Chapter 7 Commerical Information Services Who are they 4 biggest are Prodigy, America OnLine (AOL), compuserve, and Microsoft network What are they They are like a very large host computer supporting very large data base of information with the capability to accomodate many terminals connected through telephone lines and modems. What services do they provide Travel information, access to on-line airline travel reservations, on-line magazines that you can browse, electronic shopping malls, stock quotes, online technical support for software and hardware, chat rooms for on-line conversations with other service users on a particular subject or celebrities, electronic mail capability, and internet access. Some of these capabilities are provided exclusively by the information service and some are available to all through the Internet. Why use an information service Relatively easy, inexpensive way to gain access to information and the internet if not supplied for free by your school. Most services provide easy to use menus and user interfaces, to help you get the information you desire. How much do they cost Basic user fee of $10 or so per month. Extra fees for premium services and for connect time beyond the time alloted in the basic fee. How to subscribe Get a startup kit - may be mailed to you or in a magazine. Comes with a disk that has communications software for the service and a temporary id and password. Install the communciations software on your computer, select a local access number from the ones provided by your software, and dial up and connect to the information service's computer using your modem. What is the Internet? It started in the 1960s as a project of the Advanced Research Project Agency (ARPA). It was originally known as ARPANET. The goal was to create a secure network of computers that could withstand a nuclear attack. The network should be able to function even if one or more computers was knocked out of service. This would allow personnel at one site to use a computer at another site if their computer was unavailable. It began with 4 computer networks in the US in 1969. Today the internet is a network of over 2 million computer networks worldwide. Each network is called a site. Major sites are connected together by special high speed communicatons links called the internet backbone. Each major site provides access to the internet to the computers in its own local area network. A major site will also be connected to several other sites (computer networks) in its geographical area and provide internet access to these other sites. For example, in the Philadelphia area UPenn is a major site. It provides internet service to the network of campus computers wired into it (faculty offices, labs, dormitory rooms) and connected by telephone lines (in faculty and student homes). As a major site, UPenn has links to computer networks at all the other colleges in the Philadelphia area. They are connected to the internet backbone through UPenn. A message from a Temple student's home computer travels over phone lines to the Temple network. If it is intended for someone at Temple, it is routed to that person. Otehrwise, it is sent over the link to UPenn and travels over the internet backbone to the closest major site to where it is going. It then travels over the link from that major site to its destination computer network and user account on that network. An internet address indicates quite a bit about the user. Koffman@falcon.cis.temple.edu user id (Koffman) - machine name (represented by @falcon.cis) - domain name edu - education gov - government (non-military) mil - military org - other organizations (professional society, library) com - commercial net - network resources At temple, we have other common addresses such as user-id@thunder.ocis.temple.edu You should all get a user account on nimbus before your internet lab (week of October 29). What kind of information is available on the internet - almost anything - much more than is available through a commercial service. You can access any information that is publicly available on ANY computer connected to the network. However, there is no user-friendly menu to help you navigate through it or special services (like celebrity chat rooms) that are available on the commercial services like compuserve. Services provided on the internet 1. Send electronic mail EMail - need electronic mail package on your computer. When you log into nimbus or thunder, you use the mail package on that computer. It is menu driven and reasonably user friendly. There are also packages you can get for you own computer to manage and send mail. 2. Find and view information on a variety of topics----World wide web ----Connects you to on-line museums such as provided by the Louvre in Paris, online libraries, companies, newspapers, magazines, shopping malls. Need a web browser such as netscape, mosaic, winweb, or lynx. At Temple, we use netscape and lynx (text only). 3. Download files of programs, text, graphics, music, animation, videos --- FTP (File transfer protocol)---- Use FTP software, a web browser, or Gopher. 4. Run programs on a remote host, play interactive games maintained on a remote host, use library card catalogues ---- Telnet --- Telnet client software. 