OSI Application Protocol Layer

An OSI Application Protocol Layer is an abstraction layer that specifies shared communication protocols and interface methods for enabling network hosts to exchange application data.

• Context:
  • It can implement Network Protocol through application protocols.
  • It can provide Interface Method through protocol handlers.
  • It can support Host Communication through service endpoints.
  • It can enable Data Exchange through network services.
  • It can manage Resource Access through access controls.
  • It can ensure Device Identification through discovery protocols.
  • It can validate Network Interface through interface checkers.
  • It can maintain Data Integrity through error recoverys.
  • ...
  • It can often handle Session Management through connection handlers.
  • It can often control Data Flow through flow controls.
  • It can often ensure Message Integrity through error checkings.
  • It can often maintain Service Quality through performance monitors.
  • It can often provide Authentication Service through security protocols.
  • ...
  • It can range from being a Simple Protocol Layer to being a Complex Protocol Layer, depending on its protocol complexity.
  • It can range from being a Basic Service Layer to being an Advanced Service Layer, depending on its service capability.
  • It can range from being a TCP/IP Model Layer to being an OSI Model Layer, depending on its architectural model.
  • ...
  • It can integrate with Transport Layer for reliable delivery.
  • It can work with Presentation Layer for data formatting.
  • It can interact with Session Layer for connection management.
  • ...
• Examples:
  • Service Implementation Types, such as:
    • Common Application Service Elements, such as:
      • Remote Operation Services for distributed operations.
      • Data Transfer Services for data movement.
    • Specific Application Service Elements, such as:
      • File Transfer Services for file operations.
      • Database Access Services for data retrieval.
  • Protocol Implementations, such as:
    • Web Protocols, such as:
      • HTTP Protocol for web communication.
      • HTTPS Protocol for secure web communication.
    • File Transfer Protocols, such as:
      • FTP Protocol for file transfer.
      • SFTP Protocol for secure file transfer.
    • Email Protocols, such as:
      • SMTP Protocol for email transmission.
      • POP3 Protocol for email retrieval.
  • Network Services, such as:
    • Directory Services, such as:
      • DNS Service for name resolution.
      • LDAP Service for directory access.
    • Authentication Services, such as:
      • Kerberos Service for network authentication.
      • OAuth Service for authorization protocol.
  • ...
• Counter-Examples:
  • Transport Layer, which manages data transmission but not application logic.
  • Network Layer, which handles packet routing but not application services.
  • Data Link Layer, which controls physical transmission but not application protocols.
• See: OSI Model, Abstraction Layer, Communication Protocol, Interface (Computing), Host (Network), Internet Protocol Suite.

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References

2025

• (Wikipedia, 2025) ⇒ https://en.wikipedia.org/wiki/application_layer Retrieved:2025-1-29.
  • An application layer is an abstraction layer that specifies the shared communication protocols and interface methods used by hosts in a communications network. An application layer abstraction is specified in both the Internet Protocol Suite (TCP/IP) and the OSI model. Although both models use the same term for their respective highest-level layer, the detailed definitions and purposes are different.

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