Fact-checked by Grok 2 weeks ago

Session layer

The Session layer, also known as Layer 5 of the Open Systems Interconnection (OSI) , is responsible for establishing, managing, and terminating communication sessions between applications running on different end-user devices, enabling coordinated exchange over a . Defined in the ISO/IEC 7498-1 standard as the layer that provides the means for cooperating entities to organize and synchronize their communication, it acts as an intermediary between the (Layer 4) and the (Layer 6), ensuring that sessions maintain a logical for the duration of the interaction. This layer handles key functions such as dialogue control to manage the flow and direction of communication (e.g., half-duplex or full-duplex modes), through checkpoints to allow from interruptions by resuming from the last checkpoint, avoiding retransmission of unaffected segments, and session with mechanisms to verify participants at the outset. In practice, the Session layer organizes transport-layer data streams into coherent sessions with defined start and end points, conserving bandwidth and resources by keeping connections open only as needed and closing them efficiently upon completion. It supports the multiplexing of multiple independent data streams—such as combining audio and video in real-time applications—into a single managed session, which is essential for protocols like the used in VoIP and multimedia communications. Other notable protocols operating at this layer include for local area network name resolution and session management, (RPC) for distributed computing, and (PPTP) for virtual private networks, though in the / model, many Session layer functions are integrated into the rather than maintained as a distinct entity. By providing these services, the Session layer ensures fault-tolerant, orderly interactions that abstract away lower-layer complexities for higher-level applications.

Overview

Definition and Role

The session layer, designated as layer 5 in the Open Systems Interconnection (OSI) reference model, is responsible for establishing, managing, and terminating communication sessions between cooperating applications running on different hosts. This layer enables applications to engage in coordinated, ongoing interactions across a network, treating each session as a semi-permanent dialogue that facilitates structured data exchange. Introduced as part of the , which was finalized and published by the (ISO) in 1984 under ISO 7498, the session layer provides a standardized framework for session coordination without delving into lower-level transmission details. In its core role, the session layer serves as an intermediary between the (layer 6) above it and the (layer 4) below, focusing exclusively on session services such as , , and orderly of application-level connections. Unlike the , which handles data formatting and syntax, or the , which ensures reliable end-to-end delivery, the session layer does not manage data representation or error correction; instead, it coordinates the dialogue between applications to support seamless communication. This positioning allows it to abstract session management from the underlying transport mechanisms, briefly interacting with the to leverage existing connections for session support. Key concepts of the session layer include the notion of a session as a logical, application-oriented designed for persistent data exchange, which distinguishes it from the more host-centric connections by incorporating application-specific features like and . It supports mechanisms such as remote procedure calls (RPCs), enabling applications to invoke functions on remote systems as if they were local, and dialog to control the flow and synchronization of interactions between endpoints. These elements ensure that sessions can recover from interruptions and maintain integrity, adding a layer of tailored to application needs beyond mere .

Position in OSI Model

The Session layer, designated as layer 5 in the Open Systems Interconnection (OSI) reference model, occupies the fifth position among the seven conceptual layers defined by the (ISO). This model, formalized in ISO/IEC 7498-1, structures network functions hierarchically to promote among diverse systems. Positioned immediately below the (layer 6), which focuses on data formatting, syntax, and , the Session layer receives processed data units from it to manage ongoing communications. Above the (layer 4), which ensures reliable end-to-end delivery, the Session layer relies on transport services for reliable transfer without direct involvement in lower-layer operations. In terms of interactions, the Session layer acts as an intermediary, accepting service data units from the and encapsulating them with session-specific control information before passing them downward to the via transport service data units. Conversely, it utilizes transport protocol data units received from layer 4 to reconstruct and deliver session-managed information upward to layer 6. The layer maintains strict boundaries, with no direct access or invocation of services from the underlying 3), 2), or 1) layers, ensuring in the OSI . This design allows the Session layer to focus exclusively on coordinating application-level dialogues without dependency on physical or details. The primary data unit employed by the Session layer is the Session Protocol Data Unit (SPDU), which incorporates headers for session , , and termination, along with points and dialog elements. SPDUs enable the layer to handle structured exchanges, such as full-duplex or half-duplex modes, while abstracting the complexities of data transport. As a conceptual construct rather than a rigidly implemented component, the OSI model's layers—including the Session layer—facilitate standardized descriptions of across implementations. Notably, the Session layer bridges the user-oriented upper layers (layers 5 through 7), which emphasize application-specific concerns, with the resource-oriented lower layers (layers 1 through 4), which manage connectivity and transmission, thereby enabling seamless integration in open systems environments.

