A reference model in systems, enterprise, and software engineering is an abstract framework or domain-specific ontology consisting of an interlinked set of clearly defined concepts produced by an expert or body of experts in order to encourage clear communication. A reference model can represent the component parts of any consistent idea, from business functions to system components, as long as it represents a complete set. This frame of reference can then be used to communicate ideas clearly among members of the same community.
Reference models are often illustrated as a set of concepts with some indication of the relationships between the concepts.
According to OASIS (Organization for the Advancement of Structured Information Standards) a reference model is "an abstract framework for understanding significant relationships among the entities of some environment, and for the development of consistent standards or specifications supporting that environment. A reference model is based on a small number of unifying concepts and may be used as a basis for education and explaining standards to a non-specialist. A reference model is not directly tied to any standards, technologies or other concrete implementation details, but it does seek to provide a common semantics that can be used unambiguously across and between different implementations."
There are a number of concepts rolled up into that of a 'reference model.' Each of these concepts is important:
Abstract: a reference model is abstract. It provides information about environments of a certain kind. A reference model describes the type or kind of entities that may occur in such an environment, not the particular entities that actually do occur in a specific environment. For example, when describing the architecture of a particular house (which is a specific environment of a certain kind), an actual exterior wall may have dimensions and materials, but the concept of a wall (type of entity) is part of the reference model. One must understand the concept of a wall in order to build a house that has walls.
Entities and relationships: A reference model describes both types of entities (things that exist) and their relationships (how they connect, interact with one another, and exhibit joint properties). A list of entity types, by itself, doesn't provide enough information to serve as a reference model.
Within an environment: A reference model does not attempt to describe "all things." A reference model is used to clarify "things within an environment" or a problem space. To be useful, a reference model should include a clear description of the problem that it solves, and the concerns of the stakeholders who need to see the problem get solved.
Technology agnostic: A reference model's usefulness is limited if it makes assumptions about the technology or platforms in place in a particular computing environment. A reference model typically is intended to promote understanding a class of problems, not specific solutions for those problems. As such, it must aid the process of imagining and evaluating a variety of potential solutions in order to assist the practitioner. Note: That does not preclude the development of a reference model that describes a set of software applications, because the problem space may be "how to manage a set of software applications."
Instances of reference models include, among others:
Agent Systems Reference Model,
Core Architecture Data Model reference model of DoDAF
Federal Enterprise Architecture Framework reference model of the FEA
HP Information Security Service Management (ISSM) - Reference Model (RM)
IBM Information Framework, a reference model for financial services.
NIST Enterprise Architecture Model reference models from several Federal Enterprise Architectures
OGC Reference Model (Open Geospatial Consortium),
OpenReference, a open reference model for business performance, processes and practices,
Open Systems Interconnection Basic Reference Model,
Purdue Enterprise Reference Architecture
Real-time Control System for real-time control problem domains
Reference Model of Open Distributed Processing,
TAFIM was the 1990 reference model of the earlier version of the DoDAF, and
Von Neumann architecture as a reference model for sequential computing,
Digital Library Reference Model;
ENVRI (Environmental Research Infrastructures) Reference Model;
