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diff --git a/demos/quickstart/protected/pages/Tutorial/AjaxChat.page b/demos/quickstart/protected/pages/Tutorial/AjaxChat.page new file mode 100644 index 00000000..3a17b5d4 --- /dev/null +++ b/demos/quickstart/protected/pages/Tutorial/AjaxChat.page @@ -0,0 +1,753 @@ +<com:TContent ID="body"> + <h1>Building an AJAX Chat Application</h1> + <p>This tutorial introduces the Prado web application framework's + <a href="?page=Database.ActiveRecord">ActiveRecord</a> + and <a href="?page=ActiveControls.Home">Active Controls</a> to build a Chat + web application . It is assumed that you + are familiar with PHP and you have access to a web server that is able to serve PHP5 scripts. + This basic chat application will utilizing the following ideas/components in Prado. + <ul> + <li>Building a custom User Manager class.</li> + <li>Authenticating and adding a new user to the database.</li> + <li>Using ActiveRecord to interact with the database.</li> + <li>Using Active Controls and callbacks to implement the user interface.</li> + <li>Separating application logic and application flow.</li> + </ul> + </p> + + <p>In this tutorial you will build an AJAX Chat web application that allows + multiple users to communicate through their web browser. + The application consists of two pages: a login page + that asks the user to enter their nickname and the main application chat + page. + You can try the application <a href="../chat/index.php">locally</a> or at + <a href="http://www.pradosoft.com/demos/chat/">Pradosoft.com</a>. + The main application chat page is shown bellow. + <img src=<%~ chat1.png %> class="figure" /> + </p> + + <h1>Download, Install and Create a New Application</h1> + <p>The download and installation steps are similar to those in + the <a href="?page=Tutorial.CurrencyConverter#download">Currency converter tutorial</a>. + To create the application, we run from the command line the following. + See the <a href="?page=GettingStarted.CommandLine">Command Line Tool</a> + for more details. +<com:TTextHighlighter Language="text" CssClass="source"> +php prado/framework/prado-cli.php -c chat +</com:TTextHighlighter> + </p> + + <p>The above command creates the necessary directory structure and minimal + files (including "index.php" and "Home.page") to run a Prado web application. + Now you can point your browser's url to the web server to serve up + the <tt>index.php</tt> script in the <tt>chat</tt> directory. + You should see the message "Welcome to Prado!" + </p> + + <h1>Authentication and Authorization</h1> + <p>The first task for this application is to ensure that each user + of the chat application is assigned with a unique (choosen by the user) + username. To achieve this, we can secure the main chat application + page to deny access to anonymouse users. First, let us create the <tt>Login</tt> + page with the following code. We save the <tt>Login.php</tt> and <tt>Login.page</tt> + in the <tt>chat/protected/pages/</tt> directory (there should be a <tt>Home.page</tt> + file there create by the command line tool). + </p> +<com:TTextHighlighter Language="php" CssClass="source"> +<?php +class Login extends TPage +{ +} +?> +</com:TTextHighlighter> +<com:TTextHighlighter Language="prado" CssClass="source"> +<!doctype html public "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> +<head> + <title>Prado Chat Demo Login</title> +</head> +<body> +<com:TForm> + <h1 class="login">Prado Chat Demo Login</h1> + <fieldset class="login"> + <legend>Please enter your name:</legend> + <div class="username"> + <com:TLabel ForControl="username" Text="Username:" /> + <com:TTextBox ID="username" MaxLength="20" /> + <com:TRequiredFieldValidator + ControlToValidate="username" + Display="Dynamic" + ErrorMessage="Please provide a username." /> + </div> + <div class="login-button"> + <com:TButton Text="Login" /> + </div> +</com:TForm> +</body> +</html> +</com:TTextHighlighter> + <p>The login page contains + a <com:DocLink