mcconnell 02/02/20 20:36:35
Added: src/java/org/apache/avalon/framework/service
DefaultServiceManager.java ServiceException.java
ServiceManager.java ServiceSelector.java
Serviceable.java package.html
Log:
initial entry of Service package
Revision Changes Path
1.1
jakarta-avalon/src/java/org/apache/avalon/framework/service/DefaultServiceManager.java
Index: DefaultServiceManager.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.avalon.framework.service;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* This class is a static implementation of a ServiceManager. Allow ineritance
* and extension so you can generate a tree of ServiceManager each defining
* Object scope.
*
* @author <a href="mailto:[EMAIL PROTECTED]">Federico Barbieri</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Peter Donald</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stephen McConnell</a>
*/
public class DefaultServiceManager
implements ServiceManager
{
private final HashMap m_components = new HashMap();
private final ServiceManager m_parent;
private boolean m_readOnly;
/**
* Construct ServiceManager with no parent.
*
*/
public DefaultServiceManager()
{
this( null );
}
/**
* Construct ServiceManager with specified parent.
*
* @param parent the ServiceManager parent
*/
public DefaultServiceManager( final ServiceManager parent )
{
m_parent = parent;
}
/**
* Retrieve Object by role from ServiceManager.
*
* @param role the role
* @return the Object
* @exception ServiceException if an error occurs
*/
public Object lookup( final String role )
throws ServiceException
{
final Object component = m_components.get( role );
if( null != component )
{
return component;
}
else if( null != m_parent )
{
return m_parent.lookup( role );
}
else
{
throw new ServiceException( "Unable to provide implementation for
" + role );
}
}
public boolean hasService( final String role ) {
boolean componentExists = false;
try
{
this.lookup(role);
componentExists = true;
}
catch (Throwable t)
{
// Ignore all throwables--we want a yes or no answer.
}
return componentExists;
}
/**
* Place Component into ComponentManager.
*
* @param role the components role
* @param component the component
*/
public void put( final String role, final Object object )
{
checkWriteable();
m_components.put( role, object );
}
/**
* Build a human readable representation of ComponentManager2.
*
* @return the description of ComponentManager2
*/
public String toString()
{
final StringBuffer buffer = new StringBuffer();
final Iterator components = m_components.keySet().iterator();
buffer.append( "Services:" );
while( components.hasNext() )
{
buffer.append( "[" );
buffer.append( components.next() );
buffer.append( "]" );
}
return buffer.toString();
}
/**
* Helper method for subclasses to retrieve parent.
*
* @return the parent ServiceManager
*/
protected final ServiceManager getParent()
{
return m_parent;
}
/**
* Helper method for subclasses to retrieve component map.
*
* @return the component map
*/
protected final Map getComponentMap()
{
return m_components;
}
public void makeReadOnly()
{
m_readOnly = true;
}
protected final void checkWriteable()
throws IllegalStateException
{
if( m_readOnly )
{
throw new IllegalStateException( "ServiceManager is read only and
can not be modified" );
}
}
/**
* Release the object.
* @param object The <code>Object</code> to release.
*/
public void release( Object object ){}
}
1.1
jakarta-avalon/src/java/org/apache/avalon/framework/service/ServiceException.java
Index: ServiceException.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.avalon.framework.service;
import org.apache.avalon.framework.CascadingException;
/**
* The exception thrown to indicate a problem with service.
* It is usually thrown by ServiceManager or ServiceSelector.
*
* @author <a href="mailto:[EMAIL PROTECTED]">Peter Donald</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Pierpaolo Fumagalli</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Federico Barbieri</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stefano Mazzocchi</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stephen McConnell</a>
*/
public class ServiceException
extends CascadingException
{
/**
* Construct a new <code>ServiceException</code> instance.
*
* @param message the exception message
* @param throwable the throwable
*/
public ServiceException( final String message, final Throwable throwable )
{
super( message, throwable );
}
/**
* Construct a new <code>ServiceException</code> instance.
*
* @param message the exception message
*/
public ServiceException( final String message )
{
super( message, null );
}
}
1.1
jakarta-avalon/src/java/org/apache/avalon/framework/service/ServiceManager.java
Index: ServiceManager.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.avalon.framework.service;
/**
* A <code>ServiceManager</code> selects <code>Object</code>s based on a
* role. The contract is that all the <code>Object</code>s implement the
* differing roles and there is one <code>Object</code> per role. If you
* need to select on of many <code>Object</code>s that implement the same
* role, then you need to use a <code>ServiceSelector</code>. 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:
*
* <ul>
* <li> InputAdaptor and OutputAdaptor</li>
* <li> Store and Spool</li>
* </ul>
*
* The <code>ServiceManager</code> does not specify the methodology of
* getting the <code>Object</code>, merely the interface used to get it.
