Introduction of Web programming Ins. Elaf Alhazmi LECTURE 1

What is Internet When two or more networks are connected, they become internetwork, or internet. Network : is group of connected communicating devices such as computers and printers. Internet is two or more networks that can communicate with each other Internet is a worldwide telecommunications system that provides connectivity for millions of other, smaller networks; therefore, the Internet is often referred to as a network of networks. It allows computer users to communicate with each other across distance and computer platforms 2 Ins.Elaf Alhazmi

What is Internet Today most end users who want Internet connection use the services of Internet service providers (ISPs). Internet services providers (ISPs). ISP is organization with one or more servers of local ISP by establishing service contract and paying fee. No company / or person owns the internet. it is a cooperative effort governed by system of standards and rules. The purpose of connecting computers together is to share information 3 Ins.Elaf Alhazmi

TCP/IP protocols The two most important protocols allowing computers to transmit data on the Internet are … Transmission Control Protocol (TCP) Internet Protocol (IP). With these protocols, virtually all computers can communicate with each other The Internet Protocol (IP) defines how data packets are sent across the Internet. It is like a mechanism for transmitting packets between source and destination 4 Ins.Elaf Alhazmi

What is World Wide Web The Internet is the collection of the many different systems and protocols. The World Wide Web (WWW), is repository ( مستودع ) of linked information spread all over the world. www, developed in Ins.Elaf Alhazmi

Difference between “Internet” & “WWW” The terms Internet and World Wide Web are often used interchangeably in everyday speech. The Internet is a particular global computer network connecting millions of computing devices The World Wide Web or Web is just one of many services running on the Internet. The Web is a collection of interconnected documents (web pages) and other Web resources, linked by hyperlinks and URLs 6 Ins.Elaf Alhazmi

Internet Application The main task of the internet is to provide services for users. Electronic mail (exchange of messages between two entities) File transfer (copying file one computer to another) Remote login (is a client-server application used to log into another computer on the Internet) Accessing World wide Web (WWW) 7 Ins.Elaf Alhazmi

Web Servers & Web Browsers Web page : a single document that is placed on internet Website : collection of web pages Web client/ browser: it requests for information The software that request for information is called the client. On the web, the browser is the client software that makes request for documents. 8 Ins.Elaf Alhazmi

Web Servers & Web Browsers Web server : it has websites stored, it accepts request from client and sends back information Web browser is piece of software on your computer or mobile device that you use to access web pages on websites For example Microsoft Internet Explorer Google Chrome Mozilla Firefox Safari opera 9 Ins.Elaf Alhazmi

Components of the WWW To use the WWW you need Three components… Browser (To display web pages) Servers ( Store Web sites) Hypertext Transfer Protocol (HTTP) 10 Ins.Elaf Alhazmi

Hypertext Transfer Protocol (HTTP) HTTP is protocol used mainly to access data on the World Wide Web. The idea of HTTP is very Simple. Client send a request to server, and then the server sends the response. 11 Ins.Elaf Alhazmi

Client-Server Architecture The Web has a client-server architecture with three fundamental components Web (client) browsers Network Web servers The request and response are handled via HTTP protocol, It can be used to transfer images, audio, videos etc all other web resources 12 Ins.Elaf Alhazmi

Addresses To identify one particular HTTP site, the client uses Uniform Resource Locator(URL) Uniform Resource Locator(URL) is standard for specifying any kind of information on the internet. The URL defines four things Method/protocol Host name Port Path 13 Ins.Elaf Alhazmi

Uniform Resource Locator(URL) For example… 1. Protocol : HTTP 2. Host: It has the website 3. Port : 80 for HTTP (optionally) 4. Path: location of file Protocol Host PORTPath 14 Ins.Elaf Alhazmi

Protocol The protocol part of an URL is the funny string of characters that you see before the hostname. Examples are http, ftp, telnet:, etc. They are separated from the hostname with a colon and two forward slashes ( :// ). These protocols tell your browser what type of service to use when you connect with the web browser to the hostname. If you leave the protocol off your address, by default the Web Browser will assume you are using the HTTP protocol, which is for connecting to web sites, so there is no need to type in the every time you go to a web site. If you specify another protocol like ftp, then the browser will act as an ftp client that will enable you to connect to a ftp server to download files. 15 Ins.Elaf Alhazmi

