plugins/org.eclipse.wst.server.core/servercore/org/eclipse/wst/server/core/model/ServerDelegate.java

/**********************************************************************
 * Copyright (c) 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 *
 * Contributors:
 *     IBM Corporation - Initial API and implementation
 **********************************************************************/
package org.eclipse.wst.server.core.model;

import java.util.List;
import java.util.Map;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.wst.server.core.IModule;
import org.eclipse.wst.server.core.IRuntime;
import org.eclipse.wst.server.core.IServer;
import org.eclipse.wst.server.core.IServerPort;
import org.eclipse.wst.server.core.IServerWorkingCopy;
import org.eclipse.wst.server.core.internal.Server;
import org.eclipse.wst.server.core.internal.ServerWorkingCopy;
/**
 * A server delegate provides the implementation for various 
 * generic and server-type-specific operations for a specific type of server.
 * A server delegate is specified by the
 * <code>class</code> attribute of a <code>serverTypes</code> extension.
 * <p>
 * When the server instance needs to be given a delegate, the delegate class
 * specified for the server type is instantiated with a 0-argument constructor
 * and primed with <code>delegate.initialize(((IServerState)server)</code>, 
 * which it is expected to hang on to. Later, when
 * <code>delegate.dispose()</code> is called as the server instance is
 * being discarded, the delegate is expected to let go of the server instance.
 * </p>
 * <p>
 * Server delegates may keep state in instance fields, but that state is
 * transient and will not be persisted across workbench sessions. To save
 * state across workbench sessions, it must be persisted using the
 * attributes.
 * </p>
 * <p>
 * This abstract class is intended to be extended only by clients
 * to extend the <code>serverTypes</code> extension point.
 * </p>
 * <p>
 * <it>Caveat: The server core API is still in an early form, and is
 * likely to change significantly before the initial release.</it>
 * </p>
 * 
 * @see IServer
 * @see IServerWorkingCopy
 * @since 1.0
 */
public abstract class ServerDelegate {
	private Server server;
	private ServerWorkingCopy serverWC;

	/**
	 * Delegates must have a public 0-arg constructor.
	 */
	public ServerDelegate() {
		// do nothing
	}

	/**
	 * Initializes this server delegate with its life-long server instance.
	 * <p>
	 * This method is called by the server core framework.
	 * Clients should never call this method.
	 * </p>
	 * 
	 * @param server the server instance
	 */
	public final void initialize(Server newServer) {
		server = newServer;
		if (newServer instanceof ServerWorkingCopy)
			serverWC = (ServerWorkingCopy) newServer;
		initialize();
	}

	/**
	 * Initializes this server delegate. This method gives delegates a chance
	 * to do their own initialization.
	 * <p>
	 * This method is called by the server core framework.
	 * Clients should never call this method.
	 * </p>
	 */
	public void initialize() {
		// do nothing
	}

	/**
	 * Returns the server that this server delegate corresponds to.
	 * 
	 * @return the server
	 */
	public final IServer getServer() {
		return server;
	}

	/**
	 * Returns the server working copy that this server delegate corresponds to.
	 * 
	 * @return the server
	 */
	public final IServerWorkingCopy getServerWorkingCopy() {
		return serverWC;
	}

	public final int getAttribute(String attributeName, int defaultValue) {
		return server.getAttribute(attributeName, defaultValue);
	}

	public final boolean getAttribute(String attributeName, boolean defaultValue) {
		return server.getAttribute(attributeName, defaultValue);
	}
	
	public final String getAttribute(String attributeName, String defaultValue) {
		return server.getAttribute(attributeName, defaultValue);
	}

	public final List getAttribute(String attributeName, List defaultValue) {
		return server.getAttribute(attributeName, defaultValue);
	}

	public final Map getAttribute(String attributeName, Map defaultValue) {
		return server.getAttribute(attributeName, defaultValue);
	}

	/**
	 * Disposes of this server delegate.
	 * <p>
	 * This method is called by the web server core framework.
	 * Clients should never call this method.
	 * </p>
	 * <p>
	 * Implementations are expected to let go of the delegate's reference
	 * to the server, deregister listeners, etc.
	 * </p>
	 */
	public void dispose() {
		// do nothing
	}

	/**
	 * Returns whether the specified module modifications could be made to this
	 * server at this time. See the specification of
	 * {@link IServer#canModifyModules(IModule[], IModule[])}
	 * for further details. 
	 * <p>
	 * This method is called by the web server core framework,
	 * in response to a call to <code>IServer.canModifyModules</code>.
	 * Clients should never call this method.
	 * </p>
	 * <p>
	 * [issue: See IServer.canModifyModules(IModule[], IModule[]).]
	 * </p>
	 *
	 * @param add a possibly-empty list of modules to add
	 * @param remove a possibly-empty list of modules to remove
	 * @param monitor a progress monitor, or <code>null</code> if progress
	 *    reporting and cancellation are not desired
	 * @return <code>true</code> if the proposed modifications
	 * look feasible, and <code>false</code> otherwise
	 * Returns true if this module can be added to this
	 * configuration at the current time, and false otherwise.
	 */
	public abstract IStatus canModifyModules(IModule[] add, IModule[] remove);

