Wikipedia provides the following definition:
Enterprise architecture is a comprehensive framework used to manage and align an organisation's business processes, Information Technology (IT) software and hardware, local and wide area networks, people, operations and projects with the organisation's overall strategy.I have highlighted some of the key elements of this definition. EA is about providing a framework that helps to align business processes, IT and people with the overall strategy of the organisation. This is typically captured by considering business process, applications, information and technology as independent views of the enterprise, and then mapping out how they will evolve over time (e.g. via the use of roadmaps, technical strategies and reference architectures). This can be depicted graphically:
Solution architecture is about delivering a project at a particular point in time. In the happy days scenario governance structures are in place to ensure that solution architectures are perfectly aligned with the enterprise architecture, so we can think of each solution architecture as being a ‘snapshot’ of the enterprise architecture at a particular point in time. Again we can model this graphically:
The reality is rarely as clean as the happy days scenario. Governance is more typically a mechanism for identifying divergence from the enterprise architecture, rather than a means of enforcing it, since delivery projects are normally under massive pressure to do the bare minimum to ensure delivery, rather than think of the longer-term implications of the choices made. Solution architectures are thus often misaligned with the EA at best; in some cases they are totally at odds with the EA. This is shown below:
More on governance in the future...