XML Tutorial w3school

XML stands for eXtensible Markup Language.

XML was designed to store and transport data.

XML was designed to be both human- and machine-readable.

XML Example 1

<?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>

Display the XML File » Display the XML File as a Note »

XML Example 2

<?xml version="1.0" encoding="UTF-8"?>
<breakfast_menu>
<food>
    <name>Belgian Waffles</name>
    <price>$5.95</price>
    <description>
   Two of our famous Belgian Waffles with plenty of real maple syrup
   </description>
    <calories>650</calories>
</food>
<food>
    <name>Strawberry Belgian Waffles</name>
    <price>$7.95</price>
    <description>
    Light Belgian waffles covered with strawberries and whipped cream
    </description>
    <calories>900</calories>
</food>
<food>
    <name>Berry-Berry Belgian Waffles</name>
    <price>$8.95</price>
    <description>
    Belgian waffles covered with assorted fresh berries and whipped cream
    </description>
    <calories>900</calories>
</food>
<food>
    <name>French Toast</name>
    <price>$4.50</price>
    <description>
    Thick slices made from our homemade sourdough bread
    </description>
    <calories>600</calories>
</food>
<food>
    <name>Homestyle Breakfast</name>
    <price>$6.95</price>
    <description>
    Two eggs, bacon or sausage, toast, and our ever-popular hash browns
    </description>
    <calories>950</calories>
</food>
</breakfast_menu>

Display the XML File » Display with XSLT »

Why Study XML?

XML plays an important role in many different IT systems.

XML is often used for distributing data over the Internet.

It is important (for all types of software developers!) to have a good understanding of XML.

What You Will Learn

This tutorial will give you a solid understanding of:

What is XML?
How does XML work?
How can I use XML?
What can I use XML for?

Important XML Standards

This tutorial will also dig deep into the following important XML standards:

We recommend reading this tutorial, in the sequence listed in the left menu.

Learn by Examples

Examples are better than 1000 words. Examples are often easier to understand than text explanations.

This tutorial supplements all explanations with clarifying "Try it Yourself" examples.

XML is a software- and hardware-independent tool for storing and transporting data.

What is XML?

XML stands for eXtensible Markup Language
XML is a markup language much like HTML
XML was designed to store and transport data
XML was designed to be self-descriptive
XML is a W3C Recommendation

XML Does Not DO Anything

Maybe it is a little hard to understand, but XML does not DO anything.

This note is a note to Tove from Jani, stored as XML:

<note>
  <to>Tove</to>
  <from>Jani</from>
  <heading>Reminder</heading>
  <body>Don't forget me this weekend!</body>
</note>

The XML above is quite self-descriptive:

It has sender information
It has receiver information
It has a heading
It has a message body

But still, the XML above does not DO anything. XML is just information wrapped in tags.

Someone must write a piece of software to send, receive, store, or display it:

Note

To: Tove

From: Jani

Reminder

Don't forget me this weekend!

The Difference Between XML and HTML

XML and HTML were designed with different goals:

XML was designed to carry data - with focus on what data is
HTML was designed to display data - with focus on how data looks
XML tags are not predefined like HTML tags are

XML Does Not Use Predefined Tags

The XML language has no predefined tags.

The tags in the example above (like <to> and <from>) are not defined in any XML standard. These tags are "invented" by the author of the XML document.

HTML works with predefined tags like <p>, <h1>, <table>, etc.

With XML, the author must define both the tags and the document structure.

XML is Extensible

Most XML applications will work as expected even if new data is added (or removed).

Imagine an application designed to display the original version of note.xml (<to> <from> <heading> <body>).

Then imagine a newer version of note.xml with added <date> and <hour> elements, and a removed <heading>.

The way XML is constructed, older version of the application can still work:

<note>
  <date>2015-09-01</date>
  <hour>08:30</hour>
  <to>Tove</to>
  <from>Jani</from>
  <body>Don't forget me this weekend!</body>
</note>

Old Version

Note

To: Tove

From: Jani

Reminder

Don't forget me this weekend!

New Version

Note

To: Tove

From: Jani

Date: 2015-09-01 08:30

Don't forget me this weekend!

XML Simplifies Things

XML simplifies data sharing
XML simplifies data transport
XML simplifies platform changes
XML simplifies data availability

Many computer systems contain data in incompatible formats. Exchanging data between incompatible systems (or upgraded systems) is a time-consuming task for web developers. Large amounts of data must be converted, and incompatible data is often lost.

XML stores data in plain text format. This provides a software- and hardware-independent way of storing, transporting, and sharing data.

XML also makes it easier to expand or upgrade to new operating systems, new applications, or new browsers, without losing data.

With XML, data can be available to all kinds of "reading machines" like people, computers, voice machines, news feeds, etc.

XML is used in many aspects of web development.

XML is often used to separate data from presentation.

XML Separates Data from Presentation

XML does not carry any information about how to be displayed.

The same XML data can be used in many different presentation scenarios.

Because of this, with XML, there is a full separation between data and presentation.

XML is Often a Complement to HTML

In many HTML applications, XML is used to store or transport data, while HTML is used to format and display the same data.

XML Separates Data from HTML

When displaying data in HTML, you should not have to edit the HTML file when the data changes.

With XML, the data can be stored in separate XML files.

With a few lines of JavaScript code, you can read an XML file and update the data content of any HTML page.

Books.xml

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>

  <book category="cooking">
    <title lang="en">Everyday Italian</title>
    <author>Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>

  <book category="children">
    <title lang="en">Harry Potter</title>
    <author>J K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>

  <book category="web">
    <title lang="en">XQuery Kick Start</title>
    <author>James McGovern</author>
    <author>Per Bothner</author>
    <author>Kurt Cagle</author>
    <author>James Linn</author>
    <author>Vaidyanathan Nagarajan</author>
    <year>2003</year>
    <price>49.99</price>
  </book>

  <book category="web" cover="paperback">
    <title lang="en">Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>

</bookstore>

You will learn a lot more about using XML and JavaScript in the DOM section of this tutorial.

