Network publishing and mark-up languages. Alpe Adria Master Course :: Medical Informatics :: Dr. J....

Network publishing and mark-up languages

Alpe Adria Master Course :: Medical Informatics :: Dr. J. Dimec: Web publishing and mark-up languages. 2

p- versus e-form

The share of documents in e-form and accessible over the network is growing fast.

There are types of documents that will “always” exist in a paper form or co-exist in both forms.

There are numerous types of documents that already function better in e-form, at least for some populations (or generations).

The e-document can replace the paper form only if it is readable without limits of time and place.


Independence of place

Document should be usable in the same way irrespective of server’s distance and user’s hardware and software for reading.

It is mainly a technological problem. We need a reader of a size and weight of a book, with screen with visual characteristics of a paper, with autonomous power supply, with wireless connection to servers with documents.

All that we already have, but not in one reasonably expensive appliance.


Independence of time

Document must have the same usability until potential readers disappear.

It is mainly an organisational problem: we need standard document formats, which will be

understood by future generations of software and hardware, and

we need consensus to obey those standards. Such standard formats are made by mark-up

languages.


History of e-publishing

At the beginning the creators of e-documents were few, mostly creators of bibliographic databases.

They independently developed formats of their e-documents and software for their use.

It was easy because e-documents were simple, ASCII files.

Things became complicated with the development of more complicated, multimedia documents.


History of e-publishing

Because of the lack of standardisation new documents were not usable by definition on every operating system and brand of computer.

Producers of e-documents were forced to develop different versions of documents and/or software for its use for all major brands of OS and computers.

It was economically unfeasible and the only exit was standardisation.

Standardisation of computers? Impossible. Standardisation of e-document formats.


Mark-up languages: introduction

Mark-up languages must make possible: the transfer of documents between different types of

computers and software for reading, simple and economical transport through networks, longevity of documents (problem of e-archiving).

Mark-up languages enable us to mark structure and/or form (appearance) of documents.


Mark-up languages: introduction

Mark-up languages are artificial languages, composed of: labels (tags) that divide document into structural

elements, tags that describe appearance of structural elements,

and syntax that defines appropriate use of tags.


Structure vs. appearance

If mark-up language defines only structure of a document, then its appearance on a screen or paper is entirely dependent on the software used for document’s representation.

In such case the structure of document is separated from definitions of fonts, colour of background, distance between lines, etc. With such attributes of documents the printing-house mark-up languages are dealing.


RTF

Very common type of e-documents are documents written with word processors, e.g. MS Word for Windows.

Structure and appearance of documents are inseparable.

The result is very limited possibility of transfer of documents between different types of computers or operating systems; even between different generations of same word processor.

More advanced is word processor, more closed system it is.


RTF

A strong need exist for transportability of word processor files.

Developers of word processors agreed upon the common transport format, which is understood by the most programmes of that kind.

This is RTF – Rich Text Format. RTF denotes only document’s appearance.


RTF: example

{\rtf1\ansi\deff20\deflang1033{\fonttbl{\f4\froman\fcharset0\fprq2 Times New Roman;}{\f5\fswiss\fcharset0\fprq2 Arial;}{\f20\fnil\fcharset0\fprq2 SLOHelvetica;}}{\colortbl;\red0\green0\blue0;\red0\green0\blue255;

... 20 to 30 lines of lines with general description of fonts and distances follow ...

\pard\plain \qr\sb40\sa40\tx357 \f20\fs20\lang2057 {\fs18 Lecture: Computer communications, Databases 2} \par \pard\plain \s18\sb40\sa40\tx357 b\f20\fs30\lang2057 {\i\fs32 Predavanje: Standardi za označevanje dokumentov \par }\pard\plain \s1\fi-360\li360\sb240\sa40\tx357 \b\f20\fs28\lang20571.\tab Reasons for standardisation of document descriptio

tags for types and colours of fonts

tags for text positioning


Postscript and PDF

Postcript (Adobe): Mark-up language for driving laser printers. Marks only document’s appearance, including

images.

PDF (Portable Document Format): Makes possible the original appearance of a

document on a web browser. Documents on screen look the same as on the paper. Simplified and upgraded variant of Postscript. Marks appearance and only partly structure (hyper-

text pointers).


SGML

SGML: Standard Generalized Mark-up Language. International standard, adopted by ISO on 1986

and upgraded several times since then. Family of standards, managing the mark-up of all

known types of e-documents. Its strength is generality, because logical

structure and appearance of a document are completely separated.

Appearance is left to software for representation of documents on screen or paper.


SGML

SGML divides e-document into three parts: Declaration, which describes the most general data about

document (Latin or Cyrillic script…) and symbols with special meaning for SGML.

Document Type Definition (DTD), which describes the possible structural elements of document, their meaning, hierarchical relationship among structural elements, and tags that mark these structural elements.

Body of a document, marked with tags.


HTML

SGML is not a real mark-up language but a recipe how to build mark-up languages for different types of documents.

HTML is such language developed for web documents.

It is relatively simple and this is the reason for extreme simplicity of web publishing.

In its original versions it mostly defines structure and only partly appearance of documents.

Author: Tim Berners-Lee (early 90’s).


HTML

The standardisation of HTML is endangered since its birth.

Big producers of web browsers, Microsoft and Netscape try to impose their own tags and functionality to beat the competition.

Documents written with some word processors for HTML can not be read on browsers made by competition.

It is safe to use simple Notepad or Netscape’s editor.

Network publishing and mark-up languages. Alpe Adria Master Course :: Medical Informatics :: Dr. J....

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