<com:TContent ID="body" > <h1 id="401">My First PRADO Application</h1> <p> In this section, we guide you through creating your first PRADO application, the famous "Hello World" application. </p> <p> "Hello World" perhaps is the simplest <i>interactive</i> PRADO application that you can create. It displays to end-users a page with a submit button whose caption is <tt>Click Me</tt>. After the user clicks on the button, its caption is changed to <tt>Hello World</tt>. </p> <p> There are many approaches that can achieve the above goal. One can submit the page to the server, examine the POST variable, and generate a new page with the button caption updated. Or one can simply use JavaScript to update the button caption upon its <tt>onclick</tt> client event. </p> <p> PRADO promotes component-based and event-driven Web programming. The button is represented by a <tt>TButton</tt> object. It encapsulates the button caption as the <tt>Text</tt> property and associates the user button click action with a server-side <tt>OnClick</tt> event. To respond to the user clicking on the button, one simply needs to attach a function to the button's <tt>OnClick</tt> event. Within the function, the button's <tt>Text</tt> property is modified as "Hello World". The following diagram shows the above sequence, </p> <img src="<%~sequence.gif%>" /> <p> Our PRADO application consists of three files, <tt>index.php</tt>, <tt>Home.page</tt> and <tt>Home.php</tt>, which are organized as follows, </p> <img src="<%~directory.gif%>" /> <p> where each directory is explained as follows. Note, the above directory structure can be customized. For example, one can move the <tt>protected</tt> directory out of Web directories. You will know how to do this after you go through this tutorial. </p> <ul> <li><tt>assets</tt> - directory storing published private files. See <a href="?page=Advanced.Assets">assets</a> section for more details. This directory must be writable by the Web server process.</li> <li><tt>protected</tt> - application base path storing application data and private script files. This directory should be configured as inaccessible to end-users.</li> <li><tt>runtime</tt> - application runtime storage path storing application runtime information, such as application state, cached data, etc. This directory must be writable by the Web server process.</li> <li><tt>pages</tt> - base path storing all PRADO pages.</li> </ul> <p> The three files that we need are explained as follows. </p> <ul> <li><tt>index.php</tt> - entry script of the PRADO application. This file is required by all PRADO applications and is the only script file that is directly accessible by end-users. Content in <tt>index.php</tt> mainly consists of the following three lines, <com:TTextHighlighter CssClass="source"> require_once('path/to/prado.php'); // include the prado script $application=new TApplication; // create a PRADO application instance $application->run(); // run the application </com:TTextHighlighter> </li> <li><tt>Home.page</tt> - template for the default page returned when users do not explicitly specify the page requested. A template specifies the presentational layout of components. In this example, we use two components, <tt>TForm</tt> and <tt>TButton</tt>, which correspond to the <form> and <input> HTML tags, respectively. The template contains the following content, <com:TTextHighlighter Language="prado" CssClass="source"> <html> <body> <com:TForm> <com:TButton Text="Click me" OnClick="buttonClicked" /> </com:TForm> </body> </html> </com:TTextHighlighter> </li> <li><tt>Home.php</tt> - page class for the <tt>Home</tt> page. It mainly contains the method responding to the <tt>OnClick</tt> event of the button. <com:TTextHighlighter CssClass="source"> class Home extends TPage { public function buttonClicked($sender,$param) { // $sender refers to the button component $sender->Text="Hello World!"; } } </com:TTextHighlighter> </li> </ul> <p> The application is now ready and can be accessed via: <tt>http://Web-server-address/helloworld/index.php</tt>, assuming <tt>helloworld</tt> is directly under the Web <tt>DocumentRoot</tt>. Try to change <tt>TButton</tt> in <tt>Home.page</tt> to <tt>TLinkButton</tt> and see what happens. </p> <p> Complete source code of this demo can be found in the PRADO release. You can also try the <a href="http://www.pradosoft.com/demos/helloworld/">online demo</a>. </p> </com:TContent>