Internet Applications Lecture 1 PDF

10/24/2024 INTERNET APPLICATIONS LECTURE 1 Dr. Mona Abbas  3 Agenda Web servers 24-Oct-24 4 What is the internet? The Internet is a global network of billions of computers and other...

10/24/2024 INTERNET APPLICATIONS LECTURE 1 Dr. Mona Abbas  3 Agenda Web servers 24-Oct-24 4 What is the internet? The Internet is a global network of billions of computers and other electronic devices that use a protocol to exchange data which is known as Hypertext Transfer Protocol, or HTTP. A markup language called Hypertext Markup Language, or HTML was created To bring these together, the first web browser and web server were created. 24-Oct-24 5 Web Browser Fetches/Displays documents from web servers Mozilla Firefox Microsoft Internet Explorer (IE) Apple Safari Google Chrome Opera Web Programming 24-Oct-24 6 Hypertext Transport Protocol (HTTP) Set of commands understood by a web server and sent from a browser Some HTTP commands (your browser sends these internally): GET filename : download POST filename : send a web form response // create new resource PUT filename : upload // update an exist resource Web Programming 24-Oct-24 7 Uniform Resource Locator (URL) Identifier for the location of a document on a web site Example: http://dept.ju.edu/cs/index.html Upon entering this URL into the browser, it would: Ask the DNS server for the IP address of dept.ju.edu Connect to that IP address at port 80 Ask the server to GET /cs/index.html Display the resulting page on the screen Web Programming  Servers Server refers to a computer or device on a network that manages network resources. There are different types of servers: 1. File server: a computer and storage device dedicated to storing files. Any user on the network can store files on the server. 2. Print server: a computer that manages one or more printers. 3. Network server: a computer that manages network traffic. It helps in providing various resources like hardware access, disk space, printer access. 4. Database server: a computer system that processes database queries. 8  WEB SERVER Web server can refer to either the hardware (the computer) or the software (the computer application) that helps to deliver web content that can be accessed through the Internet. Web Server Web Server is an IT (Information Technology) component that processes user requests via HTTP (Hypertext Transfer Protocol). A Web Server: Stores, process and deliver webpage to client. Web Server works as: → receive requests from client → generate response, and → send response to client. Web Server (cont.) A user agent initiates the communication by sending a HTTP request for the specific resource. Server processes the user request, search the requested content in its database (in documents and files). Responds with the content of that resource or an error message if unable to do so. Client side Vs. Server side Client side environment A client is a program, or machine, that connects and sends requests through the web browser to servers to perform actions. Client-side web development involves interactivity and displaying data. Server side environment A server is a program, or machine, that waits for incoming requests. It is a connection point for several clients, that will handle their requests. Server-side is the systems that run on the server. It is about working behind the scenes to manage data.  Types of Web Servers 15 16  Apache HTTP Server A public- domain open source Web server developed by the Apache Software Foundation. This is the most popular web server in the world. Apache web server can be installed on almost all operating systems including Linux, Unix, Windows,, Mac OS X and more. 17  18 Apache However, because the source code is freely available, anyone can adapt the server for specific needs, and there is a large public library of Apache add-ons. Popular sites using the Apache Web Server. Youtube.com Wikipedia.org Ask.com Apple.com 19  20 IIS Internet Information Services (IIS) for Windows Server is a flexible, secure and manageable Web server for hosting anything on the Web. Developer: Microsoft Corporation From media streaming to web applications, IIS's scalable and open architecture is ready to handle the most demanding tasks. Because IIS is tightly integrated with the operating system so it is relatively easy to administer it. It only runs and is bundled on Windows operating systems, but is otherwise free for use. 21  22 Nginx Nginx, stylized as NGINX, nginx or NginX. It is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache. The software was created by Igor Sysoev and publicly released in 2004. Nginx is free and open-source software. NGINX accelerates content and application delivery, improves security, facilitates availability and scalability for the busiest web sites on the Internet.  23 Nginx Today NGINX serves more than 146 million sites on the Internet. Successful online services use NGINX as part of their infrastructure such as: Netflix, Dropbox, Pinterest, WordPress.com, Instagram, GitHub and, SoundCloud. 24-Oct-24 24 Static Web Pages Web Programming 24-Oct-24 25 Static Web Pages Any content that can be delivered to an end user without having to be generated, modified, or processed. The server delivers the same file to each user, making static content one of the simplest and most efficient content types to transmit over the Internet. Web Programming 24-Oct-24 26 Static Web Pages Web Programming 24-Oct-24 27 Dynamic content Web content that changes based on the behavior, preferences, and interests of the user. Request for the same document returns different results depend on who made the request. The Web server needs to run certain programs(PHP, ASP, etc…) to process user requests. Web Programming 24-Oct-24 28 Dynamic content Web Programming 24-Oct-24 29 Dynamic content Web Programming 24-Oct-24 30 Web Development Web Programming  31 Web development Every dynamic website has two main parts: Part you see in Part that powers the front-end. browser and interact It’s behind the scene and with all the visual about storing data in dbs and aspects providing it to front-end.  32 Front-end web development 24-Oct-24 33 Web Languages Hypertext Markup Language (HTML): used for writing web pages Cascading Style Sheets (CSS): stylistic info for web pages PHP Hypertext Processor (PHP): dynamically create pages on a web server JavaScript: interactive and programmable web pages Web Programming  34 How the web works What happens the moment you type the address of a website in your browser and press Enter 35  36 Render DOM : builds the blocks or elements in our html document (paragraphs, images , links ….) Render: displaying those elements and blocks on the html document 37