1.1System planning and enterprise architecture

ES's Part-A-II exam does not test rote definitions such as "what is enterprise architecture"; it tests the ability to judge, given the gap between business strategy/requirements and the constraints of the current system, where the gap lies and which layer (BA/DA/AA/TA) to address first. If, in the early stage of system planning, a review of the business itself (BA) is skipped and only application renewal (AA) proceeds, the old inefficient business process simply gets systematized as-is, and the investment fails to pay off.

1.1.1The four layers of enterprise architecture

• Enterprise architecture (EA) is a framework for systematically designing and managing an organization's business and systems as a whole while keeping them aligned with business strategy. BA (Business Architecture) designs business functions, business processes, and organization. DA (Data Architecture) designs the structure, flow, and location of the data the business handles.
• AA (Application Architecture) designs the configuration and interrelationships of the application functions that support the business. TA (Technical Architecture) designs the technology foundation—hardware, software platform, network, and so on. The four layers form a hierarchy that becomes progressively concrete in the order BA -> DA -> AA -> TA, and renewing only the lower layers (AA/TA) without reviewing the upper layer (BA) does not resolve business inefficiency.

1.1.2As-Is / To-Be gap analysis

• As-Is analysis visualizes the actual state of current business processes, system configuration, and data flow. The To-Be model is the desired shape of the business and systems, derived from business strategy and business goals. Gap analysis identifies the difference between As-Is and To-Be and pinpoints the measures (the scope of business reform and system renewal) needed to close that gap.
• At the planning stage, an architect is expected to be able to explain to management the return on investment (ROI) of the measures that close the gap. Even for measures whose benefit is hard to quantify (such as improved business quality), it is the system architect's role to translate them into measurable indicators—KPIs, projected cost savings—and prioritize accordingly.

Suppose you are the system architect at a mid-size manufacturer, and management hands down the business strategy of "halving the lead time from order receipt to shipment," tasking you with the system planning. The current order management system is aging, and the responsible executive believes "renewing it to a modern package should speed things up." What must be noted here is that the long lead time may not stem from a slow system at all, but from an inefficient business process itself—orders passed repeatedly between departments via paper or email, duplicated approvals, manual re-entry. In this case, renewing only the AA (application architecture) would simply transplant the inefficient process into the new system as-is, and the goal of halving lead time would not be achieved. The appropriate approach is to first visualize the As-Is (the current order-to-shipment process) from a BA (business architecture) perspective, identify duplicated approval routes and manual bottlenecks, design the To-Be (the desired business process), and then, to realize that To-Be, work out in order which data (DA) needs to flow where, what application functions (AA) are needed, and which technology foundation (TA) to choose. Rather than the shortsighted judgment that "a new system automatically speeds up the business," the core of system planning is discerning whether the bottleneck to the business goal lies in the process or the system, and starting from the upper layers of EA.

1.1.3Section summary

• EA is a hierarchy made concrete in the order BA (business) -> DA (data) -> AA (application) -> TA (technology)
• Use As-Is/To-Be gap analysis to identify where the bottleneck lies (business or system) before deciding on measures
• Planning's core is translating return on investment into measurable indicators and starting from the upper layers of EA