W3-The Internet and the Web.pdf

The Internet and the Web Click to edit Master subtitle style Computer Science and Health Informatics 2022-2023  Learning Objectives  The difference between Internet and Web​  History of the Internet​  How the Internet Works​? ...

The Internet and the Web Click to edit Master subtitle style Computer Science and Health Informatics 2022-2023  Learning Objectives  The difference between Internet and Web​  History of the Internet​  How the Internet Works​?  History of the Web​  How the Web Works​?  The difference between caching and cookies  The difference between intranet and extranet The Internet and the Web 2  Difference between Internet & Web  The Internet is a vast international network of computers. It is made up of hardware (computers & connections).  The World Wide Web is a collection of software that spans the Internet and enables the interlinking of documents and other resources (documents, images, sound clips). The Internet and the Web 3  History of the Internet History of the Internet ARPANet (precursor to Internet)  In 1969 it connected computers at four universities: UCLA, UCSB, SRI, and Utah so that researchers at different locations could communicate, share data, and run software remotely.  It used dedicated cables, buried underground (data transfer rate was 56K bits/sec)  By 1984, the ARPANet included more than 1,000 locations.  National Science Foundation (NSF) funded the construction of high-speed transmission lines that would form the backbone of the expanding network  In mid 90s the Internet was privatized. The network’s The term “Internet” was introduced to hardware are controlled by the telecommunications because of the similarities between this companies or Internet service provider (ISP) (e.g., AT&T, network and the interstate highway Verizon, Qwest, Sprint) system in US. The Internet and the Web 4  Internet  Internetworking (Internet) is a vast collection of smaller networks that have all agreed to communicate using the same protocols and to pass along messages so that they can reach their final destination.  It is the ultimate goal of WANs, spanning the entire globe.  Internet is serving many purposes and is involved in many aspects of life. Some of them are:  Data Communication and Computer Network  Web sites  E-mail  Instant Messaging  Blogging  Social Media  Marketing  Networking  Resource Sharing  Audio and Video Streaming 5  How the Internet Works? The design of the ARPANet was influenced by 2 key ideas: 1. Distributed network 2. Packet-switching Recall: As the ARPANet was funded by the US Department of Defense for communications and needed to be resistant to attack or mechanical failure The Internet and the Web 6  How the Internet Works How the Internet Works? In a packet-switching network:  messages are first broken into small pieces known as packets  these packets are sent independently to their final destination The Internet and the Web 7 Advantages of Packet Switchingntages of Packet Switching 1. Sending information in smaller units increases efficient use of redundant connections large messages can't monopolize the connection analogy: supermarket check-out and express lanes 2. Transmitting packets independently allows the network to react to failures or network congestion routers (special-purpose computers that direct the flow of messages) can recognize failures or congestion and reroute the packet around trouble areas 3. Breaking the message into packets can improve reliability since the packets are transmitted independently, it is likely that at least part of the message will arrive (even if some failures occur within the network), then software at the destination can recognize which packets are missing and request retransmission. The Internet and the Web 8  Protocols and Addressesrotocols and Addresses The Internet allows different types of computers from around the world to communicate  This is possible because the computing community agreed upon common protocols (sets of rules that describe how communication takes place)  The two central protocols that control Internet communication are: 1. Transmission Control Protocol (TCP) 2. Internet Protocol (IP) The Internet and the Web 9  IInternet Protocols: TCP/IP rnet Protocols: TCP/IP  Transmission Control Protocol (TCP)  controls the way messages are broken down into packets and then reassembled when they reach their final destination.  Internet Protocol (IP)  concerned with labeling the packets with the IP addresses of the source and destination devices and deals with the routing of packets through interconnected networks to the final destination The Internet and the Web 10  History of the Web of the Web The World Wide Web (WWW) is a multimedia environment in which documents can be linked over the Internet  Proposed by Tim Berners-Lee at the European Laboratory for Particle Physics (CERN) in 1989 Berners-Lee's design of the Web integrated two key ideas 1.Hypertext (document or text which contains links to other texts )  Web pages can contain images and links to other pages Hypertext example 2.The distributed nature of the Internet  Web pages can be stored on machines all across the Internet, known as Web servers  Logical connections between web pages are independent of their physical locations The web two key ideas The Internet and the Web 11  How the Web Works? The Web also relies on protocols to ensure that pages are accessible to any computer  HyperText Markup Language (HTML) it is a language used to develop webpages. It defines the structure, and the visual of web pages.  HTML5 is the current draft standard, supported by all modern browsers  HyperText Transfer Protocol (HTTP) is a communication protocol that is used to establish a connection with the web server to send back the web pages or other files to the user web browser to view it.  the prefix http:// in a URL specifies that the HTTP protocol is to be used in communicating with the web server The Internet and the Web 12  Viewing a web Viewing a web page page  A web page a text document that contains additional formatting information written in HTML  A website a collection of related web pages, usually designed and controlled by the same person or company  A web browser a software tool that retrieves, interprets and displays web pages ( e.g., Firefox, Safari, Microsoft edge, Chrome….)  A web server a computer that store webpages and it is set up to respond to requests for web pages The Internet and the Web 13  Web technologies Caching is the process done by the browser to store a copy of web pages or images along with a time stamp on a computer hard desk, to avoid redundant download and shorten webpages load time. The next time the web page/image is requested, it will first check the cache. If a copy is found, it sends a conditional request to the server essentially: "send this page/image only if it has been changed since the timestamp" if the server copy has not changed, the server sends back a brief message, and the browser simply uses the cached copy Workflow of opening a web page with caching Cookie is a small text file that a website stores on a computer’s hard disk that the website can retrieve later. It capture key information about a computer previous interactions with a website. Cookies are used to tell the server that users have returned to the website, determine the number of unique visitors to the website, personalized the interaction to the users and to maintain shopping cart from visit to visit. The Internet and the Web 14  Internet vs Intranets & Extranets Internet is a public network The world Intranet A private network, operated by an organization where only The Internet their employees can create content, access resources, communicate and collaborate. It is insulated from the global internet (does not allow access to anyone outside the organization network). Extranet Extranet Intranet A Private network that provides controlled access to authorized users from outside the organization to internal computers or resources (intranet) of the organization. The authorized users might be customers, vendors or Customers, Company only partners to allow them to communicate with the partners or organization in a closed and secure virtual space. suppliers The Internet and the Web 15  IntranetIntranet exampleexample https://www.ksau-hs.edu.sa/English/pages/e-services.aspx The Internet and the Web 16  Questions  A company would like to create a secure network, so only their employee can access some resources through it. Which type of network should you recommend for them? A. Internet B. Intranet C. Extranet D. ARPAnet  Which of the following is a function of HTTP ? A. Store a copy of a webpage in your hard desk to avoid redundant download of webpages B. Label the packets by the addresses of both sender and receiver C. Establish a connection with a web server to send back a webpage to browser to view it D. Determine the number of unique visitor to a website The Internet and the Web 17 The Internet and the Web 18