Các kiến thức "kỹ thuật" về web ....

Các kiến thức "kỹ thuật" về web ....

Chào các bạn,

Web đã hầu như là một phần nhỏ trong cuộc sống của giới trẻ ở VN . Dù là vậy, khi Thuyền về VN, để ý thấy họ chỉ là xài web thôi mà ít khi biết đến các kiến thức kỹ thuật sau chúng . Ngay chính cả các sinh viên cũng như giáo viên giảng dạy về web bên VN .

Vì vậy, Thuyền xin được phép kể từ nay sẽ thường xuyên "thẩy" bài về web lên đây cho các bạn đọc và tự trang bị lấy cho mình những kiến thức "under the hood" (slang, ý nói là kiến thức về xe hơi như mà là kiến thức dước cái hood của xe, kiến thức về máy móc, một lối nói so sánh vậy mà) về web .

Tiện đây, Thuyền ít có thì giờ vô trong đây nên các mod khác sẽ xử lý thắc mắc của các bạn . Tuy nhiên, Thuyền xin nhắc, chúng ta trong box này, mỗi người đều có chuyên ngành riêng cả . Tuy nhiên, điều đó không cấm chúng ta post chuyên ngành riêng của mình lên đây và đừng sợ bị loãng mà phải tìm forum mới . Thật ra thì nơi đây chính là nơi lý tưởng để các bạn tìm các đồng chí cùng ngành của riêng mình qua các thread chuyên ngành của mình . Nếu "đồng chí" (trời ơi, nghe sao giống như thời chiến tranh trước 75 quá) mà đông quá thì lúc đó có mở forum mới cũng là đoan chắc có members á ! (đi lạc đề, sorry).

Xin quay lại, Thuyền xin được post các kiến thức chuyên ngành của web trong đây .

Web rất rộng lớn, nhưng để focus, Thuyền xin được phép chú trọng vào các topics sau cho các bạn nha:

1. Basics về Communications
2. Wireless
3. Network Security
4. IP VPNs
5. Managing Corporate Networks
6. Network Access and Infrastructure Solutions
7. Voice over Packet
8. Market Studies
9. Industry Perspectives

(sorry, Thuyền không biết tiếng Việt khi viết về technical. Đơn giả là vì Thuyền học từ nhỏ bên đây, nếu bắt viết về technical = tiếng Viết thì Thuyền viết chậm lắm . Chịu khó đọc tiếng Anh kế từ đây đi nha các bạn !)

Topics thì viết theo thứ tự từ 1 đến 9 cho các bạn có thể tự học theo thứ tự đó . Cái sau sẽ đòi hỏi cái trước .

Tuy là vậy, nhưng Thuyền sẽ post ... tùy hứng của Thuyền nha các bạn ! Có được không vậy ? Bắt tui đi lại cái basic về Communications thì chán cho Thuyền lắm đó nha ! hihih

Ok, vậy bắt đây nha ....

Trời ơi, sau cái "bắt đầu nha" là cái ..... le lưỡi ?!
Vỗ ..... chân cái coi nào, các bác !!!!!
Bắt đầu đi hen Mod

Khổ ghê, cái website ttvnol này không cho phép upload các bài viết ở dạng .pdf format ! Chỉ cho upload hình lên thôi ! Thiệt đúng với lời đồn là ttvnol chỉ lập ra cho vui chơi xàm xàm mà thôi .
Để Thuyền liên lạc với những người bảo quản kỹ thuật của ttvnol xem tại sao họ lại giới hạn hình mà không cho upload document dạng pdf lên nhỉ ! Nếu mà họ không có khả năng thì thật là đáng tiếc vì kho tàng của Thuyền viết dưới dạng powerpoint hoac pdf mà thôi .

Nếu ttvn không hỗ trợ upload file.pdf hay các extension thì anh Thuyen upload taì liệu lên host của anh, rồi anh cho cái link để mọi người đến tham khảo. Được không anh Thuyen ?!

