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Application layer

April 18, 2024

An application layer is an abstraction layer that specifies the shared communication protocols and interface methods used by hosts in a communications network.[1] An application layer abstraction is specified in both the Internet Protocol Suite (TCP/IP) and the OSI model.[2] Although both models use the same term for their respective highest-level layer, the detailed definitions and purposes are different.[3]

Internet protocol suite edit

In the Internet protocol suite, the application layer contains the communications protocols and interface methods used in process-to-process communications across an Internet Protocol (IP) computer network.[4] The application layer only standardizes communication and depends upon the underlying transport layer protocols to establish host-to-host data transfer channels and manage the data exchange in a client–server or peer-to-peer networking model.[5] Though the TCP/IP application layer does not describe specific rules or data formats that applications must consider when communicating, the original specification (in RFC 1123) does rely on and recommend the robustness principle for application design.[6][7]

OSI model edit

In the OSI model, the definition of the application layer is narrower in scope.[9] The OSI model defines the application layer as only the interface responsible for communicating with host-based and user-facing applications.[10] OSI then explicitly distinguishes the functionality of two additional layers, the session layer and presentation layer, as separate levels below the application layer and above the transport layer. OSI specifies a strict modular separation of functionality at these layers and provides protocol implementations for each. In contrast, the Internet Protocol Suite compiles these functions into a single layer.[10]

Sublayers edit

Originally the OSI model consisted of two kinds of application layer services with their related protocols.[11] These two sublayers are the common application service element (CASE) and specific application service element (SASE).[12] Generally, an application layer protocol is realized by the use of the functionality of a number of application service elements.[13] Some application service elements invoke different procedures based on the version of the session service available.[14]

CASE edit

The common application service element sublayer provides services for the application layer and request services from the session layer. It provides support for common application services, such as:

SASE edit

The specific application service element sublayer provides application-specific services (protocols), such as:

  • FTAM (File Transfer, Access and Manager)
  • VT (Virtual Terminal)
  • MOTIS (Message Oriented Text Interchange Standard)
  • CMIP (Common Management Information Protocol)
  • JTM (Job Transfer and Manipulation)[15]
  • MMS (Manufacturing Messaging Specification)
  • RDA (Remote Database Access)
  • DTP (Distributed Transaction Processing)

Protocols edit

The IETF definition document for the application layer in the Internet Protocol Suite is RFC 1123. It provided an initial set of protocols that covered the major aspects of the functionality of the early Internet:[6]

Examples edit

Additional notable application-layer protocols include the following:

References edit

  1. ^ "Application Layer | Layer 7". The OSI-Model. Retrieved November 5, 2019.
  2. ^ "Four Layers of TCP/IP model, Comparison and Difference between TCP/IP and OSI models". www.omnisecu.com. Retrieved November 5, 2019.
  3. ^ "What is the difference between TCP/IP and IP protocol?". SearchNetworking. Retrieved November 5, 2019.
  4. ^ "What is the difference between TCP/IP and IP protocol?". SearchNetworking. Retrieved November 5, 2019.
  5. ^ SEO, Bradley Mitchell An MIT graduate who brings years of technical experience to articles on; computers; Networking, Wireless. "What Is Transmission Control Protocol/Internet Protocol (TCP/IP)?". Lifewire. Retrieved November 5, 2019.
  6. ^ a b Robert Braden, ed. (October 1989). "RFC 1123: Requirements for Internet Hosts – Application and Support". Network Working Group of the IETF.
  7. ^ "What is the Application Layer?". www.tutorialspoint.com. Retrieved November 5, 2019.
  8. ^ "X.225 : Information technology – Open Systems Interconnection – Connection-oriented Session protocol: Protocol specification". from the original on February 1, 2021. Retrieved March 10, 2023.
  9. ^ Shaw, Keith (October 22, 2018). "The OSI model explained: How to understand (and remember) the 7 layer network model". Network World. Retrieved November 5, 2019.
  10. ^ a b "What Is The OSI Model?". CloudFlare. 2019. Retrieved November 4, 2019.
  11. ^ "Application Layer (Layer 7 of the OSI Model)". September 2, 2019.
  12. ^ a b Hura, Gurdeep (2001). "Application Layer". Data and Computer Communications: Networking and Internetworking. CRC Press LLC. pp. 710–712. ISBN 9780849309281.
  13. ^ Warrier, U.S.; Besaw, L. (April 1989). Common Management Information Services and Protocol over TCP/IP (CMOT) (Report). doi:10.17487/RFC1095.
  14. ^ Rose, Marshall T. (December 1988). "ISO presentation services on top of TCP/IP based internets".
  15. ^ a former OSI standard[permanent dead link]

