CSCI 2910 Client/Server-Side Programming

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CSCI 2910 Client/Server-Side Programming

• Topic Review XHTML and Forms

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Difference Between HTML and XHTML

• The purpose of HTML tags is to turn on and off
  formatting. Because of this, it isn't vital to
  observe rules such as nesting. For example, in
  HTML, the following code is okay
• ltpgtThis paragraph would ltigtnot be
• ltbgtlegallt/igt in XHTML.lt/pgtlt/bgt

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Difference Between HTML XHTML (continued)

• XHTML is an application of HTML that follows the
  rules of XML
• The purpose of XML tags is to contain data. If
  the following document were not properly nested,
  there would trouble trying to identify the data.

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XML Example

• ltclassroomgt
• ltteachergt
• ltnamegtDave Tarnofflt/namegt
• ltuseridgttarnofflt/useridgt
• lt/teachergt
• ltstudentgt
• ltnamegtAbby Betsy Catcherlt/namegt
• ltuseridgtzabc123lt/useridgt
• lt/studentgt
• ltstudentgt
• ltnamegtDavid Ebenezer Fletcherlt/namegt
• ltuseridgtzdef456lt/useridgt
• lt/studentgt
• ltstudentgt
• ltnamegtGeorge Harris Izodlt/namegt
• ltuseridgtzghi789lt/useridgt
• lt/studentgt
• lt/classroomgt

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Benefits of XHTML over HTML

• Easy to introduce new elements. (HTML typically
  only added new elements when IE/Netscape
  competition resulted in a new tag.) XHTML can be
  extended beyond predefined elements.
• More rigorous syntax makes for simpler browser
  code which is good for products such as cell
  phones.
• Better portability across different platforms.

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Differences between HTML XHTML

• Documents must be well formed
• Must have opening and closing tags for container
  tags
• New format for in-line tags
• Must be properly nested
• Element and attribute names must be in lower case
• Attribute values must always be in quotations
• Attribute minimization is not allowed, e.g.,
  NORESIZE must be noresize"noresize"
• Identify elements using both name and id
  attributes, e.g., ltinput type"text"
  name"userid" id"userid"gt

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Template for XHTML document

• lt?xml version"1.0" encoding"ISO-8859-1"?gt
• lt!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
  Strict//EN"
• "http//www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
  "gt
• lthtml xmlns"http//www.w3.org/1999/xhtml"
  xmllang"en" lang"en"gt
• ltheadgt
• lttitlegtSimple XHTML Documentlt/titlegt
• lt/headgt
• ltbodygt
• lth1gtHello, World!lt/h1gt
• lt/bodygt
• lt/htmlgt

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XML Declaration

• lt?xml version"1.0" encoding"ISO-8859-1"?gt
• The XML declaration defines the XML version and
  the character encoding that should be used to
  interpret the document.
• Computers store all information as 1's and 0's.
  There are different ways to represent characters
  using these 1's and 0's. The character encoding
  used by a document is the method to use when
  converting the 1's and 0's into characters.

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DOCTYPE Tag

• lt!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
  Strict//EN"
• "http//www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd
  "gt
• The W3C has defined a document type definition
  (DTD) to be, "...a collection of declarations
  that, as a collection, defines the legal
  structure, elements, and attributes that are
  available for use in a document that complies to
  the DTD."
• The DOCTYPE tag identifies which DTD the browser
  is supposed to use when displaying the XHTML
  document.

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Three DTD Types

• Strict DTD Adheres exactly to XHTML standard.
• Transitional DTD Uses HTML rather than CSS to
  format page. Allows use of deprecated elements.
  Allows for widest audience.
• Frameset DTD Used when document is partitioned
  into 2 or more frames.

lt!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Strict//EN "http//www.w3.org/TR/xhtml1/DTD/xhtml
1-strict.dtd"gt
lt!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Transitional//EN "http//www.w3.org/TR/xhtml1/DTD
/xhtml1-transitional.dtd"gt
lt!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Frameset//EN "http//www.w3.org/TR/xhtml1/DTD/xht
ml1-frameset.dtd"gt
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XML Namespace and Language

• lthtml xmlns"http//www.w3.org/1999/xhtml"
  xmllang"en" lang"en"gt
• The W3C has defined an XML namespace as, "a
  collection of names, identified by a URI (uniform
  resource identifier) reference, which is used in
  XML documents as element types and attribute
  names."
• The html tag is used to define the language for
  the XHTML document (lang"en") and for the XML
  used (xmllang"en").