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As the Web continues to explode in its own inimitable fashion, it is becoming more and more important to write HTML that conforms to certain guidelines. Specifically, with the current diversity of clients for the Web (and we can only expect to see more!), it's become important to write HTML that will look good on any client, and not just on the specific client which the author may have access to.

Some Definitions

• WWW: World Wide Web (or Web, for short).
• SGML: Standard Generalized Markup Language, a standard for describing markup languages. Learn more about SGML by reading "A Gentle Introduction to SGML"
• DTD: Document Type Definition, a specific markup language, written using SGML.
• HTML: HyperText Markup Language is a SGML DTD. In practical terms, HTML is a collection of styles (indicated by markup tags) that define the various components of a World Wide Web document. HTML was invented by Tim Berners-Lee while at CERN. He is now director of the W3 Consortium.
• CERN: Centre Européen de Recherche Nucléaire, the "Grand-daddy" of the Web.
• ISP, Server or Site: Internet Service Provider, the computer you dial up from your office or home. Ours is NetReach International
• Client: the end user, as in "you and me". Clients use Browsers.
• Page or Document: a single entity stored normally as a file.html, often more than will fit on one screen.
• Browser: the software that is loaded in a Client computer to view Web pages: Netscape Navigator, Microsoft Explorer, NCSA Mosaic, Symantec CyberJack (all © ® ™ just to keep things straight!) are examples.
• http: Hyper Text Transfer Protocol, the method by which Web pages are transmitted.
• FTP: File Transfer Protocol, ditto for Files.

What is HTML Level 3?

(HTML Level 1 is the original version. HTML Level 2 is essentially the same, but with the addition of forms.)

HTML Level 3, also known as HTML+, is an enhanced version of HTML designed to address some of the limitations of previous versions of HTML. HTML Level 3 supports true tables, right-justified text, centered text, line breaks that do not double space, and many other desired features.

However, most clients support only a handful of HTML Level 3 features (such as the partial implementation of tables in Mosaic) at the time of this writing. If you have access to a Unix system with the X Window System installed, you can try out many features of HTML Level 3 using the experimental Arena browser.

You can access information about new developments in HTML at the CERN server., which at this reference gives general information about HTML including plans for new versions. Users should be aware that HTML is an evolving language, and different World-Wide Web browsers may recognize slightly different sets of HTML elements. There is also a comprehensive list of HTML elements amongst several others.

Servers

What kind of connection you need for your server? Here are some basics.

If you reckon no more than 4 or 5 seconds to send a page (allow more time for external images/audio/etc), how large can a page be? Start by ignoring ISP overhead on the line, compression on modem lines, and anything that's less than about 10% of the total, but remember the multiple packet round-trips it takes to get data flowing through a HTTP channel. For modem lines, this is nearly a second for each HTTP connection, which is significant. For dedicated lines, it's nearer a tenth of a second, which is not significant.

With a 14.4 line (sending under good conditions 1.4Kb bytes of data/second) there is the one second startup, so you get 4 * 1.4 or 5.6Kb of HTML. If you want to include a single inline image, that's 2 seconds of startup, so you're down to 3 * 1.4 or 4.2Kb of HTML plus the image. This means smallish HTML pages, and simple inline images which have to be kept small.

If you have a 28.8 line, you might get double those figures; for a 9600 line, figure 2/3rds of that size. But with a 56K dedicated line (assumed to be sending 5K/second) you get 25K of HTML, or mixed HTML/data.That should cover any reasonable HTML document, and small to medium external files. An MPEG movie might be a bit much. For info, T1 lines are assumed to be sending 150Kb/second, and Bell Canada is beginning, very slowly, to introduce ISDN lines, with a total bandwidth of 128Kb.

Access time

Simultaneous access is not necessary unless the site is very large and needs as much bandwidth as is affordable for the price, you the Client pay. Under the worst case conditions, the Server uses all of its line for HTML pages, each of which takes 5 seconds to send, so your server is sending 12 pages a minute, or 720 pages an hour, or 17,000 pages a day (pages, not accesses; each inline image in a page generates an access, unless the client cached it). This makes it one of the busier sites on the Web.

While there will be contention problems (the "rush hour", when the kids get home from school!) before getting to this point, anything but a modem connection will be sending most pages in a small fraction of five seconds, which should leave plenty of bandwidth with no contention.

The bottom line on simultaneous access is that the WWW server is more likely to have contention with other uses of the line than with itself. Since only your ISP knows what else they use their lines for, you will have to consult your Server on that issue yourself.

Security

" . . . as the Web turns . . . "

An update on this subject will be out very shortly, but if your Browser asks you about "Cookies" (if you have not turned that function off), you may well have a problem. Recent innovations, including CGI, Java etc, can invade your privacy at the very least, and possibly be much more dangerous.

On a related matter, "JUNK E-MAIL", or spam, is probably beginning to creep into your life. We are currently making a major effort to investigate the practical and legal implications of what appears to be a definite invasion of privacy. If you have any examples, horror stories or suggestions, please share them with us.

But remember, hackers can and will get into Net Sites and your computer. It is neither difficult nor rare.We will update this subject as soon as possible.

Browsers and Page development

Any Page on the Web should be developed using several different client programs, to ensure that it is formatted it in a manner that is device independent. We use various versions of Netscape Navigator, Microsoft Explorer, NCSA Mosaic, and Symantec CyberJack (all ©®). Both Netscape 3 and Explorer 3.0, the most recent versions, use HTML 3, but each with their own slight foibles.

For example, if the Index (or Menu), in the frame to the right of your screen uses word wrap and you can read every word, you're using Netscape; Microsoft makes you work by installing a scroll bar at the bottom. If you can't see the Index Frame at all, you're maybe using Mosaic or CyberJack

We are not going to get involved in the discussion of their relative merits , but could recommend that, regardless of which one you favour, you get the most recent version.

We tend to use Netscape Navigator more than any other, as on our machines it is less expensive on memory and reacts a lot faster to certain commands. (Try [Top of Page], then come back here with [Browser development]. Netscape is just about immediate, Microsoft appears to reload the Page completely, and we hate waiting.)

Developers should also ask themselves:

• Is the Page interesting, eye-catching and easy to use? Are there eny speling misstakes?
• Are some parts not being read, perhaps because people are looking in the wrong place for them?
• Have you made it clear that you welcome criticism or suggestions from your readers, and how they should send it ?
• Have you asked people to solve problems using the document, and report on their success? If they fail, have you found out what they were looking for and whether it was in the document at all?
• Are you respecting the Client's privacy? Or are you sending, perhaps with very good intentions, Cookies or other means of identifying and cataloguing readers of your document?
• If you use Frames, have you taken older, non frame-compliant browsers into account, as we have tried to do on these Pages?