File Transfer Protocol
File Transfer Protocol, hereinafter referred to as FTP, is one of the major applications available on the Internet. It's important because it allows you to take files from a remote computer and place them on yours--this is called "downloading." You can also do the opposite, should you be so inclined and the remote computer is agreeable--this is called "uploading." This is one of the foundations on which the Internet was built: the easy transfer of files from place to place.
Some of you may say, "why do I care about exchanging programs? I don't care about software. I'm no chip-head." Well, if you said that, you'd be wrong--it is very important to know about and keep-up with new application software. You wouldn't buy a car and say, "I don't care about gasoline, I'm no motor-head." Software is a driving force for ongoing innovation of electronic media technologies. It is a kind-of fuel for your computer!
You also need to know about FTP because it is via FTP that you will place your web page(s) on the web server.
Today, FTP is used to exchange application software (e.g., much of today's new software, such as new web browsers and plug-in components), text documents, images, sounds, and a whole host of other things that can be captured in a computer file. The important thing to remember about these items is that they require a computer which is software or hardware-equipped to handle them.
For instance, you may find files in an FTP site that will work on a Macintosh computer. It makes sense for you to download them only if you have a Mac on which to use them. Similarly, you may find text documents which are formatted for WordPerfect. If you don't have a copy of WordPerfect on your computer, or a word processor which can translate WordPerfect documents, you won't be able to view the document. The same can be said for many other files, particularly sounds and graphics.
I won't be able to teach you everything about FTPing in this lesson, but my goal is to get you started and give you an overview. For further information, I would recommend several of the Internet guides I mentioned in Lesson 1, including the ones on reserve for this class. Both of these, and a host of others, are available at the library. I encourage you to stop in and check them out (insert groan at library pun here).
Introduction to FTP
Worldwide there are hundreds of computer servers chocked full of software and information for you to download (copy to your computer). In this example, we'll focus on software archives. These archives are so popular that any one particular site might be inundated by eager users, and hence unavailable to any other users. The answer? Many back-up copies of these archives have been established to spread-out the workload among many computer archives. These back-ups are called "mirrors," as in mirror copies. These mirrors are spread-out strategically across the globe to make it easy to find and download via FTP.
Two of the most popular FTP software archives were developed at the University of Michigan (usually called Umich-mac or MERIT) and Stanford University (called Sumex-aim or info-mac). These archives originally started at their respective institutions, but quickly became too busy to handle all the traffic they attracted. Enter the mirror! Now, these two archives are backed-up at nearly 30 or more sites worldwide. This makes them available very quickly to nearly everyone on the Internet.
Browsing and Searching FTP Software Archives
Fortunately for us, much of the difficult work of FTPing (finding archives, searching for files, transferring files, etc.) has been automated and streamlined via the WWW. Several large web sites specialize in making FTPing easy and efficient. One of the most popular sites for FTPing on the WWW is a site called shareware.com (pronounced: shareware-dot-com), which is located at:
http://www.shareware.com/
At shareware.com, you can browse for software in the same way you can browse for books in the library or you can search for software titles which satisfy a particular request. Browsing works well if you know for what you're looking, or perhaps want to be surprised by what you find. Later I'll mention some sites you can browse. Searching is usually the preferred method, and it is FTP searching on which we'll focus.
First, point your web browser to shareware.com. Once you're at shareware.com, you should focus your search on the particular type computer system you use (Macintosh, MS-Windows, MS-DOS, etc.). This can be indicated by using the popup menu near the [Search] button (see image below). For this example, make sure to specify "Macintosh" BEFORE you perform your search!
Next, type in your search term in the space provided. For this example, type "gradebook" and then click the [Search] button. Shareware.com will find files which satisfy your request and return to you a list of these files. It will also display a brief description of the files it found.
As mentioned earlier, the most popular sites for the Macintosh are "info-mac" and "umich-mac." To ensure you will have a minimum of difficulty completing this activity, scroll through the list of found files until you find files from the info-mac or umich-mac archives. This information is mentioned next to the word "Location" in the next window (see below). These archives have many mirrors and, as a result, are often much faster than some of the other FTP archives.
Scroll through this list to find the names and descriptions of programs and other files available via FTP. A hyperlink at the bottom of the page (labeled "NEXT 10" or "NEXT 25") allows you to see additional selections.
The underlined file names in the center of the page are hyperlinks. Below the links are abstracts--short descriptions of the files. Read the abstracts to see which file you'll want to download. After reading the abstracts and choosing a file, select it by clicking once on its title (i.e., the blue underlined hyperlink title). Look at the image below to see how it should appear.
