/*
* 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.avalon.phoenix.components.manager;
import java.util.HashMap;
import org.apache.avalon.excalibur.i18n.ResourceManager;
import org.apache.avalon.excalibur.i18n.Resources;
import org.apache.avalon.phoenix.interfaces.ManagerException;
import org.apache.avalon.phoenix.interfaces.SystemManager;
/**
* Implements a management context local to a particular process with which
* it can register its managed object. The naming scheme that results is
* meant to be compatible with jmx.
*
* @author <a href="mailto:huw@apache.org">Huw Roberts</a>
*/
class SubContext
implements SystemManager
{
private static final Resources REZ =
ResourceManager.getPackageResources( SubContext.class );
private static final String EMPTY_STRING = "";
private final HashMap m_subcontexts = new HashMap();
private final SystemManager m_parent;
private final String m_name;
private final String m_type;
/**
* Creates new SubContext to the specified context. Objects registered
* under the subcontext will be typed with the name of the context so the
* jmx name becomes 'contextName' + 'objectNameSoFar'
*
* @param parent the parent context
* @param name the subcontext name
*/
public SubContext( final SystemManager parent,
final String name,
final String type )
{
if( null == parent )
{
throw new NullPointerException( "parent" );
}
m_parent = parent;
m_name = name;
m_type = type;
}
/**
* Register an object for management.
* The object is exported through some management scheme
* (typically JMX) and the management is restricted
* to the interfaces passed in as a parameter to method.
*
* @param name the name to register object under
* @param object the object
* @param interfaces the interfaces to register the component under
* @throws ManagerException if an error occurs. An error could occur if the object doesn't
* implement the interfaces, the interfaces parameter contain non-instance
* classes, the name is already registered etc.
* @throws IllegalArgumentException if object or interfaces is null
*/
public void register( String name, Object object, Class[] interfaces )
throws ManagerException, IllegalArgumentException
{
m_parent.register( jmxName( name ), object, interfaces );
}
/**
* Register an object for management.
* The object is exported through some management scheme
* (typically JMX). Note that the particular management scheme
* will most likely use reflection to extract manageable information.
*
* @param name the name to register object under
* @param object the object
* @throws ManagerException if an error occurs such as name already registered.
* @throws IllegalArgumentException if object is null
*/
public void register( String name, Object object )
throws ManagerException, IllegalArgumentException
{
m_parent.register( jmxName( name ), object );
}
/**
* Unregister named object.
*
* @param name the name of object to unregister
* @throws ManagerException if an error occurs such as when no such object registered.
*/
public void unregister( String name )
throws ManagerException
{
m_parent.unregister( jmxName( name ) );
}
/**
* Returns the subcontext of the specified name. If it does not exist it
* is created.
*
* @return the subcontext with the specified name
* @throws ManagerException if context cannot be created or retrieved
*/
public SystemManager getSubContext( final String name,
final String type )
throws ManagerException
{
if( null == type || EMPTY_STRING.equals( type ) )
{
final String message =
REZ.getString( "subcontext.error.no.subcontext" );
throw new ManagerException( message );
}
else if( null != name && this.m_type == null )
{
final String message =
REZ.getString( "subcontext.error.no.subcontext" );
throw new ManagerException( message );
}
// get from list if possible
final String key = contextKey( name, type );
SystemManager subcontext =
(SystemManager)m_subcontexts.get( key );
// otherwise create and add to list
if( subcontext == null )
{
subcontext = new SubContext( this, name, type );
m_subcontexts.put( key, subcontext );
}
return subcontext;
}
/**
* Helper method used to generate the jmx name by appending the current name
* and passing up the chain to the root context
*/
private String jmxName( final String name )
{
final StringBuffer sb = new StringBuffer();
if( null != m_name )
{
sb.append( m_name );
sb.append( ',' );
}
if( null != m_type )
{
sb.append( m_type );
sb.append( '=' );
}
sb.append( name );
return sb.toString();
}
/**
* Helper method to get key used to store subcontexts
* in m_subcontexts
*/
private String contextKey( final String parent,
final String type )
{
return parent + "|" + type;
}
}