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/*
* This file is part of the Echo Web Application Framework (hereinafter "Echo").
* Copyright (C) 2002-2009 NextApp, Inc.
*
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*/
package nextapp.echo.app.update;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import nextapp.echo.app.ApplicationInstance;
import nextapp.echo.app.Command;
import nextapp.echo.app.Component;
/**
* Monitors updates to component hierarchy and records deltas between
* server state of application and client state of application.
*/
public class ServerUpdateManager
implements Serializable {
/** Serial Version UID. */
private static final long serialVersionUID = 20070101L;
/**
* Comparator to sort components by their depth in the
* hierarchy.
*/
private static final Comparator hierarchyDepthUpdateComparator = new Comparator() {
/**
* @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
*/
public int compare(Object a, Object b) {
return getDepth(((ServerComponentUpdate) a).getParent()) - getDepth(((ServerComponentUpdate) b).getParent());
}
/**
* @see java.lang.Object#equals(java.lang.Object)
*/
public boolean equals(Object o) {
return false;
}
/**
* Returns the depth of the specified component in the hierarchy.
*
* @param component the component
* @return the depth
*/
private int getDepth(Component component) {
int count = 0;
while (component != null) {
component = component.getParent();
++count;
}
return count;
}
};
/** Empty array of commands. */
private static final Command[] EMPTY_COMMAND_ARRAY = new Command[0];
/** Map between application property names and PropertyUpdates to the application. */
private Map applicationUpdateMap;
/** Enqueued commands to be executed. */
private List commands;
/**
* Map between Components and ServerComponentUpdates. The key is the parent component involved in
* the update.
*/
private Map componentUpdateMap;
/** Special ServerComponentUpdate used to describe a full-refresh of the application state being required. */
private ServerComponentUpdate fullRefreshUpdate;
/** The ClientUpdateManager that will be used to process input from the client. */
private ClientUpdateManager clientUpdateManager;
/** The updating ApplicationInstance. */
private ApplicationInstance applicationInstance;
/** Cache of ServerComponentUpdates (returned by multiple invocations of getComponentUpdates().) */
private ServerComponentUpdate[] cachedComponentUpdates;
/**
* Creates a new ServerUpdateManager.
*
* Warning: the init() method must be
* invoked before the ServerUpdateManager is used.
*
* @param applicationInstance the relevant ApplicationInstance
* @see #init(nextapp.echo.app.update.ClientUpdateManager)
*/
public ServerUpdateManager(ApplicationInstance applicationInstance) {
super();
this.applicationInstance = applicationInstance;
applicationUpdateMap = new HashMap();
componentUpdateMap = new HashMap();
fullRefreshUpdate = new ServerComponentUpdate(null);
}
/**
* Creates or retrieves a ComponentUpdate for the given
* parent component. If a ComponentUpdate is created, it
* is automatically stored in the update queue.
*
* @param parent the parent component of the update, i.e., the component
* which has had children added, removed, or its properties updated
* @return the created or retrieved update
*/
private ServerComponentUpdate createComponentUpdate(Component parent) {
ServerComponentUpdate update;
if (componentUpdateMap.containsKey(parent)) {
update = (ServerComponentUpdate) componentUpdateMap.get(parent);
} else {
update = new ServerComponentUpdate(parent);
componentUpdateMap.put(parent, update);
}
return update;
}
/**
* Enqueues a Command for processing.
*
* @param command the command
*/
public void enqueueCommand(Command command) {
if (commands == null) {
commands = new ArrayList();
}
commands.add(command);
}
/**
* Returns a PropertyUpdate representing the
* application-level property update with the specified name.
* If the specified property has not been updated, null is returned.
*
* @param propertyName the name of the property
* @return the PropertyUpdate
*/
public PropertyUpdate getApplicationPropertyUpdate(String propertyName) {
return (PropertyUpdate) applicationUpdateMap.get(propertyName);
}
/**
* Returns the stored Commands. The commands
* are NOT removed or modified by this call.
