Phol 470

The Internet - Web resources

The INTERNET connects a large portion of current computers and has the potential of connecting every computer in the world. Hardware-wise this is facilitated by a number of things,

a network card in your computer

which has a unique number, and an assigned standard format address ( the IP address such as 129.22.122.36)
This address is usually converted/translated into names, which are more easily remembered by name servers
(such as 129.22.4.3, one of the CWRU name servers = ns2.cwru.edu)

or a modem and a network access provider (which lets you use your phone to connect to a computer with internet access/ and the needed software, and which assigns your computer and address for every session)
a fixed protocol for the communication between different computers (TCP/IP).

which you have already encountered in the session on networks. The term Internet now refers to the fact that single independent computers, and wide or local networks are connected worldwide. Connections are unregulated and not a hierarchical structure, which was actually intended by its designers (academia and the military at the height of the cold war). The physical computer connections (and the flow of information) can be best compared with (cars on ) the street system. Even if one street/computer connection is down, the information will find a different way to the target computer.

With the vast numbers of computers connected, several problems existed: how to provide access to information to specific users / or basically unknown people/computers, while keeping local security. Further, from a user's perspective: how to find the information one desires or which is available. Previous attempts to provide open access to anonymous users included archie and gopher, but these required central catalogs/directories and were often lagging completeness, further inconvenient to use.

The World Wide Web (W3)

The term Web refers to a newer way, about five year old, of providing access to local information or resources on a computer to outside users/the world. The heart of the web is the http-protocol. It allows anonymous users/outside computers access to selected information without specific access control, accounts or passwords. Specific server software (http-server) on a computer is activated at every request for connection, and sends the desired information over to the client, the requesting computer.. Basically every computer connected to the net can be a web-server, although most standard PC- or Mac operating systems don't come with this software.

Information/documents are written in a simple text-based language called HTML (hyper text markup language). Markup refers to several features, such as the capability of formatting, and to include headers, graphics, other resources, and specific instructions for the software. The html documents reside in specific locations on the server, thus separating local (protected) files from outside access.

The counter part to the server software, the client-software used to find and access on the Internet i.e connected server computers worldwide, are specialized programs called Web browsers. These programs display the information they receive in html. They are also able to access other resources and services (such as ftp, newsgroups etc). Browsers further include specialized tools, such as html-editors to generate your own documents, or separate newsreaders, e-mail editors so that you never have to leave the programs. Further, Plugins can be installed/are available, which enhance the capabilities of the browsers, such as sound, video-player(quick time), special graphics file displayer or general multimedia enhancement programs (shockwave etc.), Adobe acrobat plugin to view and print portable data files (PDF) , virtual reality display, or even more specialized (such as those for displaying 3d-images of protein structures, Chime). Commonly used programs are Netscape Navigator, Microsoft Explorer , and some other. Here you will use Microsoft Explorer (unfortunately). The success of the Web stems in part from the graphics and sound capabilities, and the ease of preparing webpages in html format. The real strength, however, is the internet appropriate design of the locations field (URL) used to connect and the possibilities to include these as reference points in the document itself. Thus, accessing other computers/web pages is reduced to occasionally typing the web-page location, or (most frequently) by just clicking a mouse button on a highlighted word, a link. Thus "surfing the web" means finding your way from any selected starting points from web-page to web-page/ computer to computer, without any limits in directions (creating a net of interconnected points as individual crossover points on a spider web).

Web Locations (URL) have usually the following, common format:

http://www.xxx.xxx/

such as http://www.cwru.edu/

or http://www.microsoft.com/

Note: most browsers allow you to type into the location window, and they also per default fill in http:// for you.
Some location differ in constructions, such as

http://physiology.cwru.edu

Other resources (than http, the server programs which allows the access of the webbrowser as a client) can be chosen by the first string such as:

ftp:/ accesses an anonymous ftp site

gopher:// access a gopher site

mailto: will call up the mail editor and send your message

file:/ to retrieve/display a local (html) file.

Links: references to other files/location appear highlighted in the text , usually in blue and/or underlined), or red / in an altered color if you followed that link before. These words/links can be clicked, and connect to the respective documents. Graphics in blue are also clickable/ links. More recently, many graphic items are also links, and the cursor changes shape if you are on top of them.

Bookmarks let you quickly jump to specific locations in a longer document, they look identical to other links. Most Web browsers also have bookmarks /Favorites in Explorer, with predefined places of interest, and the capability of saving your own selected locations for later use.

Search Engines: The major advantage of the Internet is also its greatest problem: the unregulated wealth of Information. Thus, finding the information one is looking for is not straightforward, despite the ease of access of remote computers. Thus over the years, people and companies have developed several programs to locate information on the net. These programs are called search engines. (You will find some of these if you click on Search in Explorer (or Netscape) or some of them on my home page). However, as the size of the documents on the web has exploded over the years, some engines have problems keeping their records up to date, and give you outdated links/ and an rather incomplete picture of the information available.

Examples: (there are many more)

Yahoo. One of the best ways to find information due to its directory or index structure. Keyword search also possible.

Hotbot, Altavista: Search of basically all words contained in the Web pages of the world, thus most complete contents.

C/NETS shareware: find (and download) programs in an index of public domain software, but not complete.

Magellan: search of checked, indexed and rated sites

Also, various sites keep versions of white/yellow pages /telephone directories, which are searchable. (www.bigfoot.com , www.whowhere.com)

See the Appendix/following pages for further links and the Exercises