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Interface Management

DAU GLOSSARY DEFINITION

Alternate Definition

Interface management addresses interfaces between products "...as being managed by mutually agreeing to defined common product attributes, making them part of product configuration baselines for each product, and applying a product to maintain interface integrity."

Alternate Definition Source
General Information

Background

SAE EIA-649B has been adopted by the DoD as the Industry standard intended for use when establishing, performing, or evaluating Configuration Management (CM) processes. The standard consolidates content and terminology contained in the SAE Executive Group for Automotive Standards (GEIA) -HB-649, Configuration Management Handbook and Military Handbook (MIL-HDBK)-61B Configuration Management Guidance, and provides the principles evoked within SAE EIA-649-1 Configuration Management Requirements for Defense Contracts.

All content from the SAE EIA and GEIA listed above are copyrighted © and are reprinted with permission. All rights are reserved.

Interface Management as Part of CM

Per SAE EIA-649B, CM is "...a technical and management process applying appropriate resources, processes, and tools to establish and maintain consistency betwen the product requirements, the product, and associated product configuration information. CM facilitates:

  • Orderly identification of product attributes
  • Provides control of product information
  • Manages product changes that improve capabilities, correct deficiencies, improve performance, enhance reliability and maintainability, facilitate interface control, or extend product life, and
  • Manages departured from product requirements.

(Note:  bold text added for emphasis)

As such, a product's interfaces, including systems, equipment, software, and data are identified and documented in product configuration information that their integrity may be maintained through a disciplined configuration management change process that addresses the construct of "Form, Fit, Function, Interface (F3I)."

Interface Type, Relationship and Documentation

A product's interface attributes are the functional and physical characteristics that exist at the common boundary with co-functioning or physically attaching products. Analyzing interfaces categorizes their context and environment so that the appropriate definition and management of each interface can be determined. Interface analysis involves identification of the interface type and relationship. The first part of the analysis is determining if the interface is at the system, configuration item (CI), assembly, or part level.

The figure below identifies the interfaces that may exist either between systems or products or within a system or product, along with the associated interface documentation.

Configuration

Baseline

Type

of Interface

Interface Documentation
Functional Top Level system Interface requirement
  • System Specification
  • Interface Control Document (ICD)
Allocated Subsystem and CI Interface requirement
  • Subsystem and CI Specifications
  • Interface Control Documents (ICD)
  • Software Requirements Documents
  • Software Interface Requirements Documents
Design Release (developmental

Incremental/Current Software Baselines
Product, CI, Computer Software Configuration Item (CSCI), component part, and software unit detailed design interfaces (as the design evolves).

Functional and Allocated interface requirements implemented in design:

  • Assembly, Installation Drawings
  • Design Drawings/Part Models with interface characteristics noted
  • Software Design Documents
  • Software Interface Design Documents
  • Version Description Documents
Product Verified interfaces at all system/product/CI/CSCI/component part levels All Product Definition Information above with interface definition

Figure 1 Interface Documentation Related to Configuration Baselines

Interfaces include external interfaces between systems which make up Systems of Systems (SoS), internal interfaces between CIs that comprise a system or product, and internal interfaces of components within a CI.

Interfacing items may require parallel design/development, or may be existing items. Physical items may be electrical, electronic, mechanical, hydraulic, pneumatic or mechanical. Performance requirements may be requirements for operating range, frequency, transmission rate, or capacity. Software/data interfaces may be interoperability, language, development/test standards and facilities.

Contractual Relationships Between Parties

Contractual relationships provide vehicles for the definition and control of interfaces. The interface definition needs to be included in the contractual agreement as part of a defined catalog item or use of a control drawing and/or specification. If no relationship exists, an interface agreement may be necessary to provide the obligations between the parties.

The interface agreement defines the interface process, protects Intellectual Property (IP) and identifies procedures for defining and maintaining the interface and coordination proposed changes. It may establish an Interface Control Working Group (ICWG) or Integrated Product Team (IPT) to address interface issues. These processes extend to elements within a company as well as subcontractor, vendors and suppliers.

The interface definition includes performance, functional, and physical attributes. It is detailed in an interface control document/drawing, or a version controlled database, and is included in the functional and allocated baselines for interfacing products.

When two or more different customers or users of interfacing interoperable items are involved, an interface agreement or memorandum of agreement may be necessary to define the authority and responsibility for coordinating and approving changes affecting the interface and how issues may be resolved by an ICWG or IPT.

Systems Engineering (SE) Interface Management Processes

Interface management is classified as an SE technical management process. As such, the interface management process provides a framework to identify, define, manage and ensure compliance with internal and external system interfaces. The interface management process helps ensure that developers capture all internal and external interface requirements and requirements changes in accordance with the program’s CM Plan (CMP). Materiel developers also should communicate interface information to their counterparts responsible for affected systems and system elements, and should plan for coherent testing to verify expected performance and, ultimately, operational performance.

Per DoD Instruction (DoDI) 5000.88, Engineering of Defense Systems, an SE Plan (SEP) is required required for Major Defense Acquisition Programs (MDAP) and acquisition category (ACAT) II and III programs, and are a recommended best practice for all other defense system development. The SE Plan (SEP) Outline provides useful information how to address interface management within a SEP and states, "The SEP will address system integration with existing and approved architectures and capabilities. Program managers [PM] will identify and manage risk of external dependencies which are outside their span of control in order to ensure timely design, development, deployment, and sustainment of the system. Program managers will document interface requirements and interface products to track interdependent program touch points."

The use of standard interface specifications enables a Modular and Open Systems Approach (MOSA) because it facilitates innovation and competition in future technology insertion and refresh efforts for the system. When necessary to use a non-standard interface specification, acquiring the rights to the design as part of the program's IP Strategy may be an enabling option.

Explicit management of the definition, development, implementation and test of internal and external interfaces, including any associated dependencies, helps ensure that systems operate as designed and meet stakeholder expectations throughout the life cycle. The DoD Architecture Framework (DoDAF) provides guidance on how to generate operational and smystem views that describe interface relationships in a manner common across the DoD user community.

Interface Management as Part of Program Management

Interface management should consider programmatic issues such as roles and responsibilities, funding and scheduling in addition to the technical aspects of SE and integration.

The PM and Systems Engineer should ensure that the developer documents all system interface requirements as part of the Requirements Management Process. They need to ensrue the developer places them under appropriate levels of CM control and makes them available to the appropriate stakeholders. These documented interface requirements serve critical functions at all levels of the system throughout the life cycle, including:

  • Developing functional and physical architectures
  • Facilitating competitive bids
  • Enabling integration of systems and lower-level system elements
  • Supporting system maintenance, future enhancements, and upgrades
  • Providing input data for continuous risk management efforts

Systems Engineer Responsibilities

The Systems Engineer responsible for interface management has numerous key tasks throughout the life cycle, including:

  • Defining and establishing interface specifications
  • Assessing compliance of interfaces among CIs composing systems or SoSs
  • Monitoring the viability and integrity of interfaces within a system.
  • Establishing an interface management plan in conjunction with the CMP to assess existing and emerging interface standards and profiles, to update interfaces and to abandon obsolete architectures
  • Participation in a ICWG and or IPT

Applicable Data Item Descriptions (DID)

DIDs to support the interface management industry standards were approved in April 2015 and are accesseble via the uploaded into the ASSIST database. The DIDs are identified and hyperlinked within the references section of this article. Additionally, applicable DoD forms have been approved and posted on the Defense Technical Information Command (DTIC) DoD Forms Management Program website.