Cái basic của cái basics trước đây .
1.1 Internet
The Internet is a computer network made up of thousands of networks worldwide. No one knows exactly how many computers are connected to the Internet. It is certain, however, that these number in the millions and are growing.
No one is in charge of the Internet. There are organizations which develop technical aspects of this network and set standards for creating applications on it, but no governing body is in control. The Internet backbone, through which Internet traffic flows, is owned by private companies.
All computers on the Internet communicate with one another using the Transmission Control Protocol/Internet Protocol suite, abbreviated to TCP/IP. Computers on the Internet use a client/server architecture. This means that the remote server machine provides files and services to the user''''s local client machine. Software can be installed on a client computer to take advantage of the latest access technology.
An Internet user has access to a wide variety of services: electronic mail, file transfer, vast information resources, interest group membership, interactive collaboration, multimedia displays, real-time broadcasting, breaking news, shopping opportunities, and much more.
The Internet consists primarily of a variety of access protocols. Many of these protocols feature programs that allow users to search for and retrieve material made available by the protocol.
1.2 Basic Components của Internet
1.2.1 www
The World Wide Web (abbreviated as the Web or WWW) is a system of Internet servers that supports hypertext to access several Internet protocols on a single interface. Almost every protocol type available on the Internet is accessible on the Web. This includes e-mail, FTP, Telnet, and Usenet News. In ad***ion to these, the World Wide Web has its own protocol: HyperText Transfer Protocol, or HTTP. These protocols will be explained later in this document.
The World Wide Web provides a single interface for accessing all these protocols. This creates a convenient and user-friendly environment. It is not necessary to be conversant in these protocols within separate, command-level environments, as was typical in the early days. The Web gathers together these protocols into a single system. Because of this feature, and because of the Web''''s ability to work with multimedia and advanced programming languages, the Web is the fastest-growing component of the Internet.
The operation of the Web relies primarily on hypertext as its means of information retrieval. HyperText is a document containing words that connect to other documents. These words are called links and are selectable by the user. A single hypertext document can contain links to many documents. In the context of the Web, words or graphics may serve as links to other documents, images, video, and sound. Links may or may not follow a logical path, as each connection is programmed by the creator of the source document. Overall, the Web contains a complex virtual web of connections among a vast number of documents, graphics, videos, and sounds.
Producing hypertext for the Web is accomplished by creating documents with a language called HyperText Markup Language, or HTML. With HTML, tags are placed within the text to accomplish document formatting, visual features such as font size, italics and bold, and the creation of hypertext links. Graphics and multimedia may also be incorporated into an HTML document.
HTML is an evolving language, with new tags being added as each upgrade of the language is developed and released. For example, visual formatting features are now often separated from the HTML document and placed into Cascading Style Sheets (CSS). This has several advantages, including the fact that an external style sheet can centrally control the formatting of multiple documents. The World Wide Web Consortium (W3C), led by Web founder Tim Berners-Lee, coordinates the efforts of standardizing HTML. The W3C now calls the language XHTML and considers it to be an application of the XML language standard.
The World Wide Web consists of files, called pages or home pages, containing links to documents and resources throughout the Internet.
The Web provides a vast array of experiences including multimedia presentations, real-time collaboration, interactive pages, radio and television broadcasts, and the automatic "push" of information to a client computer. Programming languages such as Java, javascript, Visual Basic, Cold Fusion and XML are extending the capabilities of the Web. A growing amount of information on the Web is served dynamically from content stored in databases. The Web is therefore not a fixed entity, but one that is in a constant state of development and flux.
1.2.3 Email
Electronic mail, or e-mail, allows computer users locally and worldwide to exchange messages. Each user of e-mail has a mailbox address to which messages are sent. Messages sent through e-mail can arrive within a matter of seconds.
A powerful aspect of e-mail is the option to send electronic files to a person''''s e-mail address. Non-ASCII files, known as binary files, may be attached to e-mail messages. These files are referred to as MIME attachments.MIME stands for Multimedia Internet Mail Extension, and was developed to help e-mail software handle a variety of file types. For example, a document created in Microsoft Word can be attached to an e-mail message and retrieved by the recipient with the appropriate e-mail program. Many e-mail programs, including Eudora, Netscape Messenger, and Microsoft Outlook, offer the ability to read files written in HTML, which is itself a MIME type.
1.2.4 Telnet
Telnet is a program that allows you to log into computers on the Internet and use online databases, library catalogs, chat services, and more. There are no graphics in Telnet sessions, just text. To Telnet to a computer, you must know its address. This can consist of words (locis.loc.gov) or numbers (140.147.254.3). Some services require you to connect to a specific port on the remote computer. In this case, type the port number after the Internet address. Example: telnet nri.reston.va.us 185.
