We examine deadlock analysis for service-oriented systems with unbound concurrency and unbound recursion. In particular, abstraction-based approaches are considered, i.e., abstract behavior models are derived from service implementations and composed according to the architecture of service-oriented systems. It turns out that there are some limitations of Petri-net-based approaches, e.g., such as workflow nets if deadlocks are analyzed. We show an example that ends in a deadlock if recursion is considered but on a Petri-net-based abstraction, it may regularly end.