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Writing ASP Chat using JavaScript and XML (Part 4)

, 21 Jan 2004
The last part of the ASP chat series. This article explains how to provide a chat with multiple rooms.
// UserManager class.
/**
 *  Users managing functions.
 */
function UserManager() {
	this.loginUser = UserManager_loginUser;
	this.getSessionID = UserManager_getSessionID;
	this.findSession = UserManager_findSession;
	this.getUserNick = UserManager_getUserNick;
	this.formatUsers = UserManager_formatUsers;
	this.removeSession = UserManager_removeSession;
	this.checkExpiration = UserManager_checkExpiration;
	this.isValidSession = UserManager_isValidSession;
	this.getUsersCount = UserManager_getUsersCount;
	this.save = UserManager_save;
	this.switchRoom = UserManager_switchRoom;
	this.copySessionToRoom = UserManager_copySessionToRoom;
	this.getRoomSessions = UserManager_getRoomSessions;
	this.identifier = "USERS";
}

/**
 *  Checks for user existence by specified name.
 *  @param roomID room of this user.
 *  @param strUserName user nick name.
 *  @return Active session ID or -1 if not exists.
 */
function UserManager_getSessionID(roomID, strUserName) {
	var session = this.findSession(roomID, strUserName);
	if(typeof(session) != "undefined") {
		return session.getSessionID();
	}
	else {
		return -1;
	}
}

/**
 *  Create new session in hidden room.
 *  @param strUserName user name to add.
 *  @param clientIP IP address.
 *  @return New session id.
 */
function UserManager_loginUser(strUserName, clientIP) {
	var session = this.findSession(0, strUserName);
	if(typeof(session) != "undefined") {
		return session.getSessionID();	
	}
	// Access hidden room.
	var users = this.getRoomSessions(0);	
	var xmlNode = users.addNode();
	var newSession = new Session(xmlNode, true);
	newSession.setUserNick(strUserName);
	newSession.setClientIP(clientIP);
	return newSession.getSessionID();
}

/**
 *  Retraives node of specified room and associates specified class with it.
 * If the room not found, created new one with this id.
 *  @return new instance of SingleLevelXML class or null if not found.
 */
function UserManager_getRoomSessions(roomID) {
	var allRooms = new SharedXML(this.identifier);
	var roomNode = allRooms.findNode(roomID);
	if(roomNode == null) {
		// Create room if not exists.
		roomNode = allRooms.insertNode(roomID);
	}
	if(roomNode != null) {
		return new SingleLevelXML(roomNode);
	}
	return null;
}

/**
 *  Remove session with specified session ID.
 *  @param sessionID session ID to remove.
 */
function UserManager_removeSession(roomID, sessionID) {
	var users = this.getRoomSessions(roomID);
	var xmlNode = users.findNode(sessionID);
	if(xmlNode != null) {
		users.removeNode(xmlNode);
	}
}

/**
 *  Searching for user nick by session ID.
 *  @param sessionID session id.
 *  @return Valid user name or undefined value if user not exists.
 */
function UserManager_getUserNick(roomID, sessionID) {
	var users = this.getRoomSessions(roomID);
	var xmlNode = users.findNode(sessionID);
	if(xmlNode != null) {
		var session = new Session(xmlNode);
		return session.getUserNick();
	}
}

/**
 *  Searching for an existing sesion by user nick in specified room. Also it cheks 
 * for user expiration.
 *  @param roomID room of this user.
 *  @param strNick user nick.
 *  @return Found session object or undefined, if not exists.
 */
function UserManager_findSession(roomID, strNick) {
	var users = this.getRoomSessions(roomID);
	var xmlNode = users.findNodeByName(strNick);
	if(xmlNode != null)
	{
		var session = new Session(xmlNode, true);
		if(session.doesExpired()) {
			// Remove expired node.
			users.removeNode(xmlNode);
		}
		else {
			return session;
		}
	}
}

/**
 *  Check expiration of session. If expired session removed.
 *  @param xmlNode XML node to check.
 *  @return true if expiration occurs owervise false.
 */
function UserManager_checkExpiration(xmlNode) {
	var s = new Session(xmlNode, false);
	if(s.doesExpired()) {
		// Remove expired node.
		var users = xmlNode.parentNode;
		if(users != null) {
			users.removeChild(xmlNode);
			return true;
		}
	}
	return false;
}

/**
 *  User session validation.
 *  @param sessionID session id.
 *  @return true if session exists, overvise false.
 */
function UserManager_isValidSession(roomID, sessionID) {
	var users = this.getRoomSessions(roomID);
	var xmlNode = users.findNode(sessionID);
	return (xmlNode != null);
}

/**
 *  Formats users list for specified session.
 */
function UserManager_formatUsers(roomID, sessionID) {
	if(!this.isValidSession(roomID, sessionID)) {
		return "";
	}
	var users = this.getRoomSessions(roomID);
	var strUsers = "";
	var items = users.getItems();
	var i = 0;
	while(i < items.length) {
		var x = items.item(i);
		if(!this.checkExpiration(x)) {
			var s = new Session(x, false);
			var id = s.getSessionID();
			if(sessionID == id) {
				var continueSession = new Session(x, true);
				continueSession.markLastAccessTime();
			}
			strUsers += "<img src=\"img/user.gif\" border=0>"
			strUsers += s.getUserNick();
			strUsers += "<BR>\n";
		}
		i++;
	}
	return strUsers;
}

/**
 *  Retraiving quantity of currently logged users in specified room.
 */
function UserManager_getUsersCount(roomID) {
	var users = this.getRoomSessions(roomID);
	var items = users.getItems();
	return items.length;
}

/**
 *  Save shared data. For testing purposes.
 */
function UserManager_save(fileName) {
	var users = new SharedXML(this.identifier);
	users.save(fileName);
}

/**
 *  Move user from one room to another.
 */
function UserManager_switchRoom(roomIDOld, roomIDNew, sessionID) {
	var previousRoom = this.getRoomSessions(roomIDOld);
	var oldXmlNode = previousRoom.findNode(sessionID);
	if(oldXmlNode != null) {
		var targetRoom = this.getRoomSessions(roomIDNew);
		var xmlNode = targetRoom.findNode(sessionID);
		if(xmlNode == null) {
			// Session not exist. Processed session moving.
			xmlNode = oldXmlNode.cloneNode(false);
			targetRoom.insertXmlNode(xmlNode);
			var newSession = new Session(xmlNode, true);
			newSession.markLastAccessTime();
		}
		// Removing from previous room.
		previousRoom.removeNode(oldXmlNode);
	}
}

/**
 *  Clone session for another room.
 */
function UserManager_copySessionToRoom(roomIDOld, roomIDNew, sessionID) {
	var previousRoom = this.getRoomSessions(roomIDOld);
	var oldXmlNode = previousRoom.findNode(sessionID);
	if(oldXmlNode != null) {
		var targetRoom = this.getRoomSessions(roomIDNew);
		var xmlNode = targetRoom.findNode(sessionID);
		if(xmlNode == null) {
			// Session not exist. Processed session moving.
			xmlNode = oldXmlNode.cloneNode(false);
			targetRoom.insertXmlNode(xmlNode);
			var newSession = new Session(xmlNode, true);
			newSession.markLastAccessTime();
		}
	}
}
// UserManager class.

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About the Author

Alexander Fedorenko
Web Developer
Ukraine Ukraine
Alexander Fedorenko is a professional C++ developer since 1996. He completed many custom and shareware projects. One of the successful projects is DevPlanner - tool for personal planning and time management.

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