org.apache.catalina
Interface Container

All Known Subinterfaces:

Context, Engine, Host, Wrapper

All Known Implementing Classes:

ContainerBase, StandardContext, StandardEngine, StandardHost, StandardWrapper

public interface Container

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.

Version:

$Revision: 1.6 $ $Date: 2003/07/18 18:48:58 $

Author:

Craig R. McClanahan, Remy Maucherat

Field Summary

static java.lang.String	ADD_CHILD_EVENT The ContainerEvent event type sent when a child container is added by addChild().
static java.lang.String	ADD_MAPPER_EVENT The ContainerEvent event type sent when a Mapper is added by addMapper().
static java.lang.String	ADD_VALVE_EVENT The ContainerEvent event type sent when a valve is added by addValve(), if this Container supports pipelines.
static java.lang.String	REMOVE_CHILD_EVENT The ContainerEvent event type sent when a child container is removed by removeChild().
static java.lang.String	REMOVE_MAPPER_EVENT The ContainerEvent event type sent when a Mapper is removed by removeMapper().
static java.lang.String	REMOVE_VALVE_EVENT The ContainerEvent event type sent when a valve is removed by removeValve(), if this Container supports pipelines.

Method Summary

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(java.beans.PropertyChangeListener listener) Add a property change listener to this component.
void	backgroundProcess() Execute a periodic task, such as reloading, etc.
Container	findChild(java.lang.String name) Return the child Container, associated with this Container, with the specified name (if any); otherwise, return null
Container[]	findChildren() Return the set of children Containers associated with this Container.
ContainerListener[]	findContainerListeners() Return the set of container listeners associated with this Container.
int	getBackgroundProcessorDelay() Get the delay between the invocation of the backgroundProcess method on this container and its children.
Cluster	getCluster() Return the Cluster with which this Container is associated.
java.lang.String	getInfo() Return descriptive information about this Container implementation and the corresponding version number, in the format <description>/<version>.
Loader	getLoader() Return the Loader with which this Container is associated.
Logger	getLogger() Return the Logger with which this Container is associated.
Manager	getManager() Return the Manager with which this Container is associated.
java.lang.Object	getMappingObject() Return an object which may be utilized for mapping to this component.
java.lang.String	getName() Return a name string (suitable for use by humans) that describes this Container.
Container	getParent() Return the Container for which this Container is a child, if there is one.
java.lang.ClassLoader	getParentClassLoader() Return the parent class loader (if any) for web applications.
Pipeline	getPipeline() Return the Pipeline object that manages the Valves associated with this Container.
Realm	getRealm() Return the Realm with which this Container is associated.
javax.naming.directory.DirContext	getResources() Return the Resources with which this Container is associated.
void	invoke(Request request, Response response) Process the specified Request, and generate the corresponding Response, according to the design of this particular Container.
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(java.beans.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	setLoader(Loader loader) Set the Loader with which this Container is associated.
void	setLogger(Logger logger) Set the Logger with which this Container is associated.
void	setManager(Manager manager) Set the Manager with which this Container is associated.
void	setName(java.lang.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(java.lang.ClassLoader parent) Set the parent class loader (if any) for web applications.
void	setRealm(Realm realm) Set the Realm with which this Container is associated.
void	setResources(javax.naming.directory.DirContext resources) Set the Resources object with which this Container is associated.

Field Detail

ADD_CHILD_EVENT

public static final java.lang.String ADD_CHILD_EVENT

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

See Also:

Constant Field Values

ADD_MAPPER_EVENT

public static final java.lang.String ADD_MAPPER_EVENT

The ContainerEvent event type sent when a Mapper is added by addMapper().

See Also:

Constant Field Values

ADD_VALVE_EVENT

public static final java.lang.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

public static final java.lang.String REMOVE_CHILD_EVENT

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

See Also:

Constant Field Values

REMOVE_MAPPER_EVENT

public static final java.lang.String REMOVE_MAPPER_EVENT

The ContainerEvent event type sent when a Mapper is removed by removeMapper().

See Also:

Constant Field Values

REMOVE_VALVE_EVENT

public static final java.lang.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

getInfo

public java.lang.String getInfo()

Return descriptive information about this Container implementation and the corresponding version number, in the format <description>/<version>.

getLoader

public Loader getLoader()

Return the Loader with which this Container is associated. If there is no associated Loader, return the Loader associated with our parent Container (if any); otherwise, return null.

setLoader

public void setLoader(Loader loader)

Set the Loader with which this Container is associated.