Transaction Data

Thousands of XML formats exist, in many different industries, to describe day-to-day data transactions:

Stocks and Shares
Financial transactions
Medical data
Mathematical data
Scientific measurements
News information
Weather services

Example: XML News

XMLNews is a specification for exchanging news and other information.

Using a standard makes it easier for both news producers and news consumers to produce, receive, and archive any kind of news information across different hardware, software, and programming languages.

An example XMLNews document:

<?xml version="1.0" encoding="UTF-8"?>
<nitf>
  <head>
    <title>Colombia Earthquake</title>
  </head>
  <body>
    <headline>
      <hl1>143 Dead in Colombia Earthquake</hl1>
    </headline>
    <byline>
      <bytag>By Jared Kotler, Associated Press Writer</bytag>
    </byline>
    <dateline>
      <location>Bogota, Colombia</location>
      <date>Monday January 25 1999 7:28 ET</date>
    </dateline>
  </body>
</nitf>

Example: XML Weather Service

An XML national weather service from NOAA (National Oceanic and Atmospheric Administration):

<?xml version="1.0" encoding="UTF-8"?>
<current_observation>

<credit>NOAA's National Weather Service</credit>
<credit_URL>http://weather.gov/</credit_URL>

<image>
  <url>http://weather.gov/images/xml_logo.gif</url>
  <title>NOAA's National Weather Service</title>
  <link>http://weather.gov</link>
</image>

<location>New York/John F. Kennedy Intl Airport, NY</location>
<station_id>KJFK</station_id>
<latitude>40.66</latitude>
<longitude>-73.78</longitude>
<observation_time_rfc822>Mon, 11 Feb 2008 06:51:00 -0500 EST
</observation_time_rfc822>

<weather>A Few Clouds</weather>
<temp_f>11</temp_f>
<temp_c>-12</temp_c>
<relative_humidity>36</relative_humidity>
<wind_dir>West</wind_dir>
<wind_degrees>280</wind_degrees>
<wind_mph>18.4</wind_mph>
<wind_gust_mph>29</wind_gust_mph>
<pressure_mb>1023.6</pressure_mb>
<pressure_in>30.23</pressure_in>
<dewpoint_f>-11</dewpoint_f>
<dewpoint_c>-24</dewpoint_c>
<windchill_f>-7</windchill_f>
<windchill_c>-22</windchill_c>
<visibility_mi>10.00</visibility_mi>

<icon_url_base>http://weather.gov/weather/images/fcicons/</icon_url_base>
<icon_url_name>nfew.jpg</icon_url_name>
<disclaimer_url>http://weather.gov/disclaimer.html</disclaimer_url>
<copyright_url>http://weather.gov/disclaimer.html</copyright_url>

</current_observation>

XML documents form a tree structure that starts at "the root" and branches to "the leaves".

The XML Tree Structure

An Example XML Document

The image above represents books in this XML:

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book category="cooking">
    <title lang="en">Everyday Italian</title>
    <author>Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>
  <book category="children">
    <title lang="en">Harry Potter</title>
    <author>J K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>
</bookstore>

XML Tree Structure

XML documents are formed as element trees.

An XML tree starts at a root element and branches from the root to child elements.

All elements can have sub elements (child elements):

<root>
  <child>
    <subchild>.....</subchild>
  </child>
</root>

The terms parent, child, and sibling are used to describe the relationships between elements.

Parents have children. Children have parents. Siblings are children on the same level (brothers and sisters).

All elements can have text content (Harry Potter) and attributes (category="cooking").

Self-Describing Syntax

XML uses a much self-describing syntax.

A prolog defines the XML version and the character encoding:

<?xml version="1.0" encoding="UTF-8"?>

The next line is the root element of the document:

<bookstore>

The next line starts a <book> element:

<book category="cooking">

The <book> elements have 4 child elements: <title>, <author>, <year>, <price>.

<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>

The next line ends the book element:

</book>

You can assume, from this example, that the XML document contains information about books in a bookstore.

The syntax rules of XML are very simple and logical. The rules are easy to learn, and easy to use.

XML Documents Must Have a Root Element

XML documents must contain one root element that is the parent of all other elements:

<root>
  <child>
    <subchild>.....</subchild>
  </child>
</root>

In this example <note> is the root element:

<?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>

The XML Prolog

This line is called the XML prolog:

<?xml version="1.0" encoding="UTF-8"?>

The XML prolog is optional. If it exists, it must come first in the document.

XML documents can contain international characters, like Norwegian øæå or French êèé.

To avoid errors, you should specify the encoding used, or save your XML files as UTF-8.

UTF-8 is the default character encoding for XML documents.

All XML Elements Must Have a Closing Tag

In XML, it is illegal to omit the closing tag. All elements must have a closing tag:

<p>This is a paragraph.</p>
<br />

Note: The XML prolog does not have a closing tag! This is not an error. The prolog is not a part of the XML document.

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 correct</message>

"Opening and closing tags" are often referred to as "Start and end tags". Use whatever you prefer. It is exactly the same thing.

XML Elements Must be Properly Nested

In HTML, you might see improperly nested elements:

<b><i>This text is bold and italic</b></i>

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.

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>

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 &lt; 1000</message>

There are 5 pre-defined entity references in XML:

<	<	less than
>	>	greater than
&	&	ampersand
'	'	apostrophe
"	"	quotation mark

Only < and & are strictly illegal in XML, but it is a good habit to replace > with > as well.

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 -->

White-space is Preserved in XML

XML does not truncate multiple white-spaces (HTML truncates multiple white-spaces to one single white-space):

XML:	Hello Tove
HTML:	Hello Tove

XML Stores New Line as LF

Windows applications store a new line as: carriage return and line feed (CR+LF).

Unix and Mac OSX use LF.

Old Mac systems use CR.

XML stores a new line as LF.

