Is There More Than One Type of Enterprise Reference Architecture ?

Yes, The Task Force has defined three types of Enterprise Reference Architectures (also called Frameworks).

All three can provide "models" or "go-bys" to use when designing or revamping an enterprise, however, only Type 2 (GERAM) provides a generalized model which can be applied to all industries during all phases.

Type 1 Enterprise Architectures & Models - Specific Implementations

Type 1 Models are specific implementations of individual enterprises at a point in time.

That is, they represent a specific case of a enterprise system including hardware, software, work processes and people, at one point in the life cycle (e.g. at plant startup). There are, of course, many examples of Type 1 "Architectures" which have been published, often with detailed descriptions of the application and particular hardware and software used.

A number of generalized Type 1 enterprise models describing hardware and/or software implementations for particular industries or applications are presented under Type 1 Physical and Logical Architectural Models.

Type 2 - GERAMs (Generic Enterprise Reference Architectures & Models)

GERAMs, as defined by the Task Force on Architectures for Enterprise Integration, are models of the life cycle of an enterprise or system from its initiation to its final dissolution. That is, they are Complete Life Cycle Reference Framework Models which may be used to guide the Development of an Enterprise Integration or Business Reengineering Project or Program. These are also called Type 2 Architectures by the Task Force.

The following is a list of Candidate GERAMs:

The PERA enterprise reference model has been selected by Fluor Daniel, the world's largest EPC company, to design  automated facilities ranging from multi-billion dollar petro-chemical plants, to 911 Emergency Response Centers.

Type 3 - PRAMs (Partial Reference Architectures & Models)

Type 3 Methodologies (Architectures) are applicable only for specific industries and/or phases of the Enterprise life cycle. Examples might include methodologies to design accounting systems for banks, or automation systems for chemical plants. Also, some methodologies may only be applicable during one phase, such as the programming phase of a computer system, or the detail engineering design of a plant. This specialization of methodologies has resulted from the historical focus of companies to serve particular industries (e.g. Pharmaceuticals), or enterprise phases (e.g. plant construction).

Because they are incomplete, they cannot be called Type 2 GERAMs, and yet, since they cover multiple phases of the life cycle, they are not Type 1 (architectures at a point in time). We therefore suggest a third category of "Type 3" Architectures which describe these "Partial" Architecture Methodologies.

by Gary Rathwell reserved
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