Increasing the robustness of a service in a complex information flow

Sammanfattning: In complex information flows where a lot of varied data is transmitted through many companies and divisions, incidents will occur. When Visma Spcs had an incident where invoices sent from Visma to Visma's customers were duplicated and the service meant to receive the transactions did not handle the duplicates properly. They decided that the receiver service was to be upgraded to prevent this incident from happening again, as well as fixing some other issues the service had had. Incidents like this one must be investigated and a solution must be implemented to decrease the likelihood that similar incidents will happen again. In this report, the reader will see examples on how this can be handled and the benefits of tackling technical debt, along with how much more complicated the solutions might get if the service is not allowed to be taken offline.