Interview with Mr Patrick Chan, BBS, JP Director of ... - å¬åå¡äºåå±

More documents

Recommendations

Info

Dissecting the Web:What actually happenswhen youon a hyperlink?14The founding of the World Wide Web, an extensivenetwork connecting the entire world, hasfundamentally changed the world. Information,conversations and business transactions are nowtraversing freely from anywhere in the world toanywhere else in the world instantly, unhinderedby geographical constraints.Leveraging this enormous advantage, web-basedIT systems have also been widely deployedin government and businesses to increaseproductivity through connectivity. These days,many government systems embrace a web-baseddesign – using the same technologies as the Web.In a web-based system, the user gains accessthrough a web browser, such as the InternetExplorer. Some examples are the Central CyberGovernment Office (CCGO), and theTreasury Intranet. To further dissectthe Web, this article will explore threefundamental concepts empowering theWeb - how information is transmitted,presented and processed.Transmitting Information –Web FunctioningThe best way to illustrate how theWeb works would be emulating theprocess of a user surfing the Web.On the Internet, many web servers are set upto host websites for Internet users, known asclients. The process begins when the clientdecides to access a certain website, such as theGovernment’s website. The first step they take is totype the Uniform Resource Locator (URL) -“www.gov.hk” - into the address box. In doing so,the user directs their own computer to send arequest to the appropriate web server. The requestis then formatted into network packets, whichare basic units of information for transmittingsignals over the network, in accordance withvarious protocols. The network packets will bestamped with the URL for navigation reference.Now that the data is converted into a transmissionreadyformat, how does the computer knowwhere “www.gov.hk” is? When the request issent out from a computer onto the Web, itarrives at a DNS server for further routing. DNSservers are interconnected servers specialisedin implementing the DNS – a lookup mechanismthat translates the textual URL (www.gov.hk) intoan Internet Protocol (IP) address, a uniqueidentification for a device connected to theInternet. Network packets sent from a computerwould be routed to a DNS server to determine itsdestination based on the IP address. When thestreams of packets reach the destination, they aredecoded by the same sets of protocols and theWeb server then interprets the request and sendsback the data at www.gov.hk. The data, in anotherstream of network packets, will then travel backto the client for display in the users’ web browser.The illustration below briefly outlines the topologyof the Web and the workflow of transmission:1 User wants to go to the website“www.gov.hk”. The computer generatesa request to access www.gov.hk.2 The request is converted intotransmission-ready Networkpackets in accordance withthe various protocols.Protocols:E.g. HyperTextTransferProtocol(HTTP)DNS Server4 The DNS server matches the phrase“www.gov.hk” with the stored IP addressaccording to the Domain Name System.The World Wide Web3 The network packets containing therequest is sent out from the user’scomputer to a DNS Server.5 The request isthen routed to202.128.243.212.DNS Checking:Name:www.gov.hkIP Address:202.128.243.212Content Display –Web Servers and HTMLWeb Server(www.gov.hk)6 The request is then converted backto understandable form by the webserver. The web server processes therequest and returns the webpage tothe user in a similar manner.With the fundamental concept of data transmissionover the Web explained, how does the Web enablethe presentation of information in such a way thatall computers can consistently comprehend andreplicate it? To begin with, you will probably recallthat the Web consists of an astronomically largenumber of websites. A website is run by a Webserver, which is a computer dedicated to storingall information of a website and rendering themaccessible by other users on the Internet. A Webserver has its own IP address to enable accessfrom other computers. It processes any incomingrequests from users and returns the appropriate
website content as requested. Web servers areessentially “serving” the many users on the Web,similar to the storefront of shops.How does a website run on a web server? Firstly,a website comprises many web pages. Webpages are typically stand-alone files, with the enddenoted as “.html” or “.htm”. They are written ina common language known as the Hyper-textMarkup Language (HTML). Web pages arestored as HTML files on the Web server, andare made available for fetching by the user whenrequested. The entire HTML file will be sent backto the user and be displayed on a Web browser.All Web browsers are built to understand andprocess HTML files, much like having a commonlanguage to speak in the real world. In short,HTML is a universal language for presentationof data in Web browsers.The primary purpose of HTML is to properlyformat and display static information on a Webbrowser. The HTML is derived from the conceptof “marking up” a document, with tags to annotatethe display styles of elements in a document.Textual information in a web page is stored in thecorresponding HTML file. If a web page needsto incorporate images, instead of containing theimage itself, the HTML file contains a referenceto where the image is placed. The same conceptapplies to other multimedia information, such asmovies. For example, most animations displayedon the Web nowadays are in the format of AdobeFlash videos. A Flash Video file is separatelystored and will be embedded into a web page filevia a reference.Different pages of a website are interconnectedwith hyperlinks. As an HTML feature, hyperlinksare special text on a web page that redirects auser to another page when clicked. They areusually highlighted in blue and underlined to bedistinguished from normal text.In summary, since all Web browsers are capableof interpreting and displaying HTML, websites builtwith HTML files can be presented consistently byall computers through a Web browser.Beyond Static Presentation –Dynamic Websites and ProcessingVery often websites have interactive componentsthat process incoming information and produceoutputs based on user inputs. A simple examplewould be a search engine. A user types in akeyword, such as “chocolate”, into a textbox andthe search engine will return relevant websitesand information on chocolate. The ability of thewebsite to process the keyword is beyond thescope of HTML, which is only responsible fordisplay and formatting. Websites capable ofproducing different results based on differentinputs are under the concept of dynamicwebpage generation. This concept is driven byanother important technology known as serversidescripting which allows Web servers toemploy customised programming to controldynamic outputs of a website. With server-sidescripting technology, a web server can generateweb pages containing processed informationbased on inputs received by users. Some popularserver-side scripting technologies are PHP, ASP.NET and JSP. It is important to note that whilethe file types have changed, the output format isstill expressed in HTML codes. The relationshipbetween server-side scripting technology andHTML pages can be expressed as a projector –the projector (server-side scripting) will projectdifferent images (HTML pages) as required bythe user, based on user input.ConclusionThe dissection of the Web begins withunderstanding the basic concept of transmissionof information over the Internet followed bythe concept of how information is universallypresented on websites with HTML. To further thestudy of the Web and its revolutionary impact, thisarticle has briefly introduced server-side scriptingtechnology. While HTML has facilitated simpleinformation sharing over the Web, it is server-sidescripting technology that truly revolutionises theuse of the Internet for a multitude of purposes.Through web-based IT systems, Internet userscan now trade stocks, pay taxes, keep in touchwith friends and families afar, and even runbusinesses. To date, these important buildingblocks of the Web are constantly being developedand enhanced, trailblazing even more inspiringand creative inventions to benefit the immersiveon-line experience.Raymond SzetoEOII(Antiquities & Monuments)Leisure and Cultural Services Department 15
Page 3: Patrick Chan, BBS, JP,of General Gr
Page 8 and 9: 多走半步整個訪問 ,
Page 10 and 11: 由左至右 : 陳振華、
Page 12 and 13: As part of the Human Resource Manag
Page 16 and 17: 行家小檔案 -在忙碌
Page 18 and 19: Book Review onThe 5 Languages ofApp
Page 20 and 21: News from theGeneral Grades OfficeA
Page 22 and 23: T rainingCongratulations to 20 coll
Page 24: 帶領讀者探索寫作的

Interview with Mr Patrick Chan, BBS, JP Director of ... - å ¬åå¡äºåå±

Create successful ePaper yourself

Delete template?

Save as template?

Interview with Mr Patrick Chan, BBS, JP Director of ... - å¬åå¡äºåå±