Core Functions

Session Establishment and Termination

The session layer facilitates the establishment of communication sessions between applications by initiating a connection-oriented through the S-CONNECT primitive, which employs a CONNECT Session Protocol Data Unit (SPDU) to negotiate key parameters such as operational modes, token allocations for control, and supported functional units. This occurs between the session protocol machines (SPMs) of the communicating entities, allowing the initiator to propose parameters and the responder to accept, modify, or reject them via S-CONNECT response and confirm primitives. During establishment, the session layer may assign the new session to an existing suitable for reuse or create a fresh connection if none is available, optimizing resource use in multi-session environments. Once established, the session layer manages the ongoing session by maintaining state information, including variables like V(A) and V(R) to track data flow and activity, ensuring coordinated between the session service users (SS-users). It handles graceful degradation during transient failures by monitoring session activity and employing —via GIVE and PLEASE SPDUs—to regulate access to session functions, preventing conflicts and supporting orderly progression. This underpins reliable multi-turn dialogues, such as in where sessions enable repeated interactions without re-establishing lower-layer connections. Session termination proceeds orderly through the S-RELEASE and FINISH SPDU, allowing the SS-users to negotiate and confirm closure, thereby freeing allocated session and underlying transport resources. For abrupt endings, such as due to errors or timeouts, the layer invokes S-U-ABORT (user-initiated) or S-P-ABORT (provider-initiated) with ABORT SPDUs to immediately terminate the session, followed by optional mechanisms. The supports major and minor points to enable partial during termination-related disruptions, resetting the session to a prior stable state without full re-establishment. In applications like OSI (), session establishment negotiates parameters to support multiple remote invocations over a persistent , enhancing for client-server interactions. Termination in such contexts ensures clean resource deallocation after procedure completion, aligning with the remote operations model for reliable distributed processing.

Dialog Control

Dialog control in the session layer of the manages the coordination and direction of data exchange between communicating applications during an established session, ensuring orderly and conflict-free communication. This function determines the mode of interaction, enforces rules for , and utilizes mechanisms to prevent simultaneous transmissions that could lead to data collisions, particularly in multi-party or structured dialogues. The session layer supports three primary communication modes: simplex, half-duplex, and full-duplex. In mode, data flows in one direction only, from to without provision for reverse communication, suitable for broadcast-like scenarios. Half-duplex mode allows data transmission in both directions but only one way at a time, requiring strict alternation to avoid overlaps. Full-duplex mode enables simultaneous bidirectional data exchange, maximizing efficiency for applications needing concurrent input and output. These modes are negotiated and agreed upon by the applications during session establishment, where parameters such as duplex type are specified to align communication rules from the outset. To enforce these modes, especially in half-duplex scenarios, the session layer employs token management, where conceptual tokens grant exclusive rights to transmit . The token, for instance, is owned by one party at a time; only the token holder can initiate data transfer using Session Protocol Data Units (SPDUs) like DATA TRANSFER, while the other party must request the token via PLEASE TOKENS or await its transfer through GIVE TOKENS. In full-duplex mode, token restrictions on data sending are lifted, allowing unrestricted bidirectional flow. This token-based approach ensures and prevents conflicts by serializing access to the . For more complex sessions involving multiple activities or participants, activity tokens extend this control under the activity management functional unit. These tokens manage the lifecycle of distinct activities within a session—starting with ACTIVITY START and ending with ACTIVITY END SPDUs—ensuring that only authorized parties participate in specific dialogues without interfering with others. This mechanism is crucial for preventing collisions in multi-party sessions, such as collaborative applications, by scoping token ownership to individual activities.