5. Search for documents, databases, library card catalogues ----- Gopher -- Gopher client software, web browser 6. Participate in on-line discussion groups ----- Usenet ---- Newsreader software. eMail allows you to send mail messages to anyone who has an account at any computer on the internet. Side benefit to eMail - my daughter (27, teacher) met a young man from Chicago at a friend's house. They communicated by eMail for a couple of months - got to know each other through eMail - decided to meet again in Chicago -- young man is moving to Philadelphia next week. World Wide Web (or Web). Information covers every topic and is passed in multimedia format with text, graphics, film clips, music, etc. WWW is a "wide-area hypermedia information retrieval initiative to give universal access to a large universe of documents." Consists of a collection of Web pages that provide information on a patrticular topic. In addition, each Web page might include links or pointers to one or more Web pages to access more information on that topic or a related topic stored at that computer or any other computer on the internet. To use the web, an internet site must set up a web server and format its information into pages using a HTML (Hyper Text Markup Language) editor. You can also use word processors like Word to create a document and then save it in HTML format. Web users can compose their own home pages (HTML documents ) which are stored on their web server. When you run special web browser software (netscape, mosaic) from your local computer, you first access the home page of your web server. From there you can branch out to any other site. When you read a web page, you will see some text that is underlined and in color. This represents a link to another web page. You use your mouse to move a cursor to that portion of the page and your cursor becomes a hand. Click the mouse and you will download the new web page to your web server (the computer you are connected to) so that you can read it. If there is any graphics, animation, etc. that gets downloaded to. You can save web pages on your local hard disk or print them out. Some sites provide software for your PC that you can download. For example, Microsoft provides software that you can add to Word to enable it to compose web pages more easily. You download that software by clicking on text which describes it and then install it on your own computer. There are usually installation instructions on the home page that has the link to the software. Each web page has a unique address called a uniform resource locator (URL). To access a web page you either follow a link (already described) or type in a URL in the box marked Location: on the web page you are currently viewing and then go (click on icon Go) to that page. You can go backwards (click on icon Back) to return to a previous page. A URL is like an email address. Each URL starts with http:// which identifies it as a web page (hypertext transfer protocol - the protocol (electronic mechanism) used to transfer hypertext documents from site to site. http://www. temple.edu http://www.temple.cis.joda/koffman~ http://www.microsoft.com If you have a nimbus or thunder account, you can use any terminal (or your computer as a dumb terminal) to browse the world wide web using Lynx (text only - no graphics). Just type in Lynx at the prompt and you are ready to go. You get Temple's hme page. To access any other site, type G for Go. It will prompt you for the URL at that site. You can also type S (for Search), and it will prompt you for search keywords. When you respond it will return with a list of URL's that match the keywords. YOu can click on any of them to begin your journey. Downloading software - can do this through the web or using FTP (File transfer protocol). You need FTP software which connects your computer to a remote host computer called an FTP server. Your computer then becomes part of that server's network. You can browse through a list of software available and then download software to your computer, install it, and run it on your computer. Or you can download data files. Since you don't have an account on the host computer, you log in as an anonymous user (user id is anonymous). Anonymous FTP on a server means that the service allows anyone to log in as an anonymous user and download publicly available software. Telnet is an internet service that establishes a computer between your computer and a remote host. Telnet software allows you to log in to another computer from your computer and access that computer, run its software, or process its data files. You need to have an account with password for the host computer you connect to. For example, from Thunder, you type telnet new computer, and you get a log in prompt from new computer. From that point on you are using new computer as your host, not thunder. You normally type exit to return back to your original host computer. Gopher is a pre-WWW menu-driven internet service to help you locate information at remote sites. To use Gopher, you need to connect to a Gopher server using Gopher software at your site. Once at a Gopher server, you get a menu of options and can obtain a list of topics available (folders). You can open each folder to get a list of specific internet documents on that subject. These documents may be stored at the Gopher server or any other Gopher site (site connected to a Gopher server). Like the WWW except it is menu-driven. The menus provide links between the documents. The links are not in the documents as they are in the WWW. Usenet is an internet facility that allows net users to set up discussion groups on any subject. A discussion group is called a newsgroup and you can easily set up one on your computer (thunder or nimbus) providing it has usenet software (Temple uses tin, available on UNIX machines). Interested people send a special message to the computer that is the host for the newsgroup in order to subscribe to the newsgroup. You can access the newsgroup bulletin board and post a message (called an article). Others can read your message and post responses to it. The responses are then availabe for others to read and respond to. A series of messages on a particular topic is called a thread. Sometimes newsgroups are set up through eMail so that each posting is sent via eMail to all members of the newsgroup rather than being stored on the newsgroup host computer or bulletin board. Etiquette for using newsgroups: Use conventions to avoid misunderstandings: identify jokes by smiley symbols such as :-) - sarcasm by ;-). provide a portion of the originla message in your reply when you resond to a message so other readers can follow the thread. Avoid flames (nasty message to a member you disagree with) or shouting (all caps in a message). If you have a personal message in response to something you've read, send it by eMail - don't post it to the entire newsgroup - could be embarassing to you or upsetting to other newsgroup members who have to waste their time reading it. Elliot Koffman, Professor CIS Department Temple University