IMAGES AND SOUND CLIPS IN WEBPAGES

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INTRODUCTION

When a computer user displays an internet screen on his local computer, the work of displaying the webpage is done by a program called a browser. This program executes on the user's local machine. Usually, this browser is called Netscape or Internet Explorer.

When a webpage is requested by the user, the browser asks a remote computer, by way of the internet, to supply one or a even a large set of files containing a strange language called the Hyper Text Markup Language (or html, for short) addition to supplying the text, i.e., the words that are to be displayed, the html files contain information that instructs the browser with regard to how the text and images are to be displayed.

When a user asks for a webpage to be displayed by the user's browser on his own computer, the local computer makes a request of the appropriate server computer (where the files that comprise the webpage are held) to send to the local computer all of the files to generate the requested display. Essentially any user may request (and get) all of the files. However, to maintain a webpage, files must be sent in the opposite direction, i.e., to the server. This is a problem. A browser can not do this. A secure server computer will not allow just anyone to modify any files on the server. This requires special authority. This permission is given to the webmaster, and no one else in the outside world. Therefore, the webmaster is responsible for installing all of the webpage files onto the server computer.

All of the files for a typical webpage fall into only a few categories: .htm for the text and instructions, .jpg, .gif and .png for images and .au (and possibly .wav) files for sound recordings to be played while viewing the webpage screens. There are no text (.txt) files on the server because the server and local browser do not speak this language. However, to maintain a webpage, it is convenient for a user to create and maintain .txt files. Nevertheless, the .txt files must be converted to the .htm files that the browser does understand. This translation is the job of the webmaster.

THE TRANSLATION PROGRAM, jhlHTML.exe

A program has been written to read the lines of text (which are supplied by a user) for insertion into a webpage and to translate the lines of text into the html language. The user maintaining the information content of the webpage supplies the webmaster with only a simple text file. (note: the user must also supply to the webmaster the .jpg or .gif image files for inclusion into the webpage.) Using a translation program in this manner means that the user does not need to be familiar with any of the details of the html computer language yet the user will still have quick access to supporting a webpage for an organization and retain complete control over the webpage content.

Nevertheless, as simple as this process can be, the user preparing text for the webpage needs to know how the text should be organized so as not to confuse the translation program.

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COMMANDS TO DISPLAY IMAGES AND PLAY SOUND CLIPS

The command %I is used to display an Image that is to be displayed centered on the page, %J for an image that is to be displayed right justified on the page (to allow text to flow to the left to produce a rather pleasing change to the more sterile one thing over the other), %W is available to play a sound clip when the webpage is loaded.

 
   %I  file_name text    Insert a reference to an image, to be centered on
                         the page and put 'text' for the LYNX ALT option.
   %J  file_name text    Insert a reference to an image, to be right justified
                         on the page (to allow text to flow around the image
                         to the left of the image and put 'text' for the
                         LYNX ALT option.
 
   %W  file_name         Cause the .AU sound file to be played