*
* @return the commands
*/
public Command[] getCommands() {
if (commands == null) {
return EMPTY_COMMAND_ARRAY;
} else {
return (Command[])commands.toArray(new Command[commands.size()]);
}
}
/**
* Returns the stored ServerComponentUpdates. The updates
* are NOT removed or modified by this call. The updates will be returned
* sorted by depth of their parent components within the hierarchy, but in
* otherwise random order.
*
* @return the updates
*/
public ServerComponentUpdate[] getComponentUpdates() {
if (isFullRefreshRequired()) {
return new ServerComponentUpdate[]{fullRefreshUpdate};
} else {
if (cachedComponentUpdates == null) {
Collection hierarchyUpdates = componentUpdateMap.values();
cachedComponentUpdates = (ServerComponentUpdate[])
hierarchyUpdates.toArray(new ServerComponentUpdate[hierarchyUpdates.size()]);
Arrays.sort(cachedComponentUpdates, hierarchyDepthUpdateComparator);
return cachedComponentUpdates;
} else {
return cachedComponentUpdates;
}
}
}
/**
* Initialization life-cycle method. Must be invoked before using
* the ServerUpdateManager.
*
* @param clientUpdateManager the ClientUpdateManager that
* will be used to process input from the client
*/
public void init(ClientUpdateManager clientUpdateManager) {
this.clientUpdateManager = clientUpdateManager;
}
/**
* Determines if an ancestor of the given component is being added.
*
* @param component the Component to investigate
* @return true if an ancestor of the component is being added
*/
private boolean isAncestorBeingAdded(Component component) {
Component child = component;
Component parent = component.getParent();
while (parent != null) {
ServerComponentUpdate update = (ServerComponentUpdate) componentUpdateMap.get(parent);
if (update != null) {
if (update.hasAddedChild(child)) {
return true;
}
}
child = parent;
parent = parent.getParent();
}
return false;
}
/**
* Determines if the manager has no updates.
*
* @return true if the manager has no updates
*/
public boolean isEmpty() {
return componentUpdateMap.size() == 0;
}
/**
* Determines if a full refresh of the client state is required.
*
* @return true if a full refresh is required
*/
public boolean isFullRefreshRequired() {
return fullRefreshUpdate != null;
}
/**
* Processes an update to a property of the ApplicationInstance.
*
* @param propertyName the name of the property
* @param oldValue the previous value of the property
* @param newValue the current value of the property
*/
public void processApplicationPropertyUpdate(String propertyName, Object oldValue, Object newValue) {
Object clientValue = clientUpdateManager.getApplicationUpdatePropertyValue(propertyName);
if (clientValue == newValue || (clientValue != null && clientValue.equals(newValue))) {
// New value is same as client value, thus client is already in sync: cancel the update.
applicationUpdateMap.remove(propertyName);
} else {
applicationUpdateMap.put(propertyName, new PropertyUpdate(oldValue, newValue));
}
}
/**
* Processes the addition of a component to the hierarchy.
* Creates/updates a ServerComponentUpdate if required.
*
* @param parent a component which currently exists in the hierarchy
* @param child the component which was added to parent
*/
public void processComponentAdd(Component parent, Component child) {
if (isFullRefreshRequired()) {
return;
}
if (!child.isRenderVisible()) {
return;
}
if (isAncestorBeingAdded(child)) {
return;
}
cachedComponentUpdates = null;
ServerComponentUpdate update = createComponentUpdate(parent);
update.addChild(child);
}
/**
* Processes an update to the LayoutData of a component.
* Creates/updates a ServerComponentUpdate if required.
*
* @param updatedComponent a component which currently exists in the
* hierarchy whose LayoutData has changed
*/
public void processComponentLayoutDataUpdate(Component updatedComponent) {
if (isFullRefreshRequired()) {
return;
}
if (!updatedComponent.isRenderVisible()) {
return;
}
cachedComponentUpdates = null;
Component parentComponent = updatedComponent.getParent();
if (parentComponent == null || isAncestorBeingAdded(parentComponent)) {
// Do nothing.
return;
}
ServerComponentUpdate update = createComponentUpdate(parentComponent);
update.updateLayoutData(updatedComponent);
}
/**
* Processes an update to a property of a component (other than the
* LayoutData property).
* Creates/updates a ServerComponentUpdate if required.
