.

Containers will exist at several conceptual levels within Catalina. The following examples represent common cases:
    Engine - Representation of the entire Catalina servlet engine, most likely containing one or more subcontainers that are either Host or Context implementations, or other custom groups.
    Host - Representation of a virtual host containing a number of Contexts.
    Context - Representation of a single ServletContext, which will typically contain one or more Wrappers for the supported servlets.
    Wrapper - Representation of an individual servlet definition (which may support multiple servlet instances if the servlet itself implements SingleThreadModel). 
A given deployment of Catalina need not include Containers at all of the levels described above. For example, an administration application embedded within a network device (such as a router) might only contain a single Context and a few Wrappers, or even a single Wrapper if the application is relatively small. Therefore, Container implementations need to be designed so that they will operate correctly in the absence of parent Containers in a given deployment.

A Container may also be associated with a number of support components that provide functionality which might be shared (by attaching it to a parent Container) or individually customized. The following support components are currently recognized:
    Loader - Class loader to use for integrating new Java classes for this Container into the JVM in which Catalina is running.
    Logger - Implementation of the log() method signatures of the ServletContext interface.
    Manager - Manager for the pool of Sessions associated with this Container.
    Realm - Read-only interface to a security domain, for authenticating user identities and their corresponding roles.
    Resources - JNDI directory context enabling access to static resources, enabling custom linkages to existing server components when Catalina is embedded in a larger server. 

Author:
    Craig R. McClanahan, Remy Maucherat

    Nested Class Summary
        Nested classes/interfaces inherited from interface org.apache.catalina.Lifecycle
        Lifecycle.SingleUse
    Field Summary
    Fields  Modifier and Type 	Field and Description
    static String 	ADD_CHILD_EVENT
    The ContainerEvent event type sent when a child container is added by addChild().
    static String 	ADD_VALVE_EVENT
    The ContainerEvent event type sent when a valve is added by addValve(), if this Container supports pipelines.
    static String 	REMOVE_CHILD_EVENT
    The ContainerEvent event type sent when a child container is removed by removeChild().
    static String 	REMOVE_VALVE_EVENT
    The ContainerEvent event type sent when a valve is removed by removeValve(), if this Container supports pipelines.
        Fields inherited from interface org.apache.catalina.Lifecycle
        AFTER_DESTROY_EVENT, AFTER_INIT_EVENT, AFTER_START_EVENT, AFTER_STOP_EVENT, BEFORE_DESTROY_EVENT, BEFORE_INIT_EVENT, BEFORE_START_EVENT, BEFORE_STOP_EVENT, CONFIGURE_START_EVENT, CONFIGURE_STOP_EVENT, PERIODIC_EVENT, START_EVENT, STOP_EVENT
    Method Summary
    Methods  Modifier and Type 	Method and Description
    void 	addChild(Container child)
    Add a new child Container to those associated with this Container, if supported.
    void 	addContainerListener(ContainerListener listener)
    Add a container event listener to this component.
    void 	addPropertyChangeListener(PropertyChangeListener listener)
    Add a property change listener to this component.
    void 	backgroundProcess()
    Execute a periodic task, such as reloading, etc.
    Container 	findChild(String name)
    Obtain a child Container by name.
    Container[] 	findChildren()
    Obtain the child Containers associated with this Container.
    ContainerListener[] 	findContainerListeners()
    Obtain the container listeners associated with this Container.
    void 	fireContainerEvent(String type, Object data)
    Notify all container event listeners that a particular event has occurred for this Container.
    AccessLog 	getAccessLog()
    Obtain the AccessLog to use to log a request/response that is destined for this container.
    int 	getBackgroundProcessorDelay()
    Get the delay between the invocation of the backgroundProcess method on this container and its children.
    File 	getCatalinaBase()
    Obtain the location of CATALINA_BASE.
    File 	getCatalinaHome()
    Obtain the location of CATALINA_HOME.
    Cluster 	getCluster()
    Get the Cluster for this container.
    String 	getDomain()
    Obtain the JMX domain under which this container will be / has been registered.
    Log 	getLogger()
    Obtain the log to which events for this container should be logged.
    String 	getLogName()
    Return the logger name that the container will use.
    String 	getMBeanKeyProperties()
    Calculate the key properties string to be added to an object's ObjectName to indicate that it is associated with this container.
    String 	getName()
    Return a name string (suitable for use by humans) that describes this Container.
    ObjectName 	getObjectName()
    Obtain the JMX name for this container.
    Container 	getParent()
    Get the parent container.
    ClassLoader 	getParentClassLoader()
    Get the parent class loader.
    Pipeline 	getPipeline()
    Return the Pipeline object that manages the Valves associated with this Container.
    Realm 	getRealm()
    Obtain the Realm with which this Container is associated.
    int 	getStartStopThreads()
    Obtain the number of threads available for starting and stopping any children associated with this container.
    void 	logAccess(Request request, Response response, long time, boolean useDefault)
    Log a request/response that was destined for this container but has been handled earlier in the processing chain so that the request/response still appears in the correct access logs.
    void 	removeChild(Container child)
    Remove an existing child Container from association with this parent Container.
    void 	removeContainerListener(ContainerListener listener)
    Remove a container event listener from this component.
    void 	removePropertyChangeListener(PropertyChangeListener listener)
    Remove a property change listener from this component.
    void 	setBackgroundProcessorDelay(int delay)
    Set the delay between the invocation of the execute method on this container and its children.
    void 	setCluster(Cluster cluster)
    Set the Cluster with which this Container is associated.
    void 	setName(String name)
    Set a name string (suitable for use by humans) that describes this Container.
    void 	setParent(Container container)
    Set the parent Container to which this Container is being added as a child.
    void 	setParentClassLoader(ClassLoader parent)
    Set the parent class loader for this component.
    void 	setRealm(Realm realm)
    Set the Realm with which this Container is associated.
    void 	setStartStopThreads(int startStopThreads)
    Sets the number of threads available for starting and stopping any children associated with this container.
        Methods inherited from interface org.apache.catalina.Lifecycle
        addLifecycleListener, destroy, findLifecycleListeners, getState, getStateName, init, removeLifecycleListener, start, stop

