What should an interface control document contain

An interface, from the perspective of system development, can be identified as any point where a system and something, or someone, meet.

This interface point may include other systems, internal hardware, circuitry, external peripherals, networks, system users, etc. For example, common interfaces for computer peripherals may include USB, serial, parallel ports, etc; common interfaces for system users may include monitors, keyboards, mice, etc.

Interfaces are documented using interface control documents ICD that describe the system's interfaces as well as any rules for communicating with them. ICDs help ensure compatibility between system segments and components and are often considered key elements of effective system design and development.

The purpose of the ICD is to clearly communicate all possible inputs and outputs from a system for all potential actions whether they are internal to the system or transparent to system users. An ICD may describe the system interfaces to the lowest physical elements circuits, voltage, watts, etc to the user interface or any subset thereof.

The level of detail included in any ICD is dependant upon the requirements of the stakeholders to successfully deliver on project requirements. Definition Email this page to a friend. For example in the case of a communications interface the following technical details are provided: Type: the type of interface; for example, task to task, external, user , serial CCITT RS - , parallel Protocol: a description of the communications protocol.

Protocol descriptions may include: Message format and description including user error messages, user information messages and interprocess messages Message component names Message initiation The processing of message interruptions. Fragmentation and reassembly of messages Error detection, control and recovery procedures Synchronisation, including connection establishment, maintenance, termination and timing and sequencing Flow control, including sequence numbering, window size and buffer allocation Data transfer rate Transmission services including priority and grade Security including encryption, user authentication and auditing Error codes.

A user interface is typically described as follows: User inputs Screen formats Interaction dialogue scripts Use cases References to error and information messages. A hardware interface is described with circuit diagrams.

This section should illustrate the interface and the data exchanged between the interfaces. Further information on the functionality and architecture of the participating systems is given the subsequent sections. In particular, each system should be briefly summarized with special emphasis on the functionality related to the interface. The hardware and software components of each system are also identified. Describe the functionality and architecture of the interfacing system as it relates to the proposed interface.

Briefly summarize the system, placing special emphasis on functionality, including identification of key hardware and software components, as they relate to the interface. If more than one external system is to be part of the interface being defined, then include additional sections at this level for each additional external system.

Briefly describe what operations are performed on each system involved in the interface and how the end users will interact with the interface being defined. If the end user does not interact directly with the interface being defined, describe the events that trigger the movement of information using the interface being defined.

Briefly describe how data will be moved among component systems of the interface being defined. Include descriptions and diagrams of how connectivity among the systems will be implemented and of the type of messaging or packaging of data that will be used to transfer data among the systems. If more than one interface between these two system is defined by this ICD, each should be identified in this section. A separate subsection 2. This ICD template will be primarily used for specification of interfaces that move information between two systems.

Where an interface contains physical requirements that are imposed upon one or both of the interfacing systems, these physical requirements should be described in Section 2. If an interface has no physical requirements, then so state. Briefly describe the types of transactions that will be utilized to move data among the component systems of the interface being defined. If multiple types of transactions will be utilized for different portions of the interface, a separate section may be included for each interface.

If the interface defined has security and integrity requirements, briefly describe how access security will be implemented and how data transmission security will be implemented for the interface being defined. Include a description of the transmission medium to be used and whether it is a public or a secure line. Include a brief description of how data will be protected during transmission and how data integrity will be guaranteed. Include a description of how the tow systems can be certain that they are communicating with each other and not with another system masquerading as one of them.

Describe how an individual on one system can be audited and held accountable for resulting actions on the other component of the interface. Normally, this section should be an overview of how security and integrity will be implemented, with Section 3. An interface that is completely self-contained, such as movement of data between systems resident in the same computer room, may not have any security requirements.

In this case, it should be so stated with an explanation of why the interface has no security and integrity requirements. This section specifies the requirements for one or more interfaces between two systems. This includes explicit definitions of the content and format of every message or file that may pass between the two systems and the conditions under which each message or file is to be sent. If an interface between the two systems is t be implemented incrementally, identify the implementation phase in which each message will be available The structure in paragraph 3.

The template contained in Section 3. The specific interface definition should include only subsections relevant to the interface being defined and considerable liberty may be taken in the organization of Section 3. Where types of information not specified in Section 3. Other readily available documents such as data dictionaries, standards for communication protocols, and standards for user interfaces may reference in place of stating the information here.

It may useful to include copies of such documents as attachments to the ICD. Where possible, the use of tables and figures is encouraged to enhance the understandability of the interface definition.