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Python socket - Messages not always registering on server

In trying to familiarize myself with the socket library, I have a simple server and client setup. Basically I've stumbled through and am able to set up connection and get the server and client to talk to each other. To make it more interactive, I have client.py able to send text through the command line. Everything appears to be working properly (with the exception of the server side tearing down connection properly if client input is blank), if I type a message from the client side, it spits it right back out to me. In this example, I have it set up for the server side to print the text as well. What I noticed was, that the server side doesn't alway 'register' what it being sent from the client. I am trying to figure out why this is the case. For being a test, it doesn't really affect anything, I just can't figure out what is taking place behind the scenes.
EDIT:
Actually, after playing around with it for a bit, it appears every other message is being printed out to the server console. I've still yet to figure out why this is the case
Server side:
#server.py
import socket
ss = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
ss.bind(('127.0.0.1',5000))
ss.listen(5)
while True:
conn, addr = ss.accept()
with conn:
print ('Connected by', addr)
while True:
data = conn.recv(4096)
print (data)
if not data:
print ("nothing received from client")
ss.close()
break
Client side:
#client.py
import socket
server = 'localhost'
port = 5000
s = socket. socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('127.0.0.1', 5000))
s.send(bytes(b'Client has connected'))
while True:
msg = input()
s.send(bytes(input(msg),'utf-8'))
if not msg:
print ("Server should tear down connection...")
# s.close()
break

In sockets you there are no methods __exit__ implemented, so you can't use the with conn:
you need to remove this part of code.

TypeError: str, bytes or bytearray expected, not int [duplicate]

I'm trying to create a simple server to client based chat program and the issue is that when I try to execute c.sendto(data,client) this error appears saying that Client is an int but it's a tuple containing the port number and the address. I'm I supposed to convert the tuple to bytes so I can send the message to the clients?
Server Script
import socket
clients = []
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(("127.0.0.1",7999))
s.listen()
print("Waiting for connection")
c, addr = s.accept()
while True:
data , addr = c.recvfrom(1024)
print(data)
if addr not in clients:
clients.append(addr)
print(clients[0])
if data:
for client in clients:
print(client)
c.sendto(data,client)
s.close()
Client Script
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
addr = ("127.0.0.1",7999)
s.connect(addr)
while True:
string = input(">>")
s.send(string.encode("utf-8"))
data =s.recv(1024)
s.close()
Server Output

The problem is that you're using sendto() with a connection-mode socket. I think you want c.send(data) instead.
Details:
The Python docs for sendto say "The socket should not be connected to a remote socket, since the destination socket is specified by address." Also the man page for sendto says "If sendto() is used on a connection-mode (SOCK_STREAM, SOCK_SEQPACKET) socket, the arguments dest_addr and addrlen are ignored (and the error EISCONN may be returned when they are not NULL and 0)." I somewhat suspect that this is happening and Python is misreporting the error in a confusing way.
The sockets interface and networking in general can be pretty confusing but basically sendto() is reserved for SOCK_DGRAM which is UDP/IP type internet traffic, which you can think of as sending letters or postcards to a recipient. Each one goes out with a recipient address on it and there's no guarantee on order of receipt. On the other hand, connection-mode sockets like SOCK_STREAM use TCP/IP which is a bit more like a phone call in that you make a connection for a certain duration and and each thing you send is delivered in order at each end.
Since your code seems to be designed for communication over a connection I think you just want c.send(data) and not sendto.

You must first convert the string that contains the IP address into a byte or a string of bytes and then start communicating.
According to the code below, your error will be resolved.
Make sure your code is working correctly overall.
string = '192.168.1.102'
new_string = bytearray(string,"ascii")
ip_receiver = new_string
s.sendto(text.encode(), (ip_receiver, 5252))

How to trigger Raspberry Pi 3 to take action from Server

I am currently developing a system where I need to send notification to Raspberry to run a Python file. It is much like a observer pattern design where my server is publisher and Raspberry is the observer. Worth to note that, I actually need to interact with one Raspberry at the time (even I have dozens of them). Specifically, on a specific event, I need to warn a single Raspberry that it has to take an action.
I searched for it literally for all the night but I could not find anything coming handy. Nothing really give me a clue how to implement this.
The most close answer I could find is this technology firm's product called PubNub which can actually work. However, as I need is a one-to-one interaction, this might be unnecessary because it is designed to publish a data to multiple clients.
Long story short, I need to trigger Raspberry to take some action in accordance to the some data coming from the server, whenever it receives the data.
Server is running on Amazon and implemented with Python 2.7.
Please do not hesitate to ask me for further detail, if I am missing any.
Thanks for all the supports,
EDIT
Just a recent update with an improvement to my answer. As far as I understand, sockets are able to manage this process. Such as from client (Raspberry in my case) listening for the server and server sending some data. Taken from this site, I managed to make a sample run on my computer, from my local. I used Port 5000 as their 'meeting point'.
Below is the code:
client.py
#!/usr/bin/env python
import socket
TCP_IP = '127.0.0.1'
TCP_PORT = 5000
BUFFER_SIZE = 1024
MESSAGE = b"Hello, World!"
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((TCP_IP, TCP_PORT))
s.send(MESSAGE)
data = s.recv(BUFFER_SIZE)
s.close()
print("received data:", data)
server.py
#!/usr/bin/env python
import socket
TCP_IP = '127.0.0.1'
TCP_PORT = 5000
BUFFER_SIZE = 20 # Normally 1024, but we want fast response
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((TCP_IP, TCP_PORT))
s.listen(1)
conn, addr = s.accept()
print('Connection address:', addr)
while 1:
data = conn.recv(BUFFER_SIZE)
if not data: break
print("received data:", data)
conn.send(data) # echo
conn.close()
However, I still have some questions.
Firstly, I want to learn whether the same thing work when I deploy the project and how. If that will work - lets say I have an url for the server like 'www.thisisanexampleurl.com' - simply assignign a port for it, will work?
Secondly, assuming first question is done, what is the way of making it continous so that it does not stop after receiving and sending data once. Because currently, when it makes the data transfer, it stops working.
Thanks again for the all support and again please do not hesitate to ask me for the further details i am missing any.

