Why use XML
XML is the Extensible Markup Language.It improves the functionality of the Web by letting identify information in a more accurate, flexible, and adaptable way.It is extensible because it is not a fixed format like HTML (which is a single, predefined markup language).Instead, XML is actually a metalanguage—a language for describing other languages—which lets design own markup languages for limitless different types of documents. XML can do this because it's written in SGML, the international standard metalanguage for text document markup (ISO 8879). Here are a few reasons for using XML
1.XML can be used to describe and identify information accurately and unambiguously, in a way that computers can be programmed to ‘understand’ information (well, at least manipulate as if they could understand it).
2.XML allows documents which are all the same type to be created and handled consistently and without structural errors, because it provides a standardised way of describing, controlling, or allowing/disallowing particular types of document structure. Note that this has absolutely nothing whatever to do with formatting, appearance, or the actual text or data content of the documents, only the structure of them?.
3.XML provides a robust and durable format for information storage and transmission. Robust because it is based on a proven standard, and can thus be tested and verified; durable (persistent) because it uses plain-text file formats which will outlast proprietary binary ones.
4.XML provides a common syntax for messaging systems for the exchange of information between applications. Previously, each messaging system had its own format and all were different, which made inter-system messaging unnecessarily messy, complex, and expensive. If everyone uses the same syntax it makes writing these systems much faster and more reliable.
5.XML is free. Not just free of charge (free as in beer) but free of legal encumbrances (free as in speech). It doesn't belong to anyone, so it can't be hijacked or pirated. And you don't have to pay a fee to use it (you can of course choose to use commercial software to deal with it, for lots of good reasons, but you don't pay for XML itself).
6.XML information can be manipulated programmatically (under machine control), so XML documents can be pieced together from disparate sources, or taken apart and re-used in different ways. They can be converted into any other format with no loss of information.
7.XML lets you separate form (appearance) from content. Your XML file contains your document information (text, data) and identifies its structure: your formatting and other processing needs are identified separately in a style sheet or processing system. The two are combined at output time to apply the required formatting to the text or data identified by its structure (location, position, rank, order, or whatever).
Saturday, April 3, 2010
XSL
Why use XSL?
The process of transforming and formatting information into a rendered result is called styling. Advantages to separating content from style
• Contrary to when style information is hard-coded into the content, separation of style from content allows for the same data to be presented in different ways. This enables:
• reuse of fragments of data: the same content should look different in different contexts
• multiple output formats: different media (paper, online), different sizes (manuals, reports), different classes of output devices (workstations, hand-held devices)
• styles tailored to the reader's preference (e.g., accessibility): print size, color, simplified layout for audio readers
• standardized styles: corporate stylesheets can be applied to the content at any time
• freedom from style issues for content authors: technical writers needn't be concerned with layout issues because the correct style can be applied later The full XSL language logically consists of three component languages which are described in three W3C (World Wide Web Consortium) Recommendations:
• XPath: XML Path Language--a language for referencing specific parts of an XML document
• XSLT: XSL Transformations--a language for describing how to transform one XML document (represented as a tree) into another.
• XSL: Extensible Stylesheet Language--XSLT plus a description of a set of Formatting Objects and Formatting Properties. An XSL processor takes a stylesheet consisting of a set of XSL commands and transforms it, using an input XML document.
The process of transforming and formatting information into a rendered result is called styling. Advantages to separating content from style
• Contrary to when style information is hard-coded into the content, separation of style from content allows for the same data to be presented in different ways. This enables:
• reuse of fragments of data: the same content should look different in different contexts
• multiple output formats: different media (paper, online), different sizes (manuals, reports), different classes of output devices (workstations, hand-held devices)
• styles tailored to the reader's preference (e.g., accessibility): print size, color, simplified layout for audio readers
• standardized styles: corporate stylesheets can be applied to the content at any time
• freedom from style issues for content authors: technical writers needn't be concerned with layout issues because the correct style can be applied later The full XSL language logically consists of three component languages which are described in three W3C (World Wide Web Consortium) Recommendations:
• XPath: XML Path Language--a language for referencing specific parts of an XML document
• XSLT: XSL Transformations--a language for describing how to transform one XML document (represented as a tree) into another.
• XSL: Extensible Stylesheet Language--XSLT plus a description of a set of Formatting Objects and Formatting Properties. An XSL processor takes a stylesheet consisting of a set of XSL commands and transforms it, using an input XML document.
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