Module 1 - Web Programming Using PHP (CA4CRT13) PDF

MODULE -1 CA4CRT13 -Web Programming Using PHP Syllabus Introduction to the web, WWW architecture, Fundamentals of HTML, Text formatting tags, marquee, Inserting images, links, lists, Creating tables, Frames, Working with form elements. Internet Definition: The Internet is...

MODULE -1 CA4CRT13 -Web Programming Using PHP Syllabus Introduction to the web, WWW architecture, Fundamentals of HTML, Text formatting tags, marquee, Inserting images, links, lists, Creating tables, Frames, Working with form elements. Internet Definition: The Internet is a global network of interconnected computers that communicate with each other using standardized protocols. It is the underlying infrastructure that enables data exchange. Functionality: It allows various services, including email, file transfer, and web browsing, among others. Web/WWW/W3 The web is a system of interlinked hypertext documents and multimedia content that is accessed via the Internet using web browsers. Components: It consists of websites, web pages, and web applications, which are built using languages like HTML, CSS, and JavaScript. Functionality: It allows users to access and share information through hyperlinks, making it easy to navigate between different pages and resources.  WWW was created by Tim Berners Lee in 1989 at CERN in Geneva. WWW works on a client-server approach. The protocol used is HTTP (Hyper Text Transfer Protocol). Relationship B/w Internet and Web Dependency: The web relies on the Internet for its functionality. We need an Internet connection to access web content. Scope: The Internet encompasses a broader range of services beyond just the web, including email, VoIP, and file sharing, while the web specifically refers to the content and services accessed through web browsers. In summary, the Internet is the infrastructure that enables connectivity, while the World Wide Web is a service that operates on that infrastructure, facilitating access to information and resources. Client and Server A client can be a device or a machine. A client program runs on the local machine(like desktop, or smartphone), requesting service from the server. A client program is a finite program where the user starts the service and terminates when the service is completed. For instance, web browser.  A server is like a computer program, which is used to provide functionality to other programs. The server receives the request from the client for a web document, and it sends the requested information to the client's computer. Server has high efficiency and performance. Simultaneous multiple-user login and request processing are supported in servers. Some of the complex tasks like fulfilling client requests, storing and processing large datasets, data analysis are common for servers. Client and Server WEB SERVER A web server is a program that processes the network requests of the users and serves them with files that create web pages. This exchange takes place using Hypertext Transfer Protocol (HTTP). For example, you want to open Facebook on your laptop and enter the URL in the search bar of google. Now, the laptop will send an HTTP request to view the facebook webpage to another computer known as the webserver.  This computer (webserver) contains all the files which make up the website. After processing the request, the web server will send the requested website-related files to your computer and then you can reach the website. Examples of Web servers are- Facebook server,Appache HTTP sever etc. Website A website is a combination or collection of webpages grouped together, often handled by a person or an organization, which can be accessed anywhere and anytime by anyone via the internet. All these pages are linked together using the hyperlinks. Websites can also be either static or interactive. Some examples- e-commerce websites, social networking websites etc. Webpage Webpage, is a single document or page that is displayed in web browsers like the Firefox, Google Chrome, Opera. A unique URL address is also attached to the webpages and is used to render or access that particular page. Webpages can also be either static or dynamic. Examples- Home page , contact page, about page etc Domain Name A domain name is the name of the site that you put in the URL bar. A domain name is just the address to a website.  When you type in a domain name in the browser, it sent a request to a network of servers called the Domain Name System. These servers look up the domain in their records and send the request that you’re looking for their site. Protocol Protocol, a set of rules or procedures for transmitting data between electronic devices, such as computers. For computers to exchange information, there must be a preexisting agreement as to how the information will be structured and how each side will send and receive it.  Applications running on various devices can communicate using a group of protocols known as application layer protocols. These protocols support numerous services, including email, web browsing, and file transfer, and they define the structure and content of the transmitted data. 1. Hypertext Transfer Protocol (HTTP) The World Wide Web's foundational protocol is HTTP. It supports web client and server communication and loads web pages using hypertext links. An individual, known as the user-agent, requests a server using the client-server protocol known as HTTP. The user agent is typically a web browser. 2. File Transfer Protocol (FTP) FTP is an application layer protocol that transfers files between local and remote systems. 3. Domain Name System (DNS) DNS is a hierarchy and distributed naming system for computers, services, and other Internet resources or IP networks. DNS is responsible for translating domain names into IP addresses for locating and identifying computer services and devices with the underlying network protocols. 4. Simple Mail Transfer Protocol (SMTP) It is a widely used Internet protocol for sending emails between servers. 5. Post Office Protocol (POP) and Internet Message Access Protocol (IMAP) Email can be retrieved from a server and delivered to a local client using this application layer protocol. 6. Telnet Telnet enables users to sign in to a distant computer as if they were physically nearby. Architecture of WWW 2-tier architecture- That is client-server architecture. Browser acts as a client. Using the web browser, the user can send the request to the server to access the web page. The server provides a copy of the requested web page with additional information.