handle AVL messages with iodine - ruby

Question

Right now I'm developing a some sort of parser for the messages of the Skypatrol TT8750+ and my threaded TCP server is working. The problem is that it isn't a good approach if there are to many devices connected at the same time. I'm using iodine but I can't make work some code that was given to me. My goal is to receive first a 33bytes message to identify the device and then start to receive 86bytes messages with information of the vehicle.
require 'iodine'
# define the protocol for our service
class TT8750plus
#timeout = 10
def on_open
puts "New Connection Accepted."
# this file is just for testing purposes.
t = Time.now.strftime("%d-%m-%Y %H%M")
file_name = t + '.txt'
#out_file = File.new(file_name, "w+")
# a rolling buffer for fragmented messages
#expecting = 33
#msg = ""
end
def on_message buffer
length = buffer.length
pos = 0
while length >= #expecting
#msg << (buffer[pos, #expecting])
#out_file.puts(#msg.unpack('H*')[0])
length -= #expecting
po += #expecting
#expecting = 86
#msg.clear
end
if(length > 0)
#msg << (buffer[pos, length])
#expecting = 86 - length
end
puts #msg
end
def on_close
#out_file.close
end
end
# create the service instance
Iodine.listen 12050, TT8750plus
# start the service
Iodine.start
And this error appears on every message
New Connection Accepted.
Iodine caught an unprotected exception - NoMethodError: undefined method `+' for nil:NilClass
iodineServer.rb:26:in `on_message'
iodineServer.rb:1:in `on_data'Iodine caught an unprotected exception - NoMethodError: undefined method `+' for nil:NilClass
Also this implementation doesn't get the messages I need
These are the first two lines that I got from this implementation:
0021000a0800000000000120202020202038363332383630323034333433373020
0021000a08000000000001202020202020383633323836303230343334333730200056000a08100020202020202038363332383630323034333433373020014b0000
And these are the first two lines from the threaded implementation
0021000a0800000000000120202020202038363332383630323034333433373020
0056000a08100020202020202038363332383630323034333433373020000b00000013090044709bfb8109e400000000001100000000000067eb11090c1512012e970020000000000005000000000005000000000007
0056000a08100020202020202038363332383630323034333433373020010b00000013090044709bfb8109e400000000001200000000000067eb11090c1512042e970020000000000005000000000005000000000008

Answer 1

This looks like a variation of the untested code I posted earlier.
It seems the issue is with a spelling mistake in the code (probably mine?).
The po += ... should have been pos += ...
require 'iodine'
# define the protocol for our service
class TT8750plus
#timeout = 10
def on_open
puts "New Connection Accepted."
# this file is just for testing purposes.
t = Time.now.strftime("%d-%m-%Y %H%M")
file_name = t + '.txt'
#out_file = File.new(file_name, "w+")
# a rolling buffer for fragmented messages
#expecting = 33
#msg = ""
end
def on_message buffer
length = buffer.length
pos = 0
while length >= #expecting
#msg << (buffer[pos, #expecting])
#out_file.puts(#msg.unpack('H*')[0])
length -= #expecting
pos += #expecting # the spelling mistake was here
#expecting = 86
puts "wrote:", #msg
#msg.clear
end
if(length > 0)
#msg << (buffer[pos, length])
#expecting = 86 - length
end
puts("Waiting for more data:", #msg) unless #msg.empty?
end
def on_close
#out_file.close
end
end
# create the service instance
Iodine.listen 12050, TT8750plus
# start the service
Iodine.start
Again, lacking an emulation for the Skypatrol TT8750+, I can't test the code. But it should be possible to follow error messages to slowly track down these types of issues.
P.S.
To protect from exceptions, consider using Ruby's:
begin
# code
rescue => e
# oops something happened. i.e.
puts e.message, e.backtrace
end
i.e., the on_message method might look like this:
def on_message buffer
begin
length = buffer.length
pos = 0
while length >= #expecting
#msg << (buffer[pos, #expecting])
#out_file.puts(#msg.unpack('H*')[0])
length -= #expecting
pos += #expecting # the spelling mistake was here
#expecting = 86
#msg.clear
end
if(length > 0)
#msg << (buffer[pos, length])
#expecting = 86 - length
end
puts #msg unless #msg.empty? # print leftovers for testing...?
rescue => e
# oops something happened. React
puts e.message, e.backtrace
end
end
Also, FYI, iodine allows you to control the number of processes (workers) and threads you'r using. See the documentation for details.