Lab 12: WebSockets

In this lab we will show you the VILLASnode WebSockets mockup. The mockup is a simple webpage which receives / sends simulation from / to VILLASnode by using low latency WebSockets.

This technique is usefull for live monitoring and user interaction with simulations.

The configuration file

nodes = {
   udp_node1 = {
           type = "socket",
           layer = "udp",

           in = {
                   address = "*:12000"

                   signals = {
                           count = 8,
                           type = "float"
                   }
           },
           out = {
                   address = "127.0.0.1:12001"
           }
   },
   web_node1 = {
           type = "websocket",

           vectorize = 2,
           series = (
                   { label = "Random walk", unit = "V"   },
                   { label = "Sine",        unit = "A"   },
                   { label = "Rect",        unit = "Var" },
                   { label = "Ramp",        unit = "°C"  }
           )
   }
}

paths = (
   {
           in  = [ "udp_node1" ],
           out = [ "web_node1" ],

           hooks = (
                   # We dont want to overload the WebBrowsers
                   { type = "decimate", ratio = 2 }
           )
   },
   {
           in  = [ "web_node1" ],
           out = [ "udp_node1" ]

           # Web -> UDP does not require decimation
   }
)

Start node and signal generator

$ villas signal -v 4 -r 120 mixed | villas pipe -x lab3.conf udp_node1 &
$ villas node lab12.conf

Web Mockup

Go to [lab 13] =>(node-lab-13)