Introduction to Network Applications & Network Services

Introduction to Network Applications & Network Services

1. Data Communications Introduction to Network Applications & Network Services

2. How Networks Impact Daily Life The benefits of instantaneous communication via network have greatly improved our lives.

3. How Networks Impact Daily Life Communication over a network has also greatly changed the way we work.

4. How Networks Impact Daily Life and also changed the way we study….

5. How Networks Impact Daily Life the way we entertain ourselves….

6. Common Network Applications Introducing some common network applications & screenshots

7. Internet & Daily Life When you access the Internet, do you use the following applications? Google Chrome , Firefox, Google Mail, Hotmail, Yahoo Mail, Yahoo Messenger, MSN Messenger, Skype Facebook, Online games and others…. Since these applications require the access to the Internet, we refer these applications as network applications .

8. Google’s Google Chrome Perhaps, the most frequently used network application in your daily life is Google Chrome . You use Google Chrome to Check your Hotmail or Google Mail. Reading news (e.g. cnn.com) Access to Facebook Downloading movies, games, etc… In fact, Google Chrome is categorically called a Web Browser .

9. Web Browser By definition: A web browser is a network application for retrieving, presenting, and traversing information resources on the World Wide Web. The following network applications (web browsers) do the same thing as Internet Explorer : Internet Explorer Mozilla Firefox Netscape Opera Safari Camino Konqueror and others…. Netscape 2.0 is The browser that make the Internet or World Wide Web into a global phenomena back in 1996.

10. Other Web Browsers’ Screenshots S afari Google Chrome

11. Other Web Browsers’ Screenshots Firefox O pera

12. Instant Messaging Another popular network application beside the web browsers is Instant Messaging . Instant messaging (IM) is a form of real-time direct text- based communication between two or more people using personal computers (PCs) or other devices. More advanced instant messaging software also allow live voice or video calling. Some of the popular instant messaging software: WeChat Skype Windows Live Messenger Yahoo! Messenger Google Talk Facebook Telegram

13. Screenshots of Other Instant Massagers

14. E m ai l For all business activities via the Internet, any network manager will tell you that the Email is the most important network application . Email remains as the oldest and still the most frequently used network communications in the Internet.

15. Screenshots of Email Software Microsoft’s Outlook Mozilla Thunderbird

16. Other Network Applications Besides Web Browser, Instant Messaging & Email, there are other network applications that do: File transfer (Ws_FTP, Free Download Manager) Remote login (PuTTY, Terra Term) Accessing remote database (SQuirreL SQL Client ) Internet Relay Chat (mIRC) and other …

17. File Transfer W S _FTP Download Manager

18. Remote Login PuTTY, Tera Term, etc

19. Accessing Remote Database SQuirreL SQL Client

20. Internet Relay Chat (IRC) mIRC (precursor of Instant Messenger)

21. Question What do all these network applications have in common? – What common features do all these network application share?

22. A n s w er In general, these network applications share a common feature among themselves, which is accessing some form of remote information or resources . For example: Firefox is accessing a web site for web pages. Outlook is retrieving emails for a “inbox” Skype has to gain access to your “list of friends” via login. Download Managers are used to download movies from some “file sites.” Play online games “ Dota 2 ” via a “networked game world”. Remote = located far away from you These network applications can be technically called as network client software .

23. Network Client Software The main function of network client software is to access the resource/information in the network/Internet known as network services . All these so-called “network services” are located “somewhere” in the network or Internet. Do you know or care where is www.cnn.com or www. help.edu . my ? Network client software CAN’T exist WITHOUT network services. Network clients have to talk to network services. Client-server HAVE to work in pair. Known as client-server communication, which is 99% of today’s Internet traffic. Client software can’t communicate with other client software. You can’t use Web browser to talk directly to another browser. Instant messaging has to communicate via a server. Like all software applications, all network client software come in two forms: Command-line & GUI (graphic-user interface)

24. Clients in a Simple Network Visually, clients are PCs/workstations, linked to a connectivity device, which forms a network, accessing to remote resources or information in a server, as shown in the following network diagram.

25. A More Complex Client/Server Network

26. Clients & Workstation client A computer on the network that requests resources or services from another computer on a network. The term client may also refer to the user of a client workstation or a client software application installed on the workstation. client/server architecture A network design in which clients (typically desktop or laptop computers) use a centrally administered server to share data, data storage space, and devices. client/server network A network that uses centrally administered computers, known as servers, to enable resource sharing for and to facilitate communication between the other computers on the network. workstation A computer that runs a desktop operating system and connects to a network.

27. Networks, LAN, WAN & Internet network A group of computers and other devices (such as printers) that are connected by and can exchange data via some type of transmission media, such as a cable, a wire, or the atmosphere. LAN (local area network) A network of computers and other devices that is confined to a relatively small space, such as one building or even one office. WAN (wide area network) A network that spans a long distance and connects two or more LANs. Internet A complex WAN that connects LANs and clients around the globe.

