BUSS 909 Office Automation & Intranets Lecture 5 From Storage to Interchange: Standard Generalized Markup Language (SGML) Clarke, R. J (2001) L 909 -05: 1
Notices 1 n Assignment 1 is due next week n Assignment 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 studentsdescribed next lecture Clarke, R. J (2001) L 909 -05: 2
Notices (2) n to accommodate the new T 1 tutorial for this subject, my Consultation Time C 1 which was 14: 30 -16: 30 is now 13: 3015: 30 40. 242 remaining in effect until the end of session Clarke, R. J (2001) L 909 -05: 3
Agenda n Types of Markup n Stylesheets & Markup (wrt HTML) n SGML Standard n SGML Example n SGML Benefits n Adopting SGML Clarke, R. J (2001) L 909 -05: 4
Types of Markup Clarke, R. J (2001) L 909 -05: 5
Types of Markup n 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 n 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. . . Clarke, R. J (2001) L 909 -05: 6
1994 Vincent Motorcycle Clarke, R. J (2001) L 909 -05: 7
Types of Markup Procedural Markup n the following two slides shows an extract from a Vincent motorcycle repair manual showing the procedural markup n this kind of markup tells a workprocessor or other related system how to render (or display) the page Clarke, R. J (2001) L 909 -05: 8
Procedural Markup Centre; 10 pt Times-Roman Down 10 pt; centre; 12 pt. Helvetica Bold Down 15 pt. ; first line indent 0. 3 inch; 12 -pt. Times Roman Down 22 pt. ; centre; 10 -pt. Helvetica Medium Down 5 pt. ; centre; 12 -pt Helvetica Bold Down 10 pt. ; 12 -pt Times Roman run-in bold (Source: Nicholson Brothers Motorcycles Ltd. 1994) Clarke, R. J (2001) L 909 -05: 9
Procedural Markup (continued) Down 22 pt. ; centre; 10 -pt. Helvetica Medium Down 5 pt; centre; 12 pt. Helvetica Bold Down 15 pt. ; 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 (Source: Nicholson Brothers Motorcycles Ltd. 1994) Clarke, R. J (2001) L 909 -05: 10
Types of Markup Descriptive Markup n the following two slides shows an extract from a Vincent motorcycle repair manual showing the descriptive markup n the descriptive markup used in this example identifies the structure of the document n this type of markup could be used to describe the data or information structure of the document Clarke, R. J (2001) L 909 -05: 11
Descriptive Markup chapnum (Chapter number) titlepara sectnum(Section Number) title labitem (Label list item) (Source: Nicholson Brothers Motorcycles Ltd. 1994) Clarke, R. J (2001) L 909 -05: 12
Descriptive Markup (continued) sectnum (Section number) title sectnum (Section number) listitem (List item) (Source: Nicholson Brothers Motorcycles Ltd. 1994) Clarke, R. J (2001) L 909 -05: 13
Stylesheets and Markup Emphasising HTML Clarke, R. J (2001) L 909 -05: 14
Stylesheets and Markup n for any real document based system, we need to: n design the content of the documentdescriptive markup- independent of its look n design the look of the document- procedural markup- independent of its content n we need to relate them together because content must be displayed- this is done by using stylesheets Clarke, R. J (2001) L 909 -05: 15
Stylesheets and Markup 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 feelprocedural issue- to meaningful elements of a document- descriptive issue. Prescriptive Markup Descriptive Markup Focus: Information System Focus: Human Users Function: How to display or render the elements of a document Function: What is the meaning of an element in a document, what purpose does it serve for the organisation Clarke, R. J (2001) L 909 -05: 16
Stylesheets and Markup Hyper Text Markup Language n In principle, HTML as a standard attempts to provide structural meaning to page content- the purpose of tags n what is enclosed between <P>…</P> is interpreted as a paragraph n unfortunately, structural markup is only a limited form of descriptive markup Clarke, R. J (2001) L 909 -05: 17
Stylesheets and Markup HTML 4. 0 Specification (1) n unfortunately, most web page authors concentrate only on the look of the page (by heavily using the procedural markup oriented tags) n the introduction of the HTML 4. 0 specification attempted to distance the content of web pages from formatting issues Clarke, R. J (2001) L 909 -05: 18
Stylesheets and Markup HTML 4. 0 Specification (2) n this standard encouraged reduction in the use of formatting (procedural) markup like <FONT>…</FONT> and <H 1>. . . </H 1>, <H 2>. . . </H 2> etc. tags n formatting was assigned to a separate standardization effort related to content style- Cascading Style Sheet (CSS) n provided the means to pass the decision as to how a paragraph looks to a style definition Clarke, R. J (2001) L 909 -05: 19
Stylesheets and Markup Link between Stylesheet and Content n In HTML, the link between a style sheet and the content it influences is either: n tag name of the HTML element that holds the content or, n an identifier associated with the element by way of an attribute (eg. ID or a CLASS attribute) Clarke, R. J (2001) L 909 -05: 20
Stylesheets and Markup Cascading Style Sheets n Cascading Style Sheets (CSS) allows authors to define style rules to each HTML element and these rules may apply to either: n single elements n a related group of elements, or to n all elements of a particular type (such as all P elements) Clarke, R. J (2001) L 909 -05: 21
Stylesheets and Markup Style Rules in CSS (1) n style rules influence the rendering of elements n colour, alignment, border, margins, and padding between borders and content n can also control special items eg. whether Ordered List (OL) elements use bullet symbols, letters or roman numerals Clarke, R. J (2001) L 909 -05: 22