    Field Detail
        ADD_CHILD_EVENT

        static final String ADD_CHILD_EVENT

        The ContainerEvent event type sent when a child container is added by addChild().

        See Also:
            Constant Field Values

        ADD_VALVE_EVENT

        static final String ADD_VALVE_EVENT

        The ContainerEvent event type sent when a valve is added by addValve(), if this Container supports pipelines.

        See Also:
            Constant Field Values

        REMOVE_CHILD_EVENT

        static final String REMOVE_CHILD_EVENT

        The ContainerEvent event type sent when a child container is removed by removeChild().

        See Also:
            Constant Field Values

        REMOVE_VALVE_EVENT

        static final String REMOVE_VALVE_EVENT

        The ContainerEvent event type sent when a valve is removed by removeValve(), if this Container supports pipelines.

        See Also:
            Constant Field Values

    Method Detail
        getLogger

        Log getLogger()

        Obtain the log to which events for this container should be logged.

        Returns:
            The Logger with which this Container is associated. If there is no associated Logger, return the Logger associated with the parent Container (if any); otherwise return null.

        getLogName

        String getLogName()

        Return the logger name that the container will use.

        Returns:
            the abbreviated name of this container for logging messages

        getObjectName

        ObjectName getObjectName()

        Obtain the JMX name for this container.

        Returns:
            the JMX name associated with this container.

        getDomain

        String getDomain()

        Obtain the JMX domain under which this container will be / has been registered.

        Returns:
            The JMX domain name

        getMBeanKeyProperties

        String getMBeanKeyProperties()

        Calculate the key properties string to be added to an object's ObjectName to indicate that it is associated with this container.

        Returns:
            A string suitable for appending to the ObjectName

        getPipeline

        Pipeline getPipeline()

        Return the Pipeline object that manages the Valves associated with this Container.

        Returns:
            The Pipeline

        getCluster

        Cluster getCluster()

        Get the Cluster for this container.

        Returns:
            The Cluster with which this Container is associated. If there is no associated Cluster, return the Cluster associated with our parent Container (if any); otherwise return null.

        setCluster

        void setCluster(Cluster cluster)

        Set the Cluster with which this Container is associated.

        Parameters:
            cluster - the Cluster with which this Container is associated.

        getBackgroundProcessorDelay

        int getBackgroundProcessorDelay()

        Get the delay between the invocation of the backgroundProcess method on this container and its children. Child containers will not be invoked if their delay value is positive (which would mean they are using their own thread). Setting this to a positive value will cause a thread to be spawned. After waiting the specified amount of time, the thread will invoke the backgroundProcess() method on this container and all children with non-positive delay values.

        Returns:
            The delay between the invocation of the backgroundProcess method on this container and its children. A non-positive value indicates that background processing will be managed by the parent.

        setBackgroundProcessorDelay

        void setBackgroundProcessorDelay(int delay)

        Set the delay between the invocation of the execute method on this container and its children.

        Parameters:
            delay - The delay in seconds between the invocation of backgroundProcess methods

        getName

        String getName()

        Return a name string (suitable for use by humans) that describes this Container. Within the set of child containers belonging to a particular parent, Container names must be unique.

        Returns:
            The human readable name of this container.

        setName

        void setName(String name)

        Set a name string (suitable for use by humans) that describes this Container. Within the set of child containers belonging to a particular parent, Container names must be unique.

        Parameters:
            name - New name of this container
        Throws:
            IllegalStateException - if this Container has already been added to the children of a parent Container (after which the name may not be changed)

        getParent

        Container getParent()

        Get the parent container.

        Returns:
            Return the Container for which this Container is a child, if there is one. If there is no defined parent, return null.

        setParent

        void setParent(Container container)

        Set the parent Container to which this Container is being added as a child. This Container may refuse to become attached to the specified Container by throwing an exception.

