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Office and Internet Applications: Internet Applications 4. Internet Services and Resources The Internet provides various services and resources. In this section, we shall discuss how to find what you need, the major Internet applications and ways you can use the Internet to communicate with people, including e-mail, newsgroup, etc… 4.1 World Wide Web The World Wide Web (WWW) is a collection of electronic files among web servers on the Internet. By establishing a linked relationship between Web documents, related information becomes easily accessible. 4.1.1 Hypertext Transfer Protocol (HTTP) The primary function of HTTP is to establish a connection with a Web server and transmit HTML pages or any other files to the Web browser. Web Browser Web Server (HTTP server) 1. HTTP Request 2. HTML page TCP connection IP packets Web browsers communicate with Web servers via the TCP/IP protocol. The browser sends HTTP requests to the server, which responds by sending back messages and HTML pages. -1- 4.1.2 Hypertext Markup Language (HTML) Web documents are created using HTML which is a markup language, or tags, which is used to create Web pages. HTML tells the Web browser how to display the text contained in the Web pages. There are a number of user-friendly web authoring software, such as Dreamweaver, that allow you to generate HTML documents. The tags are inserted automatically for you in the web authoring software. Over the last decade, billions of Web pages have been created with HTML. Now, however, the World Wide Web Consortium has posted a more feature-rich standard – XHTML. HTML and XHTML are both widely accepted and used by Web developers. 4.1.3 Hyperlink In order to link Web pages to each other on the Internet, hyperlinks are used. Hyperlinks are instructions that point to other HTML documents, to another section of the same document (i.e. Bookmark) or to other multimedia elements on the Web. 4.1.4 Searching for Information on the Internet Basic strategic on searching Basically, there are two ways to search information on Internet by web browser. They are search engines and web directories. There are different web search strategies that help users to find information. A search engine is a software program that finds web sites and web pages. There are thousands of search engines exist. Some search on any topic and others are restricted to certain subjects, such as finding people or job hunting. -2- Popular search engines Search Engine Web address AltaVista http://www.altavista.com Excite http://www.excite.com Google http://www.google.com MSN Internet Search http://microsoft.msn.com Yahoo http://www.yahoo.com Effective Search Techniques To find information on the Internet efficiently, you had better read the search rules first because each search engine has different rules for formulating the inquiry. Besides, you can get results with more than one search engine. The results vary significantly between search engines, because their databases are compiled in completely different manners. Different results of the search contained from Yahoo and Google -3- 1. By keywords or phases It is the most widely used search method. The keywords and phrases you enter are critical to the success of your search. Choose them carefully and try to be as specific as you can. o Search Operator: You can use search operators in search expression. They are AND, OR and NOT. Search Operators AND OR NOT o Example China AND Canada China OR Canada China NOT Canada Explanation Find results with both China AND Canada Find results with China OR Canada Find results with China except Canada Wildcard Character: You can also use wildcard characters. Most search engines support these wildcard characters in their search expressions. A wildcard character allows you to omit part of a search term. Many search engines recognize the asterisk (*) as the wildcard character. For example, the search expression “wom*n” would return pages containing both woman and women. o Advanced Search: Many search engines have “Advanced Search” feature, which offers numerous options for making your searches more precise and getting more useful results. Users can search the results of web pages which are written in a certain language, created in a certain file format, that have been updated within a certain period of time, etc… See the following figure. -4- 2. Web directory Web directories use a completely different approach from search engines to build useful indexed of information on the Web. It is a listing of hyperlinks to Web pages that is organized into different categories. Users can click an appropriate category to find the information you want. There is plenty of useful and good quality information on the Internet. However, users may enter some harmful web sites and see some incorrect or indecent information by mistake carelessly. For example, methods of committing suicide had sometimes been introduced on web sites and sexual web-sites are plenty in the Internet. Besides choose carefully, we may avoid enter those web sites erroneously by screening them out using filtering software. In order to read only correct and good information on the Internet, we need to choose carefully and seek help from teachers when necessary. 