VILLASframework
Modular co-simulation framework
VILLASnode

VILLASnode is a modular gateway for simulation data. It offers interfaces to simulation equipment, databases and web services.

Overview

The project consists of a server daemon and several client modules which are documented here.

Features

  • Wide selection of interface types
  • Statistic collection quality of service of the interfaces
  • Web interface for live monitoring and control using WebSocket streams
  • Remote API for control via HTTP or WebSockets
  • Network emulation using the Linux's netem queuing discipline
  • Multicast addressing for Sockets node-type
  • Deterministic and low jitter due to low level C implementation
    • Using the latest C11 standard
    • Easily extensible with new interface types or callbacks (hook functions)
  • Released as open source software under the GPLv3 license
  • Easily deployable via ISO installer, Docker image, RPM packages or from source
  • Only relies on open source software libraries and the Linux kernel
  • Follows the Unix philosophy by providing a set of smaller command line tools
  • Remote configuration by loading configurations files via HTTP, FTP or SSH
  • Result and data profile upload / download via HTTP, FTP or SSH

Daemon

The server simply acts as a gateway to forward simulation data from one client to another. Furthermore, it collects statistics, monitors the quality of service and handles encryption or tunneling through VPNs.

For optimal performance the server is implemented in low-level C and makes use of several Linux-specific realtime features. The primary design goal was to make the behaviour of the system as deterministic as possible. Therefore, it's advisable to run the server component on a PREEMPT_RT patched version of Linux. In our environment, we use a Fedora-based distribution which has been stripped to the bare minimum (no GUI, only a few background processes). Have a look at Tuning for ways to improve the real-time performance of your system.

Clients

There are two types of interfaces to VILLASnode:

  1. The server handles diffrent types of nodes. The most commonly used node-type is the Sockets node-type which allows communication over network links (UDP, raw IP, raw Ethernet frames). But there are also other specialized node types to retreive or send data to equipemnt, which is directly connected to or running on the server itself. An example for such a node is the VILLASfpga node-type which directly fetches and pushes data to a PCIe card. Or the File node-type which logs or replays simulation data from the harddisk.
  2. An other way to connect simulation equipment is by using a client-application which itself sends the data over the network to VILLASnode. In this scenario, VILLASnode uses the Sockets node-type to communicate with the client-application.

Usually, new clients / equipment should be implemented as a new node-type as part of VILLASnode. Using a dedicated client-application which communicates via the 'socket' type is deprecated because it leads to code duplication.