HTML, XML, PDF

1
HTML, XML, PDF

• Pros and Cons

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HTML Pros

• Simplicity and Open standard
• HTML is easy to learn because it is very simple.
  There are only a couple dozen tags, but less than
  half of them are used in most situations.
• HTML browsers are cheap or free, and very
  powerful with a combination of third-party
  add-ins and server-side content support
• HTML document browser interfaces are easy to
  build into existing products because of the
  simplicity of HTML.
• It has become very evident to users that the
  hypertext link really does work across systems
  that are otherwise unrelated. Any page can link
  to any other publicly accessible page simply by
  entering the address.
• There are some specialized structures in HTML,
  but they are mostly used to effect a certain
  formatting look.

3
HTML Cons

• HTML is a very weak formatting tool that lacks
  even the most fundamental page-oriented
  formatting capabilities, like hanging indents,
  white-space control, justification, kerning, and
  hyphenation - lead to highly variable coding for
  even simple designs
• HTML provides linking capabilities, but the
  linking is rudimentary it is only a one-to-one
  link, and requires an anchor on the target end in
  order to access anything within the document.
• Issue of stability and versioning.
• Browser manufacturers have created non-standard
  extensions to the "standard" HTML tags, like the
  "blink" and "center" tags - lead to viewing
  problems

4
HTML more cons

• One tag set for all - not extensible
• Limited, predefined data structures
• No formal validation
• Trades power for ease of use
• Good for simple applications only
• Handcrafted - links, navigation, indexing
• Concentrates on form, not substance

5
PDF Pros

• PDF provides electronic pages with impressive
  page fidelity. Type, graphics, and color are all
  reproduced as they are on paper.
• Solves file sharing problem between platforms
• Hot links and other electronic object types, like
  movies and sounds, can be added to a PDF file.
• New features are being added constantly by Adobe
• Rights management tools and security features
  build-in

6
PDF Pros

• PDF files are cheap to create, and are used by
  many companies to deliver page-formatted
  information without the high cost of postage.
• Since the end user gets something that looks very
  much like paper, training costs are low

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PDF Cons

• Proprietary and not open to outside development
• Large file size and long to download
• PDF files are not nearly as flexible as other
  electronic formats because the main goal is to
  recreate a paper page, and not to provide a way
  of delivering intelligent document structure to a
  user
• There is limited support for searching, although
  Adobe has products that can index many different
  PDF files for cross-document searching and
  navigating

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What about SGML?

• Hard to learn
• Costly to implement
• Not web friendly in full form
• Style support poor
• Hard to get a fast start
• Tooling up very expensive
• Good linking (HyTime), hard to implement

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XML

• A structured markup meta-language
• A sub-set of SGML designed for the Web
• Designed to work with companion standards
• for linking
• for styling
• Web friendly the next step in Web evolution
• Overcomes limitations of HTML and CSS
• Enabler for new Web applications

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XML and the Web

• is Extensible
• is Quicker, easier and cheaper to implement
• preserves the structure of data
• supports complex nesting of structures
• has strong linking types - URLs and more
• provides comprehensive style features
• CSS
• XSL

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XML and theWeb

• Is a standard approved by the W3C
• XLink, XPointer, XSL also standards
• Incorporates best features of DSSSL, CSS,
• and HyTime TEI
• Uses UNICODE for universality
• Works with Java and JavaScript

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XML Application Models
XML Application

• Does your project intend to use XML for data
  storage or for data exchange or both?
• What types or classes of data are to be stored or
  shared using XML?
• Do standard XML DTDs or XML Schemas for the
  description of this data exist?
• How will you create your XML documents? Will they
  be authored with a suitable editor or generated
  by software tools?

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XML Questions to consider

• Are you exchanging data or metadata through
  specific agreements with a defined number of
  partners?
• Are you supplying metadata to specific services?
  Do those services specify requirements for the
  syntax, structure and semantics of the data they
  accept? Do those services specify conformance to
  XML DTDs or XML Schemas which they provide?
• Or are you intending to make data or metadata
  available in a more "open" environment, with the
  expectation that it may be used by a potentially
  unlimited number of services?

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XML

• With whom do you need to share your data or
  metadata?
• Is it appropriate to make that metadata available
  through OAI?

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XML example

• PubMed DTD
• http//www.ncbi.nlm.nih.gov80/entrez/query/stati
  c/publisher.htm