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CREATING AN XML DOCUMENT
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INTRODUCING XML
• XML stands for Extensible Markup Language. A
markup language specifies the structure and
content of a document.
• Because it is extensible, XML can be used to
create a wide variety of document types.
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INTRODUCING XML
• XML is a subset of the Standard Generalized
Markup Language (SGML) which was introduced
in the 1980s. SGML is very complex and can be
costly. These reasons led to the creation of
Hypertext Markup Language (HTML), a more
easily used markup language. XML can be seen as
sitting between SGML and HTML – easier to
learn than SGML, but more robust than HTML.
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THE LIMITS OF HTML
• HTML was designed for formatting text on a Web page. It
was not designed for dealing with the content of a Web
page. Additional features have been added to HTML, but
they do not solve data description or cataloging issues in
an HTML document.
• Because HTML is not extensible, it cannot be modified to
meet specific needs. Browser developers have added
features making HTML more robust, but this has resulted
in a confusing mix of different HTML standards.
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XML VOCABULARIES
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WELL-FORMED AND VALID XML
DOCUMENTS
• An XML document is well-formed if it contains
no syntax errors and fulfills all of the
specifications for XML code as defined by the
W3C.
• An XML document is valid if it is well-formed
and also satisfies the rules laid out in the DTD or
schema attached to the document.
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THE STRUCTURE OF AN XMLXP
DOCUMENT
• XML documents consist of three parts
– Prolog: optional and information about the
document itself
– Document body: the document’s content in a
hierarchical tree structure
– Epilog: optional and any final comments or
processing instructions
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THE STRUCTURE OF AN XMLXP
DOCUMENT:
THE XML DECLARATION
• The XML declaration is always the first line of code in an
XML document. It tells the processor what follows is
written using XML. It can also provide any information
about how the parser should interpret the code.
• The complete syntax is:
<?xml version=“version number” encoding=“encoding
type” standalone=“yes | no” ?>
• A sample declaration might look like this:
<?xml version=“1.0” encoding=“UTF-8”
standalone=“yes” ?>
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THE STRUCTURE OF AN XMLXP
DOCUMENT:
INSERTING COMMENTS
• Comments or miscellaneous statements go after
the declaration. Comments may appear anywhere
after the declaration.
• The syntax for comments is:
<!- - comment text - ->
• This is the same syntax for HTML comments
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ELEMENT
• Element names are case sensitive
• Elements can be nested, as follows:
<tracks>Kind of Blue
<track>So What ((:22)</track>
<track>Blue in Green (5:37)</track>
</tracks>
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WORKING WITH ATTRIBUTES
• An attribute is a feature or characteristic of an
element. Attributes are text strings and must be
placed in single or double quotes. The syntax is:
<element_name attribute=“value”> …
</element_name>
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ELEMENTS AND ATTRIBUTES: XP
ADDING ELEMENTS TO THE
JAZZ.XML FILE
document
elements
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CHARACTER REFERENCES
This figure shows commonly used character reference numbers
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CDATA SECTIONS
• A CDATA section is a large block of text the
XML processor will interpret only as text.
• The syntax to create a CDATA section is:
<! [CDATA [
Text Block
] ]>
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CDATA SECTIONS
• In this example, a CDATA section stores several HTML
tags within an element named HTMLCODE:
<htmlcode>
<![CDATA[
<h1>The Jazz Warehouse</h1>
<h2>Your Online Store for Jazz Music</h2>
] ]>
</htmlcode>
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CDATA SECTIONS
This figure shows the revised Jazz.XML file
CDATA section
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PARSING AN XML DOCUMENT
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LINKING TO A STYLE SHEET
• Link the XML document to a style sheet to format
the document. The XML processor will combine
the style sheet with the XML document and apply
any formatting codes defined in the style sheet to
display a formatted document.
• There are two main style sheet languages used
with XML:
– Cascading Style Sheets (CSS) and Extensible
Style Sheets (XSL)
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LINKING TO A STYLE SHEET
• There are some important benefits to using style
sheets:
– By separating content from format, you can
concentrate on the appearance of the document
– Different style sheets can be applied to the
same XML document
– Any style sheet changes will be automatically
reflected in any Web page based upon the style
sheet
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APPLYING A STYLE TO AN
ELEMENT
XP
• To apply a style sheet to a document, use the following
syntax:
selector {attribute1:value1; attribute2:value2; …}
• selector is an element (or set of elements) from the XML
document.
• attribute and value are the style attributes and attribute
values to be applied to the document.
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CREATING PROCESSING
INSTRUCTIONS
• The link from the XML document to a style sheet
is created using a processing statement.
• A processing instruction is a command that gives
instructions to the XML parser.
