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May 8th, 2006: Definition of Architecture

For a large number of years there has been a discussion on a definition of the term architecture. My definition is simple:

Architecture is a shared view on a reality

Where:

• Reality:

  in its simplest form: the reality we can and/or want to see. In professional practice it is the world we work in/for. This is usually an organisation, a part of an organisation, parts of more organisations together etc. The part we are working for eg the part we are discussing is also called Universe of Discourse (UoD, ISO/IEC term).

• View

  also image or vision. What we see and know of the part of the reality we work in/for. What is seen in a view is determined by background, professional education, interest etc. of the viewer. An IT-professional "sees" other things then a lawyer, for instance.

• Shared

  the views of a certain kind of professionals should be shared to become a shared professional view. So, the IT-professionals of an organisation should share their view so an IT-architecture is formed.

This definition is in line with the definition of the term architecture in the building industry. The architecture of a church is a shared view on this church, where the church is explained in terms of function, structure, beauty and harmony (Vitruvius and Alberti). Read a book on the architecture of such a church, and this is what you will read to "explain" the church.

Information and IT sector

In the IT industry IT-professionals are really engineers putting tools together, hardware and software. They need a design to make the tool that is needed. They create IT-infrastructures. It is very logical the architecture of th infrastructure they are working on must be a model, a method, a development methodology, a documentation method, a modeling language etc. This is what they need to know to be able to build the right tools that will fit their purpose effectively. For that reason these professionals are mainly talking about:

• IT architecture.

  This is the view of IT-professionals on the technical IT-infrastructure, written down in models, languages etc. Here we are talking about the world of the IT-vendors who are creating hardware, networking, systemsoftware etc.: systemhouses. The IT-architecture is a shared view of the technical IT-infrastructure, their reality.

• Enterprise Architecture.

  This is the view of IT-professionals who are concerned with IT-solutions for organisation. The way services/applications/systems/objects/components/... and data (databases, files etc.) fit (business alignment) to an organisation is also best written down in models and languages by people who's job resemble the work of engineers. Again a shared view on the support IT delivers to an organisation, their reality.

  The term Enterprise-IT-Architecture would be must better and clearer for this kind of architecture because the term Enterprise Architecture has been and is the reason for many misunderstandings.

There is a big difference between the way business specialists view their reality and the way IT-professionals view theirs. To bridge this gap it is necessary to have a third architecture:

• Information Architecture.

  The view of information scientists on the information the organisation wants and needs as a corporate resource. This view defines the demand side, while the IT- and Enterprise-Architecture define the supply side.

There are a number of views outside the information and IT views on the organisations. For instance the view on the way the business is organised in business processes, usually called the business architecture. These architectures are not the work of information scientists or IT-professionals. To give a negatively formulated clue: this is where everyone else in the organisation specialises in and working for.

There are a large number of other architecture in the IT world: application, software, hardware, solution, firewall, data, grid, security, system management etc.etc. architectures. They are all part of the IT- and the Enterprise-(IT-)Architecture.