Making Software

So How Much Architecting Is Enough?

We can now use the calculations in the previous sections to provide a rough answer to this central question in project planning.

The project that motivated this analysis was a very large software project (over 10,000 KSLOC) that wanted to get the suppliers on the job quickly, at the risk of spending an inadequate amount of time in system architecture and risk resolution before putting supplier plans and specifications into their Requests for Proposals (RFPs). The project needed to determine its “sweet spot” between the risk of having the suppliers deliver incompatible components, thus incurring schedule overruns due to rework, and the risk of spending too much time on system architecting and risk resolution, which might not leave enough time for the suppliers to develop their system components. This section shows how the COCOMO II RESL factor results were used to determine an adequate architecting “sweet spot” for this project and other sizes of projects.

The full set of effects for each of the RESL rating levels and corresponding architecting investment percentages are shown in Table 10-4 for projects of size 10, 100, and 10,000 KSLOC. Also shown are the corresponding percentages of total delays in delivery, obtained by adding the architecting investment time to the rework time, assuming constant team size during rework in order to translate added effort into added schedule. The bottom two rows of Table 10-4 show that the added investments in architecture ...