What Is XML?
XML Is A Meta-language
XML is a meta-language, a syntax and structure with
which you define your own language or data structure.
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XML Is Simple
XML consists of three things: Elements with
Attributes organized into a nested (tree)
Structure.
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Create Your Own Tags
XML itself has no tags, you define your own in a DTD
and schema
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Build Your Own Language
Like enterprises share DTDs/schemas to facilitate
sharing and delivery of information
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Flexible
For each discipline, a DTD/schema is developed for
the concepts and vocabulary appropriate to the
discipline
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Strict Syntax
XML syntax is much more strict that the syntax of
HTML.
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All tags have both a begin and and end tag
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No tags may overlap
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All element names are case sensitive
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All attribute values must be enclosed in quotes
XML Is Powerful
XML can manage arbitrarily complex information. Any type
of database can be represented in XML.
- XML Is Inefficient
Because XML is written in text characters rather than
more efficient binary formats database products use,
XML files tend to be large and do not transfer as
efficiently as conventional electronic data interchange
formats. For this reason, XML is best used for relatively
small datasets (a few megabytes), such as in business to
business (B2B) applications.
XML Can Be Processed Very Efficiently
XML files have strict structure and are concisely defined
in schemas, making them very easy to process.
- Programs For XML Can Be Small
Despite the fact that XML can represent very large,
complex data sets, it can be processed by remarkably
small "recursive" programs: A 20 line JavaScript program
can traverse any XML file ever written, quickly accessing
any data element in the XML database.
- Programs For XML Can Be Difficult
Recursive programs call themselves over and over as they
move through the tree structure of an XML file, a process
that can be hard to understand.
Resources
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