This will take you to the actual download page--a list of sites worldwide where copies of your selected file reside. Since your file is probably mirrored at 20-30 sites, you will see a list of 20-30 sites, each located at different sites from which you can download your chosen file. Note the sites locations--they span the globe! Click on the file name and, if all is right with the world, your file will be winging to your computer in a matter of seconds! If it doesn't work, just choose a different site. Look at the image below to see how it should appear.
Navigating Your Hard Drive
Your FTP browsing software (in this case, Netscape Navigator) will place the file on the hard drive of the computer you're using--but where? The answer to that question is determined by Navigator or whatever program you happen to be using to do your FTPing. If you don't find the downloaded file on your computer's desktop, then perhaps Netscape has placed the file in some other folder directory, perhaps the Netscape Folder or the computer's System Folder. Rather than manually hunting over "hill and dale" to find the file, simply use the Finder's "Find..." command, which can be selected from under the File menu. Type in at least some part of the downloaded file's name and let the Finder do the finding for you!
You can also go directly to an FTP site and browse. This is very efficient if you know the file(s) for which you're looking. A link allowing you to browse the archive is usually available on the home page of each FTP web site.
Now I wish this was all there was to know about FTP, but it's not quite that easy. In order to facilitate the economical transfer of FTP files along the Internet, FTP files are usually encoded and compressed. Let's discuss this next.
Retrieving Encoded and Compressed Files
Many of the files in FTP archives are binary files, i.e., application software. They can be downloaded, but they are typically binhexed (encoded) and compressed (made smaller). They are compressed (more commonly referred to as "stuffed" or "zipped") so they download faster, but...why are they encoded?
Why Are Files Encoded?
The Internet is a network that was originally designed for sending text messages between computers. Text messages need only 7-bits of data, so many internet gateways are 7-bits wide by default. Most non-text files that we use are 8-bits wide. If 8-bit wide files are sent through the internet, they can lose 1/8th of their content and be rendered unusable. It's a bit like sending a big truck through a small tunnel. There are ways to perform a 'binary' transfer via the Internet which forces the file to be sent through an 8-bit wide gateway (a bigger tunnel), but the most common way to get around this bit-width problem is to encode the 8-bit wide file into a 7-bit wide format (actually a text format). This process will actually make the file bigger in file-length.
For Mac users, BinHex is the standard 7-bit encoded format because it preserves the Mac file structure. BinHex file names usually have a '.hqx' suffix. UUencoding (UU stands for Unix-to-Unix) is another 7-bit encoding method, but it only encodes part (the data fork) of a Mac file. UUencoding is common for files that are not platform-specific such as graphics files. UUencoded files usually have a '.uu' or '.uue' filename suffix.
So, what do we do about these issues? Again our trusty helper applications (remember helper applications?) come to the rescue! They should (don't you wish you had a nickel for every should you've ever been promised?) automatically recognize when a downloaded file is encoded by looking at its file extension (Mac= .hqx, PC=.exe) and that it is compressed (Mac= .sit, PC= .zip) and perform the proper operation(s) on the file to make it usable. If Netscape does not automatically perform these operations, you will need to run the proper translation software yourself.
The most popular programs for this
procedure are StuffIt Expander (on the Mac) and WinZip (on the PC). A
copy of StuffIt Expander for Macintosh should be located on each lab
computer on campus and WinZip or StuffIt Expander for Windows on
every PC. If you are using a machine which does not have StuffIt, you
will need to get a copy to complete this activity. You can go
directly to the manufacturer, Aladdin
Systems, Inc. or
WinZip.
Click the button or text link below to go to the Stuffit Expander
download page. There will be more instructions available when you get
there.
If you need to do the file translation manually, locate the file you just downloaded (in our example, it probably has a filename such as "gradebook.sit.hqx" or "gradekeeper.hqx") and drag it onto your copy of StuffIt Expander. This "drag-and-drop" procedure should start StuffIt, which will then automatically decode and unstuff the file.
Some Choice FTP Sites
There are too many FTP sites to recount them all here, but a few are: Download.com, Shareware.com, Jumbo.com, Tucows.com, Pure-mac.com, Oldapps.com, and VersionTracker.com.
Conclusion
I hope that this lesson has made FTP a little less daunting for you. There's a lot of fun to be had in FTP sites. You're bound to see mention of lots of FTP files as you peruse the 'Net, so it makes sense to know how to get them.
We'll learn about uploading via FTP in another lesson.
Happy FTPing!
Internet Lessons version 1.8. Copyright of lessons (C) 2007 by Joseph A. Erickson, All Rights Reserved. Permission Granted for Individual Usage.
If you plan to distribute multiple copies of this work, please contact the author.
