Using the Network by Accident

Some of the most common network services hide the network from the end user. You can think of these services as causing the end user to use the network by accident because he doesn't realize the network is involved in the tasks he's performing.

To explain these "accidental" network services, I'll use an imaginary employee at a remote office. We'll call this fellow Fred. Fred is the master of his own domain; he has a PC, a printer, and he can do all his work without much interruption from the home office. To perform his normal daily work, Fred opens a document using a word processor, changes some of the text, and prints a copy. He then mails the letter to the customer and saves the changes to the letter. Figure 2-1 shows the basic idea.

Figure 2-1. Fred's Normal Daily Tasks on His Personal Computer

The steps in the figure are as follows:

1.	The word processing program reads the letter from the disk drive.
2.	When Fred clicks the Print icon, the PC sends a copy of the letter to the printer.
3.	When Fred saves the file, the word processing program writes the file back onto the hard disk.

Step 1 is often called a file read, which means that the computer copies the file from a disk drive into computer memory so that the computer can process it. Later, by performing a file write, the computer replaces the old file on the disk drive with the newly revised file.

Fred's life is good for a while, but like all things, changes eventually happen. Fred's company grows, and he can't keep up with the work. So, the home office sends a hotshot, named Wilma, to Fred's remote office to work with him and help him get all the work done.

Wilma brings her super-dooper, fast high-end PC with her to the new office and installs a network. She also takes over Fred's old printer and connects it to her own PC. Being a control freak, Wilma also copies all the customer letters from Fred's PC over to her PC. Figure 2-2 shows the general concept, similar to the simple LAN from Chapter 1, "What Is a Network?"

Figure 2-2. A Network with Fred and Wilma

Wilma set everything up, including the network, so she knows how it works. However, Fred has no idea why the new gal would mess things up like this. So, the first morning, after getting his cup of coffee, Fred starts up his word processor, grabs a diskette, and walks over to Wilma's super-dooper new computer and copies a customer letter onto the diskette. He walks back to his desk, updates the letter using his old clonkey computer, and then walks back to Wilma's computer with the diskette. Then Fred copies the file back onto Wilma's computer, replacing the old file, and brings up the word processor on Wilma's computer so that he can print a copy for mailing to the customer. Figure 2-3 shows the idea.

Figure 2-3. Fred's "Sneakernet"

In this example, Fred does not use the network. He instead uses something called Sneakernet. Sneakernet is a sarcastic term that refers to the process of not using a real network, but instead walking back and forth between computers with diskettes or CD-ROMs, moving files manuallyand requiring comfortable sneakers!

Fred's Sneakernet method works, but it's way more time consuming than before the home office sent him help in the form of Wilma. Finally, Wilma gets to the office and finds Fred putting on his comfortable sneakers, getting ready for lots of walking around the office.

"Fred, I guess I forgot to tell you how to use the network! You don't even need to know it's there! If you just look on your C drive in the folder called Customers, you will see all the same files you are used to working with. The files are on my PCa file serverbut that's hidden from you. Also, when you click on the Print icon from your word processor, you'll see a printer called sameoldprinterclever name, huh? If you print to that printer, it will print on your same old printer, eventhough it's connected to my PC. My PC is set up as a print server, so you can print on your same printer. You can do your job the same old way, from your old clonkey computerbut you can still wear your sneakers if you want to!"

For this network to work, Wilma's computer provides file services. File services include the process by which one computer, typically called a file server, keeps files on its disk drive and allows other computers to read to and write to the files by using the network. The term "file server" refers to the computer that provides the service of storing the files on a disk drive and making them available to others for reading and writingin this case, Wilma's computer. (A disk drive is a component of a computer on which you can store files permanently.)

Similarly, Wilma's computer provides print services, the process by which a computer allows other computers to print files on a printer that is physically attached to the computer. Print server refers to the computer that provides printing services.

Fred's computer can still do the three steps that were shown in Figure 2-1, but hidden from Fred is the fact that the read, print, and write operations all happen over the network.

Remember: A network consists of software, hardware, and cabling that allow multiple computers to communicate successfully. Figure 2-4 shows the computers and a network cloud, with the cloud hiding unimportant details of the network. In this case, just like the users, we do not care about the details of most of the network yet, so the network is represented with a cloud.

Figure 2-4. Fred's PC Using the New Network

File and print services are two of the most typical network services found in an enterprise network. (An enterprise network is a network created for use by a single company or organization.) The users do not actually need or even want one printer on each desk; they simply share the printer located in a central area. They also probably want to use the same files as some of their co-workers. Transparent print and file services allow multiple users to share printers and files. The users can open files, modify them, save them, and print themdoing the same things they did before file and print servers existed.

The next section discusses a few end user applications that presume the existence of a network.