Well Formed XML

XML documents that conform to the syntax rules above are said to be "Well Formed" XML documents.

An XML document contains XML Elements.

What is an XML Element?

An XML element is everything from (including) the element's start tag to (including) the element's end tag.

<price>29.99</price>

An element can contain:

text
attributes
other elements
or a mix of the above

<bookstore>
  <book category="children">
    <title>Harry Potter</title>
    <author>J K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title>Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>
</bookstore>

In the example above:

<title>, <author>, <year>, and <price> have text content because they contain text (like 29.99).

<bookstore> and <book> have element contents, because they contain elements.

<book> has an attribute (category="children").

Empty XML Elements

An element with no content is said to be empty.

In XML, you can indicate an empty element like this:

<element></element>

You can also use a so called self-closing tag:

<element />

The two forms produce identical results in XML software (Readers, Parsers, Browsers).

Empty elements can have attributes.

XML Naming Rules

XML elements must follow these naming rules:

Element names are case-sensitive
Element names must start with a letter or underscore
Element names cannot start with the letters xml (or XML, or Xml, etc)
Element names can contain letters, digits, hyphens, underscores, and periods
Element names cannot contain spaces

Any name can be used, no words are reserved (except xml).

Best Naming Practices

Create descriptive names, like this: <person>, <firstname>, <lastname>.

Create short and simple names, like this: <book_title> not like this: <the_title_of_the_book>.

Avoid "-". If you name something "first-name", some software may think you want to subtract "name" from "first".

Avoid ".". If you name something "first.name", some software may think that "name" is a property of the object "first".

Avoid ":". Colons are reserved for namespaces (more later).

Non-English letters like éòá are perfectly legal in XML, but watch out for problems if your software doesn't support them!

Naming Conventions

Some commonly used naming conventions for XML elements:

Style	Example	Description
Lower case	<firstname>	All letters lower case
Upper case	<FIRSTNAME>	All letters upper case
Snake case	<first_name>	Underscore separates words (commonly used in SQL databases)
Pascal case	<FirstName>	Uppercase first letter in each word (commonly used by C programmers)
Camel case	<firstName>	Uppercase first letter in each word except the first (commonly used in JavaScript)

Tip! Choose your naming style, and be consistent about it!

XML documents often have a corresponding database. A common practice is to use the naming rules of the database for the XML elements.

XML Elements are Extensible

XML elements can be extended to carry more information.

Look at the following XML example:

<note>
  <to>Tove</to>
  <from>Jani</from>
  <body>Don't forget me this weekend!</body>
</note>

Let's imagine that we created an application that extracted the <to>, <from>, and <body> elements from the XML document to produce this output:

MESSAGE

To: Tove
From: Jani

Don't forget me this weekend!

Imagine that the author of the XML document added some extra information to it:

<note>
  <date>2008-01-10</date>
  <to>Tove</to>
  <from>Jani</from>
  <heading>Reminder</heading>
  <body>Don't forget me this weekend!</body>
</note>

Should the application break or crash?

No. The application should still be able to find the <to>, <from>, and <body> elements in the XML document and produce the same output.

This is one of the beauties of XML. It can be extended without breaking applications.

XML elements can have attributes, just like HTML.

Attributes are designed to contain data related to a specific element.

XML Attributes Must be Quoted

Attribute values must always be quoted. Either single or double quotes can be used.

For a person's gender, the <person> element can be written like this:

<person gender="female">

or like this:

<person gender='female'>

If the attribute value itself contains double quotes you can use single quotes, like in this example:

<gangster name='George "Shotgun" Ziegler'>

or you can use character entities:

<gangster name="George &quot;Shotgun&quot; Ziegler">

XML Elements vs. Attributes

Take a look at these two examples:

<person gender="female">
  <firstname>Anna</firstname>
  <lastname>Smith</lastname>
</person>

<person>
  <gender>female</gender>
  <firstname>Anna</firstname>
  <lastname>Smith</lastname>
</person>

In the first example, gender is an attribute. In the last example, gender is an element. Both examples provide the same information.

There are no rules about when to use attributes or when to use elements in XML.

My Favorite Way

The following three XML documents contain exactly the same information:

A date attribute is used in the first example:

<note date="2008-01-10">
  <to>Tove</to>
  <from>Jani</from>
</note>

A <date> element is used in the second example:

<note>
  <date>2008-01-10</date>
  <to>Tove</to>
  <from>Jani</from>
</note>

An expanded <date> element is used in the third example: (THIS IS MY FAVORITE):

<note>
  <date>
    <year>2008</year>
    <month>01</month>
    <day>10</day>
  </date>
  <to>Tove</to>
  <from>Jani</from>
</note>

Avoid XML Attributes?

Some things to consider when using attributes are:

attributes cannot contain multiple values (elements can)
attributes cannot contain tree structures (elements can)
attributes are not easily expandable (for future changes)

Don't end up like this:

<note day="10" month="01" year="2008"
to="Tove" from="Jani" heading="Reminder"
body="Don't forget me this weekend!">
</note>

XML Attributes for Metadata

Sometimes ID references are assigned to elements. These IDs can be used to identify XML elements in much the same way as the id attribute in HTML. This example demonstrates this:

<messages>
  <note id="501">
    <to>Tove</to>
    <from>Jani</from>
    <heading>Reminder</heading>
    <body>Don't forget me this weekend!</body>
  </note>
  <note id="502">
    <to>Jani</to>
    <from>Tove</from>
    <heading>Re: Reminder</heading>
    <body>I will not</body>
  </note>
</messages>

The id attributes above are for identifying the different notes. It is not a part of the note itself.

What I'm trying to say here is that metadata (data about data) should be stored as attributes, and the data itself should be stored as elements.

XML Namespaces provide a method to avoid element name conflicts.

Name Conflicts

In XML, element names are defined by the developer. This often results in a conflict when trying to mix XML documents from different XML applications.