Stylesheets and Markup Style Rules in CSS (2) n every style rules have two parts: n one or more elements or groups of elements that have style sheets defined for them n one or more style sheet attributes that apply to the elements n then need to relate or bind stylesheets to HTML elements (eg. to all P elements)several possible approaches Clarke, R. J (2001) L 909 -05: 23
Stylesheets and Markup Approaches of Binding n two major approaches to binding stylesheets to HTML elements n in-document styles n importing external stylesheets n the choice of approach depends on: n the size and complexity of the web site n the size of the development team n user community diversity and expertise Clarke, R. J (2001) L 909 -05: 24
Stylesheets and Markup In-Document Style Binding (1) : <BODY> <H 1 STYLE= “color: red; text transform: capitalize”>Some heading</H 1> <P STYLE=“color: blue”>Some paragraph text</P> : <BODY> Note: almost every HTML element can have a STYLE attribute associated with it n One form of In-Document Style Binding associates a style declaration to an HTML element using the elements’ STYLE attribute n Usage: n convenient if style rules are few and simple n difficult to maintain in large sites as changes must be made throughout the HTML file Clarke, R. J (2001) L 909 -05: 25
Stylesheets and Markup In-Document Style Binding (2) <HTML> <HEAD> <STYLE TYPE =“text/css”> <!-H 1 {color: red; text-transform: capitalize} P {color: blue} Note: style rules are enclosed in HTML --> comments to prevent </STYLE> older browsers from : trying to render them : : <BODY> <H 1>Some heading</H 1> <P>Some paragraph text</P> </BODY> </HTML> n Another form of In. Document Style Binding is to define and group together all style rules between <STYLE>… </STYLE> tags n Usage: n better option when trying to maintain a moderately complex page n promotes modular design and implementation of page Clarke, R. J (2001) L 909 -05: 26
Stylesheets and Markup Binding using External Stylesheets H 1 {color: red; text-transform: capitalize} P {color: blue} Note: these style rules are stored in the file called mystyles. css <HTML> <HEAD> <LINK REL=STYLESHEET TYPE=“text/css” HREF=“mystyles. css”> : Note: rules are applied </HEAD> to HTML file on the fly <BODY> <H 1>Some heading</H 1> <P>Some paragraph text</P> </BODY> </HTML> n Define and apply an external style sheet file to one or more HTML files n the external style sheet file (above, left) contains only rules no HTML tags n Usage: n promotes a consistent look similar to work processor style sheets n separates the documents’ structure and look Clarke, R. J (2001) L 909 -05: 27
Stylesheets and Markup Difficulties with HTML (1) n While the CSS Level 1 is consistent across major browsers, it doesn’t provide exact positioning of elements on a page n the CSS Level 2 standard supports exact positioning but there are differences in implementation across major browsers n 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! Clarke, R. J (2001) L 909 -05: 28
Stylesheets and Markup Difficulties with HTML (2) n there is a much more serious problem: n the stylesheet and descriptive markup capabilities of HTML 4. 0 and DHTML (HTML 5. 0), were not built into it from the start n describing the structure is not the same thing as descriptive markup n users cannot create there own tags based on meanings (semantics)- for example no tags for PART NUMBER or COURSE- HTML not extensible Clarke, R. J (2001) L 909 -05: 29
Stylesheets and Markup Difficulties with HTML (3) n on the Internet simplicity wins over efficiency- the Web has grown because its core standards are simple: n proof of this is that HTML is itself written using another standard for describing documents- this standard is called SGML n SGML has also been used to develop a standard likely to replacement HTML on the web- XML described in Lecture 13 Clarke, R. J (2001) L 909 -05: 30
SGML Standard Clarke, R. J (2001) L 909 -05: 31
SGML Standard n internationally recognised standard (ISO 8879) for describing and enforcing structure and properties onto data in computer base information systems, including semi-structured data n completely descriptive markup system for document content n open environment for the interchange of a portable generic format between platforms Clarke, R. J (2001) L 909 -05: 32
SGML Standard Features (1) n major features: n syntax for text processing stylesheets n extensible document description language n meta-language for defining document types n text media support: n text is coded according to its meaning- can be used in way not originally envisioned n tagging language n database language for text Clarke, R. J (2001) L 909 -05: 33
SGML Standard Features (2) n media processing applications: n foundation for multimedia and hypertext- Hy. Time (an ISO standard) is an SGML application that knows about multimedia, time-based events, synchronisation n general computational features: n handles logical structures (conditional documents) n notation for structures (eg. hierarchies): sequences, repetitions and selections Clarke, R. J (2001) L 909 -05: 34
SGML Standard Features (3) n other aspects: n general file linking and addressing scheme n open document representation language for any system architecture n supports open inter-communication regardless of hardware platforms and software applications Clarke, R. J (2001) L 909 -05: 35
