Report: Interface Requirements Specification
This report describes the requirements imposed on the system to support particular interconnections external to the system. Acceptance of the system by the customer is conditional on support for interfaces and connections as specified here. The title of this report, and its companion the Interface Design Specification , is chosen to make it familiar to those used to working with the Interface Requirements Specification (IRS) and Interface Design Description (IDD) that were required by software development standards such as Mil-Std-498. Its use here is extended beyond software interconnections to include, for example, mechanical, electrical, thermal, and human interconnections. Thus, a collection of these reports could cover the needs of the Interface Control Document (ICD), a well-known artifact to those in the systems engineering domain. Note that the usage of the term "interface" here is not strictly in accordance with UML. Described in these reports are interconnects , which have at least two interfaces, one to the system and one to the actor, and some type of connection between the two. From the perspective of the system, it offers, provides , or supports an interface (realizes it in UML terminology) and requires an interface to be realized by the actor (at the other end of the connection). In this way, the interconnect forms a contract between system and actor. This report is concerned with what is required, and so identifies actors, the entities that flow between the actors and the system (and any constraining protocols), and any requirements or constraints on the connection.
Relationships
Main Description

Identification and overview

Briefly identify the system and the interfacing entities which this report describes.

Interface requirements

Diagram

Include the initial Context Diagram (show only what is required -for example, UML interfaces usually come later, as part of design). Label each interconnect (usually one for each actor-system pair).

Interconnects

For each labeled interconnect, include a paragraph which briefly describes (as appropriate):

  • The interfacing entities (usually only the actor, because the other end is the system in each case).
  • The type of the interconnect (for example, data transfer, mechanical linkage, mass or energy transfer).
  • Logical and physical constraints on the connection, for example the medium, bandwidth, reliability, latency, attenuation, security or privacy considerations (such as encryption), dimensions, loads, tolerances, voltages, and so on. Do not specify these as requirements if the specification of logical and physical characteristics can be deferred until design or implementation.
  • Required protocols for actor-system exchange or communication to occur reliably, for example, signal timing, data packetizing, synchronization, startup, shutdown, error handing and recovery, and so on.
  • The items that flow between the actor and the system, describing, for example:
    • Item name (or identifier) and description (and whether the item is input to the system, output from the system, or both)
    • Nature of item and its characteristics - for example, if data, then include the data type; units of measurement; range of values; accuracy; precision; item size; item transfer rate; latency. Also, describe any composite items (arrays, records, files) unless this is implicit in the type.