The Advanced RTI System (ARTÌS) is a middleware for Parallel and Distributed Simulation (PADS) supporting massively populated models [FIRB2005]. The design of the middleware is inspired by the IEEE 1516 standard but new features have been introduced to improve scalability and simulation speed.

A PADS is composed by many interacting Logical Processes (LPs), therefore the execution speed is highly affected by the communication performance between the LPs. The approach followed by ARTÌS is adaptive and exploits the LPs physical allocation. Specifically, a couple of LPs running on the same PEU will communicate using the low latency shared memory. In the case of LPs connected by LAN, WAN or Internet, they will communicate using the R-UDP/IP or TCP/IP protocols. The protocol choice is adaptive and based on the network performances.

Other important features of the middleware are the multi-threading support, the implementation of data structures specifically tailored for the event-list management, the capability to detect and adapt to Hyper-Treading and Multi-Core CPUs, and the support for the Simulation Cloning and Concurrent Replication of Independent Runs [HPC2005].