  Extended reality (XR) applications require computationally demanding
functionalities with low end-to-end latency and high throughput. To enable XR
on commodity devices, a number of distributed systems solutions enable
offloading of XR workloads on remote servers. However, they make a priori
decisions regarding the offloaded functionalities based on assumptions about
operating factors, and their benefits are restricted to specific deployment
contexts. To realize the benefits of offloading in various distributed
environments, we present a distributed stream processing system, FleXR, which
is specialized for real-time and interactive workloads and enables flexible
distributions of XR functionalities. In building FleXR, we identified and
resolved several issues of presenting XR functionalities as distributed
pipelines. FleXR provides a framework for flexible distribution of XR pipelines
while streamlining development and deployment phases. We evaluate FleXR with
three XR use cases in four different distribution scenarios. In the results,
the best-case distribution scenario shows up to 50% less end-to-end latency and
3.9x pipeline throughput compared to alternatives.
