13.5 Middle-Out (Risk-Driven) Performance Modeling
As pointed out earlier, performance modeling is all about risk reduction in general. Now, it isn't all that unusual during development to find certain areas that are critical to the design. They are ones that, should they fail, will bring the project crashing down. In areas such as these, we need great confidence (backed by evidence) that the design will (or should) meet its performance requirements.
If our time-budgeting estimates can be supported with believable data (such as information obtained from earlier projects), then we are on solid ground. If not, however, the project is exposed to tremendous risk of failure. So, in circumstances like this, what can be done to mitigate this risk? One solution is to take a middle-out design approach and apply it to the critical items. In such cases, specific, localized modeling is done to provide confidence in the proposed design. Moreover, it must be done quite early in the design...