ClassPath="System.Web.UI.WebControls.TForm" Text="TForm" />, + a <com:DocLink ClassPath="System.Web.UI.WebControls.TTextBox" Text="TTextBox" />, + a <com:DocLink ClassPath="System.Web.UI.WebControls.TRequiredFieldValidator" Text="TRequiredFieldValidator" /> + and a <com:DocLink ClassPath="System.Web.UI.WebControls.TButton" Text="TButton" />. The resulting + page looks like the following (after applying some a style sheet). + <img src=<%~ chat2.png %> class="figure" /> + If you click on the <tt>Login</tt> button without entering any + text in the username textbox, an error message is displayed. This is + due to the <com:DocLink ClassPath="System.Web.UI.WebControls.TRequiredFieldValidator" Text="TRequiredFieldValidator" /> + requiring the user to enter some text in the textbox before proceeding. + </p> +<h2>Securing the <tt>Home</tt> page</h2> +<p>Now we wish that if the user is trying to access the main application +page, <tt>Home.page</tt>, before they have logged in, the user is presented with +the <tt>Login.page</tt> first. We add a <tt>chat/protected/application.xml</tt> configuration +file to import some classes that we shall use later. +<com:TTextHighlighter Language="xml" CssClass="source"> +<?xml version="1.0" encoding="utf-8"?> +<application id="Chat" Mode="Debug"> + <paths> + <using namespace="System.Data.*" /> + <using namespace="System.Data.ActiveRecord.*" /> + <using namespace="System.Security.*" /> + <using namespace="System.Web.UI.ActiveControls.*" /> + </paths> +</application> +</com:TTextHighlighter> +Next, we add a <tt>chat/protected/pages/config.xml</tt> configuration file to +secure the <tt>pages</tt> directory. +<com:TTextHighlighter Language="xml" CssClass="source"> +<?xml version="1.0" encoding="utf-8"?> +<configuration> + <modules> + <module id="users" class="TUserManager" /> + <module id="auth" class="TAuthManager" UserManager="users" LoginPage="Login" /> + </modules> + <authorization> + <allow pages="Login" users="?" /> + <allow roles="normal" /> + <deny users="*" /> + </authorization> +</configuration> +</com:TTextHighlighter> +We setup the authentication using the default classes as explained in the +<a href="?page=Advanced.Auth">authentication/authorization quickstart</a>. +In the authorization definition, we allow anonymouse users to access the +<tt>Login</tt> page (anonymouse users is specified by the <tt>?</tt> question mark). +We allow any users with role equal to "normal" (to be defined later) +to access all the pages, that is, the <tt>Login</tt> and <tt>Home</tt> pages. +Lastly, we deny all users without any roles to access any page. The authorization +rules are executed on first match basis. +</p> + +<p>If you now try to access the <tt>Home</tt> page by pointing your browser +to the <tt>index.php</tt> you will be redirected to the <tt>Login</tt> page. +</p> + +<h1>Active Record for <tt>chat_users</tt> table</h1> +<p>The <com:DocLink ClassPath="System.Secutity.TUserManager" Text="TUserManager" /> +class only provides a read-only list of users. We need to be able to add or +login new users dynamically. So we need to create our own user manager class. +First, we shall setup a database with a <tt>chat_users</tt> table and create an ActiveRecord +that can work with the <tt>chat_users</tt> table with ease. For the demo, we +use <tt>sqlite</tt> as our database for ease of distributing the demo. The demo +can be extended to use other databases such as MySQL or Postgres SQL easily. +We define the <tt>chat_users</tt> table as follows. +<com:TTextHighlighter Language="text" CssClass="source"> +CREATE TABLE chat_users +( + username VARCHAR(20) NOT NULL PRIMARY KEY, + last_activity INTEGER NOT NULL DEFAULT "0" +); +</com:TTextHighlighter> +Next we define the corresponding <tt>ChatUserRecord</tt> class and save it as +<tt>chat/protected/App_Code/ChatUserRecord.php</tt> (you need to create the +<tt>App_Code</tt> directory as well). We also save the sqlite database file +as <tt>App_Code/chat.db</tt>. +<com:TTextHighlighter Language="php" CssClass="source"> +class