Telnet is available on the World Wide Web. Probably the most common Web-based resources available through Telnet have been library catalogs, though most catalogs have since migrated to the Web. A link to a Telnet resource may look like any other link, but it will launch a Telnet session to make the connection. A Telnet program must be installed on your local computer and configured to your Web browser in order to work.
With the increasing popularity of the Web, Telnet has become less frequently used as a means of access to information on the Internet.
1.2.5 ftp
FTP stands for File Transfer Protocol. This is both a program and the method used to transfer files between computers. Anonymous FTP is an option that allows users to transfer files from thousands of host computers on the Internet to their personal computer account. FTP sites contain books, articles, software, games, images, sounds, multimedia, course work, data sets, and more.
If your computer is directly connected to the Internet via an Ethernet cable, you can use one of several PC software programs, such as WS_FTP for Windows, to conduct a file transfer.
FTP transfers can be performed on the World Wide Web without the need for special software. In this case, the Web browser will suffice. Whenever you download software from a Web site to your local machine, you are using FTP. You can also retrieve FTP files via search engines such as FtpFind, located at http://www.ftpfind.com/. This option is easiest because you do not need to know FTP program commands.
1.2.6 Email discussion groups
One of the benefits of the Internet is the opportunity it offers to people worldwide to communicate via e-mail. The Internet is home to a large community of individuals who carry out active discussions organized around topic-oriented forums distributed by e-mail. These are administered by software programs. Probably the most common program is the listserv.
A great variety of topics are covered by listservs, many of them academic in nature. When you subscribe to a listserv, messages from other subscribers are automatically sent to your electronic mailbox. You subscribe to a listserv by sending an e-mail message to a computer program called a listserver. Listservers are located on computer networks throughout the world. This program handles subscription information and distributes messages to and from subscribers. You must have a e-mail account to participate in a listserv discussion group. Visit Tile.net at http://tile.net/ to see an example of a site that offers a searchablecollection of e-mail discussion groups.
Majordomo and Listproc are two other programs that administer e-mail discussion groups. The commands for subscribing to and managing your list memberships are similar to those of listserv.
1.2.7 Usenet news
Usenet News is a global electronic bulletin board system in which millions of computer users exchange information on a vast range of topics. The major difference between Usenet News and e-mail discussion groups is the fact that Usenet messages are stored on central computers, and users must connect to these computers to read or download the messages posted to these groups. This is distinct from e-mail distribution, in which messages arrive in the electronic mailboxes of each list member.
Usenet itself is a set of machines that exchanges messages, or articles, from Usenet discussion forums, called newsgroups. Usenet administrators control their own sites, and decide which (if any) newsgroups to sponsor and which remote newsgroups to allow into the system.
There are thousands of Usenet newsgroups in existence. While many are academic in nature, numerous newsgroups are organized around recreational topics. Much serious computer-related work takes place in Usenet discussions. A small number of e-mail discussion groups also exist as Usenet newsgroups.
The Usenet newsfeed can be read by a variety of newsreader software programs. For example, the Netscape suite comes with a newsreader program called Messenger. Newsreaders are also available as standalone products.
Usenet is not as popular nowadays as it once was. Blogs and RSS feeds are newer modes of communication that have caught the interest of Internet users.
1.2.8 Faq, rfc, fyi
FAQ stands for Frequently Asked Questions. These are periodic postings to Usenet newsgroups that contain a wealth of information related to the topic of the newsgroup. Many FAQs are quite extensive. FAQs are available by subscribing to individual Usenet newsgroups. A Web-based collection of FAQ resources has been collected by The Internet FAQ Consortium and is available at http://www.faqs.org/.
RFC stands for Request for Comments. These are documents created by and distributed to the Internet community to help define the nuts and bolts of the Internet. They contain both technical specifications and general information.
FYI stands for For Your Information. These notes are a subset of RFCs and contain information of interest to new Internet users.
1.2.9 Chat & instant messages
Chat programs allow users on the Internet to communicate with each other by typing in real time. They are sometimes included as a feature of a Web site, where users can log into the "chat room" to exchange comments and information about the topics addressed on the site. Chat may take other, more wide-ranging forms. For example, America Online is well known for sponsoring a number of topical chat rooms.
Internet Relay Chat (IRC) is a service through which participants can communicate to each other on hundreds of channels. These channels are usually based on specific topics. While many topics are frivolous, substantive conversations are also taking place. To access IRC, you must use an IRC software program.
A variation of chat is the phenomenon of instant messaging. With instant messaging, a user on the Web can contact another user currently logged in and type a conversation. Most famous is America Online''''s Instant Messenger. ICQ, MSN and Yahoo also offer chat programs.
(trích từ thư viện của truong đại học Albany, website http://library.albany.edu)
Được thuyenxaxu sửa chữa / chuyển vào 21:31 ngày 28/06/2005