Parameters:

loader - The newly associated loader

getLogger

public Logger getLogger()

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

setLogger

public void setLogger(Logger logger)

Set the Logger with which this Container is associated.

Parameters:

logger - The newly associated Logger

getManager

public Manager getManager()

Return the Manager with which this Container is associated. If there is no associated Manager, return the Manager associated with our parent Container (if any); otherwise return null.

setManager

public void setManager(Manager manager)

Set the Manager with which this Container is associated.

Parameters:

manager - The newly associated Manager

getMappingObject

public java.lang.Object getMappingObject()

Return an object which may be utilized for mapping to this component.

getPipeline

public Pipeline getPipeline()

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

getCluster

public Cluster getCluster()

Return 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

public void setCluster(Cluster cluster)

Set the Cluster with which this Container is associated.

getBackgroundProcessorDelay

public 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 not negative (which would mean they are using their own thread). Setting this to a positive value will cause a thread to be spawn. After waiting the specified amount of time, the thread will invoke the executePeriodic method on this container and all its children.

setBackgroundProcessorDelay

public 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

public java.lang.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.

setName

public void setName(java.lang.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:

java.lang.IllegalStateException - if this Container has already been added to the children of a parent Container (after which the name may not be changed)

getParent

public Container getParent()

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

setParent

public 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:

java.lang.IllegalArgumentException - if this Container refuses to become attached to the specified Container

getParentClassLoader

public java.lang.ClassLoader getParentClassLoader()

Return the parent class loader (if any) for web applications.

setParentClassLoader

public void setParentClassLoader(java.lang.ClassLoader parent)

Set the parent class loader (if any) for web applications. 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

public Realm getRealm()

Return the Realm with which this Container is associated. If there is no associated Realm, return the Realm associated with our parent Container (if any); otherwise return null.

setRealm

public void setRealm(Realm realm)

Set the Realm with which this Container is associated.

Parameters:

realm - The newly associated Realm

getResources

public javax.naming.directory.DirContext getResources()

Return the Resources with which this Container is associated. If there is no associated Resources object, return the Resources associated with our parent Container (if any); otherwise return null.

setResources

public void setResources(javax.naming.directory.DirContext resources)

Set the Resources object with which this Container is associated.

Parameters:

resources - The newly associated Resources

backgroundProcess

public 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

public 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:

java.lang.IllegalArgumentException - if this exception is thrown by the setParent() method of the child Container

java.lang.IllegalArgumentException - if the new child does not have a name unique from that of existing children of this Container

java.lang.IllegalStateException - if this Container does not support child Containers

addContainerListener

public void addContainerListener(ContainerListener listener)

Add a container event listener to this component.

Parameters:

listener - The listener to add

addPropertyChangeListener

public void addPropertyChangeListener(java.beans.PropertyChangeListener listener)

Add a property change listener to this component.

Parameters:

listener - The listener to add

findChild

public Container findChild(java.lang.String name)

Return the child Container, associated with this Container, with the specified name (if any); otherwise, return null

Parameters:

name - Name of the child Container to be retrieved

findChildren

public Container[] findChildren()

Return the set of children Containers associated with this Container. If this Container has no children, a zero-length array is returned.

findContainerListeners

public ContainerListener[] findContainerListeners()

Return the set of container listeners associated with this Container. If this Container has no registered container listeners, a zero-length array is returned.

invoke

public void invoke(Request request,
                   Response response)
            throws java.io.IOException,
                   javax.servlet.ServletException

Process the specified Request, and generate the corresponding Response, according to the design of this particular Container.

Parameters:

request - Request to be processed

response - Response to be produced

Throws:

java.io.IOException - if an input/output error occurred while processing

javax.servlet.ServletException - if a ServletException was thrown while processing this request

removeChild

public void removeChild(Container child)

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

Parameters:

child - Existing child Container to be removed

removeContainerListener

public void removeContainerListener(ContainerListener listener)

Remove a container event listener from this component.

Parameters:

listener - The listener to remove

removePropertyChangeListener

public void removePropertyChangeListener(java.beans.PropertyChangeListener listener)

Remove a property change listener from this component.

Parameters:

listener - The listener to remove