serial_listen.py

"""
Network Testing Application

This application allows for the sending and retrieval of data across a network
which uses serial ports on multiple machines. It adopts its own protocol and 
allows for text to be sent from one machine to another.

Author: Nick Klose (nick.klose@ualberta.ca)
http://ualberta.ca/~klose
"""
import serial
import threading
import os, sys
import time

class SerialListen(threading.Thread):
    def __init__(self, parent):
        super(SerialListen, self).__init__()
        self._stop = threading.Event()
        
        self.serial = parent.serial # take control of parent's serial connection
        self.ui = parent.ui # enable parent UI updating
        self.input = "" # the string being read from the serial
        self.name = parent.name # save parent name to check if messages are for us
        self.sender = "" # save sender name from serial
        self.recipient = "" # save recipient name from serial
        self.pinger = "" # name of node having sent most recent ping
        self.text = "" # save text message from sender
        self.parent = parent
        self.queue = parent.queue
        self.oldNodes = parent.oldNodes
        self.nodes = parent.nodes
        self.pastNodes = [] # nodes which were detected during the last ping
        
    def run(self):
        while self.serial != None:
            try:
                c = self.serial.read()
                self.input += c
                
                # reset buffer if a new command is sent
                if self.input[-1:] == "{":
                    self.input = "{"
                    
                # end buffer if command close character is sent
                if self.input[-1:] == "}":
                    if self.input[:6] == "{NAME=":
                        pinger = self.input[6:-1]
                        self.pinger = pinger
                        if pinger not in self.nodes:
                            self.nodes.append(pinger)
                        self.update_nodes_in_range()
                    elif self.input[:6] == "{FROM=":
                        self.sender = self.input[6:-1]
                    elif self.input[:4] == "{TO=":
                        self.recipient = self.input[4:-1]
                    elif self.input[:6] == "{TEXT=":
                        self.text = self.input[6:-1]
                        # the recipient is this node
                        if self.recipient == self.name:
                            message = "<From: " + self.sender + "> " + self.text
                            self.ui.listReceivedData.addItem(message)
                        # the recipient is another node, so relay the message
                        else:
                            #self.parent.send(self.sender, self.recipient, self.text)
                            message = "<From: " + self.sender + "> <To: "
                            message += self.recipient + "> " + self.text
                            self.ui.listRelayedData.addItem(message)
                else:
                    try:
                        Image.show(Image.fromstring(self.input))
                    except:
                        pass
                        
                # send any queued messages
                for message in self.queue:
                    self.serial.write(message)
                    del message
            except:
                pass
        
    def update_nodes_in_range(self):
        self.ui.listNodes.clear()
        allNodes = list(set(self.nodes + self.oldNodes))
        for node in allNodes:
            self.ui.listNodes.addItem(node)
        self.oldNodes = self.nodes
        self.nodes = []
        
        # change name if necessary
        if self.name in self.nodes + self.oldNodes:
            self.parent.change_name(self.random_name())
    
    def stop(self):
        self._stop.set()