Last updated: 4/20/2000
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Update on 4/20 Class

During the class of 4/20, we went through this Agenda, except for items VI and VII.

Computers, the Internet, and Society
Agenda for Class 8
4/20/2000

1. Announcements
   1. The Final Exam is next week, April 27 during the regular class time. The Final will be cumulative.
   2. Online grade reports are working - see me if you need to be reminded of your password for this system
   3. Do sign-in.
   4. Essay 2: This essay should have the same length and form as Essay 1 (five pages with header, title, introduction, body and conclusion). For the topic, pick either The Lexus and the Olive Tree or Release 2.1, and choose any two of the topics from the Internet Issues handout. Integrate these two topics into a single subject for your essay, using material from the book you chose. Be sure to tell me in the header at the beginning of your essay, which book and which topics you are writing on.
   5. In the Essays and postings, some have been writing that there is no way to protect children from pornography on the Internet, or to safeguard your personal information. If this subject comes up on the Final, I will expect you to at least acknowledge the safeguards in Release 2.1.
2. Internet News Stories
   1. Canadian authorities made an arrest in the Denial of Service (DOS) attack on CNN.com on February 8. (The series of attacks started on February 7 against Yahoo.) The arrest was of a Montreal high school student known online as "Mafiaboy", although as a minor his real name cannot be released under Canadian law. In online chat rooms, he (assumed to be the same person although others use the same online name) had bragged about making the attacks, although several others had also, and he had also asked for advice about whom to attack next. Another part of the evidence comes from files left on the co-opted computers that actually made the attacks. There was speculation about more arrests, and some debate about whether the attackers were organized (a group called TNT might be involved) or copycats. Some commentators said that too much organization (presumably taking over the computers that directly attacked the target sites) was required for copycats to be able to follow on so soon. The potential penalty is 2 years jail time and a fine of $1,000. The target sites have said that their losses of advertising income were minimal, while some market research firms have put the losses at hundreds of millions of dollars. This discrepancy suggests to some that the target sites either do not know how much they lost, or are trying to conceal their losses from investors.
   2. Wireless networks are being installed on college campuses, for use by students and faculty. The networks work like small cellular systems, with user connected computers transferring their communications to the nearest antenna, although speeds are far higher than cellular modems allow, 1.6 MBps compared to 14.4 KBps for cellular, but less than wired networks at 10 MBps and moving to 100 MBps. Primary networking targets are office buildings, dormitories and classrooms. Such networks are expected to proliferate quickly, for use at work, home, and even public places such as airports. By saving on installation costs, wireless networks can cut costs.
   3. Several companies are making "smart tools". Examples are constant-speed electric drills, stud-finders that are able to detect wood, nails, pipes and wiring, and distance measurers that are able to remember the dimensions of a room after you measure it, and calculate the area of a wall or the volume of a room.
   4. In the penalty phase of the Microsoft case (Microsoft has already been found guilty of misusing their monopoly powers), the states have so far been unable to agree on a penalty.
3. Finishing up
   1. From the Assignment Schedule: I will allow you to redo assignments and turn in missing work after the course is over. Such work will not appear in your regular grade, but it will be taken into account in a Change of Grade, and it will eventually appear on your official transcript. The University will allow me to file a Change of Grade up to one calendar year after the end of the semester in which you took the course. For this course, that is through the end of the Winter 2001 semester. I will not accept major assignments during the last month of this period. If you are redoing an assignment, the original assignment with my comments and grades must be turned in along with the redone assignment.
   2. To count in the regular course grade, work must be in by the day of the Final Exam, April 27. Work turned in after that will show up in a Change of Grade.
4. Internet - finishing this handout
   1. What can we expect from the Internet in the near future?
      1. Continued rapid growth - doubling every year or so
      2. Increased speed - cable modems, Internet 2
      3. More services, e.g. movies
      4. It is not clear that security will be improved, although that could easily be done - there is little demand for it
      5. Decreased costs for connection ("Internet appliances" such as iNet)
