Posts Tagged ‘functional analysis’

A Brief Introduction to Systems Engineering

Wednesday, June 27th, 2012


Systems engineering is a specialized set of skills that deal with how large and complex projects are acquired for customers like the US Government. Often applied to the development of weapon systems by the defense industry, this approach was also applied for a time in the software development community.

The benefit of the approach, when practiced properly, is that large acquisitions will be more efficient during their development, they will be more likely to be delivered within their cost and schedule constraints, and they will more likely function as required once deployed.

Introduced in the late 1970’s the approach relies on use of diagrammatic models as a means of understanding the context of the systems, its interfaces and its functional requirements. A seminal textbook on the underlying modeling technique was Structured Analysis and System Specification, written by Tom DeMarco.

The goal for a system, as a prerequisite to full-scale development is to have a complete, correct, and executable specification. To do that, the system’s context, boundary, external entities, interfaces, functions, and data needs are defined throughout the process of modeling the system.

The method uses the power of abstraction to define each level appropriate to its implementation. Abstraction means that only the level of detail required is dealt with at that level, and subordinate details are abstracted and pushed down to the correct level where they are meaning full. For example if the system is military airlift, the highest specification only speaks to the distance, volume, frequency and reliability of transport that is required. The fact fact there may be a new airplane as part of the acquisition, or a ground transportation infrastructure, those are to be considered as lower level components and are separately modeled and specified.

Once potential problems are identified and solved in a process called functional analysis, the resulting models can be converted to a common language set of specification that represent each applicable level of implementation.

Realities of the modern economy, changes in acquisition, including likely reductions in defense funding will affect, and possibility displace, many in the workforce. Even though not in vogue outside of defense, the method still has merit. It simply remains as a challenge to the engineer in transition (from defense to commercial) to discover what concepts and portions of the method are reusable and will complement current commercial development techniques. Understanding these systems engineering concepts will be helpful in preparing for that transition. Although specific techniques may have evolved, the need for correctness in understanding the system being built has not.