On the use of replacement messages in API deprecation: an empirical study

Abstract

As any other software system, frameworks and libraries evolve over time, and so their APIs. Consequently, client systems should be updated to benefit from improved APIs. To facilitate this task and preserve backward compatibility, API elements should in theory be deprecated with clear replacement messages. However, there are evidences that APIs are usually deprecated without such messages. In this dissertation, we explore a set of questions regarding the adoption of deprecation messages. Our goals are twofold. First, to reveal the usage of API deprecation messages in a large sample of client systems; second, to investigate whether tools can be designed to recommend such messages. To achieve these goals we perform an empirical study using 622 Java systems and 229 C# systems. We show (i) the frequency of deprecated elements with replacement messages, (ii) how this frequency over along time, and (iii) the key characteristics of systems with API elements deprecated in a correct way.