HTML and Web Programming

HTML and Web Programming Wen-Nung Tsai http://w3c.org/ ( http://www.w3.org )

Agenda • Review: HTML. DHTML • Web pages (網頁) is simply an HTML file. • Web Application • Dynamic Web Programming • CGI – Common Gateway Interface • XUL ? XML-based User-interface Language • Programming in FaceBook • References

Terminologies • WWW – World Wide Web • HTML – Hyper Text Markup Language • HTTP – Hyper Text Transfer Protocol • URL – Uniform Resource Locator • Hyperlinks and Links • Web Browser • Web Server, Application Server • http://w3c.org

The Internet versus the Web THE INTERNET TheInternet is a collection of interconnected networks. THE WEB The Web is a system that provides access to documents formatted in hypertext that uses languages such as HTML or XML. versus Slide 5 of 30

Web Application • Web Applications are developed to use a Web browser as the interface to the application to allow users to input, retrieve and process data of certain types. They create dynamic Web pages to dynamically respond to user inputs.

Web Application Architecture DBMS Browser

Google API … RSS OAI-PMH … … SOAP XMLRPC REST … HTTP … TCP/IP Network Hardware Layered Web Interoperability …

What is HTTP? • Protocol for transfer of data between Web servers and Web clients (browsers). • Popular Web servers: • Apache HTTPD • JBoss • Tomcat • Popular Web clients: • Mozilla , Firefox, Netscape, MSIE • Chrome, HotJava, Hotdog, Opera • wget • Defined formally by IETF as RFC2616.

URLs, URNs and URIs • Every resource accessible through HTTP is identified by a Uniform Resource Location (URL), which is a location-specific identifier. • For example, • http://www.cs.uct.ac.za:80/ • ftp://ftp.cs.uct.ac.za/ • A Uniform Resource Identifier (URI) is a standard format (<scheme>:<identifier>) generic identifier. • For example, • mailto:hussein@cs.uct.ac.za • oai:www.ndltd.org:123456-789 • A Uniform Resource Name (URN) is one example of a location-independent URI. • For example, • urn:isbn:123-456-789 • Note: Every URL and URN is also a URI!

What is HTML ? • HTML – HyperText Markup Language • HTML file is Essentially a text file, containing small markup tags.( 排版語言) • Markup tags tell the Web Browser how to read and display the page. I.e., how to lay out the information (text, images, etc) in the browser window. • an opening tag <html> and a closing tag </html> with the content that the tag is applied to, in between them.

HTML Page (Web Page) 外觀 <html><head><title>名稱</title></head><body>內容 <tag attribute=val … > … </tag> </body></html> • Titile讓首頁製作者以簡短的文字表達此一首頁之內容。Title的內容會出現在瀏覽器的頂端。若將某個首頁加入書籤，則Title內容變成該書籤名稱。

HTML Elements • Headings, Font Sizes, Color • Comments • Backgrounds • Links and hyperlinks • E-mail • Pictures • Lists • Tables, Frames, …

進階語法－CSS介紹(1/2) • 超連結去底線 • 【語法】 • 1.在<head>…</head>加入下列語法 • <style> • a{text-decoration:none} • </style> • 2.在<body>…</body>加入下列語法 • <a style="text-decoration: none" href="網址">連結名稱</a>

進階語法－CSS介紹 (2/2) <html> <head> <title>CSS應用</title> <style> a{text-decoration:none} </style> </head> <body> <a style="text-decoration: none" href="http://www.sinica.edu.tw">中央研究院</a> </body> </html>

Tools to build a Web Page • You can just use NOTE PAD • Write some bunch of code in a HTML file • Or you can use WYSIWYG (pronounced "wiz-ee-wig", means “What You See Is What You Get) editors. • Netscape Composer • Microsoft Front Page • Dreamweaver MX • Hundreds of other Editors available on the Internet – the Cyber spaces 

Dynamic Web Programming • HTML + CGI + … • Client side: Java script, VB script • Server side: • CGI : Using PERL, TCL, Python, Ruby, … • ASP, PHP, JSP • DBMS • Oracle, MSSQL, MySQL, … • J2EE, ASP.Net • PHP + MySQL [ + Tomcat ] (注意 JavaScript 不是 Java)

Dynamic web pages • Client-side • Examples: java applets, javascript/VBScript, Macromedia Flash • Server-side • Common Gateway Interface (CGI) • Servlets • ASP, PHP, JSP

What is DHTML? (1/2) • DHTML is the combination of several built-in browser features in fourth generation browsers that enable a web page to be more dynamic. • DHTML is NOT a scripting language (like JavaScript), but a browser feature- or enhancement- that makes the browser dynamic • It uses a host of different technologies - JavaScript, VBScript, the Document Object Model (DOM), layers, cascading stylesheets - to create HTML that can change even after a page has been loaded into a browser

