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Other technologies

Maybe, many of you have heard about technologies united under the label of "Dynamic HTML".

Of course, the statics of classical HTML files somehow opposes the dynamic nature of Internet. People get online mostly to take new information and they are not interested to read again and again the webpages not renewed for years.

I have already written about a technology which allows to create a web-page dynamically. On the left you can see small (well, very small) text fragment generated dynamically - the number of visitors. If you try to see the source code of the page, you will see the same number. But it does not mean that I manually write numbers for every visitor. In fact, there is a SSI command that forces the server to execute counter script and inserts the result into text. The user's browser does not see this command, because it is intended for the server, but receives output code.

So, using CGI it is possible to force the server to make entire page from various pieces. Such pages usually have the extension of .cgi. In browser's address window it is followed by the question mark and the string of input data. This is typical for search engines, which process the requests and form the results into pages.

CGI script is usually written in Perl, the platform-free programming language. It is fully functional program, what determines advantages and lacks of CGI. It is possible to write script with all necessary functions, but, as any program, the script certainly loads the server's processor. Moreover, CGI scripts can be potentially dangerous because of programmer's thoughtlessness rather than maulicius intention. That's why the free hosting providers extremely rarely allow clients to use their scripts or charge a fee as a compensation for testing scripts.

Above was the introduction. Now I'll tell about some alternatives to CGI.

Some time ago there was a boom of Java technology. The center idea of Java was a program code which could work in any operating system, interacting with it via software intermediate - Java Virtual Machine, created for every OS separately. For Internet it sounded promising: create the program, upload it to a server, and any user can download and execute it regardless of his hard- and software. The program have no direct access to the platform's resources and thus cannot damage the system. The server feels good too: nothing to execute, only thing to do is to give out the product to users.

Seems like everybody is satisfied. But in fact the idea was realized so poor that the technology is used primarily by enthusiastic webmasters whose time spent on learning Java must be proved.

Then Netscape invented JavaScript. The instructions based on Java syntax inserted directly into HTML allow to make a lot of various things. For example, it is possible to alter the look of page after downloading straight on client's machine.

First this technology was supported by Netscape Navigator, later, beginning with third version, by Internet Explorer as well. Now JavaScript is practically standard.

Some time ago I thought to use JavaScript on the site: to make extendable navigation menu, to show photos in separate windows cut exactly to the picture size. But studying the technology I realized that it looks like shooting sparrows with cannon. My aims were not worth efforts required for detailed study of JavaScript. I came back to my senses and fulfilled the idea of regulating the site by simply redesigning the tree of folders and pages. It turned out very useful for myself - to maintain the site is more convenient now. And to show photos it is possible and simpler by means of HTML.

Moreover, JavaScript successfully inherited some lacks of Java, and browsers often display messages of JS errors. It is not good.

When creating web-server solutions (Internet Information Server and Personal Web Server), Microsoft embedded into them the technology of ASP (Active Server Pages). ASP solves practically the same problems as other server-side technologies. But it is not actual for amateur webmasters, because this thing is available on Windows NT. In other words, if you see the extension of .asp in URL, it means that the server works under NT. But free (and most of commercial) hosting is under *nix family of systems only. However, some time ago I heard on news that in future the Apache server will support ASP. Maybe, ASP can be on free servers soon.

Without big noise there appeared the technology called PHP (Personal HomePage), which becomes more and more popular now. It was invented by one man for his personal purposes. As usual, the thing done for own needs (means done well) turned out useful for other people.

Principally speaking, PHP belongs to the class of CGI. It has the syntax which resembles SSI and can fulfil the same tasks. But PHP also can work with databases, and its instructions are inserted into page directly instead of separate file of CGI-BIN directory. The advantages of PHP gained its popularity among webmasters. There are PHP modules for various web servers, including Xitami and Small HTTP Server. The pages containing PHP code may have extensions of .php, .phtm, .phtml.

I did not use PHP, because my server has no such a service, but if you desire to make really dynamic (it means not text and pictures moving across the page but real-time generating content) website, I dare to recommend you to pay attention to this technology.

To read about these technologies you can here:
ASP:
http://asp-help.com/getstarted/gs_aboutasp.asp
JavaScript:
http://hotwired.lycos.com/webmonkey/javascript/tutorials/tutorial1.shtmll
PHP:
http://hotwired.lycos.com/webmonkey/programming/php/tutorials/tutorial4.shtmll

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© Dmitry Alemasov

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