A Proposed Sizing Model for Managing 3rd Party Code Technical Debt

Commercial software development projects frequently build code on third-party components. However, depending on third-party code requires that projects keep current with the latest version of each component. When projects do not stay current, they begin to incur a form of technical debt where API calls that have been deprecated remain in the code base. At some point, projects must upgrade the third-party component to remain on a supported version of the component. Then the projects incur the cost of paying down the debt that was built up over time. The model described herein intends to estimate the cost of paying down the debt for aging third-party components. The model is a sigmoid curve that exponentially increases the size of changes required to migrate to the new version as a function of time asymptotically approaching the size for replacing the entire component. The longer the number of elapsed years, the greater the increase in the principal measured as the number of affected lines of code in the user of the third-party software component. This exponential increase in principal is reasonable when we consider longer time horizons are more likely to require replacement of the third-party component entirely due to newer technologies becoming available. Effects of the model were estimated using Monte Carlo simulation due to limited examples of third-party technical debt available for modeling.