====== Interface ======

[[public:99_annexes:annex-b-terms-and-definitions:start|Go up to Terms and Definitions]]

 entsch pleasantly===== Discussion =====

An Interface is a defined boundary through which two or more participants interact or exchange [[public:99_annexes:annex-b-terms-and-definitions:d:data|Data]], commands, events, services, or other [[public:99_annexes:annex-b-terms-and-definitions:r:resource|Resources]].

An Interface identifies what a participant provides, requires, accepts, or produces at the boundary without necessarily exposing how the participant implements its internal behavior. An Interface may exist between Systems, components, services, organizations, human Actors, or governed [[public:99_annexes:annex-b-terms-and-definitions:d:domain|Domains]].

An Interface specification may define:

  * Provided and required capabilities
  * Operations, messages, events, or exchanged Data
  * Inputs, outputs, and permitted interaction sequences
  * Information-exchange [[public:99_annexes:annex-b-terms-and-definitions:s:structure|Structures]]
  * Associated [[public:99_annexes:annex-b-terms-and-definitions:s:semantic|semantic]] meaning
  * Protocols and interaction patterns
  * Preconditions, postconditions, and [[public:99_annexes:annex-b-terms-and-definitions:c:constraint|Constraints]]
  * Identity, authentication, authorization, and trust requirements
  * Error handling, failure behavior, and recovery expectations
  * Performance and Quality of Service characteristics
  * Version and compatibility information
  * Applicable [[public:99_annexes:annex-b-terms-and-definitions:p:policy|Policies]] and governing [[public:99_annexes:annex-b-terms-and-definitions:a:authority|Authorities]]

An Interface separates an externally visible interaction from its internal realization. Different implementations can conform to the same Interface when they provide the specified behavior and satisfy the applicable Constraints.

An [[public:99_annexes:annex-b-terms-and-definitions:a:api|Application Programming Interface (API)]] is an Interface type intended for interaction with software. Not every Interface is an API. Interfaces may also describe message exchanges, network interactions, organizational exchanges, human interactions, physical connections, or Governance handoffs.

Within a [[public:99_annexes:annex-b-terms-and-definitions:f:federation|Federation]], Interfaces establish explicit interaction boundaries among independently governed participants. Defined Interfaces support [[public:99_annexes:annex-b-terms-and-definitions:i:interoperability|Interoperability]] without requiring each participant to expose or surrender control over its internal implementation.

===== Definition =====

//a defined boundary through which participants interact or exchange Data, commands, events, services, or Resources//

===== Source =====

Generalized from ISO/IEC/IEEE 42010 architectural-description concepts and OMG interface-specification practices and specialized for SIP-RA use across independently governed Systems and Domains.

===== Note =====

An Interface is not merely a connection. A connection provides a path between participants. An Interface defines the characteristics and conditions of the interaction conducted through that path.

An Interface specification does not, by itself, guarantee Interoperability. Participating implementations must conform to compatible structural, semantic, protocol, behavioral, security, and Governance requirements.

===== Example =====

A logistics information-exchange Interface defines the readiness reports that a military service provides to coalition partners. The Interface specifies the message Structure, semantic meaning, exchange protocol, authorization rules, version, error handling, and required Evidence without prescribing the internal implementation of each participant’s logistics System.

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