ChatUserRecord extends TActiveRecord +{ + public $username; + public $last_activity; + + public static $_tablename='chat_users'; + + public static function finder() + { + return parent::getRecordFinder('ChatUserRecord'); + } +} +</com:TTextHighlighter> +Before using the <tt>ChatUserRecord</tt> class we to configure a default +database connection for ActiveRecord to function. In the <tt>chat/protected/application.xml</tt> +we import classes from the <tt>App_Code</tt> directory and add an +<a href="?page=Database.ActiveRecord">ActiveRecord configuration module</a>. +<com:TTextHighlighter Language="xml" CssClass="source"> +<?xml version="1.0" encoding="utf-8"?> +<application id="Chat" Mode="Debug"> + <paths> + <using namespace="Application.App_Code.*" /> + <using namespace="System.Data.*" /> + <using namespace="System.Data.ActiveRecord.*" /> + <using namespace="System.Security.*" /> + <using namespace="System.Web.UI.ActiveControls.*" /> + </paths> + <modules> + <module class="TActiveRecordConfig" EnableCache="true" + Database.ConnectionString="sqlite:protected/App_Code/chat.db" /> + </modules> +</application> +</com:TTextHighlighter> +</p> + +<h2>Custom User Manager class</h2> +<p>To implement a custom user manager module class we just need +to extends the <tt>TModule</tt> class and implement the <tt>IUserManager</tt> +interface. The <tt>getGuestName()</tt>, <tt>getUser()</tt> and <tt>validateUser</tt> +methods are required by the <tt>IUserManager</tt> interface. +We save the custom user manager class as <tt>App_Code/ChatUserManager.php</tt>. +</p> +<com:TTextHighlighter Language="php" CssClass="source"> +class ChatUserManager extends TModule implements IUserManager +{ + public function getGuestName() + { + return 'Guest'; + } + + public function getUser($username=null) + { + $user=new TUser($this); + $user->setIsGuest(true); + if($username !== null && $this->usernameExists($username)) + { + $user->setIsGuest(false); + $user->setName($username); + $user->setRoles(array('normal')); + } + return $user; + } + + public function addNewUser($username) + { + $user = new ChatUserRecord(); + $user->username = $username; + $user->save(); + } + + public function usernameExists($username) + { + $finder = ChatUserRecord::finder(); + $record = $finder->findByUsername($username); + return $record instanceof ChatUserRecord; + } + + public function validateUser($username,$password) + { + return $this->usernameExists($username); + } +} +</com:TTextHighlighter> +<p> +The <tt>getGuestName()</tt> +method simply returns the name for a guest user and is not used in our application. +The <tt>getUser()</tt> method returns a <tt>TUser</tt> object if the username +exists in the database, the <tt>TUser</tt> object is set with role of "normal" +that corresponds to the <tt><authorization></tt> rules defined in our +<tt>config.xml</tt> file. </p> + +<p>The <tt>addNewUser()</tt> and <tt>usernameExists()</tt> +method uses the ActiveRecord corresponding to the <tt>chat_users</tt> table to +add a new user and to check if a username already exists, respectively. +</p> + +<p>The next thing to do is change the <tt>config.xml</tt> configuration to use +our new custom user manager class. We simply change the <tt><module></tt> +configuration with <tt>id="users"</tt>.</p> +<com:TTextHighlighter Language="xml" CssClass="source"> +<module id="users" class="ChatUserManager" /> +</com:TTextHighlighter> + +<h1>Authentication</h1> +<p>To perform authentication, we just want the user to enter a unique +username. We add a +<com:DocLink ClassPath="System.Web.UI.WebControls.TCustomValidator" Text="TCustomValidator" /> +for validate the uniqueness of the username and add a <tt>OnClick</tt> event handler +for the login button.