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SharedCollection modifications...

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Level 3

The SharedCollection as shipped is somewhat lacking in functionality. (It doesn't work with classes that implement IUID as described in the documentation.)

The changes are pretty significant, so I'll just post the entire file. FlashBuilder should have no trouble fixing the indentation.

OverviewOfChanges:

     onItemRecieve() wasn't full functional and had some ugliness. I've added updateItem() to perform the item copying and removed most of the ugliness.

     getItemIndexByID() Added as a convenience, we're using it a couple times anyway.

     getItemID() It had been using a cast to IUID, I've changed that to use an property lookup, and while it might be slower, it should be a bit more reliable. (Before, when things went even slightly awry, and the type didn't get carried through the round-trip, it threw an exception. That no longer happens.)

What's left to do:

     updateItem uses describeType and some e4x to do the updating. This is probably expensive, so eventually, we might like to cache the results.

There are a few unit tests that I've written for this along with a mock server for testing (like the LocalServer, but as a class that can be instantiated in a unit test.) I can't attach a file to this post, so I'm not sure how to deliver the tests and their support code. If anyone would like it, let me know and we'll find a place to put it.

If anyone has any feedback, please let me know.

cheers,

sandy

-------------------------------------------------- BEGIN --------------------------------------------------

package com.adobe.rtc.sharedModel

{

import com.adobe.rtc.events.CollectionNodeEvent;

import com.adobe.rtc.messaging.MessageItem;

import com.adobe.rtc.messaging.NodeConfiguration;

import com.adobe.rtc.session.ConnectSession;

import com.adobe.rtc.session.IConnectSession;

import com.adobe.rtc.session.ISessionSubscriber;

import flash.utils.describeType;

import mx.collections.ArrayCollection;

import mx.collections.IList;

import mx.collections.ListCollectionView;

/**

* Dispatched when the SharedCollection goes in and out of sync with the service.

*

*  @eventType com.adobe.rtc.events.CollectionNodeEvent

*/

[Event(name="synchronizationChange", type="com.adobe.rtc.events.CollectionNodeEvent")]

/**

*  Dispatched when the ICollectionView has been updated in some way.

*

*  @eventType mx.events.CollectionEvent.COLLECTION_CHANGE

*/

[Event(name="collectionChange", type="mx.events.CollectionEvent")]

/**

* The type of event emitted when the CollectionNode is about to reconnect to the server.

* This typically happens automatically if the SharedCollection is still subscribed.

* The typical response to this event is to re-initialize any

* shared parts of a model from scratch since they are about to be re-received from the server.

*

*  @eventType mx.events.CollectionEvent.RECONNECT

*/

[Event(name="reconnect", type="mx.events.CollectionEvent")]

/**

* SharedCollection is a simple ListCollectionView which is shared across the AFCS services. Useful for sharing the contents

* of a List or Datagrid (or any other component with a dataProvider), it supports the general addItem, setItemAt, removeItemAt,

* and removeAll methods for updating the collection. Any changes through these APIs are shared with other users subscribed to

* the collection. Note, however, that changing a collection's object properties without calling setItemAt to update them results

* in those properties not being shared.

* <p>

* The collection does not share sort order: Any sorting desired should be performed on each respective client. As such,

* addItemAt isn't supported, although addItem is. The collection makes update decisions on items based on a unique ID.

* Items added to the collection should either implement the IUID interface or provide a field which is guaranteed to be unique

* for this collection. The SharedCollection exposes an <code class="property">idField</code> property to specify which

* field to use as unique ID; in the case the items do not implement IUID.

* <p>

* Use MessageItem.registerBodyClass to preserve class types when sending and receiving from the service.

* Doing so automatically creates instances of the appropriate class and transfers any properties from the

* received item to the typed objects.

* <p>

* The SharedCollection exposes the ability to set NodeConfiguration options for the node upon which the items are sent. In this way

* the collection can have its access and publish rights assigned as well as the other settings allowed by NodeConfiguration.

* Note that this component supports "piggybacking" on existing CollectionNodes through its <code class="property">collectionNode</code> property

* and its subscribe method. Developers can avoid CollectionNode proliferation in their applications by pre-supplying a CollectionNode

* to the <code class="property">collectionNode</code> property and a <code class="property">nodeName</code> (in the subscribe method)

* for the SharedCollection to use. If none is supplied, the SharedCollection will create its own collectionNode named for the

* <code class="property">uniqueID</code> supplied in subscribe()for sending and receiving messages.

*

* @see com.adobe.rtc.messaging.NodeConfiguration

* @see com.adobe.rtc.sharedModel.CollectionNode

* @see mx.core.IUID

*

*/

public class SharedCollection extends ListCollectionView implements ISessionSubscriber

{

/**

* @private

*/

protected var _sharedID:String = "_SharedCollection" ;

/**

* @private

*/

protected var _connectSession:IConnectSession = ConnectSession.primarySession;

/**

* The SharedCollection constructor

* @param p_list The IList this SharedCollection is meant to wrap.

