org.apache.avalon.framework.service
Interface ServiceManager

All Known Implementing Classes:

DefaultServiceManager, FortressServiceManager, NoopServiceManager, WrapperServiceManager

public interface ServiceManager

A ServiceManager selects Objects based on a role. The contract is that all the Objects implement the differing roles and there is one Object per role. If you need to select on of many Objects that implement the same role, then you need to use a ServiceSelector. 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 ServiceManager does not specify the methodology of getting the Object, merely the interface used to get it. Therefore the ServiceManager can be implemented with a factory pattern, an object pool, or a simple Hashtable.

Version:

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

Author:

Avalon Development Team

See Also:

Serviceable, ServiceSelector

Method Summary

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

Method Detail

lookup

public java.lang.Object lookup(java.lang.String key)
                        throws ServiceException

Get the Object associated with the given key. For instance, If the ServiceManager had a LoggerComponent stored and referenced by key, the following could be used:

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

Parameters:

key - The lookup key of the Object to retrieve.

Returns:

an Object value

Throws:

ServiceException - if an error occurs

hasService

public boolean hasService(java.lang.String key)

Check to see if a Object exists for a key.

Parameters:

key - a string identifying the key to check.

Returns:

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

release

public void release(java.lang.Object object)

Return the Object when you are finished with it. This allows the ServiceManager 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 ServiceManager system without having to trap Exceptions on a release.

Parameters:

object - The Object we are releasing, may also be a null reference