XML Elements
XML Elements are extensible. They have relationships. They have simple naming rules.
XML Elements are Extensible
XML documents can be extended to carry more information.
Look at the following XML example:
<?xml version="1.0" encoding="ISO-8859-1"?> <E-mail> <To>Rohan</To> <From>Amit</From> <Body>Be ready for a cruise...i will catch u tonight</Body> </E-mail> |
Let's suppose that we create an application to fetch data from the above XML document and produce this output:
| E-mail
To: Rohan Be ready for a cruise...i will catch u tonight |
Now, the author wants to add a new feature (let it be a subject line). He can easily achieve it by adding one more tag ie..<Subject>in the xml document. So the new modified xml document will look like this :
| <?xml version="1.0"
encoding="ISO-8859-1"?> <E-mail> <To>Rohan</To> <From>Amit</From> <Subject>Surprise....</Subject> <Body>Be ready for a cruise...i will catch u tonight</Body> </E-mail> |
Now the new generated output will look like this
| E-mail
To: Rohan Subject : Surprise.... Be ready for a cruise...i will catch u tonight |
XML Elements have Relationships
Elements in a xml document are related as parents and children.
Imagine that this xml document is a description of a e-mail:
| <?xml version="1.0"
encoding="ISO-8859-1"?> <E-mail> <To>Rohan</To> <From>Amit</From> <Subject>Surprise....</Subject> <Body>Be ready for a cruise...i will catch u tonight</Body> </E-mail> |
Here, E-mail is the root element while To, From, Subject and Body are the child elements of the E-mail. Here, E-mail is the parent element of To, From, Subject and Body. To, From, Subject and Body are siblings (or sister elements) because they have the same parentage. Hence , all the XML Elements have Relationships.
XML Element Naming : Know-hows
XML elements must follow these naming conventions:
Names must not start with a number or punctuation character but it can contain letters, numbers, and other characters without spaces. Names must not start with the letters xml (or XML, or Xml, etc)