Some definitions of Enterprise Architecture (EA).
1. Enterprise Architecture is a complete expression of the enterprise; a master plan which “acts as a collaboration force” between aspects of business planning such as goals, visions, strategies and governance principles; aspects of business operations such as business terms, organization structures, processes and data; aspects of automation such as information systems and databases; and the enabling technological infrastructure of the business such as computers, operating systems and networks.
2. An enterprise architecture (EA) is a conceptual blueprint that defines the structure and operation of an organization. 数据挖掘研究院
3. The EA is:
What: The structure of an Enterprise and its blueprint describing.
How: How the Enterprise operates and the processes executed by.
Whom: People.
Which: The technology implementing processes.
Where: Showing the location of people and technology.
Why: To streamline, align, blueprint, strategically plan, and confer agility.
When: According to the Enterprise transformation plan to a target state.
4. Enterprise architecture is an agency-wide framework for incorporating business processes, information flows, applications, and infrastructure to support agency goals.
5. Enterprise architecture is the organizing logic for business processes and IT infrastructure.
EA is about describing business and mapping businees to IT systems. It is about guaranteeing that the systems really implement what users need. EA describes which system is responsible for each information asset. 数据挖掘实验室
Having an Enterprise Architecture is a key factor to a successful SOA initiative. Analyzing Enterprise Architecture helps to identify required services for the SOA infrastructure.
Assigning responsibility for the services is part of SOA Governance. EA also helps to do this.
If a company does not have an enterprise architecture, it is very recommended embracing SOA and EA together. 数据挖掘研究院

