bloritsch 2002/09/09 08:25:22
Added: container/src/java/org/apache/excalibur/container/lookup
AbstractServiceManager.java
Log:
add the abstract ServiceManager that allows resolution against a public JNDI bound
service
Revision Changes Path
1.1
jakarta-avalon-excalibur/container/src/java/org/apache/excalibur/container/lookup/AbstractServiceManager.java
Index: AbstractServiceManager.java
===================================================================
/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software License
* version 1.1, a copy of which has been included with this distribution in
* the LICENSE.txt file.
*/
package org.apache.excalibur.container.lookup;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.ServiceException;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
/**
* Abstract implementation of a <code>ServiceManager</code>. This will
* make it easier to implement ServiceManagers that use exposed management
* services, as well as respect the hierarchical nature of ServiceManagers.
*
* @author <a href="mailto:[EMAIL PROTECTED]";>Berin Loritsch</a>
*/
public abstract class AbstractServiceManager implements ServiceManager
{
private final ServiceManager m_parent;
private final Context m_context;
public AbstractServiceManager()
{
this( null, null );
}
public AbstractServiceManager( ServiceManager parent )
{
this( parent, null );
}
public AbstractServiceManager( ServiceManager parent, Context initContext )
{
m_parent = parent;
Context checkContext = initContext;
if ( null == checkContext )
{
// If there is a public context for services use it.
try
{
checkContext = new InitialContext();
}
catch ( NamingException ne )
{
checkContext = null;
}
}
m_context = checkContext;
}
protected abstract boolean serviceExists( String role );
protected abstract Object obtainService( String role );
public abstract void release( Object service );
/**
* The logic for testing if a service exists. First we test ourselves,
* second we test the parent ServiceManager if it exists, and lastly
* we test the JNDI context if it exists.
*/
public boolean hasService( String role )
{
boolean exists = serviceExists( role );
if ( ! exists && null != m_parent )
{
exists = m_parent.hasService( role );
}
if ( ! exists && null != m_context )
{
exists = ( null == obtainServiceFromJNDI( role ) );
}
return exists;
}
/**
* The logic for obtaining a service from a ServiceManager. First we
* try to get it from this ServiceManager, then we try to get it from the
* parent manager. If it exists, we will lastly try the JNDI context.
*/
public Object lookup( String role )
throws ServiceException
{
Object service = obtainService( role );
if ( null == service && null != m_parent )
{
service = obtainServiceFromParent( role );
}
if ( null == service && null != m_context )
{
service = obtainServiceFromJNDI( role );
}
if ( null == service )
{
throw new ServiceException( role, "Service does not exist." );
}
return service;
}
/**
* Grabs the service from the parent. If it does not exist, we
* don't even try.
*/
protected Object obtainServiceFromParent( String role )
{
Object service = null;
if ( m_parent.hasService( role ) )
{
try
{
service = m_parent.lookup( role );
}
catch ( ServiceException se )
{
// ignore, it is already null
}
}
return service;
}
/**
* Grabs the service from the JNDI role. Unfortunately, there is
* no way to test the context before we grab it. As a result we
* have to incur the overhead of a lookup/exception if it is not
* bound.
*/
protected Object obtainServiceFromJNDI( String role )
{
Object service = null;
try
{
service = m_context.lookup( role );
}
catch ( NamingException se )
{
// ignore, it is already null
}
return service;
}
}
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