Synchronization and Recovery

The session layer incorporates mechanisms to insert checkpoints during ongoing data exchanges, preserving the session state at defined points to enable from interruptions without full restarts. These synchronization points function as markers in the , often identified by serial numbers or timestamps, which record the progress of the and allow both communicating entities to maintain consistency. By saving this state information, the layer supports in extended interactions, preventing the loss of accumulated work in case of transient failures like network outages. Synchronization points are categorized as major or minor, each serving distinct roles in balancing continuity and reliability. Minor synchronization points provide lightweight checkpoints that permit transmission to proceed while an is pending, enabling efficient insertion into active flows without halting the session. synchronization points, however, enforce a stricter by suspending further until explicit , ensuring a more comprehensive that resets tokens and purges unconfirmed . These are implemented through dedicated Session Units (SPDUs), including the Minor Sync Point SPDU for minor points and the Sync Point SPDU for major points, both carrying serial numbers to track and reference specific locations in the session. Recovery from disruptions occurs via resynchronization primitives that allow the session to resume from the most recent acknowledged synchronization point, selectively retransmitting or discarding intervening data as needed. The Resynchronize SPDU initiates this procedure, specifying the target serial number and mode (such as restart, which clears prior data, or set, which retains it), followed by a Resynchronize ACK SPDU to confirm alignment. This approach supports granular recovery, limiting rollback to the last major sync point while leveraging minor points for finer control, thereby minimizing overhead in long-running sessions. Such capabilities are essential for applications like file transfers in the File Transfer, Access, and Management (FTAM) protocol, where resynchronization ensures partial completions can be salvaged during large-scale data movements.

Protocols and Implementations

OSI-Specific Protocols

The primary protocol operating at the OSI session layer is X.225, equivalently known as ISO/IEC 8327, which specifies the connection-oriented session protocol for establishing, managing, and terminating sessions between applications in open systems interconnection environments. This protocol defines a set of service that enable core session functions, including connection establishment via S-CONNECT , data transfer through S-DATA and S-EXPEDITED-DATA , orderly release with S-RELEASE , and abnormal termination using S-ABORT . These support half-duplex or full-duplex dialog , synchronization points for , and activity management to coordinate resource usage during sessions. Within the OSI session framework, kernel session functions provide a minimal set of operations essential for basic session management, mapping to the protocol's kernel functional unit that ensures for connection-oriented services. These include bind-like association setup (via S-CONNECT for session binding to transport connections), connect for initiating dialogues, data transfer primitives for reliable exchange, and abort for immediate session termination to handle errors or interruptions. The kernel avoids optional features like token management or minor synchronization, focusing on reliable establishment and teardown to support upper-layer applications without unnecessary overhead. ISO/IEC 8327 was first standardized by the in 1987 as part of the initial OSI protocol specifications, with amendments in 1997 incorporating efficiency enhancements and nested connection support. It played a foundational role in higher-level OSI applications, such as the message handling system for electronic mail transfer and the directory access protocol for global directory services, where session management ensured coordinated, recoverable interactions across distributed systems. Despite its comprehensive design, the protocol has rarely been implemented in standalone form due to the broader OSI suite's limited commercial adoption in favor of more practical approaches.

