Office Automation & Intranets

Clarke, R. J (2001) L909-05: 1

Office Automation & Intranets

BUSS 909

Lecture 5From Storage to

Interchange: Standard Generalized Markup

Language (SGML)

Clarke, R. J (2001) L909-05: 2

Notices 1

Assignment 1 is due next weekAssignment 2 will be available from

the Intranet next week. As with the current assignment, there are some administrative requirements that must be fulfilled by all students- described next lecture

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Notices (2)

to accommodate the new T1 tutorial for this subject, my Consultation Time C1 which was 14:30-16:30 is now 13:30-15:30 40.242 remaining in effect until the end of session

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Agenda

Types of MarkupStylesheets & Markup (wrt HTML)SGML StandardSGML ExampleSGML BenefitsAdopting SGML

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Types of Markup

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Types of Markup

the following slides show an extract from a Vincent motorcycle repair manual to illustrate the types of markup which can be used on a document

but just in case you don’t know what a Vincent motorbike looks like, here is a picture of a 1994 rebuild of the 1959 classic...

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1994 Vincent Motorcycle

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Types of MarkupProcedural Markup

the following two slides shows an extract from a Vincent motorcycle repair manual showing the procedural markup

this kind of markup tells a workprocessor or other related system how to render (or display) the page

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Procedural Markup

Centre; 10pt Times-Roman

Down 10pt; centre;12pt. Helvetica Bold

Down 15pt.; first line indent 0.3 inch; 12-pt. Times Roman

Down 22pt.; centre; 10-pt. Helvetica Medium

Down 5pt.; centre; 12-pt Helvetica Bold

Down 10pt.; 12-pt Times Roman run-in bold

(Source: Nicholson Brothers Motorcycles Ltd. 1994)

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Procedural Markup (continued)

Down 22pt.; centre; 10-pt. Helvetica Medium

Down 5pt; centre;12pt. Helvetica Bold

Down 15pt.; 12-pt. Times Roman

Down 10-pt.; indent 0.32 inch first line indent 0.325 inch right align 0.2 inch; tab left alighed 0.325 inch 12-pt. Times Roman


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Types of MarkupDescriptive Markup

the following two slides shows an extract from a Vincent motorcycle repair manual showing the descriptive markupthe descriptive markup used in this example

identifies the structure of the documentthis type of markup could be used to describe

the data or information structure of the document

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Descriptive Markup

chapnum (Chapter number)

title

titlepara

sectnum(Section Number)

title

labitem (Label list item)


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Descriptive Markup (continued)

sectnum (Section number)

title

sectnum (Section number)

listitem (List item)


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Stylesheets and MarkupEmphasising HTML

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Stylesheets and Markup

for any real document based system, we need to:design the content of the document-

descriptive markup- independent of its lookdesign the look of the document- procedural

markup- independent of its contentwe need to relate them together because

content must be displayed- this is done by using stylesheets

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Stylesheets and Markup

Focus: Information System

Function: How to display or render the elements of a document

Stylesheet

Focus: Assist users/readers in interpreting the meanings of a document by means of a consistent visual look

Function: providing a consistent look and feel- procedural issue- to meaningful elements of a document- descriptive issue.

Focus: Human Users

Function: What is the meaning of an element in a document, what purpose does it serve for the organisation

Descriptive MarkupPrescriptive Markup

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Stylesheets and MarkupHyper Text Markup Language

In principle, HTML as a standard attempts to provide structural meaning to page content- the purpose of tagswhat is enclosed between <P>…</P> is

interpreted as a paragraph

unfortunately, structural markup is only a limited form of descriptive markup

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Stylesheets and MarkupHTML 4.0 Specification (1)

unfortunately, most web page authors concentrate only on the look of the page (by heavily using the procedural markup oriented tags)

the introduction of the HTML 4.0 specification attempted to distance the content of web pages from formatting issues

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Stylesheets and MarkupHTML 4.0 Specification (2)

this standard encouraged reduction in the use of formatting (procedural) markup like <FONT>…</FONT> and <H1>...</H1>, <H2>...</H2> etc. tagsformatting was assigned to a separate

standardization effort related to content style- Cascading Style Sheet (CSS)

provided the means to pass the decision as to how a paragraph looks to a style definition

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Stylesheets and MarkupLink between Stylesheet and Content

In HTML, the link between a style sheet and the content it influences is either:tag name of the HTML element that

holds the content or,an identifier associated with the element

by way of an attribute (eg. ID or a CLASS attribute)

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Stylesheets and MarkupCascading Style Sheets

Cascading Style Sheets (CSS) allows authors to define style rules to each HTML element and these rules may apply to either:single elementsa related group of elements, or toall elements of a particular type (such

as all P elements)

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Stylesheets and MarkupStyle Rules in CSS (1)

style rules influence the rendering of elementscolour, alignment, border, margins, and

padding between borders and contentcan also control special items eg.

whether Ordered List (OL) elements use bullet symbols, letters or roman numerals

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Stylesheets and MarkupStyle Rules in CSS (2)

every style rules have two parts:one or more elements or groups of elements

that have style sheets defined for themone or more style sheet attributes that apply

to the elements

then need to relate or bind stylesheets to HTML elements (eg. to all P elements)- several possible approaches

