{"id":312,"date":"2020-08-18T19:23:47","date_gmt":"2020-08-18T20:23:47","guid":{"rendered":"http:\/\/www.linux-tutorial.info\/?page_id=77"},"modified":"2020-08-22T19:25:16","modified_gmt":"2020-08-22T20:25:16","slug":"this-is-the-page-title-toplevel-147","status":"publish","type":"page","link":"http:\/\/www.linux-tutorial.info\/?page_id=312","title":{"rendered":"Accesing the Web"},"content":{"rendered":"\nAccessing the Web<\/title>\n<p>\nIt was difficult to decide where to put this topic. You can’t have access to the Web without\nnetworking, however, it looses much of it’s impact unless you are using a graphical interface like\n<glossary>X<\/glossary>. Because the Web is a <glossary>network<\/glossary> of machines accessed in a common manner, I figured the networking chapter would be the best place to talk about it. I think this is a good choice since, there are character based programs that do not require X.\n<\/p>\n<p>\nSo what <em>is<\/em> the Web? Well, as I just mentioned, it is a <glossary>network<\/glossary>\nof machines. Not all machines on the Internet are part of the Web, but we can safely say that all machines on the Web are part of the Internet. The Web is the shortened version of World Wide Web, and as its name implies it connects machines all over the world.\n<\/p>\n<question id=\"\" type=\"mc\" text=\"For what the World Wide Web first developed?\" \/>\n<question id=\"\" type=\"mc\" text=\"Where was the World Wide Web invented?\" \/>\n<question id=\"\" type=\"mc\" text=\"When was the World Wide Web invented?\" \/>\n<p>\nCreated in 1989 at the internationally renowned CERN research lab in Switzerland, the Web was\noriginally begun as a means on linking physicists from all over the world. Because it is easy to use and integrate into an existing <glossary>network<\/glossary>, the Web has grown to a community of tens of thousands of sites with millions of users accessing it. With the integration of Web access software, on-line services have opened the Web up to millions of people who couldn’t have used it before.\n<\/p>\n<p>\nWhat the Web really is, is a vast <glossary>network<\/glossary>\nof inter-linked documents, or resources. These resources may be pure text but can include images, sound and even videos. The links between resources are made through the use\nof the concept of <glossary>hypertext<\/glossary>. Now, hypertext is not something new. It has been used for\nyears in on-line help systems, for example, like those in MS-Windows’ programs. Certain words or phrases are presented in a different format (often a different color or maybe underlined). These\nwords or phrases are linked to other resources. When you click on them, the resource that is linked\nis called up. This resource could be the next page, a graphics image, or even video.\n<\/p>\n<question id=\"\" type=\"mc\" text=\"What protocol is used to load pages from the web?\" \/>\n<p>\nResources are loaded from their source by means of the hypertext transfer <glossary>protocol<\/glossary>,\n <glossary>HTTP<\/glossary>.\nIn principle, this is very much like <glossary>FTP<\/glossary>,\nin that resources are files that are transferred to the requesting site. It is then up to the\nrequesting <glossary>application<\/glossary> to make use of that resource, such as display and image\nor playing an animation. In many cases, files are actually retrieved using ftp instead of HTTP and\nthe application simply saves the file on the local machine.\n<\/p>\n<p>\nThe <glossary>application<\/glossary>\nthat is used to access the Web is called a Web browser. Web resources are provided by <em>Web\nServers<\/em>. A Web Servers is simply a machine running the <glossary>HTTP<\/glossary> daemon:\n<command>httpd<\/command>.\nLike other <glossary>network<\/glossary> daemons, httpd receives requests from a Web\n<glossary>client<\/glossary> (such as Mozilla or Konqueror) and sends it the requested resource.\n<\/p>\n<p>\nLike the <command>ftp<\/command>\n<glossary>daemon<\/glossary>, <command>httpd<\/command>, is a relatively secure means of allowing anonymous\naccess to your system. You can define a root directory, which, like ftp, prevents users from going “above” the defined root directory. Access to files or directories can be defined on machine basis and you can even provided password control over files.\n<\/p>\n<question id=\"\" type=\"mc\" text=\"What is HTTP?\" \/>\n<p>\nWhen <command>httpd<\/command> starts, it reads its configuration files and begins listening for requests from a\ndocument viewer (one that uses the <glossary>HTTP<\/glossary> protocol). When a document is\nrequested, httpd checks for the file relative to the <glossary>DocumentRoot<\/glossary> (defined in srm.conf).\n<\/p>\n<question id=\"\" type=\"mc\" text=\"Pages in the World Wide Web a references using what?\" \/>\n<concept id=\"\" description=\"Pages in the World Wide Web are referenced using a Uniform Resource Locator (URL).\" \/>\n<question id=\"\" type=\"mc\" text=\"What is the language typically used to write web pages?\" \/>\n<question id=\"\" type=\"mc\" text=\"What is HTML?