Non-OSI Protocols and Examples

provides session services for communication, particularly in Windows environments, where it enables reliable, connection-oriented transport between applications on separate computers. The session service handles session establishment, maintenance, and termination, including name resolution to identify hosts and setup of point-to-point connections for data exchange. This service operates over transport protocols like , abstracting session management to support legacy and printing in SMB/CIFS implementations. ONC RPC, or Open Network Computing Remote Procedure Call, facilitates session-like management for distributed procedure invocations across networks, allowing a client program to execute functions on a remote as if local. Defined in RFC 5531, ONC RPC establishes connections via underlying transport layers ( or ) and manages call sequences, including and error recovery, to maintain coherent remote interactions. It abstracts the session setup process, enabling stateless or stateful operations depending on the implementation, and is foundational in systems like NFS for file access. In networks, the Zone Information Protocol () operates at the session layer to manage zone mappings and maintain for Macintosh systems. coordinates the association of network numbers with logical zones, using queries and updates to propagate zone information across routers, ensuring applications can discover and connect to resources within specific zones. This protocol supports session establishment by providing a dynamic that aids in locating services without direct broadcasting. The (SCP), as outlined in early IETF drafts, enables multiple lightweight connections over a single stream for efficient dialogue control in networked applications. The (PPTP) provides session layer functions for establishing, managing, and terminating (VPN) connections, encapsulating (PPP) frames within datagrams to enable secure remote access. Defined in 2637, PPTP uses a TCP-based control channel on port 1723 for session negotiation, including , setup, and management of data tunnels via (GRE). The (), while primarily an application-layer signaling protocol per RFC 3261, performs session layer functions by initiating, modifying, and terminating multimedia sessions such as voice and video calls over IP networks. establishes end-to-end sessions through invite messages and supports features like synchronization points for long-running multimedia dialogues, though it relies on transport protocols for reliability.

Comparisons and Context

With TCP/IP Model

The TCP/IP model, consisting of four layers—network access, , , and application—lacks a dedicated session layer equivalent to that in the OSI model. Instead, session-related functions such as establishment, maintenance, and termination are primarily absorbed into the via protocols like , which provides connection-oriented communication through a three-way handshake to synchronize sequence numbers and establish reliable end-to-end byte streams. This integration simplifies the model by avoiding the overhead of a separate layer, prioritizing practical implementation over the OSI's conceptual granularity. However, TCP's capabilities differ from OSI session layer services; it ensures reliable delivery and flow but does not natively support dialog (e.g., half-duplex ) or explicit synchronization points for from application-level errors. These advanced features are instead implemented at the , where protocols simulate session —for instance, FTP maintains a persistent connection over for commands and replies while opening separate data connections for transfers, effectively emulating multi-activity sessions. Similarly, HTTP relies on stateful mechanisms like to track user sessions across stateless requests, enabling persistence without inherent transport-layer support. This distribution reflects /IP's design philosophy of efficiency and minimal layering, which has facilitated widespread adoption despite forgoing the OSI session layer's standardized for dialog and . In modern contexts, such as and beyond, session tokens and multiplexing further handle these functions within the , enhancing performance over multiple underlying connections.

With Other Network Models

In IBM's (SNA), functions analogous to the OSI session layer are primarily handled within the Data Flow Control (DFC) layer, which ensures data flow integrity through mechanisms like bracketing and chaining, and the Transmission Control layer, which manages explicit session establishment and termination for mainframe applications using Logical Units (LUs) and System Services Control Point (SSCP). This integration differs from the OSI model's distinct separation of session services, as SNA combines them with transport and network elements into composite layers to support hierarchical, host-centric operations. In Novell's IPX/SPX , session layer responsibilities are merged into the upper layers, with the Sequenced Packet Exchange (SPX) providing connection-oriented services at OSI layer 4, including reliable delivery and sequencing, while the NetWare Core Protocol (NCP) at layers 5 through 7 manages session establishment, maintenance, and termination for client-server interactions such as file and printer access via remote procedure calls. Unlike the OSI session layer's focus on dialog control and , NCP embeds these functions within application-specific services, optimizing for environments without a dedicated session protocol. Although the provided a standardized reference that influenced the evolution of proprietary architectures like and IPX/SPX during the 1980s, these stacks adapted session handling for vendor-specific needs, such as SNA's Advanced Program-to-Program Communication (APPC) under LU 6.2, which enables sessions across systems with explicit allocation and bracketing for distributed applications. This contrasts with the /IP model's more streamlined approach to session management, often embedding it within transport protocols like .

