Container (Apache Tomcat 8.0.15 API Documentation)

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

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)` 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.
`void`	`fireContainerEvent(String type, Object data)` Notify all container event listeners that a particular event has occurred for this Container.
`AccessLog`	`getAccessLog()` Identify the AccessLog to use to log a request/response that was destined for this container but was handled earlier in the processing chain so that the request/response still appears in the correct access logs.
`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`	`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()` Return the Realm with which this Container is associated.
`int`	`getStartStopThreads()` Returns 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.
  - 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()
```
    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
```
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)
```
    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
```
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
```
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.
  - 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()
```
    Identify the AccessLog to use to log a request/response that was destined for this container but was handled earlier in the processing chain so that the request/response still appears in the correct access logs.
  - getStartStopThreads
```
int getStartStopThreads()
```
    Returns 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.
  - 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.
  - getCatalinaHome
```
File getCatalinaHome()
```
    Obtain the location of CATALINA_HOME.

Interface Container

Field Summary

Fields inherited from interface org.apache.catalina.Lifecycle

Method Summary

Methods inherited from interface org.apache.catalina.Lifecycle

Field Detail

ADD_CHILD_EVENT

ADD_VALVE_EVENT

REMOVE_CHILD_EVENT

REMOVE_VALVE_EVENT

Method Detail

getLogger

getObjectName

getDomain

getMBeanKeyProperties

getPipeline

getCluster

setCluster

getBackgroundProcessorDelay

setBackgroundProcessorDelay

getName

setName

getParent

setParent

getParentClassLoader

setParentClassLoader

getRealm

setRealm

backgroundProcess

addChild

addContainerListener

addPropertyChangeListener

findChild

findChildren

findContainerListeners

removeChild

removeContainerListener

removePropertyChangeListener

fireContainerEvent

logAccess

getAccessLog

getStartStopThreads

setStartStopThreads

getCatalinaBase

getCatalinaHome