Zachman Framework

The Zachman Framework, as it applies to enterprises, is a schema or structure for identifying and organizing the descriptive representations (models) that are important in the management of enterprises and to the development of the systems, both automated and manual, that comprise them. It was derived from analogous structures that are found in the older disciplines of Architecture/Construction and Engineering/Manufacturing that classify and organize the design artifacts created in the process of designing and producing complex physical products (e.g. buildings or airplanes). It uses a two dimensional classification model based on the six basic interrogatives (What, How, Where, Who, When, and Why) intersecting six distinct perspectives, which relate to stakeholder groups (Planner, Owner, Designer, Builder, Implementer and Worker). The intersecting cells of the Framework correspond to models which, if documented, povide a holistic view of the enterprise.

Originally conceived by John Zachman at IBM in the 1980s, the Framework is now a de facto world standard for expressing the basic elements of enterprise architecture. The Zachman Framework has been recognized by the U.S. Federal Government as having "... received worldwide acceptance as an integrated framework for managing change in enterprises and the systems that support them."

Characteristics

The Zachman Framework has been compared with the Periodic Table. In the same way that atoms in the the Periodic Table of Chemical Elements are identified as the building blocks of all matter, the cells in the Zachman Framework are identified as the building blocks of enterprises.

The columns of the framework, which have no order of importance, represent unique abstractions of the enterprise in order to reduce the complexity of any single model that is built. The cell models are described as "primitive models," in that in each there is only a single variable. "Composite models," which are comprised of two or more variables, are needed in the design of solutions to satisfy business requirements. John Zachman maintains that primitive models are necessary for reusability and for engineering commonality across an enterprise, and that only primitive models can be considered to be elements of architecture.

Each cell model in each column constrains the content of the cell below it. This ensures alignment between the intentions of enterprise owners, as represented by Row 2 of the framework, and with whatever is implemented to build the enterprise, as represented by Row 5 of the framework.

The granularity of detail in the Zachman Framework is a property of any individual cell regardless of any row. Depending on the requirement, planning or implementation, a cell model may have relatively little detail or an excrutiating level of detail.

The Zachman Schema

There are several versions of the diagram depicting the Zachman Framework for Enterprise Architecture. The diagram used in this article has been adapted from an official version that includes details about the cell models and which is made available by Zachman International.

Framework Rules

Adapted from: Sowa, J.F. & J.A. Zachman, 1992, and Inmon, W.H, J.A. Zachman, & J.G. Geiger, 1997

Rule 1: Do not add rows or columns to the Framework

The structure of the Framework as it has been designed identifies all possible primitive representations relevant to describing an enterprise. Adding rows or columns would introduce redundancies or discontinuities.

Rule 2: Each column has a simple generic model

The simple generic model for each column is the variable represented by the column as related to itself, e.g., the generic model for Column 1 is Thing - Relationship - Thing.

Rule 3: Each cell model specializes its column's generic model

The design of any cell model starts with its generic, columnar model and then adusted according to the semantic constraints of the row it is in.

Rule 4: No meta concept can be classified into more than one cell

Each cell is unique. There is no redundancy.

Rule 5: Do not create diagonal relationships between cells

People in the different perspectives - Owner, Designer, Builder - often use the same terms to express different concepts. Creating diagonal relationships leads to semantic discord and misinterpretation.

Rule 6: Do not change the names of the rows and columns

For the same reason as for not adding rows and columns, changing the names may change the fundamental logical structure of the Framework.

Rule 7: The logic is generic, recursive

The Framework is generic in that it can be used to classify the descriptive representations of any physical object as well as conceptual objects such as enterprises. It is also recursive in that it can be used to analyze the architectural composition of itself.

The Zachman Framework and Enterprise Architecture

The Zachman Framework does not prescribe how any cell model is to be be created, including any notation or level of detail. This is left to organizations to determine, based on the methodologies they have adopted. The Zachman Framework is not an enterprise architecture methodology, nor is it an enterprise architecture. It is a classification schema for the descriptive representations (primitive models) that, if created, would comprise an enterprise architecture.

Organizations that adopt the Zachman Framework approach to enterprise architecture for engineering their enterprises require a methodology for carrying out the following functions:

a. Build primitive models

b. Store primitive models

c. Manage (enforce) primitive models

d. Change primitive models

e. Assemble composite models from primitive models (for implementations)