        Parameters:
            container - Container to which this Container is being added as a child
        Throws:
            IllegalArgumentException - if this Container refuses to become attached to the specified Container

        getParentClassLoader

        ClassLoader getParentClassLoader()

        Get the parent class loader.

        Returns:
            the parent class loader for this component. If not set, return getParent().getParentClassLoader(). If no parent has been set, return the system class loader.

        setParentClassLoader

        void setParentClassLoader(ClassLoader parent)

        Set the parent class loader for this component. For Contexts this call is meaningful only before a Loader has been configured, and the specified value (if non-null) should be passed as an argument to the class loader constructor.

        Parameters:
            parent - The new parent class loader

        getRealm

        Realm getRealm()

        Obtain the Realm with which this Container is associated.

        Returns:
            The associated Realm; if there is no associated Realm, the Realm associated with the parent Container (if any); otherwise return null.

        setRealm

        void setRealm(Realm realm)

        Set the Realm with which this Container is associated.

        Parameters:
            realm - The newly associated Realm

        backgroundProcess

        void backgroundProcess()

        Execute a periodic task, such as reloading, etc. This method will be invoked inside the classloading context of this container. Unexpected throwables will be caught and logged.
        addChild

        void addChild(Container child)

        Add a new child Container to those associated with this Container, if supported. Prior to adding this Container to the set of children, the child's setParent() method must be called, with this Container as an argument. This method may thrown an IllegalArgumentException if this Container chooses not to be attached to the specified Container, in which case it is not added

        Parameters:
            child - New child Container to be added
        Throws:
            IllegalArgumentException - if this exception is thrown by the setParent() method of the child Container
            IllegalArgumentException - if the new child does not have a name unique from that of existing children of this Container
            IllegalStateException - if this Container does not support child Containers

        addContainerListener

        void addContainerListener(ContainerListener listener)

        Add a container event listener to this component.

        Parameters:
            listener - The listener to add

        addPropertyChangeListener

        void addPropertyChangeListener(PropertyChangeListener listener)

        Add a property change listener to this component.

        Parameters:
            listener - The listener to add

        findChild

        Container findChild(String name)

        Obtain a child Container by name.

        Parameters:
            name - Name of the child Container to be retrieved
        Returns:
            The child Container with the given name or null if no such child exists.

        findChildren

        Container[] findChildren()

        Obtain the child Containers associated with this Container.

        Returns:
            An array containing all children of this container. If this Container has no children, a zero-length array is returned.

        findContainerListeners

        ContainerListener[] findContainerListeners()

        Obtain the container listeners associated with this Container.

        Returns:
            An array containing the container listeners associated with this Container. If this Container has no registered container listeners, a zero-length array is returned.

        removeChild

        void removeChild(Container child)

        Remove an existing child Container from association with this parent Container.

        Parameters:
            child - Existing child Container to be removed

        removeContainerListener

        void removeContainerListener(ContainerListener listener)

        Remove a container event listener from this component.

        Parameters:
            listener - The listener to remove

        removePropertyChangeListener

        void removePropertyChangeListener(PropertyChangeListener listener)

        Remove a property change listener from this component.

        Parameters:
            listener - The listener to remove

        fireContainerEvent

        void fireContainerEvent(String type,
                              Object data)

        Notify all container event listeners that a particular event has occurred for this Container. The default implementation performs this notification synchronously using the calling thread.

        Parameters:
            type - Event type
            data - Event data

        logAccess

        void logAccess(Request request,
                     Response response,
                     long time,
                     boolean useDefault)

        Log a request/response that was destined for this container but has been handled earlier in the processing chain so that the request/response still appears in the correct access logs.

        Parameters:
            request - Request (associated with the response) to log
            response - Response (associated with the request) to log
            time - Time taken to process the request/response in milliseconds (use 0 if not known)
            useDefault - Flag that indicates that the request/response should be logged in the engine's default access log

        getAccessLog

        AccessLog getAccessLog()

        Obtain the AccessLog to use to log a request/response that is destined for this container. This is typically used when the request/response was handled (and rejected) earlier in the processing chain so that the request/response still appears in the correct access logs.

        Returns:
            The AccessLog to use for a request/response destined for this container

        getStartStopThreads

        int getStartStopThreads()

        Obtain the number of threads available for starting and stopping any children associated with this container. This allows start/stop calls to children to be processed in parallel.

        Returns:
            The currently configured number of threads used to start/stop children associated with this container

        setStartStopThreads

        void setStartStopThreads(int startStopThreads)

        Sets the number of threads available for starting and stopping any children associated with this container. This allows start/stop calls to children to be processed in parallel.

        Parameters:
            startStopThreads - The new number of threads to be used

        getCatalinaBase

        File getCatalinaBase()

        Obtain the location of CATALINA_BASE.

        Returns:
            The location of CATALINA_BASE.

        getCatalinaHome

        File getCatalinaHome()

        Obtain the location of CATALINA_HOME.

        Returns:
            The location of CATALINA_HOME.

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Apache Tomcat 8.5.54

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