org.apache.avalon.framework.component
Interface ComponentManager

All Known Implementing Classes:

DefaultComponentManager, ExcaliburComponentManager, WrapperComponentManager

public interface ComponentManager

A ComponentManager selects Components based on a role. The contract is that all the Components implement the differing roles and there is one Component per role. If you need to select on of many Components that implement the same role, then you need to use a ComponentSelector. Roles are usually the full interface name.

A role is better understood by the analogy of a play. There are many different roles in a script. Any actor or actress can play any given part and you get the same results (phrases said, movements made, etc.). The exact nuances of the performance is different.

Below is a list of things that might be considered the different roles:

• InputAdapter and OutputAdapter
• Store and Spool

The ComponentManager does not specify the methodology of getting the Component, merely the interface used to get it. Therefore the ComponentManager can be implemented with a factory pattern, an object pool, or a simple Hashtable.

Deprecated: Use ServiceManager instead.

Version:

$Id: ComponentManager.java 30977 2004-07-30 08:57:54Z niclas $

Author:

Avalon Development Team

See Also:

Component, Composable, ComponentSelector

Method Summary

boolean	hasComponent(java.lang.String key) Check to see if a Component exists for a key.
Component	lookup(java.lang.String key) Get the Component associated with the given key.
void	release(Component component) Return the Component when you are finished with it.

Method Detail

lookup

public Component lookup(java.lang.String key)
                 throws ComponentException

Get the Component associated with the given key. For instance, If the ComponentManager had a LoggerComponent stored and referenced by key, I would use the following call:

 try
 {
     LoggerComponent log;
     myComponent = (LoggerComponent) m_manager.lookup(LoggerComponent.ROLE);
 }
 catch (...)
 {
     ...
 }
 

Parameters:

key - The key name of the Component to retrieve.

Returns:

the desired component

Throws:

ComponentException - if an error occurs

hasComponent

public boolean hasComponent(java.lang.String key)

Check to see if a Component exists for a key.

Parameters:

key - a string identifying the key to check.

Returns:

True if the component exists, False if it does not.

release

public void release(Component component)

Return the Component when you are finished with it. This allows the ComponentManager to handle the End-Of-Life Lifecycle events associated with the Component. Please note, that no Exceptions should be thrown at this point. This is to allow easy use of the ComponentManager system without having to trap Exceptions on a release.

Parameters:

component - The Component we are releasing.