web technology Write 300- to 600-word response to the following discussion topic
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Question
web technology
Write 300- to 600-word response to the following discussion topics and post your answers to the discussion board topic "XML":
Discuss the development and history of XML.
Describe the basic syntax rules of XML.
Write a 150-word response to one peer in which you respectfully and professionally offer your opinion of his or her post:
Pose a clarifying question (e.g., What did you mean by…, Why did you say…, What criteria did you use…, What was your intention…, What is the connection…, What were your assumptions…?).
Provide an application or practical example (e.g., I have seen an example of this..., The result of this
0-word response to the following discussion topics and post your answers to the discussion board topic "XML":
Discuss the development and history of XML.
Describe the basic syntax rules of XML.
Write a 150-word response to one peer in which you respectfully and professionally offer your opinion of his or her post:
Pose a clarifying question (e.g., What did you mean by…, Why did you say…, What criteria did you use…, What was your intention…, What is the connection…, What were your assumptions…?).
Provide an application or practical example (e.g., I have seen an example of this..., The result of this
could be…).
Explanation / Answer
Evolution/History of XML.
The first formal markup language was created by IBM in 1960.It was knows as GML(Generalized Markup Language).Using GML, a document is marked up with tags that define what the text is, in terms of paragraphs, headers, lists, tables, and so forth.The document can then be automatically formatted for various devices simply by specifying a profile for the device. SGML(Standard Generalized Markup Language) has come from this and it became standard for many future different markup languages.
Standard generalized markup language (SGML) is a text markup language that serves as a superset of widely used markup languages like HTML (hypertext markup language) and XML (extensible markup language). SGML is used for marking up documents and has the advantage of not being dependent on a specific application.SGML (Standard General Markup Language) was complex for Internet. SGML needed DTD that can specify individual industry need. This DTD and various optional features of SGML madeSGML complex for internet. Flexible nature of SGML made its rule fuzzy and browser vendors started to make it suitable for their own need made it inflexible for Internet.
Scientists at CERN need to exchange research papers and refer many papers on regular basis. Working this way and managing all the papers was not easy those days. You can understand this. Great Tim Berners-Lee and few others realize that he can create a simple document structure that will allow to link documents. They also thought of document structure that would help browser how document would be viewed. This is called HTML. HTML has retained all the simple features of SGML.
HTML was good for static text, it solved presentational, and layout aspects. It was not good as metadata and exchanging data in structured manner. It was not adequate for data-oriented nature of information exchange.
XML was formed out of SGML for solving all the above problems. Earlier experiences with all mentioned technologies available at that time made inventing XML easier. Jon Bosak, Tim Bray, James Clark, and a few others came up with the idea of an eXtensible Markup Language (XML). Bray (who worked at Sun Microsystems) was an invited expert at the World Wide Web Consortium (W3C) and co-editor of the XML and XML namespace specifications, but it was Bosak who decided that HTML wasn’t a suitable technology for use in greater information exchanges.XML was created so that richly structured documents could be used over the web. The only viable alternatives, HTML and SGML, are not practical for this purpose.
XML Syntax Rules
The syntax rules of XML are very simple and logical.
1. XML Documents Must Have a Root Element
<root>
<child>
<subchild>.....</subchild>
</child>
</root>
eg:
<?xml version="1.0" encoding="UTF-8"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
In the above example <note> is the root element.
<?xml version="1.0" encoding="UTF-8"?> this is called xml prolog.
The XML prolog is optional. If it exists, it must come first in the document.
2. All XML Elements Must Have a Closing Tag.
<p>This is a paragraph.</p>
3. XML Tags are Case Sensitive
XML tags are case sensitive. The tag <Letter> is different from the tag <letter>.
Opening and closing tags must be written with the same case:
<Message>This is a wrong example</message>
<message>This is the right example</message>
4.XML Elements Must be Properly Nested
In XML, all elements must be properly nested within each other:
<b><i>This text is bold and italic</i></b>
In the example above, "Properly nested" simply means that since the <i> element is opened inside the <b> element, it must be closed inside the <b> element.
5.XML Attribute Values Must Always be Quoted
XML elements can have attributes in name/value pairs just like in HTML.
In XML, the attribute values must always be quoted:
<note date="12/11/2007">
<to>Tove</to>
<from>Jani</from>
</note>
6. Entity References
Some characters have a special meaning in XML.
If you place a character like "<" inside an XML element, it will generate an error because the parser interprets it as the start of a new element.
This will generate an XML error:
<message>salary < 1000</message>
To avoid this error, replace the "<" character with an entity reference:
<message>salary < 1000</message>
There are 5 pre-defined entity references in XML:
7.Comments in XML
The syntax for writing comments in XML is similar to that of HTML:
<!-- This is a comment -->
Two dashes in the middle of a comment are not allowed:
<!-- This is an invalid -- comment -->
< < less than > > greater than & & ampersand ' ' apostrophe " " quotation mark7.Comments in XML
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