	/**
	 * Returns the list of modules that are associated with
	 * this server. See the specification of
	 * {@link IServer#getModules()} for further details. 
	 * <p>
	 * This method is called by the web server core framework,
	 * in response to a call to <code>IServer.getModules</code>.
	 * Clients should never call this method.
	 * </p>
	 * <p>
	 * [issue: Where does the delegate get these objects from,
	 * especially at the start of a follow-on session?]
	 * </p>
	 *
	 * @return a possibly-empty list of modules
	 */
	public abstract IModule[] getModules();

	/**
	 * Returns the child module(s) of this module. If this
	 * module contains other modules, it should list those
	 * modules. If not, it should return an empty list.
	 *
	 * <p>This method should only return the direct children.
	 * To obtain the full module tree, this method may be
	 * recursively called on the children.</p>
	 *
	 * @see IServer#getChildModules(IModule)
	 */
	public abstract IModule[] getChildModules(IModule module);

	/**
	 * Returns the parent module(s) of this module. When
	 * determining if a given project can run on a server
	 * configuration, this method will be used to find the
	 * actual module(s) that may be run on the server. For
	 * instance, a Web module may return a list of Ear
	 * modules that it is contained in if the server only
	 * supports configuring Ear modules.
	 *
	 * <p>If the module type is not supported, this method
	 * may return null. If the type is normally supported but there
	 * is a configuration problem or missing parent, etc., this
	 * method may fire a CoreException that may then be presented
	 * to the user.</p>
	 *
	 * <p>If it does return valid parent(s), this method should
	 * always return the topmost parent module(s), even if
	 * there are a few levels (a heirarchy) of modules.</p>
	 *
	 * @see IServer#getParentModules(IModule)
	 */
	public abstract IModule[] getParentModules(IModule module) throws CoreException;
	
	/**
	 * Returns an array of IServerPorts that this server has.
	 *
	 * @return the server's ports
	 */
	public IServerPort[] getServerPorts() {
		return null;
	}

	/**
	 * Initializes this server with default values. This method is called when
	 * a new server is created so that the server can be initialized with
	 * meaningful values.
	 */
	public void setDefaults() {
		// do nothing
	}
	
	/**
	 * Sets the value of the specified integer-valued attribute of this
	 * element.
	 * 
	 * @param id the attribute id
	 * @param value the value of the specified attribute
	 * @see getAttribute(String, int)
	 */
	public final void setAttribute(String id, int value) {
		serverWC.setAttribute(id, value);
	}

	/**
	 * Sets the value of the specified boolean-valued attribute of this
	 * element.
	 * 
	 * @param id the attribute id
	 * @param value the value of the specified attribute
	 * @see getAttribute(String, boolean)
	 */
	public final void setAttribute(String id, boolean value) {
		serverWC.setAttribute(id, value);
	}

	/**
	 * Sets the value of the specified string-valued attribute of this
	 * element.
	 * 
	 * @param id the attribute id
	 * @param value the value of the specified attribute
	 * @see getAttribute(String, String)
	 */
	public final void setAttribute(String id, String value) {
		serverWC.setAttribute(id, value);
	}

	/**
	 * Sets the value of the specified list-valued attribute of this
	 * element. The list may only contain String values.
	 * 
	 * @param id the attribute id
	 * @param value the value of the specified attribute
	 * @see getAttribute(String, List)
	 */
	public final void setAttribute(String id, List value) {
		serverWC.setAttribute(id, value);
	}

	/**
	 * Sets the value of the specified map-valued attribute of this
	 * element. The map may only contain String values.
	 * 
	 * @param id the attribute id
	 * @param value the value of the specified attribute
	 * @see getAttribute(String, Map)
	 */
	public final void setAttribute(String id, Map value) {
		serverWC.setAttribute(id, value);
	}

	/**
	 * Modifies the list of modules associated with the server.
	 * See the specification of
	 * {@link IServerWorkingCopy#modifyModules(IModule[], IModule[], IProgressMonitor)}
	 * for further details.
	 * <p>
	 * This method is called by the web server core framework,
	 * in response to a call to <code>IServerWorkingCopy.modifyModules</code>.
	 * Clients should never call this method.
	 * </p>
	 *
	 * @param add a possibly-empty list of modules to add
	 * @param remove a possibly-empty list of modules to remove
	 * @param monitor a progress monitor, or <code>null</code> if progress
	 *    reporting and cancellation are not desired
	 * @throws CoreException [missing]
	 */
	public abstract void modifyModules(IModule[] add, IModule[] remove, IProgressMonitor monitor) throws CoreException;

	/**
	 * Returns true if this is a configuration that is
	 * applicable to (can be used with) this server.
	 *
	 * @param configuration
	 * @return boolean
	 */
	public boolean isSupportedConfiguration(IPath configuration2) {
		return true;
	}

	public void importConfiguration(IRuntime runtime, IProgressMonitor monitor) {
		// do nothing
	}

	public void saveConfiguration(IProgressMonitor monitor) throws CoreException {
		// do nothing
	}
}