You should be able to do something this simple:
Run something like this on your pi:
import socket
s = socket.socket()
host = ""
port = 12345
s.bind((host, port))
s.listen(5)
while True:
try:
clientsock, addr = s.accept()
except OSError:
continue
message = clientsock.recv(20)
#the code you want to run
print("doing %s" % message)
clientsock.close()
And this on your server every time you want the pi to take action:
import socket
s = socket.socket()
host = "0.0.0.0"
port = 12345
s.connect((host, port))
s.send("foo")
s.close()

Have a look at Pyro4. It lets you avoid having to write network code at all and just write code that calls remote Python objects as if they were running on the same machine. In your case, the server could call a normal Python method on your Raspberry Pi to do something. It has many features but you can start with something extremely simple.
raspberry pi code:
import Pyro4
#Pyro4.expose
class Raspberry:
def something(self, arg):
print("called with:", arg)
return "hi from pi"
Pyro4.Daemon.serveSimple({Raspberry: "raspberry"})
server code to make the pi do something:
import Pyro4
rasp = Pyro4.Proxy("PYRONAME:raspberry")
print(rasp.something(42))

PYTHON - UDP listening without knowing the server

using python2.X (for Linux (++) and Windows (+))
I'm trying to create a python client, to listen to an adress and a port.
The messages are sent by an app on a specific adress and a specific port, but I don't know how it is written. I'm just sure it is functionnal and it uses UDP protocole.
So, I've written this code to receive the messages :
import socket
#---socket creation
connexion = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
#---Bind
try:
connexion.bind(('', 10015))
except socket.error:
print "connexion failed"
connexion.close()
sys.exit()
#---testing
while 1:
data, addr = connexion.recvfrom(1024)
print "messages : ", data
At this point, there is no error running it, but the code stops at this line :
data, addr = connexion.recvfrom(1024)
and nothing happens... I think I'm not connected and can't receive messages but I don't know why.
I tried to change the adresse by : '192.168.X.X', but it's the same.
If anyone could help me, that would be great. I'm not very comfortable why python...
PS : sorry for my english.

I found my problem. I changed the IP adress (in the documentation, it was 192.168. 00 8. 0 15 ; I tried whithout the zeros like a normal adress (192.168.8.15) and I received my messages
I changed the structure of my code too : (don't know if it has impact) I put my "try: [...] except:[...]" on the line
data, addr = connexion.recvfrom(1024)
instead of the line :
connexion.bind(('', 10015))
Thanks for helpping ;)

Your code is all well and fine. You can verify that it works using the following Python snippet:
import socket
connexion = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
connexion.sendto("sending data via udp", ("localhost", 10015))
If a message send with this snippet is not displayed, check your firewall. To investigate whether (or what) your other application is actually producing try using tcpdump or wireshark.

Receiving 'Request String' in Python

I'm building a game-server in Python. The functionality is pretty well-defined. The server will listen on the port 6000 and a remote client will send a request. Then the server will establish a connection to the client's port 7000. From then on, the client will keep sending 'requests' (basically, strings such as "UP#", "DOWN#", "SHOOT#" etc.) to server's port 6000.
This is the problem. I have made a 'server' who listens on the port 6000. This means I cannot bind a client to the same port. Is there a way that I can get the data string of an incoming request in a server? So far, I only have this.
What am I doing wrong here? Any workarounds for this issue? In short, can I read the incoming request string from a client in the server code?
Thanks in advance.
def receive_data(self):
errorOccured = False
connection = None
try:
listener = socket.socket() # Create a socket object.
host = socket.gethostname()
port = 6000 # The port that the server keeps listening to.
listener.bind(('', port))
# Start listening
listener.listen(5)
statement = ("I:P0:7,6;8,1;0,4;3,8;3,2;1,6:5,4;9,3;8,7;2,6;1,4;2,7;6,1;6,3:2,1;8,3;5,8;9,8;7,2;0,3;9,4;4,8;7,1;6,8#\n","S:P0;0,0;0#","G:P0;0,0;0;0;100;0;0:4,3,0;5,4,0;3,8,0;2,7,0;6,1,0;5,8,0;1,4,0;1,6,0#", "C:0,5:51224:824#","G:P0;0,0;0;0;100;0;0:4,3,0;5,4,0;3,8,0;2,7,0;6,1,0;5,8,0;1,4,0;1,6,0#","G:P0;0,1;2;0;100;0;0:4,3,0;5,4,0;3,8,0;2,7,0;6,1,0;5,8,0;1,4,0;1,6,0#")
# This is just game specific test data
while True:
c, sockadd = listener.accept() # Establish connection with client.
print 'incoming connection, established with ', sockadd
i = 0 # Just a counter.
while i<len(statement):
try:
self.write_data(statement[i], sockadd[0])
time.sleep(1) # The game sends updates every second to the clients
i = i + 1
#print listener.recv(1024) -- this line doesn't work. gives an error
except:
print "Error binding client"
c.close() # Close the connection
return
except:
print "Error Occurred"

I'm going to answer it because I got some help and figured it out.
The most basic thing I can do is to use the client connection which is c for this purpose. In here, instead of the commented line data=listener.recv(1024) I should have used data= c.recv(1024). Now it works.
Another way is to use SocketServers with a StreamingRequestHandler. While this is ideal for usage of typical servers, if a lot of objects are involved it could reduce the flexibility.