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Educational Systems Ltd. The Open Group® and TOGAF® are registered trademarks of the Open Group in the United States and other countries

Of all the material in TOGAF®, the chapter that causes most problems, especially for students who are new to enterprise architecture, is Chapter 34. Content Metamodel.

In this multi-part Guideline, we explain the TOGAF metamodel in a simple way to help you prepare for the TOGAF exam, and we give you plenty of useful advice so that you can supplement the TOGAF material with a good knowledge of enterprise architecture metamodel practice.

What is a metamodel?

Let’s start by explaining the concept of a metamodel. TOGAF provides a very basic definition in Section 3.45 Metamodel:

A model that describes how and with what the architecture will be

described in a structured way.

What does this mean? The best way to explain is to break the term down into two parts – “model” and “meta”.

A model is a representation of something; for example, we might make a model of a building to show what it looks like. We could also make a model of an idea or something that is conceptual, such as a business model or an operational model. So, a model is a smaller scale or conceptual description of something. A model might also be used as something that can be copied, followed, or imitated; for example, an innovative product might become a model or prototype for further products.

Now let’s say that you’ve already got a business model, and the thing that you now want to “model” or represent is that business model. If you create another model which describes the business model, that would be a meta-model. Meta is used as a prefix to indicate a concept which is an abstraction of another concept.

It might help to visualise this in layers. At one level, there is the actual enterprise. Go up a level and we might have a model “of the enterprise”. Go up another level and we have a model “of the model of the enterprise”. In this example, we have the enterprise, a model, and a meta-model.

Bringing this back to TOGAF and enterprise architecture, there is an enterprise, which has an enterprise architecture. The enterprise architecture can be represented in a model, which in turn can be modelled as an EA metamodel.

TOGAF Series #79 | ATL002:79

Guideline – Using the TOGAF Metamodel PART 1 What is a metamodel and why is it useful?by Roger Evernden

© Copyright 2016 Good e-Learning. All rights reserved. No part of this publication may be reproduced, resold, stored in a retrieval system, or distributed in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the copyright owner. Such requests for permission or any other comments relating to the material contained in this document may be submitted to: marketing@goodelearning.com. Good e-Learning is a trading name used by

Educational Systems Ltd. The Open Group® and TOGAF® are registered trademarks of the Open Group in the United States and other countries

Why is a metamodel necessary or useful?

We can make this a bit simpler – the metamodel describes the types of component that make up the enterprise architecture. Going back to our meta layers – there are the actual components that make up the enterprise architecture (all the applications, processes, and services), and then at a higher meta level there are the types of component (application, process, and service)..

This is both necessary and useful. As architects, we need to describe the components and structure of the architecture. The metamodel describes the types of component that exist in our enterprise architecture. The metamodel gives us a framework that helps us to organize information about architecture components and how they are configured.

Identifying and specifying architectural components or building blocks is one of the core roles for an architect. Another core role is specifying how the components should be configured. The metamodel is an essential tool for doing both tasks effectively.

But there’s more…. The TOGAF documentation states:

“The TOGAF Architecture Development Method (ADM) provides a process lifecycle to create and

manage architectures within an enterprise. At each phase within the ADM, a discussion

of inputs, outputs, and steps describes many architectural work products or artifacts,

such as process and application. The content metamodel provided here defines a formal

structure for these terms to ensure consistency within the ADM and also to provide guidance

for organizations that wish to implement their architecture within an architecture tool.”

(Section 34.1 Overview)

So, the metamodel is also useful for:

• Producing consistent and precise descriptions of the architecture, in the form of work products or artifacts.

• Guiding the selection or creation of EA tools or repositories, by explicitly describing the information that needs to be stored and how that information might be used.

There is one other important use for the metamodel that isn’t mentioned in TOGAF. EA needs to be able to “view” the architecture from the many different viewpoints of its diverse stakeholders, which means that there might be alternative names for components, that the boundary of a component is not necessarily the same for all stakeholders, and that there may be components that are meaningful to some stakeholders and not to others. The metamodel is an excellent tool for documenting these divergent perspectives and allowing the architect to identify synergies.

Key points:

Don’t overlook the importance of a good EA metamodel!

It is used for:• Defining types of EA components and their

relationships.• Structuring and organizing information about

the enterprise architecture• Producing consistent and useful artifacts• Selecting appropriate EA tools and repositories• Managing stakeholder views and viewpoints