With COTS, there always exists the risk of introducing systematic and non-systematic errors into the existing system.
Systematic errors are repeatable errors and are generally more easy to spot. For example, a computer has an incompatible operating system with the rest of the system and therefore causing the whole system not to function, or a software is not compatible with the operating system and it does not run properly, as it can be seen below:
Figure 1: Incompatible software with the operating system.
Non-systematic errors and/or anomalies may be difficult and almost impossible to find. These errors can be costly or even catastrophic to the system or system performance. Finding these errors are critical in NASA and DoD systems.
A principal risk posed by the use of COTS components in applications lies in the discontinuity it creates in the understanding of the system as a whole. A pictorial of the relationship is shown below:
Figure 2: The relationship between COTS component and target system.
Returning to the standardized JPL COTS procedure, the final 2 of the 7 steps can be accomplished by using a waterfall chart. A figure of one is shown below:
Figure 3: Waterfall chart.
Note: Access the Business Aspects section in the Systems Engineering module on AAQ to learn more about Risk Assessment.