Sơ sơ về internet rồi . Bây giờ, thì xin các bạn hiểu rõ thêm về www (World Wide Web) nha !

The World Wide Web is a system of Internet servers that supports hypertext to access several Internet protocols on a single interface. The World Wide Web is often abbreviated as the Web or WWW.
The World Wide Web was developed in 1989 by Tim Berners-Lee of the European Particle Physics Lab (CERN) in Switzerland. The initial purpose of the Web was to use networked hypertext to facilitate communication among its members, who were located in several countries. Word was soon spread beyond CERN, and a rapid growth in the number of both developers and users ensued. In ad***ion to hypertext, the Web began to incorporate graphics, video, and sound. The use of the Web has reached global proportions and has become a defining aspect of human culture in an amazingly short period of time.
Almost every protocol type available on the Internet is accessible on the Web. Internet protocols are sets of rules that allow for intermachine communication on the Internet. The following is a sample of major protocols accessible on the Web:
E-mail (Simple Mail Transport Protocol or SMTP)
Distributes electronic messages and files to one or more electronic mailboxes
Telnet (Telnet Protocol)
Facilitates login to a computer host to execute commands
FTP (File Transfer Protocol)
Transfers text or binary files between an FTP server and client
Usenet (Network News Transfer Protocol or NNTP)
Distributes Usenet news articles derived from topical discussions on newsgroups
HTTP (HyperText Transfer Protocol)
Transmits hyptertext over networks. This is the protocol of the Web.
Many other protocols are available on the Web. To name just one example, the Voice over Internet Protocol (VoIP) allows users to place a telephone call over the Web.
The World Wide Web provides a single interface for accessing all these protocols. This creates a convenient and user-friendly environment. Once upon a time, it was necessary to be conversant in these protocols within separate, command-level environments. The Web gathers these protocols together into a single system. Because of this feature, and because of the Web''s ability to work with multimedia and advanced programming languages, the Web is by far the most popular component of the Internet.

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HYPERTEXT AND LINKS: THE MOTION OF THE WEB

The operation of the Web relies primarily on hypertext as its means of information retrieval. HyperText is a document containing words that connect to other documents. These words are called links and are selectable by the user. A single hypertext document can contain links to many documents. In the context of the Web, words or graphics may serve as links to other documents, images, video, and sound. Links may or may not follow a logical path, as each connection is created by the author of the source document. Overall, the Web contains a complex virtual web of connections among a vast number of documents, graphics, videos, and sounds.
Producing hypertext for the Web is accomplished by creating documents with a language called HyperText Markup Language, or HTML. With HTML, tags are placed within the text to accomplish document formatting, visual features such as font size, italics and bold, and the creation of hypertext links. Graphics may also be incorporated into an HTML document.
HTML is an evolving language, with new tags being added as each upgrade of the language is developed and released. For example, visual formatting features are now often separated from the HTML document and placed into Cascading Style Sheets (CSS). This has several advantages, including the fact that an external style sheet can centrally control the formatting of multiple documents. The World Wide Web Consortium (W3C), led by Web founder Tim Berners-Lee, coordinates the efforts of standardizing HTML. The W3C now calls the language XHTML and considers it to be an application of the XML language standard.
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PAGES ON THE WEB