This XML carries HTML table information:

<table>
  <tr>
    <td>Apples</td>
    <td>Bananas</td>
  </tr>
</table>

This XML carries information about a table (a piece of furniture):

<table>
  <name>African Coffee Table</name>
  <width>80</width>
  <length>120</length>
</table>

If these XML fragments were added together, there would be a name conflict. Both contain a <table> element, but the elements have different content and meaning.

A user or an XML application will not know how to handle these differences.

Solving the Name Conflict Using a Prefix

Name conflicts in XML can easily be avoided using a name prefix.

This XML carries information about an HTML table, and a piece of furniture:

<h:table>
  <h:tr>
    <h:td>Apples</h:td>
    <h:td>Bananas</h:td>
  </h:tr>
</h:table>

<f:table>
  <f:name>African Coffee Table</f:name>
  <f:width>80</f:width>
  <f:length>120</f:length>
</f:table>

In the example above, there will be no conflict because the two <table> elements have different names.

XML Namespaces - The xmlns Attribute

When using prefixes in XML, a namespace for the prefix must be defined.

The namespace can be defined by an xmlns attribute in the start tag of an element.

The namespace declaration has the following syntax. xmlns:prefix="URI".

<root>

<h:table xmlns:h="http://www.w3.org/TR/html4/">
  <h:tr>
    <h:td>Apples</h:td>
    <h:td>Bananas</h:td>
  </h:tr>
</h:table>

<f:table xmlns:f="https://www.w3schools.com/furniture">
  <f:name>African Coffee Table</f:name>
  <f:width>80</f:width>
  <f:length>120</f:length>
</f:table>

</root>

In the example above:

The xmlns attribute in the first <table> element gives the h: prefix a qualified namespace.

The xmlns attribute in the second <table> element gives the f: prefix a qualified namespace.

When a namespace is defined for an element, all child elements with the same prefix are associated with the same namespace.

Namespaces can also be declared in the XML root element:

<root xmlns:h="http://www.w3.org/TR/html4/"
xmlns:f="https://www.w3schools.com/furniture">

<h:table>
  <h:tr>
    <h:td>Apples</h:td>
    <h:td>Bananas</h:td>
  </h:tr>
</h:table>

<f:table>
  <f:name>African Coffee Table</f:name>
  <f:width>80</f:width>
  <f:length>120</f:length>
</f:table>

</root>

Note: The namespace URI is not used by the parser to look up information.

The purpose of using an URI is to give the namespace a unique name.

However, companies often use the namespace as a pointer to a web page containing namespace information.

Uniform Resource Identifier (URI)

A Uniform Resource Identifier (URI) is a string of characters which identifies an Internet Resource.

The most common URI is the Uniform Resource Locator (URL) which identifies an Internet domain address. Another, not so common type of URI is the Uniform Resource Name (URN).

Default Namespaces

Defining a default namespace for an element saves us from using prefixes in all the child elements. It has the following syntax:

xmlns="namespaceURI"

This XML carries HTML table information:

<table xmlns="http://www.w3.org/TR/html4/">
  <tr>
    <td>Apples</td>
    <td>Bananas</td>
  </tr>
</table>

This XML carries information about a piece of furniture:

<table xmlns="https://www.w3schools.com/furniture">
  <name>African Coffee Table</name>
  <width>80</width>
  <length>120</length>
</table>

Namespaces in Real Use

XSLT is a language that can be used to transform XML documents into other formats.

The XML document below, is a document used to transform XML into HTML.

The namespace "http://www.w3.org/1999/XSL/Transform" identifies XSLT elements inside an HTML document:

<?xml version="1.0" encoding="UTF-8"?>

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="/">
<html>
<body>
  <h2>My CD Collection</h2>
  <table border="1">
    <tr>
      <th style="text-align:left">Title</th>
      <th style="text-align:left">Artist</th>
    </tr>
    <xsl:for-each select="catalog/cd">
    <tr>
      <td><xsl:value-of select="title"/></td>
      <td><xsl:value-of select="artist"/></td>
    </tr>
    </xsl:for-each>
  </table>
</body>
</html>
</xsl:template>

</xsl:stylesheet>

Raw XML files can be viewed in all major browsers.

Don't expect XML files to be displayed as HTML pages.

Viewing XML Files

<?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>

Look at the XML file above in your browser: note.xml

Most browsers will display an XML document with color-coded elements.

Often a plus (+) or minus sign (-) to the left of the elements can be clicked to expand or collapse the element structure.

To view raw XML source, try to select "View Page Source" or "View Source" from the browser menu.

Note: In Safari 5 (and earlier), only the element text will be displayed. To view the raw XML, you must right click the page and select "View Source".

Viewing an Invalid XML File

If an erroneous XML file is opened, some browsers will report the error, and some will display it, or display it incorrectly.

<?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>

Try to open the following XML file: note_error.xml

Other XML Examples

Viewing some XML documents will help you get the XML feeling:

An XML breakfast menu
This is a breakfast food menu from a restaurant, stored as XML.

An XML CD catalog
This is a CD collection, stored as XML.

An XML plant catalog
This is a plant catalog from a plant shop, stored as XML.

Why Does XML Display Like This?

XML documents do not carry information about how to display the data.

Since XML tags are "invented" by the author of the XML document, browsers do not know if a tag like <table> describes an HTML table or a dining table.

All modern browsers have a built-in XMLHttpRequest object to request data from a server.

The XMLHttpRequest Object

The XMLHttpRequest object can be used to request data from a web server.

The XMLHttpRequest object is a developers dream, because you can:

Update a web page without reloading the page
Request data from a server - after the page has loaded
Receive data from a server - after the page has loaded
Send data to a server - in the background

XMLHttpRequest Example

When you type a character in the input field below, an XMLHttpRequest is sent to the server, and some name suggestions are returned (from the server):

Example

The example above is explained in the AJAX chapters of this tutorial.