External links edit

  •   Media related to Application layer protocols at Wikimedia Commons
  •   Learning materials related to Application layer at Wikiversity

April 18, 2024
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An application layer is an abstraction layer that specifies the shared communication protocols and interface methods used by hosts in a communications network 1 An application layer abstraction is specified in both the Internet Protocol Suite TCP IP and the OSI model 2 Although both models use the same term for their respective highest level layer the detailed definitions and purposes are different 3 Contents 1 Internet protocol suite 2 OSI model 2 1 Sublayers 2 1 1 CASE 2 1 2 SASE 3 Protocols 3 1 Examples 4 References 5 External linksInternet protocol suite editIn the Internet protocol suite the application layer contains the communications protocols and interface methods used in process to process communications across an Internet Protocol IP computer network 4 The application layer only standardizes communication and depends upon the underlying transport layer protocols to establish host to host data transfer channels and manage the data exchange in a client server or peer to peer networking model 5 Though the TCP IP application layer does not describe specific rules or data formats that applications must consider when communicating the original specification in RFC 1123 does rely on and recommend the robustness principle for application design 6 7 OSI model editIn the OSI model the definition of the application layer is narrower in scope 9 The OSI model defines the application layer as only the interface responsible for communicating with host based and user facing applications 10 OSI then explicitly distinguishes the functionality of two additional layers the session layer and presentation layer as separate levels below the application layer and above the transport layer OSI specifies a strict modular separation of functionality at these layers and provides protocol implementations for each In contrast the Internet Protocol Suite compiles these functions into a single layer 10 Sublayers edit Originally the OSI model consisted of two kinds of application layer services with their related protocols 11 These two sublayers are the common application service element CASE and specific application service element SASE 12 Generally an application layer protocol is realized by the use of the functionality of a number of application service elements 13 Some application service elements invoke different procedures based on the version of the session service available 14 CASE edit The common application service element sublayer provides services for the application layer and request services from the session layer It provides support for common application services such as ACSE Association Control Service Element 12 ROSE Remote Operation Service Element CCR Commitment Concurrency and Recovery RTSE Reliable Transfer Service Element SASE edit The specific application service element sublayer provides application specific services protocols such as FTAM File Transfer Access and Manager VT Virtual Terminal MOTIS Message Oriented Text Interchange Standard CMIP Common Management Information Protocol JTM Job Transfer and Manipulation 15 MMS Manufacturing Messaging Specification RDA Remote Database Access DTP Distributed Transaction Processing Protocols editThe IETF definition document for the application layer in the Internet Protocol Suite is RFC 1123 It provided an initial set of protocols that covered the major aspects of the functionality of the early Internet 6 Hypertext documents Hypertext Transfer Protocol HTTP Remote login to hosts Telnet Secure Shell File transfer File Transfer Protocol FTP Trivial File Transfer Protocol TFTP Electronic mail transport Simple Mail Transfer Protocol SMTP Networking support Domain Name System DNS Host initialization BOOTP Remote host management Simple Network Management Protocol SNMP Common Management Information Protocol over TCP CMOT Examples edit Additional notable application layer protocols include the following 9P Plan 9 from Bell Labs distributed file system protocol AFP Apple Filing Protocol APPC