The World Wide Web consists of files, called pages or Web pages, containing information and links to resources throughout the Internet.
Web pages can be created by user activity. For example, if you visit a Web search engine and enter keywords on the topic of your choice, a page will be created containing the results of your search. In fact, a growing amount of information found on the Web today is served from databases, creating temporary Web pages "on the fly" in response to user queries.
Access to Web pages may be accomplished by:
Entering an Internet address and retrieving a page directly
Browsing through pages and selecting links to move from one page to another
Searching through subject directories linked to organized collections of Web pages
Entering a search statement at a search engine to retrieve pages on the topic of your choice
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RETRIEVING DOCUMENTS ON THE WEB: THE URL and DOMAIN NAME SYSTEM

URL stands for Uniform Resource Locator. The URL specifies the Internet address of a file stored on a host computer connected to the Internet. Every file on the Internet, no matter what its access protocol, has a unique URL. Web browsers use the URL to retrieve the file from the host computer and the specific directory in which it resides. This file is downloaded to the user''s client computer and displayed on the monitor connected to the machine.
URLs are translated into numeric addresses using the Domain Name System (DNS). The DNS is a worldwide system of servers that stores location pointers to Web sites. The numeric address, called the IP (Internet Protocol) address, is actually the "real" URL. Since numeric strings are difficult for humans to use, alphneumeric addresses are employed by end users. Once the translation is made by the DNS, the browser can contact the Web server and ask for a specific file located on its site.
Anatomy of a URL
This is the format of the URL:
protocol://host/path/filename
For example, this is a URL on the Web site of the U.S. House of Representatives:
http://www.house.gov/house/2004_House_Calendar.html
This URL is typical of addresses hosted in domains in the United States.
Structure of this URL:
1. Protocol: http
2. Host computer name: www
3. Second-level domain name: house
4. Top-level domain name: gov
5. Directory name: house
6. File name: 2004_House_Calendar_html
Note how much information about the content of the file is present in this well-constructed URL.
Other examples:
telnet://locis.loc.gov the catalog of the Library of Congress
ftp://ftp.sunsite.auc.dk/projects/cgfa/picasso/p-picasso11.jpg a file on an ftp site
Several top-level domains (TLDs) are common in the United States:
com : commercial enterprise
edu : educational institution
gov : U.S. government entity
mil : U.S. military entity
net : network access provder
org : usually nonprofit organizations
New domain names were approved in November 2000 by the Internet Corporation for Assigned Names and Numbers (ICANN): .biz, .museum, .info, .pro (for professionals) .name (for individuals), .aero (for the aerospace industry), and .coop (for cooperatives). ICANN continues to investigate proposals for addding ad***ional domain names, for example, .mobi for sites designed for mobile devices, and .jobs for the human resources community.
In ad***ion, dozens of domain names have been assigned to identify and locate files stored on host computers in countries around the world. These are referred to as two-letter Internet country codes, and have been standardized by the International Standards Organization as ISO 3166. For example:
ch ---> Switzerland
de ---> Germany
jp ----> Japan
uk ----> United Kingdom
As the technology of the Web evolves, URLs have become more complex. This is especially the case when content is retrieved from databases and served onto Web pages. The resulting URLs can have a variety of elaborate structures, for example,
http://spills.incidentnews.gov/incidentnews/FMPro?-db=images&-Format=maps.htm&SpillLink=8&Subject=Waterway%20Closure%20Map&-SortField=EntryDate&-SortOrder=descend&-SortField=EntryTime&-SortOrder=descend&-Token=8&-Max=20&-Find
The first part of this URL looks familiar. What follows are search elements that query the database and determine the order of the results. As a growing number of databases serve content to the Web, these types of URLs will appear more commonly in your browser''s address window.
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HOW TO ACCESS THE WORLD WIDE WEB: WEB BROWSERS