</p> +<com:TTextHighlighter Language="prado" CssClass="source"> +<com:TCustomValidator + ControlToValidate="username" + Display="Dynamic" + OnServerValidate="checkUsername" + ErrorMessage="The username is already taken." /> + +... + +<com:TButton Text="Login" OnClick="createNewUser" /> +</com:TTextHighlighter> +In the <tt>Login.php</tt> file, we add the following 2 methods. +<com:TTextHighlighter Language="php" CssClass="source"> +function checkUsername($sender, $param) +{ + $manager = $this->Application->Modules['users']; + if($manager->usernameExists($this->username->Text)) + $param->IsValid = false; +} + +function createNewUser($sender, $param) +{ + if($this->Page->IsValid) + { + $manager = $this->Application->Modules['users']; + $manager->addNewUser($this->username->Text); + + //do manual login + $user = $manager->getUser($this->username->Text); + $auth = $this->Application->Modules['auth']; + $auth->updateSessionUser($user); + $this->Application->User = $user; + + $url = $this->Service->constructUrl($this->Service->DefaultPage); + $this->Response->redirect($url); + } +} +</com:TTextHighlighter> +The <tt>checkUserName()</tt> method uses the <tt>ChatUserManager</tt> class +(recall that in the <tt>config.xml</tt> configuration we set the +ID of the custom user manager class as "users") to validate the username +is not taken. +</p> +<p> +In the <tt>createNewUser</tt> method, when the validation passes (that is, +when the user name is not taken) we add a new user. Afterward we perform +a manual login process: +<ul> + <li>First we obtain a <tt>TUser</tt> instance from +our custom user manager class using the <tt>$manager->getUser(...)</tt> method.</li> + <li>Using the <tt>TAuthManager</tt> we set/update the user object in the + current session data.</li> + <li>Then we set/update the <tt>Application</tt>'s user instance with our + new user object.</li> +</ul> +Finally, we redirect the client to the default <tt>Home</tt> page. +</p> + +<h2>Default Values for ActiveRecord</h2> +<p>If you try to perform a login now, you will receive an error message like +"<i>Property '<tt>ChatUserRecord::$last_activity</tt>' must not be null as defined +by column 'last_activity' in table 'chat_users'.</i>". This means that the <tt>$last_activity</tt> +property value was null when we tried to insert a new record. We need to either +define a default value in the corresponding column in the table and allow null values or set the default +value in the <tt>ChatUserRecord</tt> class. We shall demonstrate the later by +altering the <tt>ChatUserRecord</tt> with the addition of a set getter/setter +methods for the <tt>last_activity</tt> property. + +<com:TTextHighlighter Language="php" CssClass="source"> +private $_last_activity; + +public function getLast_Activity() +{ + if($this->_last_activity === null) + $this->_last_activity = time(); + return $this->_last_activity; +} + +public function setLast_Activity($value) +{ + $this->_last_activity = $value; +} +</com:TTextHighlighter> +Notice that we renamed <tt>$last_activity</tt> to <tt>$_last_activity</tt> (note +the under score after the dollar sign). +</p> + +<h1>Main Chat Application</h1> +<p>Now we are ready to build the main chat application. We use a simple +layout that consist of one panel holding the chat messages, one panel +to hold the users list, a textare for the user to enter the text message +and a button to send the message. +<com:TTextHighlighter Language="prado" CssClass="source"> +<!doctype html public "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> +<head> + <title>Prado Chat Demo</title> +<style> +.messages +{ + width: 500px; + height: 300px; + float: left; + border: 1px solid ButtonFace; + overflow: auto; +} +.user-list +{ + margin-left: 2px; + float: left; + width: 180px; + height: 300px; + border: 1px solid ButtonFace; + overflow: auto; + font-size: 0.85em; +} +.message-input +{ + float: left; +} + +.message-input textarea +{ + margin-top: 3px; + padding: 0.4em 0.2em; + width: 493px; + font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; + font-size: 0.85em; + height: 40px; +} +.send-button +{ + margin: 0.5em; +} +</style> +</head> +<body> +<com:TForm> +<h1>Prado Chat Demo</h1> +<div id="messages" class="messages"> + <com:TPlaceHolder ID="messageList" /> +</div> +<div id="users" class="user-list"> + <com:TPlaceHolder