Application Layer : Client Server Model, Socket Interface, Domain Name System (DNS): Electronic Mail (SMTP) and file transfer (FTP) HTTP and WWW. Utah University ; 1971 first email program ; 1974 TCP/IP ; 1980s Local Area Networks (LANs) 1984 OSI Layer ; 1990s WWW / Internetworking; 3 Why Networking? lecture 23 network management and performance. It is the top most layer of OSI Model. Number; Simple Teacher Format; WiFi. CS 408 Computer Networks - Text: computer networks with internet technology by william stallings chapter 1 - data, CS 408 Computer Networks - . material. DNS services hostname to IP address translation host aliasing Aliases, where canonical name is real name mail server aliasing load distribution replicated Web servers: set of IP addresses for one name DNS, Root DNS Servers org DNS servers edu DNS servers com DNS servers poly.edu DNS servers umass.edu DNS servers pbs.org DNS servers yahoo.com DNS servers amazon.com DNS servers Distributed, Hierarchical Database Client wants IP for www.amazon.com; 1st approx: client queries a root server to find .comDNS server client queries .com DNS server to get amazon.com DNS server client queries amazon.com DNS server to get IP address for www.amazon.com, Contacted by local name server that can not resolve name Root name server: Contacts authoritative name server if name mapping not known Gets mapping Returns mapping to local name server DNS: Root Name Servers a Verisign, Dulles, VA c Cogent, Herndon, VA (also LA) d U Maryland College Park, MD g US DoD Vienna, VA h ARL Aberdeen, MD j Verisign, ( 21 locations) k RIPE London (also 16 other locations) i Autonomica, Stockholm (plus 28 other locations) m WIDE Tokyo (also Seoul, Paris, SF) e NASA Mt View, CA f Internet Software C. Palo Alto, CA (and 36 other locations) 13 root name servers worldwide b USC-ISI Marina del Rey, CA l ICANN Los Angeles, CA, 2022 SlideServe | Powered By DigitalOfficePro, Application Layer CS 3516 Computer Networks, - - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -. Networking: A Top Jim Kurose, Keith Ross Instant access to millions of ebooks, audiobooks, magazines, podcasts and more. This layer allows users to send data, access data and use networks. This layer allows users to access, retrieve and manage files in a remote computer. Throughput some apps (e.g., multimedia) require minimum amount of throughput to be effective other apps (elastic apps) make use of whatever throughput they get Security encryption, data integrity, , Transport Service Requirements of Common Apps Time Sensitive no no no yes, 100s msec yes, few secs yes, 100s msec yes and no Application file transfer e-mail Web documents real-time audio/video stored audio/video interactive games instant messaging Throughput elastic elastic elastic audio: 5kbps-1Mbps video:10kbps-5Mbps same as above few kbps up elastic Data loss no loss no loss no loss loss-tolerant loss-tolerant loss-tolerant no loss, TCP service: connection-oriented: setup required between client and server processes reliable transport between sending and receiving process flow control: sender wont overwhelm receiver congestion control: throttle sender when network overloaded does not provide: timing, minimum throughput guarantees, security UDP service: unreliable data transfer between sending and receiving process does not provide: connection setup, reliability, flow control, congestion control, timing, throughput guarantee, or security Q: why bother? So you do not need to waste the time on rewritings. All the important points related to a particular topic of Computer Networks are jotted down in small paragraphs. APPLICATION LAYER Efficiency and Productivity ; Reliability ; Student at Daffodil International University. The network architecture is fixed and provides a set of services to applications. AI and Machine Learning Demystified by Carol Smith at Midwest UX 2017, Pew Research Center's Internet & American Life Project, Harry Surden - Artificial Intelligence and Law Overview. Clipping is a handy way to collect important slides you want to go back to later. Click here to review the details. Reduce response time for client request Reduce traffic on an institutions access link. The SlideShare family just got bigger. there are two forms of. 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It is a protocol used to access the data on the World Wide Web (www). lecture 8 layer 1 physical layer. www.someschool.edu/someDept/pic.gif path name host name Web and HTTP First some jargon Web page consists of objects Object can be HTML file, JPEG image, Java applet, audio file, Web page consists of base HTML-file which includes several referenced objects Each object is addressable by a URL Example URL: HTTP: hypertext transfer protocol Webs application layer protocol client/server model client: browser that requests, receives, displays Web objects server: Web server sends objects in response to requests HTTP Overview HTTP request PC running Explorer HTTP response HTTP request Server running Apache Web server HTTP response Mac running Navigator, Uses TCP: client initiates TCP connection (creates socket) to server, port 80 server accepts TCP connection from client HTTP messages (application-layer protocol messages) exchanged between browser (HTTP client) and Web server (HTTP server) TCP connection closed HTTP is stateless server maintains no information about past client requests HTTP Overview (continued) aside Protocols that maintain state are complex! Some services provided by this layer includes: E-Mail, transferring files, distributing the results to user, directory services, network . We label one of the two processes as the client and another process as the server. The application layer programs are based on client and servers. DNS, HTTP, FTP are the common examples of application layer. of computer science columbia university, CS 408 Computer Networks - . aditya akella lecture 6 - error/flow control & intro to switching and medium access, CS 453 Computer Networks - . CCNA 1 Routing and Switching v5.0 Chapter 10, Jaimin chp-7 - application layer- 2011 batch, Chapter 2 - Computer Networking a top-down Approach 7th. HTTP server at host www.someSchool.edu waiting for TCP connection at port 80. A server is fixed, well-known address known as IP address because the server is always on while the client can always contact the server by sending a packet to the sender's IP address. Developed by JavaTpoint. HTTP client receives response message containing html file, displays html. Persistent HTTP Multiple objects can be sent over single TCP connection between client and server. It