World Wide Web Programming 2 – Main Programming Languages
The basics - HTML HTML: HyperText Markup Language Universal Resource Identifier
• Every page has a URI, sometimes known as URL. Ex…
Joe Cool http://somesite.com/html/top.html#section_2
Relative URIs •
What is the use of URIs on HTML?
Link to another document or resource Link to an external style sheet or script Include an image, object, or applet in a page Create an image map Submit a form Create a frame document Cite an external reference Refer to metadata conventions describing a document
What is HTML? Publishing language for WWW The actual version is HTML4 It is a markup language Interpreted directly by the browsers It’s a “client-side” language
The Creator - SGML SGML is a system for defining markup languages HTML is an example of a markup language Uses a DTD (Document Type Definition) to define the syntax of markup constructs
Other SGML derived languages
XML (eXtensible Markup Language) • Huge role in data exchange • Defines types of files
XSL (eXtensible Stylesheet Language) • Language for expressing stylesheets • Thanks to XSLT (XSL Transformations) it can transform an XML document into something well formatted
The good old Java Java has gained a big importance on the Web through technologies such as J2EE or J2ME Most common use is the creation of web applets Slow, terribly slow Complicated to use, terribly complicated to use (at least for the Web)
Something different: JavaScript Compact, object-based scripting language for developing client and server Internet applications Most applications run on client side, so the code is visible Different than Java!
Java vs. JavaScript
JavaScript
• Interpreted (not compiled) by client • Object-based Uses built-in, extensible objects, but no classes or inheritance • Code integrated with HTML • Variable data types not declared • Dynamic binding. Object references checked at runtime • Cannot automatically write to hard disk
Java
• Compiled bytecodes downloaded from server to client • Object-oriented Applets consist of object classes with inheritance • Applets distinct from HTML • Variables data types MUST be declared • Static binding. Object references must exist at compile-time • Cannot automatically write to hard disk
The savior: PHP
Recursive acronym for Hypertext Preprocessor Open Source scripting language Suited for Web development, embedded into HTML Server-side execution Extremely simple to learn (as you’ll all see) Can be used to create server-side applications, command line scripting, client-side GUI applications (with PHP-GTK) Works with all major databases (compatible with a total of 21, including Oracle, MySQL, PostgreSQL, ODBC, Sybase, …)
The rival: ASP.NET ASP Language is another powerful scripting language Built on the Common Language Runtime used for the .NET platform Used for Web Services Very efficient, loved by many companies, but not open source… It’s a kind of “PHP for high class”
The “myth”: CGI
Common Gateway Interface Not an actual language Standard for interfacing external applications with information servers Executed in real-time, so the output is dynamic A CGI program can be written on C/C++, Fortran, PERL, TCL, any UNIX shell, Visual Basic or AppleScript
Another big option: Perl Open Source Popular due to its facility with text manipulation and rapid development cycle Amazon.com partly built on Perl Can be embedded on any Web server Can interface with external C/C++ libraries through XS or SWIG
The future? C#.NET Language created entirely for the .NET platform Strongly uses XML Object Oriented Very similar to Visual Basic
Client-side vs. Server-side
Client-side applications: • Usually run by the browsers thanks to plug-ins • Code is totally visible
Server-side applications: • Executed on the server so only the output can be read by the client • Impossible to read the code
Why PHP & MySQL? PHP is one of the most powerful free languages for Web programming Easy to learn (appropriate for a single semester course) MySQL is also a powerful FREE database that couples perfectly with PHP Also because I decided so…