Sending an XMLHttpRequest

A common JavaScript syntax for using the XMLHttpRequest object looks much like this:

Example

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
       // Typical action to be performed when the document is ready:
       document.getElementById("demo").innerHTML = xhttp.responseText;
    }
};
xhttp.open("GET", "filename", true);
xhttp.send();

Example Explained

The first line in the example above creates an XMLHttpRequest object:

var xhttp = new XMLHttpRequest();

The onreadystatechange property specifies a function to be executed every time the status of the XMLHttpRequest object changes:

xhttp.onreadystatechange = function()

When readyState property is 4 and the status property is 200, the response is ready:

if (this.readyState == 4 && this.status == 200)

The responseText property returns the server response as a text string.

The text string can be used to update a web page:

document.getElementById("demo").innerHTML = xhttp.responseText;

All major browsers have a built-in XML parser to access and manipulate XML.

XML Parser

The XML DOM (Document Object Model) defines the properties and methods for accessing and editing XML.

However, before an XML document can be accessed, it must be loaded into an XML DOM object.

All modern browsers have a built-in XML parser that can convert text into an XML DOM object.

Parsing a Text String

This example parses a text string into an XML DOM object, and extracts the info from it with JavaScript:

Example

<html>
<body>

<p id="demo"></p>

<script>
var text, parser, xmlDoc;

text = "<bookstore><book>" +
"<title>Everyday Italian</title>" +
"<author>Giada De Laurentiis</author>" +
"<year>2005</year>" +
"</book></bookstore>";

parser = new DOMParser();
xmlDoc = parser.parseFromString(text,"text/xml");

document.getElementById("demo").innerHTML =
xmlDoc.getElementsByTagName("title")[0].childNodes[0].nodeValue;
</script>

</body>
</html>

Try it Yourself »

Example ExplainedA text string is defined:
text = "<bookstore><book>" +
"<title>Everyday Italian</title>" +
"<author>Giada De Laurentiis</author>" +
"<year>2005</year>" +
"</book></bookstore>";
An XML DOM parser is created:
parser = new DOMParser();
The parser creates a new XML DOM object using the text string:
xmlDoc = parser.parseFromString(text,"text/xml");
The XMLHttpRequest ObjectThe XMLHttpRequest Object has a built in XML Parser.
The responseText property returns the response as a string.
The responseXML property returns the response as an XML DOM object.
If you want to use the response as an XML DOM object, you can use the responseXML property.
ExampleRequest the file cd_catalog.xml and use the response as an XML DOM object:
xmlDoc = xmlhttp.responseXML;
txt = "";
x = xmlDoc.getElementsByTagName("ARTIST");
for (i = 0; i < x.length; i++) {
    txt += x[i].childNodes[0].nodeValue + "<br>";
}
document.getElementById("demo").innerHTML = txt;
Try it Yourself »

What is the DOM?

The Document Object Model (DOM) defines a standard for accessing and manipulating documents:

"The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document."

The HTML DOM defines a standard way for accessing and manipulating HTML documents. It presents an HTML document as a tree-structure.

The XML DOM defines a standard way for accessing and manipulating XML documents. It presents an XML document as a tree-structure.

Understanding the DOM is a must for anyone working with HTML or XML.

The HTML DOM

All HTML elements can be accessed through the HTML DOM.

This example changes the value of an HTML element with id="demo":

Example

<h1 id="demo">This is a Heading</h1>

<button type="button"
onclick="document.getElementById('demo').innerHTML = 'Hello World!'">Click Me!
</button>

Try it Yourself »

What is XPath?

XPath is a major element in the XSLT standard.

XPath can be used to navigate through elements and attributes in an XML document.

XPath is a syntax for defining parts of an XML document
XPath uses path expressions to navigate in XML documents
XPath contains a library of standard functions
XPath is a major element in XSLT and in XQuery
XPath is a W3C recommendation

XPath Path Expressions

XPath uses path expressions to select nodes or node-sets in an XML document. These path expressions look very much like the expressions you see when you work with a traditional computer file system.

XPath expressions can be used in JavaScript, Java, XML Schema, PHP, Python, C and C++, and lots of other languages.

XPath is Used in XSLT

XPath is a major element in the XSLT standard.

With XPath knowledge you will be able to take great advantage of XSL.

XPath Example

We will use the following XML document:

<?xml version="1.0" encoding="UTF-8"?>

<bookstore>

<book category="cooking">
  <title lang="en">Everyday Italian</title>
  <author>Giada De Laurentiis</author>
  <year>2005</year>
  <price>30.00</price>
</book>

<book category="children">
  <title lang="en">Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>

<book category="web">
  <title lang="en">XQuery Kick Start</title>
  <author>James McGovern</author>
  <author>Per Bothner</author>
  <author>Kurt Cagle</author>
  <author>James Linn</author>
  <author>Vaidyanathan Nagarajan</author>
  <year>2003</year>
  <price>49.99</price>
</book>

<book category="web">
  <title lang="en">Learning XML</title>
  <author>Erik T. Ray</author>
  <year>2003</year>
  <price>39.95</price>
</book>

</bookstore>

In the table

With XSLT you can transform an XML document into HTML.

Displaying XML with XSLT

XSLT (eXtensible Stylesheet Language Transformations) is the recommended style sheet language for XML.

XSLT is far more sophisticated than CSS. With XSLT you can add/remove elements and attributes to or from the output file. You can also rearrange and sort elements, perform tests and make decisions about which elements to hide and display, and a lot more.

XSLT uses XPath to find information in an XML document.

