| Evolution of XML |
| What is XML? |
| The eXtensible Markup Language (XML) is a general-purpose markup language. Its primary purpose is to facilitate the sharing of data across different information systems, particularly via the Internet. |
| It is a simplified subset of the Standard Generalized Markup Language (SGML), and is designed to be relatively human-legible. By adding semantic constraints, application languages can be implemented in XML. These include XHTML, RSS, MathML, GraphML, Scalable Vector Graphics(SVG), MusicXML, and thousands of others. Moreover, XML is sometimes used as the specification language for such application languages. |
| XML is nothing by itself. XML is more of a “common ground” standard. The main benefit of XML is that you can take data from a program like MSSQL(Microsoft SQL), convert it into XML, then share that XMLwith a slough of other programs, platforms, etc. Each of these receiving platforms can then convert the XML into a structure the platform uses normally and presto! you have just communicated between two potentially very different platforms! |
| History of Markup languages…… |
| A markup language combines text and extra information about the text. The extra information, for example about the text’s structure or presentation, is expressed using markup, which is intermingled with the primary text. |
| The best-known markup language in modern use is HTML (HyperText Markup Language), one of the foundations of the World Wide Web. Originally markup was used in the publishing industry in the communication of printed work between authors, editors, and printers. |
| GenCode |
| The idea of “markup languages” was apparently first presented in 1967, by William W. Tunnicliffe at a conference. Tunnicliffe would later lead the development of a standard called GenCode for the publishing industry. |
| Book designer Stanley Fish also published speculation along similar lines in the late 1960s. Brian Reid, in his 1980 dissertation at Carnegie Mellon University, developed the theory and a working implementation of descriptive markup in actual use. |
| However, IBM researcher Charles Goldfarb is more commonly seen today as the “father” of markup languages, because of his work on IBM GML, and then as chair of the International Organization for Standardization committee that developed SGML, the first widely used descriptive markup system. |
| SGML |
| Standard Generalized Markup Language |
| The first language to make a clear and clean distinction between structure and presentation was certainly Scribe, which was developed by Brian Reid and described in his doctoral thesis in 1980. |
| Scribe was revolutionary in a number of ways, not least that it introduced the idea of styles separated from the marked up document, and of a grammar controlling the usage of descriptive elements. Scribe influenced the development of Generalized Markup Language (GML)(later SGML) and is a direct ancestor to HTML and LaTeX. |
| SGML specified a syntax for including the markup in documents, as well as one for separately describing what tags were allowed, and where (the Document Type Definition (DTD) or schema). |
| This allowed authors to create and use any markup they wished, selecting tags that made the most sense to them and were named in their own natural languages. Thus, SGML is properly a meta-language, and many particular markup languages are derived from it. |
| From the late 80s on, most substantial new markup languages have been based on SGML system, including for example TEI and DocBook. SGML was promulgated as an International Standard by International Organization for Standardization, ISO 8879, in 1986. |
| The Rise of XML |
| The flexibility of SGML for lively information display was understood by early digital media publishers in the late 1980s prior to the rise of the Internet By the mid-1990s some practitioners of SGML had gained experience with the then-new WWW, and believed that SGML offered solutions to some of the problems the Web was likely to face as it grew. |
| Dan Connolly added SGML to the list of W3C’s activities when he joined the staff in 1995; work began in mid-1996 when Jon Bosak developed a charter and recruited collaborators. Bosak was well connected in the small community of people who had experience both in SGML and the Web. He received support in his efforts from Microsoft. |
| XML was compiled by a working group of eleven members, supported by an (approximately) 150-member Interest Group. Technical debate took place on the Interest Group mailing list and issues were resolved by consensus or, when that failed, majority vote of the Working Group. |
| The decision record was compiled by Michael Sperberg-McQueen on December 4th 1997. James Clarkserved as Technical Lead of the Working Group, notably contributing the empty-element ” ” syntax and the name “XML”. |
| Other names that had been put forward for consideration included “MAGMA” (Minimal Architecture for Generalized Markup Applications), “SLIM” (Structured Language for Internet Markup) and “MGML” (Minimal Generalized Markup Language). |
| The co-editors of the specification were originally Tim Bray and Michael Sperberg-McQueen. Halfway through the project Bray accepted a consulting engagement with Netscape, provoking vociferous protests from Microsoft. Bray was temporarily asked to resign the editorship. This led to intense dispute in the Working Group, eventually solved by the appointment of Microsoft’s Jean Paoli as a third co-editor. |
| The XML Working Group never met face-to-face; the design was accomplished using a combination of email and weekly teleconferences. The major design decisions were reached in twenty weeks of intense work between July and November of 1996, when the first Working Draft of an XML specification was published. Further design work continued through 1997, and XML 1.0 became a W3CRecommendation on February 10, 1998. |
| XML 1.0 achieved the Working Group’s goals of Internet usability, general-purpose usability, SGMLcompatibility, facilitation of easy development of processing software, minimization of optional features, legibility, formality, conciseness, and ease of authoring. Like its antecedent SGML, XML allows for some redundant syntactic constructs and includes repetition of element identifiers. In these respects, terseness was not considered essential in its structure. |