ID="userList" /> +</div> +<div class="message-input"> + <com:TActiveTextBox ID="userinput" + Columns="40" Rows="2" TextMode="MultiLine" /> + <com:TActiveButton ID="sendButton" CssClass="send-button" + Text="Send" /> +</div> +</com:TForm> +<com:TJavascriptLogger /> +</body> +</html> +</com:TTextHighlighter> +We have add two Active Control components: a +<com:DocLink ClassPath="System.Web.UI.ActiveControls.TActiveTextBox" Text="TActiveTextBox" /> +and a +<com:DocLink ClassPath="System.Web.UI.ActiveControls.TActiveButton" Text="TActiveButton" />. +We also added a +<com:DocLink ClassPath="System.Web.UI.WebControls.TJavascriptLogger" Text="TJavascriptLogger" /> +that will be very useful for understanding how the Active Controls work. +</p> + +<h2>Exploring the Active Controls</h2> +<p>Lets have some fun before we proceed with setuping the chat buffering. We want +to see how we can update the current page when we receive a message. First, we add +an <tt>OnClick</tt> event handler for the <tt>Send</tt> button. + +<com:TTextHighlighter Language="prado" CssClass="source"> +<com:TActiveButton ID="sendButton" CssClass="send-button" + Text="Send" OnClick="processMessage"/> +</com:TTextHighlighter > +And the corresponding event handler method in the <tt>Home.php</tt> class (we +need to create this new file too). +<com:TTextHighlighter Language="php" CssClass="source"> +class Home extends TPage +{ + function processMessage($sender, $param) + { + echo $this->userinput->Text; + } +} +</com:TTextHighlighter> +If you now type something in the main application textbox and click the send button +you should see what ever you have typed echoed in the <tt>TJavascriptLogger</tt> console. +</p> + +<p>To append or add some content to the message list panel, we need to use +some methods in the +<com:DocLink ClassPath="System.Web.UI.ActiveControls.TCallbackClientScript" Text="TCallbackClientScript" /> +class which is available through the <tt>CallbackClient</tt> property of the +current <tt>TPage</tt> object. For example, we do can do +<com:TTextHighlighter Language="php" CssClass="source"> +function processMessage($sender, $param) +{ + $this->CallbackClient->appendContent("messages", $this->userinput->Text); +} +</com:TTextHighlighter> +This is one way to update some part of the existing page during a callback (AJAX style events) +and will be the primary way we will use to implement the chat application. +</p> + +<h1>Active Record for <tt>chat_buffer</tt> table</h1> +<p>To send a message to all the connected users we need to buffer or store +the message for each user. We can use the database to buffer the messages. The +<tt>chat_buffer</tt> table is defined as follows. +<com:TTextHighlighter Language="text" CssClass="source"> +CREATE TABLE chat_buffer +( + id INTEGER PRIMARY KEY, + for_user VARCHAR(20) NOT NULL, + from_user VARCHAR(20) NOT NULL, + message TEXT NOT NULL, + created_on INTEGER NOT NULL DEFAULT "0" +); +</com:TTextHighlighter> +The corresponding <tt>ChatBufferRecord</tt> class is saved as +<tt>App_Code/ChatBufferRecord.php</tt>. + +<com:TTextHighlighter Language="php" CssClass="source"> +class ChatBufferRecord extends TActiveRecord +{ + public $id; + public $for_user; + public $from_user; + public $message; + private $_created_on; + + public static $_tablename='chat_buffer'; + + public function getCreated_On() + { + if($this->_created_on === null) + $this->_created_on = time(); + return $this->_created_on; + } + + public function setCreated_On($value) + { + $this->_created_on = $value; + } + + public static function finder() + { + return parent::getRecordFinder('ChatBufferRecord'); + } +} +</com:TTextHighlighter> +</p> + +<h1>Chat Application Logic</h1> +<p>We finally arrive at the guts of the chat application logic. First, we +need to save a received message into the chat buffer for <b>all</b> the +current users. We add this logic in the <tt>ChatBufferRecord</tt> class. + +<com:TTextHighlighter Language="php" CssClass="source"> +public function