Pertemuan 17 Programming Languages for E-Business/E-commerce Matakuliah : M0284/Teknologi & Infrastruktur E-Business Tahun : 2005 Pertemuan 17 Programming Languages for E-Business/E-commerce
Learning Objectives Differentiate between HTML and XML and appreciate the role of XML in e-business Create an XML document that uses a simple cascade style sheet and displays its content in an IE browser Learn how to use an external document type definition (DTD) file to specify the document structure required for an XML document Write an extensible style sheet (XSL) to specify the formatting requirements of a document and appreciate how its programming features are used
Chapter Overview Languages used on the WWW Similarities and dissimilarities Advantages and disadvantages Understanding the newer technologies in the offing
Aspects of content delivery Languages for formatting and aesthetics (HTML, DHTML, Style Sheets) Structure and semantics of the content (XML) Scripting languages for processing of data and interface with external applications (CGI, Java Server Pages, JavaScript, VBScript, Coldfusion, PHP)
History of Web Originally availability and dissemination of information SGML – Standard Generalized Markup Language Had mark-up language, with hyper links, no complex features HTML- HyperText Markup Language DHTML – Dynamic HTML, more flexible Not standardized, no common standards adopted by the leading browsers.
XML – eXtensible Markup Language Supported by major players like Microsoft and IBM. Projected to be the most relevant web standard of the future. Best suited for E-Commerce (as front-end and back end sub- systems can be conveniently integrated).
PDF – Portable Document File Proprietary format from Adobe Best suited for distributing complex documents Preservation of original style, format etc. Freely available Reader (Adobe Reader), no charge for viewing the documents.
SGML – Standard Generalized Markup Language Born out of generic coding and mark-up languages in early 1970’s. SGML as a formal standard under ISO First edition in 1986 Amended in 1988.
SGML (contd.) Specifies a standard method for describing the structure of a document. Open-ended definitions Does not directly specify any type of content data, no restrictions on any type of data. Flexible, able to describe any logically structured set of information (e.g. form, memo, book, dictionary, spreadsheets, databases). Sophisticated, used by a loyal group of developers,
SGML - Not a markup scheme. But a means for describing any markup scheme. SGML can be used for developing markup schemes for different document classes.
Uses of SGML Publishing Multi-media Save and store information for long term (e.g. AAP, ATA, CALS etc.)
HTML – Hyper Text Markup Language Most prevalent form of web pages is HTML. Born out of SGML’s rejection, is easy to use. Both Microsoft I.E. and Netscape Communicator support it. HTML content can be formatted with the addition of a few tags. Can be created using dynamic code generators or templates Word processor files, even MS-Excel, Access and PowerPoint files can be exported to HTML.
Advantages and disadvantages of HTML HTML has pre-defined tags, both a strength and a weakness, depending on the user’s experience. Elements of HTML include title, body, background, paragraphs, lists, tables, forms, formatting (bold, italics, underline) Can add Java applets and ActiveX controls within HTML pages. HTML can be developed using editors ranging in complexity from MS Notepad to WYSIWYG. Limitation – tags cannot be created for new un-defined structure, format.
Insertion of pictures and graphics in HTML One of the main reasons for the success of the WWW. Inline images, hyper-linked images (stored on a different page). Types of raster graphics: GIF, JPEG, PNG, no need for plug- ins.
Syntax for inserting a picture <html> <head> <title> Picture of a dog </title> </head> <body> <IMG SRC = “dog.jpg” border = 0> </body> </html>
Other features Align – takes values bottom, top, left, middle and right. Alt- an alternative message Border – defines border width Height- height of the image and allows resizing HSpace- horizontal space SRC- URL of the image VSpace- vertical space Width – width of the image and allows resizing
Most common HTML tags <html> </html> Marks the beginning of the document and end <head> </head> Specifies the beginning and end of header <title> </title> Indicate the title ; not displayed on web page <body> </body> Indicates the main part of web page <hn> </hn> Specifies the size of heading from 1 (large) to 6 <p> </p> Delimits a paragraph with a blank line <li> </li> Delimits the beginning and end of unordered list <hr> Inserts a horizontal line <br> Indicates a cut in the flow going to next line <b> </b> Indicates that the text within is emphasized <i> </i> Indicates that the text within is italicized <u> </u> Indicates that the text is underlined <table> </table> Inserts a table in the document <form> </form> Inserts a form in the document
Background color <body bgcolor = “#99CCFF”> Here, 99 denotes red, CC denotes green and FF denotes blue in hexadecimal notation. or <body background = “lightgreen.jpg”>
For additional functionalities, we might want to add Java applets <APPLET CODEBASE=“..” CODE=“hm30.class” NAME=“HotMedia” WIDTH=“239” HEIGHT=“50”> <PARAM NAME=“mvrfile” VALUE=“data/preview.mvr”> </APPLET>
Links to other pages Hyper-links- most attractive feature in Hypertext media. Makes navigation through the pages very convenient. Useful for e-commerce also, as it can be used to balance and distribute the load among various servers. Delegate time consuming operations to the service providers. <A HREF=“second.htm”> second page </A> Here <A> and </A> act as anchors for the link. HREF indicates the URL of the target page.
Web publishing A web server should be running on the computer where the document to be published is located. FTP (File Transfer Protocol) allows remote insertion of pages on a web server.