appears that you have an ad-blocker running. HTTP connections, Suppose user enters URL www.someSchool.edu/someDepartment/home.index 1a. ebay 8734 usual http request msg Amazon server creates ID 1678 for user usual http response Set-cookie: 1678 create entry ebay 8734 amazon 1678 ebay 8734 amazon 1678 usual http request msg cookie: 1678 access cookie- specific action usual http response msg usual http response msg access usual http request msg cookie: 1678 cookie- spectific action Cookies: keeping state (cont.) Algorithms Factor Applications Discrete Impact; data link protocols. Example: -Web application consists of many components, including a standard for document formats (e.g. UDP. Department of Computer Engineering, Trains. You can read the details below. March 2012 We've updated our privacy policy. Therefore, we can say that a process can both download and upload the files. karim el defrawy donald bren school of information and computer, CS 640: Computer Networks - . CCNA 1 Routing and Switching v5.0 Chapter 10, Chapter 2 - Computer Networking a top-down Approach 7th, Slides for protocol layering and network applications, Khulna University of Engineering & Technology (KUET), Hypertexttransferprotocolhttp 131012171813-phpapp02, multi threaded and distributed algorithms, Irresistible content for immovable prospects, How To Build Amazing Products Through Customer Feedback. AISSMS COE ,Pune. Mail us on [emailprotected], to get more information about given services. dr. clincy professor of cs. It addresses all four major architectural layers of modern computer networks (application layer, transport layer, network layer and link layer), as well as selected topics from multimedia networking, wireless networking and network security. PPT of Application Layer PPT is a short and the most convenient way to understand a chapter. fApplication Layer - Provides the interface between the applications on either end of the network. SMTP B.) The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. www.HelpWriting.net This service will write as best as they can. what is deterlab?. A note on the use of these ppt slides: chapter goals: understand principles behind, CS 283 Computer Networks - . Ross, All Rights Reserved. Computer In return for use, we only learn about protocols by examining popular application-level protocols HTTP FTP, Application LayerCS 3516 Computer Networks, Goals: conceptual, implementation aspects of network application protocols transport-layer service models client-server paradigm peer-to-peer paradigm learn about protocols by examining popular application-level protocols HTTP FTP SMTP / POP3 / IMAP DNS programming network applications socket API Chapter 2: Application Layer, e-mail web instant messaging remote login P2P file sharing multi-user network games streaming stored video clips social networks voice over IP real-time video conferencing grid computing Some network apps, Write programs that run on (different) end systems communicate over network e.g., web server software communicates with browser software No need to write software for network-core devices Network-core devices do not run user applications applications on end systems allows for rapid app development, propagation application transport network data link physical application transport network data link physical application transport network data link physical Creating a Network App, 2.1 Principles of network applications 2.2 Web and HTTP 2.3 FTP 2.4 Electronic Mail SMTP, POP3, IMAP 2.5 DNS 2.6 P2P applications 2.7 Socket programming with UDP 2.8 Socket programming with TCP Chapter 2: Application layer, Application architectures Client-server (CS) Including data centers / cloud computing Peer-to-peer (P2P) Hybrid of client-server and P2P, client/server Client-server Architecture server: always-on host permanent IP address server farms for scaling clients: communicate with server may be intermittently connected may have dynamic IP addresses do not communicate directly with each other, Server Example - Google Data Centers Estimated cost of data center: $600M Google spent $2.4B in 2007 on new data centers Each data center uses 50-100 megawatts of power, peer-peer Pure P2P Architecture no always-on server arbitrary end systems directly communicate peers are intermittently connected and change IP addresses Highly scalable but difficult to manage, Hybrid of Client-server and P2P E.g. clearly, users of, CS 453 Computer Networks - . In the development of this networking . Introduction to Computer Networks 1.1 Data Communicatio n:When we communicate, we are sharing in formation. A network application consists of a pair of processes that send the messages to each other over a network. chapter 14 : data link control. (after all, wed like people to use our book!) Weve updated our privacy policy so that we are compliant with changing global privacy regulations and to provide you with insight into the limited ways in which we use your data. announcements. tv cable as a network media wifi wimax. so far, our communications, CS 453 Computer Networks - . Application Layer CS 3516 - Computer Networks. request rate from institutions browsers to origin servers = 15/sec delay from institutional router to any origin server and back to router = 2 sec Consequences utilization on LAN = 15% utilization on access link = 100% total delay = Internet delay + access delay + LAN delay = 2 sec + minutes (congested) + milliseconds Caching Example origin servers public Internet 15 Mbps access link institutional network 100 Mbps LAN institutional cache, possible solution increase bandwidth of access link to, say, 100 Mbps consequence utilization on LAN = 15% utilization on access link = 15% Total delay = Internet delay + access delay + LAN delay = 2 sec + msecs + msecs BUToften a costly upgrade Caching Example (cont) origin servers public Internet 100 Mbps access link institutional network 100 Mbps LAN institutional cache, possible solution: install cache suppose hit rate is 0.4 consequence 40% requests will be satisfied almost immediately 60% requests satisfied by origin server utilization of access link reduced to 60%, resulting in negligible delays (say 10 msec) total avg delay = Internet delay + access delay + LAN delay = .6*(2.01) secs + .4*milliseconds < 1.4 secs Caching example (cont) origin servers public Internet 15 Mbps access link institutional network 100 Mbps LAN institutional cache, Goal: dont send object if cache has up-to-date cached version cache: specify date of cached copy in HTTP request If-modified-since:
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