This chapter is from the book
This chapter is from the book
This chapter is from the book
WWW: World Wide Web
The World Wide Web (WWW, W3, or the Web) provides a unified, interconnected interface to the vast amount of information stored on computers around the world. The idea that created the World Wide Web came from the mind of Tim Berners-Lee of the European Particle Physics Laboratory (CERN) in response to a need to improve communications throughout the High Energy Physics community. The first generation was a notebook program named Enquire, short for "Enquire Within Upon Everything" (the name of a book from his childhood), that he created in 1980 and that provided for links to be made between named nodes. It was not until 1989 that the concept was proposed as a global hypertext project to be known as the World Wide Web. In 1990 Berners-Lee wrote a proposal for a HyperText project, which eventually produced HTML, HyperText Markup Language, the common language of the Web. The World Wide Web program became available on the Internet in the summer of 1991. By designing the tools to work with existing protocols, such as FTP and gopher, the researchers who created the Web created a system that is generally useful for many types of information and across various types of hardware and operating systems.
The WWW is another example of the client/server paradigm. You use a WWW client application, or browser, to retrieve/display information stored on a server that may be located anywhere on your local network or the Internet. WWW clients can interact with many types of servers; for example, you can use a WWW client to contact a remote FTP server (page 408) and display the list of files it offers for anonymous FTP (page 380). Most commonly you use a WWW client to contact a WWW server, which offers support for the special features of the World Wide Web that are described in the remainder of this chapter.
The power of the Web is in its use of hypertext, a way to navigate through information by following cross-references (called links) from one piece of information to another. To use the Web effectively, you need to be able to run interactive network applications. The first GUI for browsing the Web was a tool named Mosaic, released in February 1993. It was designed at the National Center for Supercomputer Applications at the University of Illinois and sparked a dramatic increase in the number of users of the World Wide Web. Marc Andreessen, who participated in the Mosaic project at the University of Illinois, later cofounded Netscape Communications with the founder of Silicon Graphics, Jim Clark. They created Netscape Navigator, a Web client program that was designed to perform better and support more features than the Mosaic browser. Netscape Navigator has enjoyed immense success and has become a popular choice for users exploring the World Wide Web. Important for GNU/Linux users is fact that from the beginning, Netscape has provided versions of its tools that run on GNU/Linux. Also, Netscape created Mozilla (mozilla.org) as an open-source browser project.
Mozilla and the Netscape Navigator24 provide GUIs that allow you to listen to sounds, watch Web events or live news reports, and display pictures as well as text, giving you access to hypermedia. A picture on your screen may be a link to more detailed, nonverbal information, such as a copy of the same picture at a higher resolution or a short animation. When you run Mozilla or Netscape on a system that is equipped for audio, you can to listen to audio clips that have been linked to from a document.
URL: Uniform Resource Locator
Consider the URL http://www.w3.org/pub/WWW. The first component in the URL indicates the type of resource, in this case, http (HTTP—HyperText Transfer Protocol). Other valid resource names, such as https (HTTPS—secure HTTP), and ftp (FTP—File Transfer Protocol), represent information available on the Web, using other protocols. Next comes a colon and double slash (: // ). Frequently the http:// string is omitted from a URL in print, as you seldom need to enter them to get to the URL. Following this is the full name of the host that acts as the server for the information (www.w3.org). The rest of the URL is a relative pathname to the file that contains the information (pub/WWW). Enter a URL in the location bar text box of a Web browser, and the Web server returns the page, frequently an HTML (page 1472) file, pointed to by this URL.
By convention many sites identify their WWW servers by prefixing a host or domain name with www . For example, you can reach the Web server at the New Jersey Institute of Technology at www.njit.edu . When you use a browser to explore the World Wide Web, you may never need to use a URL directly. However, as more information is published in hypertext form, you cannot help but find URLs everywhere—not just online in mail messages and Usenet articles but also in newspapers, advertisements, and product labels.
Browsers
You might want to consider using Web browsers other than Netscape with your GNU/Linux system. If you do not use the X Window System, try a text browser, such as lynx or links. Mozilla (www.mozilla.org) is the open-source counterpart to Netscape. Mozilla was first released in March 1998 and was based on Netscape 4 code. Since that time Mozilla has been under development by employees of Netscape (now a division of AOL), Red Hat, other companies, and contributors from the community and has released its version 1.0. KDE offers Konqueror, an all-purpose file manager and Web browser (page 286). Other browsers include Galeon (galeon.sourceforge.net), Opera (www.opera.com), BrowseX (browsex.com), and SkipStone (muhri.net/skipstone). Although each Web browser is unique, they all allow you to move about the Internet, viewing HTML documents, listening to sounds, and retrieving files.
Search Engine
Search engine is a name that applies to a group of hardware and software tools that help you find World Wide Web sites that have the specific information you are looking for. A search engine relies on a database of information collected by a Web crawler, a program that regularly looks through the millions of pages that make up the World Wide Web. A search engine must also have a way of collating the information the Web crawler collects so that you can access it quickly, easily, and in a manner that makes it most useful to you. This part of the search engine, called an index, allows you to search for a word, a group of words, or a concept and returns the URLs of Web pages that pertain to what you are searching for.
Many different types of search engines are on the Internet. Each type of search engine has its own set of strengths and weaknesses. You can obtain a partial list of search engines by going to home.netscape.com/escapes/internet_search.html or by clicking the Search button on the Netscape or Mozilla menubar.
Downloading a File
You can use Mozilla, Netscape, or another browser to look at and download a file from an FTP or HTML site. Suppose you enter ftp://ibiblio.org/Linux in the text box of the location bar and press RETURN. After seeing the initial set of directories, click pub (many sites give their public directory this name). You can then click any of the directories (try Linux) to view the available files. Following this example you will find directories named with the classifications of software, documentation, distributions, and more. Each contains a wealth of directories with more directories and files that you can download. You will also find html files that display a graphical interface to the directories. When you click a file that is intended to be downloaded, Mozilla or Netscape opens a window asking you where to put the file on your system. Refer to "Installing and Removing Software" on page 926 for information about unpacking and installing the software that you download.
TIP: When a File is Downloaded to Your Screen (and You See Garbage)
If garbage appears on your screen, the file is being downloaded to your screen. Click Stop and then Back: You should be back where you started. This time hold the SHIFT key down while you click the file you want: This tells Mozilla/Netscape to download the file instead of trying to display it.