To access the World Wide Web, you must use a Web browser. A browser is a software program that allows users to access and navigate the World Wide Web. There are two types of browsers:
Graphical: Text, images, audio, and video are retrievable through a graphical software program such as Internet Explorer, Firefox and Netscape. These browsers are available for Windows, Apple, Linux and other operating systems. Navigation is accomplished by pointing and clicking with a mouse on highlighted words and graphics.
You can install a graphical browser on your computer. For example, Internet Explorer is a part of the Windows operating system, and is also available on the Microsoft site: http://www.microsoft.com/. Firefox is available for downloading from http://www.mozilla.org/products/firefox/ and Netscape is available from http://home.netscape.com/.
Text: Lynx is a browser that provides access to the Web in text-only mode. Navigation is accomplished by highlighting emphasized words in the screen with the arrow up and down keys, and then pressing the forward arrow (or Enter) key to follow the link. In these days of graphical browsers, it may be hard to believe that Lynx was once very popular. For more information, see Guide to Using Lynx.
Extending the Browser: Plug-Ins
Software programs may be configured to a Web browser in order to enhance its capabilities. When the browser encounters a sound, image or video file, it hands off the data to other programs, called plug-ins, to run or display the file. Working in conjunction with plug-ins, browsers can offer a seamless multimedia experience. Many plug-ins are available for free.
File formats requiring plug-ins are known as MIME types. MIME stands for Multimedia Internet Mail Extension, and was originally developed to help e-mail software handle a variety of binary (non-ASCII) file attachments. The use of MIME has expanded to the Web. For example, the basic MIME type handled by Web browsers is text/html associated with the file extention .html.
A common plug-in utilized on the Web is the Adobe Acrobat Reader. The Acrobat Reader allows you to view documents created in Adobe''s Portable Document Format (PDF). These documents are the MIME type "application/pdf" and are associated with the file extension .pdf. When the Acrobat Reader has been downloaded to your computer, the program will open and display the file requested when you click on a hyperlinked file name with the suffix .pdf. The latest versions of the Acrobat Reader allow for the viewing of documents within the browser window.
Web browsers are often standardized with a small suite of plug-ins, especially for playing multimedia content. Ad***ional plug-ins may be obtained at the browser''s Web site, at special download sites on the Web, or from the Web sites of the companies that created the programs.
Once a plug-in is configured to your browser, it will automatically launch when you choose to access a file type that it uses.
Beyond Plug-Ins: Active X
ActiveX is a technology developed by Microsoft which make plug-ins less neccesary. ActiveX offers the opportunity to embed animated objects, data, and computer code on Web pages. A Web browser supporting ActiveX can render most items encountered on a Web page. As just one example, Active X allows you to view and e*** PowerPoint presentations directly within your Web browser. ActiveX works best with Microsoft''s Internet Explorer.
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Chúc các bạn một ngày học về web vui vẻ nha ....

1.1 Internet
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Sơ sơ về internet rồi . Bây giờ, thì xin các bạn hiểu rõ thêm về www (World Wide Web) nha !
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The World Wide Web is a system of Internet servers that supports hypertext to access several Internet protocols on a single interface. The World Wide Web is often abbreviated as the Web or WWW.
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THE EXPERIENCE OF THE WEB

