Writing ASP Chat using JavaScript and XML (Part 3)

// SharedXML class.
function SharedXML() {
	this.addNode = SharedXML_addNode;
	this.findNode = SharedXML_findNode;
	this.findNodeByName = SharedXML_findNodeByName;
	this.removeNode = SharedXML_removeNode;
	this.getXMLDocument = SharedXML_getXMLDocument;
	this.setAttribte = SharedXML_setAttribte;
	this.getItems = SharedXML_getItems;
	this.applicationIdentifier = "USERS";
	this.xmlSection = "USER";
}

/**
 *  Add new xml node in shared xml. Assign new id to this node.
 *  @return Newly created xml node.
 */
function SharedXML_addNode() {
	var xmlDoc = this.getXMLDocument();
	var root = xmlDoc.firstChild;
	var element = xmlDoc.createElement(this.xmlSection);
	root.appendChild(element);
	var now = new Date();
	var id = now.valueOf();
	this.setAttribte(element, "ID", id);
	return element;
}

/**
 *  Create or rename name-value pair of attribute.
 *  @param name the attribute name.
 *  @param value attribute value.
 */
function SharedXML_setAttribte(xmlNode, name, value) {
	var attributeNode = xmlNode.attributes.getNamedItem(name);
	if(attributeNode != null) {
		attributeNode.nodeValue = value;
	}
	else {
		var xmlDoc = xmlNode.ownerDocument;
		attributeNode = xmlDoc.createAttribute(name);
		attributeNode.nodeValue = value;
		xmlNode.attributes.setNamedItem(attributeNode);
	}
}

/**
 *  Find node by id.
 *  @param id unique id to search.
 *  @return XML node if found or undefined value;
 */
function SharedXML_findNode(id) {
	var xmlDoc = this.getXMLDocument();
	xmlDoc.setProperty("SelectionLanguage", "XPath");
	var root = xmlDoc.firstChild;
	var queryString = "*[@ID=" + id + "]";
	return root.selectSingleNode(queryString);
}

/**
 *  Find node by name.
 *  @param name unique name to search.
 *  @return XML node if found or undefined value;
 */
function SharedXML_findNodeByName(name) {
	var xmlDoc = this.getXMLDocument();
	xmlDoc.setProperty("SelectionLanguage", "XPath");
	var root = xmlDoc.firstChild;
	var queryString = "*[@NAME=\"" + name + "\"]";
	return root.selectSingleNode(queryString);
}

/**
 *  Removes specified node.
 *  @param xmlNode node to delete.
 */
function SharedXML_removeNode(xmlNode) {
	var xmlDoc = this.getXMLDocument();
	var root = xmlDoc.firstChild;
	root.removeChild(xmlNode);
}

/**
 *  Provides access and first time creation of shared XML Document.
 *  @return Shared FreeThreadedDOMDocument object.
 */
function SharedXML_getXMLDocument() {
	if(typeof(Application) != "undefined") {
		var xmlDoc = Application(this.applicationIdentifier);
		if(typeof(xmlDoc) == "undefined") {
			xmlDoc = Server.CreateObject("MSXML.FreeThreadedDOMDocument");
			var rootElement=xmlDoc.createElement("ROOT");
			xmlDoc.appendChild(rootElement);
			Application(this.applicationIdentifier) = xmlDoc;
		}
		return xmlDoc;
	}
	else {
		// Testing purposes only.
		var xmlDoc = app;
		if(typeof(xmlDoc) == "undefined") {
			xmlDoc = WScript.CreateObject("MSXML.FreeThreadedDOMDocument");
			var rootElement=xmlDoc.createElement("ROOT");
			xmlDoc.appendChild(rootElement);
			app = xmlDoc;
		}
		return xmlDoc;
	}
}
var app;

/**
 *  Queries list of data items.
 *  @return XMLNodesList of managed items.
 */
function SharedXML_getItems() {
	var xmlDoc = this.getXMLDocument();
	var itemsList = xmlDoc.getElementsByTagName(this.xmlSection);
	return itemsList;
}

// SharedXML class.