Short Tutorial: Enterprise Architecture Concepts

 

Definition: An architecture of a system is a structure that describes three things:

Components of the system (what are the pieces of a system?),
Functions performed by the components (what do they do?), and 
Interfaces/interactions between the components (how do they work with each other?).

This definition is consistent with the IEEE 610.2 definition of an architecture: "The structure of the components, their properties, relationships, and the principles and guidelines governing their design and evolution over time."

Within the context of information systems, several types of architectures have emerged over the years (e.g., business architectures, database architectures, computing architectures, network architectures, and software architectures). In all of these cases, it is useful to remember what are the components of the system, what they do, and how they interface/interact with each other. For example, a business architecture would show the business components (e.g., the business processes), what they do (e.g., satisfy customer needs) and how they interface/interact with each other. 

An enterprise architecture (EA), based on the aforementioned definition of an architecture, shows components of an enterprise, what do they do, and how do they interface/interact with each other. This seems simple enough. However, many different definitions of EA have accumulated since the 1980s. The term ‘enterprise architecture’ was introduced by Zachman  as a way to document the technology attributes of an organization. Modifications and extensions of Zachman’s model have included the Department of Defense Architectural Framework (DoDAF), the Open Group Architectural Framework (TOGAF), the Federal Enterprise Architecture Framework (FEAF), and more. In addition, EA is viewed as a ‘process’, as a ‘result’ of the process, and also as a ‘discipline’ that combines both.  For example:  

Whatever the definition, EA is a consolidation of business and technology that can be of great value to the corporate management as well as CIOs. Here are some possible values of EA:  

 

Figure 1: Conceptual View of an Enterprise Architecture and its Benefits

Figure 1 shows a conceptual view of an EA and its benefits in terms of four broad categories (planning, integration, security, and administration – PISA).  This conceptual view is the foundation of the PISA toolset described later. EAs, however, present many challenges to the organization. Development and maintenance of an EA can be a long and expensive undertaking. It is important to measure ROI of an EA effort. For ROI estimates, tangible measurements of the costs and benefits need to be identified. The costs of establishing an EA can be organized into distinct classes such as financial improvement, constituent services, and reduced redundancy. The benefits have been listed above. Monetizing the different types of costs and benefits facilitates the demonstration of ROI. Besides ROI, considerable effort is needed to make sure that the EA efforts are successful. For example, CIOs and CTOs can be removed from the actual development and the use of the EA document, especially in large organizations. In such cases, a group of architects, each focusing on a different dimension, generally report to a chief enterprise architect, who in turn, reports to the CIO

 

Enterprise Architectures and Integration  -- A Quick Look   

As stated previously, an enterprise architecture describes the enterprise building blocks (the business layer, the application layer, and the technology infrastructure layer), what they do and how do they interface/interact with each other. Let us use Figure 1‑4 for a closer look at enterprise architectures. This figure shows a more detailed view of the enterprise building blocks (business processes needed for the business, enterprise applications that automate the business processes, computing platforms and middleware services that support the applications, and the network services that interconnect the various platforms in an enterprise). These building blocks are represented as horizontal layers – higher level layers are more business oriented and lower level layers are more technology oriented. Different types of architectures at different layers can be envisioned as shown in the vertical bar of Figure 2. For example, business architecture represents the architecture at business process layer, enterprise application architecture represents architecture at application layer, etc. Thus an enterprise architecture represents all the architectures at all layers of an enterprise, i.e., it is the vertical bar in Figure 2. Based on this, we can introduce the following definitions of  enterprise architectures: 

Definition 1. Enterprise Architecture = architecture of architectures.

Definition 2. Enterprise Architecture = Business Architecture +  Application Architecture + Computing Platform Architecture + Network Architecture  


Figure 2: Building Blocks of Enterprise Architecture and Integration

A great deal of information about enterprise architectures is available. Here are some key sources: