org.apache.avalon.framework.service
Interface ServiceManager
public interface ServiceManager
A
ServiceManager
selects
Object
s based on a
role. The contract is that all the
Object
s implement the
differing roles and there is one
Object
per role. If you
need to select on of many
Object
s 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.
CVS $Revision: 1.17 $ $Date: 2004/02/11 14:34:25 $ boolean | hasService(String key) - Check to see if a
Object exists for a key.
|
Object | lookup(String key) - Get the
Object associated with the given key.
|
void | release(Object object) - Return the
Object when you are finished with it.
|
hasService
public boolean hasService(String key)
Check to see if a Object
exists for a key.
key
- a string identifying the key to check.
- True if the object exists, False if it does not.
lookup
public Object lookup(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 (...)
{
...
}
key
- The lookup key of the Object
to retrieve.
release
public void release(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.
object
- The Object
we are releasing, may also be
a null
reference