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CREATING PROCESSING
INSTRUCTIONS
XP
• For example:
<?xml-stylesheet type=“style” href=“sheet” ?>
• Style is the type of style sheet to access and sheet
is the name and location of the style sheet.
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THE JW.CSS STYLE SHEET
This figure shows the cascading style sheet stored in the jw.css file
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LINKING TO THE JW.CSS
STYLE SHEET
XP
This figure shows how to link the JW.css style sheet to the Jazz.xml file
processing instruction to
access the jw.css style sheet
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THE JAZZ.XML DOCUMENT XP
FORMATTED WITH THE JW.CSS
STYLE SHEET
This figure shows the
formatted jazz.xml file
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WORKING WITH XSLT
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GENERATING A RESULT
DOCUMENT
XP
• An XSLT style sheet converts a source document of
XML content into a result document by using the
XSLT processor
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CREATING AN XSLT STYLE SHEET
• To create an XSLT style sheet, the general structure:
<?xml version =“1.0”>
<xsl:stylesheet version = “1.0”
xmlns:xsl =“http://www.w3.org/1999/XSL/Transform”>
Content of the style sheet
</xsl:stylesheet>
The <xsl:stylesheet> tag can be substituted for the
<xsl:transform> tag
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WORKING WITH DOCUMENT
NODES
XP
• Under XPath, each component in the document is
referred to as a node, and the entire structure of the
document is a node tree
• The node tree consists of the following objects:
– the source document itself
– comments
– processing instructions
– namespaces
– elements,
– element text
– element attributes
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NODE TREE EXAMPLE
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RELATIVE PATHS
• With a relative path, the location of the node is
indicated relative to a specific node in the tree called
the context node
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USING XPATH TO REFERENCEXP
A NODE
• For absolute path, XPath begins with the root node,
identified by a forward slash and proceeds down the
levels of the node tree
• An absolute path: /child1/child2/child3/…
• To reference an element without regard to its location
in the node tree, use a double forward slash with the
name of the descendant node
• A relative path : //descendant
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REFERENCING GROUPS OF
ELEMENTS
XP
• XPath allows you to refer to groups of nodes by using the
wildcard character (*)
• To select all of the nodes in the node tree, you can use
the path:
//*
The (*) symbol matches any node, and the (//)symbol
matches any level of the node tree
Example: /portfolio/stock/*
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REFERENCING ATTRIBUTE
NODES
XP
• XPath uses different notation to refer to attribute
nodes
• The syntax for attribute node is:
@attribute
where attribute is the name of the attribute
Example: /portfolio/stock/name/@symbol
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WORKING WITH TEXT NODES
• The text contained in an element node is treated as a
text node
• The syntax for referencing a text node is:
text()
• To match all text nodes in the document, use:
//text()
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CREATING THE ROOT TEMPLATE
• A template is a collection of elements that define how
a particular section of the source document should be
transformed in the result document
• The root template sets up the initial code for the result
document
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CREATING A TEMPLATE
• To create a template, the syntax is:
<xsl:template match=“node set”>
styles
</xsl:template>
–where node set is an XPath expression that
references a node set from the source document
and styles are the XSLT styles applied to those
nodes
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CREATING A ROOT TEMPLATE
• To create a root template, the syntax is:
<xsl:template match=“/”>
styles
</xsl:template>
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EXTRACTING ELEMENT VALUES
• To insert a node’s value into the result document, the
syntax is:
– <xsl:value-of> select=“expression” />
– where expression is an expression that identifies the
node from the source document’s node tree
• If the node contains child elements in addition to text
content, the text in those child nodes appears as well
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INSERTING A NODE VALUE XP
EXAMPLE
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PROCESSING SEVERAL
ELEMENTS
XP
• To process a batch of nodes, the syntax is:
<xsl:for-each select=“expression” />
styles
</xsl:for-each>
where expression is an expression that defines
the group of nodes to which the XSLT and
literal result elements are applied
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PROCESSING SEVERAL
ELEMENTS
XP
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WORKING WITH TEMPLATES
• To apply a template in the result document, use the
XSLT element
– <xsl:apply-templates select=“expression” />
where expression indicates the node template to
be applied
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CREATING THE STOCK
TEMPLATE EXAMPLE
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SORTING NODE SETS
• By default, nodes are processed in document order,
by their appearance in the document
• To specify a different order, XSLT provides the
<xsl:sort> element
• This element can be used with either the <xsl:applytemplates> or the <xsl:for-each> element
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SORTING NODE SETS
• The <xsl:sort> element contains several attributes to
control how the XSLT process sorts the nodes in the
source document
– The select attribute determines the criteria under
which the context node is sorted
– The data-type attribute indicates the type of data
– The order attribute indicates the direction of the
sorting (ascending or descending)
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