XHTML Presentation by Kevin See June 16, 2000
XML in HTML Meeting Report May 11, 1998 html html How do we “hide” new idioms from deployed software How do we introduce new idioms with distinctive display characteristics, such as MathML?
What Is XHTML? XHTML (Extensible Hypertext Markup Language) is “a reformulation of HTML 4 as an application of the Extensible Markup Language (XML)” XHTML is a family of current and future document types and modules that reproduce, subset, and extend HTML 4.
Why Would You Want to Use XHTML? Extensibility 1. Powerful machine 2. New tags / attributes 3. Lead to more complicated pages and larger programs Portability 1. Small devices – mobile devices and possibly household devices 2. Several levels of possible markup 3. Web pages can now be made simpler
Document Conformance Strictly conforming documents Must validate against proposed DTDs. Root element must be. Root element must designate the XHTML namespace using the xmlns attribute. (see next slides for details) There must be a DOCTYPE declaration in the document prior to the root element.
Document Conformance- Using XHTML With Other Namespaces A Math Example The following is MathML markup: 3 x
Document Conformance- Using XHTML With Other Namespaces <book xmlns='urn:loc.gov:books' xmlns:isbn='urn:ISBN: ' xml:lang="en" lang="en"> Cheaper by the Dozen This is also available online.
User Agent Conformance Consistent with XML 2. Consistent with facilities definition 3. Recognize attributes of type ID 4. Unrecognized Items 5. Space, Tab, Carriage Return, Line Feed are considered as white space.
DTDs – Document Type Definitions XHTML 1.0 specifies three XML document types that correspond to the three HTML 4.0 DTDs: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd"> XHTML 1.0 Strict <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "DTD/xhtml1-transitional.dtd"> XHTML 1.0 Transitional <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "DTD/xhtml1-frameset.dtd"> XHTML 1.0 Frameset
Differences With HTML 4 Document must be well-formed Tag and attribute names must be written in lower-case (see XHTML Case Poll) XHTML Case Poll For non-empty elements, end tags are required Empty elements must be terminated (e.g. ) Attribute values must always be quoted (e.g. Attribute value pairs cannot be minimized (e.g. ) “name” attribute is formally deprecated (to be removed later), use “id” attribute instead
Differences With HTML 4 and elements are declared as having #PCDATA content. e.g. <![CDATA[ document.write(" Hello World! "); ]]>
Differences With HTML 4 – SGML Exclusions a cannot contain other a elements. pre cannot contain the img, object, big, small, sub, or sup elements. button cannot contain the input, select, textarea, label, button, form, fieldset, iframe or isindex elements. label cannot contain other label elements. form cannot contain other form elements.
Compatibility Issues With Existing User Agent Although there is no requirement for XHTML 1.0 documents to be compatible with existing user agents, in practice this is easy to accomplish. Appendix C summarizes design guidelines for authors who wish their XHTML documents to render on existing HTML user agents.
XHTML Document Structure An XHTML document consists of three main parts: The DOCTYPE, The Head, and The Body Here is a minimal XHTML document 1: 2: 3: 4: Minimal document 5: 6: 7: 8: validate 9: 10: 11:
Future Directions Modularizing XHTML (hand held device) – The process of modularization breaks up XHTML up into a series of smaller element sets. These elements can then be recombined to meet the needs of different communities. Modularizing XHTML
Future Directions Document Profiles A document profile specifies the syntax and semantics of a set of documents. Conformance to a document profile provides a basis for interoperability guarantees. The document profile specifies the facilities required to process documents of that type.
Conclusion Example of site written in XHTML - Brian White & AssociatesBrian White & Associates XHTML 1.0 Combines the Familiarity of HTML with the Power of XML XHTML 1.0 Provides a Foundation for Device-Independent Web Access XHTML 1.0 allows authors to create Web documents that work with current HTML browsers and that may be processed by XML- enabled software as well. With XHTML, we are well-prepared to move into the 21st century web.
Interesting URLs HTML conversion tool – Tidy HTML conversion tool – Tidy HTML Writers Guild – world largest international organization of web authors (over 110,000 members, over 150 countries) HTML Writers Guild – world largest international organization of web authors (over 110,000 members, over 150 countries) W3C HTML validation Service W3C HTML validation Service HTML Validator – Commercial Product HTML Validator – Commercial Product FOP – formatter that produces PDF from XSL formatting objects FOP – formatter that produces PDF from XSL formatting objects
Interesting URLs W3C's Amaya Browser - The latest release includes the support of HTML 4.0 and XHTML W3C's Amaya Browser - The latest release includes the support of HTML 4.0 and XHTML Slide set on XHTML -This is a recent slide set for XHTML first presented at the W3LA event in Stockholm on 24th March Slide set on XHTML -This is a recent slide set for XHTML first presented at the W3LA event in Stockholm on 24th March 1999.