Things Bus: Difference between revisions
From Pumping Station One
| (12 intermediate revisions by 2 users not shown) | |||
| Line 10: | Line 10: | ||
There are 3 basic node types in things bus: | There are 3 basic node types in things bus: | ||
* Sensors. | * Sensors. Sensors produce data | ||
* Actuators. | * Actuators. Data Sinks consume data, and probably do something interesting with it. | ||
* Neurons. | * Neurons. Neurons take in sensory data, manipulate it in some way, and send the data to actuators. | ||
=== Sensors === | === Sensors === | ||
A simple of an example of a sensor would be a temperature sense in the space. | A simple of an example of a sensor would be a temperature sense in the space. A temperature sensor would be a Raspberry Pi hooked into a temperature sense, and would send out the current temperature every 5 minutes. | ||
Sensors make data available by using a zmq bind PUB socket. | Sensors make data available by using a zmq bind PUB socket. | ||
| Line 22: | Line 22: | ||
=== Actuators === | === Actuators === | ||
An Actuator is something that, when triggered, does something. | An Actuator is something that, when triggered, does something. It doesn't have to be physical. An actuator could be as simple as an led wired into a Raspberry Pi that can be triggered by a Neuron. | ||
Actuators consume data by using a zmq bind PULL socket | Actuators consume data by using a zmq bind PULL socket | ||
| Line 41: | Line 41: | ||
Examples: | Examples: | ||
* | * A Dust Collection Node would likely be both a sensor (Is it on?) and an actuator (Turn it on) | ||
== A Simple Example == | == A Simple Example == | ||
The following is an example of a Neuron. | The following is an example of a Neuron. It connects to sensory input, the hackerpspace's front and back doors, and sense data to an actuator, zirc, an actuator that writes data to #pumpingstationone on irc.freenode.net | ||
Before running the example, you must have a recent python, recent libzmq installed, and must have pyzmq installed. | Before running the example, you must have a recent python, recent libzmq installed, and must have pyzmq installed. | ||
<syntaxhighlight lang="python"> | |||
#!/usr/bin/env python | |||
import zmq | |||
context = zmq.Context.instance() | |||
# Create a zmq socket that will SUBscribe to door nodes. | |||
door_socket = context.socket(zmq.SUB) | |||
door_socket.connect("tcp://frontdoor.pumpingstationone.org:5556") | |||
door_socket.connect("tcp://backdoor.pumpingstationone.org:5556") | |||
# The doors send a lot of types of messages. We only care about "door.state.unlock" messages | |||
door_socket.setsockopt(zmq.SUBSCRIBE, b"door.state.unlock") | |||
# create a zmq socket that will PUSH data to our IRC actuator node. | |||
zirc_socket = context.socket(zmq.PUSH) | |||
zirc_socket.connect('tcp://sally.ad.pumpingstationone.org:5558') | |||
# Loop forever | |||
while True: | |||
# Read messages from the doors | |||
topic, message = door_socket.recv_multipart() | |||
# Send the message to the irc channel | |||
zirc_socket.send(message) | |||
</syntaxhighlight> | |||
== Hardware == | == Hardware == | ||
We are targetting Beagle Bone Blacks for node hardware. | We are targetting Beagle Bone Blacks for node hardware. While in theory, the hardware can be anything, having a consistent dev platform is useful. | ||
The BBB has 2 blocks of GPIO lines, and the capability of supporting up to 4 Serial devices. A lot of the types of data we want to collect are available over gpio and serial. | The BBB has 2 blocks of GPIO lines, and the capability of supporting up to 4 Serial devices. A lot of the types of data we want to collect are available over gpio and serial. | ||
==Things Bus Broker == | == Things Bus Broker == | ||
For certain types of nodes, a broker that maintains state is useful. | For certain types of nodes, a broker that maintains state is useful. | ||
For details of this system, see https://github.com/eastein/thingsbus | For details of this system, see https://github.com/eastein/thingsbus | ||
== Communication == | == Inter-Node Communication == | ||
{{ambox | |||
|type=content | |||
|text=The code snippits contain errors | |||
}} | |||
The software for a node can be written in any language that supports zmq and json. | The software for a node can be written in any language that supports zmq and json. | ||
Nodes send messages using json data. Sensors use zmq PUB/SUB. Actuators use zmq PUSH/PULL. Neurons use whatever they have to do get the job done, which means they SUB to sensors, and PUSH to actuators. | |||
=== Code Snippits === | |||
Sensors send data like this: | Sensors send data like this: | ||
import zmq | |||
context = zmq.Context.instance() | |||
socket = context.socket(zmq.PUB) | socket = context.socket(zmq.PUB) | ||
socket. | socket.bind('tcp://*:5556') | ||
socket.send_multipart(('dot.delimited.filter', '{"json":"message"}')) | socket.send_multipart(('dot.delimited.filter', '{"json":"message"}')) | ||
Neurons receive data like this: | Neurons receive data like this: | ||
import zmq | |||
context = zmq.Context.instance() | |||
sensor = context.socket(zmq.SUB) | sensor = context.socket(zmq.SUB) | ||
sensor.connect("tcp://sensor.tld:5556") | sensor.connect("tcp://sensor.tld:5556") | ||
sensor.setsockopt(zmq.SUBSCRIBE, b"dot.delimited.filter") | |||
topic, message = sensor.recv_multipart() | topic, message = sensor.recv_multipart() | ||
data = json.loads(message) | data = json.loads(message) | ||
| Line 105: | Line 120: | ||
Neurons send data like this: | Neurons send data like this: | ||
import zmq | |||
context = zmq.Context.instance() | |||
actuator = context.socket(zmq.PUSH) | actuator = context.socket(zmq.PUSH) | ||
actuator.connect('tcp://actuator.tld:5558') | actuator.connect('tcp://actuator.tld:5558') | ||
| Line 111: | Line 128: | ||
Actuators receive data like this: | Actuators receive data like this: | ||
import zmq | |||
context = zmq.Context.instance() | |||
socket = context.socket(zmq.PULL) | socket = context.socket(zmq.PULL) | ||
socket.bind('tcp://*:5558') | socket.bind('tcp://*:5558') | ||
