An asynchronous or ``event-driven program is one that contains procedure calls which are not directly executed from the callsite, but stored and executed later by an external scheduler.
Queueing networks are ubiquitous, serving as models of computer networks, service stations, dams, etc. Their performance depends on their structure, parameters and on the service rules.
We construct a universal code for stationary and memoryless classical-quantum channel as a quantum version of the universal coding by Csisz\\'{a}r and K\\ {o}rner.
We consider a single-server discrete-time system with $K$ users where the server picks operating points from a compact, convex and coordinate convex set in $\\Re_+^K$.
