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Utilities and Helpers

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Stephen von Takach edited this page Jun 16, 2017 · 9 revisions

Engine comes packaged with some handy helper functions that make interfacing with the wide variety of IoT protocols out there easier.

Functions and Constants

These can be included into your driver class

include ::Orchestrator::Constants
Helper Type Description
On, Down, Open bool true Constants that can make code more readable
Off, Up, Close, Short bool false Constants that can make code more readable
in_range(input_number, max, min = 0) returns a number in the range if input exceeds the limits, the limit is returned
is_affirmative? value returns true if value is affirmative values such as: true 'yes' :On
is_negatory? value returns true if value is negative values such as: false 'no' :Inactive

The Constants include module also contains Configuration Helpers

include ::Orchestrator::Transcoder
Helper Type Description
hex_to_byte(data) returns binary string accepts any string containing hex characters and supports common formatting such as "0xDEADBEEF", "De:ad:Be:ef" etc
byte_to_hex(data) returns an ascii string accepts binary strings or arrays of bytes
str_to_array(data) returns an array of bytes accepts strings
array_to_str(data) returns a binary string accepts array of bytes

Protocols

Telnet

Implements the telnet standard so that it is easy to communicate with devices that implement control codes or require negotiation.

require 'protocols/telnet'

class TelnetClient
    def on_load
        new_telnet_client

        # Telnet client returns only relevant data for buffering
        config before_buffering: proc { |data|
            @telnet.buffer data
        }
    end

    def disconnected
        # Ensures the buffer is cleared
        new_telnet_client
    end


    def some_request
        # Telnet deals with end of line characters
        # (may have been negotiated on initial connection)
        send @telnet.prepare('some request')
    end

    protected

    def new_telnet_client
        # Telnet client needs access to IO stream
        @telnet = Protocols::Telnet.new do |data|
            send data
        end
    end
end

KNX

Constructs KNX standard datagrams that make it easy to communicate with devices on KNX networks.

For more information see: https://github.com/acaprojects/ruby-knx

OAuth

For secure delegated access to services that implement it see wikipedia for details

require 'protocols/oauth'

class HttpClient
    # =====================================
    # Hook into HTTP request via middleware
    # All requests will be sent with OAuth
    # =====================================
    def on_update
        connected
    end

    # This is called directly after on_load.
    # Middleware is not available until connected
    def connected
        @oauth = Protocols::OAuth.new({
            key:    setting(:consumer_key),
            secret: setting(:consumer_secret),
            site:   remote_address
        })
        update_middleware
    end

    protected

    def update_middleware
        # middleware is service helper function
        mid = middleware
        mid.clear
        mid << @oauth
    end
end

SNMP

Provides an evented IO proxy for ruby-netsnmp

require 'protocols/snmp'

class SnmpClient
    include ::Orchestrator::Constants
    udp_port 161

    def on_unload
        @client.close
    end

    # This is called directly after on_load.
    # Middleware is not available until connected
    def connected
        proxy = Protocols::Snmp.new(self)
        @client = NETSNMP::Client.new({
            proxy: proxy, version: "2c",
            community: "public"
        })
    end

    def query_something
        self[:status] = @client.get(oid: '1.3.6.1.2.1.1.1.0')
    end

    def set_something(val)
        @client.set('1.3.6.1.2.1.1.3.0', value: val)
        self[:something] = val
    end

    protected

    def received(data, resolve, command)
        # return the data which resolves the request promise.
        # the proxy uses fibers to provide this to the NETSNMP client
        data
    end
end

SOAP Services

Probably the easiest way to use these services at the moment via a Logic module. There are a number of supported ruby gems:

Savon usage:

# Ensure we are not blocking the IO reactor loop
require 'httpi/adapter/libuv'
require 'savon'
HTTPI.adapter = :libuv

# Make requests as per the savon documentation
client = Savon.client(wsdl: 'https://aca.im/service.wsdl')
logger.debug { "Available operations: #{client.operations}" }

Handsoap usage:

# Ensure we are not blocking the IO reactor loop
require 'handsoap/http/drivers/libuv_driver'
Handsoap.http_driver = :libuv

# Make requests as per the handsoap documentation

Wake on Lan

Wake on lan is available to drivers of all types

# Supports any string with the correct number of hex digits
#  as well as common formats (these are some examples)
mac_address_string = '0x62f81d4b6f00'
mac_address_string = '62:f8:1d:4b:6f:00'
mac_address_string = '62-f8-1d-4b-6f-00'

# Defaults to broadcast address `'255.255.255.255'`
wake_device(mac_address_string)

# You can define a VLan gateway for a directed broadcast (most common in enterprise)
wake_device(mac_address_string, '192.168.3.1')

CRC Checks

github project and supported crc checks

  • gem install crc

Usage

require 'crc'
crc = CRC::CRC16_CCITT.new
crc.update "\x12\x34\x56\x78\x90"
crc.digest # => "ca"
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