3. Design (cont.)

3.4 Technological Choices.

The Use of Appropriate Delivery Technologies

With the content of the web site analysed and understood, and the information architecture of the site designed it is now important to map this information architecture onto the appropriate delivery technologies. Almost certainly a range of these will have been under consideration during the high-level architectural design of the site (you only select information that you know you can deliver), but it is now time to formalise these choices. Select technologies that best accomplish your goals, that you have the skills and resources to work with, and that your audience can use.

Almost any prescriptive list of technologies and their characterisitcs is bound to be out of date by the time they come to be used. Below are some of the general benefits and constraints of some web technologies and tools as set out by IBM on their 'Ease of Use' site:

Hypertext Markup Language (HTML)

This is the primary technology used to create all web sites. Some of the elements in the most recent versions of HTML may not work with older browsers. You will need to choose a version that best meets your purpose and the needs of your audience. You can select additional technologies, such as a scripting language, to supplement HTML.

Benefits of HTML:

• Loads quickly (exception: Netscape waits for all table contents to load before displaying any of the parts)
• Can be learned and implemented easily (easy-to-use HTML editors are available)
• Can be augmented with sound, video, Java applets, and scripting languages such as JavaScript and VB Script

• Provides only limited control over the way your page will be displayed, and over the appearance of text
• Is not programmable and offers only limited response to user interaction events

Cascading Style Sheets

Cascading Style Sheets (CSS) were implemented in the Netscape 4.0 and IE 4.0 browsers. They provide a way to control and adjust layout for an entire site with a single document that defines each style.

Benefits of Cascading Style Sheets:

• Provide greater control over layout and typographic properties
• Facilitate consistency of appearance
• Separate content from layout and presentation, which makes the development of a web site more efficient and flexible
• Manage conflicts in style sheet specifications among documents, groups of documents, and user browser set-ups by using a "cascade" or system of preferences
• Allow users to override your font style, size, and color attributes with ones of their own choosing, which is especially important for users with vision impairments
• Allow style changes selectively
• Can be used in conjunction with JavaScript to provide features that give users a richer sense of interactivity
• Allow elements to be positioned efficiently, eliminating the need for memory-intensive transparent GIFs; files are smaller and open more quickly

• Require more time to learn and implement than other features of HTML
• Are not supported by older browsers
• Are supported in different ways in the new 4.0 browsers (some CSS features do not appear in IE 4.0, and some do not appear in Netscape 4.0)

Frames

Frames were developed as an extension to HTML 3.2 and are supported by the newer Netscape and IE browsers (3.0 and up). They create bookmarking and printing problems, so many designers avoid using them.

Benefits of Frames:

• Allow content pages to be developed independently of navigation pages
• Allow the user to scroll through content without scrolling the navigation and identification areas out of sight; navigation and identification areas are always available

• Present usability problems for tasks such as printing, bookmarking, searching, and using the browser back button
• May necessitate a no-frames version of your site to provide accessibility for users with older browsers or those with disabilities who use assistive technologies
• Add more complexity

Scripting Languages

Scripting languages such as JavaScript and VB Script are used primarily for client-side programming, while CGI scripts are often used on the server side. Client-side scripting allows for control and manipulation of HTML and Cascading Style Sheet elements.

Benefits of Scripting Language:

• Allows for interactive, network-aware, and cross-platform applications
• Is easier to learn than Java
• Adds dynamic and interactive behavior to a web page

• Behaves differently on different browsers and between browser levels
• Can be read by only some browsers as low as 2.0, and not by any 1.0 level browsers
• Cannot be read by some assistive technologies used by people with disabilities
• Is difficult to debug
• Provides limited functionality compared with Java applets

Before you start to implement your site, think about the HTML and scripting features that you will be using. This should be driven by demands from the content, the navigation and the visual style that you have adopted. A particular technology should not normally be used 'for the sake of it' (although in an educational context this may often happen), but because it conveys your meaning. A good principle is: no effect without meaning. Try and create a definite plan for the use of technologies and effects that will feed into your page designs. Also, be aware that it is difficult to use some features of Dreamweaver (CSS, behaviours, layers) without understanding the underlying principles of the base technology.

Java Applets

Java Applets allow you to encapsulate a piece of function and embed it in a web page.

Benefits of Java applets:

• Allow for interactive, network-aware, and cross-platform applications
• May be used within other applets or applications on the same page
• Are not yet supported well by assistive technologies used by people with disabilities

• Are not yet supported well by assistive technologies used by people with disabilities
• Must be downloaded before they can run, can be a lengthy wait
• Provide only limited access to system resources
• Function only when the web page being viewed is in a browser window
• Often require substantial memory, and the files remain in the browser cache until emptied

Can only be executed/run by Netscape and IE versions 3.0 or later

Plug-In Technologies.

To this basic list must be added the range of technologies that require specialised plug-ins to be loaded by the user: Shockwave, Flash, QuickTime, VRML, etc. The basic rule of thumb for these technologies is that they should only be used when the content requirements of the web site demand it. They all demand download and processor time, and may be beyond the technology of some of the potential audience - perhaps limiting the audience base of a site. If advanced animations, or 3-d worlds, etc. are crucial to getting an idea across, then they should be used.

As with the various HTML and scripting features discussed above, try and have a definite reason and plan for the use of applet and plug-in technologies. Try and have an argument for using each of the technologies you choose - write a rationale for your choices in your documentation. It needn't be lengthy.

The Use of Appropriate Development Technologies.

Every choice of a delivery technology implies the choice of an appropriate tool to encode the content of the web site. The choice between a range of tools all capable of doing the same encoding task will be determined by such factors as cost, compatibility with existing tools, skills of staff, efficiency and reliability of the code produced, etc. In the student environment these issues are not likely to be a key issue since you are usually asked to either to use a specific tool set, or you are free to experiment with trial versions of any tools that attract you. In a production environment, however, these choices are quite weighty.

These choices are made for you by our environment, to a large extent. So there is no need to justify and document your basic choices. If you use some unusual tool in constructing your site, however, you might mention it and justify it in your documentation.

Other Industrial-Scale Issues

It might be necessary to have a programme of assessment and evaluation of delivery and development technologies. These will lead to the laying down of company policies on tools used, policies which may act as constraints on a project. These policies will be influenced by financial and legal (licensing) issues as well as by purely technological factors.

The hosting of a web site - the choice of server technology and capacity, and who provides these facilities is a key issue for a high-volume commercial site. Again, costs and contractual factors will play as much part as the purely technical performance of a server.

The development of a system with complex server demands - such as a database system - has implications for the kinds of systems that have to be available for development and testing. The provision of 'parallel' development and delivery systems may be required.