\" \/>\n<p>\nWeb pages are written in the <glossary>Hypertext Markup Language<\/glossary> (HTML). This is “plain-text” file that\ncan be edited by any editor, like vi. Recently, as a result of the increasing popularity of the Web,\ndozens, if not hundreds of commercially available <glossary>HTML<\/glossary> editors have become available.\nThe HTML commands are similar, and also simpler, that those used by troff. In addition to formatting\ncommands, there are build in commands that tell the Web Browser to go out and retrieve a document.\nYou can also create links to specific locations (labels) within that document. Access to the\ndocument is by means of a <glossary>Uniform Resource Locator<\/glossary> (URL).\n<\/p>\n<question id=\"\" type=\"\" text=\"Which is the following is not typically used to access resources on the Web?\" \/>\n<p>\nThere are several types of URLs that perform different functions. Several different program can\nbe used to access these resources such as <glossary>ftp<\/glossary>,\n<glossary>http<\/glossary>, <glossary>gopher<\/glossary>, or even <command>telnet<\/command>.\nIf you leave off the program name, the Web browser assumes that it refers to a file on your local\nsystem. However, just like <command>ftp<\/command> or telnet you can\nspecifically make references to the local machine.\nI encourage using absolute names like that as it makes transferring Web pages that much easier.\n<\/p>\n<p>\nAll that you need to access the Web is an Internet connection. If you can do\n<command>ftp<\/command>\nand <command>telnet<\/command>, then you can probably use the Web. So, assuming you have a Web browser and an Internet\nconnection. The question is where do you go? The question is comparable to “Given a unlimited value\nplane ticket, where do you go on vacation?” The sky is the limit.\n<\/p>\n<p>\nAs I mentioned, the convention is that the Web server’s machine name is <i>www.domain.name<\/i>.\nTo access their home page, the <glossary>URL<\/glossary> would be <i>http:\/\/www.domain.name<\/i>. For\nexample, to get to your home page, the URL is <i>http:\/\/www.yourdomain.com<\/i>. In order to keep from typing so much, I will simply refer to the <glossary>domain<\/glossary>. name and you can expand it out the rest of the way. In some cases, where the convention is not followed, I’ll give you the missing information.\n<\/p>\n<p>\nI remember when comet Schumaker-Levy 9 was making history by plowing into the backside of\nJupiter. The Jet Propulsion Laboratory has a Web site, on which they regularly updated the\nimages of Jupiter. I still remember my friends asking me if I had seen the “lastest” images.\nIf they were more than three hours old, I would shrug them off as ancient history. With the explosion of the Internet and spread of webcams, it is now possible to get live images from all over the world, directly on your desk top.\n<\/p>\n<p>\nThe issue of Usenet <em>newsgroups<\/em> opens up a whole can of worms. Without oversimplifying\ntoo much, we could say that Usenet was the first, nation-wide on-line bulletin-board. Whereas the\nmore commercial services like CompuServe store their messages in a central location, Usenet is based\non the “store and forward” principle. That is, messages are stored on a message and forwarded to the\nnext at regular intervals. If those intervals are not all that often, it may be hours or even days before messages are propagated to every site.\n<\/p>\n<p>\nMessages are organized into a hierarchical, tree structure, very much like many things in\n<glossary>UNIX<\/glossary>. (although you don’t have to be running a UNIX machine to be accessing\nUsenet. Groups range from things like rec.arts.startrek.fandom to alt.sex.bondage to\ncomp.unix.admin.\n<\/p>\n<p>\nAlthough I would love to go into more details, this really goes beyond the scope of this book.\nInstead, I would like to recommend <i>Using <glossary>UUCP<\/glossary> and Usenet<\/i> by Grace Todino and Dale Dougherty, and <book isbn=\"\">Managing UUCP and Usenet<\/book> by Tim O’Reilly and Grace Todino, both from O’Reilly and Associates. In addition, there is a relatively new book that goes into more details\nabout how Usenet is organized, what newsgroups are available and some general information about\nbehavior and interaction with other when participating in a Usenet sendmail. This is <i>Usenet\nNetnews for Everyone<\/i> by Jenny Fristrup, from Prentice Hall.\n<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Accessing the Web It was difficult to decide where to put this topic. You can’t have access to the Web without networking, however, it looses much of it’s impact unless you are using a graphical interface like X. Because the … <a href=\"http:\/\/www.linux-tutorial.info\/?page_id=312\">Continue reading <span class=\"meta-nav\">→<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-312","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/312","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=312"}],"version-history":[{"count":1,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/312\/revisions"}],"predecessor-version":[{"id":492,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/312\/revisions\/492"}],"wp:attachment":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}