What is XSL?
Remember the good old days, when the internet consisted of nothing more than a few simple websites formatted in basic HTML? Web design was so easy.
You could just slap some graphics and text into a file, insert some HTML tags into the document to tell the web browser how the text should appear and what the structure of the page should be, and presto, the job was finished.
As time went on, web design became more arduous. Businesses, especially ecommerce businesses that depended upon their internet storefronts to make a living, began to present web designers with near impossible projects that were too difficult to complete with basic HTML. The data being used and the designs that were being implemented for websites required more versatile programming specifications.
What resulted was the evolution of new specifications and languages for creating web sites. Languages and sub-languages such as XML, XHTML, style sheets, and a host of other more refined and yet more flexible specifications were spliced together to take web design to a new level.
One of the most important languages that came to be in recent years is called XSL. What is XSL, you ask? Well, to totally understand what XSL is and why it is so important, you must first understand XML.
XML is a markup language just like HTML. XML was created to deal with the fact that HTML was limited in that all of its tags were predefined and it displayed data a certain way. XML has no predefined tags, and does not tell a computer how data should appear, it merely defines the data. So, using XML, a web designer can define all sorts of data and more effectively transmit this data to web browsers installed on different platforms that run on a variety of electronic gadgets such as cell phones and other handheld devices that now come equipped with internet access. In a nutshell, XML was created to deal with the fact that so many different electronic products now come equipped with access to the internet and email. These new devices run on platforms that do not always display data properly if it is coded using HTML. XML fixed this situation by simply defining data and not forcing the web browser to display it a certain way, because an XML file is merely a simple text file.
So, again you ask, what is XSL and why is it important? XSL stands for Extensible Stylesheet Language. You have probably heard of Cascading Style Sheets (CSS). CSS is a style sheet language that evolved to make it easier for web designers to create a style for an HTML web page. Because XML is now so important, and because XML tags, as explained in the previous paragraph, do not tell the web browser how data should appear, a stylesheet language that was XML-based became a necessity.
XSL consists of 3 components. The first and most important component is XSLT. XSLT transforms an XML document into another XML document that can actually be understood and displayed by a computer. It accomplishes this by transforming most of the document into XHTML, which is a more versatile, cross-platform, XML-based version of HTML.
The second part of XSL is XPath. XPath is used as the navigator for XSL. XSL uses XPath to find parts of the source document that should match a certain predefined template. When XPath finds what it is looking for, then XSLT takes over and performs a transformation, turning the source document into what is called the result document.
The final part of XSL is known as XSL-FO. This component is for the final formatting. Once XPath has searched through the source document and used XSLT to transform the source document into the result document, the document then needs to be formatted so that the web browser will be able to present the document with the proper layout and structure. Simply put, XSL-FO is the part of XSL that produces the final output.
There are all sorts of helpful online tutorials for programmers and web designers to begin to learn how to use and implement XSL, but it would probably be best take a course in XSL at a local institute, college, or wherever you can find one. If web design is your career, learning it is not an option, it is a necessity, as most web browsers are now capable of understanding XSL. Since the advent of wireless internet access, everything from cell phones, to palm tops, to computer screens in automobiles can be used to connect to the internet. These different devices run on different platforms and have different web browsers that cannot properly display many elements of the HTML programming language. As a result, it is critical for all web designers to be able to create web pages using cross-platform specifications with the adaptability provided by XSL.
Jim Pretin is the owner of http://www.forms4free.com, a service that helps programmers make email forms.