saveMessage() +{ + foreach(ChatUserRecord::finder()->findAll() as $user) + { + $message = new self; + $message->for_user = $user->username; + $message->from_user = $this->from_user; + $message->message = $this->message; + $message->save(); + if($user->username == $this->from_user) + { + $user->last_activity = time(); //update the last activity; + $user->save(); + } + } +} +</com:TTextHighlighter> +We first find all the current users using the <tt>ChatUserRecord</tt> finder +methods. Then we duplicate the message and save it into the database. In addition, +we update the message sender's last activity timestamp. The above piece of code +demonstrates the simplicty and succintness of using ActiveRecords for simple database designs. +</p> + +<p>The next piece of the logic is to retreive the users messages from the buffer. +We simply load all the messages for a particular username and format that message +appropriately (remember to escape the output to prevent Cross-Site Scripting attacks). +After we load the messages, we delete those loaded messages and any older +messages that may have been left in the buffer. +</p> +<com:TTextHighlighter Language="php" CssClass="source"> +public function getUserMessages($user) +{ + $content = ''; + foreach($this->findAll('for_user = ?', $user) as $message) + $content .= $this->formatMessage($message); + $this->deleteAll('for_user = ? OR created_on < ?', $user, time() - 300); //5 min inactivity + return $content; +} + +protected function formatMessage($message) +{ + $user = htmlspecialchars($message->from_user); + $content = htmlspecialchars($message->message); + return "<div class=\"message\"><strong>{$user}:</strong> <span>{$content}</span></div>"; +} +</com:TTextHighlighter> + +To retrieve a list of current users (formatted), we add this logic to the +<tt>ChatUserRecord</tt> class. We delete any users that may have been inactive +for awhile. +<com:TTextHighlighter Language="php" CssClass="source"> +public function getUserList() +{ + $this->deleteAll('last_activity < ?', time()-300); //5 min inactivity + $content = '<ul>'; + foreach($this->findAll() as $user) + $content .= '<li>'.htmlspecialchars($user->username).'</li>'; + $content .= '</ul>'; + return $content; +} +</com:TTextHighlighter> + +<div class="note"><b class="tip">Note:</b> +For simplicity +we formatted the messages in these Active Record classes. For large applications, +these message formatting tasks should be done using Prado components (e.g. using +a TRepeater in the template or a custom component). +</div> +</p> + +<h1>Putting It Together</h1> +<p>Nows comes to put the application flow together. In the <tt>Home.php</tt> we update +the <tt>Send</tt> buttons <tt>OnClick</tt> event handler to use the application +logic we just implemented. +<com:TTextHighlighter Language="php" CssClass="source"> +function processMessage($sender, $param) +{ + if(strlen($this->userinput->Text) > 0) + { + $record = new ChatBufferRecord(); + $record->message = $this->userinput->Text; + $record->from_user = $this->Application->User->Name; + $record->saveMessage(); + + $this->userinput->Text = ''; + $messages = $record->getUserMessages($this->Application->User->Name); + $this->CallbackClient->appendContent("messages", $messages); + $this->CallbackClient->focus($this->userinput); + } +} +</com:TTextHighlighter> +We simply save the message to the chat buffer and then ask for all the messages +for the current user and update the client side message list using a callback +response (AJAX style). +</p> + +<p>At this point the application is actually already functional, just not very +user friendly. If you open two different browser, you should be able to communicate +between the two users when ever the <tt>Send</tt> button is clicked. +</p> + +<p>The next part is perphaps the more tricker and fiddly than the other tasks. We +need to improve the user experience. First, we want a list of current users +as well. So we add the following method to <tt>Home.php</tt>, we can call +this method when ever