无法建立连接，因为目标机器主动拒绝它——我如何检查我的服务器是否正在运行并且客户端是否能够连接

Question

I tried to run a server and a client on local host but an error keeps popping up the sql part is okay i want to send the tuple from client to server then realised server isnt really working how can i run the server and client on the same machine at once and also what is this issue that keeps popping up Server Code:

import socket
import psycopg2 as sq

conn= sq.connect(database="metro", user = "postgres", password = "12345678",host="localhost", port="5432")
cur = conn.cursor()
try:
    s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    print("Socket creation successful")
except:
    print("Socket creation Failed")

port=8050
s.bind(('localhost',port))
print("Socket is binded to", port)
s.listen(10)
print("Socket is listening")

while True:
    c, addr = s.accept()
    print("got connection from", addr)
    var=c.recv(2056).decode()           #Ticket data from CLIENT

    cur.execute("SELECT * from ticket") #Read DATABASE
    rows = cur.fetchall()
    flag=0
    for row in rows:                    #Check DATABASE FOR VERIFICATION
        if row==var:
            flag=1

    if flag==1:
        data= 'Gate opened'.encode()
    else:
        data= 'Ticket Not Found'.encode()

    c.send(data)
    c.shutdown(SHUT_WR)
    s.shutdown(SHUT_WR)

Client Code:

import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #define obj

port = 8050 #port no.
s.connect(('192.168.0.120', port))   #connect to server
data=('1','101','123')
for dat in data:
    print(dat)
    s.send(dat.encode())

vari = s.recv(2056)
print(vari.decode())
s.close()

Traceback (most recent call last): File "C:\\Users\\welcome\\Desktop\\Python\\Metro\\Client.py", line 5, in s.connect(('192.168.0.120', port)) #connect to server ConnectionRefusedError: [WinError 10061] No connection could be made because the target machine actively refused it [Finished in 2.074s]

Answer 1

I have noted some errors in your code.

You may try 'localhost' or '127.0.0.1' in client to connect with server
SHUT_WR should be replaced with socket.SHUT_WR
You should surround network operations with try except block
And there are logically misaligned while loop in server and client.

I have mitigated these errors. You can refer below code.
I just tested this with dummy data, not with database connection.

Server.py

import socket
import psycopg2 as sq
try:
    conn= sq.connect(database="metro", user = "postgres", password = "12345678",host="localhost", port="5432")
    cur = conn.cursor()
    try:
        s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        print("Socket creation successful")
    except:
        print("Socket creation Failed")

    port=8050
    s.bind(('localhost',port))
    print("Socket is binded to", port)
    s.listen(10)
    print("Socket is listening")

    while True:
        c, addr = s.accept()
        print("got connection from", addr)
        var=c.recv(2056).decode()           #Ticket data from CLIENT
        while var:
            cur.execute("SELECT * from ticket") #Read DATABASE
            rows = cur.fetchall()
            flag=0
            for row in rows:                    #Check DATABASE FOR VERIFICATION
                if row==var:
                    flag=1

            if flag==1:
                data= 'Gate opened'.encode()
            else:
                data= 'Ticket Not Found'.encode()
            c.send(data)
            var=c.recv(2056).decode()
        c.close()
except Exception as e:
    print(e)
finally:
    s.close()

client.py

import socket
try:
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #define obj
    port = 8050 #port no.
    s.connect(('127.0.0.1', port))   #connect to server
    data=('1','101','123')
    for dat in data:
        print(dat)
        s.send(dat.encode())
        vari = s.recv(2056)
        print(vari.decode())
except Exception as e:
    print(e)
finally:
    s.close()