4.1.5 File Transfer Protocol (FTP) The File Transfer Protocol (FTP) allows users to download and upload files on the Internet. An FTP server is a computer that allows users to upload and download files using FTP. An FTP site contains electronic files including text, graphics, audio clips, video clips and program files that reside on an FTP server. -5- You must have an authorized account (username and password) in order to access the FTP sites. Many FTP sites have anonymous FTP, i.e. anyone on the Internet can transfer files without prior permission. Using a Browser to Access FTP Site In the Microsoft Internet Explorer, type the Web address of FTP site FTP Client Program Users can download file using an FTP client program, such as WS_FTP LE program. FTP site address Anonymous login selected Type your e-mail address Click the “New” button in the Session Properties dialog box. Some ftp site allow anonymous logon. -6- Download button Winzip files Upload button Message Area Toolbar 4.2 Electronic Email (E-mail) E-mail is a common communications method in our society. Users can send and receive e-mail with anyone who has an e-mail address. We can use e-mail software or web-based e-mail to send or receive e-mail. The former one, such as Microsoft Outlook, enables e-mail though a program running on your computer. Web-based email is handled through interaction with a web site, such as Yahoo! Yahoo! Mail is one of the popular web-based e-mail Rabbit1.jpg Users can attach a file. Rabbit.jpg will be appended into the email. -7- The advantages of using e-mail client program are that e-mail can be integrated with other applications such as a calendar and task list. Besides, it can sign or encrypt e-mail message by sender, so that it provides better security level over using the Web-based e-mail approach. For the Web-based e-mail, it is easily accessible from any Internet-connected computer in the world. 4.2.1. Email Address An e-mail address is a combination of a user name and a domain name that identifies a user so he or she can receive Internet e-mail. An @ (pronounced at) symbol separates the user name from the domain name. [email protected] Username Domain Name The followings are several commonly used protocols for sending or receiving email. Simple Mail Transfer Protocol (SMTP) SMTP decides which paths an e-mail message takes on the Internet. It handles outgoing message. Post Office Protocol (POP) POP handles incoming messages. POP3 is the latest version of POP, which provides a message store that holds incoming e-mail until users log on and download it. Other protocols Internet Message Access Protocol (IMAP): IMAP is another protocol for retrieving mail message from a server. Multipurpose Internet Mail Extensions (MIME): MIME specifics how to encode non-text data, such as graphics and sound, so it can travel over the Internet. -8- 4.3 Newsgroup A newsgroup just likes a bulletin board. There are tens of thousands of newsgroups entertain global discussions on thousands of topics, including your favourite celebrities or professional teams. Newsgroups are organized by topic. The topic, and sometimes subtopics, is embedded in the newsgroup name. To participate in a newsgroup, user needs newsreader software or similar software that is built into most Internet browser clients. Nowadays, many newsgroups are maintained within the World Wide Web and newsreader software is not required. Name of newsgroup Name of topic Name of Sub-topic Newsgroup.computer.hardware Generally, newsgroups are public, anyone can post message and any posted replies to that message as a thread. It is a series of messages that are replies to each other. -9- Original Message Threads -10- 4.4 Online Chat 4.4.1 Chat Rooms An online chat is a real-time typed conversation that takes place on a computer. A chat room is a location on an Internet server that permits users to chat with each other. Anyone in the chat room can participate in the conversation, which usually is specific to a particular topic. Users only need to type a line of text on their computer keyboard, the words they enter display on the computer screens of other people in the same chat room. Some chat rooms support voice chats and video chats, in which people hear or see each other as they chat. 4.4.2 Instant Messaging (IM) Instant messaging is a real-time Internet communications service that notifies you when one or more people are online and then allows you to exchange messages or files or join a private chat room with them. Send an instant message Add people to the messenger list. -11- Join a chat room ICQ ICQ (pronounced “I seek you”) is one of the most popular instant messaging software programs available. Users can use ICQ for text chats, to send e-mail message, and to exchange files and URLs with other users. In addition, ICQ lets users chat with groups of people to participate in group meetings or to play games. 4.5 Webcasting Many companies use push Technology to webcast, or broadcast news. Web broadcasting is streaming audio or video over the Internet. Live or pre-recorded events can be transmitted to an unlimited worldwide audience. Streaming is a technology that refers to the continuous transmission of data, typically audio or video. Viewers only need the browser plug-ins from Real Player, Windows Media Player or QuickTime player to watch video. They also need a pair of speaker to hear the audio. RTHK Web site has broadcasting Radio and TV Plug-in Most Web browsers have the capability of displaying basic multimedia elements on a Web page. Sometimes, a browser might need an additional program, called a plug-in. Plug-in enables Web browsers to display or play a specific files, such as audio or video, that you request. When you install a Web browser, many popular plug-ins are often installed with it. When you encounter a -12- Web page that requires a plug-in you do not have, the Web page might display a message telling you that you are missing a required plug-in, or a dialog box might open and provide a way for you to install the missing plug-in. Missing plug-in name Common plug-in applications Type Document Multimedia Plug-in Application Description Acrobat Reader View, navigate and print Portable Document Format (PDF) files. Flash Player View dazzling graphics and animation, hear outstanding sound and music, display Web pages across an entire screen. QuickTime View animation, music, audio, video, etc… directly in a Web page. RealOne Player Shockwave Player Windows Media Player -13- Listen to live; stream audio and video content for faster viewing; play MP3 files; create music CDs. Experience dynamic interactive multimedia, 3-D graphics and streaming audio. Listen to live and audio; play or edit WMA and MP3 files; burn CDs; watch DVD movies.