Interaction Faults Caused by Third-Party External Systems - A Case Study and Challenges

Interaction faults caused by a flawed external system designed by a third party are a major issue faced by interconnected systems. In this paper, we define a scenario where this type of problem occurs, and describe some fault cases observed in real systems. We also discuss the most important challenges faced in this scenario, focusing on error detection. The problem is divided in several sub-problems, some of which can be addressed by traditional or simple techniques, and some of which are complex problems by themselves. The purpose of this paper is not to present ad hoc solutions to specific sub-problems, but to introduce a new scenario and give general approaches to address each sub-problem. That includes a detailed insight on important concepts, such as implicit redundancies. With this, we lay down the foundations for a wide range