Give short answers (on paper) for the following questions on materials covered in the lectures. Note: The answers to some of the questions below were exclusively covered in the class (i.e. not in the textbook).

a. What is the difference between ``local'' and ``remote'' management of Email?
b. What is the function of SMTP in the mail delivery process?
c. What are the main parts in a Univeral Resource Locator?
d. Explain the function of DNS (the Domain Name Service on the Internet)?
e. How many DNS requests are necessary to figure out the IP address of www.cs.uri.edu?
f. Can you explain what it means for a data delivery mechanism to be ``store-and-forward''?
g. Explain the difference between an ``absolute'' and a ``relative'' filename.
h. If your current directory is /cs/www/html then what would be the relative filename for /cs/www/html/temp/cs101b1/smith/Home.html?
i. Describe five possible reasons that may result in an email message to ``bounce back'' to its sender.
j. Describe five possible errors that may occur upon trying to fetch the contents of a URL using a Web browser (e.g. Netscape).
k. Why is it necessary to assign servers to specific ``standard'' port numbers (e.g. the HTTP server is at port 80)?

In this problem you will get a taste of the basic editing capabilities of Emacs.(1) By the end of it, I hope that you will feel comfortable using Emacs as an editor. Your familiarity with Emacs is extremely important for you to be able to keep up with upcoming homeworks. Actually, your ability to create and edit files is crucial for the completion of other problems in this homework (namely, the creation of your home page). There is much more to emacs than what is described here. Some of these features will be discussed in the discussion sections.

Before we delve into the details of Emacs, it is important to note that Emacs allows two methods for invoking its commands. The first is a ``point-and-click'' interface based on the X Windows GUI, whereby the user could select various commands by selecting options using various menus, etc. The second is a ``character'' interface, whereby the user could select various commands simply by typing on the keyboard (i.e. without having to use the mouse). In this problem, we will use the ``character-based'' interface. If you would like to try the ``point-and-click'' interface, you are welcome to try it out!

Using Emacs' ``character-based'' interface for invoking commands requires frequent uses of the ``control'' and the ``escape'' keys on the keyboard. The symbol CTRL- is used to indicate the use of the ``control'' key. For example, CTRL-A means press the ``control'' key and then (while still pressing it), press the character ``A''. Also, CTRL-X1 means press the ``control'' key and then (while still pressing it), press the character ``X'' and then (after releasing the ``control'' key) press the character ``1''. The sequence ESC- means pressing and releasing the ``Escape'' key. For example ESC-v means press the ``Escape'' key, release it and then press the character ``v''.

a. Start an Emacs session by typing emacs at the UNIX prompt.
b. From within Emacs, create a file called foo using the CTRL-X CTRL-F command. In this file start typing a short essay (say) 10 lines about anything you want. Make sure you practice saving your essay every now and then using the CTRL-X CTRL-S command. Also, if you want to check the spelling of a particular word from within emacs, position the cursor on that word and then type ESC-xspell-word followed by the ``return'' key. Get out of Emacs using the CTRL-X CTRL-C command. Remember to save the files you are editing before getting out. If you don't, Emacs will ask you if you want to save your files before getting out.. Remember, if you don't save it, you loose it!
c. Start another session on Emacs (same as step a.) and retrieve the contents of the file foo using the CTRL-X CTRL-F command. Did you find your essay intact? (It'd better be!) If you need to make changes go ahead...
d. Without leaving Emacs, create a new file using the CTRL-X CTRL-F command. Call the new file foobar. In this file describe in few words what each of the following commands does: CTRL-X CTRL-F, CTRL-P, CTRL-N, CTRL-B, CTRL-F, CTRL-V, ESC-V, CTRL-L, CTRL-D, CTRL-K, CTRL-Y, CTRL-T CTRL-X CTRL-C, ESC->, and ESC-<.
e. Without leaving Emacs, type CTRL-Xb.(2) Emacs will ask you whether you want to switch buffers. If you press the ``return'' key, Emacs will go back to editing the foo file. So, go ahead and press the ``return'' key to switch buffers.
f. Repeat step e. to go back to editing foobar. Now, add to foobar a description of what you think CTRL-Xb is doing.
g. Get out of Emacs using the CTRL-X CTRL-C command.
h. From the Unix prompt make sure that the files you created above (namely ``foo'' and ``foobar'') are present in your home directory. To do so, type ls -la from the Unix prompt. Hand-in a printout of both of these files as a solution to this problem. Recall that the lpr command we introduced in homework 2 could be used to print these files.

The grade for this problem will depend on how much work you put in making your home page elegant and interesting to others. You will need to go through the following steps:

• Start emacs and create a new file /cs/www/html/temp/cs101b1/login/Home.html.
• In that file you may write whatever information you want others to know about you. For example, your name, address, phone numbers, where you come from, your hobbies, your major, ... etc. A good idea to make your document elegant is to use the HTML formatting instructions that we talked about in class. These are described in a document that you can view on the web (check the supplemental readings page from the course home page).
• In that file you are also required to include few pointers to WWW resources that you have discovered and that you liked (the more the better!). You can do that using the href HTML command described in class.
• Once you finish editing your home page, get out of Emacs. Now, you need to change the permissions on your Home Page so as to make it readable to everybody in the CS cluster. To do so, issue the chmod a+r /cs/www/html/temp/cs101b1/login/Home.html from the UNIX prompt.
• Take a look at your home page using Netscape. To do so, you need to access the class home page, and from there access the ``Student Home Pages'', which is part of the course archives. From there, find your own entry and click on it to get to your page.
• If you find that your Home Page does not look the way you wanted it to be (for example because you mistyped an HTML command), you may want to go back and edit your Home Page by starting Emacs and changing it as you wish.

-- Start a session on TOMUS and answer the following questions:
1. How many library items have the word ``Greco-Roman'' in the title?
2. How many ``computer'' subjects exist under the Library of Congress cataloguing system?
3. Find the titles of all books that have Computer as a subject AND Knuth as an author.
4. Can you locate the textbook of this course? Can you locate the textbook you are using for any other course of yours? Give the name of the library and the call number for any such textbooks.

Note: The solution to this problem is simply a short writeup (i.e. on a piece of paper) with answers to the above 4 questions. For more information about Tomus, check the course supplementary readings.

Created on: 1997.08.01
Updated on: 1997.09.02
Maintainer: Azer Bestavros
            best@cs.bu.edu