a streamtools pattern describing a poisson process

PoissonProcess.json

{"label":"root","blocks":[{"label":"","type":"exponential","id":1,"inputs":[{"name":"rate","value":{"data":1},"type":"number"}],"outputs":[{"name":"draw","type":"number"}],"source":null,"position":{"x":263,"y":345}},{"label":"","type":"delay","id":2,"inputs":[{"name":"in","value":{"data":1},"type":"any"},{"name":"duration","value":null,"type":"string"}],"outputs":[{"name":"out","type":"any"}],"source":null,"position":{"x":578,"y":330}},{"label":"","type":"toString","id":4,"inputs":[{"name":"in","value":null,"type":"any"}],"outputs":[{"name":"out","type":"string"}],"source":null,"position":{"x":387,"y":345}},{"label":"","type":"concat","id":5,"inputs":[{"name":"a","value":null,"type":"string"},{"name":"b","value":{"data":"s"},"type":"string"}],"outputs":[{"name":"a+b","type":"string"}],"source":null,"position":{"x":486,"y":345}},{"label":"","type":"log","id":9,"inputs":[{"name":"log","value":null,"type":"any"}],"outputs":[],"source":null,"position":{"x":713,"y":330}}],"connections":[{"from":{"id":2,"route":0},"to":{"id":9,"route":0},"id":10},{"from":{"id":4,"route":0},"to":{"id":5,"route":0},"id":6},{"from":{"id":5,"route":0},"to":{"id":2,"route":1},"id":7},{"from":{"id":1,"route":0},"to":{"id":4,"route":0},"id":8}],"groups":[{"id":0,"label":"root","children":[1,2,4,5,9],"position":{"x":0,"y":0}}],"sources":[],"links":[]}

This works by converting an exponentially distributed random number into a duration string and using that duration to control the flow of the output. The output is whatever the value of the delay block's in route is, with an exponentially distributed inter-arrival time.