Today''s World Wide Web presents an ever-diversified experience of multimedia, programming languages, and real-time communication. There is no question that it is a challenge to keep up with the rapid pace of developments. The following presents a brief description of some of the more important trends to watch.
Multimedia
The Web has become a broadcast medium. It is possible to listen to audio and video over the Web, both pre-recorded and live. For example, you can visit the sites of news organizations and view the same videos shown on the nightly news. Several plug-ins are available for viewing these videos.
At one time, the entire multimedia file had to be downloaded before viewing. Since these types of files tend to be quite large, download times can be lengthy. This problem has been answered by a revolutionary development in multimedia capability: streaming media. In this case, audio or video files are played as they are downloading, or streaming, into your computer. Only a small wait, called buffering, is necessary before the file begins to play.
The Windows Media Player, RealPlayer and QuickTime plug-ins play streaming audio and video files. Extensive files such as interviews, speeches and hearings work very well with these players. They are also ideal for the broadcast of real-time events. These may include live radio and television broadcasts, concerts, Web-only broadcasts, and so on. A list of selected sites that make use of these programs is available on the page, Multimedia on the Web.
Shockwave and Flash are plug-ins that provide another multimedia experience. They offer the creation and implementation of an entire multimedia display combining graphics, animation and sound.
Sound files, including music, are also a part of the Web experience. Sound files may be incorporated into Web sites, and are also available for downloading independent of Web site visits. For example, try the search engine FindSounds.com. Sound files of many types are supported by the Web with the appropriate plug-ins. The MP3 file format, and the choice of supporting plug-ins, is one of the most popular music trends to sweep the Web.
Live cams are another aspect of the multimedia experience available on the Web. Live cams are video cameras that send their data in real time to a Web server. These cams may appear in all kinds of locations, both serious and whimsical: an office, on top of a building, a scenic locale, a special event, and so on.
Programming Languages and Functions
The use of existing and new programming languages have extended the capabilities of the Web. What follows is a basic guide to a group of the more common languages and functions in use on the Web today.
CGI, Active Server Pages: CGI (Common Gateway Interface) refers to a specification by which programs can communicate with a Web server. A CGI program, or script, is any program designed to accept and return data that conforms to the CGI specification. The program can be written in any programming language, including C, Perl, and Visual Basic Script. A common use for a CGI script is to process a form on a Web page. For example, you might fill out a form to order a book at Amazon. The script processes your information and sends it to Amazon to process your order.
Another type of dynamically generated Web page is called Active Server Pages (ASP). Developed by Microsoft, ASP is a programming environment that processes scripts on the Web server. The scripts run on the server, rather than on the Web browser, to generate the HTML pages sent to browsers. Visual Basic and JScript (a subset of JavaScript) are often used for the scripting. ASPs end in the file extension .asp or .aspx.
Java/Java Applets: Java Java is an object-oriented programming language similar to C++. Developed by Sun Microsystems, the aim of Java is to create programs that will be platform independent. The Java motto is, "Write once, run anywhere." A perfect Java program should work equally well on a PC, Macintosh, Unix, and so on, without any ad***ional programming. This goal has yet to be realized. Java can be used to write applications for both Web and non-Web use.
Web-based Java applications are usually in the form of Java applets. These are small Java programs called from an HTML page that can be downloaded from a Web server and run on a Java-compatible Web browser. A few examples include live newsfeeds, moving images with sound, calculators, charts and spreadsheets, and interactive visual displays. Java applets can tend to load slowly, but programming improvements should lead to a shortened loading time.
JavaScript/JScript: JavaScript is a programming language created by Netscape Communications. Small programs written in this language are embedded within an HTML page, or called externally from the page, to enhance the page''s the functionality. Examples of JavaScript include moving tickers, drop-down menus, real-time calendars and clocks, and mouse-over interactions. JScript is a similar language developed by Microsoft and works with the company''s Internet Explorer browser.
VRML: VRML (Virtual Reality Modeling Language) allows for the creation of three-dimensional worlds. These may be linked from Web pages and displayed with a VRML viewer. One of the most interesting aspects of VRML is the option to "enter" the world and control your movements within the world.
XML: XML (eXtensible Markup Language) is a mark-up language that enables Web designers to create their own customized tags to provide functionality not available with HTML alone. XML is a language of data structure and exchange, and allows developers to separate form from content. With XML, the same content can be formatted for multiple applications. In May 1999, the W3 Consortium announced that HTML 4.0 has been recast as an XML application called XHTML. This move is slowing having an impact on the future of both XML and HTML.
