Web Publishing (Ch. 11.4)

Transcription

1 Web Publishing (Ch. 11.4) Web publishing is the process of uploading web pages to a web server. Web server For a web page to be placed onto the Internet, it needs to be stored on a computer with the following capabilities: i. It must have a fixed IP address and always be connected to the Internet. ii. It must always be on, 24 hours a day. iii. It must have web server software, such as installed. Apache or Microsoft s Internet Information Services, These machines are called web servers. Domain Name To get to a web page, we type in the URL into the browser s address bar. The URL will start with something like: This is called the domain name. A domain name is the address of a web server, which is usually a unique to a certain IP address. text name corresponding For example, corresponds to the IP address The domain name provides a human-friendly way to memorize IP addresses. Structure of a Domain Name i. Top-level domain (TLD) a. Every domain name ends in a top-level domain (TLD) name. Also called first-level domains. b. Examples:.net,.com,.gov,.edu,.mil, etc. c. Also:.cn,.hk,.uk,.us,.ca,.sg, etc. ii. Second-level domain (SLD) a. The second-level domain (SLD) name is the string directly to the left of the TLD name. b. E.g. in google is the SLD. iii. Third-level domain a. The third-level domain name is directly to the left of the SLD. iv. There are at most 127 levels in a domain name. E.g. has 5 levels. Most domain names have 3 or 4 levels. v. Host name a. The left-most word, such as www, is the host name. b. It specifies the name of a specific machine providing specific service with a specific IP address on the Internet. WEB PUBLISHING TOOLS Page 1

2 is a machine running the web server software. mail.ktgss.edu.hk is a machine that is a mail server. CH/NSS ICT/Dec 2010 Keeping Track of Domain Names i. A non-profit organization called ICANN (Internet Corporation for Assigned Names and Numbers) maintains a database of registered domain names, and the contact information of the person or company who that name belongs to. ii. Companies called domain name registrars cooperate in maintaining the list of registered domain names, and make sure there are no duplicates. Domain Address to IP Address i. A distributed database keeps track of the domain name to IP address mapping. ii. Machines called domain name system (DNS) server remember the address mapping for the machines that they are responsible for. iii. Many big institutions have their own DNS servers that store the domain names and IP addresses of machines within their institution. iv. Many countries also maintain a DNS server for domain names within their jurisdiction. v. Every domain has a DNS server somewhere that handles requests for information from it. vi. Domain name system servers do two things: a. Accept requests from programs (like browsers ) to convert domain names to IP addresses. b. Accept requests from other DNS servers to convert domain names to IP addresses. vii. When a request comes into the DNS server, it can do the following: a. Return the corresponding IP address. b. Contact another DNS server to find the IP address for the given domain name. c. Return the IP address for another DNS server that might have the IP address for the given domain name. d. Return a domain not found error message if the domain name does not exist. viii. Example: Suppose we want to go to a. The browser contacts your ISP s DNS server and asks it for the IP address. b. The DNS server does not know this information, and thus contacts one of the root name servers, which know the IP addresses of all the name servers that handle the top-level domains. E.g. The root server returns the IP address of the.com DNS server. c. The ISP s DNS server contacts the.com DNS server and asks it for the IP address of google.com. d. The ISP s DNS server finally contacts the google.com DNS server and asks it for the IP address of ix. At each level, there are multiple name servers storing the same information to provide redundancy. WEB PUBLISHING TOOLS Page 2

3 Registering for a Domain Name CH/NSS ICT/Dec 2010 i. A web page hosted by a professional web hosting service will have an URL that includes the web hosting service s address in it. ii. It is also possible to make your web page s URL into something like or etc. iii. To do this, you need to register for your own domain name. Registering for a domain name is like trademarking a name. iv. It s a first-come, first-served process. v. Therefore, the first step is to make sure that nobody has registered the name that you want. a. Verisign.com maintains a service that searches the ICANN database for registered names. vi. The second step is to find a domain name registrar to register the name for you. a. Some examples: Netfirms.com, or Yahoo, or Register.com. b. ICANN also maintains a list of accredited registrars. c. The registrar will need your contact information and you will need to pay a fee. The fee will pay for you to keep your domain name for a set period of time, usually a year. After that period of time runs out, you will need to renew payment to keep your domain name. If you let your domain name expire, anybody else can come along and claim it. vii. Locally in Hong Kong, people can register domain names through their ISP or directly to Hong Kong Domain Name Registration Company Limited (hkirc.com) viii. Before registration, people can use the WHOIS service ( to see if the wanted domain name has been used. WEB PUBLISHING TOOLS Page 3

4 Web Hosting Web hosting refers to the provision of storage space and file maintenance service for web sites. Web pages of a web site are stored and maintained in a web server. Virtual Hosting i. Hosting a number of web sites in one web server. ii. Each web site has its own domain name. iii. The server has only one IP address. Non-virtual Hosting i. Hosting a number of web sites in one web server. ii. Each web site has a file directory name under the service provider s host domain name, e.g. iii. The server has only one IP address. Dedicated Hosting i. Hosting one web site in one web server. ii. The site owner has full of the dedicated server including choice of hardware and OS. Collocated Hosting i. Locating the site owner s dedicated web server with other ones servers on the premises of a web hosting service provider. ii. Those data centers are equipped with high Internet connection speed, physical security, air-conditioning and power supply. In-house Hosting i. The firms or organizations host their own web servers. ii. Factors like information traffic volume can be controlled better. iii. The firms or organizations have to deal security problems, like hackers and virus attacks, on their own. Thus they have to employ more technical workers. Parking Your Domain Name Once a domain name has been registered, you need to park it, or map it to your website on your web server. Get the information from the web host and give it to the domain name registrar. Wait hours for the domain name information to be updated to the DNS database. WEB PUBLISHING TOOLS Page 4

5 Uploading Your Web Page Uploading your web page to the web hosting service s machines usually involves a login, a password, and a directory. Many web authoring tools have a publish function built-in. Input the information from the web hosting service and press a button. Many web hosting services such as geocities also have web forms to take care of the publishing process. Otherwise, you may need to use an ftp client to upload your pages to the web server. Besides online tools offered by web sites, there are some common methods File transfer protocol (FTP) i. A user can upload files through the ftp client to the web server ii. MS DOS provides the basic FTP client program ftp iii. Basic requirements a. ftp/web server name b. Login ID and password c. Directories which allow to upload files iv. Other window-based ftp clients are widely available Secure CoPy (SCP) i. FTP is not safe enough. SCP offers a more secure file transfer ii. A user can upload files through the scp client to the web server iii. Some Window-based tools can be found at iv. Basic requirements a. Server name b. Login ID and password c. Directories which allow to upload files WEB PUBLISHING TOOLS Page 5