XML Documents 5 May 2016 OSU CSE 1 e X tensible M arkup L anguage - - PowerPoint PPT Presentation

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XML Documents 5 May 2016 OSU CSE 1 e X tensible M arkup L anguage A textual document format used all over the web is XML Used to represent hierarchically organized data for ease of use both by humans and computers Had its

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XML Documents

5 May 2016 OSU CSE 1

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eXtensible Markup Language

A textual document format used all over

the web is XML

– Used to represent hierarchically organized data for “ease of use” both by humans and computers – Had its origins in SGML (Standard Generalized Markup Language) from the 1980s – Became a standard in the late 1990s

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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An XML declaration is the first line of well- formed XML file.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is not part of the actual document/file!

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is an author element.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is a start tag for an author element.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is an end tag for that author element.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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The content for this author element is everything between its start and end tags.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author></author> <title> Java for Everyone: Late Objects </title> ... </book>

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If the author element had no content, then you might find this, or…

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author /> <title> Java for Everyone: Late Objects </title> ... </book>

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… or you might find a single self-closing tag like this.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is a title element.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is a book element.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is the name of an attribute

f the book

element.

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Example XML Document/File

<?xml version="1.0" encoding="UTF-8"?> <book printISBN="978-1-118-06331-6" webISBN="1-118063-31-7" pubDate="Dec 20 2011"> <author>Cay Horstmann</author> <title> Java for Everyone: Late Objects </title> ... </book>

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This is the value

f the

printISBN attribute.

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Recursive Structure

An XML document (without the XML

declaration in the first line) is made up of:

– A top-level element – A string of zero or more child elements of the top-level element, each of which is exactly like the top-level element of an XML document

Notice the similarity to a tree: the structure
f an XML document is also recursive
Information it represents is hierarchical

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Can You Find All The Errors?

<?xml version="1.0" encoding="UTF-8"?> <pony> <unicorn mark="three lozenges"> <color>cyan</unicorn> </color> <unicorn>Twilight<color>cyan</color>Sparkle</unicorn> <unicorn mark="dolphins" version="G4" /> </pony> <dragon> <youth>Spike </dragon>

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Resources

Big Java, Section 23.1 (but not the rest of

Chapter 23)

– https://library.ohio-state.edu/record=b8540788~S7

Wikipedia: XML

– http://en.wikipedia.org/wiki/XML

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