Al's TAFE Certificate IV I.T. (Website Design) Exercises

Semester TWO

Emerging Web Technologies and Standards » This is a supplementary subject.

"There will be no future versions of HTML. Instead XML and its applications have come to the forefront!" from 'Integrated Web Design' by Molly E. Holzschlag, New Riders Press, 2003

The web and Internet is not the same today as it was 3 years ago. It will not be the same in 3 years time. To work successfully in the area of Web Design and Development you need to realise that the field you are working in is constantly evolving. That means that unlike many other professions you will need to be constantly learning and adapting to new technology and trends. For example HTML is on the way out but XML and XHTML and CSS is in and becoming the way of the future for page development. That is just one small example. To be effective in Web you need to understand these new directions and be ready to ride the wave of change before it passes you by.

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Web Standards and Protocols

Some Emerging Technologies

SVG (Scalable Vector Graphics)

"A Short History of XML and SVG

XML has sprung into existence seemingly overnight, but this appearance is deceptive. XML has, much like the Internet, gestated under a number of different forms since the late 1960s. During that decade, Charles Goldfarb, Edward Mosher, and Raymond Lorie of IBM faced a conundrum: how to effectively store electronic documentation. The solution they came up with soon came to be known as General Markup Language (GML), which was a way of providing a logically cohesive structure to a document that could in turn provide metadata about that document.

GML proved to be something of a hit in the early 1970s, and others began to provide their own implementations of GML. Unfortunately, although there was a great deal of similarity between these various markup languages, there were also a sufficient number of differences to make building tools for GML next to impossible. As a consequence, the adopters of this technology agreed to create a standard, called Standardized Gener alized Markup Language (SGML), which was adopted by the United Nations (through the International Standards Organization) as a key standard for markup languages worldwide in the early 1980s.

SGML was an extremely powerful way of expressing a wide range of documents, but the growth and fracturing of SGML meant that the standard was also so sufficiently complex that it was difficult to implement on any but the largest machines. SGML consequently went into a decline after becoming a standard; it was still widely used but with far less activity going toward improving it during the period of intense growth in the computer industry between 1980 and 1992.

Examining PostScript

Another standard emerged in that same interval, however: PostScript. This language is a page-description language, or a theoretically human-readable standard for describing graphical content, including both pictures and the letters of words. Adobe Systems created PostScript in the early 1980s as a way for printers to universally describe how a page looked, and it was such a success that PostScript-based printers currently dominate the printer market.

It's worth examining PostScript in some detail because PostScript provided an interesting paradigm that has made its way into SVG: the use of plain text to describe graphical information."

SMIL (Synchronized Multimedia Integration Language)

Listing 26-1: A simple SMIL file
< smil>

 <head>
 <root-layout width="320" height="240"/>
 </head>

 <body>
 <seq>
 <audio src="rtsp://my.server.com/audio.rm"/>
 <video src="rtsp://your.server.com/video.rm"/>
 </seq>
 </body>

</ smil>

All SMIL files must begin and end with the < smil></ smil> tags. After the opening < smil> tag, the layout of the presentation is defined in the header section. The header section is enclosed with <head></head> tags, and contains a single line of code which defines the size of the presentation. In this case, the size of the presentation is 320 x 240. Following the header section is the body section, which is enclosed by the <body></body> tags. In this body section, two media streams are contained within <seq></seq> tags, which specifies that they are to be played in sequence. In this presentation, the audio.rm file on my.server.com is played, followed by the video.rm file on your.server.com . The preceding example is not so revolutionary. In fact, you might be tempted to ask why eleven lines of code were necessary to play two simple files back to back when you could accomplish the same thing with two lines of code in a metafile. To answer this, take a look at a typical television program and break it down into its component parts. Figure 26-1 is an artist's rendition of a typical sports program. It may look like any other television program, but a closer inspection reveals that it is a particularly information-rich presentation. The announcer talks about the day's sporting events. As he speaks, photos of the various stories are displayed over his shoulder. During the whole presentation, scores from various leagues are displayed along the bottom of the screen. Last but not least, the sports network's logo is displayed in the lower right hand corner — a persistent reminder of who owns the broadcast.

broadcaster

Figure 26-1: A typical sports television broadcast consists of different types of media.

We see the program as a single presentation, but it actually consists of four separate elements:

Before the television program can be broadcast, it must be assembled in the television studio from the individual parts. The four separate elements are produced individually and combined using powerful video broadcasting tools. The resulting video is sent to the television station's antenna or satellite and broadcast to the audience. This modularity gives the program a large degree of flexibility. By separating the program into its component parts, different people can be assigned to different parts of the broadcast. A few simple keystrokes can change whether the images are displayed on the right or left. The scores along the bottom can be made to disappear if desired. The component parts can also be re-used. The sports scores could be used in the evening news, or the broadcast could be licensed to a third party with the logo in the lower right-hand corner removed. SMIL mirrors this modularity in software. By allowing the author to specify multiple data types and different regions, a large degree of flexibility is provided. Streams can be combined and re-used, moved around in both time and space. This flexibility provides not only a large degree of freedom for the author, but more importantly, significant bandwidth savings, which enables the creation of rich multimedia presentations at low bandwidths

SOAP (Simple Object Access Protocol)

Web Services

Web Services and SOAP — A Joint Venture

Web services were conceptualized when it became essential for enterprises running on disparate systems to provide an integrated solution for enhanced business productivity and customer satisfaction. Here is a short scenario that highlights the importance of Web services.

Consider two enterprises that are using Linux and Windows operating systems each. One of the enterprise hosts a Web site that allows customers to place orders for computers. These computers are manufactured by the second enterprise. The Web site hosted by the first enterprise needs to query the catalog of the second enterprise to ensure that the required quantity is available.

Therefore, you need to devise a mechanism by which the two enterprises, running different systems, can share data in real time. Such a mechanism can be easily implemented by XML-based Web services. By implementing XML-based Web services, you can create Web methods that allow a Web service client to connect to the Web service and retrieve the quantity of one or more brands of computers available in the inventory. This Web service and the Web service client communicate by using SOAP messages.

From the above discussion, the following advantages of Web services can be interpreted:

To enable Web service clients to utilize a Web service, a discovery document is required. The discovery document enables a Web service client to discover and call the methods exposed by a Web service. The discovery document is written in Web Services Description Language (WSDL).

The UDDI Initiative

Emerging Web Technologies and Standards Links

W3C

Web Standards Project

ECMA

IEEE

IETF

What are web standards and how should I use them?

Internet Protocols

HTTP

HTTP made easy

CGI made easy

MIME Tutorial

SMTP

SOAP

SOAP FAQ

UDDI

UDDI (Cover pages)

UDDI Browser

WSDL

Web Services Tutorial