Envoy XIPC SubSystems
QueSys, the in-memory high-performance Queuing Subsystem: Supports network-transparent memory-based message queuing with a major emphasis on very high-performance application message queuing within network and stand-alone settings.
KeySys, the ultra‑low‑latency, durable in‑memory Key‑Value Store Subsystem: delivering sub‑millisecond reads and writes with seamless network transparency and built‑in persistence for mission‑critical, real‑time applications.
MemSys, the Shared Memory Subsystem: Supports network-transparent memory sharing between disparate application processes. Besides providing virtual access to shared memory segments, MemSys also supports the ability to dynamically lock, unlock, and asynchronously monitor changes to regions of shared memory, with the granularity of a single byte.
SemSys, the Semaphore Subsystem: Supports network-transparent semaphore synchronization between processes spread over a network. The primary focus of SemSys is support of network-transparent asynchronous event synchronization. SemSys additionally supports resource-contention management facilities.
You can find more information about Envoy XIPC in the online documentation.