Download ECT 360 Introduction to the Class

ECT 360
Introduction to the
Class
Prof. Robin Burke
ECT 360
Winter 2004
Outline
Introductions
 Course and Syllabus
 XML
 XHTML
 Homework #1

Introductions

Student information sheet
Administrativa

Contacting me
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Questions


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CS&T 453
x 25910
[email protected]
Try the course discussion forum
Automatically mailed to all students
I will also post announcements here
Course web site

http://josquin.cs.depaul.edu/~rburke/courses/
w04/ect360/
About Me
2nd year at CTI
 PhD in AI, 1993
 Research

AI applications in E-Commerce
 "smart catalogs"

Taught web development since 1996
 What I hope to get out of teaching this
class

Course

Introduction to XML


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concentrate on XML's uses for the web
many other uses!
Three parts


XML itself
Display of XML = XML style
• CSS / XSLT

XML applications
• XML languages for specific tasks
Course cont'd
Six homework assignments
 Midterm 2/2
 Final project
 Allocation

Homework – 40%
 Midterm – 30%
 Final project – 30%

Grading

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Three Components
Knowledge
 Does the work display correct technical knowledge?
Reasoning
 Does the work indicate good problem-solving skills?
Communication
 Written work: Is the answer well-written English?
 Code: Does the answer display good coding /
documentation style
Grading, cont'd
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A = Excellent work
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B = Very good work

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
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Complete knowledge of the subject matter
No major errors of reasoning in problem solutions
Competent written answers
Readable coding style
C = Average work
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
Thorough knowledge of the subject matter
Well-considered and creative solutions
Well-written answers
Employment of impeccable coding style
Some gaps in knowledge of subject matter
Some errors or omissions in problem solving
Written answers may contain grammatical and other errors
Coding may be stylistically awkward
D = Below average work
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Substantial gaps in knowledge of subject matter.
Problem solving incomplete or incorrect
Poor English in written answers
Ineffective coding style
Resources

Text


Carey, P. New Perspectives on XML
(Comprehensive). Thomson Learning
Tools

XML Spy
• 4.3 included with book

XML Spy Enterprise 2004
• available in 6th floor lab
Discussion enhancement

Card distribution
XML
eXtensible Markup Language
 Misnomer

Not a language
 Technology for creating languages

XML



Looks a little bit like HTML
But with a wide variety of tag names
Reason
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HTML and XML have a common ancestor
• SGML


Developed for entry and management of
very large documents
Why do we need XML?
Web publishing with HTML
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Develop content
Determine how content should be displayed
on pages
Encode content in HTML
Content available to users
Problem

what happens when content changes
• design decisions must be rethought

what happens when design changes
• HTML must be rewritten

designer and author must work closely
Web publishing with XML
Develop XML application for content
 Develop content
 Content encoded in XML
 Design pages
 Write stylesheet to render pages in
HTML
 Content available to users

Benefits
If design changes, only stylesheet is
affected
 Different pages / displays can be
generated from the same content
 Designer and author need not interact

Big picture
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Modularity is a good thing
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
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decoupling of data's structure from its use in
a particular application
lowers effort of repurposing data
Modularity requires standards

non-application specific data representation
• not in the interest of any application vendor

XML is the language in which such
standards can be expressed
XML applications

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Purpose-specific languages that conform to
the XML standard
Many are standardized
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XHTML, SVG, RDF, SOAP, SMIL, WML, etc.
In-house languages easy to develop
XML is becoming the default choice for data
storage format

MS Office 2003
Example: Course
<?XML version="1.0"?>
<!DOCTYPE course SYSTEM "course.dtd">
<course>
<name>Introduction to XML</name>
<number>ECT 360</number>
<section>
<section-number>801</section-number>
<instructor>
<instructor-name>Robin Burke</instructor-name>
<email address="[email protected]" />
</instructor>
<schedule>
<meeting>
<day>Monday</day><time>5:45 pm</time>
<duration>3:15</duration><room>Lewis 1508</room>
</meeting>
</schedule>
</section>
... see full example ...
Note

Structure determined by needs of
application
Any number of sections
 Any number of meetings


Other design choices could be made

separate components of course
number
The rules of XML
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Documents consist of elements, attributes and content
 (and a few other things)
Elements are set off by tags in angle brackets
 start tag for element foo <foo>
 end tag for element foo </foo>
Anything in between the start tag and end tag is
element content
Attributes are additional data associated with an
element
 indicated by name/value pairs inside the start tag
• <foo bar="2">
More rules
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Comments
 enclosed by special character sequence
 <!-- -->
Document prolog
 before the first element
 contains declarations
 typically
• declare that it is xml
• declare the relevant document type

Processing instructions
 information that the XML parser doesn't use
 passed along to the application
 Special tag <?
Entities
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Special characters
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Certain characters part of the language
Need a way to indicate these
• &lt;  <
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Entities can be defined as part of a
document type


useful for inserting standard text
&copyright; might insert a standard copyright
notice
Document tree
Document is just one form of XML
 More useful for computation

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Tree representation
XML Tree
course
name
number
TEXT
"Introduction
to XML"
TEXT
"ECT 360"
sectionnumber
section
section,
etc
schedule
instructor
instructorname
email
day
meeting
time
duration
address=
"[email protected]
room
Tree

Nodes
elements
 text nodes


Attribute lists
Paths
A path traverses the tree
 XPath provide syntax for tree traversal
 Example
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
/section[2]/meeting[1]/day/
Transformation
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XML transformations change the XML
tree
adding
 deleting
 changing contents
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Well-formed vs valid
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A well-formed document is one that obeys
the syntactic rules
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it can be parsed
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<foo bar="2"><baz>thud</baz>&zap;</foo>

well-formed document
A valid document has been validated
against some standard


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what is the entity zap?
is baz a legal subelement for foo?
unknown without a definition for foo
XML Validation
Validation is the process of checking
an XML document against a standard
 Different languages for defining such
standards
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DTD – document type definition
 XML Schema
 RELAX NG
 others

Document type

The document type specifies the legal
structure of the XML document
order, contents of elements
 legal attributes and default values
 etc.

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Designing a document type means
deciding what data will be stored and
how
HTML
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HTML is not XML-compliant
XML is case-sensitive
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XML requires quotes around attributes
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HTML optional
XML requires end tags
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HTML is not
Optional in some cases for HTML
XML requires /> syntax for empty elements
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HTML does not
XHTML
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Latest HTML standard
Makes HTML XML-conformant
Different flavors

Transitional
• allows style information as part of the document
(align attribute)
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Frameset
• allows frames
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Strict
• no frames, no style attributes
• assumes use of a stylesheet for rendering
Benefits of XHTML

XML

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decouples data from application
XHTML
decouples content from style
 for web documents

Modularity = More pieces
HTML
document
Web browser
XML
data
XHTML
document
XSLT
stylesheet
CSS
stylesheet
Web browser
More pieces =
More flexibility
XML
data
XSL-FO
stylesheet
PDF
document
XML
data
XSLT
stylesheet
SVG
graphics
Converting to XHTML

No sloppiness

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tags must nest
end tags everywhere
quotes on attribute values
remove deprecated elements / attributes
• replace with style

XML-specific

/> for empty elements
• like img
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declarations
• xml
• doctype
• namespace

lowercase
Example
HTML  XHTML conversion
 Validation

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on-line validator
Assignment #1
Convert a file to XHTML
 Use the online-validator
 Due
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before class time next week
 submit to COL