XSLT Example

We will use the following XML document:

<?xml version="1.0" encoding="UTF-8"?>

<breakfast_menu>

<food>

<name>Belgian Waffles</name>

<description>Two of our famous Belgian Waffles with plenty of real maple syrup</description>

</food>

<food>

<name>Strawberry Belgian Waffles</name>

<description>Light Belgian waffles covered with strawberries and whipped cream</description>

</food>

<food>

<name>Berry-Berry Belgian Waffles</name>

<description>Light Belgian waffles covered with an assortment of fresh berries and whipped cream</description>

</food>

<food>

<name>French Toast</name>

<description>Thick slices made from our homemade sourdough bread</description>

</food>

<food>

<name>Homestyle Breakfast</name>

<description>Two eggs, bacon or sausage, toast, and our ever-popular hash browns</description>

</food>

</breakfast_menu>

Use XSLT to transform XML into HTML, before it is displayed in a browser:

Example XSLT Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<html xsl:version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<body style="font-family:Arial;font-size:12pt;background-color:#EEEEEE">
<xsl:for-each select="breakfast_menu/food">
  <div style="background-color:teal;color:white;padding:4px">
    <span style="font-weight:bold"><xsl:value-of select="name"/> - </span>
    <xsl:value-of select="price"/>
    </div>
  <div style="margin-left:20px;margin-bottom:1em;font-size:10pt">
    <p>
    <xsl:value-of select="description"/>
    <span style="font-style:italic"> (<xsl:value-of select="calories"/> calories per serving)</span>
    </p>
  </div>
</xsl:for-each>
</body>
</html>

Transform the XML Document with XSLT »

What is XQuery?

XQuery is to XML what SQL is to databases.

XQuery was designed to query XML data.

XQuery Example

for $x in doc("books.xml")/bookstore/book
where $x/price>30
order by $x/title
return $x/title

What is XQuery?

XQuery is the language for querying XML data
XQuery for XML is like SQL for databases
XQuery is built on XPath expressions
XQuery is supported by all major databases
XQuery is a W3C Recommendation

XQuery is About Querying XML

XQuery is a language for finding and extracting elements and attributes from XML documents.

Here is an example of what XQuery could solve:

"Select all CD records with a price less than $10 from the CD collection stored in cd_catalog.xml"

XQuery and XPath

XQuery 1.0 and XPath 2.0 share the same data model and support the same functions and operators. If you have already studied XPath you will have no problems with understanding XQuery.

XQuery - Examples of Use

XQuery can be used to:

Extract information to use in a Web Service
Generate summary reports
Transform XML data to XHTML
Search Web documents for relevant information

XQuery is a W3C Recommendation

XQuery is compatible with several W3C standards, such as XML, Namespaces, XSLT, XPath, and XML Schema.

XQuery 1.0 became a W3C Recommendation in 2007.

XLink is used to create hyperlinks in XML documents.

XLink is used to create hyperlinks within XML documents
Any element in an XML document can behave as a link
With XLink, the links can be defined outside the linked files
XLink is a W3C Recommendation

XLink Browser Support

There is no browser support for XLink in XML documents.

However, all major browsers support XLinks in SVG.

XLink Syntax

In HTML, the <a> element defines a hyperlink. However, this is not how it works in XML. In XML documents, you can use whatever element names you want - therefore it is impossible for browsers to predict what link elements will be called in XML documents.

Below is a simple example of how to use XLink to create links in an XML document:

<?xml version="1.0" encoding="UTF-8"?>

<homepages xmlns:xlink="http://www.w3.org/1999/xlink">
  <homepage xlink:type="simple" xlink:href="https://www.w3schools.com">Visit W3Schools</homepage>
  <homepage xlink:type="simple" xlink:href="http://www.w3.org">Visit W3C</homepage>
</homepages>

To get access to the XLink features we must declare the XLink namespace. The XLink namespace is: "http://www.w3.org/1999/xlink".

The xlink:type and the xlink:href attributes in the <homepage> elements come from the XLink namespace.

The xlink:type="simple" creates a simple "HTML-like" link (means "click here to go there").

The xlink:href attribute specifies the URL to link to.

XLink Example

The following XML document contains XLink features:

<?xml version="1.0" encoding="UTF-8"?>

<bookstore xmlns:xlink="http://www.w3.org/1999/xlink">

<book title="Harry Potter">
  <description
  xlink:type="simple"
  xlink:href="/images/HPotter.gif"
  xlink:show="new">
  As his fifth year at Hogwarts School of Witchcraft and
  Wizardry approaches, 15-year-old Harry Potter is.......
  </description>
</book>

<book title="XQuery Kick Start">
  <description
  xlink:type="simple"
  xlink:href="/images/XQuery.gif"
  xlink:show="new">
  XQuery Kick Start delivers a concise introduction
  to the XQuery standard.......
  </description>
</book>

</bookstore>

Example explained:

The XLink namespace is declared at the top of the document (xmlns:xlink="http://www.w3.org/1999/xlink")
The xlink:type="simple" creates a simple "HTML-like" link
The xlink:href attribute specifies the URL to link to (in this case - an image)
The xlink:show="new" specifies that the link should open in a new window

XPointer

XPointer allows links to point to specific parts of an XML document
XPointer uses XPath expressions to navigate in the XML document
XPointer is a W3C Recommendation

XPointer Browser Support

There is no browser support for XPointer. But XPointer is used in other XML languages.

XPointer Example

In this example, we will use XPointer in conjunction with XLink to point to a specific part of another document.

We will start by looking at the target XML document (the document we are linking to):

<?xml version="1.0" encoding="UTF-8"?>

<dogbreeds>

<dog breed="Rottweiler" id="Rottweiler">
  <picture url="https://dog.com/rottweiler.gif" />
  <history>The Rottweiler's ancestors were probably Roman
  drover dogs.....</history>
  <temperament>Confident, bold, alert and imposing, the Rottweiler
  is a popular choice for its ability to protect....</temperament>
</dog>

<dog breed="FCRetriever" id="FCRetriever">
  <picture url="https://dog.com/fcretriever.gif" />
  <history>One of the earliest uses of retrieving dogs was to
  help fishermen retrieve fish from the water....</history>
  <temperament>The flat-coated retriever is a sweet, exuberant,
  lively dog that loves to play and retrieve....</temperament>
</dog>

</dogbreeds>

Note that the XML document above uses id attributes on each element!