*

*/

public function SharedCollection(p_list:IList=null)

{

if (!p_list) {

p_list = new ArrayCollection();

}

super(p_list);

}

/**

* Specifies an existing collectionNode to use in case a developer wishes to supply their own, and avoid having the

* sharedCollection create a new one.

*/

public var collectionNode:CollectionNode;

/**

* @private

*/

protected static const ITEM_NODE:String = "itemNode";

/**

* @private

*/

protected var _nodeConfig:NodeConfiguration;

/**

* @private

*/

protected var _nodeName:String = ITEM_NODE;

/**

* @private

*/

protected var _myUserID:String;

/**

* If each item doesn't implement IUID, specifies a field within the item to use as a unique ID.

*/

public var idField:String;

/**

* Specifies the class to use in deserializing any items which arrive from the service.

*/

public var itemClass:Class;

[Bindable("synchronizationChange")]

/**

* Returns whether or not the sharedCollection has retrieved any information previously stored on the service, and

* is currently connected to the service.

*/

public function get isSynchronized():Boolean

{

if (collectionNode) {

return collectionNode.isSynchronized;

} else {

return false;

}

}

/**

* Sets the node configuration.

* @param p_nodeConfig The node configuration..

*/

public function setNodeConfiguration(p_nodeConfig:NodeConfiguration):void

{

_nodeConfig = p_nodeConfig ;

if ( isSynchronized ) {

collectionNode.setNodeConfiguration(_nodeName,_nodeConfig);

}

}

/**

* @private

*/

public function getNodeConfiguration():NodeConfiguration

{

return _nodeConfig.clone() ;

}

/**

* Sets the Node name for the node being create

* @param p_nodeConfig The node configuration.

*/

public function set nodeName(p_nodeName:String):void

{

_nodeName = p_nodeName ;

}

/**

* @private

*/

public function get nodeName():String

{

return _nodeName ;

}

/**

* Disposes all listeners to the network and framework classes.

* Recommended for proper garbage collection of the component.

*/

public function close():void

{

collectionNode.removeEventListener(CollectionNodeEvent.SYNCHRONIZATION_CHANGE, onSyncChange);

collectionNode.removeEventListener(CollectionNodeEvent.ITEM_RECEIVE, onItemReceive);

collectionNode.removeEventListener(CollectionNodeEvent.ITEM_RETRACT, onItemRetract);

collectionNode.removeEventListener(CollectionNodeEvent.RECONNECT, onReconnect);

collectionNode.unsubscribe();

collectionNode = null;

}

/**

* Tells the component to begin synchronizing with the service. 

* For "headless" components such as this one, this method must be called explicitly.

*/

public function subscribe():void

{

if ( _nodeConfig == null ) {

_nodeConfig = new NodeConfiguration();

}

_nodeConfig.itemStorageScheme = NodeConfiguration.STORAGE_SCHEME_MANUAL;

if (collectionNode==null) {

collectionNode = new CollectionNode();

collectionNode.sharedID = sharedID ;

collectionNode.connectSession = _connectSession ;

collectionNode.subscribe();

} else {

}

collectionNode.addEventListener(CollectionNodeEvent.SYNCHRONIZATION_CHANGE, onSyncChange);

collectionNode.addEventListener(CollectionNodeEvent.ITEM_RECEIVE, onItemReceive);

collectionNode.addEventListener(CollectionNodeEvent.ITEM_RETRACT, onItemRetract);

collectionNode.addEventListener(CollectionNodeEvent.RECONNECT, onReconnect);

}

/**

* Defines the logical location of the component on the service. Typically this assigns the <code class="property">sharedID</code> of the collectionNode

* used by the component. <code class="property">sharedIDs</code> should be unique within a room if they're expressing 2 unique locations. Note that

* this can only be assigned once before <code>subscribe()</code> is called. For components with an <code class="property">id</code> property,

* <code class="property">sharedID</code> defaults to that value.

*/

public function set sharedID(p_id:String):void

{

_sharedID = p_id;

}

/**

* @private

*/

public function get sharedID():String

{

return _sharedID;

}

/**

* The IConnectSession with which this component is associated. Note that this may only be set once before <code>subscribe</code>

* is called; re-sessioning of components is not supported. Defaults to the first IConnectSession created in the application.

*/

public function get connectSession():IConnectSession

{

return _connectSession;

}

public function set connectSession(p_session:IConnectSession):void

{

_connectSession = p_session;

}

/**

* Replaces the item at the specified index.

* @param The new item to set.

* @param The index of the item to replace. Note that this index is local-only; on remote collections, it's the unique ID

* of the item which is used to locate and replace the item.

* @return The item previously at this location.

*/

override public function setItemAt(p_item:Object, p_index:int):Object

{

var oldItem:Object = getItemAt(p_index);

var msg:MessageItem = new MessageItem(_nodeName, p_item, getItemID(oldItem));

collectionNode.publishItem(msg, true);

return oldItem;

}

/**

* Adds the specified item to the end of the list.

* @param p_item The item to add.

*/

override public function addItem(p_item:Object):void

{

var msg:MessageItem = new MessageItem(_nodeName, p_item, getItemID(p_item));

collectionNode.publishItem(msg);

}

/**

* Removes the item at the specified index.