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Stylesheets and MarkupApproaches of Binding

two major approaches to binding stylesheets to HTML elementsin-document stylesimporting external stylesheets

the choice of approach depends on:the size and complexity of the web sitethe size of the development team user community diversity and expertise

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Stylesheets and MarkupIn-Document Style Binding (1)

:

<BODY>

<H1 STYLE= “color:red; text transform:capitalize”>Some heading</H1>

<P STYLE=“color:blue”>Some paragraph text</P>

:

<BODY>

One form of In-Document Style Binding associates a style declaration to an HTML element using the elements’ STYLE attribute

Usage: convenient if style rules are

few and simple difficult to maintain in large

sites as changes must be made throughout the HTML file

Note: almost every HTML element can have a STYLE attributeassociated with it

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Stylesheets and MarkupIn-Document Style Binding (2)

Another form of In-Document Style Binding is to define and group together all style rules between <STYLE>… </STYLE> tags

Usage: better option when trying to

maintain a moderately complex page

promotes modular design and implementation of page

<HTML>

<HEAD>

<STYLE TYPE =“text/css”>



</STYLE>

:

:

:

<BODY>

<H1>Some heading</H1>

<P>Some paragraph text</P>

</BODY>

</HTML>

Note: style rules are enclosed in HTML comments to prevent older browsers from trying to render them

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Stylesheets and MarkupBinding using External Stylesheets

Define and apply an external style sheet file to one or more HTML files

the external style sheet file (above, left) contains only rules no HTML tags

Usage: promotes a consistent look

similar to work processor style sheets

separates the documents’ structure and look

Note: these style rules are stored in the file called mystyles.css

H1 {color:red; text-transform:capitalize}P {color:blue}

<HTML><HEAD><LINK REL=STYLESHEET TYPE=“text/css” HREF=“mystyles.css”>:</HEAD><BODY><H1>Some heading</H1><P>Some paragraph text</P></BODY></HTML>

Note: rules are applied to HTML file on the fly

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Stylesheets and MarkupDifficulties with HTML (1)

While the CSS Level 1 is consistent across major browsers, it doesn’t provide exact positioning of elements on a page

the CSS Level 2 standard supports exact positioning but there are differences in implementation across major browsers

CSS Level 2 has many advantages but in order to preserve the same look developers may be forced to use Level 1- or undertake a major development task!

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there is a much more serious problem:the stylesheet and descriptive markup capabilities

of HTML 4.0 and DHTML (HTML 5.0), were not built into it from the start

describing the structure is not the same thing as descriptive markup

users cannot create there own tags based on meanings (semantics)- for example no tags for PART NUMBER or COURSE- HTML not extensible

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on the Internet simplicity wins over efficiency- the Web has grown because its core standards are simple:proof of this is that HTML is itself written

using another standard for describing documents- this standard is called SGML

SGML has also been used to develop a standard likely to replacement HTML on the web- XML described in Lecture 13

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SGML Standard

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SGML Standard

internationally recognised standard (ISO 8879) for describing and enforcing structure and properties onto data in computer base information systems, including semi-structured datacompletely descriptive markup system for

document contentopen environment for the interchange of a

portable generic format between platforms

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SGML StandardFeatures (1)

major features: syntax for text processing stylesheets extensible document description language meta-language for defining document types

text media support: text is coded according to its meaning- can be

used in way not originally envisioned tagging language database language for text

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media processing applications: foundation for multimedia and hypertext- HyTime

(an ISO standard) is an SGML application that knows about multimedia, time-based events, synchronisation

general computational features: handles logical structures (conditional

documents) notation for structures (eg. hierarchies):

sequences, repetitions and selections

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other aspects:general file linking and addressing

schemeopen document representation

language for any system architecturesupports open inter-communication

regardless of hardware platforms and software applications

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SGML StandardInstances & Document Type Definition

An SGML document is text only, but has the following structure:an document instance containing the

dataa document type definition (DTD)

defining what data elements can be in the document, and how these data elements relate to each other

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SGML Standard Document Instances

document instances contain data and markup (called tags):both data and tags are in ASCII format- read

by any applicationtags are distinguishable from data: tags

always have pairs of <> bracketssome system specific data can be inserted

into the instance using special tags- removes the need for control codes etc

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SGML StandardDocument Type Definition (1)

can be stored at the beginning of the document or externally in a separate file (generally the latter)

consist of all the formal definition of the elements, structures, and rules for marking up a given type of SGML document

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SGML Standard Document Type Definitions (2)

comprise rules and relationships that define how the different elements within a document relate to each other:specify the order in which headings occurwhich elements are allowed under each

headingthe order and frequency with which elements

should appear

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SGML Standard Document Type Definitions (3)

specifies the permitted document elements eg. ‘Chapter’, ‘Heading’, ‘Definition-entry’,

‘Defined-work’, ‘Definition’ and ‘See-also’

each element typically has a content model stating its required or permitted contents. eg. the content model for ‘Definition-entry’ would

state that it must have only one ‘Defined-word’ and ‘Definition’