So, instead of linking to the entire document (as with XLink), XPointer allows you to link to specific parts of the document. To link to a specific part of a page, add a number sign (#) and an XPointer expression after the URL in the xlink:href attribute, like this: xlink:href="https://dog.com/dogbreeds.xml#xpointer(id('Rottweiler'))". The expression refers to the element in the target document, with the id value of "Rottweiler".

XPointer also allows a shorthand method for linking to an element with an id. You can use the value of the id directly, like this: xlink:href="https://dog.com/dogbreeds.xml#Rottweiler".

The following XML document contains links to more information of the dog breed for each of my dogs:

<?xml version="1.0" encoding="UTF-8"?>

<mydogs xmlns:xlink="http://www.w3.org/1999/xlink">

<mydog>
  <description>
  Anton is my favorite dog. He has won a lot of.....
  </description>
  <fact xlink:type="simple" xlink:href="https://dog.com/dogbreeds.xml#Rottweiler">
  Fact about Rottweiler
  </fact>
</mydog>

<mydog>
  <description>
  Pluto is the sweetest dog on earth......
  </description>
  <fact xlink:type="simple" xlink:href="https://dog.com/dogbreeds.xml#FCRetriever">
  Fact about flat-coated Retriever
  </fact>
</mydog>

</mydogs>

Use our XML validator to syntax-check your XML.

Well Formed XML Documents

An XML document with correct syntax is called "Well Formed".

The syntax rules were described in the previous chapters:

XML documents must have a root element
XML elements must have a closing tag
XML tags are case sensitive
XML elements must be properly nested
XML attribute values must be quoted

<?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>

XML Errors Will Stop You

Errors in XML documents will stop your XML applications.

The W3C XML specification states that a program should stop processing an XML document if it finds an error. The reason is that XML software should be small, fast, and compatible.

HTML browsers are allowed to display HTML documents with errors (like missing end tags).

With XML, errors are not allowed.

Syntax-Check Your XML

To help you syntax-check your XML, we have created an XML validator.

Try to syntax-check correct XML :

Try to syntax-check incorrect XML :

Try to syntax-check your own XML :

Valid XML Documents

A "well formed" XML document is not the same as a "valid" XML document.

A "valid" XML document must be well formed. In addition, it must conform to a document type definition.

There are two different document type definitions that can be used with XML:

DTD - The original Document Type Definition
XML Schema - An XML-based alternative to DTD

A document type definition defines the rules and the legal elements and attributes for an XML document.

An XML document with correct syntax is called "Well Formed".

An XML document validated against a DTD is both "Well Formed" and "Valid".

What is a DTD?

DTD stands for Document Type Definition.

A DTD defines the structure and the legal elements and attributes of an XML document.

Valid XML Documents

A "Valid" XML document is "Well Formed", as well as it conforms to the rules of a DTD:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE note SYSTEM "Note.dtd">
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>

The DOCTYPE declaration above contains a reference to a DTD file. The content of the DTD file is shown and explained below.

XML DTD

The purpose of a DTD is to define the structure and the legal elements and attributes of an XML document:

Note.dtd:

<!DOCTYPE note
[
<!ELEMENT note (to,from,heading,body)>
<!ELEMENT to (#PCDATA)>
<!ELEMENT from (#PCDATA)>
<!ELEMENT heading (#PCDATA)>
<!ELEMENT body (#PCDATA)>
]>

The DTD above is interpreted like this:

!DOCTYPE note - Defines that the root element of the document is note
!ELEMENT note - Defines that the note element must contain the elements: "to, from, heading, body"
!ELEMENT to - Defines the to element to be of type "#PCDATA"
!ELEMENT from - Defines the from element to be of type "#PCDATA"
!ELEMENT heading - Defines the heading element to be of type "#PCDATA"
!ELEMENT body - Defines the body element to be of type "#PCDATA"

Using DTD for Entity Declaration

A DOCTYPE declaration can also be used to define special characters or strings, used in the document:

Example

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE note [
<!ENTITY nbsp "&#xA0;">
<!ENTITY writer "Writer: Donald Duck.">
<!ENTITY copyright "Copyright: W3Schools.">
]>

<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
<footer>&writer;&nbsp;&copyright;</footer>
</note>

Try it Yourself »

Tip: An entity has three parts: it starts with an ampersand (&), then comes the entity name, and it ends with a semicolon (;).

When to Use a DTD?

With a DTD, independent groups of people can agree to use a standard DTD for interchanging data.

With a DTD, you can verify that the data you receive from the outside world is valid.

You can also use a DTD to verify your own data.

If you want to study DTD, please read our DTD Tutorial.

When NOT to Use a DTD?

XML does not require a DTD.

When you are experimenting with XML, or when you are working with small XML files, creating DTDs may be a waste of time.

If you develop applications, wait until the specification is stable before you add a DTD. Otherwise, your software might stop working because of validation errors.

An XML Schema describes the structure of an XML document, just like a DTD.

An XML document with correct syntax is called "Well Formed".

An XML document validated against an XML Schema is both "Well Formed" and "Valid".

XML Schema

XML Schema is an XML-based alternative to DTD:

<xs:element name="note">

<xs:complexType>
  <xs:sequence>
    <xs:element name="to" type="xs:string"/>
    <xs:element name="from" type="xs:string"/>
    <xs:element name="heading" type="xs:string"/>
    <xs:element name="body" type="xs:string"/>
  </xs:sequence>
</xs:complexType>

</xs:element>

The Schema above is interpreted like this:

<xs:element name="note"> defines the element called "note"
<xs:complexType> the "note" element is a complex type
<xs:sequence> the complex type is a sequence of elements
<xs:element name="to" type="xs:string"> the element "to" is of type string (text)
<xs:element name="from" type="xs:string"> the element "from" is of type string
<xs:element name="heading" type="xs:string"> the element "heading" is of type string
<xs:element name="body" type="xs:string"> the element "body" is of type string

XML Schemas are More Powerful than DTD

XML Schemas are written in XML
XML Schemas are extensible to additions
XML Schemas support data types
XML Schemas support namespaces

Why Use an XML Schema?

