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mcrew

README.md

A demo process that hosts a "crew" of machines

This demo process is serves a single "crew" of machines.

See protocol.go for the protocol, and see input.txt for a simple example.

Usage

To build:

go install

Via stdin/out

From this directory:

cat input.txt | (cd ../.. && mcrew -I -O)

Via TCP

From this directory:

(cd ../.. && mcrew -v -t :9000) &
cat input.txt | nc localhost 9000

Via WebSockets

From this directory:

(cd ../.. && mcrew -h :8080 -w -f cmd/mcrew/httpfiles)

Then try http://localhost:8080/static/ws-demo.html.

Via HTTP

ToDo.

Demo: Home Assistant

This code can be used for Home Assistant automation via its WebSockets API.

See

  1. ha-boot.json
  2. specs/homeassistant.yaml
  3. specs/ha-switches.yaml

The file ha-boot.json expects switches switch.lamp and switch.shed_light. Edit accordingly. When you use Home Assistant to turn on switch.lamp, switch.shed_light should turn on.

export SHEEN_HA_PASSWORD=mypassword
mcrew -c ws://HAHOST:8123/api/websocket -t :9000 -s "../../specs" -b ha-boot.json

Features

Using environment variables for WebSocket output

This demo code will use environment variables of the form SHEEN_* that are referenced, with a $ prefix, in messages sent to the WebSocket client connection via "to":"ws". See specs/homeassistant.yaml. A message given to the WebSocket client has strings of the form $SHEEN_* expanded to their corresponding environment variable values (SHEEN_*). This crude mechanism is used in the demo Home Assistant machine to pass a password from the process's environment to Home Assistant.

Timers service

Messages like

{"to":"timers","makeTimer":{"in":"1s","id":"1","message":{"to":"doubler","double":100}}}}}}

will create a timer. The duration ("in":) is expressed in Go time.Duration syntax.

At the appointed time, the process will send the given message to the crew.

The given id can be used to try to cancel the timer (assuming it hasn't fired):

{"to":"timers","deleteTimer":"1"}

HTTP service

Messages like

{"to":"http","request":{"url":"%s", ...},"replyTo":"machine42"}

will result in an asychronous HTTP request. For now, see HTTPRequest in http.go for the supported request structure. The response is submitted as a message to the crew or to the replyTo machine given in the request. For now, see HTTPResponse in http.go for the supported response structure.