1.6 OTHER STUFF
1.6.1 Clients and Servers
• Some computers are set up to serve others as centers of activity, sort of like a campus library. Other computers are set up only as users, like bookshelves in a closed office. The server is open to all, while the private bookshelf has very limited access.
• A computer server will answer requests from other computers. These requests may be,
- to get/put files with FTP
- to send email
- to provide web pages
• A client does not answer requests.
• Both clients and servers can generate requests.
• Any computer that is connected to the network Client or Server must be able to generate requests. You can see this as the Servers have more capabilities than the Clients.
• Microsoft and Apple computers have limited server capabilties, while unix and other computer types generally have more.
Windows 3.1 - No client or server support without special software
Windows 95 - No server support without special software
Windows NT - Limited server support with special versions
MacOS - Some server support with special software
Unix - Both client and server models built in
• In general you are best advised to use the main campus servers. But in some cases the extra effort to set up and maintain your own server may also be useful.
• To set up your own server machine you might,
1. Purchase a computer and network card. A Pentium class machine will actually provide more than enough power for a small web site.
2. Purchase of copy of Windows NT server version.
3. Choose a name for your computer that is easy to remember. An example is ‘artsite’.
4. Call the Information technology people on campus, and request an IP address. Also ask for the gateway number, netmask, and nameserver numbers. They will add your machine to the campus DNS so that others may find it by name (the number will always work if chosen properly).
5. Connect the computer to the network, then turn it on.
6. Install Windows NT, and when asked provide the network information. Indicate that web serving will be permitted.
7. Modify web pages as required.
• This is a programming language that is supported on most Internet based computers.
• These programs will run on any computer - there is no need for a Mac, PC and Unix version.
• Most users don’t need to program in Java, but the results can be used in your web pages
• Simple programs can be written as part of an html file that will add abilities to the HTML page.
• CGI (Common Gateway Interface) is a very popular technique to allow the html page on the client to run programs on the server.
• Typical examples of these include,
- feedback forms
- information requests
• There are major search engines on the Internet.
• You can also install local search engines for your site.
• This is a programming method proposed by Microsoft to reduce the success of Java - It has been part of the antitrust suit against Microsoft by the Justice Department.
• It will only work on IBM PC computers running the ‘Internet Explorer’ browser from Microsoft.
• One major advantage of ActiveX is that it allows users to take advantage of programs written for Windows machines.
• Note: Unless there is no choice avoid this technique. If similar capabilities are needed, use Java instead.
• Two good formats are,
GIF - well suited to limited color images - no loss in compression. Use these for line images, technical drawings, etc
JPG - well suited to photographs - image can be highly compressed with minimal distortion. Use these for photographs.
• Digital cameras will permit image capture and storage - images in JPG format are best.
• Scanners will capture images, but this is a poor alternative as the image sizes are larger and image quality is poorer
- Photographs tend to become grainy when scanned.
- Line drawings become blurred.
• Screen captures are also possible, but do these with a lower color resolution on the screen (256 color mode).
• These are not video, but moving drawings/cartoons.
• Animations are limited, but are best done with animated gif files.
• Other options include,
- java programs
- special plug-ins such as shockwave
• Streaming built into Netscape for real-time video.
• We can also get special plug-ins that will allow us to see video files,
- MPEG very popular, good compression, and fault tolerant.
- AVI popular on PC platforms, but limited drivers elsewhere.
- Apple Quicktime.
• Real-time video conferencing is possible, but not yet practical.
• Sound files are poorly supported, and most require special plugins,
- real audio
- wav audio
1.6.11 Other Program Files
• We can connect any type of non-standard computer file to our pages, such as a Microsoft Excel file ‘.xls’.
• To do this we need to,
1. Put the file in our web directory
2. Link it to one or more HTML pages
3. Have the system administrator add this as a MIME type to the system.
4. When you click on the link to the file in Netscape it will ask you to choose an application. For an excel file you would want to choose ‘\program files\office97\excel’. This will automatically start when you choose the file next time. If you did not do step 3, or did not choose an application you would be asked to save the file.
• This is an excellent way to extend the capabilities of a web browser.
1.6.12 Fancy Stuff
• Compact Discs (CDs) are becoming a common way to transfer information. These will allow you to store up to 650 MB of data. When used they look exactly like another disk drive that cannot be overwritten. To make a CD the writers cost about $400, and writable CDs can be purchased for about $1-2 each. It will take 30-60 minutes for a CD writer to create a CD that is completely filled.