With XML Schema, your XML files can carry a description of its own format.

With XML Schema, independent groups of people can agree on a standard for interchanging data.

With XML Schema, you can verify data.

XML Schemas Support Data Types

One of the greatest strengths of XML Schemas is the support for data types:

It is easier to describe document content
It is easier to define restrictions on data
It is easier to validate the correctness of data
It is easier to convert data between different data types

XML Schemas use XML Syntax

Another great strength about XML Schemas is that they are written in XML:

You don't have to learn a new language
You can use your XML editor to edit your Schema files
You can use your XML parser to parse your Schema files
You can manipulate your Schemas with the XML DOM
You can transform your Schemas with XML files are plain text files just like HTML files.
XML can easily be stored and generated by a standard web server.
Storing XML Files on the Server
XML files can be stored on an Internet server exactly the same way as HTML files.
Start Windows Notepad and write the following lines:
<?xml version="1.0" encoding="UTF-8"?>
<note>
  <from>Jani</from>
  <to>Tove</to>
  <message>Remember me this weekend</message>
</note>
Save the file on your web server with a proper name like "note.xml".
Generating XML with PHP
XML can be generated on a server without any installed XML software.
To generate an XML response from the server using PHP, use following code:
<?php
header("Content-type: text/xml");
echo "<?xml version='1.0' encoding='UTF-8'?>";
echo "<note>";
echo "<from>Jani</from>";
echo "<to>Tove</to>";
echo "<message>Remember me this weekend</message>";
echo "</note>";
?>
Note that the content type of the response header must be set to "text/xml".

Generating XML with ASP

To generate an XML response from the server - simply write the following code and save it as an ASP file on the web server:

<%
response.ContentType="text/xml"
response.Write("<?xml version='1.0' encoding='UTF-8'?>")
response.Write("<note>")
response.Write("<from>Jani</from>")
response.Write("<to>Tove</to>")
response.Write("<message>Remember me this weekend</message>")
response.Write("</note>")
%>

Note that the content type of the response must be set to "text/xml".

See how the ASP file will be returned from the server.

If you want to study ASP, you will find our ASP tutorial on our homepage.

Generating XML From a Database

XML can be generated from a database without any installed XML software.

To generate an XML database response from the server, simply write the following code and save it as an ASP file on the web server:

<%
response.ContentType = "text/xml"
set conn=Server.CreateObject("ADODB.Connection")
conn.provider="Microsoft.Jet.OLEDB.4.0;"
conn.open server.mappath("/datafolder/database.mdb")

sql="select fname,lname from tblGuestBook"
set rs=Conn.Execute(sql)

response.write("<?xml version='1.0' encoding='UTF-8'?>")
response.write("<guestbook>")
while (not rs.EOF)
response.write("<guest>")
response.write("<fname>" & rs("fname") & "</fname>")
response.write("<lname>" & rs("lname") & "</lname>")
response.write("</guest>")
rs.MoveNext()
wend

rs.close()
conn.close()
response.write("</guestbook>")
%>

See the real life database output from the ASP file above.

The example above uses ASP with ADO.

If you want to study ASP and ADO, you will find the tutorials on our homepage.

Transforming XML with XSLT on the Server

This ASP transforms an XML file to XHTML on the server:

<%
'Load XML
set xml = Server.CreateObject("Microsoft.XMLDOM")
xml.async = false
xml.load(Server.MapPath("simple.xml"))

'Load XSL
set xsl = Server.CreateObject("Microsoft.XMLDOM")
xsl.async = false
xsl.load(Server.MapPath("simple.xsl"))

'Transform file
Response.Write(xml.transformNode(xsl))
%>

Example explained

The first block of code creates an instance of the Microsoft XML parser (XMLDOM), and loads the XML file into memory.
The second block of code creates another instance of the parser and loads the XSL file into memory.
The last line of code transforms the XML document using the XSL document, and sends the result as XHTML to your browser. Nice!

NOTE: THESE CONTENT HAS BEEN TAKEN FROM W3SCHOOL

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XML Tutorial w3school

XML Example 1

XML Example 2

Why Study XML?

What You Will Learn

Important XML Standards

Learn by Examples

What is XML?

XML Does Not DO Anything

Note

Reminder

The Difference Between XML and HTML

XML Does Not Use Predefined Tags

XML is Extensible

Old Version

Note

Reminder

New Version

Note

XML Simplifies Things

XML Separates Data from Presentation

XML is Often a Complement to HTML

XML Separates Data from HTML

Books.xml

Transaction Data

Example: XML News

Example: XML Weather Service

The XML Tree Structure

An Example XML Document

XML Tree Structure

Self-Describing Syntax

XML Documents Must Have a Root Element

The XML Prolog

All XML Elements Must Have a Closing Tag

XML Tags are Case Sensitive

XML Elements Must be Properly Nested

XML Attribute Values Must Always be Quoted

Entity References

Comments in XML

White-space is Preserved in XML

XML Stores New Line as LF

Well Formed XML

What is an XML Element?

Empty XML Elements

XML Naming Rules

Best Naming Practices

Naming Conventions

XML Elements are Extensible

XML Attributes Must be Quoted

XML Elements vs. Attributes

My Favorite Way

Avoid XML Attributes?

XML Attributes for Metadata

Name Conflicts

Solving the Name Conflict Using a Prefix

XML Namespaces - The xmlns Attribute

Uniform Resource Identifier (URI)

Default Namespaces

Namespaces in Real Use

Viewing XML Files

Viewing an Invalid XML File

Other XML Examples

Why Does XML Display Like This?

The XMLHttpRequest Object

XMLHttpRequest Example

Example

Sending an XMLHttpRequest

Example

Example Explained

XML Parser

Parsing a Text String

Example

Example Explained

The XMLHttpRequest Object

Example

What is the DOM?

The HTML DOM

Example

What is XPath?