Enforcing Exception Handling Policies with a Domain-Specific Language

Current software projects deal with exceptions in implementation and maintenance phases without a clear definition of exception handling policies. We call an exception handling policy the set of design decisions that govern the use of exceptions in a software project. Without an explicit exception handling policy, developers can remain unaware of the originally intended use of exceptions. In this paper, we present Exception Handling Policies Language (EPL), a domain-specific language to specify and verify exception handling policies. The evaluation of EPL was based on a user-centric observational study and case studies. The user-centric study was performed to observe how potential users of the language actually use it. With this study, we could better understand the trade-offs related to different language design decisions based on concrete and well-documented observations and experiences reported by participants. We identified some language characteristics that hindered its use and that motivated new language constructs. In addition, we performed case studies with one open-source project and two industry-strength systems to investigate how specifying and verifying exception handling policies may assist in detecting exception handling problems. The results show that violations of exception handling policies help to indicate potential faults in the exception handling code.