EventMachine server and serial-port using SQL - ruby

Question

I'm new to Ruby.
I'm trying to make an app that reads from a serial-port and puts values into a sqlite3 database. When a client connects via TCP socket he should recieve values from the db. Values written by the client should be sent via serial-port.
I have two questions regarding my app.
This would open one connection to the db on the main thread(?) and one for each client..
Is there a better way to use sqlite3?
I think i figured this out. sqlite3 is not thread safe by defaul,t so this seems like the way to do it..
How do i write to the serialport in the recieve_data method? Is it okay to make serial a global variable?
#!/usr/bin/env ruby
#
# server_1
require 'rubygems'
require 'eventmachine'
require 'sqlite3'
require 'em-serialport'
require 'json'
module SocketClient
def self.list
#list ||= []
end
def post_init
SocketClient.list << self
#db = SQLite3::Database.new( "data.db" )
values = []
#db.execute("SELECT * FROM values") do |row|
values << {row[0] => row[1]} #id => value
end
self.send_data "#{values.to_json}\n"
p "Client connected"
end
def unbind
SocketClient.list.delete self
#db.close
end
def receive_data data
p data
#How do i send via serialport from here??? serial.send_data data
end
end
db = SQLite3::Database.new( "data.db" )
EM.run{
EM.start_server '0.0.0.0', 8081, SocketClient
serial = EM.open_serial '/dev/tty.usbserial-xxxxxxxx', 9600, 8, 1, 0
serial.on_data do |data|
#Parse data into an array called values
db.execute("UPDATE values SET value = ? WHERE id = ?", values["value"], values["id"])
SocketClient.list.each{ |c| c.send_data "#{values.to_json}\n" }
end
}
db.close

Answer 1

Setup the constructor for your Socket client so that it will receive the shared serial connection.
module SocketClient
def initialize serial
#serial = serial
end
def receive_data data
p data
#serial.send_data data
end
Then pass it when you call EM.start_server
EM.run{
serial = EM.open_serial '/dev/tty.usbserial-xxxxxxxx', 9600, 8, 1, 0
EM.start_server '0.0.0.0', 8081, SocketClient, serial