28. Review: Network Client Software in Your PC Web Browsing: Firefox, Internet Explorer, Opera E-mail: Outlook, Thunderbird Instant messaging: MSN Messenger, Skype, ICQ, MIRC Video and audio streaming: Real player, Window Media Player, iTune Internet telephone: Skype Real-time video conference Skype, live messager,

29. Network Services Introducing some common types of network services, & the concept of client-server networks

30. Network Services and Server Network services provide remote software resources support to the network clients Network services are normally reside in network servers. Network services = software Network servers = hardware (PC) Clients of different operating systems (MAC or Windows) access the same services of the same server PC or MAC can read the same web page. Network services are “platform independent”. (Linux or Windows or Sun) Network is the “middle-man” that give communication links between servers and clients.

31. Data and Information Servers in your life When you read cnn.com, you’re communicating with a web server. When you read your yahoo.com mail, you’re communicating with a mail server (together with a web server). When you downloading files from Internet, you’re communicating with a file server. When you’re using msn, or skype, there is a server behind “coordinating” your communication. When you login to a msn messenger, you’re communicating with a Instant Messenger server. Through the server, you message is then relayed your friend who is online. When you’re playing massively multiplayer online role- playing game, MMORPG (e.g Perfect World) you’re communicating with a game server. When you’re watching on-line video (youtube) you’re communicating with a video streaming server.

32. Server and Client - 1 Server (Review) A computer on the network that manages shared network resources. Usually a more powerful computer with more RAM, Disk Space and Processing Power usually but not necessary Client (Review) A computer on the network requests services from another computer on a network. Servers provide services Clients request services Servers runs on a different set of software than the clients. 1 server (or PC) can provide many services.

33. Client & Server - 2 All client software communicate with server When you are using a web browser, your PC acts as a network client. Main task of client software is to “request” service from server Clients (web browser) get services (web pages) from servers (web sites). Client software don’t communicate with other client software directly. Client software communicate with other client software via servers Mail server, Instant Messenger server This type of servers acts as a “middle-man” between the clients. User of PC1 sends a mail to user of PC0 (stored in mail server) User of PC0 reads the mail at the mail server

34. Differences between Server & Client Servers normally runs 24 hours / 7 days. Clients are “normally” switched off once the users are gone. Servers runs “independently” once configured. Clients runs “dependently” with human users. Servers can have 1 monitor, 1 keyboard and 1 mouse connected to multiple CPUs (coordinated via KVM switch) Clients have 1 (sometimes 2) monitor, 1 keyboard, and 1 mouse with 1 CPU. Server software always “listens” Client software sends “request” to server on demand. Lastly, servers and clients run on different set of software Server’s software normally runs in the “background”

35. Two Categories of Servers Data and Information Server Providing data and information Pure data server (web server, file server) When you just read and download only. “Middle-man” servers (email server, newsgroup server, instant messenger) When writing and uploading are involved Networking Server Helping out in the network The client side will normally be the operating system (e.g. Windows XP, Linux) DNS server, DHCP server, print server

36. Some Common Servers Web Server (data and middle-man) Providing web pages Mail Server (data and middle-man) Storing and send emails File Server (data and middle-man) Downloading and uploading files Print Server (networking) Managing print queue jobs Database Server (data and middle-man) Providing necessary data to clients DNS Server [domain name server] (networking) Managing corresponding network address with domain name DHCP Server [dynamic hosts control protocol] (networking) Supply IP addresses to PCs with dynamic IP option Proxy Server (data and networking) Acts as an intermediary between external and internal networks, screening all incoming and outgoing data traffic Newsgroup Server (data and middle-man) Managing newsgroup

37. Servers and KVM switch KVM switch = K eyboard, V ideo, M ouse switch KVM switch is used to connect multiple CPUs to share 1 set of keyboard, monitor and mouse. Cost saving to configure servers (CPUs) with just 1 set of mouse, monitor & keyboard. Save space too.

38. Server Software : XAMPP You can download it from https://www.apachefriends.org/download.html Store your web page in assigned directory and start the service – Once you start the service, Apache runs at the “background”.

39. Some final notes on server & client A server can be client at the same time. You install XAMPP package in your PC, configure it and store your web page. You can still use your PC to surf the web (as long as you have the web browser) Outsider access your web page at the “background” of PC (meaning without your knowledge unless you check for it). A server can run different services at the same time. A client PC can communicate with different servers (or services) at the same time. You open Firefox, Outlook, Skype, while playing MMORPG However, A client program can normally talk to a type network service at any given time. You open Firefox to access web page but not remote login. You open Firefox to access a file server but not a web server at the same time.

40. Other terms in Client/Server Network Host A computer that enables resource sharing by other computers on the same network Node A client, server, or other device that can communicate over a network and that is identified by a unique number, known as its network address Segment A part of a network. Usually, a segment is composed of a group of nodes that use the same communications channel for all their traffic.

41. Q u i z Some questions to help your memory and understanding

42. True/False Questions Server must run on better PC than client. Client always listens to request. A client PC can provide network services. A Windows 10 laptop can be configured as both client and server. Client program has to be run at the “foreground” interfacing with human. A web server can’t be a print server at the PC. A client program can talk to multiple network services simutenously. Client program can’t communicate with another similar client program directly. Server program normally runs at the background without much interaction with user. A dns server and a dhcp server have to be on different machine/PC.