Advanced Program to Program Communication AMQP Advanced Message Queuing Protocol Atom Publishing Protocol BEEP Block Extensible Exchange Protocol Bitcoin BitTorrent CFDP Coherent File Distribution Protocol CoAP Constrained Application Protocol DDS Data Distribution Service DeviceNet DNS Domain Name Services eDonkey ENRP Endpoint Handlespace Redundancy Protocol FastTrack KaZaa Grokster iMesh Finger User Information Protocol Freenet FTAM File Transfer Access and Management FTP File Transfer Protocol Gemini Gemini protocol Gopher Gopher protocol HL7 Health Level Seven HTTP Hypertext Transfer Protocol Hypercore formerly dat H 323 Packet Based Multimedia Communications System IMAP Internet Message Access Protocol IRC Internet Relay Chat IPFS InterPlanetary File System Kademlia LDAP Lightweight Directory Access Protocol LPD Line Printer Daemon Protocol MIME S MIME Multipurpose Internet Mail Extensions and Secure MIME Modbus MQTT Protocol Netconf NFS Network File System NIS Network Information Service NNTP Network News Transfer Protocol NTCIP National Transportation Communications for Intelligent Transportation System Protocol NTP Network Time Protocol OSCAR AOL Instant Messenger Protocol POP Post Office Protocol PNRP Peer Name Resolution Protocol RDP Remote Desktop Protocol RELP Reliable Event Logging Protocol RFB Remote Framebuffer Protocol Rlogin Remote Login in UNIX Systems RPC Remote Procedure Call RTMP Real Time Messaging Protocol RTP Real time Transport Protocol RTPS Real Time Publish Subscribe RTSP Real Time Streaming Protocol SAP Session Announcement Protocol SDP Session Description Protocol SIP Session Initiation Protocol SLP Service Location Protocol SMB Server Message Block SMTP Simple Mail Transfer Protocol SNTP Simple Network Time Protocol SSH Secure Shell SSMS Secure SMS Messaging Protocol TCAP Transaction Capabilities Application Part TDS Tabular Data Stream Tor anonymity network Tox TSP Time Stamp Protocol VTP Virtual Terminal Protocol Whois and RWhois Remote Directory Access Protocol WebDAV WebRTC WebSocket X 400 Message Handling Service Protocol X 500 Directory Access Protocol DAP XMPP Extensible Messaging and Presence Protocol Z39 50References edit Application Layer Layer 7 The OSI Model Retrieved November 5 2019 Four Layers of TCP IP model Comparison and Difference between TCP IP and OSI models www omnisecu com Retrieved November 5 2019 What is the difference between TCP IP and IP protocol SearchNetworking Retrieved November 5 2019 What is the difference between TCP IP and IP protocol SearchNetworking Retrieved November 5 2019 SEO Bradley Mitchell An MIT graduate who brings years of technical experience to articles on computers Networking Wireless What Is Transmission Control Protocol Internet Protocol TCP IP Lifewire Retrieved November 5 2019 a b Robert Braden ed October 1989 RFC 1123 Requirements for Internet Hosts Application and Support Network Working Group of the IETF What is the Application Layer www tutorialspoint com Retrieved November 5 2019 X 225 Information technology Open Systems Interconnection Connection oriented Session protocol Protocol specification Archived from the original on February 1 2021 Retrieved March 10 2023 Shaw Keith October 22 2018 The OSI model explained How to understand and remember the 7 layer network model Network World Retrieved November 5 2019 a b What Is The OSI Model CloudFlare 2019 Retrieved November 4 2019 Application Layer Layer 7 of the OSI Model September 2 2019 a b Hura Gurdeep 2001 Application Layer Data and Computer Communications Networking and Internetworking CRC Press LLC pp 710 712 ISBN 9780849309281 Warrier U S Besaw L April 1989 Common Management Information Services and Protocol over TCP IP CMOT Report doi 10 17487 RFC1095 Rose Marshall T December 1988 ISO presentation services on top of TCP IP based internets a former OSI standard permanent dead link External links edit nbsp Media related to Application layer protocols at Wikimedia Commons nbsp Learning materials related to Application layer at Wikiversity Retrieved from https en wikipedia org w index php title Application layer amp oldid 1218812441, wikipedia, wiki, book, books, library,

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