      6. Making the web smarter - XML or Extensible Markup Language. This is a system for describing data so that it can be handled as the number ordered or currency, etc. This wil mean that web pages can incorporate data types, much like a database. Since this will make the web more useful, it should also make the web even more popular.
   2. Convergence
      1. Merging of several functions into one device. Example in class.
   3. Communications power shifting to the individual
      1. Can more easily choose between stores
      2. Can search for stores
      3. Can send messages to anyone connected to the Internet - also many services to find people
      4. Can easily and cheaply set up a web server to sell, inform, etc.
      5. There is no licensing authority
      6. There is no claim here that the Internet is a perfect communications medium for the individual. the claim is only that it gives more power to the individual, compared to earlier forms.
         1. For example, setting up a web server can cost $1,000 or less. Setting up a "brick and mortar" communications medium such as a newspaper, a TV station or a radio station costs $1,000,000 or more.
         2. Some people claim that big business will find a way to take over and control the Internet. This has been tried and it failed. Customers will flee an ISP that does not give full access, for example. Since it is cheap and easy to become a small ISP, if this preference continues, big ISPs will have trouble if they try to restrict access.
5. Update on web pages
   1. Browser cache
   2. Cache = local special storage, in this case, for web pages you have visited
   3. Maintained by web browser, separate sections on hard drive and in working memory
   4. When Browser requests a file from server, by means of a header, it asks the Browser to return the current date of the file. If the date of the file in the cache is the same as the date of the file on the server, the Browser provides a faster response and reduces the load on the server by displaying the copy in the cache. Normally this works pretty well, but the date comparison (apparently) does not include time. So if you view a page from the server in the morning and change it on the server in the afternoon, and then view it the same day, your Browser will still display the older cache copy.
   5. There are solutions. Each Browser has a method for overriding the cache and forcing an update from the web server.
      1. Netscape - <Shift>Reload
      2. Internet Explorer - Reload or <F5>
      3. You can also clear the cache in both Browsers to force going tot he server. Be sure to clear both the disk and RAM cache.
      4. If you normally work on a quickly-changing web site, you might consider zeroing the memory devoted to cache storage. Again, be sure to zero both the disk and RAM cache.
   6. How the web handles different file types
      1. When the web server receives a URL specifying a certain file, for most file types in most folders, the web server simply returns the file to the Browser, letting the Browser figure out how to handle it. Exceptions: executable files (*.exe) in specified directories (e.g. cgi-bin, cgi-win) are executed on the server with an output file returned to the Browser. "Server-side script files" (e.g. Perl, *.pl) in any folder are also executed on the server with an output file returned to the Browser. These are the mechanism for "interactivity" - taking input from the user via a form, processing that information on the server, and returning a customized file to the Browser.
      2. Web Browsers handle certain file types internally. These types are HTML, GIF, JPEG, PNG and a few other minor types. All of these "automatic" types are displayed on the screen by the Browser.
      3. For many other file types, the Browser may have been configured to use "plug-in" or "helper" applications to handle the file type. Many of these applications are proprietary, and may even be pre-configured in the Browser. Usually the Browser plug-in can be downloaded for free, as a means to building traffic and therefore sales for the server-side software. Examples:
         1. *.pdf (portable document format). Use Adobe Acrobat Reader to display the file on the screen.
         2. *.rpm. Use RealPlayer for this multimedia (sound, graphics and video) file.
         3. *.mov. Use QuickTime movie player
         4. *.wav. Use Windows sound player
      4. Many desktop applications will, by default, install themselves as viewers for their file types. Examples are Word (*.doc), Excel (*.xls), Access (*.mdb) and PowerPoint (*.ppt). When one of these file types is returned, the Browser starts the corresponding application to display the file. These files are not displayed in-line in the Browser window, but as separate windows. There may be a choice between saving to disk and displaying the file.
      5. The Browser can also be configured to execute scripts (e.g. javascript, java, vbscript) embedded within an HTML file.
      6. If the file type is not one of 2, 3, 4, 5 or 6, then the Browser will ask the user what to do with the file. The normal option is to save it to disk for later offline processing.
6. Finishing off the forms of computer information
7. Windows common elements - go to handout

9. Ping and TraceRt - handout
10. WS_FTP - handout