‘Defined-word’ and ‘Definition’ must also be described by content models

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Document Type DefinitionExtract of an SGML Memo DTD

<! -- DTD for simple office memoranda --->

<! --

<! ELEMENT MEMO -- ((TO & FROM), BODY, CLOSE?) >

<! ELEMENT TO -0 (#PCDATA) >

<! ELEMENT FROM -0 (#PCDATA) >

<! ELEMENT BODY -0 (P) * >

:

:

<! ATTLIST MEMO STATUS (CONFID | PUBLIC) PUBLIC >

:

:

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SGML Processing Systems (1)

read a document instance, and refers to a DTD to find out how to process itaspects of the document instance such as

format of the page, fonts spacing etc. are not defined in SGML (a distinction between PostScript for example and SGML)

must exist in heterogeneous environments where not all documents are in SGML

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SGML Data SGML DTD

ApplicationLibrary

Application Output

SGML Parser

SGML Processing System

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TagApplication

SGMLApplications

BitmapEdit/Convert

Non-SGMLEditing System

SGML Edit/Convert

New Data

New Data

Legacy Documents

GraphicsFiles

SGMLFiles

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DSSSL

Document Style Semantics and Specification Language (DSSSL)is the ISO international standard (ISO

DIS 10179) which addresses the need for detailed, typographically sophisticated, specification of layout and composition

independent of particular formatting systems or processes

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SGML Example

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SGML ExampleInformational Content Markup

the following two slides shows an extract from a Vincent motorcycle repair manual

show the informational content markup using SGML

note that SGML tags are usually shown in the form <…> followed by </..>

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Information Markup


CHAPTER (BIKETYPE=”Vincent”)

INTRO Although the design of the Vincent differs substantially from conventional motorcycles,operating procedure and maintenance requirements are comparatively similar. /INTRO

LUBE

SUPPLIES

ITEM Grades of Motor Oil /ITEM

DETAIL CROSSREF [TARGET=”PG142”] /CROSSREF /DETAIL

ITEM Motor Lubrication /ITEM

DETAIL Oil supply is contained in tank which forms the

LOCATION top frame member. /LOCATION Motor oil tank capacity is

CAPACITY [UNITS=”QUARTS”] 3. /CAPACITY /DETAIL

ITEM Motor Oil Filter /ITEM

DETAIL A fabric filter is located at

LOCATION front of crankcase below the magneto. /LOCATION /DETAIL

ITEM Gearbox Oil /ITEM

DETAIL Oil capacity is

CAPACITY [UNITS=”PINTS”] 3. /CAPACITY /DETAIL

/SUPPLIES

/LUBE

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Information Markup (continued)


TIMING

NOTE Due to the Vincent’s uneven firing interval, timing should be checked on both cylinders./NOTE

METHOD

STEP [ ] PARA Set breaker points to POINTGAP [UNITS=”INCHES”] .012/POINTGAP fully open with a TOOL screwdriver. /TOOL /PARA/STEP

STEP [ ] PARA Using TOOL degree plate, /TOOL set the flywheel so that thedegree wheel reads at KEYVALUE [UNITS=”DEGREES”] 37-38 /KEYVALUEbefore TDC. /PARA /STEP

STEP [ ] PARA With a piece of wood, block the automatic advance in the fully advancedposition. /PARA /STEP

STEP [ ] PARA Using a TOOL hex key, /TOOL revolve magneto via the breakerpoint assembly until points just commence to separate. /PARA /STEP

STEP [ ] PARA Fix the gear to magneto shaft, by placing TOOL box wrench /TOOLover nut and giving sharp rap with TOOL hammer. /TOOL /PARA /STEP

/METHOD

/TIMING

/CHAPTER

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SGML Benefits

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SGML Benefits

DTD structure forces the user to focus on document content not format

SGML helps the authors by:suggesting the correct structure of

different document typesenforces the correct structure: if an author

attempted to put in non-standard material, the application would refuse to accept it

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SGML Benefits

Data Managementcommon data repository for the

enterprisestandardised formatting for informationminimise data duplicationcontrol/check data qualitymaximises the benefit of data entry and

authoring

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SGML Benefits

facilitates data exchange within an enterprise (Intranets)prevents islands of information forming

within the organisation (that is information trapped within specific functional areas)

prevents an ‘isolationist mentality’ forming within specific functional areas (‘marketing’ data rather than organisational asset)

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SGML Benefits

facilitiates data exchange between an organisation and business partners (Extranets; EDI) promotes participation between partnersreduces costs, improves performancestreamlines operations and maangement

practices, reduces ‘bottlenecks’

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SGML Benefits

Video Case Studies about EDINote that SGML could well have been

an enabling technology for EDI in these CASE Studies

take notes on how these EDI systems were negotiated- what are the Tactical Strategic and Operation implications suggested in these cases

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Adopting SGML

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Adopting SGML

Data AnalysisFeasilbility StudyStandardising Data ConceptsData Entry & Document ConversionDelivery of Data to Users