* @param p_index The index of the item to remove. Note that this index is local-only; on remote collections, it's the

* unique ID of the item which is used to locate and remove the item.

* @return The item preivously at this location.

*

*/

override public function removeItemAt(p_index:int):Object

{

var oldItem:Object = getItemAt(p_index);

collectionNode.retractItem(_nodeName, getItemID(oldItem));

return oldItem;

}

/**

* Removes all items in the collection.

*/

override public function removeAll():void

{

var len:int = length;

for (var i:int=len-1; i>=0; i--) {

removeItemAt(i);

}

}

/**

* @private

*/

protected function onSyncChange(p_evt:CollectionNodeEvent):void

{

if ( collectionNode.isSynchronized ) {

_myUserID = _connectSession.userManager.myUserID;

if (!collectionNode.isNodeDefined(_nodeName) && collectionNode.canUserConfigure(_myUserID, _nodeName)) {

// this collectionNode has never been built, and I can add it...

collectionNode.createNode(_nodeName, _nodeConfig);

}

}

dispatchEvent(p_evt);

}

/**

* @private

* Copy properties from the newItem to the old item.

*  

* @param The item to write the values to.

* @param The item to read the values from.

*

*/

protected function updateItem(oldItem:Object, newItem:Object) : void {

var oldValue:Object;

var newValue:Object;

var key:String;

// Copy all the dynamic properties

for ( key in newItem ) {

oldValue = oldItem[key];

newValue = newItem[key];

if( oldValue != newValue ) {

oldItem[key] = newValue;

itemUpdated(oldItem, key, oldValue, newValue);

}

}

var typeXML:XML = describeType( oldItem );

// Copy all the class properties

for( key in typeXML.variable ) {

var name:String = typeXML.variable[key].@name

oldValue = oldItem[name];

newValue = newItem[name];

if( oldValue != newValue ) {

oldItem[name] = newValue;

itemUpdated(oldItem, name, oldValue, newValue);

}

}

// Copy all the class properties that have read/write accessors

for( key in typeXML.accessor ) {

var isReadWrite:Boolean = typeXML.accessor[key].@access == "readwrite";

var name:String = typeXML.accessor[key].@name;

oldValue = oldItem[name];

newValue = newItem[name];

if( isReadWrite && oldValue != newValue ) {

oldItem[name] = newValue

itemUpdated(oldItem, name, oldValue, newValue);

}

}

}

/**

* @private

*/

protected function onReconnect(p_evt:CollectionNodeEvent):void

{

super.removeAll() ;

dispatchEvent(p_evt);

}

/**

* Pass in the unique id of the item, and get back the index of the item.

* If the item doesn't exist, -1 is

*

* @param The unique id of the item who's index you'd like to retrieve.

*

* @return

* The index of the item.

* -1 if the item doesn't exist in the collection.

*/

public function getItemIndexByID( itemID:String ) : int {

var len:int = length;

for( var i:int=0; i<len; i++) {

var item:Object = getItemAt(i);

if( itemID == getItemID( item ) ) {

return i;

}

}

return -1;

}

/**

* @private

*/

protected function onItemReceive(p_evt:CollectionNodeEvent):void

{

if (p_evt.nodeName!=_nodeName) {

return;

}

var newItem:Object = p_evt.item.body;

var itemID:String = (idField) ? newItem[idField] : newItem['uid'];

var oldItem:Object;

var itemIndex:int = getItemIndexByID(itemID);

if( -1 != itemIndex ) {

oldItem = getItemAt( itemIndex ) ;

updateItem( oldItem, newItem );

super.setItemAt( oldItem, itemIndex );

}else{

if( itemClass ) {

var newItemTyped:Object = new itemClass();

updateItem( newItemTyped, newItem );

super.addItem( newItemTyped );

}else{

super.addItem( newItem );

}

}

}

/**

* @private

*/

protected function onItemRetract(p_evt:CollectionNodeEvent):void

{

if (p_evt.nodeName!=_nodeName) {

return;

}

var newItem:Object = p_evt.item.body;

var itemID:String = (idField) ? newItem[idField] : newItem['uid'];

var oldItem:Object;

var itemIndex:int = getItemIndexByID(itemID);

if( -1 != itemIndex ) {

oldItem = getItemAt( itemIndex );

super.removeItemAt( itemIndex );

}

}

/**

* @private

*

* This exploits the fact that AS3 is a "firmly" typed language.

* It's strongly typed, except for when it's not.

*

* So, rather than casting p_item to IUID,

* we can do things like p_item['uid'] when uid is an accessor in a class instance.

*

*/

protected function getItemID(p_item:Object):String

{

var itemID:String = p_item.hasOwnProperty('uid') ? p_item['uid'] : p_item[idField] as String;

if (itemID==null) {

throw new Error("Each item in a sharedCollection requires a unique ID. Please have your items either implement mx.core.IUID, or " +

"specify 'sharedCollection.idField' so that the collection knows which field of your item is unique.");

} else {

return itemID;

}

}

}

}

--------------------------------------------------- END ----------------------------------------------------

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