EA consists of a series of architecture activities that will be conducted at the whole organisation wide. It's always advisable to do EA at organization level instead of business unit level since by putting same standard throughout the whole company might save you a bit of efforts of re-accessing company's mission and vision all over again whenever there is such a need to do EA outside one business unit.
EA consists BA(Business Arch), IA(Information Arch), AA(Application Arch) and TA(Technology Arch). It's also recommended to do EA following this sequence however under certain situation in some org they actually did TA first. (to be explained later.)
BA is the base of EA. It shall be conducted by business users with little involvement from IT. It's one of common errors seen that IT drives BA. IT doesnt own the business and should not be reliable to make business decision. The right question IT shall ask is "What shall we do" instead of "What can we do". BPR(Business Process Reengineering) is another topic that confuses people with BA. BA is not BPR, although in some BA practise, BA might result in a BPR. Yes, it's inevitable during any BA practise, business process shall be analyzed and even redesigned if necessary. Still, BA and BPR is just two different things, from the scope, stakeholder, actions taken to the ultimate goals.
After done BA, the company shall have a clearer picture of current situations and ideal outcome for this EA. What comes next is how IT can help to achieve defined targets. AA and IA servers the purpose. Basically, IA and AA is trying to convert business problems into IT problems. What applications to be developed or retired? What modifications or new features needed? Buy in, outsourcing, or in-house development? Integration and Interoperability are two major concerns that often will be addressed.
TA are a set of rules for IT department and it is like to work out a Quality Manual.
In short, EA is not an easy practise and it always spends over months even years to complete a full circle. And the most challenging part is always to get the full support from top management. Without that, any attemp to do a great EA will hardly become successful.