History and Modern Relevance

Development and Evolution

The concept of the session layer emerged in the late 1970s amid efforts to standardize network architectures for interconnecting diverse computer systems, drawing from pioneering work on the , which began operations in and demonstrated packet-switched networking principles. Parallel ISO initiatives, initiated through the Institute's 1977 proposal for a , sought to create a framework for open systems interconnection to enable communication across heterogeneous environments. Key influences included the French project (1971–1979), where engineer Hubert Zimmermann developed end-to-end protocols that emphasized datagram-based communication and informed the layered approach; Zimmermann later contributed directly to ISO's architecture design. The session layer was formalized as Layer 5 of the in ISO 7498, published in 1984, which established a seven-layer structure to promote vendor-independent by abstracting functions into modular components. This model built on a 1978 consensus at an ISO subcommittee meeting in , where Honeywell's seven-layer Distributed Systems Architecture—refined from mid-1970s and experiences—was adopted as the basis for OSI development. The session layer specifically addressed coordination between application processes, such as dialog management and , to support reliable interactions in multi-vendor s. A pivotal milestone was the definition of session services in ISO 8327, with drafts (DIS 8327) circulated in 1984 and the first full edition published in 1987, specifying the basic connection-oriented session protocol for establishing, managing, and terminating sessions between peer entities. This standard outlined services like activity management and to ensure robust communication. Updates came with ISO/IEC 8327-1 in 1996, a second edition that technically revised the 1987 version, incorporating amendments for enhanced efficiency and incorporating prior changes from 1992. Designed explicitly for in heterogeneous networks, the session layer facilitated seamless data exchange across diverse hardware and software by providing abstract interfaces independent of underlying mechanisms, aligning with OSI's goal of global standardization. However, its adoption remained limited during the and due to the rapid rise of the TCP/IP protocol suite, which was mandated for in 1983 and benefited from open implementations, U.S. government support, and faster deployment compared to OSI's bureaucratic development process. By the mid-1990s, TCP/IP's dominance in academic and commercial networks overshadowed , including session layer services, confining them largely to theoretical and niche applications.

Current Applications and Alternatives

In contemporary networking, the session layer's distinct functions have largely declined due to the dominance of the , which absorbed session management into the , rendering a separate session layer unnecessary for most implementations. Residual applications persist in legacy enterprise systems, such as those using (RPC) protocols like ONC RPC, where session establishment and dialog control facilitate remote execution across distributed environments. Modern protocols draw indirect influence from session layer concepts for persistent connections; for instance, WebSockets enable full-duplex, stateful communication over a single connection, managing ongoing sessions between web clients and servers to support real-time applications like chat or live updates. In and RESTful APIs, traditional session layers are bypassed through stateless alternatives like JSON Web Tokens (JWT), which encode user state and authentication in self-contained tokens passed with requests, eliminating server-side session storage while ensuring secure, scalable identity verification. Session state may also be offloaded to databases or caches for hybrid approaches in distributed systems. Similarly, leverages to integrate transport-layer connection management with session-like features, such as rapid handshakes and stream multiplexing, reducing latency for web sessions without a dedicated OSI session layer. The session layer's principles are virtualized in (SDN) and (NFV), where session management is abstracted into software controllers for dynamic orchestration, as seen in virtualized Session Border Controllers that handle multimedia session control in programmable networks. In (IoT) environments, session management remains relevant through protocols like , which supports persistent sessions for lightweight device communication, allowing reconnection and state retention across intermittent links.

