CHAPTER 1: WHAT IS ENTERPRISE ARCHITECTURE? – Enterprise Architecture: A Pocket Guide


Some definitions

What is enterprise architecture, and why does it matter to business and to the governance1 of business and IT?

The Practical Guide for the US Federal Enterprise Architecture Framework defines enterprise as:

‘…an organisation or cross-functional entity supporting a defined business scope or mission. [It] includes interdependent resources – people, organisations and technology – who must coordinate their functions and share information in support of a common mission or set of related missions.’2

Note that, as the same document also emphasises:

‘…in many cases, the enterprise may transcend established organisational boundaries – e.g. trade, grant management, financial management, logistics.’

A shared enterprise that extends beyond the organisation – as in a supply-chain or an industry consortium – may require more complex forms of governance, based on negotiation between partners rather than straightforward executive decisions.

The Practical Guide defines architecture as:

1 See Chapter 3 for the specific meanings of ‘governance’ as used here.

2 See

‘…the structure of components, their interrelationships, and the principles and guidelines governing their evolution and design.’

In effect, an ‘architecture’ in this context defines the content for a ‘knowledge base’ about structure, components, interrelationships and principles that are relevant to the needs of the enterprise.

Note that the Practical Guide definition above does not restrict ‘architecture’ to a predefined scope, such as software or IT. Despite the common assertion – such as in the TOGAF™3 specification – that enterprise architecture is a subset of IT governance, its scope could, and for consistency generally should, extend to the entire enterprise.4

Combining the definitions above, enterprise architecture is thus a discipline through which an enterprise can identify, develop and manage its knowledge of its purpose, its structure and itself. Some of that knowledge will be about IT, but it will also need to include many other concerns:

• business architecture

• organisational structure

• performance management

• business continuity/resilience planning

• process architecture

• security architecture

• data architecture

• applications architecture

• technology – infrastructure architecture.

3 TOGAF™ Version 9, Van Haren, 2009.

4 Tom Graves, Real Enterprise Architecture, Tetradian, 2008.

As a discipline, enterprise architecture provides a means to link together all of these differing ‘architectures’ and structural concerns.

Why enterprise architecture matters

The business purpose of the enterprise architecture body of knowledge is to provide decision support for direction and change at any level of the enterprise. Such decisions might include:

• executive – what the enterprise is and does, where it’s going, the choices in that journey

• programme and portfolio management – preferred technologies or process models for new developments

• operations planning – when to decommission an outdated legacy system

• resilience planning – alternative systems expected to be online by a specific date.

For example, the business questions enterprise architecture could be used to answer include:

• ‘What structures would we need to support this strategy?’

• ‘What constraints will our existing structures place on our strategic choices?’

• ‘What opportunities would be available to us with these innovations in our structures?’

• ‘How quickly could we align the systems of this newly-acquired company with our own?’

Within the upper levels of the organisation, decision support from enterprise architecture will simplify the ‘conversation’ between strategy – which sets enterprise direction – and an enterprise-wide programme management office (or equivalent) which implements the changes in capabilities and facilities required for each new strategy.

Enterprise architecture will also assist in managing changes imposed on the organisation from outside, by the market, by regulations, or – at an operations level – by system failures, environmental incidents or customer complaints. A more mature enterprise architecture will be able to map interdependencies across almost every aspect of the enterprise. This would aid resilience planning, for example, by identifying the probable impact that a server failure would have on key business-performance metrics; or compliance management, by indicating the manual and automated parts of processes that would be affected by new legislation.

A well-defined and well-maintained enterprise architecture is also proven to be a key factor in an organisation’s agility, effectiveness and ability to respond to risk, opportunity and change.5

5 Jeanne Ross, Peter Weill and David Robertson, Enterprise Architecture as Strategy, Harvard Business School Press, 2006.