org.apache.avalon.framework.service

Interface ServiceSelector

Known Implementing Classes:
DefaultServiceSelector, WrapperServiceSelector

public interface ServiceSelector

A ServiceSelector selects Objects based on a supplied policy. The contract is that all the Objects implement the same role.

Version:
CVS $Revision: 1.13 $ $Date: 2003/02/11 15:58:42 $

Author:
Avalon Development Team

See Also:
Serviceable, ServiceSelector

Method Summary

boolean
isSelectable(Object policy)
Check to see if a Object exists relative to the supplied policy.
void
release(Object object)
Return the Object when you are finished with it.
Object
select(Object policy)
Select the Object associated with the given policy.

Method Details

isSelectable

public boolean isSelectable(Object policy)
Check to see if a Object exists relative to the supplied policy.

Parameters:
policy - a Object containing the selection criteria

Returns:
True if the component is available, False if it not.


release

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

Parameters:
object - The Object we are releasing.


select

public Object select(Object policy)
            throws ServiceException
Select the Object associated with the given policy. For instance, If the ServiceSelector has a Generator stored and referenced by a URL, the following call could be used:
 try
 {
     Generator input;
     input = (Generator)selector.select( new URL("foo://demo/url") );
 }
 catch (...)
 {
     ...
 }
 

Parameters:
policy - A criteria against which a Object is selected.

Returns:
an Object value

Throws:
ServiceException - If the requested Object cannot be supplied


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