some callback event is raised, e.g. when the <tt>Send</tt> +button is clicked. +<com:TTextHighlighter Language="php" CssClass="source"> +protected function refreshUserList() +{ + $lastUpdate = $this->getViewState('userList',''); + $users = ChatUserRecord::finder()->getUserList(); + if($lastUpdate != $users) + { + $this->CallbackClient->update('users', $users); + $this->setViewstate('userList', $users); + } +} +</com:TTextHighlighter> +</p> + +<p>Actually, we want to periodically update the messages and user list as new +users join in and new message may arrive from other users. So we need to refresh +the message list as well.</p> +<com:TTextHighlighter Language="php" CssClass="source"> +function processMessage($sender, $param) +{ + ... + $this->refreshUserList(); + $this->refreshMessageList(); + ... +} + +protected function refreshMessageList() +{ + //refresh the message list + $finder = ChatBufferRecord::finder(); + $content = $finder->getUserMessages($this->Application->User->Name); + if(strlen($content) > 0) + { + $anchor = (string)time(); + $content .= "<a href=\"#\" id=\"{$anchor}\"> </a>"; + $this->CallbackClient->appendContent("messages", $content); + $this->CallbackClient->focus($anchor); + } +} +</com:TTextHighlighter> +The anchor using <tt>time()</tt> as ID for a focus point is so that when the +message list on the client side gets very long, the focus method will +scroll the message list to the latest message (well, it works in most browsers). +</p> + +<p>Next, we need to redirect the user back to the login page if the user has +been inactive for some time, say about 5 mins, we can add this check to any stage +of the page life-cycle. Lets add it to the <tt>onLoad()</tt> stage. +<com:TTextHighlighter Language="php" CssClass="source"> +public function onLoad($param) +{ + $username = $this->Application->User->Name; + if(!$this->Application->Modules['users']->usernameExists($username)) + { + $auth = $this->Application->Modules['auth']; + $auth->logout(); + + //redirect to login page. + $this->Response->Redirect($this->Service->ConstructUrl($auth->LoginPage)); + } +} +</com:TTextHighlighter> +</p> + +<h1>Improving User Experience</h1> +<p>The last few details are to periodically check for new messages and +refresh the user list. We can accomplish this by polling the server using a +<com:DocLink ClassPath="System.Web.UI.ActiveControls.TTimeTriggeredCallback" Text="TTimeTriggeredCallback" /> +control. We add a <tt>TTimeTriggeredCallback</tt> to the <tt>Home.page</tt> +and call the <tt>refresh</tt> handler method to defined in <tt>Home.php</tt>. +We set the polling interval to 2 seconds. +<com:TTextHighlighter Language="prado" CssClass="source"> +<com:TTimeTriggeredCallback OnCallback="refresh" + Interval="2" StartTimerOnLoad="true" /> +</com:TTextHighlighter> +<com:TTextHighlighter Language="php" CssClass="source"> +function refresh($sender, $param) +{ + $this->refreshUserList(); + $this->refreshMessageList(); +} +</com:TTextHighlighter> +</p> + +<p>The final piece requires us to use some javascript. We want that when the +user type some text in the textarea and press the <tt>Enter</tt> key, we want it +to send the message without clicking on the <tt>Send</tt> button. We add to the +<tt>Home.page</tt> some javascript. + +<com:TTextHighlighter Language="javascript" CssClass="source"> +<com:TClientScript> +Event.observe($("<%= $this->userinput->ClientID %>"), "keypress", function(ev) +{ + if(Event.keyCode(ev) == Event.KEY_RETURN) + { + if(Event.element(ev).value.length > 0) + new Prado.Callback("<%= $this->sendButton->UniqueID %>"); + Event.stop(ev); + } +}); +</com:TClientScript> +</com:TTextHighlighter> +Details regarding the javascript can be explored in the +<a href="?page=Advanced.Scripts">Introduction to Javascript</a> section of the quickstart. +</p> + +<p>This completes the tutorial on making a basic chat web application using +the Prado framework. Hope you have enjoyed it. +</p> + +</com:TContent>
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