What Is Complex About 273 Applications? Untangling Application Architecture Complexity in a Case of European Investment Banking

In this paper, we first derive propositions from the current literature addressing the causes and impacts of application architecture (AA) complexity. We then untangle AA complexity itself by differentiating four types of AA complexity that are mingled in extant literature: interdependency-, diversity-, deviation-, and overlap-related AA complexity. Based on this more differentiated view, we validate the propositions in the setting of a European Bank. Our findings suggest that only interdependency-related AA complexity behaves as currently assumed. Other types show partially opposite effects.