The introduction of lower-level data occurs throughout the engineering process. Sometimes the introduction is due to new data becoming available from a subcontractor, while other times it is because the top-down design process is pushing for more information. Regardless of the reason, the ability to quickly add lower-level data to an existing, self-consistent set of models is critical.The solution is a familiar term, frequently over-used, but not as common in tools as one might hope--Object-Oriented Design. A tool that provides a good object-oriented approach allows the addition of lower-level detail to override a high-level definition.
In eXpress, this is accomplished by linking new designs to existing objects. What eXpress does that is unique is that it retains three modes of hierarchical operation. First, it can switch the relationship to a bottom-up mode, if it is desirable for the lower-level model to be considered as the sole source of information. Second, it can alternatively use a top-down mode so that the top-level can require a particular approach from the lower-level. In this way, it serves as an ongoing requirements flow-down, until such time as the lower-level complies and the system stops changing. Third, a hybrid mode is supported so that some information can flow down, while other information can flow up.
The scalability offered in such an approach is three-fold:
- Early analysis for estimation purposes does not require lower-level data.
- Mixed modes of hierarchical relationships allows convergence towards a solution.
- Mixed modes of hierarchical relationships support different ways of working with subcontractors.
Assessing the engineering tools scalability to these types of problems is an important step in ensuring the ability optimize throughout the engineering process.