*
* @param updatedComponent the component whose property(s) changed.
* @param propertyName the name of the changed property
* @param oldValue The previous value of the property
* @param newValue The new value of the property
*/
public void processComponentPropertyUpdate(Component updatedComponent, String propertyName, Object oldValue, Object newValue) {
if (isFullRefreshRequired()) {
return;
}
if (!updatedComponent.isRenderVisible()) {
return;
}
if (isAncestorBeingAdded(updatedComponent)) {
return;
}
cachedComponentUpdates = null;
// Do not add update (and if necessary cancel any update) if the property is being updated
// as the result of input from the client (and thus client and server state of property are
// already synchronized).
ClientComponentUpdate clientComponentUpdate = clientUpdateManager.getComponentUpdate(updatedComponent);
if (clientComponentUpdate != null) {
if (clientComponentUpdate.hasInput(propertyName)) {
Object inputValue = clientComponentUpdate.getInputValue(propertyName);
if (inputValue == newValue || (inputValue != null && inputValue.equals(newValue))) {
ServerComponentUpdate update = (ServerComponentUpdate) componentUpdateMap.get(updatedComponent);
if (update != null) {
update.cancelUpdateProperty(propertyName);
}
return;
}
}
}
ServerComponentUpdate update = createComponentUpdate(updatedComponent);
update.updateProperty(propertyName, oldValue, newValue);
}
/**
* Processes the removal of a component from the hierarchy.
* Creates/updates a ServerComponentUpdate if required.
*
* @param parent a component which currently exists in the hierarchy
* @param child the component which was removed from parent
*/
public void processComponentRemove(Component parent, Component child) {
if (isFullRefreshRequired()) {
return;
}
if (!parent.isRenderVisible()) {
return;
}
if (isAncestorBeingAdded(parent)) {
return;
}
cachedComponentUpdates = null;
ServerComponentUpdate update = createComponentUpdate(parent);
update.removeChild(child);
// Search updated components for descendants of removed component.
// Any found descendants will be removed and added to this update's
// list of removed descendants.
Iterator it = componentUpdateMap.keySet().iterator();
while (it.hasNext()) {
Component testComponent = (Component) it.next();
if (child.isAncestorOf(testComponent)) {
ServerComponentUpdate childUpdate = (ServerComponentUpdate) componentUpdateMap.get(testComponent);
update.appendRemovedDescendants(childUpdate);
it.remove();
}
}
}
/**
* Processes an update to the visible state of a component.
* Creates/updates a ServerComponentUpdate if required.
*
* @param updatedComponent a component which currently exists in the
* hierarchy whose visible state has changed.
*/
public void processComponentVisibilityUpdate(Component updatedComponent) {
cachedComponentUpdates = null;
Component parentComponent = updatedComponent.getParent();
if (updatedComponent.isVisible()) {
processComponentAdd(parentComponent, updatedComponent);
} else {
processComponentRemove(parentComponent, updatedComponent);
}
}
/**
* Processes a full refresh of the application state, in response to a
* severe change, such as application locale or style sheet.
*/
public void processFullRefresh() {
if (fullRefreshUpdate != null) {
return;
}
cachedComponentUpdates = null;
fullRefreshUpdate = new ServerComponentUpdate(null);
if (applicationInstance.getDefaultWindow() != null) {
// Default window may be null if an operation is invoked from within the
// ApplicationInstsance.init() implementation that causes a full refresh.
fullRefreshUpdate.removeDescendant(applicationInstance.getDefaultWindow());
}
Iterator it = componentUpdateMap.keySet().iterator();
while (it.hasNext()) {
Component testComponent = (Component) it.next();
ServerComponentUpdate childUpdate = (ServerComponentUpdate) componentUpdateMap.get(testComponent);
fullRefreshUpdate.appendRemovedDescendants(childUpdate);
it.remove();
}
}
/**
* Removes all ServerComponentUpdates from the manager,
* resetting its state to zero. This method is invoked by the
* container once it has retrieved and processed all available updates.
*/
void purge() {
applicationUpdateMap.clear();
componentUpdateMap.clear();
commands = null;
fullRefreshUpdate = null;
cachedComponentUpdates = null;
}
}
