Why is PERA Needed ?


An Enterprise Architecture is a "model" or a "framework" which can be used to represent an enterprise. This framework can be used to assist with planning and analysis of the enterprise, to select hardware and software products for use at different phases of the enterprise, to design organizational "reporting structures", and to study flow of materials and information throughout the enterprise.

Without an Enterprise Architectural model, executives, managers, and technologists in an enterprise are by default, making decisions based on their personal models of the enterprise. Typically, these are limited to a small part of the enterprise, and only one or two phases. Furthermore, even these limited models are typically not effectively shared with the rest of the organization.

PERA is a GERAM, a Generalized Enterprise Reference Architectural Model. As, such, it extends more limited Type 1 and Type 3 "specific" Enterprise Models, to a generalized model which can be applied to all industries and all enterprise phases. Without such an overall model of the enterprise, interfaces between software tools, databases, workprocesses, etc., used in different parts and phases of the enterprise are difficult or impossible to integrate. These existing tools and databases are currently often defined within limited Type 1 and Type 3 Architectures.

A GERAM also makes It possible to define these tools, databases, etc., in terms of a reference system which can be applied across industries, and phases (and across software manufacturers). Ultimately, this will allow common features to be identified and improved, and only the components which require unique implementation needl be custom programmed. Similarly, interfaces between common and unique elements can be defined and implemented in standard ways. SP95 is an early attempt to define one of these interfaces (between plant or shop floor databases and frontoffice MIS databases) in an vendor independant way.

At this time, it is generally ageed by world enterprise integration experts that PERA is the best candidate for an overall GERAM, and work is progressing at integration of the best features of other models into the PERA framework.
Since no adequate tools for this purpose were previously available, we have proposed a Control and Information Architecture Diagram (CIAD) which serves the same purpose as the PFD or MFD for the Production Facility component of the enterprise and is also developed during the Conceptual Engineering Phase of the Enterprise. PHYS_ARC_small.gif - 5615 Bytes

As the Enterprise design proceeds, the information on the CAID is develped into a Control and Information Network Diagram (CIND). This parallels the development of the P&ID from the PFD, or the M&ID from the MFD. This CIND document is at a "higher level" than the P&ID in the Control and Information Architecture, and thus "completes" the low level Control and Information System structure presented on the P&ID. The CIND is also developed during the "Preliminary Engineering" phase at the same time that the P&ID is being developed..

The rules for content and presentation of information on the CIAD and CIND are explained in more detail under "What is a Control and Information Architecture".

Taken together, the above defines the complete Enterprise Architecture Although formats of each of the three architecture components (Facilities, People and Information Systems) vary, the intent is the same: to provide a coherent and coordinated representation of the enterprise during that phase. It is also true for all three architecture components, that additional detail is added in each successive phase by building on the Architecture defined in the previous phase.

A key message of PERA is that the "horizontal" interfaces between enterprise components are critical, as well as the "vertical" interfaces between phases. It is critical that Management understand these interfaces in their organization, and take appropriate measures to minimize their impact.

Static, steady state, and dynamic analysis of the Production Facility, Human Organization, and the Control and Information Systems is often carried out as part of the development of that enterprise. However, the PERA model indicates that the interfaces between these three components of the Enterprise (Facilities, People and Information Systems) must also be modelled. In fact, in many cases, flow across these interfaces are the controlling factor in the dynamic behavior of the Enterprise.

Until the multitude of providers of software tools adopts a common Enterprise Model (such as PERA), information integration between their tools will remain difficult if not impossible

Many tools are available for modelling each of the three enterprise components individually, and these are discussed for each phase of each industry elsewhere in this web site. However, no tools are available which can effectively model all three, let alone all of the interfaces between them. This is the great challenge facing the next generation of enterprise architects, and it will require a fundamentally different approach to modelling, and software interfacing. Perhaps the new generation of OOP (Object Oriented Programming) and database interface tools can help, however, until the providers of such tools adopt a common Enterprise Model (such as PERA), no such interface between their industry-specific and phase-specific modelling tools will be possible.


by Gary Rathwell reserved
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