SGML Standard Instances & Document Type Definition n An SGML document is text only, but has the following structure: n an document instance containing the data n a document type definition (DTD) defining what data elements can be in the document, and how these data elements relate to each other Clarke, R. J (2001) L 909 -05: 36
SGML Standard Document Instances n document instances contain data and markup (called tags): n both data and tags are in ASCII format- read by any application n tags are distinguishable from data: tags always have pairs of <> brackets n some system specific data can be inserted into the instance using special tagsremoves the need for control codes etc Clarke, R. J (2001) L 909 -05: 37
SGML Standard Document Type Definition (1) n can be stored at the beginning of the document or externally in a separate file (generally the latter) n consist of all the formal definition of the elements, structures, and rules for marking up a given type of SGML document Clarke, R. J (2001) L 909 -05: 38
SGML Standard Document Type Definitions (2) n comprise rules and relationships that define how the different elements within a document relate to each other: n specify the order in which headings occur n which elements are allowed under each heading n the order and frequency with which elements should appear Clarke, R. J (2001) L 909 -05: 39
SGML Standard Document Type Definitions (3) n specifies the permitted document elements n eg. ‘Chapter’, ‘Heading’, ‘Definition-entry’, ‘Defined-work’, ‘Definition’ and ‘See-also’ n each element typically has a content model stating its required or permitted contents. n eg. the content model for ‘Definition-entry’ would state that it must have only one ‘Defined-word’ and ‘Definition’ n ‘Defined-word’ and ‘Definition’ must also be described by content models Clarke, R. J (2001) L 909 -05: 40
Document Type Definition Extract 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 > : : Clarke, R. J (2001) L 909 -05: 41
SGML Processing Systems (1) n read a document instance, and refers to a DTD to find out how to process it n aspects of the document instance such as format of the page, fonts spacing etc. are not defined in SGML (a distinction between Post. Script for example and SGML) n must exist in heterogeneous environments where not all documents are in SGML Clarke, R. J (2001) L 909 -05: 42
SGML Processing Systems (2) SGML Data Application Library SGML DTD SGML Parser SGML Processing System Application Output Clarke, R. J (2001) L 909 -05: 43
SGML Processing Systems (3) Tag Application New Data SGML Applications New Data Legacy Documents Graphics Files Non-SGML Editing System SGML Files SGML Edit/Convert Bitmap Edit/Convert Clarke, R. J (2001) L 909 -05: 44
DSSSL n Document Style Semantics and Specification Language (DSSSL) n is the ISO international standard (ISO DIS 10179) which addresses the need for detailed, typographically sophisticated, specification of layout and composition n independent of particular formatting systems or processes Clarke, R. J (2001) L 909 -05: 45
SGML Example Clarke, R. J (2001) L 909 -05: 46
SGML Example Informational Content Markup n the following two slides shows an extract from a Vincent motorcycle repair manual n show the informational content markup using SGML n note that SGML tags are usually shown in the form <…> followed by </. . > Clarke, R. J (2001) L 909 -05: 47
Information Markup (Source: Nicholson Brothers Motorcycles Ltd. 1994) Clarke, R. J (2001) L 909 -05: 48
Information Markup (continued) (Source: Nicholson Brothers Motorcycles Ltd. 1994) Clarke, R. J (2001) L 909 -05: 49
SGML Benefits Clarke, R. J (2001) L 909 -05: 50
SGML Benefits n DTD structure forces the user to focus on document content not format n SGML helps the authors by: n suggesting the correct structure of different document types n enforces the correct structure: if an author attempted to put in non-standard material, the application would refuse to accept it Clarke, R. J (2001) L 909 -05: 51
SGML Benefits n Data Management n common data repository for the enterprise n standardised formatting for information n minimise data duplication n control/check data quality n maximises the benefit of data entry and authoring Clarke, R. J (2001) L 909 -05: 52
SGML Benefits n facilitates data exchange within an enterprise (Intranets) n prevents islands of information forming within the organisation (that is information trapped within specific functional areas) n prevents an ‘isolationist mentality’ forming within specific functional areas (‘marketing’ data rather than organisational asset) Clarke, R. J (2001) L 909 -05: 53
SGML Benefits n facilitiates data exchange between an organisation and business partners (Extranets; EDI) n promotes participation between partners n reduces costs, improves performance n streamlines operations and maangement practices, reduces ‘bottlenecks’ Clarke, R. J (2001) L 909 -05: 54
SGML Benefits Video Case Studies about EDI n Note that SGML could well have been an enabling technology for EDI in these CASE Studies n take notes on how these EDI systems were negotiated- what are the Tactical Strategic and Operation implications suggested in these cases Clarke, R. J (2001) L 909 -05: 55
Adopting SGML Clarke, R. J (2001) L 909 -05: 56
Adopting SGML n Data Analysis n Feasilbility Study n Standardising Data Concepts n Data Entry & Document Conversion n Delivery of Data to Users Clarke, R. J (2001) L 909 -05: 57
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