What is DHTML? (2/2) • It is considered to be made up of • HTML • Cascading Style Sheets (CSS) • Scripting Language • All three of these components are linked via Document Object Model (DOM) • DOM is the interfacethat allows scripting languages to access the content, style, and structure of the web documents and change them dynamically

Tools of DHTML • HTMLandXML • Partitions and Organizes the content • CSS, XSL - CSS1, CSSP, CSS2 • Defines the Presentation of the content • Scripting - JavaScript, JScript, VBScript • Adds interactivity to the page • DOM- Document Object Model • Defines what and how elements are exposed for script access

CGI – Common Gateway Interface • CGI = 共通閘道介面 • Standard interface through which users interact with applications on Web servers • Provides way for clients to interact with applications on Web server • CGI script • Can be written in many different languages, including Perl • Practical Extraction and Report Language (Perl) • One of the most widely used language for Web programming • Python -- http://en.wikipedia.org/wiki/Python_(programming_language) • Ruby -- http://en.wikipedia.org/wiki/Ruby_(programming_language)

Active Server Pages (ASP) • ASP code enclosed in: <% VBScript code %> • When a browser calls an ASP document, the ASP Server reads the .asp document and • Substitutes appropriate files for the (server-side) include statements • Runs the ASP code (Visual Basic Script – see the Tutorial and Language Reference, …) • Returns the resulting HTML code to the browser JSP -- Java Server Page (sun micro)

PHP: Hypertext Preprocessor. • PHP stands for PHP: Hypertext Preprocessor. • HTML embedding scripting language • PHP code enclosed in <?php PHP code ?> or <? PHP code ?> • When a browser calls a PHP document, the Server reads the PHP document and • Runs the PHP code • Returns the resulting HTML code to the browser JSP -- Java Server Page (sun micro)

What is XUL ? • XML-based User interface Language (“zool”) • An XML grammar to add/modify UI widgets of the browser • Makes UI building easier and faster • Uses W3C standards: HTML, XML, CSS, DOM • XPToolkit is the finite set of interface-specific elements created in XUL • XPFE (cross Platform Front End) is the front end created from XPToolkit • XUL provides flexibility and ease of use • Cross-platform UI easily • Power enough to build application UI • Ready-made widgets

XUL Widget & Syntax • Widget: • Window, box, menu, button, tabbox, checkbox, … • Syntax & Rules: • XUL is case sensitive: all events and attribute must be written in lower case • All strings must be double quoted • All attributes must have a value • XUL file extension: .xul

Inside XUL package • Main components • Content: • XUL files describes XML description of UI • Appearance: • CSS, images, and others control presentation • Behavior: • JavaScript defines event handling within widgets • Locale: • All localizable strings in external DTD

XUL and JavaScript • XUL interface is a collection of disconnected widgets until programmed • Using JavaScript and/or C++ • JavaScript included in XUL or a separate file <html:script> function InitWindow( ) { var checkbox = document.getElementByID("remember"); if (checkbox) checkbox.checked = true; } </html:script> <html:script language="javascript" src="myscript.js"/>

Adding Event Handlers • JavaScript • DOM Event Listener

Chrome URI’s • XUL files are loaded via chrome URI’s chrome://<package name>/<part>/<file.xul> • The chrome URI has three parts: Package name : Given by user Type of data : Content or Skin or Locale Content : xul and js files Skin : images and css files Locale : DTD and .properties files File name : Path of the file to load

XUL Overlays • Overlays attach other UI widgets to XUL documents at run time. • XUL fragments are inserted at specific merge points in the master document. • For example:<statusbar id="status-bar"> <statusbarpanel id="my-panel" label="Hello, World"/> </statusbar> • “status-bar” is the merge point and “my-panel” is the new XUL fragment

XUL file <?xml version="1.0"?> <overlay id="sample" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> <script type="application/x-javascript" src="chrome://sample/content/test.js"/> <?xml-stylesheet href="chrome://sample/skin/test.css" type="text/css"?> <statusbar id="status-bar"> <statusbarpanel id="my-panel" label="Hello World"/> </statusbar>

Programming in Facebook Hussein Suleman uct cs honours 2007

What is Facebook?