* Therefore the <code>ServiceManager</code> can be implemented with a
* factory pattern, an object pool, or a simple Hashtable.
*
* @see org.apache.avalon.framework.service.Serviceable
* @see org.apache.avalon.framework.service.ServiceSelector
*
* @author <a href="mailto:[EMAIL PROTECTED]">Federico Barbieri</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stefano Mazzocchi</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Pierpaolo Fumagalli</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Berin Loritsch</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stephen McConnell</a>
*/
public interface ServiceManager
{
/**
* Get the <code>Object</code> associated with the given role. For
* instance, If the <code>ServiceManager</code> had a
* <code>LoggerComponent</code> stored and referenced by role, I would use
* the following call:
* <pre>
* try
* {
* MyComponent log;
* myComponent = (MyComponent) manager.lookup(MyComponent.ROLE);
* }
* catch (...)
* {
* ...
* }
* </pre>
*
* @param name The role name of the <code>Object</code> to retrieve.
* @exception ServiceException if an error occurs
*/
Object lookup( String role )
throws ServiceException;
/**
* Check to see if a <code>Object</code> exists for a role.
*
* @param role a string identifying the role to check.
* @return True if the object exists, False if it does not.
*/
boolean hasService( String role );
/**
* Return the <code>Object</code> when you are finished with it. This
* allows the <code>ServiceManager</code> to handle the End-Of-Life
Lifecycle
* events associated with the <code>Object</code>. 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.
*
* @param object The <code>Object</code> we are releasing.
*/
void release( Object object );
}
1.1
jakarta-avalon/src/java/org/apache/avalon/framework/service/ServiceSelector.java
Index: ServiceSelector.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.avalon.framework.service;
/**
* A <code>ServiceSelector</code> selects <code>Object</code>s based on a
* supplied policy. The contract is that all the <code>Object</code>s
implement the
* same role.
*
* @see org.apache.avalon.framework.service.Serviceable
* @see org.apache.avalon.framework.service.ServiceManager
*
* @author <a href="mailto:[EMAIL PROTECTED]">Berin Loritsch</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stephen McConnell</a>
*/
public interface ServiceSelector
{
/**
* Select the <code>Object</code> associated with the given policy.
* For instance, If the <code>ServiceSelector</code> has a
* <code>Generator</code> stored and referenced by a URL, I would use the
* following call:
*
* <pre>
* try
* {
* Generator input;
* input = (Generator)selector.select( new URL("foo://demo/url") );
* }
* catch (...)
* {
* ...
* }
* </pre>
*
* @param policy A criteria against which a <code>Object</code> is
selected.
*
* @exception ServiceSelector If the requested <code>Object</code> cannot
be supplied
*/
Object select( Object policy )
throws ServiceException;
/**
* Check to see if a <code>Object</code> exists relative to the supplied
policy.
*
* @param policy a <code>Object</code> containing the selection criteria
* @return True if the component is available, False if it not.
*/
boolean isSelectable( Object policy );
/**
* Return the <code>Object</code> when you are finished with it. This
* allows the <code>ServiceSelector</code> to handle the End-Of-Life
Lifecycle
* events associated with the <code>Object</code>. 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.
*
* @param object The <code>Object</code> we are releasing.
*/
void release( Object object );
}
1.1
jakarta-avalon/src/java/org/apache/avalon/framework/service/Serviceable.java
Index: Serviceable.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.avalon.framework.service;
/**
* A servicable is a class that need to connect to software components using
* a "role" abstraction, thus not depending on particular implementations
* but on behavioral interfaces.
* <br />
*
* The contract surrounding a <code>Serviceable</code> is that it is a user.
* The <code>Serviceable</code> is able to use <code>Object</code>s managed
* by the <code>ServiceManager</code> it was initialized with. As part
* of the contract with the system, the instantiating entity must call
* the <code>compose</code> method before the <code>Serviceable</code>
* can be considered valid.
*
* @see org.apache.avalon.framework.service.ServiceManager
* @see org.apache.avalon.framework.service.ServiceResolver
*
* @author <a href="mailto:[EMAIL PROTECTED]">Federico Barbieri</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Pierpaolo Fumagalli</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stefano Mazzocchi</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Berin Loritsch</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Stephen McConnell</a>
*/
public interface Serviceable
{
/**
* Pass the <code>ServiceManager</code> to the <code>servicable</code>.
* The <code>Servicable</code> implementation should use the specified
* <code>ServiceManager</code> to acquire the components it needs for
* execution.
*
* @param manager The <code>ServiceManager</code> which this
* <code>Servicable</code> uses.
*/
void service( ServiceManager manager )
throws ServiceException;
}
1.1
jakarta-avalon/src/java/org/apache/avalon/framework/service/package.html
Index: package.html
===================================================================
<body>
Interfaces and default implementation of a service management framework
supporting container based service lookup and decommissioning.
</body>
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