15.1. eXtensible Markup Language - XML¶

XML is a mark-up language. HTML is also a mark-up language. XML looks very similar to HTML, but it is different from XML.

Some of the differences between XML and HTML are:

XML is used to store and transport data, not to create web pages like HTML.
XML tags are not predefined, but HTML tags are.
XML can be extended (you can add new tags). You can not add new tags to HTML.

For more information on XML see https://www.w3schools.com/xml/default.asp.

Here is a sample of an XML document:

<person>
  <name>Chuck</name>
  <phone type="intl">
    +1 734 303 4456
  </phone>
  <email hide="yes" />
</person>

Each pair of opening (e.g., <person>) and closing tags (e.g., <\person>) represents a element or node with the same name as the tag (e.g., person). Each element can have some text, some attributes (e.g., hide), and other nested elements. If an XML element is empty (i.e., has no content), then it may be depicted by a self-closing tag (e.g., <email />).

csp-10-2-1: In XML, a pair of opening and closing tags (<> and <\>) represent what? Select all that apply.

element
A pair of tags in XML can represent an element.
string
A pair of tags in XML does not represent a string.
node
A pair of tags in XML can represent a node.
method
A pair of tags in XML does not represent methods.

Often it is helpful to think of an XML document as a tree structure where there is a top/root element (here: person), and other tags (e.g., phone) are drawn as children of their parent elements.

csp-10-2-2: What are the sibling tags of the email tag?

person
The person tag is the parent tag of the email tag.
name
The name tag is a sibling of the email tag.
phone
The phone tag is a sibling of the email tag.
hide
The hide is an attribute name of the email tag.

csp-10-2-3: Click on all of the self-closing tags in the XML below.The self-closing tags look like

<person>
  <name>Chuck</name>
  <phone type="intl">
    +1 734 303 4456
  </phone>
  <email hide="yes" />
</person>

csp-10-2-4: Click on all of the text in the XML tags below.The text is between the start tag and end tag

<food>
    <name>French Toast</name>
    <price>$4.50</price>
    <description>
    Thick slices made from our homemade sourdough bread
    </description>
    <calories>600</calories>
</food>

csp-10-2-5: Click on all of the attribute names in the XML below.Attributes look like name="value" and are defined in the open tags.

<person>
  <name>Chuck</name>
  <phone type="intl">
    +1 734 303 4456
  </phone>
  <email hide="yes" />
</person>

15.1.1. Properly Formatted XML¶

Solve the next couple of problems and think about what are the rules for properly formatted XML.

Put the blocks into order to define just the body of simple XML document that defines a note. A note has a date, subject, and a body in that order. Indent the blocks to show the structure (parent and child).

        <note>
---
    <date>05/16/2022</date>
---
    <subject>After work</subject>
---
    <subject>After work</Subject> #paired
---
    <body>Pick up milk.</body>
---
    </body>Pick up milk.<body> #paired
---
</note>
---
<note\> #paired

Put the blocks into order to define just the body of simple XML document that stores information for a message: to, from, time, subject, and body in that order. Indent the blocks to show the structure (parent and child).

        <message>
---
    <to>Jamal</to>
---
    <To>Jamal</to> #paired
---
    <from>Ali</from>
---
    <time region="EST">09:00:03</time>
---
    <time region=EST>09:00:03</time> #paired
---
    <subject>Meeting today?</subject>
---
    <subject>Meeting today? #paired
---
    <body>Meet today at 2:00pm?</body>
---
</message>

csp-10-2-8: Select all of the following that are true about XML.

There must be a root tag
Correct! There must be a root tag.
The case of tags doesn't matter
Incorrect. Case matters.
All elements must be closed
Correct! All elements must be closed.
Attribute values must be in quotes
Correct! Attribute values must be in quotes.

csp-10-2-9: Click on all of the end tags in the XML below.The end tags look like and have a corresponding start tag

<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>
</bookstore>

csp-10-2-10: Select the child tag of the bookstore tag.

title
The title tag is a grandchild of the bookstore tag. It is the child of the book tag.
author
The author tag is a grandchild of the bookstore tag. It is the child of the book tag.
year
The year tag is a grandchild of the bookstore tag. It is the child of the book tag.
book
Correct! The book tag is a child tag of the bookstore tag.

csp-10-2-11: Select all of the attribute values in the example XML for a bookstore.

category
No, category is the attribute name.
children
Correct, "children" is a value of the category attribute.
lang
No, lang is the attribute name.
en
Correct, "en" is a value for the lang attribute.

csp-10-2-12: Select all of the following that are true.

An element in XML that is empty (does not have content) can use self-closing tags.
Correct! An element in XML that is empty (does not have content) can use self-closing tags.
Nodes in XML can have parent and children nodes.
Correct! Nodes in XML can have parent and children nodes.
XML has predefined (standard) tags.
Incorrect. HTML has predefined (standard) tags but XML does not.
XML has opening and closing tags like HTML.
Correct! XML does have opening and closing tags like HTML.
XML is the standard language for describing web pages.
Incorrect. HTML is the standard language for describing web pages. XML is used to describe data.

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15.1. eXtensible Markup Language - XML¶

15.1.1. Properly Formatted XML¶