Data rolled up to CDW is based on the agreed project paradigm of "last-in wins". That is outlined in the presentation Class Library & Master Data Management here. "Last-in wins" means that the last tool that published with the autocorrelate workflow will have their data rolled up to the CDW. How does a discipline who owns the master data prevent that happening? There are multiple approaches. The first and most obvious is collaboration, advising the offending discipline to correct their data and republish. Or, they may simply publish their data to overwrite the offending data. Or they may request the systems team to write a Rule of Precedence (see below) to prevent such an occurrence.
The LIW paradigm allows for flexibility in the Engineering data flow, for example;- Discipline A may have published some data, Discipline B retrieves the data and indicates to A that it is incorrect. Discipline A may not be able/ready to change and republish, therefore A asks B to modify their data and publish such that CDW is correct. However, in this scenario, these disciplines MUST continue to communicate and update their data. For example, if Discipline A then publishes without updating the specific piece of data referred to by B above, then the correct data provided by B shall be overwritten with incorrect data by A – according to LIW.
Such occurrences as above, may be obviated by writing ‘Rules of Precedence’ (RoP) to ensure that, in the case above, Discipline A’s data never gets overwritten by B. However, in writing such rules, enforcing consistency, has the effect of stifling some of the creativity in engineering. Therefore, such rules normally come into play towards the end of a project – ensuring that key data is not inadvertently overwritten. Given that such rules would need to be executed by the system during publish – which can be seen from the above narrative that while automated can be a lengthy process – it is not recommended to create rules for each and every property. Therefore, any RoP shall be developed as an ongoing activity, identified by each discipline champion for implementation by the systems (integration) team.
