Discovering the Objectual Meaning of Foreign Key Constraints in Enterprise Applications

The software industry is increasingly confronted with the issues of understanding and maintaining a special type of object-oriented systems, namely enterprise applications. A specific concern for these applications is to understand the persistent data (usually stored in a RDBMS), and its manipulation in the object-oriented source code. While foreign keys are an important means for indicating relations within the persistent data, oftentimes, by looking solely at the database schema, it is impossible to determine the exact nature of these relations. This paper proposes a novel approach for determining a refined understanding of the relations among the persistent data, by correlating the information about foreign keys extracted from the database schema with the way the data are used in the source code. By analyzing two enterprise systems we found that the proposed approach helps specifying a significant number of foreign key constraints in terms of their objectual meaning (e.g., if they denote an inheritance or an aggregation relation). Thus, the approach contributes to enhancing, in an automated manner, the understanding of a system's database schema by tying it to the source code that uses it.