References

  1. [1]
    What is the session layer OSI communications model? - TechTarget
    Apr 10, 2023 · The session layer is Layer 5 of the OSI communications model. It is the long-lived logical connection that persists between endpoints over time.
  2. [2]
    What Is the OSI Model? - 7 OSI Layers Explained - Amazon AWS
    ... ISO/IEC 7498-1:1994. The seven layers of the model are given next. Physical ... The session layer is responsible for network coordination between two separate ...
  3. [3]
    What is the OSI Model? | Cloudflare
    The OSI Model breaks down network communication into seven layers. These layers are useful for identifying network issues.
  4. [4]
    What Is the OSI Model? | IBM
    Layer 5: The session layer. The session layer is responsible for session management, the process of establishing, managing and terminating connections—called ...<|control11|><|separator|>
  5. [5]
    X.200 : Information technology - Open Systems Interconnection - Basic Reference Model: The basic model
    **Summary of OSI Model Session Layer (Layer 5) from ITU-T X.200:**
  6. [6]
    [PDF] Government open systems interconnection profile users' guide
    ... OSI protocols, and is designed to provide specific functionality within several adjacent layers of the OSI Reference Model. QUESTION 17: Does GOSIP provide ...
  7. [7]
    [PDF] IS0 8327 - iTeh Standards
    Aug 15, 1987 · The functions in the Session Layer are concerned with dialogue management, data flow synchronization, and data flow resyn- chronization. These ...
  8. [8]
    https://doi.org/10.1016/S0140-3664(97)00042-X
  9. [9]
    The OSI Model: Layer 5 - Session Layer - Firewall.cx
    It coordinates communication between systems and serves to organise their communication by offering three different modes: simplex, half-duplex and full-duplex.
  10. [10]
    RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1
    Below is a merged summary of HTTP/1.1 Communication Mode from RFC 2616, combining all the information from the provided segments into a concise yet comprehensive response. To maximize detail and clarity, I’ll use a table in CSV format for key aspects, followed by a narrative summary that integrates additional details and references. This ensures all information is retained while adhering to the constraint of no thinking tokens beyond the response itself.
  11. [11]
    Understanding OSI - Chapter 6 - Packetizer
    The session layer provides two orderly release mechanisms, both supported by the S-RELEASE request, indication, response, and confirm primitives. In the ...
  12. [12]
    [PDF] ISO/IEC - 8327-l - iTeh Standards
    Apr 3, 2021 · Overview of the session protocol ...............................................................................................................
  13. [13]
    [PDF] OSI Transport and Session Layer Protocols - Bitsavers.org
    Oct 11, 2018 · Token management, where tokens are used to imple- ment tum control. A token's owner can invoke certain services and functions, whereas the ...
  14. [14]
    X.225 - Connection-oriented Session protocol - ITU
    May 4, 2011 · X.225 : Information technology – Open Systems Interconnection – Connection-oriented Session protocol: Protocol specification. Recommendation X.Missing: date | Show results with:date
  15. [15]
    ISO/IEC 8327-1:1996 - Connection-oriented Session protocol
    Open Systems Interconnection — Connection-oriented Session protocol: Protocol specification ... Published (Edition 2, 1996).
  16. [16]
    https://pubs.opengroup.org/onlinepubs/009619199/apdxh.htm
  17. [17]
    Minimum OSI Functionality
    Session Kernel and Full Duplex functional units. The XTI-mOSI interface provides access to OSI ACSE and Presentation services. With mOSI, the optional ...
  18. [18]
    ISO 8327:1987 - Information processing systems
    Open Systems Interconnection — Basic connection oriented session protocol specification.
  19. [19]
    [PDF] ISO Reference Model for Open Systems Interconnection (OSI)
    Oct 11, 2018 · The first draft of the seven-layer OSI Reference Model was completed in 1978. ... Finalization Date. Working Draft. Next milestone to be.
  20. [20]
    [MS-CIFS]: NetBIOS-Based Transports - Microsoft Learn
    Jun 10, 2025 · The NetBIOS session service provides reliable, point-to-point transport. When using the NetBIOS session service, CIFS makes no higher-level ...
  21. [21]
    https://datatracker.ietf.org/doc/html/rfc5531
  22. [22]
    RFC 5531 - RPC: Remote Procedure Call Protocol Specification ...