How Facebook Apps work • Every profile page is made up of many independent portlets or profile boxes. • Each portlet is generated statically by a possibly external application and stored by Facebook. • It could be an iframe, but in most cases is not. • Portlets are not actually changed in the profile page – they are changed elsewhere! • Facebook has mechanisms to link in applications, and APIs for applications to communicate with Facebook.

request for profile profile request for canvas request for canvas content Facebook API use update profile box, etc. canvas canvas user facebook.com Facebook Communication application (UCT)

What can the API do ? • Get a list of friend ids or friends who are running the same app • Get and set notifications of events • Set content of profile box • Get specific information on a user • Add to the Newsfeed for a user • etc. See: http://developers.facebook.com/documentation.php?v=1.0&doc=

FBML • Language used by Facebook to specify any fragment of Web pages. • Mostly just like HTML! • Forms get additional fields added to pass Facebook parameters silently. • Images are redirected to local copies. • Links must be absolute (parameters do not work as expected in all toolkits). • Lots of additional Facebook-specific items • <fb:name uid=…> for a user’s name • <fb:profile-pic …> for a user’s profile picture

FQL • Facebook Query Language allows access to user database with language that is similar to SQL. • Example: • SELECT first_name FROM user WHERE uid=$params->{user} • To get the first name of a user based on the user-id

Creating an Application • What you need: • Web Server • API toolkit or roll-your-own • Add the Developer application to your profile. • Switch to the Developer application. • Apply for a key.

What does a typical application do? • Check CGI parameters. • Authenticate using Facebook API. • Draw configuration Web page on canvas. • Allow user to update options … • Write FBML to profile box. • Save per-user state in database or in filesystem.

Example: Profile Box

Example: Application Canvas

The Code – index.pl • #!/usr/bin/perl • # • # sample adapted from Facebook Perl API example • # hussein suleman • # 31 july 2007 • use strict; • use CGI; • use WWW::Facebook::API; • use Data::Dumper; • use LWP::UserAgent; • use XML::DOM; • # create FB object with keys included • my $facebook = WWW::Facebook::API->new( • api_key => "8a3b63fde6e900f853c51903e6689e5b", • secret => "f1818d69d7140fa0192b623b55e7da59", • app_path => "hussein_testb", • parse => 1, • ); • # remember to add proxy for UCT! • $facebook->ua->proxy ('http', 'http://cache.uct.ac.za:8080/'); • sub main { • # handler CGI parameters • my $q = new CGI; • print $q->header; • redirect("Must be called in facebook canvas") • unless $facebook->canvas->in_fb_canvas($q); • my $params = $facebook->canvas->validate_sig($q); • if ( $params->{user} ) { • # Canvas takes care of setting up a session for us, no need to call the

# auth methods. • $facebook->session_key( $params->{session_key} ); • } • else { • # User hasn't added app (could reject/display info/whatever) • # (Or handle later when a user is needed). • } • my ( $action, $param ) = ( $q->path_info =~ m!^/(\w+)/?(.*)! ); • # trigger action depending on parameters passed to app • if ($action eq '') • { handle_index($param, $params); } • else • { print_error ("cannot understand request"); } • } • # canvas drawing routine • sub handle_index { • my ( $param, $params ) = @_; • print "<fb:header/>"; • print "<h1>Watch My Students</h1>"; • print "<fb:profile-pic uid=\"$params->{user}\"/> "; • # list data from disk file with links to delete entries • print "<h2><fb:name uid=\"$params->{user}\" useyou=\"false\"/>\'s Current Wat • ched Entries</h2>"; • my $fbml = "<b>Watch My Students</b><hr/><p>Sneak peek at what the 1016 stude • nts are chatting about in the class forum ...</p><ul>"; • print "<ul>";

open (my $ofile, "data.txt"); • my $po = 0; • while (my $aline = <$ofile>) • { • $po++; • chomp $aline; • print "<li><a href=\"http://banzai.cs.uct.ac.za/~hussein/cgi-bin/2007/face • book/perl/delete.pl?position=$po\">Delete</a> $aline</li>"; • $fbml .= "<li>$aline</li>"; • } • close ($ofile); • print "</ul>"; • $fbml .= "</ul>"; • print "<hr/>"; • # list data from RSS feed with links to add entries • print "<h2><fb:name uid=\"$params->{user}\" useyou=\"false\"/>\'s Latest RSS • Entries</h2>"; • print "<ul>"; • my $results = get_RSS(); • $po = 0; • foreach my $aresult (@$results) • { • $po++; • $aresult->[2] =~ s/\<[^\>]+\>//go; • print "<li><a href=\"http://banzai.cs.uct.ac.za/~hussein/cgi-bin/2007/face • book/perl/add.pl?position=$po\">$aresult->[0] (by $aresult->[1])</a><br/>$aresul • t->[2]</li>"; • } • print "</ul>"; • # add application if it has not been added • if ( !$params ) { • print "<a href='", $facebook->get_add_url,

HTML and Web Programming