Real-Time Communication
Text, audio and video communication can occur in real time on the Web. This capability allows people to conference and collaborate in real time. In general, the faster the Internet connection, the more successful the experience.
At its simplest, chat programs allow multiple users to type to each other in real time. Internet Relay Chat and America Online''s Instant Messenger are prime examples of this type of program. The development of a messenging protocols is underway. Such a protocol would allow for the expansion of this capability throughout the Internet.
More enhanced real-time communication offers an audio and/or video component. CU-See Me is a sotware programs of this type. Even more elaborate are programs that allow for true real-time collaboration. Microsoft''s NetMeeting and Netscape''s Conference (available with Communicator) are good examples of this.
Featured collaboration tools include:
audio: conduct a telephone conversation on the Web
video: view your audience
file transfer: send files back and forth among participants
chat: type in real time
whiteboard: draw, mark up, and save images on a shared window or board
document/application sharing: view and use a program on another''s desktop machine
collaborative Web browsing: visit Web pages together
Currently no standard exists that will work among all conferencing programs.
Push: Push refers to a technology that sends data to a program without the program''s request. This is the opposite of the typical "pull" of the Web, in which the user clicks on a link to request a file from a server. With push, the data is sent automatically. Content is sent through a "channel." The early Web-based implementation of push was commercial. Push can also be used to deliver software upgrades to desktop machines. At one time, push was considered to be The Next Big Thing for the Web. This has not materialized.
Current Trends: Blogs and RSS
The Web is a welcoming medium for experimentation and user participation. It is becoming easier to post Web content and share comments with other users. The idea of the Web site is still very much alive, but Web participation is taking new forms and being driven by new technologies. Here are two of the latest trends.
Blogs: A blog is an easy-to-create Web site that allows users to share their thoughts with the world managed by a lightweight content management system. The word "blog" comes from "Weblog" because a blog consists of a signed and dated log of individual postings. The topic of the blog can be anything, from the personal to the professional. A blog is what you make of it.
What is important about blogs is the content management system that manages the content. This system can offer a variety of features that can make the blog a useful tool. Examples include a calendar view of postings, organization of postings into categories, archived postings, options to send e-mail notification of new postings, and so on.
Blogging can be an interactive activity. Readers can add comments to a blogger''s postings, other can respond, and a conversation ensues. Lately, bloggers have become well-known commentators on the political scene, but blogging can encompass any topic or no topic at all. If the blogging software allows it, bloggers can use RSS to distribute their postings.
Visit Bloogz, a search engine devoted to locating blogs. You can set up your own blog by visiting Blogger.
RSS: RSS allows people to place news and other announcement-type items into a simple XML format that can then be pushed to RSS readers and Web pages. The initials RSS can stand for different things, including Rich Site Summary or Really Simple Syndication. Users can subscribe to the RSS newsfeeds of their choice, and then have access to the updated information as it comes in. RSS is used for all kinds of purposes, including the news itself and announcing new content on Web sites.
RSS content may be read by using an RSS reader, or aggregator. This is usually free software that you can install on your computer that posts new items and stores old ones in a graphical interface. An RSS reader similar to e-mail software in that it displays incoming items and can store content for offline reading. Subscribing to a newsfeed is usually as simple as entering the address of the RSS document.
A useful list of RSS readers is available on the site of Weblogs Compendium: http://www.lights.com/weblogs/rss.html
It is also possible *****bscribe to and read your own collection of RSS feeds on Web sites devoted to this purpose. Bloglines (at website : http://www.bloglines.com/) is one such example. The advantage here is that you can access your RSS feeds from any computer that is connected to the Web.
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(trích từ Albany university)

Cảm ơn anh Thuyền lắm lắm. Web thì ai cũng biết ít nhiều, từ email, chat, Internet, cho đến 1 số bạn chịu khó còn tạo website tĩnh, blog của riêng mình, website động,,.nhưng mà có cái nhìn tổng thể thế này thì cần người dày dạn chịu khó chinh chiến ha.
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KÍNH GỬI: BÁC THUYENXAXU!
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Anh Lan ơi, em tò mò chút, anh viết cái Project đó bằng ngôn ngữ hay script gì vậy ?
Ngày xưa thì em thấy có 1 nhóm web trong công ty hay viết bằng JSP, ASP, ở đây em thấy mấy đứa dùng Perl kết hợp với HTML. Em không biết chỗ anh thì dùng gì vậy á?