IBM Version 5 manual XML history, Extensibility, Industry acceptance

required, the development cost would rise. However, if the data could be re-used or built upon, there would be a re-development savings.

Imagine a navigation system used by consumers to move from one place to another. This system would have street maps, yellow pages information, local attractions and other information. If this information has to be displayed on a Web browser, personal device assistant (PDA) or a mobile phone, it would be a major development costs if we had to develop three separate data access systems and three data presentation systems. However, if we develop one data access systems, we also need to create three data presentation files for each system, which transforms XML using the XSLT transformation feature.

Extensibility

HTML has a major problem in that it is not extensible. It has been enhanced upon by the different software vendors. These enhancements have not been co-ordinated, and therefore, have become non-standard. It was never designed to access data from databases. To overcome this deficiency, Microsoft built Active Server Pages (ASP) and Sun produced Java Server Pages (JSP).

As the name implies, XML was designed from the beginning to allow extensions.

Industry acceptance

XML has been accepted by widely by the information and computing Industry. It is based on common concepts. As time goes on, a large number of XML tools will emerge from both existing software vendors and XML startup companies. It is readable by every operating systems, because it is in ASCII text. This implies that it can be seen by any text editor or word processor.

The tree-based structure of XML is much more powerful than fixed-length data formats. Because objects are tree structures as well, XML is ideally suited to working with object-oriented programming.

1.5 XML history

The history of XML is really the history of another system: Standard Generalized Markup Language or SGML. XML is actually just a subset of SGML, and SGML has been around for many years. In fact, SGML dates back to the late 60s and the work of an IBM employee Charles Goldfarb. Goldfarb was developing a system to share documents, and together with two of his colleagues, Edward Mosher and Raymond Lorie, he put together a markup language called Generalized Markup Language (GML). (Of course, GML really stands for Goldfarb, Mosher, and Lorie, who invented it.)

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