So I was browsing a paywall site that was discussing the involvement of Business Architecture with the Enterprise architecture discipline, and the central discussion theme is where do they meet? It was a detailed discussion with argument all along (well that is EA for you). What I am presenting next is what I feel is the most complying perspective from my point of view.
Business Strategy
The enterprise strategy is better understood through VMOST diagram. This diagram will help in understanding what the enterprise is trying to achieve. This will most likely reflect on the Architecture Principles, Vision and Requirments, and the business architecture layer.
Business Capability
The business capability shows an abstraction of your core business operations and functions. Within the Enterprise Architecture practice, the business capability determines the vision of the architecture practice along with investigating the opportunities and solutions. Specifically, in TOGAF, it will be part of the capability assessment deliverable that will feed into the A and E phases. Its purpose is to increase or optimize the business capability of the enterprise through aligning the IT capabilities with them (IT strategy!)
Business Processes
Well, business processes have been a hot topic since the mid-2000s. So everyone is most familiar is that it shows the how the business processes in your enterprise perform. Aside from the notation importance to the business architects regarding process optimization or even process re-engineering, the enterprise architecture focus on streamlining these processes using IT capabilities. Also, an enterprise architect might use the enterprise continuum as a tool to backtrack the business processes to the verticals they reside on and then try to engineer or optimize them with the help of a business architect to ensure that the enterprise is adhering to the industry while adding its own business or culture requirements.
Organization Structure
The organizational structure, or chart, is the glue that tights the enterprise a whole. It could include locations and might represent the members as roles or actors. It is usually the output from any business architecture practice but will greatly help the enterprise architect in business capability assessment and to know exactly who to talk to too better understand the function for each entity.
But how these business diagrams and tools help the Enterprise Architect? The VMOST is achieved by performing business processes to deliver business capabilities through roles and actors. The combination of all of the factors acting together comprise what is called the operational model. The sole purpose of IT and technology is to support and streamline the operational model in order for the enterprise to achieve its value. And if the IT and technology don’t align well with the operating model then it means that the enterprise is still relying on manual work or shadow IT.
So the purpose of the Enterprise Architecture is to ensure that enterprise optimized to work efficiently (The foundational EA) and to vanguard it against any disruption that might happen (in the Bi-Model).