Hostname The hostname is the address you are going to. For example, if you are going to the address then is the hostname. 16 Ins.Elaf Alhazmi

Port Number The port number is a number that you can append to the hostname with a colon ( : ) between them. For example If you leave the port number off, which almost everyone does, then the browser will automatically use port 80 as that is the default port for the http protocol. Reserved Ports 80: Hypertext Transfer Protocol (HTTP) 20: File Transfer Protocol (FTP) 22: Secure Shell (SSH) 23: Telnet 25: Simple Mail Transfer Protocol (SMTP) 17 Ins.Elaf Alhazmi

Path This is the path on the server, culminating with the filename you are trying to reach. For example, the URL The path in this case is /examples/example1.html. This path corresponds to an actual directory structure on the web server. So on the web server there is a root directory, an examples directory underneath that root directory, and a file called example1.html underneath that. 18 Ins.Elaf Alhazmi

Domain name Server (DNS) An Internet address has four fields with numbers that are separated by periods or dots. This type of address is known as an IP address. For example Domain Name System (DNS) was developed to translate the numerical addresses into words for example 19 Ins.Elaf Alhazmi

Domain name Server (DNS) (DNS) is Unique name that identifies an entity, whether that be an single individual or a company, on the Internet It’s a part of host name in URL Domain Names always have 2 or more parts separated by the dots. The left most part is a specific name like yahoo This is a unique name and there cannot be any duplicates on the rest of the Internet that are used by anyone else. The right most part is top level domain (TLD) like.com,.edu,.gov ect 20 Ins.Elaf Alhazmi

Domain name Server (DNS) There are 2 different types of TLD Country code top level domain General top level domain Country code (cc)TLD specifies the country and only 2 letters are used like.sa,.ca,.au, Generic TLD(gTLD) used 3 or more letters like.com,.edu,.gov 21 Ins.Elaf Alhazmi

Country code top level domain.au Australia.deGermany.fr France.nlNetherlands.uk United Kingdom.us United States General top level domain.com Commercial.edu Educational.gov Government.net Networking Providers.org Organization.mil United States Military 22 Ins.Elaf Alhazmi

Cookies A cookie is information that a Web site puts on your hard disk so that it can remember something about you at a later time. A cookie is a mechanism that allows the server to store its own information about a user on the user's own computer The location of the cookies depends on the browser The main purpose of cookies is to identify users and possibly prepare customized Web pages for them. 23 Ins.Elaf Alhazmi

Cookies Type There are two types of cookies Session Cookies Persistent Cookies 24 Ins.Elaf Alhazmi

Session Cookies a cookie that is erased when the user closes the Web browser Session cookie has short time set for expiration like 20 min, 30 min, 2 hours, 8 hours Session cookies do not collect information from the user’s computer 25 Ins.Elaf Alhazmi

Persistent Cookies cookie that is stored on a user’s hard drive until it expires (persistent cookies are set with expiration dates) or until the user deletes the cookie Persistent cookies are used to collect identifying information about the user 26 Ins.Elaf Alhazmi

Documents on the WWW The documents on the WWW can be grouped into three categories Static documents Dynamic documents Active documents 27 Ins.Elaf Alhazmi

Static Documents Static documents are fixed-content documents that are created and stored on server. The client can only get copy of the document The contents are determined when the file is created, not when it is used. Programming languages Hypertext Markup language (HTML) Extensible Markup Language (XML) 28 Ins.Elaf Alhazmi

Dynamic Documents Dynamic document is created by web server whenever a browser requests the document. The server returns the output of the program as response to the browser that requested the document.( because fresh document is created for each request). Dynamic document Shows different information to different users. 29 Ins.Elaf Alhazmi

Dynamic Documents Programming languages Common Gateway Interface (CGI) New technology, it allows programmers to use several languages C,C++… etc Scripting technologies Hypertext preprocessor (PHP) Java Server Pages (JSP) Active server Pages (ASP) 30 Ins.Elaf Alhazmi

Active Documents Active documents are able to run program or script at the client site. The server send copy of document or script to client For example, to run a program that creates animated graphics on the screen. Programming languages Java applets Java script 31 Ins.Elaf Alhazmi