Given the summer recess, it has been a while since my last post but it's time to pull the proverbial socks up and get back to work. During this semester, the blog will be focusing mostly on the eXtensible Markup Language - XML for short - and there's a lot to cover, so let's get right to it:
First Things First
So what is XML? Before answering that question one must understand where XML comes from and more importantly its purpose. To do that we need to take a look at the early days of computing, back in the 1960's, where the idea of storing documents in computers in such a way as to make them "understandible" to software, was still fresh in the minds of researchers.
GML
Charles Goldfarb, Edward Mosher and Raymond Lorie, three researchers working for IBM came up with GML, a set of macros that implemented mark-up tags to describe the logical structure of a document. Interestingly, GML is known today as "Generalized Markup Language" but originally the acronym stood for the researcher's surnames!
GML
Charles Goldfarb, Edward Mosher and Raymond Lorie, three researchers working for IBM came up with GML, a set of macros that implemented mark-up tags to describe the logical structure of a document. Interestingly, GML is known today as "Generalized Markup Language" but originally the acronym stood for the researcher's surnames!
SGML
GML was eventually extended by Goldfarb in the mid 80s into the Standard Generalized Markup Language (SGML). SGML was designed to make it possible for large entities (such as government) to share machine-readable electronic documents. The main idea was to embed a set of tags within a document which a software package could use to derive information about that document. For this to work, the set of tags had to be standardised, made publicly available and most importantly be platform independent. SGML is a very large and complex markup language, suitable for storing equally large and complex documents but rather cumbersome for use with smaller, simpler documents. The beauty of SGML however is that it can be used to derive smaller, simpler mark-up languages better suited for smaller documents. Such languages include HTML (Hyper-Text Markup Language) and of course XML.
XML
Going back to the original question: "What is XML?", XML is an extensible markup language used to encode documents in such a way as to make the knowledge structure of a document known to a software package. It separates the actual content of a document from it's structure and presentation. Being a subset of SGML it is much simpler to use and is ideally suited to store, and more importantly transport, electronic documents. It's most common use today is to transmit data between applications, irrespective of the platform. The beauty of XML is that you define your own tags which means that any document structure can be described in XML.
XML became a W3C Recommendation on February 10, 1998 (w3schools.com) and the first web browser to support XML was Microsoft's Internet Explorer 4.0.
Next time, I will be comparing XML to HTML. In the mean time, have a look at this post from my blog for more on XML.
XML
Going back to the original question: "What is XML?", XML is an extensible markup language used to encode documents in such a way as to make the knowledge structure of a document known to a software package. It separates the actual content of a document from it's structure and presentation. Being a subset of SGML it is much simpler to use and is ideally suited to store, and more importantly transport, electronic documents. It's most common use today is to transmit data between applications, irrespective of the platform. The beauty of XML is that you define your own tags which means that any document structure can be described in XML.
XML became a W3C Recommendation on February 10, 1998 (w3schools.com) and the first web browser to support XML was Microsoft's Internet Explorer 4.0.
Next time, I will be comparing XML to HTML. In the mean time, have a look at this post from my blog for more on XML.
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