    This document describes the Open Network Computing (ONC) Remote Procedure Call (RPC) version 2 protocol as it is currently deployed and accepted.
  23. [23]
    What is OSI Model | 7 Layers Explained - Imperva
    The OSI model describes seven layers that computer systems use to communicate over a network. Learn about it and how it compares to TCP/IP model.
  24. [24]
    [PDF] Introduction to AppleTalk - Apple Developer
    The AppleTalk protocols implemented at the session layer are ... The Zone Information Protocol (ZIP) maintains a zone information table in each internet.
  25. [25]
    draft-evans-v2-scp-00 - Session Control Protocol V 2.0
    SCP provides a simple mechanism for creating multiple lightweight connections over a single TCP connection. Several such lightweight connections can be active ...Missing: VoIP | Show results with:VoIP
  26. [26]
    RFC 3261 - SIP: Session Initiation Protocol - IETF Datatracker
    This document describes Session Initiation Protocol (SIP), an application-layer control (signaling) protocol for creating, modifying, and terminating sessions ...
  27. [27]
    Session Layer of OSI Model (Layer-5) - Networkwalks Academy
    Session Layer is the 5th layer in OSI model. It is mainly reponsible for sessions management through protocols like PPTP, L2TP and SIP.
  28. [28]
    RFC 793 - Transmission Control Protocol (TCP) - IETF
    The connection becomes "established" when sequence numbers have been synchronized in both directions. The clearing of a connection also involves the exchange of ...
  29. [29]
    Cisco Internetworking Basics
    In an architectural model, a layer does not define a single protocol--it defines a data communication function that may be performed by any number of protocols.
  30. [30]
    [PDF] Session Layer
    The ISO protocols provide both major and minor synchronization points. When resynchronizing, one can only go back as far as the previous major synchronization ...
  31. [31]
    RFC 959: File Transfer Protocol
    Summary of each segment:
  32. [32]
    RFC 6265 - HTTP State Management Mechanism - IETF Datatracker
    This document defines the HTTP Cookie and Set-Cookie header fields. These header fields can be used by HTTP servers to store state (called cookies) at HTTP ...
  33. [33]
    [PDF] OSI And SNA: A Perspective - Bitsavers.org
    Apr 10, 1981 · This paper will discuss similarities and differences between. Systems Network Architecture (SNA) of IBM and the ISO Reference ... (Session, ...
  34. [34]
    [PDF] NetWare Protocols - filibeto.org
    The Sequenced Packet Exchange (SPX) protocol is the most common NetWare transport protocol at. Layer 4 of the OSI model. SPX resides atop IPX in the NetWare ...
  35. [35]
    OSI: The Internet That Wasn't - IEEE Spectrum
    Jul 29, 2013 · May 1983: ISO publishes “ISO 7498: The Basic Reference Model for Open Systems Interconnection” as an international standard. 1985: U.S. National ...
  36. [36]
    THE ORIGINS OF OSI William Stallings
    When the ISO group met in Washington, DC in March of 1978, the Honeywell team presented their solution. A consensus was reached at that meeting that this ...<|separator|>
  37. [37]
    ISO 7498:1984 - Basic Reference Model
    Publication date. : 1984-10. Stage. : Withdrawal of International Standard [95.99]. Edition. : 1. Number of pages. : 40. Technical Committee : ISO/IEC JTC 1.
  38. [38]
    ISO/IEC 7498-1:1994(en), Information technology
    This reference model provides a common basis for the coordination of standards development for the purpose of systems interconnection.
  39. [39]
    https://www.iso.org/obp/ui/en/#!iso:std:20269:en
  40. [40]
    (PDF) The battle between standards: TCP/IP Vs OSI victory through ...
    Between the end of the 1970s and 1994 a fierce competition existed between two possible standards, TCP/IP and OSI, to solve the problem of interoperability ...
  41. [41]
    What is WebSocket? - HAProxy Technologies
    WebSocket is a stateful communication protocol that works at Layer 7 of the OSI model, enabling bi-directional message exchange between client and web ...
  42. [42]
    Complete Guide to JSON Web Token (JWT) and How It Works
    Apr 7, 2025 · Learn how JWT (JSON Web Token) works, its structure, and best practices for secure authentication and stateless session management.
  43. [43]
    RFC 9114 - HTTP/3 - IETF Datatracker
    This document defines HTTP/3: a mapping of HTTP semantics over the QUIC transport protocol, drawing heavily on the design of HTTP/2.
  44. [44]
    https://ieeexplore.ieee.org/document/6702554